INTRODUCTION, PURPOSE AND SCOPE OF THE STUDY
As part of the Counterminous United States Mineral Assessment Program (CUSMAP), the United States Geological Survey found
anomalous copper in stream sediments from washes draining Black
Mountain and the Batamote Mountains, two miles south and ten miles
northeast of Ajo, Arizona, respectively.
The anomalous area defined
by the values to the northeast of Ajo encompasses the northwestern
two -thirds of the Batamote range.
However, the source of the values
was not determined by the U.S.G.S.
The purpose of the present study is to define, characterize
and explain this anomaly.
Five mechanisms are considered to be
possible explanations of the anomaly:
1.
Airborne contamination from a smelter located in Ajo;
2.
Abnormally high background copper concentrations in the
volcanics composing the Batamote Mountains;
3.
Primary hydrothermal mineralization within the study area;
4.
Dispersion through the volcanic pile along normal
faults; and
S.
Contamination of the volcanics immediately before or
during their eruption.
Each of these working hypotheses should have a unique dispersion
pattern and a characteristic partitioning of copper among mineral
phases.
1
2
The smelter is located just south of Ajo.
Smelters are
known to produce anomalies in soil samples, and the wind in the area
was observed to blow southwest to northeast at times; consequently,
airborne dispersion from the smelter could produce, the observed
anomalies.
Dispersion from this source would tend to have a plumose
form and decrease in intensity downwind.
Any copper would be held
in glass as part of the smelter dust.
The second possible mechanism, abnormally high background
values, would be characterized by a highly uniform distribution of
high values within the stream sediments.
Additionally, the source
rock unit would have to have high copper concentrations; the copper
would probably be held as a trace component within silicate minerals.
Primary hydrothermal mineralization would be characterized by
a dispersion pattern localized around the mineralization.
anomalies would tend not to be very widespread.
As such,
Given the aridity and
nature of weathering in the Batamote Mountains, primary copper minerals
could be preserved in sediments in addition to secondary minerals and
oxides.
Dispersion of copper along normal faults would yield broad
dispersion patterns at the surface, related spatially to the faulting.
Copper would probably be held in oxide coatings, organics or as
chrysocolla.
The final mechanism considered, contamination of the volcanics
before or during their eruption, would produce uniformly high values
in streams draining the volcanics or a zonation about the volcanic
center.
If the contaminants were not assimilated, the bulk of the
3
volcanics would not contain unusual values of copper --only xeno-
lithic fragments would contain anomalous copper.
However, if the
hypothesized contaminants were totally assimilated, the dispersion
would be similiar to that observed for an andesite with high background copper; therefore, this mechanism could be indistinguishable
from an andesite with high background.
Given the expected responses for the five different mechanisms, the purpose of this study is to define the surficial dispersion
of copper, both mineralogically and areally, within the Batamote
Mountains.
This information, in combination with lithogeochemical
and geological data can then be used to infer the genesis of the
copper anomaly discovered by Barton and others (1982).
The study was conducted in three stages: 1. Resampling of
the sites found to be anomalous by Barton and others (1982); 2. High
density collection of stream sediment and heavy mineral concentrate
samples; and 3. Reconnaissance geologic mapping, rock chip sampling
and resampling the anomalies found in the second step.
Field and
analytical work was performed between December, 1982 and February,
1984.
LOCATION, PHYSIOGRAPHY AND CLIMATE
The study was conducted in the Batamote Mountains which are
within the Basin and Range Province of southwestern Arizona- -five to
ten airmiles (8 to 16 km) northeast of Ajo in Pima County.
Ajo is
the site of Phelps Dodge's New Cornelia porphyry copper deposit and
the previously mentioned smelter.
Figure 1 shows the location of
the thesis area in relation to Ajo, Phoenix, and Tucson.
The study
area lies almost entirely within the Ajo and Sikort Chuapo 15minute U.S.G.S. quadrangles.
The mountains trend west -northwesterly and have a length
of twelve miles (19 km) and a width of up to five miles (8 km).
Maximum elevation is 3202 feet (972 m) with relief of up to 1700
feet (520 m).
Physiographically, the mountains occur as relatively
low plateaus surrounding a high central peak that has the appearance of a dissected stratovolcano (see Figure 2).
However, the
preserved surface of the peak is not depositional (Gilluly, 1946).
The mountains have relatively youthful drainages which are characterized by narrow canyons with moderate to steep gradients (Gilluly,
1937)
.
The area around Ajo receives an average of nine inches of
precipitation annually, with the rainiest months being July and
August (NOAA, 1981).
Temperatures range from 30 °F to 120 °F (0 °C
to 50 °C) with temperatures in excess of 100 °F (38 °C) common from
4
S
May to September.
washes.
Consequently, drainages in the area consist of dry
Field observations indicate that the wind often blows from
the southwest to the northeast, creating a potential for airborne
smelter contamination in the study area.
6
GILA BEND
AJO
10 MILES
LUKEVILLE
r
TUCSON
N
100 MILES
Figure 1 -- Location of study area
/
Figure 2 -- Photograph, looking east, of the high point, Batamote
Mountains
PREVIOUS WORK
Previous work on the geology, surficial geochemistry and
geophysics of the Batamote Mountains is contained within reports
encompassing larger or nearby areas.
with Joralemon's report in 1914.
pared in 1984 by Harris.
Early work in the area began
The most recent report was pre-
Existing literature pertaining to the
geology, geochemistry and geophysics of the area is reviewed in
this section.
Geology
Joralemon (1914) discussed the history and economic geology
of the Ajo district.
DeKalb (1918) and Ingham and Barr (1932) dis-
cussed the same topics, but they also concentrated on the mining
methods employed at the New Cornelia Mine.
These three papers refer
only briefly to the geology outside the immediate Ajo district.
Bryan (1928) described the physiography and geology of the
Batamote Mountains in general terms.
Additionally, he described
the log of a well located one mile west of the mountains.
Through
1936 this is the only paper that described the geology of the area
of interest.
In 1935, Gilluly published the first of four papers that
are probably the best work on the geology of the Ajo area.
In
this paper Gilluly described the history and geology of the Ajo
mining district.
However, in papers published in 1937. 1942 and
8
9
1946, Gilluly discussed the geology and physiography of the Ajo 15minute quadrangle in addition to the district geology.
These papers
contain excellent descriptions of the geology, lithology and physiography of the western half of the Batamote Mountains.
Following the last Gilluly paper, there was a long hiatus
on publications relating to the Ajo area.
Dixon (1966) and Wadsworth
(1968) described the geology of the New Cornelia Mine and Cornelia
pluton, respectively.
Jones (1974) discussed the geology of the
Ajo Range, south of the study area.
The most recent publication covering the Batamote Mountain
area is a compilation of the geology of the Ajo 1 °by 2°quadrangle
by Kahle and others (1978).
As this is part of CUSMAP, more litera-
ture should be forthcoming from this group.
The geology of the Hat Mountain and Sikort Chuapo 15- minute
quadrangles has been mapped and reports are in preparation as part
of a cooperative study between the U.S. Geological Survey and the
Bureau of Indian Affairs on the geology and mineral resources of
the Papago Indian Reservation (Haxel and others, 1980).
Surf icial Geochemistry
Also as part of CUSMAP, the U.S. Geological Survey conducted
a reconnaissance exploration geochemistry study over the Ajo 1° by 2°
quadrangle (Barton and others, 1982).
Anomalies discovered as part
of this project served as the impetus for the present study.
Most
recently, Theobald and Barton (1983) discussed the statistical
10
relationships within the U.S.G.S. data.
More literature should come
out of this group in the future.
Geophysics
Finally, Klein (1983) published a residual aeromagnetic map
of the Ajo and Lukeville 1° by 2° quadrangles.
Raines and Theobald
(1981) are conducting remote sensing studies in the Ajo 1° by 2° quadrangle.
Again, future papers should be forthcoming about the geo-
physics of the area.
REGIONAL GEOLOGY
The regional geology of the Ajo area is described in excellent detail by Gilluly (1946).
that work.
This section is largely based on
For further discussion, the reader is referred to this
and other papers by Gilluly (1937 and 1942).
The Ajo and Sikort Chuapo 15- minute quadrangles consist
mainly of Tertiary volcanics and Quaternary alluvium.
Pre -Cenozoic
rocks crop out dominantly in the Little Ajo Mountains and the Chico
Shunie Hills, west of the town of Ajo.
Figure 3, based on Gilluly
(1946), gives the stratigraphy of the Ajo 15- minute quadrangle and
can be inferred to represent the general stratigraphy of the entire
area.
Figure 4 is a regional geologic map of these two quadrangles
based on Wilson and others (1969).
Stratigraphy
The oldest unit in the area is the Precambrian Cardigan Gneiss.
The unit has a wide variety of rock types within it, ranging from
gneisses through schists with minor pegmatites.
This unit has been
intruded throughout by small bodies of Precambrian hornblendite
that show chilled contacts against the gneiss.
The Cardigan Gneiss
crops out principally in the Gibson Arroyo, west of Ajo.
According to Gilluly (1946), the only Paleozoic rock present
in the region is hornfelsic sandstone, shale and volcanics occuring
as xenoliths in the Chico Shunie Quartz Monzonite, which crops out
11
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11
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Cornelia Quartz Monzonite (main facies)
Cornelia Quartz Monzonite (dioritic facies)
Concentrator Volcanics
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4
3
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Monzonite
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Paleozoic
Unconformity
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ZUnit from Wilson and others, 1969
The Childs Latite, Sneed Andesite and Ajo
Volcanics were combined in Wilson and others,.
1969
Figure 3-- Stratigraphy of the Ajo area (after Billuly, 1946)
5 MIs.ES
ScALt: o:25q000
COFFEEPOT
MOUNTAIN
Figure 4-- Simplified geologic map of the Ajo and Sikort Chuapo 15- minute quadrangles, Arizona (after
See Figure 3 and text for description of units.
Wilson and others, 1969).
P69"
Qa
Tho
TEA
B RTAMOTE
MOUNTRItJS
14
extensively in the southwestern part of the region.
This unit has a
highly variable texture and composition, but the predominant variety
is a coarsely porphyritic quartz monzonite.
Unconformably overlying the basement, the Cretaceous Concentrator Volcanics crop out one to two miles south of Ajo.
This forma-
tion consists of andesitic tuffs, flows and breccias that have been
extensively altered.
No pre- Tertiary rocks crop out in the Sikort Chuapo quad-
rangle (Wilson and others, 1969).
The Laramide Cornelia pluton intrudes the Concentrator Vol -
canics, Cardigan Gneiss and Chico Shunie Quartz Monzonite over much
of the Little Ajo Mountains, several miles west of the town of Ajo.
The pluton is composed of a wide range of distinct facies, many of
which show gradational contacts.
Two units have been separated out
by Gilluly (1946), a border quartz diorite facies, located in the
These
western part of the intrusive, and a quartz monzonite facies.
two units show a sharp contact.
As the description of these rocks
is not the thrust of this discussion, the reader is referred to
papers by Dixon (1966) and Wadsworth (1968) in addition to the papers
by Gilluly and a thesis by Harris (1984) for a more detailed description of these units.
The New Cornelia orebody, which was originally the cupola of
the Cornelia pluton (Wadsworth, 1968) has been downfaulted several
thousand feet by the Gibson fault; it lies south of the town of Ajo
and southeast of the main pluton.
Through 1962 two million tons of
copper had been recovered from 255 million tons of ore and 270 million
15
tons of waste (Dixon, 1966).
Recently, after a short shutdown caused
by the depressed price of copper, Phelps Dodge reopened the New
Cornelia Mine.
The smelter was built in 1950 and is currently not
operating.
Unconformably overlying the Cardigan Gneiss, the Concentrator
Volcanics and the Cornelia Quartz Monzonite in pediments and slopes
to the southeast of the Little Ajo Mountains, the Middle Tertiary
Locomotive Fanglomerate consists of clasts of widely varying composition and grain size.
Boulders up to two feet in diameter are
common, although the average size of the fragments is less than one
inch.
The quality of bedding and degree of sorting increase to the
southeast.
The Middle Tertiary Ajo Volcanics, located west and southwest
of the Ajo Peaks, conformably overlie the Locomotive Fanglomerate and
consist of andesitic breccias, flows and tuffs.
The Middle Tertiary
Sneed Hornblende Andesite conformably overlies the Ajo Volcanics in
the southern part of the Childs Mountain, four miles northwest of
Ajo, and in Copper Canyon in the western part of the Little Ajo
Mountains.
Unconformably overlying the Sneed andesite, the Middle
Tertiary Daniels Conglomerate crops out along the southern flanks of
both Childs Mountain and the Chico Shunie Hills.
The unit consists of
alternating pebbly and sandy layers, with boulders up to four feet
in diameter.
As the two youngest bedrock units in the area are the only
bedrock in the study area, they will be described in much detail
in the following chapter.
Their regional distribution in the Ajo
16
and Sikort Chuapo 15- minute quadrangles will be discussed in this
section.
The only information available to the author on the Sikort
Chuapo quadrangle comes from a geologic map of the State of Arizona
(Wilson and others, 1969).
Owing to the scale of the map, many
Tertiary volcanic units were not distinguished according to their
relative ages and compositions.
The Miocene Childs Latite crops out extensively throughout
southwestern Arizona.
In the Ajo 15- minute quadrangle, the unit
crops out on the western side of Childs Mountain and as a small
patch in the north -central Batamote Mountains.
Within the Sikort
Chuapo quadrangle, intermediate "Pliocene" volcanics (probably the
Childs Latite or its equivalent) compose the eastern part of the
Batamote Mountains, the Pozo Redondo Mountains, south of the Batamote Mountains, and the western part of the Sikort Chuapo Mountains,
east of the Batamote Mountains (Wilson and others, 1969).
The Miocene Batamote Andesite, which was split into three
facies -- extrusive, intrusive and vent --by Gilluly (1946) crops out
extensively in the Batamote Mountains and on Childs Mountain.
It
also crops out in the south -central part of the Ajo 15- minute quad-
rangle and in Black Mountain, four miles south -southeast of Ajo.
The extrusive facies is by far the most abundant.
Outcrops of
vent breccias and the intrusive occur in the northeast part of
Childs Mountain and the central part of the Batamote Mountains; they
probably represent vents from which the Batamote andesite was extruded.
In the Sikort Chuapo quadrangle, "Plio -Pleistocene" basaltic
volcanics (probably the Batamote Andesite) crop out in the eastern
17
part of the Sikort Chuapo Mountains and around Coffeepot Mountain in
the northeastern section of the quadrangle (Wilson and others, 1969).
Two units of alluvium are present within the area.
Plio -
Pleistocene alluvium crops out in several places in the Sikort
Chuapo quadrangle (Wilson and others, 1969).
Quaternary alluvium
fills valleys and occurs as active stream deposits.
Structure
The oldest unit in the area, the Cardigan Gneiss, has undergone
several phases of deformation, the first of which probably occured in
the Precambrian.
The Chico Shunie Quartz Monzonite intruded during
the Mesozoic; both the Cardigan Gneiss and the Chico Shunie Quartz
Monzonite show cataclastic deformation inferred by Gilluly (1946)
to be Mesozoic in age.
The pre- Tertiary rocks were intruded by the New Cornelia
stock in early Tertiary time (Dixon, 1966).
Other Tertiary structure
in the Ajo area is characterized by normal faulting, some of which
is probably related to basin and range tectonism.
The Little Ajo
Mountains are bounded on the northeast and east by the Little Ajo
Mountain and Black Mountain faults, respectively.
The Childs
Mountain fault partially bounds Childs Mountain and the Little Ajo
Mountains on the west.
The Gibson fault has dropped the New Cor-
nelia orebody relative to the quartz monzonite stock.
Other faults
within the Little Ajo Mountains include the Chico Shunie and Ajo
Peak faults ( Gilluly, 1946).
18
The Batamote Mountains have been broken by a northerly to
northeasterly trending set of normal faults in the northwest part
of the range.
detail.
These will be discussed in the next chapter in more
Tertiary faulting in the Sikort Chuapo quadrangle includes
northerly to northwesterly trending normal faults in the Pozo Redondo
and Sikort Chuapo Mountains (Wilson and others, 1969).
The only folding present in the area is gentle warping in the
northern part of the Batamote Mountains (Gilluly, 1946).
In summary, the most important structural features present in
the region, relative to the problem being addressed, are Tertiary
normal faults.
Motion began before the Miocene with early movement
on the Gibson fault and continued into the Holocene.
LOCAL GEOLOGY
The study area was mapped at a reconnaissance scale using
aerial photos.
The results were then compared with earlier maps by
Gilluly (1937 and 1946) and Wilson and others (1969).
Additionally,
contacts and faults were field checked as much as possible.
Two
distinct bedrock units were recognized, the Childs Latite and the
Batamote Andesite, as named by Gilluly (1946).
The Batamote Andesite
has been subdivided into three subunits -- extrusive, intrusive and
vent facies.
Two units of alluvium were observed: an older unit that
forms low, sinuous hills in the north and dissected pediments in
the south, and a younger unit that fills the valleys as active
alluvium.
The stratigraphy and structure of the immediate thesis
area are described in this chapter.
Stratigraphy
The oldest unit in the thesis area is the Miocene Childs
Latite with an age between 17 and 20 million years (May and others,
1980).
Disconformably overlying the Childs Latite, the Batamote
Andesite also has a Miocene age of 15.52 ±0.54 million years (Shafiqullah and others, 1980).
Batamote Andesite.
The two units of alluvium post -date the
The distribution, physiography and petrography
of these units are described below.
19
20
Childs Latite
Distribution and Physiography.
Within the study area, the
majority of the Childs Latite occurs toward the eastern edge.
Small
patches occur in the north -central part and the northwestern part of
the area.
The morthwestern patch is the southeasternmost extension
of the Crater Range.
The Childs Latite tends to form rounded to pointed hills in
the study area; however, on the western flanks of the Sikort Chuapo
In general, this
Mountains, the unit tends to form prominent cliffs.
unit weathers to colors ranging from white to maroon.
Petrology and Mineralogy.
In hand specimen, the Childs Latite
is typically holocrystalline and porphyritic -aphanitic, with white,
glassy, subhedral, medium to coarse grained feldspar phenocrysts in a
pink to maroon, aphanitic groundmass.
However, the grain size and de-
velopment of crystal faces of the phenocrysts varies widely from outcrop to outcrop; in some instances, the feldspar phenocrysts are anhedral
and fine grained.
The unit, in general, shows excellent flow banding.
In addition to the extrusive porphyry, the Childs Latite
contains small outcrops of dikes and breccia.
The dikes have the
same general texture as the extrusive unit, but they are characterized by discordant attitudes relative to the subhorizontal dip of
the unit.
The breccia, which weathers from brown to yellowish
white, consists of coarse to very coarse (0.5 to 50 cm) blocks in a
slightly vesicular, aphanitic matrix.
The blocks are composed of
flow banded, porphyritic -aphanitic Childs Latite.
The breccia crops
out in the northeast in a geographical embayment of latite into the
21
Figure 5 -- Photomicrograph of Childs Latite (under crossed polars).
Note zoned plagioclase and augite phenocrysts (135 X).
22
Batamote Andesite.
In the same area, stratigraphically below the
breccia, the latite has been extensively argillized.
In thin section, the latite shows the same textural variability seen in the hand specimens.
The typical texture is holo-
crystalline, porphyritic -cryptocrystalline to microcrystalline, with
very fine to coarse grained anhedral to subhedral phenocrysts in a
felted cryptocrystalline to microcrystalline groundmass.
The
phenocrysts, which comprise 40 to 60 volume percent of the rock, are
dominated by andesine and /or labradorite (An
orthoclase, magnetite and augite.
) with lesser
to An
40
60
The plagioclase phenocrysts show
marked zoning, with calcic cores that have been locally argillized
to montmorillonite.
Some sections contain partially resorbed,
zoned sanidine and minor biotite.
The groundmass, when its com-
position is distinguishable, consists of plagioclase, augite and
magnetite.
Figúre 5 shows the typical microscopic textures and
mineral compositions of the Childs Latite.
Batamote Andesíte-- Extrusive Facies
Distribution and Physiography.
The Batamote Basaltic Andesite
is the most widespread unit in the study area, and it crops out over
most of the Batamote Mountains.
The extrusive facies makes up the bulk
of the outcrop and forms mesas that have been extensively dissected
by deep canyons.
This facies, in general, dips away from a central
plug located near the high point of the range.
as the volcanic vent.
This is interpreted
23
Petrology and Mineralogy.
The extrusive facies of the Batamote
Andesite occurs dominantly in flows which range in thickness up to 20
The flows show a strong textural zonation, grading from a
meters.
basal gray, fissile rock of aphanitic texture, through an intermediate black, massive, aphanitic section, and finally into a black,
or yellow, while the intermediate and upper units weather maroon or
scoriaceous cap.
black.
The basal unit of a flow typically weathers maroon or
Some sections show flow banding.
Secondary minerals include
zeolites filling amygdules and chalcedony along joints and fractures.
This unit also includes minor volcanic breccia and volcano clastics.
The volcanic breccia, which is probably a result of flow
brecciation, consists of blocks up to 50 cm in a medium to coarse
grained matrix.
The volcanoclastics consist of a medium to coarse
grained, poorly sorted, poorly consolidated wacke.
The minor
lithologies are not described microscopically.
The three textural zones characteristic of the flows are distinctive under the petrographic microscope.
The basal zone is typically
flow banded, holocrystalline and porphyritic -microcrystalline, with fine
grained subhedral to euhedral plagioclase and olivine phenocrysts in a
felted, pilotaxitic microcrystalline groundmass consisting of plagioclase laths.
Some sections had glass in the groundmass.
The intermediate zone is characteristically hypocrystalline,
porphyritic -microcrystalline or vitric, with fine grained, subhedral
mafic phenocrysts in a pilotaxitic, microcrystalline plagioclase
groundmass or a black hyaloophitic groundmass of microcrystalline
plagioclase laths and glass.
24
Finally, the upper zone is scoriaceous, hypocrystalline,
porphyritic - vitric with one or two sizes of phenocrysts in a vitric
groundmass.
The larger phenocrysts consist of fine grained subhedral
to euhedral olivine crystals, whereas the smaller phenocrysts are
typically plagioclase microlites.
Figures 6 and 7 show typical
textures and mineralogies of the basal and upper zones of the flows.
Although the texture varies widely within the flows, the
mineralogy remains relatively constant.
The coarsest phenocrysts in
all thin sections are olivine grains that have been partially to
completely replaced by iddingsite.
Plagioclase occurs both as
phenocrysts and microlites within the groundmasses.
tions ranging from sodic andesine (An
)
It has composi-
to calcic labradorite
36
(An
); more typical anorthite contents range from 45 to 60 %.
Magnetite is a common accessory mineral, while hypersthene and augite
occur infrequently.
Batamote Andesite- -Vent Facies
Distribution and Physiography.
The vent facies of the Bata -
mote Andesite occurs in the central part of the study area just
southwest of the high point of the Batamote Mountains.
This facies
crops out on the periphery of, or stratigraphically above, the intrusive facies.
The unit forms outcrops that stand out relative to the
surrounding rocks.
Petrology.
The vent facies is a red to maroon oxidized
volcanic breccia that consists of blocks ranging in size from 10 cm
to 1 m in an aphanitic to coarse grained matrix.
The easternmost
25
Figure 6 -- Photomicrograph of the basal section of a typical flow,
Batamote Andesite (under crossed polars). Note plagioclase and
olivine phenocrysts in felted, pilotaxitic microcrystalline
groundmass (135 X).
26
Figure 7-- Photomicrograph of the upper unit of a typical flow,
Batamote Andesite (under crossed polars). Note two sizes of phenocrysts in hyaloophitic groundmass (135 X)..
27
outcrop has a sub -horizontal, sedimentary -like bedding up to 2 m
thick.
This facies was not described microscopically.
Batamote Andesite -- Intrusive Facies
Distribution and Physiography.
The intrusive facies of the
Batamote Andesite crops out in a one square mile area in the central
part of the study area southwest of the high point of the range.
The facies has no distinctive topographic expression.
Petrology and Mineralogy.
The Batamote intrusive can be
subdivided into two distinct units, a fine grained, equigranular
diorite (or gabbro ?) in the south and a dense, massive porphyritic-
aphanitic basaltic andesite in the north.
The nature of the con-
tact between the two phases was not determined.
