Petrography
Mountairs,
andageofplutonic
rocksof Florida
NewMexico-preliminary
report
byRusse//E.Clemons,NewMexico
NM
LasCruces,
State
University,
Introduction
The Florida Mountains,southeastof Deming, New Mexico (fig. l), are part of an easttilted basin-and-rangefault block. Bedrock
exposuresextend for approximately l0 mi
north-south and 5 mi east-west.Elevations
rangefrom 4,300 ft to a high of 7,448 ft on
Florida Peak.This paperpresentspartial, preliminary results of an ongoing geologic and
mineral-resources
studyof the region.
0lig6gs1s
rhyolite dikes
2
t:-l
rv
I
Eocene
v o lc on i c l o s t ic s
LJJ
Lobo Formolion
ffi
Poleozoicrocks
I
t?F]
Fr:';l S y e n fi e
T'; tt
Et..l
Gronile
.P
fT
O
FIGURE
I-INDEX
Thrust folll
R€vgrse foult
A\
Sni
MAP OF STUDY AREA IN SOUTH-
wesrNpw Msxrco.
0
Slightlymorethan half of the exposedrocks
are granitic to syenitic, locally containing
abundantmafic xenoliths.The plutonic rocks
are overlainby Paleozoicand Late Cretaceous
(?) sedimentaryrocks that underlie Eocene
volcaniclasticstrata (fig. 2). All theserocks
are cut by middleto lateTertiaryandesiticand
rhyoliticdikes.Darton (1916,l9l7) provided
the first geologicmaps of the mountains,but
some of the mineral prospectshad been describedbriefly by Lindgrenand others(1910).
Griswold (1961)provided additional knowledge about the mineralization,and Corbitt
(1971)remappedthe range.
lmi
FIGURE 2-GeNERALIzED GEor-octcunp opFLontoe MouttntNs
1980b), Brookins and Corbitt (1974), and
rocks including three kinds of granite and a
dioriteintrudedby oneof thegranites.Corbitt Brookinsand others(1978)reportedagesfor
(1971) mapped and describedthe plutonic
rocks as Precambriangranite and Mesozoic
ALS()
INTHISISSUE:
syeniteintruded by gabbro and anorthosite.
Pajaritofaultzoneof
Corbitt (1974)recognized
the possibilityof the
p.39
Espafrola
Basin
syenite,gabbro, and anorthositebeing PreNewCretaceousleaflocality
cambrianrockswhoseradiometricclockswere
in lowerKirtlandShalemember p.42
reset at some later time. He later (personal
p.46
Service/News
communication,1980)changedhis interpretaDeveloprnent of an enigrna
tion of intrusive contacts betweenthe syenite
S()()N
COMING
Darton (1916,l9l7) mappedall of the plu- and Paleozoicsedimentaryrocks to thrust1938-39earthquake
sequence
tonic rocks as Precambriangranite.Griswold fault contacts.
in MogollonMountains
(1961)recognizedfour typesof Precambrian
MeanwhileBrookins(1974a,1974b,1980a,
the plutonic rocks ranging from 371 m.y. to
1.60 b.y. Brookins (1980b)also mentioneda
quartz-monzonite-granodiorite
suite.
Brookins (1980a) and Woodward (1970)
statedthat some of the plutonic rocks are intrusiveinto Paleozoicstrata.Loring and Armstrong(1980)usedBrookins' data as supporting evidencefor Ordovician alkalic intrusives
in southwestNew Mexico, although they recognized the fact that some of the Florida
Mountains' plutonic rocks had to be pre-Late
Cambrian. Corbitt and Woodward (1970,
1973b)and Woodwardand Duchene(1981)related thrust faulting to "granitic rocks of
probableMesozoicage."
Discussion
The age and petrographyof the Florida
Mountains' plutonic rocks need clarification
in order to: l) aid mineral explorationin the
range, 2) interpret episodesof plutonism, 3)
interpret structures which cut the plutonic
rocks, and 4) understandthe basementcomposition of southwestNew Mexico. This preliminary report is basedon parts of 2 yrs of
geologicfield investigationand gatheringof
petrographic data. Field mapping is being
compiledat a scaleof l:24,000exceptin com-
^Copilol
-dome
plex areaswhere l:6,000 scaleis used.About
200 thin sectionsof plutonic rocks havebeen
examined. Approximately one-fourth of the
plutonic rock outcrops (southwestpart of
range)remainto be mapped,sampled,and examinedin detail (fig. 3). Reconnaissance
indicatesthat theseoutcropsare mostly granite
with abundantmafic xenolithsat leastin the
southern part. Zircon-apatite separatesare
being made from two syenites(central part of
range),a granite,and a diorite (southernend
of range) for U,/Pb and fission-track age
determinations.
Wide variations exist in the percentagesof
quartz and alkali feldspars,and the plutonic
rocks studied are predominantlyalkali-feldspar granites,quartz alkali-feldsparsyenites,
and alkali-feldspar syenitesaccording to the
IUGS classificationof igneousrocks (Streckeisen,1976).The predominantmineral in the
granite and syenites is perthite (fig. a).