In hand specimen, the diorite is holocrystalline, hypidiomorIn out-
phic- granular, fine grained with a salt and pepper texture.
crop, the unit, which weathers gray to reddish -yellow, is massive
towards the center and grades outwards into an outer zone that is
highly jointed.
In thin section, the diorite has a grain size ranging from
0.3 to 1 mm.
It is dominated by andesine (An
) with
to An
40
50
accessory olivine (that has been altered extensively to iddingsíte),
magnetite and minor intergranular augite and hypersthene.
The
olivine /iddingstie crystals have a slightly larger grain size than
the other crystals.
this unit.
Figure 8 shows the textures and mineralogy of
28
The porphyritic -aphanitic unit, which composes the bulk of
the intrusive, weathers yellow on outcrop.
Towards the center of the
intrusive, the phase develops two roughly perpendicular sets of
vertical joints.
developed.
Towards the edges, this jointing is less well
At the edges, the unit interfingers extensively, or
grades into, the vent facies described earlier.
This unit is holocrystalline, porphyritic- cryptocrystalline
to microcrystalline, with subhedral to euhedral fine grained
(0.3 to 1 mm) phenocrysts in a cryptocrystalline to microcrystalline
groundmass.
The phenocrysts are composed of olivine that has been
altered slightly to iddingsite; the groundmass, when distinguishable,
consists of andesine to labradorite (An
thene, magnetite and augite.
) with lesser hypers-
to An
45
60
In this unit, the hypersthene predomin-
ates over the augite, whereas in the dioritic unit, augite predominates over hypersthene.
Figure 9 shows the textures and mineralogy
of this phase of the intrusive.
In summary, the intrusive facies of the Batamote Andesite has
two distinct units:
a diorite and a basaltic andesite.
The rela-
tionship between the two units was not determined.
Older Alluvium
This alluvium, which is younger than the Batamote Andesite,
consists of pebbles and cobbles in an unconsolidated fine sand to
silt matrix.
In the northwest, the unit forms low (3 m), sinuous
hills on the outwash plain north of the Batamote Mountains; the
pebbles and cobbles are composed of Batamote Andesite.
On the other
29
Figure 8 -- Photomicrograph of the dioritic unit of the intrusive
facies of the Batamote Andesite (under crossed polars). Note the
relative coarse granularity of the unit (135 X).
30
Figure 9-- Photomicrograph of the porphyritic unit of the intrusive
facies of the Batamote Andesite (under crossed polars) (135 X),
31
hand, in the southeast, the unit forms a dissected pediment and the
pebbles and cobbles consist of Childs Latite.
Quaternary Alluvium
The valleys and active stream channels are filled with an
unconsolidated gravel with cobbles and pebbles in a sandy to silty
matrix.
In places, the alluvium has been cemented by extensive
caliche.
Structure
Deformation within the study area is limited to normal
faults in the Batamote Andesite and minor warping of both the Childs
Latite and the Batamote Andesite.
Since there are no marker beds
in the study area, the structure in the area is largely conjectural,
and is based on topography and aerial photographs.
Faulting
The only faults present are located in the northwest.
Although inferred from aerial photographs, they agree well with
those reported by Gilluly (1946).
observed along one fault trace.
Additionally, fault gouge was
However, due to the lack of marker
beds, the displacement of the faults could not be determined.
The
fault as shown by Wilson and others (1969) to pass through the center
of the range, was not observed in the field.
Folding
Gilluly (1946) reports relatively minor warps within the
Batamote Andesite; however, the majority of the attitudes in this
32
unit are depositional.
During reconnaissance mapping, an anticline
was observed in the Childs Latite in the northeastern embayment
into the Batamote Andesite.
Alteration
In view of the geochemical anomalies derived from it, the
Batamote Andesite is notable for its lack of significant alteration.
The only secondary minerals present in the unit are amygduloidal
zeolites, and joint and fracture filling chalcedony.
However, a
"limonite" multispectral imaging anomaly occurs around the Batamote
plug (Gary Raines, U.S. Geological Survey, personal communication,
1984)
.
On the other hand, an extensive zone of alteration was observed in the Childs Latite in the northeastern embayment of this
unit into the Batamote Andesite.
strongly argillized.
In this area, the unit has been
LITHOGEOCHEMISTRY
A total of 58 rock chip samples were collected within the
study area, pulverized and analyzed for 31 elements using semi quantitative emission spectro -scopy (Grimes and Marranzino, 1968).
The
results of these analyses are given in Appendix Ia, while their
locations are given in Plate 2.
Of these samples, 41 came from the
extrusive facies of the Batamote Andesite, three came from the intrusive facies of the Batamote Andesite, five came from the Childs
Latite, and six samples came from other rock types, including chalcedony, caliche and volcanoclastics.
In addition, Gilluly (1946) and
Jones (1974) presented major element oxide analyses for Childs Latite
and Batamote Andesite within the region.
In this chapter, the analyses of the major and minor oxides
from other studies are reviewed, and the distribution of trace elements
in the Batamote Andesite and Childs Latite, especially copper, lead
and zinc, are discussed.
Major and Minor Elements
Gilluly (1946) reported analyses of rocks for 18 oxides and
sulfur, and Jones (1974) reported analyses for nine oxides.
results of these two studies are summarized in Table 1.
The
The analyses
indicate that the Childs Latite and the Batamote Andesite have
essentially the same concentrations of silica, alumina, ferric oxide,
soda and titanium oxide.
On the other hand, the Batamote Andesite
33
34
has significantly higher concentrations of ferrous oxide, magnesia
and lime, while the Childs Latite has higher concentrations of
potash.
The most marked difference is in magnesia, where the con-
centration in the Batamote Andesite is more than twice that of the
Childs Latite.
The mineralogy of these two rock types reflects the difference in their composition.
The presence of olivine as the predomin-
ant mafic mineral in the Batamote Andesite reflects the high magnesia
content, while the presence of orthoclase and sanidine in the Childs
Latite reflects its higher potash content.
Based on the relatively
high silica concent, Gilluly (1946) classified the Batamote Andesite
as an andesite, although he said true basalt flows may occur within
the Batamote Mountains.
Table 1-- Summary of major element oxide analyses of the Childs Latite
and the Batamote Andesite (after Gilluly, 1946 and Jones, 1974)
Oxide
Childs Latitel
Range
Mean
Batamote Andesite2
Range
Mean
Si02
55.52
53.00-57.65
55.93
49.06-59.88
A1203
16.08
14.56-18.14
16.33
15.69-17.33
Fe203
4.70
2.29-5.61
4.09
3.10-5.38
Fe0
2.58
1.65-4.07
3.78
1.41-6.37
Mg0
1.73
0.52-3.22
4.14
2.74-6.17
Ca0
5.37
4.42-6.38
7.03
5.31-8.95
Na20
3.98
3.40-4.39
3.41
3.11-3.62
K20
3.80
2.36-4.27
2.22
1.52-3.25
TiO2
1.20
0.79-1.55
1.05
0.79-1.40
All values in weight percent.
1Four samples from Gilluly (1946) and four samples from Jones (1974)
2Five samples from Gilluly (1946)
35
The results of the semi -quantitative analyses for elements
that had greater than 75% unqualified values are summarized in Table
2.
For statistical analysis, qualified values were assigned values
one and one -half of a spectrographic step below the detection limit
for "N" (not detected), and "L" (detected at levels below the detection limit), respectively.
Because of the small population for the
Childs Latite, the standard deviations are not given.
The semi -
quantitative nature of the data in Table 2 should be remembered.
The major and minor elements, as determined by semi- quanti-
tative emission spectroscopy, show the same relative abundances by
rock type as the oxide analyses.
The Batamote Andesite has higher
concentrations of iron, magnesium, calcium, titanium and manganese.
For the Batamote Andesite, all major and minor elements have relatively
low standard deviations relative to their means.
Only calcium has
a relatively high standard deviation.
Trace Elements
Trace elements are defined as elements that have abundances
of less than 0.1 percent (Levinson, 1980).
Table 2 have this characteristic.
Fourteen elements in
Of these, two (B and Be) have
significantly higher concentrations in the Childs Latite, which
probably reflects the more felsic nature of this unit.
On the other
hand, seven elements (Co, Cr, Cu, Ni, Sc, Sr and V) have higher
concentrations in the Batamote Andesite, which reflects its more mafic
nature.
Four elements (La, Pb, Y and Zr) have approximately the
same concentration in these two rock types.
Barium proved to be
36
Table 2 -- Summary of emission spectroscopic analysis on the Childs
Latite and Batamote Andesite
Batamote Andesite
Standard
Deviation
Mean
Childs Latite
Range
Element
Range
Mean
Fe (%)
0.3-2
1.1
2 -7
4.5
1.2
Mg (%)
0.2-1
0.48
1 -2
1.3
0.4
Ca (%)
0.2-1.5
0.82
1.5 -10
1.9
1.3
Ti (%)
0.03-0.3
0.12
0.2 -0.7
0.44
0.11
760
1000 -2000
1200
330
42
10-50
19
7
630
180
Mn
700-1000
B
20-70
Ba
50-500
Be
N(5)-10
Cr
N(10)
Cu
L(5)-10
Ni
N(5)-20
Pb
10-30
0.3
1.4
10-30
20
7
5
10-150
34
29
6
15 -50
28
10
50 -100
82
21
10 -70
28
18
10 -30
19
5
500
0
3.8
50-100
300-1000
L(1)-2
4.7
1-7
Co
La
190
72
5.6
20
190
500
Sr
N(100)-500
V
N(10)-50
23
50 -100
86
17
Y
20-30
22
10 -50
34
12
Zr
50-200
199
58
110
50 -300
Replacement values for qualified values
Element
Qualified Value
Element
Qualified Value
N
L
Ni
2
3
3
Sc
2
3
5
7
Sr
50
70
2
3
V
5
7
N
L
Be
0.5
0.7
Co
2
Cr
Cu
Values in parts per million unless otherwise indicated.
37
unusual in that it has higher concentrations in the andesite; yet,
in general, it is concentrated in more potassium -rich rocks (Levinson, 1980).
Therefore with the exception of barium, major, minor and
trace elements conform to the expected relative abundances of the two
rock types.
As this study is concerned with the concentration of copper,
the distribution of base metals in the Batamote Andesite is important
to later interpretations.
Figures 10 through 12 are histograms
showing the distributions of values of copper, lead and zinc, respectively, in the extrusive facies of the Batamote Andesite.
Copper values have a restricted range of values characterized
by one mode at 30 ppm, indicating that the Batamote Andesite has a
relatively even distribution of copper.
Moreover, because the average
abundance of copper in andesite is 55 ppm (Wedepohl, 1969) the Batamote
Andesite is somewhat depleted in copper relative to other rocks of
similar composition.
Lead has a similar restricted range of values around 20 ppm,
which is enriched relative to the 5.8 ppm average abundance in andesite (Wedepohl, 1969).
Zinc has an irregular distribution with values
up to 1000 ppm, but clustering around L(200).
This distribution
indicates that zinc has a higher than average abundance relative to
andesite at 70 ppm (Wedepohl, 1969).
R -Mode Factor Analysis
R -mode factor analysis was performed on 41 samples from the
extrusive facies of the Batamote Andesíte, as this is the most
38
important rock in the study area.
All elements, except strontium,
that had greater than 75% unqualified values using semi- quantitative
emission spectroscopy (18 total) were used in this analysis.
Quali-
fied values were assigned numerical values as in earlier statistical
treatments of the data.
Strontium was not used because it had no
variance over the sample population.
The exact method used was
principal factoring with iterations and varimax rotation (c.f. Nie
and others, 1974).
The results of the factor analysis are given in
Table 3, and a graphical depiction of the factor loadings (which
represent both correlation coefficients and regression weights between the elements and the factors) is given in Figure 13.
Four initial factors with eigenvalues greater than one (i.e.
the factor explains a greater amount of the total variance than is
explained by a single element), explained 70.5% of the total variance
within the data.
The other 14 initial factors explained 29.5% of
the variance.
When terminal factors were determined by iteration, the first
two factors accounted for 81.0% of the total variance.
The other two
terminal factors explained less than 20% of the variance; they have
much less importance than the first two factors.
Low communalities
(less than 0.5) for titanium and boron imply that the four terminal
factors do not explain the variance of these elements well; other
factors played a greater role in determining their concentrations.
Factor 1 probably represents the mafic component of the
Batamote Andesite; it corresponds very well with the ferride assemblage of Theobald and Barton (1983).
High positive factor loadings
39
VALUE
FREQUENCY
(PPM)
5
10
15
20
N(5)
L(5)
5
7
10
15
20
30
50
figure 10 -- Histogram showing the distribution of copper in the Batamote
Andesite
FREQUENCY
VALUE
(PPM)
O
5
10
15
20
25
30
N(10)
L(1O)
10
15
20
30
Figure 11 -- Histogram showing the distribution of lead in the Batamote
Andesíte
40
FREQUENCY
VALUE
(PPM)
0
5
10
15
20
25
30
N(200)
L(200)
200
300
500
700
1000
Figure 12 -- Histogram showing the distribution of zinc in the Batamote
Andesite
41
Table 3-- Results of R -mode principal factor analysis with iterations
after varimax rotation for the extrusive facies of the Bata -
mote Andesite, Batamote Mountains, Arizona
Element
Communality
Factor 1
Factor Loadings
Factor 3
Factor 2
Factor 4
0.66560
0.61128
0.75973
0.38460
0.55794
0.78658
0.67672
0.04594
0.33886
0.17178
0.18030
-0.32253
-0.07245
0.51152
0.18675
0.02773
0.21855
-0.03935
0.00967
0.70138
0.11667
-0.03932
0.86650
0.08959
0.04017
Co
Cr
0.19663
0.39957
0.61659
0.72540
0.70063
0.24489
-0.10538
-0.19760
0.78461
0.62398
0.28708
0.52316
0.70325
-0.10914
-0.55629
-0.22155
0.30878
0.24807
0.30995
0.04274
0.07184
0.13938
-0.14645
0.04253
-0.00172
Cu
La
Ni
Pb
Sc
0.51839
0.82499
0.92211
0.66127
0.73552
0.42356
0.04252
0.82012
-0.02951
0.76293
0.13340
0.86665
-0.47226
0.71231
0.17019
0.56102
-0.13663
0.15327
0.39013
0.12324
-0.08020
-0.23114
-0.05122
-0.03104
0.33062
V
Y
0.68194
0.69455
0.64201
0.80772
0.36794
-0.13381
0.11867
0.59870
0.78843
-0.10038
0.22903
0.02032
-0.07330
0.38508
0.04560
Fe
Mg
Ca
Ti
Mn
B
Ba
Be
Zr
Factor
1
2
3
4
Eigenvalue
4.93591
4.22015
1.12328
1.01915
Percent of Variance
43.7
37.4
9.9
9.0
Cummulative Percent
43.7
81.0
91.0
100.0
Zr
Pb
Cu
g
Bç
Ba
La
Mn
Y Ti
Sc
B
Cu
Fe
Mn
FACTOR 2
Cu
-- B
Ti
Ca
La v
CrSc
Fe
Zr
NiM9
Pb
-Co
BaBe
Mn
FACTOR 3
Ti
Ba
gNi
Cu
geLa
V
M Pb
Zr
CoMn
B
Fe
Sc
FACTOR 4
Figure 13 -- Factor loadings for 18 elements from R -mode factor analysis of the Batamote Andesite
-1.0
0.0
Co
Mg
-Cu
Cr
Sc
-V
Fe
Ni
FACTOR 1
1.0T
43
clearly group elements with a mafic association (Ni, V, Fe, Co,
Sc, Mg and Cr).
Additionally, elements with a felsic association
(e.g. Be, Zr, Pb and La) tend to have either a low or negative
factor loading.
Conversely, factor 2 probably has a felsic or intermediate
association.
In this case three groupings of elements can be seen:
a group with high positive loadings (La, Zr, Pb, Be, Y, Ba and Ti), a
group with low absolute factor loadings (B, Mn, Fe, Sc, Cu, V,
Ca and Co), and a group with high negative loadings (Mg, Ni and
Cr).
With the exception of titanium, the elements in the first
group --the group that defines the factor --all have a felsic or
intermediate association; the elements in the third group --which
has a negative correlation with the factor --have a more mafic
association.
This factor, therefore, seems to be positively correl-
ated with the intermediate to felsic component of the rock.
The nature of the other two factors is much less straightforward.
Factor 3 separates manganese and copper, with relatively
high factor loadings, from the rest of the elements.
Possibly this
factor could be associated with the copper anomalies discussed later
in this report.
Factor 4 separates calcium and possibly yttrium
and scandium from the other elements.
It could represent calcite -
filled amygdules or the effect of caliche on the samples.
Both
these factors account for relatively little variance (less than
10% each).
STREAM SEDIMENT GEOCHEMISTRY
A total of 101 stream sediment samples were collected from
89 sites.
The samples were collected in three phases: 1. A pre-
liminary phase to check the anomalies observed by Barton and others
(1982); 2. The main phase to define the distribution of copper; and
3. Follow -up work to determine the changes in the concentration of
copper upstream along anomalous drainages.
Sample locations, along
with the drainage patterns and areas of influence of the samples,
respectively, are given in Plates 3 and 4.
The samples were analyzed
using semi- quantitative emission spectroscopy (Grimes and Marranzino,
1969; E.F. Cooley, U.S. Geological Survey, personal communication,
1983), a hot nitric acid leach (modified after Ward and others, 1969)
The results of the semi -
and two sequential extraction techniques.
quantitative emission spectroscopic analysis are presented in Appendix
Ib; the analytical methods are described in Appendix II; and the
results of the chemical analyses are given in Appendices IIIa through
IIIb.
Preliminary Phase
To confirm the results of the survey by Barton and others
(1982) and to check the possibility of contamination from the Ajo
smelter, seven stream sediment samples were collected in December
1982.
Of these, two (AJ001S and AJ002S) came from washes that
drained the Valley of the Ajo, which lies between the smelter and
44
45
the area of interest, while the others drained the Batamote Mountains.
Using nylon and aluminum screens, five size fractions were
sieved and then pulverized to -200 mesh.
The size fractions are:
-30 mesh ( <600 pm), 30 mesh to 80 mesh (600 pm to 180 pm), 80 mesh
to 150 mesh (180 pm to 100 pm), 150 mesh to 200 mesh (100 pm to
75 pm), and -200 mesh ( <75 pm).
Each size fraction was analyzed
for copper with atomic absorption spectrophotometry using a hot
nitric acid leach (see Appendix II).
The results of this analysis
are given in Table 4.
The results of this preliminary phase indicate that the
anomalies described by Barton and others (1982) are real, that airborne smelter contamination is not significant, and that -30 mesh
stream sediment is perfectly adequate for more detailed work.
The values of 100 to 190 ppm copper in the -30 mesh fraction
correspond nicely with the anomalous values ranging from 100 to 200
ppm copper reported by Barton and others (1982).
Consequently,
further work was justified.
Smelter contamination was considered unlikely at the end of
this phase of the study for two reasons.
First, high values persist
on the eastern (downwind) side of the Batamote range.
Samples
AJ003S, AJ005S and AJ007S came from this area; their values remain
anomalous, especially in light of the background values of copper
in the Batamote Andesite.
Additionally the intensity of the anomaly
does not increase significantly on the west side of the range as
might be expected with airborne contamination.
46
Table 4-- Concentrations of copper in selected stream sediment samples
relative to particle size
Sample
-30
Size Classes (U.S. Standard Mesh)
-150/ +200
-301+80
-80/ +150
-200
AJ001S
170
190
190
160
230
AJ002S
90
60
30
140
170
AJ003S
140
120
120
160
290
AJ005S
120
120
120
120
160
AJ007S
110
120
130
140
190
AJ008S
190
170
200
210
260
AJOlOS
130
110
130
170
220
Second, high copper values are present in the coarsest
fractions of the samples.
For a typical smelter, 50% of the smelter
dust passes through a 400 mesh screen, and 80% of the dust passes
through a 150 mesh screen.
communication, 1984).
(E. Partelpoeg, Phelps Dodge, personal
Therefore, barring sorption, airborne contam-
ination would be important only in the finest fractions.
Although
the concentrations of copper increase with decreasing grain size
(which is expected anyway), the presence of anomalous values in the
-30/ +80 mesh fraction argues against airborne smelter contamination.
Additionally, the results of later work also argue against this
mechanism.
Finally, the -30 mesh size fraction proved to give adequate
values and reasonable contrast.
Therefore to minimize effort in
sample preparation and to decrease problems with eolian transport
and contamination, the -30 mesh size fraction was chosen for further
work.
47
Main Phase
The second phase of stream sediment collection involved
sampling 78 sites at a sampling density of 0.89 samples /tang to
determine the distribution of copper in the Batamote Mountains.
Each of the preliminary sample sites in the mountains was resampled;
replicate samples were collected at seven additional sites.
Repli-
cate stream sediment sample pairs are listed in Table 5:
Table 5-- Replicate stream sediment sample pairs
AJ003S- AJ036S
AJ010S- AJO3OS
AJ096S- AJ097S
AJ005S- AJO11S
AJ083S- AJ084S
AJ098S- AJ099S
AJOO7S- AJ021S
AJ087S- AJO88S
AJ1O3S- AJ104S
AJOO8S- AJO29S
AJ091S- AJ092S
AJ105S- AJ106S
Field Methods
At each sample site, stream sediment and heavy mineral concentrate samples were collected.
Sediment, composited along a 100
foot reach of channel, was screened through a 5 mm sieve in the field.
Between 400 and 1600 g (usually 500 to 1000 g) of -5 mm sediment was
collected as a stream sediment; between 1500 and 3500 g (usually
2000 to 3000 g) were collected as a heavy mineral concentrate.
Sample Preparation
In the laboratory the stream sediment samples were sieved
to -30 mesh and split.
mesh.
Between 30 and 80 g were pulverized to -200
The rest was saved for later investigations.
material was discarded.
The +30 mesh
48
Results of the Hot Nitric Acid Extraction
All samples were analyzed for copper using atomic
absorp-
tion spectrophotometry with a hot nitric acid extraction (see
Appendix II for technique).
The extraction solubilizes all adsorbed
ions and most common sulfides and oxides.
However, it is not total
because silicates are not attacked to a significant degree (Ward
and others, 1969).
The results (see Appendix IIIa) of this analysis suggested a
bimodal frequency distribution, with one mode at 75 ppm and the other
mode at 150 ppm (see Figure 14).
Two anomalous areas (defined using
a threshold of 100 ppm) separated by a trough of lower values occur
in the northwest and north -central parts of the study area (see
Plate 5).
The values trail off to the east and southeast to values
around 50 ppm.
The northwestern anomaly (which has values up to 280 ppm) has
a strong spatial association with the northerly trending normal
faults described earlier in this paper.
However, the easternmost
fault in this group lies within the trough of low copper values.
The north -central anomaly (which has values up to 150 ppm)
has no obvious structural or lithological control.
Conceivably,
it could be a continuation of the northweatern anomaly.
In fact,
later analyses tend to support this hypothesis.
Results of Semi -Quantitative Emission Spectroscopic Analysis
Each sample was analyzed for 31 elements using semi- quanti-
tative emission spectroscopy (Grimes and Marranzino, 1969) modified
49
RANGE
(PPM)
FREQUENCY
0
5
10
15
20
1- 25
26- 50
51- 75
76-100
101 -125
126 -150
151 -175
176 -200
201 -225
226 -250
251 -275
276 -300
3
3
Figure 14 -- Histogram showing the distribution of copper (extracted
using hot nitric acid) in -30 mesh stream sediments
50
to lower the detection limits of certain elements (Ag, As, Au,
Be, Bi, Cd, Cu, Pb, Sb, Sn, W and Zn; E.F. Cooley, personal communication, 1983).
The results (see Appendix Ib) indicated anomalous
areas in the northwest and north -central part of the study area
characterized by highs of copper, silver and bismuth.
Copper.
The results of semi -quantitative emission spectro-
scopic analysis of copper, an analysis for total copper, are similar
to the results for the hot nitric acid extraction.
Both procedures
show a bimodal frequency distribution and similar areal distributions.
In fact, the two procedures have a correlation coefficient of 0.8185
based on 92 samples.
Therefore, owing to the high variance inherent
in semi -quantitative emission spectroscopy, only the results for the
nitric acid extraction are presented graphically in this paper.
Silver and Bismuth.
pattern observed in copper.
Both silver and bismuth mimic the anomaly
Figures 15 and 16 and Plates 6 and 7
show the frequency and areal distributions of silver and bismuth,
respectively.
High silver values (greater than or equal to L(0.1))
have a wider distribution than the high copper values, yet they occur
in the same general areas.
Bismuth shows a distribution that has
a better visual correlation with copper than silver.
A trough of
low values, corresponding with the one for copper, also appears in
the bismuth map; the trough is not apparent on the silver map.
As
the values reported are right at the detection limit (especially for
bismuth), the true backgrounds for these two elements could not be
determined.
51
FREQUENCY
VALUE
(PPM)
0
5
10
15
20
25
30
35
N(0.1)
L(O.1)
0.1
0.15
0.2
0,3
0.5
0.7
1
Figure 15 -- Histogram showing the distribution of silver (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
VALUE
(PPM)
0
5
10
FREQUENCY
30
25
40
45
N(2)
L(2)
2
Figure 15 -- Histogram showing the distribution of bismuth (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
52
Silver is a chalcophile element that is typically associated
with copper in "red bed" sandstone deposits and some porphyry copper
deposits.
Crustal abundance averages 0.07 ppm and ranges from 0.04
ppm in felsic rocks to 0.1 ppm in mafic rocks (Levinson, 1980).
For intermediate igneous rocks, average abundance is 0.07 ppm (Wedepohl, 1969).
It has a high mobility in the primary environment,
but is only slightly mobile in oxidizing, acid and gley secondary
environments (Levinson, 1980).
Consequently, the association of sil-
ver with copper is not unusual; however, the lower values of silver
are near the background for andesites.
A chalcophile element, bismuth has a crustal abundance of
0.17 ppm, which implies that the observed anomaly of 2 ppm is significant.
The abundance of bismuth varies from 0.1 ppm in felsic rocks
to 0.15 ppm in mafic rocks.
metallic deposits.
Bismuth can occur with copper in poly -
Although its mobility in the primary environment
is high, it has a very low mobility at the surface, commonly precipitating with iron oxides (Levinsion, 1980).
However, relatively
little is known about the detailed geochemical behavior of this
element.
Within the Ajo 1° by 2° quadrangle, bismuth has an association
with the Precambrian.
It best characterizes a "half- moon" shaped
Bi -Pb -Mo anomaly, centered over a magnetic bullseye (possibly indi-
cating a shallow intrusive) in the presumed Precambrian of the
Mohawk Range, northeast of the study area (P.K. Theobald, U.S. Geological Survey, personal communication, 1984).
Elsewhere in
southern Arizona bismuth has been observed in pegmatites and is
53
associated with pyrometasomatic deposits in the Pima District
(Cooper, 1962).
Other Base Metals.
Plate 8 shows the distribution of anomal-
ous values of molybdenum, lead, tin and zinc in -30 mesh stream sediment.
Figures 17 through 20 show the frequency distributions for
the same elements.
Of these, only anomalous values of tin (ranging
from L(5) to 10 ppm) seem to be associated with the copper- silverbismuth anomaly.
The anomalous values of molybdenum, lead and zinc
occur in no recognizable systematic way throughout the study area.
This, in combination with the relatively low values of the anomalies,
suggests that they are not significant.
R -Mode Factor Analysis.
R -mode factor analysis was performed
on the stream sediment data using the same criteria and methodology
described earlier in the chapter on lithogeochemistry (replacements
of qualified data were different as different lower detection limits
were used).
In this case, strontium was used in the analysis be-
cause it had siggíficant variance.
The results of the analysis are
given in Table 6 and graphically depicted in Figure 21.
Five initial factors with eigenvalues greater than one
accounted for 67.5% of the total variance.
Fourteen other initial
factors accounted for 32.5% of the total variation.
After transformation to terminal factors, the first factor
explained 59.8% of the variance - -by far the dominant factor.
other factors each explained 15.6% or less of the variance.
The
So in
this case there is one dominant factor and four lesser factors.
54
FREQUENCY
VALUE
(PPM)
0
5
10
70
75
N(5)
L( 5)
5
7
10
3
Figure 17 -- Histogram showing the distribution of molybdenum (analyzed
using semi- quantitative emission spectroscopy) in -30 mesh
stream sediment
FREQUENCY
VALUE
(PPM)
0
5
10
15
20
45
50
N(2)
L(2)
2
3
5
7
10
15
20
30
50
70
100
150
200
300
J
7
Figure 18 -- Histogram showing the distribution of lead (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
55
VALUE
(PPM)
0
FREQUENCY
70
10
5
75
N(5)
L(5)
5
7
10
Figure 19 -- Histogram showing the distribution of tin (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
FREQUENCY
VALUE
(PPM)
0
5
10 6 0
N(50)
L(5O)
l
50
70
J
Figure 20-- Histogram showing the distribution of zinc (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
56
Table 6 -- Results of R -mode principal factor analysis with iterations
after varimax rotation for -30 mesh stream sediments, Batamote
Mountains, Arizona
Element
Communality
Factor 1
Factor Loadings
Factor 2 Factor 3 Factor 4
Factor 5
0.74229
0.74964
0.26428
0.91213
0.46846
0.69705
0.84115
0.18574
0.35775
0.60964
0.33028
0.12003
-0.07881
0.83552
0.15351
0.31758
0.05638
0.39103
0.25571
0.01800
0.18934
-0.07092
0.14340
0.09664
0.21378
0.10304
0.13959
0.22382
0.01646
0.16494
0.41485
0.68883
0.28242
0.76290
0.73356
-0.51733
0.39648
-0.37576
0.80419
0.72339
-0.05579
0.48920
0.00893
0.32809
0.12224
-0.21456
0.08998
0.15277
0.07367
-0.29935
-0.20552
0.53036
-0.29445
-0.03520
-0.23905
-0.23630
-0.05418
0.17634
0.04324
0.22038
Sc
0.54530
0.32292
0.54275
0.31048
0.90160
-0.22608
-0.16380
0.63838
-0.07723
0.85625
-0.05215
0.14914
0.22980
0.04165
0.07096
-0.26265
0.37634
-0.20687
-0.04738
0.36210
-0.07471
0.33595
-0.04416
0.54749
-0.14707
-0.64568
0.13910
0.20535
0.02800
-0.10332
Sr
V
Y
Zr
0.59892
0.46831
0.47772
0.36704
0.44652
0.45452
-0.01590
-0.05413
0.30450
0.46389
0.11381
-0.03312
0.33982
-0.17469
0.65063
0.00217
0.38647
0.12519
-0.20183
0.01597
0.20490
0.01850
0.02171
-0.60229
Fe
Mg
Ca
Ti
Mn
B
Ba
Be
Co
Cr
Cu
La
Ni
Pb
Factor
1
2
3
4
5
Eigenvalue
6.31778
1.64818
1.15515
0.84477
0.59299
Percent of Variance
59.8
15.6
10.9
8.0
5.6
Cummulative Percent
59.8
75.4
86.4
94.4
100.0
Fe
Co
Sc
Pb
Y
Be
B
-Cu
La
Zr
Ca
.
Pb
Ca
Cu
Sc
gC r
M_
Mnn
La
Sc
Fe Co
Ba
-Ti
Ba
Ti
V
-Mn
Ni
Cr
Mg
FACTOR 2
La
Y
Cr
V
Sr
-B
Cu
Ni
Pb
Mñ g
oBa
Be
Sc
-Sr
FeTi
a
FACTOR 3
Be
B
Sc
CuMg
Co
Mn
Ca
Sr
Pb
ZrTi
La
Ba
FACTOR 4
Fe
La
Co
Be
Mg
Ni
Ca
Ba
Y
Mn
Sr
Cr
FACTOR 5
Figure 21-- Factor loadings for 19 elements from R -mode factor analysis of stream sediments
-1.0
0.0
1.0
FACTOR 1
58
As with the bulk rock analysis, the dominant factor is relatively easy to explain, but the four lesser factors are problematic.
Factor 1 in stream sediments has relatively high loadings for
scandium, magnesium, cobalt, chromium, iron, nickel and manganese,
with possible associations of vanadium, strontium and barium.
As
with factor 1 in the bulk rock analysis, most of the elements with
high loadings are associated with mafic rocks.
Additionally, boron
and beryllium, elements associated with felsic rocks, have high
negative loadings, indicating a negative correlation with the factor.
Therefore, factor 1 probably reflects the mafic component of the
Batamote Andesite, which crops out in the majority of the sampled
area.
It also corresponds to the ferride factor of Theobald and
Barton (1983).
Factor 2 is characterized by high factor loadings for titanium,
barium and vanadium; factor 3 has high loadings for yttrium, and
possibly calcium, lanthanum, scandium, strontium, iron and titanium;
factor 4 has high loadings for lead, barium, strontium and lanthanum;
and factor 5 has high negative loadings for copper and zirconium.
Of these, only factor 5 has meaning in context of this study.
In it, copper and zirconium are the controlling elements, with some
possible contribution from boron.
separated from the other elements.
These three elements are distinctly
Both boron and zirconium are
weakly correlated with copper (correlation coefficients are 0.4466
and 0.4153, respectively).
Also high values of boron and zirconium
do occur in the anomalous areas as defined by copper.
Therefore,
59
this factor might reflect the mechanism that produced the anomalous
values observed.
The factors with obscure explanations could represent contributions to the sediment from a single mineral or suite of minerals.
Factor 2 could represent rutile and other titanium oxides and hydroxides; factor 3 could represent the presence of xenotime or monazite
(thorium was found in the non - magnetic fraction of heavy mineral
concentrates); and factor 4 could relate to the presence of potassic
feldspar as lead, barium and strontium are common trace elements
in this mineral.
In the final factor solution, the five factors explained
less than 50% of the variance for calcium, manganese, boron, beryllium,
lanthanum, lead, vanadium, yttrium and zirconium.
several other elements have low communalities.
Additionally,
Therefore many other
factors are required to explain the variance beyond the five terminal
factors generated.
Results of the First Sequential Extraction
To determine the mineralogic distribution of copper within
the stream sediment samples, two sequential extractions were performed.
The first, which was performed on one sample from each site, involved
three steps.
First, hot oxalic acid was used to remove the "oxide"
fraction (T.T. Chao, U.S. Geological Survey, personal communication,
1983).
Then a combination of potassium perchlorate and cold hydro-
chloric acid was used to remove the "reduced" (i.e. sulfide and
organic) fraction (Glade and Fletcher, 1974).
Finally an aqua
60
FREQUENCY
RANGE
or 102)
0
5
10
15
20
25
0.01-0.25
0.26-0.50
0.51-0.75
0.76- 1.00
1.01- 1.25
1.26-1.50
1.51- 1.75
1
1.76-2.00
2.01-2.25
2.26-2.50
2.51-2.75
2.76-3.00
3.01-3.25
3.26-a5O
3.51-3.75
3.76-4.00
4.01-425
Figure 22-- Histogram showing the distribution of copper normalized to
iron (extracted using hot oxalic acid) in -30 mesh stream
sediment
RANGE
(PPM)
FREQUENCY
O
5
10
15
20
25
1- 10
11- 20
21- 30
31- 40
41- 50
51- 60
61- 70
71
-80
81 -90
91 -100
101 -110
Figure 23 -- Histogram showing the distribution of copper (extracted
sequentially using potassium perchlorate and hydrochloric acid
after oxalic acid) in -30 mesh stream sediment
61
regia /hydrofluoric acid leach was used to determine the residual
fraction for 20 samples (Filipek and Owen, 1978).
The analytical
methods are presented in Appendix II, while the results are presented in Appendix llla.
The results of each step are summarized
in the following discussion.
Oxalic Acid Leach.
To minimize the effects of large vari-
ations in the concentrations of iron, copper values were normalized
to iron.
Figure 22 and Plate 9 give the frequency and areal distri-
butions for this extraction.
In this extraction, a unimodal
frequency distribution was produced with an upper shoulder.
Assuming
the shoulder to contain the anomalous values, the threshold was set at
0.0100.
With this threshold, anomalous values occur in the areas
defined by the nitric acid extraction.
Although the area covered
by the northwestern anomaly does not change, the north -central
anomaly is significantly reduced in area as anomalous values do not
extend as far to the north.
This leach accounted for between 30 and 61% of the total
copper in the stream sediments (calculated using the sum of the
different fractions as the total; for samples in which the residual
fraction was not determined, a value of 15 ppm was assumed).
Within
the anomalous population, the percentage of copper extracted using
oxalic acid ranged from 40 to 61% of the total (x = 48.44 %, s = 4.51 %,
n = 21); on the other hand, in the non -anomalous population, the
percentage of total copper ranged from 30 to 57% (x = 43.20 %,
s = 6.40 %, n = 53).
At the 95% confidence level, these two
62
populations are statistically different, indicating that in the
anomalous samples, the oxide fraction constitutes a greater proportion of total copper than in the non -anomalous samples.
This is
probably due to the increasing relative importance of copper in the
residual fraction of the non -anomalous population.
While the copper
concentration in the oxide fraction decreases in the non -anomalous
samples, the residual concentration remains constant and has a
higher relative contribution.
In general, the oxalic acid extractable fraction contains
more copper than the potassium perchlorate -hydrochloric acid extractable fraction.
Only in sample AJ001S, which came from a wash
draining the area containing the New Cornelia tailings ponds, does
the reduced fraction predominate over the oxide fraction.
In all
but the lowest background samples, the oxide fraction predominates
over the residual fraction.
In summary, the oxide fraction is
quantitatively the most important fraction of this sequential
extraction.
Potassium Perchlorate -Hydrochloric Acid Leach.
This extract -
tion, originally designed for the analysis of base metal sulfides
(Olade and Fletcher, 1974), attacks the sulfide and organic portion of
the sample.
Both the frequency and areal distributions for the copper in
this step are slightly different from those of the oxalic acid and
nitric acid extractions.
Figure 23 and Plate 10 show the frequency
and areal distributions for this extraction.
The frequency distribution for this step has the appearance
of a log - normal distribution, as opposed to the bimodal distribution
63
observed in the nitric acid extraction.
tribution, the threshold is not obvious.
Due to the form of the disHowever, the values in
the northwestern anomalous area increase upwards from 40 ppm,
suggesting that this is the probable threshold.
With this threshold, the north -central anomaly does show up,
but with significantly less contrast than in the other methods.
Moreover, this anomalous area is more spread out, with no distinct
highs.
The northwestern anomaly does not change significantly in
either areal extent or character.
As with the other techniques,
the values decrease to southeast to values around 10 to 20 ppm.
Therefore this extraction shows the same areal distribution
as the other methods; however, the frequency distribution is significantly different, suggesting additional or different processes
controlled the dispersion of copper into the sulfide and organic
fraction of stream sediments.
Aqua Regia /Hydrofluoric Acid Leach.
This extraction is
designed to decompose silicate minerals, releasing copper and other
trace elements from silicate structures (Filipek and Owen, 1974).
Owing to the time required and the difficulty of the procedure,
only 20 samples were analyzed.
Samples were chosen to include both
anomalous and background samples as indicated by previous analyses.
The results indicate that this fraction has a relatively uniform,
low distribution throughout the study area.
Values ranged from 8 to
19 ppm with an average of 14.05 ppm (s = 3.03 ppm).
By inspection,
high values from this extraction show no correlation with high
64
values from other extractions.
Therefore, copper extracted using
this method probably represents the lithogeochemical background.
Summary.
The first sequential extraction indicated that the
copper that constitutes the anomalous values probably resides in
both the oxide, and organic and sulfide portions of the stream sediment.
The technique does not give any indication of exactly how the copper
is held in these two chemical fractions.
Copper held in the silicate
framework of the stream sediment does not contribute to the anomalous
values.
Results of the Second Sequential Extraction
To determine the mineralogic fractions that holds the copper,
a second, more selective sequential extraction (modified after Filipek
and Owen, 1978; modified after Chao and Zhou, 1983) involving five
separate steps was used.
The concentrations of manganese and iron
were also determined in each step.
The steps were intended to
remove the carbonate and exchangeable fraction, followed by the
easily reducible, moderately reducible, sulfide and organic, and
crystalline (silicate) fractions.
Although the steps attack princi-
pally the mineralogic fractions described, they are not perfectly
selective, so the values determined cannot be taken as a strict
description of the behavior of these elements according to the
mineralogic fraction.
To further define the phases that hold the copper, samples
were separated into three parts using bromoform: the portion that
sinks (the "heavies "), the portion that remains suspended (the
65
"slimes "), and the portion that floats (the "lights ").
The informal
terms "heavies ", "slimes ", and "lights" will be used in this paper
for clarity and efficiency.
The heavies contain minerals that have
a specific gravity of greater than 2.90 (the specific gravity of
bromoform) -- typically amphiboles, pyroxenes, olivine, sulfides and
other heavy minerals.
The slimes contain minerals that have spe-
cific gravities of about 2.90 and flocculant minerals such as clays.
The lights contain minerals that have specific gravities less than
2.90 such as feldspars, calcite and quartz.
All three fractions
were pulverized to -200 mesh and analyzed using the five -step extraction.
Additionally a bulk sample was also analyzed, making a total
of four separates per stream sediment sample.
Owing to the length of the procedure, only ten stream sediment samples were analyzed in this manner.
Four were selected from
the anomalous group of samples, three from a group considered
borderline anamalous, and three from samples representing the
background.
For comparison, a sample running 300 ppm copper held as
chrysocolla was prepared and analyzed.
selected.
Table 7 lists the samples
All four samples from the anomalous group came from the
northwest anomaly, while samples AJ012S and AJ015S of the borderline
Table 7 -- Samples analyzed using five -step sequential analysis
Anomalous Group:
AJ019S, AJ038S, AJ039S and AJ040S.
Borderline Group:
AJ012S, AJ015S and AJ049S.
Background Group:
AJ069S, AJ094S and AJ103S.
66
anomalous group came from the north -central anomaly.
The results of
this sequential extraction are given in Appendix IIIb, and they are
graphically displayed in Figure 24.
In general, the heavies have the highest concentrations of all
elements of interest in all mineralogic fractions, while the lights
have the lowest concentrations.
Because the lights comprise the
bulk of the samples (always greater than 87% by weight), the bulk
analyses reflect those of the lights.
The Distribution of Iron and Manganese.
More specifically,
both iron and manganese concentrate in the silicate fraction of the
heavies, slimes and lights.
iron in this fraction.
In fact, the heavies contain up to 29%
The other mineralogic fractions contain
less iron and manganese by several orders of magnitude.
Of the
other fractions, the moderately reducible, and the sulfide and organic
fractions contain most of the rest of the iron, whereas the manganese
content does not vary significantly.
In both the moderately reducible,
and the sulfide and organic fractions, the heavies and slimes contain
the most iron.
The concentrations of manganese and iron vary inde-
pendently of the concentration of copper, although the sulfide and
organic fraction of the anomalous samples does contain more iron
than that of the borderline and background samples.
The greatest variation between samples, density separates
and mineralogic fractions occurs in the concentration of copper.
The anomalous samples contain significantly more copper in all
mineralogic fractions for heavies, slimes and lights.
and slimes contain more copper than the lights.
The heavies
67
PPM
1000 --
700
0
BH S
CHYSOCOLLA
L
B
AJ019S
H
L
S
O
H
S
L
SYMBOL
500
8
H
S
L
AJ04OS
AJ03BS
AJ039S
ANOMALOUS SAMPLES
FRACTION
CRYSTALLINE
SULFIDE AND ORGANIC
300
®
MODERATELY REDUCIBLE
Iilil
EASILY REDUCIBLE
CARBONATE AND
EXCHANGEABLE
200
B
H
100
O
S
ñ
B
L
H
S
L
B
H
S
B
L
S
L
AJ049S
AJO15S
AJ012S
H
BULK
HEAVIES
SLIMES
LIGHTS
BORDERLINE SAMPLES
200
100
0
ii
:i%
.=°'
BH S
AJ069S
L
v,
..:_ j
B
H
S
T.!
L
AJ094S
BACKGROUND SAMPLES
B
7:77.
H
S
l
AJ103S
Figure 24 -- Distribution of copper among mineralogic and density
fractions of selected stream sediments, Batamote Mountains,
Arizona
68
The Distribution of Copper in the Crystalline Fraction.
Of
the five fractions analyzed, the least variation occurs in the crystalline fraction.
Although the heavies and slimes do contain more
copper in this fraction, the difference is small compared to the
variations seen in other fractions.
Additionally, the concentrations
of iron and manganese in this fraction do not vary significantly
relative to total copper content.
This indicates that the crystalline
fraction represents a background value; copper in other fractions
determine whether a sample is anomalous or not.
The Distribution of Copper in the Carbonate and Exchangeable
Fraction.
The carbonate and exchangeable fraction shows large
variation between anomalous and background, and between heavies,
slimes and lights.
Anomalous samples have a 10 to 20 times enrich-
ment over the background in this fraction.
Moreover, the heavies
show a two to four times enrichment over the lights and a lesser
enrichment over the slimes.
However, the percentage of total copper
accounted for by this fraction increases significantly from background
to anomalous samples; the percentage does not increase as markedly
for the slimes and heavies.
This implies that the lights are
affected the most by this mineralogic fraction.
The Distribution of Copper in the Easily Reducible Fraction.
On the other hand, although the anomalous samples have higher concentrations in the easily reducible fraction, the concentrations do not
vary significantly between heavies, slimes and lights.
The nature of
the extraction and the low variation between the density separates
suggest that this fraction occurs ubiquitously through the sample,
69
probably as coatings on grains.
The relatively low contribution of
this fraction to total copper and its ubiquitous nature indicate
that it is a quaternary affect of tertiary dispersion in the stream
sediment- -i.e., it is a product of higher order dispersion of the
copper introduced into stream sediment by secondary processes.
The Distribution of Copper in the Moderately Reducible, and
Sulfide and Organic Fractions.
The moderately reducible, and sulfide
and organic fractions show the greatest variability between heavies,
slimes and lights, and between anomalous and background.
Both
fractions have higher copper concentrations in the anomalous samples
and in the heavies and slimes.
The sulfide and organic fraction,
by far, has the largest contribution of copper in the heavies and
slimes, implying that it controls the distribution of copper within
these two density separates.
The distribution of the moderately
reducible fraction in the heavies and lights mimics this pattern.
However, in the lights the easily reducible and moderately reducible
fractions control the distribution of non -silicate copper.
In com-
parison, the sulfide and organic fraction contributes relatively
little copper to the lights.
This distribution is prevalent in the
anomalous and borderline samples; in background samples, the moderately reducible, and sulfide and organic fractions contribute little
copper in comparison to the crystalline fraction.
Summary. To summarize, the crystalline fraction represents
a regional background concentration of copper.
The anomalous values
stem from concentrations of copper in the carbonate and exchangeable,
easily reducible, moderately reducible, and sulfide and organic
69
probably as coatings on grains.
The relatively low contribution of
this fraction to total copper and its ubiquitous nature indicate
that it is a quaternary affect of tertiary dispersion in the stream
sediment- -i.e., it is a product of higher order dispersion of the
copper introduced into stream sediment by secondary processes.
The Distribution of Copper in the Moderately Reducible, and
Sulfide and Organic Fractions.
The moderately reducible, and sulfide
and organic fractions show the greatest variability between heavies,
slimes and lights, and between anomalous and background.
Both
fractions have higher copper concentrations in the anomalous samples
and in the heavies and slimes.
The sulfide and organic fraction,
by far, has the largest contribution of copper in the heavies and
slimes, implying that it controls the distribution of copper within
these two density separates.
The distribution of the moderately
reducible fraction in the heavies and lights mimics this pattern.
However, in the lights the easily reducible and moderately reducible
fractions control the distribution of non -silicate copper.
In com-
parison, the sulfide and organic fraction contributes relatively
little copper to the lights.
This distribution is prevalent in the
anomalous and borderline samples; in background samples, the moderately reducible, and sulfide and organic fractions contribute little
copper in comparison to the crystalline fraction.
Summary. To summarize, the crystalline fraction represents
a regional background concentration of copper.
The anomalous values
stem from concentrations of copper in the carbonate and exchangeable,
easily reducible, moderately reducible, and sulfide and organic
71
Follow -Up Phase
To check the distribution of copper in anomalous drainages,
samples were collected upstream of samples AJ003S and AJ039S.
Stream sediment samples with numbers greater than 140 are part of
The samples were analyzed using semi- quantitative
this group.
emission spectroscopy (with higher detection limits, however), the
nitric acid leach, the oxalic acid leach, and the potassium perchlorate- hydrochloric acid leach.
Ia and IIIa.
These results are given in Appendices
All analyses illustrate the same observation:
anomalous concentrations of copper do not change significantly up
drainage.
Figures 25 and 26 depict this point using the results of
the oxalic acid leach.
The lack of significant variation upstream from anomalous
samples implies that the input of anomalous copper occurs throughout the drainage area of anomalous sample sites.
This argues against
input from a single structure, or localized mineralization.
Instead,
the copper came from a source that does not change in intensity over
a wide area.
Summary of the Information Derived From Stream Sediments
Analysis of stream sediments yielded two anomalous areas
characterized by high concentrations of copper, bismuth and silver.
The presence of anomalous values on both sides of the Batamote
Mountains and the presence of significant copper in coarse sediment
indicate that airborne smelter contamination is unlikely.
72
Tba
'..
142(1.28)
/
143(1.47)
N
Tba
3$(2.27)
`
f
.
P>./.
/
\
/
K137(1.40
Qa
--
2000 FEET
SCALE: 1:24,000
Figure 25-- Distribution of copper normalized to iron (extracted using
oxalic acid) in -30 mesh stream sediment samples upstream of
sample AJ003S (concentrations in parentheses)
73
¡-
iL- )
4:,10(t71)
N
1.l
\\(2.56)
439
1
148(j.38)
1499
/
r
Iba
.(1.85)
;50(2.50)
Tba
11
(
154(2.39)
15301
,
i
.1
N
`"
QaN
Iba
\.
--
42(1.65)
2000 FEET
SCALE: 1:24,000
Figure 26-- Distribution of copper normalized to iron (extracted using
oxalic acid) in -30 mesh stream sediment samples upstream of
sample AJ039S (concentrations in parentheses)
74
Most of the anomalous copper is held in a reducible form
(probably iron or manganese oxides), although significant copper
does occur in a oxidizable form in the heavies and slimes (probably
organics, but possibly sulfides).
The source of the anomalous
copper occurs ubiquitously throughout the anomalous areas because
copper does not change concentration upstream.
Although the north-
western anomaly does have a spatial association with northerly
trending normal faults, the source of the copper cannot be traced
solely to these structures because of the ubiquitous nature of the
anomaly.
INTERPRETATIONS FROM HEAVY MINERAL CONCENTRATES
During the main phase of sample collection, heavy mineral
concentrates were collected at each sample site for a total of 78
Replicate samples were collected at four sites to confirm
samples.
anomalies shown in the main phase of sample collection.
After
preparation, the non -magnetic heavy mineral fraction was analyzed
using semi -quantitative emission spectroscopy, and its mineralogy
was examined visually.
Sulfide grains were extracted from the sam-
ples and analyzed for copper with a microprobe.
Finally, the C -1
and C -2 (magnetic) fractions were analyzed for copper using the
nitric acid extraction.
The methods used, results, and interpreta-
tions of this part of the study are discussed in this chapter.
Field Methods
As with stream sediments, samples were composited along a
100 foot reach of the drainage and passed through a 5 mm sieve in
the field.
Between 1500 and 3500 g (usually 2000 to 3000 g) of
sample were collected.
As no water was present in the field area,
samples were taken elsewhere and panned to remove the bulk of the
light minerals (e.g. feldspar and caliche).
For efficient panning,
fines were removed from the sample by kneading and washing.
Samples
were panned down so their dry weight was between 50 and 200 g.
The
samples were then taken to the laboratory for further preparation.
75
76
Sample Preparation
The panned samples were sieved through a 30 mesh screen;
the +30 mesh material was discarded.
Heavy minerals were then
separated using bromoform (s.g. = 2.90).
The lights were discarded.
The heavies were split into three magnetic fractions with a hand
magnet and a Frantz Isodynamic Magnetic Separator (front slope =
5 °; side slope = 10 °).
Table 8 gives the setting and typical
mineralogy of each fraction.
The minerals listed in the "C -3"
fraction include all the minerals observed during the study.
Table 8 -- Magnetic fractions and representative mineralogy
Fraction
Range (amps)
C-1
<0.2
C-2
0.2 - 0.6
<0.6
C -3
Mineralogy
Magnetite and ilmenite
Pyroxenes, amphiboles, olivine
and iron oxides
Sphene, zircon, apatite, pyrite,
chalcopyrite, covellite, arsenopyrite, galena, barite, cerussite, wulfenite ( ?), cassiterite, copper carbonates, lead shot,
caliche fragments, rock fragments and pyroxene
The presence of caliche fragments and pyroxenes in the C -3
(non- magnetic) fraction indicates that the process is not 100%
efficient.
The presence of lead shot points out one other signifi-
cant problem with this kind of a study: contamination due to cultural
activities.
Of the three fractions the C -1 and C -2 fractions had the
greatest mass.
Masses of the C -1 fraction ranged from 0.61 to 31.88
g, while those of the C -2 fraction ranged from 0.53 to 12.40 g.
77
The C -3 fraction has the least mass; it ranged from 0.04 to 1.29 g.
Both the C -2 and C -3 fractions were split.
One split from
each fraction was pulverized; the C -3 fraction was hand pulverized.
The C -1 fraction of ten samples was also pulverized.
Analysis of the C -1 and C -2 Fractions
The pulverized splits of the C -2 fraction, and the pulverized C -1 fraction of ten samples were analyzed using hot nitric
acid.
The results of the analysis are given in Appendix IIIc.
Figure 27 and Plate 11 depict the frequency and areal distributions,
respectively, for copper in the C -2 fraction.
As with the stream sediments, this sample medium shows a
bimodal distribution, implying possible background and anomalous
populations.
The modes occur at 15 ppm and 50 ppm.
However, the areal distribution is slightly different.
If
40 ppm or more is considered anomalous, the northwestern and north -central anomalies merge into one continuous anomaly with rather erratic
highs.
Moreover, anomalous values do not extend as far to the
east, and an anomaly in the south -central area appears.
As with
other sample media, the values fade off to the southeast.
Of possible greater significance, the values reported for
this analysis range from 30 to 260 ppm in the C -1 fraction and 15
to 100 ppm in the C -2 fraction.
As shown in the previous chapter,
the concentrations of copper using the same nitric acid extraction
in the heavies and the slimes separated directly out of stream
sediments (i.e. without washing away the fines) ran upwards to
78
FREQUENCY
VALUE
0
(PPM)
1-
10
15
20
25
10
11-
20
21-
30
3141516171-
40
50
60
70
80
81- 90
91 -100
Figure 27 -- Histogram showing the distribution of copper (extracted using
hot nitric acid) in the C -2 fraction of heavy mineral concentrates
79
1000 ppm copper.
Obviously, the values observed in the C -1 and C -2
fractions cannot explain the high values of the stream sediment
heavies.
Therefore, the copper must occur in some other form--
in either the C -3 fraction or in the fines washed away during the
panning process.
reasons.
The lost fines are the better candidate for two
First, due to its relatively small mass contribution, the
C -3 fraction cannot produce the required copper (in fact, analyses
of this fraction indicate maximum concentrations of copper to be
300 ppm).
Second, the slimes --which would have been washed away
during panning --also have high concentrations of copper.
Therefore
the lost fines probably contain high concentrations of copper to
account for the copper in the heavy fraction of stream sediments.
Spectroscopic Analysis of the C -3 Fraction
The C -3 fractions of all 78 initial samples and four replicate samples were analyzed for 31 elements using semi- quantitative
emission spectroscopy.
Because different weights of sample were
used in the analysis, the detection limits are different.
The
results of this analysis and the detection limits are presented in
Appendix Ic.
The four replicate samples were collected in order to confirm
anomalies found in the original 78 samples.
are listed in Table 9.
Replicate sample pairs
In all cases, the anomalies were confirmed;
however, the replicate values did fluctuate significantly from the
original values.
One of the most severe problems with the type of
sample is the high variation of values in samples collected at the
80
Table 9-- Replicate heavy mineral concentrate sample pairs
AJ011C - AJ132C
AJ090C - AJ127C
AJ013C - AJ128C
AJ105C - AJ117C
same site.
This is due both to the small size of the analytical
sample (5 mg) and to the small amount of sample actually realized
when preparation is finished.
These problems should be considered
when reading this or other studies using the non -magnetic fraction
of heavy mineral concentrates as a sample medium.
The distribution
of copper and other economic and economically -related elements are
discussed in the following section.
Copper
Both the frequency and areal distributions of copper in the
C -3 fraction of heavy mineral concentrates (see Figure 28 and Plate
12, respectively) differ from those in the whole stream sediment.
The correlation coefficient between these two sample media is only
0.4395 for copper.
The frequency distribution for this medium is
unimodal, with the mode occurring at 70 ppm.
Assuming the top 10%
of the values to be anomalous, the threshold is 200 ppm.
With this threshold, the anomalous values of copper occur
without any systematic order.
However, if a cutoff of 150 ppm
were used (this includes 63% of the samples), the northwestern two -
thirds of the study area would be anomalous.
This area would be
consistent with --but much larger than --the anomalous areas observed
with stream sediments.
This sample medium does not enhance the values observed in
stream sediments.
The high values reported in both media are about
81
VALUE
(PPM)
FREQUENCY
O
5
10
15
35
40
N(2)
L (2)
2
3
5
7
10
15
20
30
50
70
100
150
200
300
J
Figure 28 -- Histogram showing the distribution of copper in the nonmagnetic fraction (C -3) of heavy mineral concentrates
82
300 ppm.
Therefore, the minerals in the C -3 fraction cannot be the
major cause of the anomalies observed in stream sediments.
The
distribution observed is consistent with known anomalies, but it
does not enhance them in any way.
Other Elements
A totally unexpected result of this study is the discovery
of significant anomalous values for other interesting elements besides
copper in the non - magnetic fraction of heavy mineral concentrates.
Plate 13 shows the distribution of anomalous values (upper 10 to
15% of reported values) of silver, arsenic, barium, copper, molybdenum, lead, antimony, tin and zinc.
Figures 29 through 36 show the
frequency distributions of these elements (except copper).
The distribution of anomalous values is rather widespread
within the study area.
To pick out possibly significant anomalies,
the clustering of anomalous values of elements with similar geochemical associations was used as the primary criterion.
Based on this,
three anomalies were considered most significant.
The first anomaly, located in the northwest portion of the
study area, consists of a tight grouping of three samples with
anomalous values of molybdenum and tin.
this one has the easiest explanation.
Of the three anomalies,
The samples come from washes
that drain the Childs Latite in the area that alteration was observed.
The Childs Latite has also produced anomalous tin in other
parts of the Ajo 1° by 2° quadrangle (P.K. Theobald, personal communication, 1983).
83
VALUE
(PPM)
FREQUENCY
0
5
70
10
t l
N(O.2)
L(O.2)
0.2
0.3
0. 5
0.7
1
1.5
2
3
3
5
7
10
15
20
30
J
Figure 29 -- Histogram showing the distribution of silver in the nonmagnetic fraction (C -3) of heavy mineral concentrates
VALUE
(PPM)
0
FREQUENCY
5
10
70
75
N(1OO)
L(1OO)
100
150
200
300
500
700
Figure 30-- Histogram showing the distribution of arsenic in the nonmagnetic fraction (C -3) of heavy mineral concentrates
84
VALUE
(PPM)
FREQUENCY
0
5
10
15
N(50)
L(50)
50
70
100
150
200
300
500
700
1000
1500
2000
3000
5000
7000
10,000
.J
j
Figure 31 -- Histogram showing the distribution of barium in the nonmagnetic fraction (C -3) of heavy mineral concentrates
VALUE
(PPM)
FREQUENCY
0
5
10
65
70
N(10)
L(10)
10
J
15
20
30
50
70
100
3
150
200
3
Figure 32 -- Histogram showing the distribution of molybdenum in the
nonmagnetic fraction (C -3) of heavy mineral concentrates
85
VALUE
(PPM)
FREQUENCY
0
5
10
15
20
25
30
N(5)
L ( 5)
5
7
10
15
20
30
50
70
100
150
200
300
I
I
500
700
1000
1500
3
2000
Figure 33 -- Histogram showing the distribution of lead in the non magiñetic fraction (C -3) of heavy mineral concentrates
VALUE
(PPM)
FREQUENCY
0
N(20)
L(20)
20
30
50
70
100
J
5
70
10
l
75
=1
3
Figure 34 -- Histogram showing the distribution of antimony in the nonmagnetic fraction (C -3) of heavy mineral concentrates
86
VALUE
(PPM)
N(10)
LOO)
FREQUENCY
0
5
10
15
20
25
30
35
J
10
15
20
30
50
70
100
150
200
300
500
700
1000
J
J
J
Figure 35 -- Histogram showing the distribution of tin in the nonmagnetic fraction (C -3) of heavy mineral concentrates
VALUE
(PPM)
FREQUENCY
0
5
10
75
80
N(100)
L(100)
100
150
200
300
500
J
Figure 36 -- Histogram showing the distribution of zinc in the non magnetic fraction (C -3) of heavy mineral concentrates
87
The second anomaly, defined by a clustering of four sample
sites showing high values of the volatile elements arsenic and antimony with lesser copper, molybdenum and tin, occurs in the north central part of the study area.
Of the four sites, two were re-
sampled, confirming the anomaly.
A contiguous sample also contained
grains of chalcopyrite and covellite (see next section) although only
70 ppm was reported in the analysis.
No geologic expression of the
cause of the anomaly was observed by traversing the drainage.
But
owing to colluvium on the walls of the canyons, any alteration present could easily be missed.
The anomaly deserves follow -up work
in the future.
The final anomaly, located towards the southeast, consists
of a group of six samples showing high values of silver, molybdenum
and arsenic.
This anomaly is the most obscure because its cause
was not seen on the ground or during visual examination of the
samples (with the exception of one sample which contained arsenopyrite).
Apart from the three anomalies just described, other samples
could be considered anomalous.
However, they are not discussed
because they do not meet the previously described criteria.
Mineralogy of the C -3 Fraction
To determine the sources of metals in the non -magnetic fraction, the non -pulverized split of each sample was examined under
the binocular microscope to determine the minerals present.
Ore
88
and related minerals are commonly preserved in stream sediments under
conditions of rapid erosion.
This fraction contains sphene, zircon and apatite as the
dominant minerals.
Pyrite, chalcopyrite, covellite, arsenopyrite,
galena, barite, cerussite, wulfenite ( ?), cassiterite and malachite
occurred in one or more samples.
Other significant materials ob-
served in the samples include lead shot, caliche fragments, rock
fragments and pyroxene.
Plates 14 and 15 show the distribution of
economically significant and related minerals.
From these data, two generalizations can be made.
pyrite occurs throughout the study area.
First,
Its widespread occurrence
implies pyrite is probably a minor accessory mineral in the Batamote
Andesite.
Second, high values of lead, bismuth, antimony and tin should
not be trusted.
In three samples, lead shot was observed, raising
the possibility of contamination in other samples.
mony and tin are common alloys in shot.
Bismuth, anti-
Solitary high lead values
should be regarded with suspicion.
Other minerals reflect the analytical values to greater and
lesser degrees.
Arsenic occurs as arsenopyrite; lead occurs as
galena, lead shot, cerussite or wulfenite; copper occurs as chalcopyrite, malachite and covellite; and tin occurs as cassiterite.
The second anomaly, as described above, is caused by the
presence of arsenopyrite, chalcopyrite, malachite and covellite.
the third anomaly, only one sample contained arsenopyrite.
In
Other
scattered mineral occurrences were observed through the study area.
89
The Concentration of Copper in Pyrite Grains
Pyrite grains represent a possible source of copper within
the heavies and therefore the stream sediments.
To test this hypoth-
esis, pyrite grains were extracted from seven samples and analyzed
for copper using a microprobe.
besides pyrite were found.
During this analysis, other minerals
Although the majority of the grains did
turn out to be pyrite, grains of rutile, chalcopyrite, arsenopyrite
and covellite were also analyzed.
given in Table 10.
The results of this analysis are
The galena grain was analyzed to determine its
identity.
Of the samples analyzed, two are considered anomalous (based
on copper values in stream sediments), two samples are considered
borderline anomalous and three samples are at background. Although
some pyrite grains in the anomalous samples did contain significant
copper (up to 3400 ppm), the average grain from the anomalous
samples did not contain significantly more copper than grains from
the background samples.
Therefore, the copper held in pyrite cannot
explain the anomalous copper present in stream sediments.
Summary
The distribution of copper in the C -3 fraction of heavy
mineral concentrates reflects that in the stream sediments in a very
general way.
The northwestern anomaly shows up when the threshold
is 150 ppm; however, at this threshold 63% of the samples would be
considered anomalous.
More importantly, the anomaly is not enhanced
90
Table 10-- Concentrations of copper in pyrite grains from selected heavy
mineral concentrate samples
Sample
Grain
Cu
AJ029C
0.091
0.040
0.029
47.833
47.358
47.921
48.136
47.934
47,753
48.093
47.917
47.433
47.591
47.715
53.973
53.912
53.967
54.030
53.854
54.256
54.214
54.181
53.962
54.197
54.012
0.000
0.002
0.141
0.341
0.072
0.002
47.499
47.568
46.634
46.588
46.322
47.619
51.940
30.689
64.709
0.00.0
30.774
0.038
47.814
0.003
0.035
0.023
0.007
46.558
47.327
47.191
48.057
53.003
53.188
0.006
0.000
0.013
0.000
0.006
47.980
35.592
35.744
35.240
35.367
54.020
0.011
0.001
0.000
0.026
46.751
47.412
47.077
47.210
53.557
53.562
54.078
53.879
-11.177
0.000
0.000
-46.289
47.892
0.000
0.010
0.023
0.071
0.000
0.014
0.113
1
2
3
4
5
6
7
0.049.
8
9
AJ037C
1
2
3
4
AJ056C
--
1
2
3
4
AJ069C
1
2
3
4
AJ076C
1
2
3
4
5
AJ077C
1
2
3
4
AJ091C
'
1
2
3
Concentration (percent)
Pb
As
S
Fe
---
Total
101.806
101.279
-
101.911
102.236
101.789
102.024
102.240
102.146
101.486
101.827
101.757
--
10-0.166
-r-
---
--
--
99.389
52.596.
--
51.643
53.688
52.654
53.949
98.419
100.617
99.058
101.571
96.300
92.401
101.465
53.65.1
99.563
100.549
.
53.7.11
--
100.9.26
53.927
--
101.991
23.001
20.775
22.533
54.018
53.832
PY
PY
py
PY
PY
PY
PY
PY
PY
1Y
PY
PY
py
ru
34.837
27.654
22.82.1
Mineral
-40.938
40.971
40.934
--
40.909.
83.870
--
cv
py
py
py
py
py
102.005
99.351
99.778
96.949
98.815
py
100.319
100.975
py
py
py
py
10.1.155
10.1.166
--
cp
95.047
100.307
10.1.724
as
as
as
as
gn
py
py
91
relative to stream sediments in this fraction, implying that this
fraction is not the primary source of copper in the anomalous areas.
The low values of copper in the C -1 and C -2 fractions preclude
them from being a significant source of anomalous copper.
This
suggests that the bulk of the copper present in the heavy fraction
of stream sediments could occur in fines that were washed away during
the panning process.
The high copper values in the slime fraction
of the stream sediments supports this assertion.
Copper is not held to a significant degree in pyrite, which
implies the copper held in a reduced form probably occurs as organics.
Since the slimes would be expected to contain organics in preference
to sulfide, the high concentrations of oxidizable copper (along with
relatively low concentrations of reduced iron) in the slimes support
this hypothesis.
The most intriguing results of this part of the study are the
presence of high concentrations of volatile and base metals in
certain parts of the study area.
Of the three anomalies defined by
heavy mineral concentrates, only one has a ready explanation.
OTHER RESULTS
As a test of the hypothesis that the anomaly could be caused
by dispersion from material within or related to the normal faults,
samples containing oxide coatings along fractures or broken zones
within the Batamote Andesite were collected in both anomalous and
background areas.
Three samples (AJ136R, AJ152R and AJ155R)
were collected in areas considered to be anomalous, and six samples
(AJ162R through AJ167R) were collected in areas considered to be
background (see Plate 2 for locations).
The oxide coatings were
removed using a hot oxalic acid leach and analyzed using semi -
The results are tabulated in
quantitative emission spectroscopy.
Appendix Id.
Because the anomaly of interest is comprised of high values
of copper, silver and bismuth, this discussion will concentrate on
these three elements.
Of these, copper and bismuth showed a signifi-
cant enrichment in the samples collected the anomalous area.
Copper
is enriched by factors ranging between 6 and 20, and bismuth is enriched by factors between 20 and 50.
This indicates that these
coatings are possible sources of bismuth and copper in anomalous
stream sediments.
However, silver is concentrated in the samples from non -
anomalous areas by factors up to 15.
But the highest concentrations
of silver also come from a drainage area that has high silver in
92
93
heavy mineral concentrates --part of the third anomaly discussed in
the previous chapter.
Other elements that show some enrichment in the samples from
anamalous areas include arsenic, beryllium, antimony and tin.
Therefore the enrichment of these elements -- espically copper
and bismuth --lends credence to the hypothesis that the anomalous
copper values were derived from dispersion from normal faults and
fractures within the northwestern part of the study area.
On sample AJ136R, oxides as "limonite" extend into the rock
for up to one cm.
The silicate minerals within this zone were not
altered to a greater extent than in the rest of the rock.
calcite was observed in the zone in addition to the oxides.
However,
The
lack of alteration of silicates in this zone indicates that the
,waters that deposited the copper and bismuth in this crack were
relatively cool.
SUMMARY OF DATA PRESENTED,
EVALUATION OF WORKING HYPOTHESES, AND CONCLUSIONS
The distribution of trace elements (principally copper,
silver and bismuth) in stream sediments and rocks of the Batamote
Mountains was examined in this study to determine the cause of
anomalous values of copper reported in earlier studies.
The Batamote Andesite has a copper concentration of around
30 ppm, which is relatively low for rocks of similar compositions.
The values of copper have a very tight distribution, implying that
copper has a homogeneous distribution throughout the unit.
The
Batamote Andesite is the predominant bedrock in the study area,
so its copper concentration must control background copper concentrations in stream sediments from washes draining the mountains.
Analysis of stream sediments defined two anomalous areas
within the Batamote Mountains, which are characterized by the suite of
copper, bismuth and silver.
The most significant anomaly, located in
the northwestern part of the study area, has a distinct spatial association with a series of northerly trending normal faults.
The
second anomaly, located in the north -central part of the study area,
has no obvious lithologic or structural control.
In several of the
chemical extractions, a definite trough separated the two anomalous
areas; however, in other extractions and sample media, the two
anomalous areas merged together, suggesting that they might be
part of one larger anomaly.
Since copper values do not vary
94
95
significantly upstream of anomalous sample sites, the input of
anomalous material comes from throughout the drainage basin; therefore, anomalies cannot be traced to a localized source.
Detailed sequential extractions imply that the copper in
anomalous samples is held dominantly in a reducible state although significant copper is held in an organic or sulfide state in the heavies
and slimes of stream sediments.
Values of copper in all fractions of
heavy mineral concentrates cannot account for the values observed
in the heavies and slimes of stream sediments.
Since fines are lost
during the panning process, this material could contain the missing
copper.
In fact, the high values for slimes support this hypothesis,
as they would tend to be washed away during panning.
Analysis of pyrite grains extracted from the non -magnetic
fraction of heavy mineral concentrates demonstrates that coarser
grained sulfide cannot account for the copper anomalies observed
in any sample medium.
Analysis for other elements in the non - magnetic fraction
of heavy mineral concentrates produced three other anomalies not
related to the stream sediment anomalies.
One anomaly, character-
ized by tin (cassiterite) and molybdenum, occurs in an area where
extensive alteration was observed in the Childs Latite.
The other
two anomalies, characterized by arsenic and antimony, and silver,
molybdenum and arsenic, respectively, remained unexplained.
No
alteration, other than the presence of chalcedony and zeolites, was
observed in these two areas.
Finally, analysis of oxide coatings from fractures in both
96
anomalous and non -anomalous areas (as determined from stream sediments) show that oxide coatings in anomalous areas contain signif icantly more bismuth and copper than those in non -anomalous areas.
Evaluation of Working Hypotheses
In the introduction to this paper, five working hypotheses
were presented as possible explanations for the anomalies observed
by Barton and others (1982).
In this section, each hypothesis is
reviewed in the light of the data generated by this study in order
to determine its relative merit.
Airborne Contamination from a Smelter in Ajo
This hypothesis calls upon wind blown smelter dust from Ajo
as the source of copper.
This mechanism is unlikely because the
anomaly does not decay significantly downwind from the smelter
(anomalous values occur on both sides of the Batamote Mountains),
and the coarser fractions contain anomalous values of copper
(smelter dust is very fine grained).
Therefore, this mechanism
probably did not cause the observed anomalies, although it cannot
be ruled out due to the immense amount of copper that went up the
stack of the Ajo smelter.
Abnormally High Background in the Batamote Andesíte
Another possible source of copper is the rock unit that the
washes drain.
However, analysis of samples of the Batamote Andesíte
give a background value of around 30 ppm for copper.
Since anomalous
values in stream sediments range upwards to 280 ppm, this mechanism
is impossible.
97
Primary Mineralization
Primary hydrothermal mineralization alone could not account for
the broad copper anomalies observed in the stream sediments.
Yet, it
best explains the three anomalies observed in heavy mineral concentrates.
The minerals that cause the anomalies include primary minerals.
But in two of the anomalies, evidence for primary mineralization
was not observed on the ground.
Dispersion Along Normal Faults
Most evidence presented in this paper suggests that the best
explanation for the anomalies observed in stream sediments is that
they were produced as the result of dispersion of metals from oxide
coatings in faults and joints in the northwestern part of the study area.
Two principal pieces of evidence point to this mechanism.
First, the
anomalous values have a definite spatial association with the normal
faults.
Second, analysis of oxide coatings from fractures in the anoma-
lous areas indicate that they have concentrated both copper and bismuth
relative to oxide coatings in fractures from non -anomalous areas.
On the other hand, the fact that entire drainages contribute
significantly to the anomalies implies that the actual faults were
not the only contributors to the anoalies.
Mineralized fractures
and joints within the northwestern faulted block also probably
contributed significant metals.
The evidence presented to this point ties the source of
metals in stream sediments to oxide coatings in faults, joints and
fractures in the northwestern section of the study area.
However,
98
a more basic and interesting problem remains to be solved:
original source of metals in these structures.
the
Clearly, the metal
in the faults, joints and fractures is the result of secondary or
even tertiary disperson from some other source.
Possible sources of the metals in the faults, joints and
fractures include:
1. Unusual weathering processes that somehow
concentrated metals from background andesite into weathering rinds
along openings in the rock; 2. A higher water table that allowed
groundwater to deposit the metals; 3. Solutions migrating from the
New Cornelia Deposit; and 4. An upper -level hydrothermal system in
the Batamote Andesite that deposited metals that were subsequently
concentrated into the oxide coatings.
This should not be consid-
ered an exhaustive list, as many other mechanisms could be called
upon to deposit the metals; however it does include the most reasonable
(in the author's view) possibilities for a source of metal.
Weathering can and does produce oxide coatings that significantly concentrate metals relative to their host rock.
However,
oxide coatings from, the anomalous area contain significantly more
copper and bismuth than those from the background.
Presumably,
weathering of the Batamote Andesite could not account for the great
differences in metal concentrations observed, and it could not
produce the observed distributions.
If a higher water table existed in the recent geologic past,
solutions enriched in metals leached from rock below could provide
the metals observed in the oxides.
The original source of the metals
would have had to be relatively close, possibly directly below, the
99
observed anomaly.
This would be a reasonable mechanism to produce
the metals in the faults, joints and fractures.
The third possibility, lateral migration of supergene
solutions from the New Cornelia orebody, is unlikely because of the
long distances involved (up to 10 miles), and because the observed
metal assemblage in the stream sediments (Cu- Bi -Ag) differs from
that observed around the orebody (Cu- Mo -Pb) (P.K. Theobald, personal
communication, 1984).
Therefore, this mechanism is considered
unlikely.
The fourth alternative in which the primary metals were
deposited by the distal portion of a hydrothermal system and then
weathered and deposited into oxide coatings in faults and joints, is
considered the best possibility for several reasons.
First, although no
extensive hydrothermal alteration is present in the Batamote Andesite,
evidence for hydrothermal circulation does exist.
Chalcedony fills
joints and fractures throughout the unit, and a "limonite" multi -
spectral imaging anomaly exists around the intrusive plug.
It is
not unreasonable that a hydrothermal cell developed during or shortly
after the volcanism that produced the Batamote Andesite.
Second, the anomalies observed in the heavy mineral concentrates are best explained as the results of hydrothermal activity.
The arsenic- antimony anomaly observed in the north -central
section of the study area would be best explained as the result
of primary low temperature hydrothermal circulation.
The scattered
base metal anomalies could also be produced by hydrothermal activity.
Therefore, a distal hydrothermal system could provide the
100
necessary metal as sulfide, which in turn could be weathered and
redeposited into faults, fractures and joints as oxides.
It should be remembered that the above discussion is only
speculation about the source of the metals in the faults --none of
the
hypotheses presented could be confirmed by this type of a
study.
They should be regarded as working hypotheses for future
investigations.
Based on the data presented, the only conclusion
that can be made is that the observed anomalies are best explained
as dispersion into stream sediments from metals tied up with
faults, fractures and joints in the northwestern section of the
study area.
Contamination of the Batamote Andesite During its Eruption
The mechanism involving contamination of the Batamote Andesite before or during its eruption is also unlikely.
The back-
ground values for the Batamote Andesíte are too low to allow total
assimilation of the contaminant to be a cause.
Additionally, the
copper values show no zonation relative to the central vent from
which the unit was extruded as might be expected from contamination
without assimilation.
Therefore this mechanism is considered
unlikely.
Conclusions
At least two processes were involved in the production of the
observed anomalies: primary mineralization and dispersion along
normal faults.
The anomalies observed in the non -magnetic fraction
of heavy mineral concentrates are best explained as a result of
101
primary mineralization.
The minerals observed in this fraction
include primary sulfides of copper, lead and arsenic.
These minerals
usually occur in hydrothermal environments.
The copper- bismuth -silver anomalies observed in stream
sediments are best explained as the result of higher order dispersion
from metal held as oxide coatings along fractures and joints.
The original source of the metals that were deposited in the oxide coatings still remains unresolved.
Viable possibilities include ground-
water solution and deposition and distal hydrothermal activity in
the Batamote Andesíte.
Assuredly, these are not the only possibil-
ities, but they can serve as models for further exploration in the
area.
Given the location of the study area within the porphyry
copper belt of southwestern North America and the requisite size of
the original copper source to produce such a widespread anomaly, the
potential for a porphyry copper deposit buried in the subsurface
below the Batamote Andesite as the original source of metals exists.
This potential is enhanced by the presence of a magnetic dipole coincident with the copper- bismuth -silver anomaly presented in this paper
(Klein, )982).
Additionally, the anomaly lies along the Jemez lineament,
upon which the New Cornelia and Casa Grande West porphyry copper deposits lie.
Therefore a potential for porphyry copper mineralization
exists below the Batamote Mountains.
APPENDIX Ia
ANALYTICAL RESULTS (USING SEMI -QUANTITATIVE EMISSION SPECTROSCOPY)
FOR ROCK CHIP SAMPLES, BATAMOTE MOUNTAINS, ARIZONA
102
103
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10
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AJ046R
AJ047R
AJ048R
AJO5OR
AJ054R
AJ062R
AJ071A
AJ071B
AJ073R
AJ086R
50
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AJ111R
AJ112R
AJ113R
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AJ115R
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10
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20
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20
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30
20
20
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10
20
15
15
20
30
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L
V
N
15
15
N
20
N
100
100
100
N
N
N
L
N
L
L
L
N
200
150
N
N
N
N
N
30
30
30
30
30
N
N
N
N
N
N
500
N
500
500
N
N
N
N
N
N
N
N
N
N
5
20
N
100
50
50
100
100
70
50
50
N
N
N
N
N
200
200
100
200
100
1000
L
N
50
20
20
50
30
N
N
N
N
N
500
300
2000
500
L
5
20
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
10
20
N
20
N
300
150
200
50
200
200
L
L
N
L
50
20
30
20
50
N
N
N
N
N
100
50
100
500
500
500
N
500
N
20
50
50
50
20
L
L
N
N
N
N
N
500
30
N
N
N
N
N
200
200
200
100
200
20
20
20
20
10
N
N
N
N
N
L
L
N
N
N
N
N
100
70
100
100
70
500
500
500
500
500
N
N
N
N
N
N
N
N
15
15
N
N
N
N
N
70
300
200
200
30
L
L
L
L
N
N
N
N
10
N
N
N
50
50
50
N
100
100
70
70
L
500
500
500
500
200
N
10
Th
(PPm)
Zr
(PPm)
Zn
(PPm)
20
N
N
N
N
Y
(PPm)
W
(PPm)
N
(PPm)
N
(PPm)
(PPm)
(PPm)
(PPm)
50
50
20
Sr
(PPm)
Sn
(PPm)
Sc
Sb
Pb
Ni
AJOO4R
AJOO6R
AJOO9R
AJ025R
AJ026R
Sample
Appendix Ta -- continued
ó
ui
AJ138R
AJ139R
AJ14OR
AJ144R
AJ146R
Basaltic
Vesicular
Vesicular
Basaltic
Vesicular
andesite
andesite
andesite
andesite
andesite
Basaltic andesite
Caliche
Basaltic andesite
Caliche
Caliche
AJ135R
AJ137A
AJ137B
AJ137C
AJ137D
andesite
andesite
andesite
andesite
andesite
Hydrothermally breccíated andesite
Chalcedony
Basaltic andesite
Vesicular andesite
Basaltic andesite
Intrusive
Vesicular
Basaltic
Basaltic
Vesicular
AJ122R
AJ123R
AJ124R
AJ125R
AJ126R
Latite
andesite
andesite
andesite
andesite
AJ129R
AJ13OR
AJ131R
AJ133R
AJ134R
Basaltic
Intrusive
Basaltic
Intrusive
Description
AJ116R
AJ118R
AJ119R
AJ12OR
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Sample
Appendix Ia-- continued
Fe
1.5
1.5
2
5
2
2
1
1
1
5
3
3
2
1
1
1.5
5
5
3
1.5
1.5
2
1.5
1
1.5
7
1
1
1
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20
1.5
20
20
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0.3
0.3
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1
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1,5
5
5
1
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0.5
1
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1.5
1.5
1.5
1.5
0.1
1
0.02
2
2
1.5
1.5
2
2
5
2
1.5
1.5
1.5
1.5
Ca
3
3
3
1
1
3
2
Mg
0.2
(%)
0.3
0.5
0.5
0.5
0.3
0.05
0.5
0.05
0.05
0.5
0.3
0.03
0.3
0.5
0.5
0.2
0.3
0.5
0.5
0.5
0.3
0.3
0.3
0.5
0.5
Ti
2000
1000
1000
1000
1000
1000
200
1000
100
100
1000
300
1000
1000
1000
1000
1000
1000
1000
1000
700
1000
1000
1000
1500
5
N
N
N
1
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Ag
iPPm)
Mn
(PPm)
As
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
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107
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AJ139R
AJ14OR
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AJ137A
AJ137B
AJ137C
AJ137D
AJ129R
AJ13OR
AJ131R
AJ133R
AJ134R
15
20
20
20
15
20
L
L
5
20
10
15
15
N
10
15
15
N
N
N
N
N
N
N
N
N
N
N
20
20
20
20
L
20
20
20
N
N
10
N
N
N
N
N
N
N
10
20
20
20
20
15
15
10
20
10
N
N
15
N
15
15
15
N
7
15
10
10
20
20
10
15
10
L
10
10
20
20
30
30
L
L
20
50
30
30
20
N
N
N
N
N
N
70
L
70
N
L
50
100
100
100
70
500
500
500
500
200
500
500
500
500
500
N
N
N
N
N
N
N
N
N
N
N
N
N
20
N
30
30
30
N
N
N
N
N
50
20
70
100
100
500
100
500
500
500
N
N
N
N
N
N
20
20
30
30
30
N
N
N
N
N
100
100
70
70
70
500
500
500
500
500
N
N
N
N
N
70
70
20
N
N
AJ122R
AJ123R
AJ124R
AJ125R
AJ126R
10
20
70
70
70
100
10
15
15
20
N
N
10
20
30
50
20
N
N
N
N
N
50
500
500
500
500
500
N
N
N
N
N
5
N
10
10
10
20
20
20
20
100
AJ116R
AJ118R
AJ119R
AJ12OR
AJ121R
Y
(PPm)
W
(PPm)
(PPm)
(PPm)
(PPm)
(PPm)
(PPm)
(PPm)
V
(PPm)
Sr
Sn
Sc
Sb
Pb
Sample
Ni
Appendix Ia -- continued
200
200
150
200
200
L
N
L
L
N
N
N
N
N
N
20
300
20
20
200
300
200
200
200
200
N
N
L
N
L
L
L
N
N
300
L
N
N
N
N
N
N
N
N
N
N
N
N
200
200
200
200
200
10
50
70
200
L
L
L
200
L
150
150
150
200
50
L
200
200
N
N
N
N
N
Th
(PPm)
Zr
(PPm)
Zn
(PPm)
o
oo
f,-
Basaltic andesite
Caliche
Vesicular andesite
AJ160A
AJ160B
AJ161R
andesite
andesite
andesite
andesite
andesite
Vesicular
Vesicular
Basaltic
Vesicular
Basaltic
Description
AJ147R
AJ151R
AJ156R
AJ157R
AJ159R
Sample
Appendix Ia-- continued
Fe
2
1.5
5
1
3
1.5
1.5
1.5
1.5
20
1
3
1
1
5
2
1.5
0.7
1
5
Ca
(%)
5
1
3
Mg
0.5
(%)
Ti
0.5
0.05
0.3
0.3
0.5
0.5
0.5
0.3
CZ)
Mn
1000
200
2000
1000
1000
1000
1000
1000
íPPm)
Ag
N
N
1.5
1
L
N
N
N
(PPm)
N
N
N
N
N
N
N
N
As
(PPm)
N
N
N
N
N
N
N
N
AJ160A
AJ160B
AJ161R
(PPm)
Au
AJ147R
AJ151R
AJ156R
AJ157R
AJ159R
Sample
20
10
20
10
20
20
10
20
(PPm)
B
Appendix Ia -- continued
300
700
700
700
700
700
700
700
Ba
(PPm)
1.5
N
1.5
1.5
1.5
1.5
1.5
1
(PPm)
Be
Bi
N
N
N
N
N
N
N
(PPm)
Cd
N
N
N
N
N
N
N
N
(PPm)
Co
30
N
30
20
20
20
20
15
iPPm)
Cr
10
70
50
20
50
70
30
30
(PPm)
30
15
30
20
30
15
20
30
100
20
50
70
100
100
100
70
La
iPPm)
Cu
Wm)
N
N
N
N
N
N
N
N
(PPm)
Mo
L
N
L
L
L
L
L
L
(PPm)
Nb
50
5
50
20
10
20
10
20
20
20
20
15
20
20
20
20
Pb
(PPm)
Ni
(PPm)
Sb
N
N
N
N
N
N
N
N
(PPm)
20
N
15
15
15
15
15
10
(PPm)
Sc
N
N
N
N
N
N
N
N
(PPm)
Sn
0.1
200
10
10
20
Ag
As
Au
B
Ba
Mn
Ca
Ti
0.05
0.02
0.05
0.002
10
ppm
ppm
ppm
ppm
ppm
%
%
%
%
ppm
Lower
Detection
Limit
Fe
Mg
Element
Ni
Mo
Nb
Cu
La
Bi
Cd
Co
Cr
Be
Element
Lower detection limits:
5
20
5
20
5
1
10
20
5
10
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
Lower
Detection
Limit
Zr
Zn
Y
W
V
Sn
Sr
Sc
Pb
Sb
Sr
100
L
100
70
100
100
70
70
(PPm)
V
10
50
10
200
10
10
100
5
10
100
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
Lower
Detection
Limit
500
300
500
500
500
500
500
500
(PPm)
Element
L = Detected at levels below the detection limit
N = Not detected at lower detection limit
AJ160A
AJ160B
AJ161R
AJ147R
AJ151R
AJ156R
AJ157R
AJ159R
Sample
Appendix Ia -- continued
W
Th
Element
N
N
N
N
N
N
N
N
(PPm)
Y
Zn
100 ppm
N
L
N
L
L
L
L
L
(PPm)
Lower
Detection
Limit
50
L
50
20
30
30
30
30
(PPm)
Zr
300
30
200
200
200
200
200
200
(PPm)
N
N
N
N
N
N
N
N
(PPn)
Th
APPENDIX Ib
ANALYTICAL RESULTS (USING SEMI -QUANTITATIVE EMISSION SPECTROSCOPY)
FOR STREAM SEDIMENTS, BATAMOTE MOUNTAINS, ARIZONA
112
AJ024S
AJ027S
AJ028S
AJ029S
AJO30S
AJ019S
AJO2OS
AJ021S
AJ022S
AJ023S
AJ014S
AJ015S
AJ016S
AJ017S
AJ018S
AJ008S
AJOlOS
AJ011S
AJ012S
AJ013S
AJ001S
AJ002S
AJ003S
AJ005S
AJ007S
Sample
1
1
1
2
2
3
2
1
1
1.5
3
3
3
2
2
1
1.5
5
5
3
2
2
1.5
1.5
1.5
2
2
3
3
2
1
3
2
1.5
5
2
2
2
2
2
2
2
1
3
2
2
1
1
3
1.5
1
2
2
1.5
2
1
3
3
1
3
2
1.5
5
70
50
70
70
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
L
L
L
L
L
L
L
L
L
L
0.1
L
0.7
0.5
0.2
0.1
0.1
0.1
0.1
0.1
500
500
500
500
500
700
700
700
500
500
500
700
500
500
500
500
500
500
1000
1000
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
3
2
1.5
1
3
N
N
N
N
N
100
70
70
50
70
N
N
N
N
N
N
N
N
N
N
L
L
L
L
0.2
500
1000
700
700
500
1
0.5
2
5
1.5
1
1.5
1.5
3
B
50
70
50
50
50
70
70
70
70
70
100
50
50
100
70
70
(PPm)
Au
(PPm)
As
(PPm)
Ag
(PPm)
Mn
Ti
(%)
Ca
(%)
Mg
(%)
Fe
(%)
(PPm)
700
700
700
1000
1000
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1.5
1.5
1
1
1.5
1.5
1
1.5
1.5
1.5
1.5
L
L
L
L
L
2
L
2
L
L
L
L
L
L
L
L
L
L
2
2
N
N
N
L
L
Bi
(PPm)
Be
(PPm)
Ba
(PPm)
Appendix Ib -- Analytical Results (Using Semi -Quantitative Emission Spectroscopy) for Stream Sediments,
Batamote Mountains, Arizona
114
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50
30
30
30
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N
N
N
N
100
100
100
100
100
500
500
500
700
700
AJ024S
AJ027S
AJ028S
AJ029S
AJO3OS
30
30
30
30
50
N
N
N
N
N
500
500
500
500
500
AJ019S
AJO2OS
AJ021S
AJ022S
AJ023S
N
N
N
N
N
30
30
30
30
30
30
50
30
30
N
N
N
N
100
100
100
100
100
100
100
100
100
100
500
500
500
500
500
AJ014S
AJ015S
AJ016S
AJ017S
AJ018S
20
30
30
30
30
N
30
100
100
100
100
100
500
500
500
500
500
AJ008S
AJOlOS
AJ011S
AJ012S
AJ013S
(PPm)
Y
(PPm)
W
N
N
N
N
N
100
150
100
100
100
500
500
500
500
500
AJ001S
AJ002S
AJ003S
AJ005S
AJ007S
V
(PPm)
Sr
(PPm)
Sample
Appendix Ib -- continued
L
I_,
I.
L
L
L
L
L
L
L
L
L
L
500
500
500
300
300
200
500
500
200
500
300
200
200
200
200
L
I.
300
200
200
200
300
200
300
200
300
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
(PPm)
(PPm)
100
Th
Zr
L
L
L
L
L
L
L
I.
L
L
(PPm)
Zn
116
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Sr
700
700
700
1000
700
1000
700
700
700
700
700
700
700
700
700
700
700
700
700
1000
1000
700
700
1000
700
AJ036S
AJ037S
AJ038S
AJ039S
AJO4OS
AJ041S
AJ042S
AJ043S
AJ044S
AJ045S
AJ049S
AJ051S
AJ052S
AJ053S
AJ055S
AJ056S
AJ057S
AJ058S
AJ059S
AJO6OS
(PPm)
AJ031S
AJ032S
AJ033S
AJ034S
AJ035S
Sample
100
100
100
100
100
150
150
100
100
100
100
100
150
100
150
150
100
100
150
100
100
100
100
100
100
(PPm)
V
Appendix Ib -- continued
W
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
(PPm)
Y
30
50
50
50
50
30
30
50
30
20
50
30
30
30
30
30
30
50
50
50
30
50
50
30
30
(PPn)
Zn
L
L
L
L
L
L
L
L
L
L
L
L
70
L
L
L
50
L
L
L
L
L
L
L
L
(PPm)
200
200
200
300
300
200
300
300
300
200
200
300
200
200
200
200
200
200
200
200
300
200
500
200
300
(PPm)
Zr
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
(PPm)
Th
119
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500
500
500
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500
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500
1000
700
500
1000
1000
1000
700
700
700
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AJ089S
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AJ061S
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AJ064S
AJ065S
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Sample
150
200
100
100
100
100
100
100
150
150
70
100
100
100
100
100
100
70
100
70
150
100
150
100
150
(PPm)
V
Appendix Ib -- continued
W
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
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30
50
50
30
50
50
50
50
50
30
50
50
50
50
50
50
50
30
30
50
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50
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L
L
L
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L
L
L
50
50
50
L
50
L
L
L
L
L
L
L
L
L
50
I.
(PPm)
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50
50
50
50
(PPm)
100
300
300
300
300
200
200
200
300
100
200
200
200
200
150
300
300
200
150
150
200
200
200
200
200
(PPm)
Zr
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
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122
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700
1000
700
700
700
1000
500
500
700
700
700
700
1000
1000
700
700
700
300
300
300
300
300
300
300
300
AJ096S
AJ097S
AJ098S
AJ099S
AJ100S
AJ101S
AJ102S
AJ103S
AJ104S
AJ105S
AJ106S
AJ107S
AJ141S
AJ142S
AJ143S
AJ148S
AJ149S
AJ150S
AJ153S
AJ154S
(PPm)
Sr
AJO9OS
AJ091S
AJ092S
AJ093S
AJ094S
Sample
70
70
50
50
70
50
70
70
150
150
150
150
100
150
150
150
100
150
150
150
100
100
150
100
150
(PPm)
V
Appendix Ib -- continued
W
N(50)
N(50)
N(50)
N(50)
N(50)
N
N
N(50)
N(50)
N(50)
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
(PPm)
Y
Zr
30
20
20
20
15
15
15
15
50
30
L
N(200)
L(200)
L(200)
L(200)
N(200)
L
L(200)
N(200)
L(200)
L
L
150
200
100
150
300
300
300
150
150
150
200
300
200
200
L
L
300
L
300
300
200
300
300
200
300
300
200
300
(PPm)
30
30
30
30
L
L
L
L
L
L
L
50
L
L
Zn
(PPm)
30
30
30
30
30
30
30
50
30
30
30
(PPm)
Th
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
(PPm)
AJ158S
Sample
2
0.7
Ca
(%)
Mg
(%)
Fe
(%)
Appendix Ib -- continued
1
Ti
0.2
(%)
Ag
(PPm)
N(0.5)
500
Mn
(PPm)
N(200)
N(10)
Au
(PPm)
As
(PPm)
B
50
(PPm)
Ba
500
(PPm)
Be
1
(PPm)
Bi
N(10)
(PPm)
AJ158S
Sample
N(20)
10
Co
(PPm)
Cd
(PPm)
Appendix Ib -- continued
Cr
20
(PPm)
Cu
70
(PPm)
La
50
(PPm)
N
(PPm)
Mo
L
(PPm)
Nb
10
(PPm)
Ni
20
(PPm)
Pb
N(100)
(PPm)
Sb
Sc
7
(PPm)
Sn
N(10)
(PPm)
N
150
N(200)
20
N(50)
50
300
Ba
B
Nb
Ni
Mo
1.a
Y
Zn
Zr
W
V
ppm
ppm
ppm
ppm
ppm
1
20
5
20
5
Cu
ppm
ppm
ppm
ppm
ppm
0.1
50
2
10
20
Ag
As
Au
Mn
Ca
Ti
Cd
Co
Cr
Pb
Sb
Sc
Sn
Sr
ppm
ppm
ppm
ppm
ppm
0.5
2
5
5
10
Be
Bi
%
Z
Z
Z
ppm
0.05
0.02
0.05
0.002
10
Fe
Mg
Element
Lower
Detection
Limit
Element
Lower
Detection
Limit
Element
Lower detection limits (unless otherwise indicated):
10
100
10
50
10
ppm
ppm
ppm
ppm
ppm
5 ppm
5 ppm
100 ppm
Li
Lower
Detection
(PPm)
(PPm)
Th
Zr
(pptn)
Zn
(PPm)
Y
(PPm)
W
(PPm)
V
(PPm)
Sr
L = Detected at levels below the detection limit
N = Not detected at lower detection limit
AJ158S
Sample
Appendix Ib -- continued
Th
Element
100 ppm
Lower
Detection
Limit
APPENDIX Ic
ANALYTICAL RESUTLS (USING SEMI -QUANTITATIVE EMISSION SPECTROGRAPHY)
FOR THE C -3 FRACTION OF HEAVY MINERAL CONCENTRATES,
BATAMOTE MOUNTAINS, ARIZONA
128
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L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
(ppm)
(ppm)
N
Co
Cd
AJ011C3
AJ012C3
AJ013C3
AJ014C3
AJ015C3
Sample
Appendix Ic-- continued
200
200
200
200
200
150
150
200
150
150
200
200
150
100
200
150
100
150
150
200
200
200
200
200
100
(ppm)
Cr
150
200
150
150
200
150
150
150
200
150
150
150
200
150
150
200
150
150
150
150
200
150
150
150
100
(PPm)
Cu
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
(PPm)
La
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
(131m)
Mo
Nb
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
(PPm)
Ni
L
L
20
20
20
L
50
L
50
20
L
L
50
20
L
30
L
L
L
L
L
L
L
L
50
(PPm)
Pb
50
70
50
30
70
70
50
70
2000
70
70
70
50
50
100
70
50
50
200
300
70
100
70
70
20
(PPm)
Sb
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
100
L
L
(PPm)
Sc
30
30
30
30
30
30
20
30
20
20
30
30
30
30
50
30
30
30
30
30
70
50
50
30
20
(PPm)
Sn
50
70
70
30
50
50
70
100
50
50
70
70
70
50
70
50
50
50
50
70
100
150
50
50
30
(PPm)
w
o
300
300
300
300
300
300
300
700
700
300
300
500
500
500
300
300
300
300
300
1000
700
700
700
500
500
AJ016C3
AJ017C3
AJ018C3
AJOI9C3
AJ020C3
AJ021C3
AJ022C3
AJ023C3
AJ024C3
AJ027C3
AJ028C3
AJ029C3
AJ030C3
AJ031C3
AJ032C3
AJ033C3
AJ034C3
AJ035C3
AJ036C3
AJ037C3
(PPm)
Sr
AJ011C3
AJ012C3
AJ013C3
AJ014C3
AJ015C3
Sample
700
700
500
500
300
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
N
N
N
N
N
N
N
N
N
N
N
200
200
300
200
200
200
200
200
200
200
200
200
200
200
200
N
N
N
N
N
N
N
N
500
500
300
500
500
N
N
N
N
N
0(2000)
G(2000)
0(2000)
0(2000)
G(2000)
0(2000)
0(2000)
0(2000)
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
0(2000)
N G(2000)
N G(2000)
N G(2000)
N.G(2000)
N G(2000)
Zr
(PPm)
Zn
(PPm)
N
200
200
200
200
200
200
200
200
200
200
N
N
N
N
N
Y
(PPm)
W
(PPm)
V
(PPm)
Appendix Ic -- continued
Th
N
N
N
N
N
N
L
N
N
L
L
L
L
N
L
N
L
N
N
L
L
N
L
N
N
(PPm)
wt
! -
132
r4
a1
E
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N r*1 u1 C1 u1
N N u1 na N
N N N N C1
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N N N 01 N
M c*1 N N 01
01 M N C1 M
01 M N N N
c'1 cl M M M
M M M M 01
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UUUUU
0 0 0 0 0
UUUUU
C O O 0 0
L
L
N
N
N
N
N
N
N
N
N
AJ058C3
AJ059C3
AJ060C3
AJ061C3
AJ063C3
AJ064C3
AJ065C3
AJ066C3
AJ067C3
AJ068C3
N
N
N
N
N
N
AJ052C3
AJ053C3
AJ055C3
AJ056C3
AJ057C3
L
L
L
L
L
L
L
L
L
L
L
L
L
200
200
200
200
150
200
150
150
200
200
100
150
150
150
150
100
L
I.
200
500
100
200
150
150
100
150
150
150
150
150
150
200
150
150
100
50
150
100
70
150
150
150
300
150
50
100
100
(PPm)
(PPm)
200
200
200
200
200
Cu
Cr
L
L
L
N
N
N
N
N
AJ043C3
AJ044C3
AJ045C3
AJ049C3
AJ051C3
L
L
L
L
L
(PPm)
(PPm)
N
N
N
N
N
Co
Cd
AJ038C3
AJ039C3
AJ040C3
AJ041C3
AJ042C3
Sample
Appendix Ic -- continued
500
700
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
(PPm)
La
N
N
N
N
N
N
N
N
N
N
N
N
L
N
70
N
N
N
N
N
N
N
N
L
N
(PPm)
Mo
100
100
100
100
150
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
(PPm)
Nb
20
L
L
L
10
10
10
10
50
20
10
50
50
50
10
50
20
20
20
20
50
30
L
L
20
(PPm)
Ni
100
50
30
200
100
50
30
30
50
1000
50
300
100
30
50
50
50
50
50
50
50
100
70
50
100
(PPm)
Pb
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
(PPm)
Sb
30
30
50
30
30
50
30
30
30
30
30
50
30
20
50
20
30
20
30
20
50
30
30
30
50
(PPm)
Sc
70
50
50
50
30
150
70
20
30
20
30
30
30
30
50
30
30
30
30
20
50
50
50
30
30
(PPm)
Sn
134
.
z azzz azzzz zzzzz zzzzz z zOa a
Na
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o
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0
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0
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O
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C
0
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00 0000000
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0
0
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0
0
0
0
0
0
0
0
0
0
0
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N N N N N
N N N N N
N N N N Cl
N N N N N
N N N N N
E
F 0,
C3
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v.. .. ..i .v`.
ZZZZZ
zzzzz
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6
6
AJ096C3
AJ098C3
AJ100C3
AJ101C3
AJ102C3
AJ089C3
AJ090C3
AJ091C3
AJ093C3
AJ094C3
AJ081C3
AJ082C3
AJ083C3
AJ085C3
AJ087C3
AJ076C3
AJ077C3
AJ078C3
AJ079C3
AJ080C3
AJ069C3
AJ070C3
AJ072C3
AJ074C3
AJ075C3
Sample
1
0.7
2
2
2
3
10
7
10
10
10
2
1.5
2
2
5
3
3
3
3
3
2
2
2
10
10
10
10
10
0.7
3
0.7
0.7
1.5
1.5
10
2
5
3
10
10
7
10
10
15
1
0.7
1
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
2
1
1
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
C(2)
G(2)
G(2)
10
10
15
10
10
10
10
10
2
G(2)
(%)
Ti
15
10
(%)
Ca
3
2
1
0.7
0.7
5
2
1.5
3
2
1
3
3
1
1
2
(%)
(%)
3
Mg
Fe
Appendix Ic -- continued
500
500
500
500
500
N
500
500
700
700
500
N
N
0.5
N
N
N
N
N
N
N
N
N
N
N
N
2
30
N
N
N
N
N
N
N(0.5)
(PPm)
Ag
700
500
1000
500
300
500
300
500
300
300
1000
200
1000
500
300
(PPm)
Mn
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N(10)
N
N
N
N
(PPm)
Au
N
N
N
N
700
N
N
N
N(200)
N
N
N
N
(PPm)
As
50
50
100
50
100
30
70
50
50
70
20
20
20
20
20
50
30
50
50
50
20
50
70
20
150
(PPm)
B
300
500
1500
500
200
700
300
5000
1500
500
1000
150
700
700
700
200
100
1000
200
1000
150
50
150
500
150
(PPm)
Ba
L
L
N
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
1
N
N
N
L
(PPm)
Be
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N(10)
N
N
N
N
(PPm)
Bi
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
AJ076C3
AJ077C3
AJ078C3
AJ079C3
AJ080C3
AJ081C3
AJ082C3
AJ083C3
AJ085C3
AJ087C3
AJ089C3
AJ090C3
AJ091C3
AJ093C3
AJ094C3
AJ096C3
AJ098C3
AJ100C3
AJ101C3
AJ102C3
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
300
300
500
70
100
100
150
30
150
150
150
300
100
70
100
100
100
150
70
50
50
30
100
100
70
150
100
30
150
700
500
500
500
500
N
N
100
N
500
500
500
500
500
N
L
L
L
N
N
N
N
N
N
N
N
N
L
N
N
N
N(20)
10
L
N
1000
1000
200
500
500
500
500
700
700
700
700
200
500
506
700
Mo
(PPm)
La
(PPm)
Cu
(PPm)
300
100
100
200
300
200
200
20
500
150
50
50
150
150
150
100
70
70
100
200
200
L
L
L
L
L
L
L
L
N(20)
AJ069C3
N
AJ070C3
N
AJ072C3
N
AJ074C3
N
AJ075C3 N(100)
Cr
(PPm)
L
Co
(PPm)
Cd
Sample
(PPm)
Appendix Ic-- continued
Nb
150
200
100
100
100
100
100
100
100
100
100
100
100
100
100
100
150
100
100
100
100
200
100
100
200
(PPm)
Ni
L
L
L
L
L
L
L
L
L
L
L
L
100
L
L
L
L
L
L
L
10
L
L
L
10
(PPm)
Pb
30
50
30
50
200
100
30
2000
300
200
30
30
10
50
20
50
50
50
50
150
70
30
70
50
20
(PPm)
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N(50)
(PPm)
Sb
20
20
30
20
30
30
20
20
20
30
20
N
50
30
20
20
20
20
20
20
30
20
30
50
50
(PPm)
Sc
50
30
50
50
50
50
30
50
50
50
100
20
N
20
50
50
30
50
50
50
70
500
100
N
1000
(PPm)
Sn
w
ch
137
.
E-I
a, '
a
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N
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G.
E
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N
O
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N
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0
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C
N
O
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N
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C
O
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N
O
O
C
N
0
O
O
N
0
O
0
N
i. i. .. i.
C
0
C
N
O
o
o
N
C
C
0
N
O
C
0
N
O
0
0
N
C
0
O
N
O
0
C
N
O
0
O
N
C
0
0
N
C
0
0
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r. ..
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0
N
0
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0
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0
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0
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0
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0
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u1 ul . M u1
u1 in un u'1 u1
u") M ur1 u'1 u1
ZZZZz
ZZZZZ
ZZZZZ
ZZZZZ
CCOCC
N-- N N Cn
O C C O O
o C o C o
OoOu10
N N-+ N
C o o O C
N N N N N
O O O O O
O o O O c
O C O O C
o 0 o O O
-+
zzzzr,OC
.z
u1
o C o o C
ululCO C
N N
C C O O
OOOOC Co000O
cg N N N N
C.`.
>+ E
CO
p.,
M r, M N r`
0 0 0 0 0
o C O 0 0
O O O O O
O 0 o O o
M N i11 M u'1
ul N u1 ur1 in
r, u1 r, r, Grl
M M M M M
CL
M M M M M
U C.J U C) CJ
M M M M M
M M M M M
a)
C
co
C7 CJ U C) CJ
u ) r - c l )
t3
O1 O cg . t ul
O r\ r, r, r-
cif
r, ro
C) U U CJ CJ
N M u1 n
C) CJ U C) U
Q1 C
M,.7
C C O 0 0
O C O O O
un N ul u
un
M M M M M
CJ C) U U C)
O CO CD .-i N
Ch O O C
00000 00000 00000 00000 CT
00.-+-+
r, n t\ r,
co 00 co 00 co
<4
co Oh Oh ch ch
<4 <4 -4 <4 <4
-4 <4 <4 <4 <4
AJ128C3
AJ132C3
AJ103C3
AJ105C3
AJ107C3
AJ117C3
AJ127C3
Sample
1
2
1
2
10
3
5
3
5
2
3
5
3
(X)
(X)
3
Mg
Fe
Appendix Ic -- continued
15
15
30
20
10
15
15
(%)
Ca
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
G(2)
(X)
Ti
2000
2000
700
700
700
5000
5000
(PPm)
Mn
Ag
N(1)
N(1)
N
N
N
N(1)
N(1)
(PPn)
As
L(500)
1000
700
700
N
N
N
(PPm)
Au
N(20)
N(20)
N
N
N
N(20)
N(20)
(PPm)
B
200
200
200
70
50
50
200
(PPm)
Ba
2000
2000
2000
200
700
5000
700
(PPm)
Be
5
5
5
5
L
L
L
(PPm)
Bi
N(20)
N(20)
20
L(20)
N
N
N
(PPm)
N(50)
N(50)
AJ128C3
AJ132C3
70
N
50
N
N(50)
N(50)
N
I.
N
N
30
150
L
N
300
200
500
500
500
500
500
50
N
N
N
N
500
500
500
N
200
L
500
100
100
150
100
100
150
100
50
500
500
500
L
N
200
(PPn)
(PPm)
(PPm)
(PPm)
(PPm)
Nb
(PPm)
Mo
(PPm)
La
Cu
Cr
Co
Cd
AJ103C3
AJ105C3
AJ107C3
AJ117C3
AJ127C3
Sample
Appendix Ic -- continued
Ni
L
L
L
20
20
L
L
(PPm)
150
150
30
700
70
200
200
Pb
(PPm)
200
200
300
200
N
N
N
Sb
(PPm)
N
N
N
N
30
30
30
Sc
(PPm)
Sn
200
50
50
50
100
50
50
(PPm)
2000
2000
AJ128C3
AJ132C3
N(100)
N(100)
N
N
N
N(100)
N(100)
200
200
200
200
200
200
100
(PPm)
W
V
(PPm)
500
500
500
500
500
700
500
(PPm)
Y
G(2000)
G(2000)
G(2000)
G(2000)
G(2000)
N
500
N
N(500)
N(500)
N(500) G(2000)
N(500) G(2000)
(PPm)
(PPm)
Ba
B
Ag
As
Au
Mn
Ca
Ti
Mg
Fe
Element
%
%
%
%
ppm
ppm
ppm
ppm
ppm
ppm
0.1
0.05
0.1
0.005
20
0.2
100
5
20
50
Lower
Detection
Limit
Cu
La
Mo
Nb
Ni
Cd
Co
Cr
Be
Bi
Element
2
50
10
50
10
ppm
ppm
ppm
ppm
ppm
Y
Zn
Zr
W
V
Sc
Sn
Sr
20
200
20
100
20
5
20
10
10
200
Sb
Pb
1
5
10
10
10
ppm
ppm
ppm
ppm
ppm
Limit
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
Lower
Detection
Element
Lower
Detection
Limit
Lower detection limits (unless otherwise indicated):
N
N
L
N
L
N
N
Th
Zr
Zn
(PPm)
L = Detected at levels below the detection limit
N = Not detected at lower detection limit
G = Greater than value shown
300
700
700
1500
2000
(PPm)
Sr
AJ103C3
AJ105C3
AJ107C3
AJ117C3
AJ127C3
Sample
Appendix Ic -- continued
Th
Element
200 ppm
Lower
Detection
Limit
ó
}-,
APPENDIX Id
ANALYTICAL RESULTS (USING SEMI -QUANTITATIVE EMISSION SPECTROGRAPHY)
FOR OXIDE COATINGS ALONG JOINTS AND FRACTURES, BATAMOTE MOUNTAINS, ARIZONA
141
AJ164R
AJ165R
AJ166R
AJ167R
AJ136R
AJ152R
AJ155R
AJ162R
AJ163R
Sample
10
5
2
3
7
5
2
7
10
1
20
15
5
3
0.5
2
3
2
1.5
1.5
15
5
1
1
U.)
(%)
(1)
50
50
50
Ca
Mg
Fe
(PPm)
N(20)
N(20)
N(20)
N(10)
N(10)
N(10)
N(10)
N(10)
N(10)
(PPm)
500
700
L(500)
N(200)
N(200)
N(200)
N(200)
N(200)
N(200)
(pPm)
(PPm)
0.15
0.15
0.2
0.02
G(5000)
G(5000)
G(5000)
1500
5
2
30
1
7
7
1
1
2
Au
As
Ag
Mn
0.2 G(10,000)
0.2 G(10,000)
0.7 G(10,000)
0.1
5000
0.2
G(5000)
(70)
Ti
7
2
2000
1500
2000
150
7
3
5
7
2
2
7
5
7
100
150
100
Bi
(PPm)
2
15
15
100
100
100
100
100
100
500
100
20
Be
(PPm)
5000
1000
2000
700
700
(PPm)
Ba
500
(PPm)
B
Appendix Id-- Analytical Results (Using Semi -Ouantitative Emission Spectroscopy) for Oxide Coatings
Along Joints and Fractures, Batamote Mountains, Arizona
10
10
20
20
20
N(10)
AJ164R
AJ165R
AJ166R
AJ167R
200
500
500
50
700
500
500
200
70
(PPm)
N(50)
N(50)
N(50)
Co
(PPm)
Cd
AJ136R
AJ152R
AJ155R
AJ162R
AJ163R
Sample
Appendix Id-- continued
Cr
100
50
50
100
150
100
200
50
150
(PPm)
Cu
100
100
200
500
2000
2000
3000
500
200
(PPm)
La
Mo
100
200
200
50
50
N(5)
70
70
50
50
100
100
50
100
50
70
(PPm)
200
500
(PPm)
Nb
20
20
20
L(20)
20
20
100
L(50)
L(50)
(PPm)
100
100
100
50
150
100
300
500
70
(PPm)
Ni
200
1000
200
150
1500
1500
1000
700
700
(PPm)
Pb
N(l0)
10
N(10)
30
1000
300
200
20
20
(PPm)
Sb
20
20
30
L(5)
10
5
20
50
20
(PPm)
Sc
Sn
N(10)
N(10)
N(10)
N(10)
N(10)
N(10)
20
100
500
(PPm)
Sr
200
200
200
N(100)
AJ164R
AJ165R
AJ166R
AJ167R
V
150
30
200
200
300
200
500
500
200
(PPm)
W
N(50)
N(50)
N(50)
N(50)
N(100)
N(100)
N(100)
N(50)
N(50)
(PPm)
Y
10
200
150
150
50
10
200
700
50
(PPm)
Zn
500
500
500
L(200)
1500
500
2000
500
500
(PPm)
L = Detected at levels below the detection limit
N = Not detected at lower detection limit
G = Greater than value shown
200
200
200
200
200
(PPm)
AJ136R
AJ152R
AJ155R
AJ162R
AJ163R
Sample
Appendix Id -- continued
300
200
300
50
300
100
500
500
700
(PPm)
Zr
N(100)
N(100)
N(100)
N(100)
N(200)
N(200)
N(200)
N(100)
N(100)
(PPm)
Th
APPENDIX II
ANALYTICAL TECHNIQUES
145
146
Appendix II-- Analytical Techniques
Nitric Acid Extraction (Modified after Ward and others, 1969)
1.
Weigh 0.50 grams of sample into 20 ml disposable test tube containing boiling chip.
2.
Add 2.5 ml of concentrated nitric acid.
3.
Heat for 30 minutes to drive off nitrous oxides.
4.
Dilute to 10 ml with distilled water and bring to a boil.
5.
Cool and centrifuge.
6.
Analyze extract using atomic absorption spectrophotometry (expansion
20).
First Sequential Extraction (T. T. Chao, 1983, personal communication;
modified after Olade and Fletcher, 1974; modified after Filipek and
Owen, 1978)
Oxide Fraction
1.
Weigh 0.50 grams of sample into 50 ml centrifuge tube.
2.
Add 25 ml of.3% oxalic acid, cap and shake.
3.
Heat in preheated block at 100 °C for 15 minutes.
4.
Centrifuge and decant liquid into 50 ml beaker.
5.
Wash and dry remnant sample in test tube.
6.
Evaporate liquid in beaker to dryness.
7.
Place beaker in furnace at 500 °C for 4 hours to burn off oxalic acid.
8.
Dissolve residue in 25 ml of 4 N nitric acid (2.4 N hydrochloric
acid is also adequate) and stir.
9.
Analyze extract using atomic absorption spectrophotometry (expansion
= 50).
Sulfide and Organic Fraction
10.
Add 0.50 grams of potassium perchlorate to remaining sample.
11.
Add 5 ml of concentrated hydrochloric acid.
147
Appendix Il -- continued
12.
Let stand for 30 minutes.
13.
Dilute to 25 ml with distilled water and shake.
14.
Centrifuge.
15.
Analyze extract using atomic absorption spectrophotometry (expansion = 50).
16.
Decant off extract and wash remaining sample.
Crystalline Fraction
17.
Wash sample into 50 ml teflon beaker and evaporate to dryness.
18.
Add 10 ml of concentrated hydrofluoric acid and digest at 120 °C to
dryness.
19.
Add 6 ml of aqua regia (3 parts nitric acid to 1 part hydrochloric
acid), cover and heat to dryness.
20.
Repeat steps 18 and 19.
21.
Extract with 25 ml of 2.4 N hydrochloric acid and stir.
22.
Analyze extract using atomic absorption spectrophotometry (expansion =_50).
Second Sequential Extraction (Modified after
modified after Chao and Zhou, 1983)
Carbonate and Exchangeable Fraction
1.
Weigh 1.00 grams of sample into 50 ml centrifuge tube.
2.
Add 20 ml of 1.0 M acetic acid and agitate for 2 hours in a mechanical shaker.
3.
4.
Centrifuge.
Analyze extract using atomic absorption spectrophotometry (expansion
= 20).
5.
Decant off extract and wash remaining sample.
Easily Reducible Fraction
6.
Add 40 ml of 0.1 N nitric acid to sample and agitate for 30 minutes
148
Appendix Il -- continued
7.
8.
Centrifuge.
Analyze extract using atomic absorption spectrophotometry (expansion
= 40).
9.
Decant off extract and wash remaining sample.
Moderately Reducible Fraction
10.
Add 40 ml of 0.25 M hydroxylamine hydrochloride in 0.25 M acetic
acid and agitate for 30 minutes in a 50 °C water bath.
11.
Centrifuge.
12.
Analyze extract using atomic absorption spectrophotometry (expansion = 40).
13.
Decant off extract and wash remaining sample.
Organic and Sulfide Fraction
14.
Add 15 ml of 30% hydrogen peroxide acidified to a pH of 2.
15.
Heat at 80 °C.
16.
After 1 hour, add an additional 5 ml of acidified 30% hydrogen peroxide.
17.
Continue heating until dry.
18.
Extract with 40 ml of 1 M ammonium acetate in 6% nitric acid for
30 minutes.
19.
Analyze extract using atomic absorption spectrophotometry (expansion = 40).
20.
Decant off extract and wash remaining sample.
Crystalline Fraction
21.
Wash sample into 50 ml teflon beaker and evaporate to dryness.
22.
Add 10 ml of concentrated hydrofluoric acid and digest at 120 °C to
dryness.
23.
Add 6 ml of aqua regia (3 parts nitric acid to 1 part hydrochloric
acid), cover and heat to dryness.
24.
Repeat steps 22 and 23.
149
Appendix II-- continued
25.
Extract with 25 ml of 2.5 N hydrochloric acid and stir.
26.
Analyze extract using atomic absorption spectrophotometry (expansion = 25).
APPENDIX IIIa
ANALYTICAL RESULTS OF THE NITRIC ACID EXTRACTION AND
THE FIRST SEQUENTIAL EXTRACTION ON STREAM SEDIMENTS,
BATAMOTE MOUNTAINS, ARIZONA
150
151
Appendix IIIa -- Analytical Results of the Nitric Acid Extraction and the
First Sequential Extraction on Stream Sediments, Batamote
Mountains, Arizona
Extraction Technique
Sample
Oxalic Acid
HNO3
Cu
Cu
Fe
Cu /Fe
HCl -KC103
(x102)
Cu
.
HF /Aqua Regia
Cu
AJ001S
AJ002S
AJ003S
AJ005S
AJ007S
170
90
140(150)
120(120)
110(130)
47
46
52
51
52
3800
3600
3300
5300
3200
1.24
1.28
1.58
0.96
1.63
106
21
51
33
AJ008S
AJOlOS
AJO11S
AJ012S
AJ013S
190(180)
130(140)
60(70)
76
67
4300
5100
1.77
1.31
61
36
13
90
140
32
44
3300
3800
0.97
1.14
33
38
16
110
100
140
130
160
46
35
63
53
64
3900
3400
4800
4700
3600
1.18
1.03
1.31
1.13
1.78
36
35
41
58
10
16
10
AJ014S
AJ015S
AJ016R
AJ017S
AJ018S
43
43
AJ019S
AJO2OS
AJ021S
AJ022S
AJ023S
280
160
170(180)
130
200
109
66
2600
3500
4.19
104
1.89
50
--
53
105
4800
6100
1.10
1.72
39
67
AJ024S
AJ027S
AJ028S
AJ029S
AJO3OS
150
150
140
170(180)
130(130)
55
54
55
3600
4100
4500
1.53
1.32
1.22
48
51
43
64
5400
42
8700
29
6000
37 10,300
6400
50
1.19
0.48
0.48
0.36
0.78
45
4000
3300
4100
4100
1.40
2.27
2.56
61
AJ031S
AJ032S
AJ033S
AJ034S
AJ035S
AJ036S
AJ037S
AJ038S
AJ039S
AJO4OS
150
90
80
80
130
110(110)
160
200
230
170
56
75
105
70
1.71
18
24
30
20
15
39
80
85
62
15
15
13
12
152
Appendix IIIa- continued
Extraction Technique
Sample
Oxalic Acid
HNO3
AJ041S
AJ042S
AJ043S
AJ044S
HF /Aqua Regia
HC1 -1(C10
3
(x102)
Cu
Cu
60
14
Cu
Cu
Fe
160
140
76
79
33
38
28
4700
4800
6200
7600
7700
1.62
1.65
0.53
4700
6200
6900
6200
4700
0.70
0.65
0.72
0.71
0.51
25
26
42
16
8
8000
4100
44 10,700
7500
37
8500
38
0.69
27
63
12
0.62
0.77
0.53
0.71
0.43
21
31
Cu /Fe
36
22
32
A.J045S
75
95
80
AJ049S
AJ051S
AJ052S
AJ053S
AJ055S
95
33
110
130
120
60
40
50
AJ056S
AJ057S
AJ058S
AJ059S
AJO6OS
120
150
100
95
90
55
58
AJ061S
AJ063S
AJ064S
AJ065S
AJ066S
70
80
70
110
70
26
23
44
26
4200
3500
4300
6000
6100
AJ067S
AJ068S
AJ069S
AJO7OS
AJ072S
120
70
46
27
20
22
22
5800
6200
4300
6800
4300
0.79
0.44
0.47
0.32
0.51
42
25
AJ074S
AJ075S
AJ076S
AJ077S
AJ078S
50
5200
6200
4800
17 12,200
4500
18
0.50
0.45
0.44
0.14
0.40
11
16
14
AJ079S
AJO8OS
AJ081S
AJ082S
AJ083S
40
5700
4600
7000
9400
4100
0.23
0.28
0.30
0.18
0.24
10
12
50
60
55
65
55
40
50
44
24
27
26
28
21
45
55
45
13
13
21
17
30(25)
10
0.50
0.36
1.41
0.41
0.49
0.45
21
19
44
22
25
20
18
33
24
15
18
30
16
1]
13
9
9
3
17
153
Appendix IIIa-- continued
Extraction Technique
Sample
Oxalic Acid
HNO3
Cu
Fe
40
35
7800
5300
0.51
0.66
30
75
33
5400
0.61
28
70
33
30
7100
4400
0.46
0.68
23
26
23
7100
4700
0.32
0.28
16
13
9100
0.25
19
24 10,100
0.24
17
Cu
AJ084S
AJ085S
AJ087S
AJ088S
AJ089S
HC1 -KC103
30(25)
80
80(70)
80(70)
Cu /Fe
(x102)
Cu
95(100)
90(90)
55
40
AJ096S
AJ097S
AJ098S
AJ099S
AJ100S
60(55)
70(50)
60(60)
70(50)
60
23
21
9700
0.22
15
AJ101S
AJ102S
AJ103S
AJ104S
AJ105S
70
70
30
23
13
0.35
0.26
0.18
20
35(35)
45(45)
50(40)
8600
8800
7100
19
6300
0.30
13
65
95
75
75
28
45
46
50
5300
4000
3600
3400
0.53
24
1.13
1.28
1.47
49
80
55
63
70
80
67
4000
3400
2800
2600
2800
1.38
1.85
54
52
60
71
64
AJ148S
AJ149S
AJ150S
AJ153S
AJ154S
11
16
10
--
19
17
60(60)
100
130
130
140
Cu
16
AJO9OS
AJ091S
AJ092S
AJ093S
AJ094S
AJ106S
AJ107S
AJ141S
AJ142S
AJ143S
HF /Aqua Regia
2.50
3.08
2.39
42
42
All values in parts per million unless otherwise indicated.
Parantheses indicate duplicate analyses.
14
APPENDIX IIIb
ANALYTICAL RESULTS OF THE SECOND SEQUENTIAL EXTRACTION
ON STREAM SEDIMENTS, BATAMOTE MOUNTAINS, ARIZONA
154
Density
Separate
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Sample
AJ012S
AJ015S
AJ019S
AJ038S
AJ039S
13
70
65
40
12
20
9
6
18
18
22
20
59
13
52
19
26
56
46
25
11
18
50
60
70
50
65
50
45
40
90
60
75
56
16
14
55
13
65
33
24
57
36
25
61
200
118
40
114
305
41
46
67
31
160
139
142
300
31
129
121
113
270
61
65
200
62
61
260
66
46
50
49
46
52
45
19
13
50
12
15
6
35
60
4
19
40
11
30
4
12
14
28
40
13
52
6
15
23
35
30
39
125
75
27
40
40
30
30
29
180
65
35
120
49
38
17
51
22
12
14
64
27
17
500
3000
1100
300
400
2800
1400
500
400
1400
700
400
400
1600
600
200
400
1900
600
400
15
20
80
45
55
20
80
20
15
25
60
40
75
35
45
100
65
40
50
50
Moderately Reducible
Cu
Fe
Mn
45
30
125
35
25
30
30
35
40
65
40
35
40
50
50
Mineralogie Fraction
Easily Reducible
Cu
Fe
Mn
23
Carbonate /Exchangeable
Cu
Fe
Mn
Appendix IIIb-- Analytical Results of the Second Sequential Extraction on Stream Sediments, Batamote
Mountains, Arizona
Density
Separate
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Sample
AJ012S
AJ015S
AJ019S
AJ038S
AJ039S
9
14
480
360
38
9
240
520
33
32
460
200
52
4
15
180
10
1
39
240
90
1950
580
60
17,000
65,000
51,000
10,000
18,000
95,000
45,000
13,000
82
32
44
105
77
36
15
420
1500
1100
290
450
1450
1100
310
1200
580
40
15,000
105,000
31,000
12,000
54
10
25
25
10
430
1350
1100
580
25
10
20
10
10
20
30
26,000
290,000
40,000
18,000
46
46
95
115
40
115
58
26
105
10
25
20
10
220
500
280
170
95
1950
280
45
70
100
220
2450
440
65
18,000
270,000
41,000
13,000
34
59
66
22
140
2650
340
Mn
15
25
30
10
Fe
320
750
740
230
Cu
Mineralogic Fraction
Crystalline
Sulfide /Organic
Mn
Fe
Cu
Appendix IIIh- continued
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
AJO4OS
AJ049S
AJ069S
AJ094S
AJ103S
Chrysocolla
Standard
Density
Separate
Sample
50
40
13
120
12
17
5
9
230
2
14
10
36
240
2
7
21
2
23
11
2
130
2
20
2
6
13
2
15
160
5
2
15
2
5
5
45
180
60
50
45
130
55
45
45
170
65
45
19
45
150
22
14
5
12
15
40
16
27
62
23
17
68
93
12
5
110
485
73
82
340
91
98
335
76
68
350
62
49
74
290
89
60
5
9
4
9
7
4
7
9
8
8
11
53
23
65
75
27
31
40
14
54
7
45
55
40
40
L(5)
60
60
50
50
8
35
20
6
17
8
21
6
14
27
22
10
24
14
42
35
17
110
70
25
31
N(100)
1500
5800
2000
1300
40
700
3000
1100
500
N(5)
75
85
90
135
30
19
140
30
90
135
20
600
3800
800
200
55
115
135
30
95
70
40
50
,
800
3800
900
400
400
2000
1000
400
Moderately Reducible
Fe
Mn
Cu
45
60
40
50
90
40
40
50
30
25
35
Mineralogic Fraction
Easily Reducible
Mn
Fe
Cu
15
41
Carbonate /Exchangeable
Mn
Fe
Cu
Appendix Illb -- continued
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
Bulk
Heavies
Slimes
Lights
AJO4OS
AJ049S
AJ069S
AJ094S
AJ103R
21
7
3
18
36
3
2
35
19
7
4
41
40
6
4
63
80
8
5
460
250
80
450
610
890
400
410
420
720
370
360
450
420
230
420
730
1050
390
340
1250
980
250
15
N(5)
20
30
40
20
15
20
20
40
25
10
15
15
35
15
30
15
10
20
30
5
17
29
70
52
26
52
48
22
75
22
60
28
43
100
64
30
44
90
125
36
Cu
L(1000)
28,000
330,000
43,000
17,000
19,000
75,000
60,000
17,000
23,000
115,000
55,000
15,000
26,000
85,000
44,000
21,000
17,000
65,000
50,000
13,000
Fe
Mineralogie Fraction
Crystalline
Sulfide /Organic
Cu
Fe
Mn
All values in parts per million.
Chrysocolla
Standard
Density
Separate
Sample
Appendix IIIb -- continued
L(5)
170
3050
270
60
90
960
680
70
70
2400
760
120
200
1500
150
130
85
560
85
1250
Mn
APPENDIX IIIc
ANALYTICAL RESULTS (USING NITRIC ACID EXTRACTION) FOR COPPER
IN THE C -1 AND C -2 FRACTIONS OF HEAVY MINERAL CONCENTRATES,
BATAMOTE MOUNTAINS, ARIZONA
159
160
Appendix IIIc-- Analytical Results (Using Nitric Acid Extraction) for
Copper in the C -1 and C -2 Fractions of Heavy Mineral
Concentrates, Batamote Mountains, Arizona
C -2
Sample
55
AJO81C
AJ082C
AJ083C
AJ085C
AJ087C
20
20
50
55
30
100
AJ089C
AJ090C
AJ091C
AJ093C
AJ094C
65
AJ058C
AJ059C
AJ060C
AJ061C
AJ063C
55
65
60
55
45
AJ096C
AJ098C
AJ100C
AJIOIC
AJ102C
AJ028C
AJ029C
AJ030C
AJ031C
AJ032C
70
45
50
60
50
AJ064C
AJ065C
AJ066C
AJ067C
AJ068C
25
AJ103C
AJ105C
AJ107C
AJ033C
AJ034C
AJO35Ç
AJ036C
AJ037C
45
70
55
50
65
AJ069C
AJ070C
AJ072C
AJ074C
AJ075C
120
85
45
AJ076C
AJ077C
AJ078C
AJ079C
AJ080C
C -2
Sample
45
20
AJ043C
AJ044C
AJ045S
AJ049C
AJ051C
45
60
55
60
55
AJ052C
AJ053C
AJ055C
AJ056C
AJ057C
AJ021C
AJ022C
AJ023C
AJ024C
AJ027C
65
Sample
AJ011C
AJ012C
AJOI3C
AJ014C
AJ015C
AJ016C
AJ017C
AJ018C
AJO19C
AJ020C
AJ038C
AJ039C
AJ040C
AJ041C
AJ042C
C -1
85
35
50
35
90
70
50
70
55
260
90
75
50
55
All values in parts per million.
C -1
60
20
50
20
15
--
20
25
30
40
20
50
15
45
15
10
15
10
10
25
10
25
10
20
C -1
C -2
15
20
60
40
35
15
25
20
15
25
25
\20
30
30
15
15
20
REFERENCES
Barton, H. N., Theobald, P. K., Turner, R. L., Eppinger, R. G.,
and Frisken, J. G., 1982. Geochemical data for the Ajo two degree
quadrangle, Arizona. U.S. Geological Survey Open File Report
82 -419.
119 p.
Bryan, K., 1925. The Papago country, Arizona.
Survey Water -Supply Paper 499. 436 p.
U.S. Geological
Chao, T. T., and Zhou, L., 1983. Extraction techniques for selective
dissolution of amorphous iron oxides from soils and sediments.
Soil Science Society of America Journal, 47, p. 225 -232.
Cooper, J. R.
Bismuth in the United States. U.S. Geological
Survey Mineral Inventory Resource Map MR -22. 19 p., 1 sheet.
DeKalb, C., 1918.
Ajo copper mine.
Mining and Science Press, 116,
p. 115 -116 and 153 -156.
Dixon, D. W., 1966. Geology of the New Cornelia mine, Ajo, Arizona.
In: Titley, S. R., and Hicks, C. L., eds. Geology of the
Porphyry Copper Deposits -- Southwestern North America, p. 123 -132.
Filipek, L. H., and Owen, R. M., 1978. Analysis of heavy metal
distributions among different mineralogical states in sediments.
Canadian Journal of Spectroscopy, 23, p. 31 -34.
Gilluly, J., 1935. Ajo district (Arizona).
In: Copper Resources
of the World, 16th International Geological Congress, 1,
p. 228 -233.
1937.
Geology and ore deposits of the Ajo quadrangle, Arizona.
Arizona Bureau of Mines Geological Series, No. 9,
Bull. 141.
83 p.
,
1942.
The mineralization of the Ajo copper district, Arizona.
Economic Geology, 37, p. 247 -309.
,
1946.
The Ajo mining district, Arizona.
Survey Professional Paper 209. 112 p.
,
U.S. Geological
Grimes, D. J., and Marranzino, A. P., 1968. Direct- current and
alternating- current spark emission spectrographic field for the
semi -quantitative analysis of geological materials. U.S.
Geological Survey Circular 591. 6 p.
161
162
Harris, J. 0., 1984. Emplacement and crystallization of the Cornelia zoned pluton, Ajo, Arizona: An analysis based on compositional zoning of plagioclase and field relations. Unpublished
M.S. Thesis, The University of Arizona. 78 p.
Haxel, G., Wright, J. E., May, J. E., and Tosdal, R. M., 1980.
Reconnaissance geology of the Mesozoic and Lower Cenozoic rock
of the Southern Papago Indian Reservation: A preliminary report.
Arizona Geological Society Digest, 12, p. 17 -29.
Ingham, G. R., and Barr, A. T., 1932. Mining methods and costs at
the New Cornelia Branch, Phelps Dodge Corporation, Ajo, Arizona.
U.S. Bureau of Mines Information Circular 6666. 18 p.
Jones, W. C., 1974. General geology of the northern portion of the
Ajo Range, Pima County, Arizona. Unpublished M.S. Thesis,
The University of Arizona. 77 p.
American
The Ajo copper mining district.
Joralemon, I. B., 1914.
Institute of Mining, Metallurgical and Petroleum Engineers
Transactions, 49, p. 593 -610.
Kahle, K., Conway, D., and Haxel, G., 1978. Preliminary geologic
map of the Ajo 1° by 2° quadrangle, Arizona. U.S. Geological
Survey Open File Report 78 -1096. 2 sheets.
Klein, D. P., 1982. Residual aeromagnetic map of the Ajo and
U.S.
Lukeville 1° by 2° quadrangles, southwestern Arizona.
Geological Survey Open File Report 82 -599. 1 sheet.
Introduction to Exploration Geochemistry.
Levinson, A. A., 1980.
Second edition, 924 p.
May, D. J., Peterson, D. W., Tosdal, R. M., LeVeque, R. A., and
Miller, R. J., 1981. Miocene volcanic rocks of the Ajo Range,
In: Tectonic Framework of the Mojave
south -central Arizona.
and Sonoran Deserts, California and Arizona, p. 65 -66.
Annual
National Oceanic and Atmospheric Administration, 1981.
19 p.
Summary of Climatalogical Data for Arizona, No. 13.
Nie, N. H., Hull, C. H., Jenkins, J. G., Steinbrenner, K., and
Bent, D. H., 1975. Statistical Package for the Social Sciences.
675 p.
Olade, M., and Fletcher, K., 1974. Potassium chlorate -hydrochloric
acid: A sulfide selective leach for bedrock geochemistry.
Journal of Geochemical Research, 3, p. 337 -344.
163
Raines, G. L., and Theobald, P. K., 1981. Remote sensing in the
Ajo 1° by 2° quadrangle, Arizona. In: Geological Survey Research, 1981. U.S. Geological Survey Professional Paper 1275,
p. 21 -22.
Shafiqullah, M., Damon, P. E., Lynch, D. J., Reynolds, S. J.,
Rehrig, W. A., and Raymond, R. H., 1980. K -Ar geochronology
and geologic history of southwestern Arizona and adjacent
areas.
Arizona Geological Society Digest, 12, p. 201 -260.
Theobald, P. K., and Barton, H. N., 1983. Statistical parameters
for resource evaluation of geochemical data from the Ajo 1° by
2° quadrangle, Arizona.
U.S. Geological Survey Open File Report
83 -734.
44 p.
Wadsworth, W. B., 1968. The Cornelia pluton, Ajo, Arizona.
Economic Geology, 63, p. 101 -115.
Ward, F. N., Nakagawa, H. M., Harms, T. F., and VanSickle, G. H.,
1969.
Atomic- absorption methods useful in geochemical exploration.
U.S. Geological Survey Bulletin 1289. 45 p.
Wedepohl, K. H., ed., 1969.
Handbook of Geochemistry.
Wilson, E. D., Moore, R. T., and Cooper, J. R., 1969.
Map of Arizona.
1 sheet.
6 vols.
Geologic
112°50'
4
112° 40'
DESCRIPTION OF UNITS
r
4
Z
OW
32°30
Qa
QUATERNARY ALLUVIUM. POORLY SORTED
NSIVE
AND
VALLEY FILL. CEMENTED IN PLACES BY
BYEXTENSIVE
EXTENSIVE CALICHE
DEVELOPMENT.
1-
32° 30'
QTa
UNCONSOLIDATED ALLUVIUM PREDATING Oa. FORMS SINUOUS LOW
MOUNDS IN THE NORTH AND DISSECTED PEDIMENTS IN THE
SOUTH.
Tbi
BATAMOTE ANDESITE, INTRUSIVE UNIT. APHANI TIC TO FINE
GRAINED HYPERSTHENE OLIVINE ANDESITE. OCCURS IN TWO
DISTINCT PHASES A FINE GRAINED SALT AND PEPPER
HYPERSTHENE OLIVINE ANDESITE AND A WEAKLY PORPHYRITICAPHANITIC OLIVINE ANDESITE. WEATHERS GRAY TO YELLOW
ON OUTCROP.
Tba
Tba
rc
BASALTIC ANDESITE WITH HIGHLY VARIABLE TEXTURES.
OCCURS IN FLOWS UP TO 50 FEET THICK, AS A TUFF AND
A VOLCANIC BRECCIA. THE FLOWS TYPICALLY GRADE
UPWARDS FROM A GRAY APHANITIC COARSELY FISSILE
SECTION, THROUGH A MASSIVE INTERMEDIATE ZONE, AND INTO
A HIGHLY VESICULAR UPPER SECTION. ALSO INCLUDES
MINOR VOLCANOCLASTIC SEDIMENTS. WEATHERS GRAY, YELLOW,
MAROON AND BLACK ON OUTCROP.
H
Qa
BATAMOTE ANDESITE, EXTRUSIVE UNIT. APHANITIC OLIVINE
lTb ,I BATAMOTE ANDESITE, VENT FACIES. RED TO MAROON VOLCANIC
BECCIA. TEN CENTIMETER TO ONE METER BLOCKS IN A RED,
OXIDIZED, VESICULAR, APHANITIC TO MEDIUM GRAINED
ANDESITIC GROUNDMASS.
w
II
l
1111
r
Tai
CHILDS LATITE. FLOW BANDED PORPHYRI TIC AUGITE LATITE.
TYPICALLY PORPHYRITIC -APHANITIC WITH SUB- TO ANHEDRAL,
MEDIUM TO COARSE 'GRAINED POTASSIC FELDSPAR PHENOCRYSTS
IN A PINK APHANITIC GROUNDMASS. FORMS FLOWS UP TO 80
FEET_ THICK. LAHARIC BRECCIA ALSO PRESENT. WEATHERS
FROM WHITE TO MAROON ON OUTCROP. FORMS ROUNDED,
POINTED HILLS.
.
112'50
3025
32° 25'
iN
EXPLANATION:
CONTACT, DASHED WHERE APPROXIMATE
OR UNCERTAIN, DOTTED WHERE
COVERED.
FAULT, DASHED WHERE APPROXIMATE OR
UNCERTAIN, DOTTED WHERE COVERED.
,a.
ATTITUDE
45"
O
2
O
2
112° 40'
4
3
3
4
5 KILOMETERS
SCALE: 1:62500
PLATE I- SKETCH GEOLOGIC MAP,
BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
g.ha i4itËeve cP, adFnsr 'Room
DEPART
UNIVERSITY
:
GEOSCIcNCES
FSZJNA
MILES
112° 50'
45'
112° 40'
I
32° 30'
32° 30'
112° 50'
EXPLANATION:
N
/
32°25'
32° 25'
0e--/ LINE OF EQUAL CONCENTRATION
ON PPM)
BOUNDARY OF SAMPLED AREA
45'
112 °40'
3
1
0
1
2
3
4
4
MILES
5 KILOMETERS
SCALE: 1:62500
PLATE 10-COPPER, LEACHED USING POTASSIUM PERCHLORATE AND
HYDROCHLORIC ACID, SEQUENTIALLY AFTER AN OXALIC ACID LEACH,
FROM -30 MESH STREAM SEDIMENT, BATAMOTE MOUNTAINS, ARIZONA
N,
AEevt
/Ceadinff
DEPARTMENT 0F GEOSCIENCES
UNIVERSITY OF ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1964
112° 40'
45
112° 50'
32° 30'
112°50'
i
EXPLANATION:
/1
LINE
32° 25
F EQUAL CONCENTRATION
BOUNDARY OF SAMPLED AREA
112° 40'
4
0
1
1
0
1
2
3
4
MILES
5 KILOMETERS
SCALE : 1:62500
PLATE 1 I- COPPER, LEACHED USING NITRIC ACID,
IN THE C -2 FRACTION OF HEAVY MINERAL CONCENTRATES,
BATAMOTE MOUNTAINS, ARIZONA
`:7h. 04"ntevs %Ceading( Wooers
OEPARTI'ÍLNT OF GEOSCIENCES
UNIVERSITY OF ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
112°50'
45'
112° 40'
32° 30
32° 30
112° 50'
EXPLANATION:
N
/
32 °251
32° 25'
°o' LINE OF EQUAL CONCENTRATION
(IN PPM)
./ BOUNDARY OF SAMPLED AREA
112° 40'
45'
0
1
1
2
1
O
1
2
4
3
3
4
MILES
5 KILOMETERS
SCALE: 1:62500
PLATE 12- COPPER IN THE C -3 FRACTION OF HEAVY
MINERAL CONCENTRATES, BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
CAlevs 9eaC>!inff
DEPARTP? i'il
UNIVERSI-fiY
'
or
/'Coon.
G[OSCIENCES
;,RiZOt`iA
112° 50'
45,
112° 40'
32° 30'
112° 50'
i
EXPLANATION
N
ELEMENT
32 °25'
CONCENTRATION RANGES
(PPM)
1
Ag
As
Ba
L(0.2) -10
L(100)-500
2000 -5000
200
Cu
L(10)-50
Mo
Pb
200 -500
L(20)
100-300
Sb
Sn
L(100) -500
Zn
2
15 -30
700
7000 -10,000
300
70-100
700 -2000
20 -100
500-1000
OANOMALOUS DRAINAGE BASIN
"°. BOUNDARY OF SAMPLED AREA
45,
3
2
1
0
1
2
3
4
5 KILOMETERS
SCALE: 1:62500
PLATE 13- ANOMALOUS SILVER, ARSENIC, BARIUM, COPPER, MOLYBDENUM,
LEAD, ANTIMONY, TIN AND ZINC IN THE C -3 FRACTION OF HEAVY
g %a Ctnfç-vF lrCeading' WoQm
DEPARTNE:N
GEOSCIENCES
UNIVERSITY OF ARIZONA
MINERAL CONCENTRATES, BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
45'
112 °50'
112° 40'
t
\\
32° 30'
i- 32° 30'
J
>
---\..,-.r.--
>
,
_
--1./
.;
..
i
f/
r-..J
\\
l
EXPLANATION:
N
..
32° 25'
\
SAMPLE SITE
o
WASH
MINERALS PRESENT
PYRITE
i
\
V COVELLITE
OARSENOPYRITE
1
1
..
..
1
`.
. .
- _ _;r -e...
--(.
i:
1
\
ti
\.. \
1
. ---.
2
2
4
o
^..¡
i
_
/
),.:<-
.
Y ..
I
/
/
112 °40
4
MILES
5 KILOMETERS
PLATE 14- PYRITE, CHALCOPYRITE, MALACHITE, COVELLITE AND
ARSENOPYITE IN THE C -3 FRACTION OF HEAVY MINERAL CONCENTRATES,
BATAMOTE MOUNTAINS, ARIZONA
/Q.4lidlMff ROCYH
pEF'AR`i`WhlÌ' (.', G"._OSCIENCES
UIdIVERSIT! OF ARIZONA
.,-
\/
SCALE: 1:62500
;14ntdVr
32 °25'
:\
45'
3
3
/
.1
l
L_..
/
\.
-,
---
1
._
.
?
.J
.. --
._ --
(-/*- -)
1
1
0
.
\
-
.).
`
S
../
''
.
.
i-
.:-. .-...--
"N..------
/
O
)
.
\.
MALACHITE
1
--
.
.0 CHALCOPYRITE
A
.:
.
._
112 °50'
:
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
45,
112° 50'
112° 40'
'r~`.
32° 3Ó
r
`o
»
.
..
I
:
%
)4
. , !-
.
-- (
r
'
-
11
f
/
Os..
-.
112°50'
EXPLANATION:
32° 25'
o SAMPLE SITE
r r WASH
MINERALS PRESENT
BARITE
A
V
O
CERRUSITE
GALENA
LEAD SHOT
WULFENITE
O
CASSITERITE
r\
45'
2
O
0
1
2
4 MILES
3
3
4
5
KILOMETERS
SCALE: 1:62500
PLATE 15- BARITE, CERUSSITE, GALENA, LEAD SHOT, WULFENITE AND
CASSITERITE IN THE C-3 FRACTION OF HEAVY MINERAL CONCENTRATES,
43.4
,gevs leading
DEPARTfa9 i ï ; GEOSCIENCES
UNIVERSITY OF ARIZONA
BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
45
112 °50'
157
147
32°3d
+
15'4E152
1
56
112° 40'
1s5
161
159
160A, B
54
6
138
137A-D
32° 30'
±A,48
47
46
50
71A,B
i133
135
4
134
136
25
4126
73
12944131
130
.113
122
111
112
11162
110
120 123
121g
9
140
109A,B
119,118
139
86A.
£144
£108
146
124
164 125
126
62
165
112° 50'
32 °25'
3 2° 25'
N
/1166
EXPLANATION:
95
25 ROCK CHIP
136. OXIDE COATING
115 116
114
167
O
1
1
0
1
2
112 °40'
45"
3
2
1
3
4
4 MILES
5 KILOMETERS
SCALE: 1:62500
PLATE 2 -ROCK CHIP AND OXIDE COATING SAMPLE SITES
BATAMOTE MOUNTAINS, ARIZONA
'JAe C4intevs 92eading ieoarw
DEPARTMENT ,.;= GEOSCIENCES
- UNIVERSITY OF ARIZONA
DAt/ID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF AR ZONA, 1984
j
t\
32 °30
\
40
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EXPLANATION:
\
SAMPLE SITE
.1
i
1
O
1
.
o - -_ i'
/
DEPART:T (=7
GEOSCIENCES
UNIVERSITY OF 'r, rILONA
Í
i/
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)
182(
.
:.
-
32° 25
1. --..
.
2
3
4
107 :
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106117
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4 MILES
3
2
(
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5 KILOMETERS
SCALE: 1:62500
ghe nEevs eadin8 /oam
\
79
94 96,9%
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7
112° 4d
45,
112 °50'
PLATE 3- DRAINAGE MAP SHOWING STREAM SEDIMENT
AND HEAVY MINERAL CONCENTRATE SAMPLE SITES,
BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
45'
112° 50'
40
112° 40'
.39
+
/,_,720
32° 30
11
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N
EXPLANATION:
104
!
81
r"-82
\3
32° 25'
94 96,97
7
SAMPLE SITE
DRAINAGE BASIN BOUNDARY
112 °40'
45,
o
1
0
1
2
4
3
2
1
3
4
5
MILES
KILOMETERS
SCALE: 1 :62500
PLATE 4- STREAM SEDIMENT AND HEAVY MINERAL CONCENTRATE
SAMPLE SITES, SHOWING AREAS OF INFLUENCE,
BATAMOTE MOUNTAINS, ARIZONA
431'¢ .a4ritevg CPeading 92oa,y
DEPAR M;
CEúSCIENCES
11fVIVFRSITY OF ARI7nNa
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
112°50'
112°40'
45,
32° 30
112° 50
EXPLANATION:
N
32° 25
LINE OF EQUAL CONCENTRATION
(IN PPM)
BOUNDARY OF SAMPLED AREA
1
0
0
1
2
4 MILES
3
2
1
3
4
5 KILOMETERS
SCALE: 1:62500
4Eí4'4a
riti
UNIVERSITY
PLATE 5- COPPER, LEACHED USING NITRIC ACID,
FROM -30 MESH STREAM SEDIMENT,
BATAMOTE MOUNTAINS, ARIZONA
ding 9eoóm
CF
OF ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
112 °50'
45
112° 40'
32 °30'
32 °30
112° 50'
i
EXPLANATION:
N
//
32° 25'
32° 25'
BOO/ LINE OF EQUAL CONCENTRATION
(IN PPM)
BOUNDARY OF SAMPLED AREA
45,
0
1
1
2
1
0
1
2
112 °40'
4
3
3
4
MILES
5 KILOMETERS
SCALE: 1:62500
PLATE 6 SILVER IN -30 MESH STREAM SEDIMENT,
`1e cAtevs
DEPlR7ivi{i7
eading
j
,COOn,
GEOSCIcNCES
UNIVERSITY
OFCARIZONA
,-
BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
112 °40
45,
112 °50
32 °30/
112 °50'
EXPLANATION:
N
y
/
32 °25
° LINE OF EQUAL CONCENTRATION
(IN PPM)
BOUNDARY OF SAMPLED AREA
112°40'
O
1
1
0
1
4 MILES
2
1
2
3
4
5 KILOMETERS
SCALE: 1 :62500
PLATE 7- BISMUTH IN -30 MESH STREAM SEDIMENT,
BATAMOTE MOUNTAINS, ARIZONA
é cri
cvs Vading Woon
DEPARTM_NT CF. GEOSCIENCES
UNIVERSITY OF ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIECES
UNIVERSITY OF ARIZONA, 1984
45,
112°50'
112° 45'
32° 30'
EXPLANATION
N
ELEMENT
32 °25
CONCENTRATION
(PPM)
1
Mo
Pb
Sn
Zn
L(5)-5
100-150
L(5) -5
50
RANGES
2
7 -10
200 -300
7 -10
70
OANOMALOUS DRAINAGE BASINS
BOUNDARY OF SAMPLED AREA
0
1
1
0
1
2
3
4
5 KILOMETERS
SCALE: 1:62500
PLATE 8- ANOMALOUS MOLYBDENUM, LEAD, TIN AND ZINC
IN -30 MESH STREAM SEDIMENT, BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON, DEPARTMENT OF GEOSCIENCES
4
isadevs Weadi»
t7
DEPARTrviIPT ;;,-
UNIVERSITY OF ARIZONA
UNIVERSITY OF ARIZONA, 1984
Coo
112° 50'
45,
112° 40'
32° 30
32° 30'
112° 50'
EXPLANATION:
32° 2
32°25'
N
°°
LINE OF EQUAL CONCENTRATION
RATIOS (Cu /Fe x 10 -2)
BOUNDARY OF SAMPLED AREA
45'
O
1
1
1
0
2
1
112°40'
4 MILES
3
2
3
5 KILOMETERS
SCALE: 1:62500
PLATE 9- COPPER (NORMALIZED TO IRON), LEACHED USING OXALIC ACID,
FROM -30 MESH STREAM SEDIMENT,
ghe :4nfevs `12eading %ooI
DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA
BATAMOTE MOUNTAINS, ARIZONA
DAVID LOWELL HUSTON,
DEPARTMENT OF GEOSCIENCES
UNIVERSITY OF ARIZONA, 1984
THE SIGNIFICANCE OF A WIDESPREAD STREAM SEDIMENT COPPER ANOMALY
IN THE BATAMOTE MOUNTAINS, PIMA COUNTY, ARIZONA
by
David Lowell Huston
A Thesis Submitted to the Faculty of the
DEPARTMENT OF GEOSCIENCES
In Partial Fulfillment of the Requirements
For the Degree of
MASTER OF SCIENCES
In the Graduate College
THE UNIVERSITY OF ARIZONA
1
9 8 4
STATEMENT BY AUTHOR
This thesis has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is
deposited in the University Library to be made available to borrowers
under the rules of the Library.
Brief quotations from this thesis are allowable without special
permission, provided that accurate acknowledgement of source is made.
Requests for permission for extended quotation from or reproduction of
this manuscript in whole or in part may be granted by the head of the
major department of the Dean or the Graduate College when in his or her
judgement the proposed use of the material is in the interests of
In all other instance however, permission must be
scholarship.
l
n
obtained from the author.
SIGNED:
APPROVAL BY THESIS DIRECTOR
This thes
Ms been approved
f
S. R. TITLEY
Professor of Geosciences
the date shown below:
ACKNOWLEDGEMENTS
This research was undertaken with the assistance of many individuals associated with the U. S. Geological Survey and The University of
Arizona.
First of all, I would like to thank Spencer Titley and Chris
Eastoe of The University of Arizona, William Payne of Getty Mining, and
Henry Alminas of the U. S. Geological Survey for their criticisms and
assistance during the fieldwork and the preparation of this paper.
I
would especially like to thank Paul Theobald of the U. S. Geological
Survey for suggesting the topic, for his invaluable assistance and advice
in conducting the research, and for providing funding.
Additionally, I acknowledge the help of T. T. Chao and Lori
Filipek of the U. S. Geological Survey, Burt Lamoureux, and all the
other individuals who helped me in analyzing my samples.
A special thanks
must be given to E. F. Cooley of the U. S. Geological Survey for reading
my spectroscopic films.
Finally, I thank my father Richard Huston, my step- brother Larry
Green, and my friends Roy Jemison and Greg Zeihen their assistance in
collecting samples.
Without the help of all these people, the completion
of this project would have taken much longer, and the research would not
have been as complete.
iii
TABLE OF CONTENTS
Page
viii
LIST OF ILLUSTRATIONS
LIST OF TABLES
xi
LIST OF PLATES
xii
ABSTRACT
xív
INTRODUCTION, PURPOSE AND SCOPE OF THE STUDY
1
LOCATION, PHYSIOGRAPHY AND CLIMATE
4
PREVIOUS WORK
8
Geology
8
Surficial Geochemistry
9
Geophysics
10
REGIONAL GEOLOGY
11
Stratígraphy
11
Structure
17
LOCAL GEOLOGY
19
Stratígraphy
Childs Latíte
Distribution and Physiography
Petrology and Mineralogy
Batamote Andesite -- Extrusive Facies
Distribution and Physiography
Petrology and Mineralogy
Batamote Andesite- -Vent Facies
Distribution and Physiography
Petrology
Batamote Andesite -- Intrusive Facies
Distribution and Physiography
Petrology and Mineralogy
iv
19
19
19
20
22
22
22
24
24
24
27
27
27
V
TABLE OF CONTENTS -- Continued
Page
Older Alluvium
Quaternary Alluvium
28
31
Structure
Faulting
Folding
31
31
31
Alteration
32
33
LITHOGEOCHEMISTRY
Major and Minor Elements
33
Trace Elements
35
R -Mode Factor Analysis
37
STREAM SEDIMENT GEOCHEMISTRY
44
Preliminary Phase
44
Main Phase
Field Methods
Sample Preparation
Results of the Hot Nitric Acid Extraction
Results of Semi -Quantitative Emission. Spectroscopic
Analysis
Copper
Silver and Bismuth
Other Base Metals
R -Mode Factor Analysis
Results of the First Sequential Extraction
Oxalic Acid Leach
Potassium Perchlorate -Hydrochloric Acid Leach
Aqua Regia /Hydrofluoric Acid Leach
Summary
Results of the Second Sequential Extraction
The Distribution of Iron and Manganese
The Distribution of Copper in the Crystalline
Fraction
The Distribution of Copper in the Carbonate and
Exchangeable Fraction
The Distribution of Copper in the Easily Reducible
Fraction
The Distribution of Copper in the Moderately
Reducible, and Sulfide and Organic Fractions
47
47
47
48
.
.
48
50
50
53
53
59
.
61
62
63
64
64
66
68
68
68
69
vi
TABLE OF CONTENTS -- Continued
Page
Summary
Summary
69
70
Follow -Up Phase
71
Summary of the Information Derived From Stream Sediments
.
INTERPRETATIONS FROM HEAVY MINERAL CONCENTRATES
.
71
75
Field Methods
75
Sample Preparation
76
Analysis of the C -1 and C -2 Fractions
77
Spectroscopic Analysis of the CCopper
Other Elements
Mineralogy of the C -3 Fraction
tion
79
80
82
87
.
The Concentration of Copper in Pyr
ains
Summary
89
89
OTHER RESULTS
92
SUMMARY OF DATA PRESENTED, EVALUATION OF WOR
CONCLUSIONS
Evaluation of Working Hypotheses
Airborne Contamination from a Sm,
Abnormally High Background in th
Primary Mineralization
Dispersion Along Normal Faults
Contamination of the Batamote
Eruption
.
.
.
.
!YPOTHESES, AND
94
.
in Ajo
mote Andesíte
.
96
96
96
97
97
to During its
Conclusions
APPENDIX Ia: ANALYTICAL RESULTS (USING SEMI -QUANTITATIVE EMISSION
SPECTROSCOPY) FOR ROCK CHIP SAMPLES, BATAMOTE MOUNTAINS,
ARIZONA
100
l00
102
V11
TABLE OF CONTENTS -- Continued
Page
APPENDIX Ib: ANALYTICAL RESULTS (USING SEMI -QUANTITATIVE EMISSION
SPECTROSCOPY) FOR STREAM SEDIMENTS, BATAMOTE MOUNTAINS,
ARIZONA
112
APPENDIX Ic: ANALYTICAL RESULTS (USING SEMI -QUANTITATIVE EMISSION
SPECTROSCOPY) FOR THE C -3 FRACTION OF HEAVY MINERAL
CONCENTRATES, BATAMOTE MOUNTAINS, ARIZONA
128
APPENDIX Id: ANALYTICAL RESULTS (USING SEMI -QUANTITATIVE EMISSION
SPECTROSCOPY) FOR OXIDE COATINGS ALONG JOINTS AND FRACTURES,
BATAMOTE MOUNTAINS, ARIZONA
141
APPENDIX II:
ANALYTICAL TECHNIQUES
145
APPENDIX IIIa: ANALYTICAL RESULTS OF THE NITRIC ACID EXTRACTION
AND THE FIRST SEQUENTIAL EXTRACTION ON STREAM SEDIMENTS,
BATAMOTE MOUNTAINS, ARIZONA
APPENDIX IIIb: ANALYTICAL RESULTS OF THE SECOND SEQUENTIAL
EXTRACTION ON STREAM SEDIMENTS, BATAMOTE MOUNTAINS, ARIZONA
150
.
154
APPENDIX IIIc: ANALYTICAL RESULTS (USING NITRIC ACID EXTRACTION)
FOR COPPER IN THE C -1 AND C -2 FRACTIONS OF HEAVY MINERAL
CONCENTRATES, BATAMOTE MOUNTAINS, ARIZONA
159
REFERENCES
161
LIST OF ILLUSTRATIONS
Page
Figure
1.
Location of study area
6
2.
Photograph, looking east, of the high point, Batamote
Mountains
7
3.
Stratigraphy of the Ajo area
12
4.
Simplified geologic map of the Ajo and Sikort Chuapo 15- minute
quadrangles, Arizona
13
5.
Photomicrograph of Childs Latite
21
6.
Photomicrograph of the basal section of a typical flow,
Batamote Andesite
25
Photomicrograph of the upper unit of a typical flow, Batamote
Andesíte
26
Photomicrograph of the dioritic unit of the intrusive facies
of the Batamote Andesite
29
Photomicrograph of the porphyritíc unit of the intrusive
facies of the Batamote Andesite
30
7.
8.
9.
10.
11.
12.
13.
14.
Histogram showing the distribution of copper in the
Batamote Andesíte
39
Histogram showing the distribution of lead in the Batamote
Andesíte
39
Histogram showing the distribution of zinc in the Batamote
Andesíte
40
Factor loadings for 18 elements from R -Mode factor analysis
of the Batamote Andesite
42
Histogram showing the distribution of copper (extracted
using hot nitric acid) in -30 mesh stream sediments
49
viii
ix
LIST OF ILLUSTRATIONS -- Continued
Page
Figure
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
Histogram showing the distribution of silver (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
51
Histogram showing the distribution of bismuth (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
51
Histogram showing the distribution of molybdenum (analyzed
using semi -quantitative emission spectroscopy) in -30 mesh
stream sediment
54
Histogram showing the distribution of lead (analyzed using
semi- quantitative emission spectroscopy) is -30 mesh stream
sediment
54
Histogram showing the distribution of tin (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
55
Histogram showing the distribution of zinc (analyzed using
semi -quantitative emission spectroscopy) in -30 mesh stream
sediment
55
Factor loadings for 19 elements from R -Mode factor analysis
of stream sediments
57
Histogram showing the distribution of copper normalized to
iron (extracted using hot oxalic acid) in -30 mesh stream
sediments
60
Histogram showing the distribution of copper (extracted
sequentially using potassium perchlorate and hydrochloric
acid after oxalic acid) in -30 mesh stream sediments
60
Distribution of copper among mineralogic and density fractions
of selected stream sediment samples, Batamote Mountains,
Arizona
67
Distribution of copper normalized to iron (extracted using
oxalic acid) in -30 mesh stream sediment samples upstream
of sample AJ003S
72
X
LIST OF ILLUSTRATIONS -- Continued
Page
Figure
26.
27.
28.
Distribution of copper normalized to iron (extracted using
oxalic acid) in -30 mesh stream sediment samples upstream
of sample AJ039S
73
Histogram showing the distribution of copper (extracted
using hot oxalic acid) in the C -2 fraction of heavy mineral
concentrates
78
Histogram showing the distribution of copper in the
non - magnetic fraction (C -3) of heavy mineral concentrates
29.
.
81
.
83
Histogram showing the distribution of arsenic in the
non -magnetic fraction (C -3) of heavy mineral concentrates
.
83
Histogram showing the distribution of barium in the
non -magnetic fraction (C -3) of heavy mineral concentrates
.
84
Histogram showing the distribution of molybdenum in the
non -magnetic fraction (C -3) of heavy mineral concentrates
.
84
Histogram showing the distribution of lead in the
non -magnetic fraction (C -3) of heavy mineral concentrates
.
85
Histogram showing the distribution of antimony in the
non -magnetic fraction (C -3) of heavy mineral concentrates
.
85
Histogram showing the distribution of tin in the
non -magnetic fraction (C -3) of heavy mineral concentrates
.
86
.
86
Histogram showing the distribution of silver in the
non - magnetic fraction (C -3) of heavy mineral concentrates
30.
31.
32.
33.
34.
35.
36.
Histogram showing the distribution of zinc in the
non - magnetic fraction (C -3) of heavy mineral concentrates
LIST OF TABLES
Page
Table
Summary of major element oxide analyses of the Childs Latite
and the Batamote Andesite
34
Summary of emission spectroscopic analyses on the Childs
Latite and Batamote Andesite
36
Results of R -Mode principal factor analysis with iterations
after varimax rotation for the extrusive facies of the
Batamote Andesíte, Batamote Mountains, Arizona
41
Concentrations of copper in selected stream sediment samples
relative to particle size
46
5.
Replicate stream sediment sample pairs
47
6.
Results of R -Mode principal factor analysis with iterations
after varimax rotation for -30 mesh stream sediments,
Batamote Mountains, Arizona
56
7.
Samples analyzed using five -step sequential analysis
66
8.
Magnetic fractions and representative mineralogy
76
9.
Replicate heavy mineral concentrate sample pairs
80
1.
2.
3.
4.
10.
Concentrations of copper in pyrite grains from selected
heavy mineral concentrate samples
xi
90
LIST OF PLATES
Plate
1.
Sketch Geologic Map, Batamote Mountains, Arizona
2.
Rock Chip and Oxide Coating Sample Sites, Batamote Mountains, Arizona
3.
Drainage Map Showing Stream Sediment and Heavy Mineral Concentrate
Sample Sites, Batamote Mountains, Arizona
4.
Stream Sediment and Heavy Mineral Concentrate Sample Sites, Showing
Areas of Influence, Batamote Mountains, Arizona
S.
Copper, Leached Using Nitric Acid, from -30 Mesh Stream Sediment,
Batamote Mountains, Arizona
6.
Silver in -30 Mesh Stream Sediment, Batamote Mountains, Arizona
7.
Bismuth in -30 Mesh Stream Sediment, Batamote Mountains, Arizona
8.
Anomalous Molybdenum, Lead, Tin and Zinc in -30 Mesh Stream Sediment,
Batamote Mountains, Arizona
9.
Copper (Normalized to Iron), Leached Using Oxalic Acid, from -30
Mesh Stream Sediment, Batamote Mountains, Arizona
10.
Copper, Leached Using Potassium Perchlorate and Hydrochloric Acid,
Sequentially After an Oxalic Acid Leach, from -30 Mesh Stream
Sediment, Batamote Mountains, Arizona
11.
Copper, Leached Using Nitric Acid, in the C -2 Fraction of Heavy
Mineral Concentrates, Batamote Mountains, Arizona
12.
Copper in the C -3 Fraction of Heavy Mineral Concentrates, Batamote
Mountains, Arizona
13.
Anomalous Silver, Arsenic, Barium, Copper, Molybdenum, Lead,
Antimony, Tin and Zinc in the C -3 Fraction of Heavy Mineral
Concentrates, Batamote Mountains, Arizona
14.
Pyrite, Chalcopyrite, Malachite, Covellité and Arsenopyrite in the
C -3 Fraction of Heavy Mineral Concentrates, Batamote Mountains,
Arizona
xii
LIST OF PLATES -- Continued
Plate
15.
Barite, Cerussite, Galena, Lead Shot, Wulfenite and Cassiterite
in the C -3 Fraction of Heavy Mineral Concentrates, Batamote
Mountains, Arizona
ABSTRACT
To determine the cause and distribution of a widespread copper
anomaly in the Batamote Mountains discovered by the U. S. G. S. (Barton
and others, 1982), detailed stream sediment and heavy mineral concentrate
sampling and reconnaissance geologic mapping were undertaken in the area.
The stream sediments yielded two anomalous areas characterized
by copper, silver and bismuth, separated by a narrow trough of low values.
The anomalous values are spatially associated with a series of northerly
trending normal faults.
The anomalous copper is held predominantly in iron and manganese
oxides, but a significant portion is held in a reduced form (probably
organics).
Analysis of pyrite grains from heavy mineral concentrates for
copper indicates that pyrite cannot contribute enough copper to cause the
observed anomalies.
Analysis of the non -magnetic fraction of heavy mineral concen-
trates produced a similar anomaly pattern for copper, but no enhancement
was realized relative to stream sediments.
This analysis also yielded
three other anomalous areas characterized by a volatile element assemblage, a tin -molybdenum assemblage and a silver- arsenic -molybdenum assem-
blage, respectively.
The cause of these anomalies remains problematic.
The primary anomaly is best explained as the result of dispersion along normal faults.
The original source of the metals in the normal
faults could not be absolutely determined in the present study.
xiv