Microcline and orthoclaseare locally common, but typicallysubordinate.All arekaolinized,and mostshowsericitization.Moderately
to stronglyundulosequartz contentrangesto
a maximum of 40t/o(table l). The feldspars
and quartz are commonly fractured, and alteration products of iron oxides, chlorite, epidote, and carbonateform fracture fillings.
The primary mafic mineral in the less-altered
alkalicrocksis predominantlyhastingsite
with
minor biotite. The majority of thin sections
examinedcontain secondaryalteration products that probably replaced the hastingsite
and biotite (table l). Zircon, apatite, and
magnetiteare common accessoryminerals.
Aplite (fine-crystalline, hastingsite alkali-
FICURE 4-PsorourcnocRApH
oF srRtNc AND
wrrH oRTHocLASE;albite ratio apBRArDeERTHTTE
proximately l:1. Q, quartz; Fe, iron oxides; width
of field 2.5 mm.
feldspar granite) dikes are common
through-
out the syeniteand quartz-syeniteoutcrops.
Thesedikesvary in width from a few inchesto
tens of feet, vary in attitude from vertical to
horizontal, and generally have gradational
contactswith the host rock. The dikesapparphasesof the
ently representlate-crystallizing
quartz-syeniticmagma.
Variationsin rock types,the wide rangein
reportedages,and the suggestionthat syenite
intruded Paleozoic strata led to the specula-
Pyromid
-^ Paol
ruxr BlissSondsfone
nonconformoble
p l u t o n i cr o c k s
tldt
-
a)
New A4exfice
GEOLOGY
. Scionco
andSeruioo
Volume
iI
1982
publishedquarterlyby
New Mexico Bureauof Minesand Mineral Resources
a divisionof New Mexico lnstituteof Mining & Tahnology
BOARD OF REGENTS
Ex Oflicio
BruceKing, Goy€raor oJ NewMexico
Leonild Delayo, Srp€rinlendenl oJ Public Instruction
Appointed
William C Abbott, 196l-1985,ItoDDs
Judy Floyd, 1977-1987,Los Cruc6
OwenLopez, 19'7-1983,SsntoFe
Dave Rice, Ssty/Tras., 1912- 1983,Carlsbod
SteveTorres,Pres., 1967-1985,Socorro
O
FIGURE 3-SKETcH MAP oF PLUToNICRocK ourcRops rN FLoRIDA MounrerNs, showing sample locations
and approximate distribution of rock types.
August1982
4, No. 3, August
New Mexico Geology
New Mexico lnstituteof Mining & Tshnology
Acling Pr$idenl
. . . CharlesR. Holmes
New Mexico Bureauof Mines& Mineral Resources
Director .. FrankE,Kottlowski
Depuly Dircctor . . .
Gmrge S. Austin
Subrriptions: Issued quilterly, Februily, May, August,
Novmber; subscriptionprice$5,00/yr.
Editorial mslter: Contributions of possible matcrial for
consideration in future issuesof NMG ile welcome.
Addrss inquiriB to Milla D. Adkins-Fleljeson,editor of
New Mqico Oeologt, Nw Mexico Bureu of Mines &
Mineral Roourco, Socorro,NM 87801
Published 6 public domain, thereJorereproducible without
permision. Sourcecredil requ$ted.
Cirelqlion: I,M
Prizl€r,' Univqsity of New Mexico Printing Plmt
tion that the plutonicrocksmay representseveral episodesof magmatism. The plutonic
rock west and immediately south of Capitol
dome(fig. 2) is alkali-feldspargranite.Alkalifeldspar granite is also the prevailing rock
south of the reversefault betweenGym and
South Peaks. Alkali-feldspar syenite and
quartz alkali-feldspar syenite, with aplite
dikes,form the outcropsin the centralpart of
the Florida Mountains. The alkali-feldspar
granite south of Capitol dome, the quartz
alkali-feldsparsyenite northwest of Florida
Peak, and the alkali-feldspargranitesouth of
oF IRoN oxIDES
FIGURE 6-PnoroutcnocRAPH
SouthPeak intrudedmeladiorite,diorite por(Fe) nrrlecluc MAFIc MINERALSANDFILLINo FRAcphyry, and diabasicrocks. Xenolithsof these
ruRES rN PERTHITE;
Q, quartz; width of field 4.5
mm.
mafic rocks locally comprise5090of the outcrop. Leucodiorite (anorthositeof Corbitt)
was also intruded by the quartz alkali-feldspar
syenitewestof Florida Peak.
alkali-feldspargranThe coarse-crystalline,
ite westof Capitol dome(figs.2 and 3) wasexposed and eroded before depositionof the
Bliss Sandstoneduring Late Cambrian time
(about510 m.y.). North of Capitol dome,a
sectionof Precambrian(?) diamictite(Corbitt
and Woodward, 1973a) was deposited on
eroded alkali-feldspar granite and then was
coveredby the Bliss Sandstone.Three wellexposedoutcrops in the central part of the
range contain depositionalcontactsof Bliss
Sandstonerestingnonconformablyon coarsecrystalline,alkali-feldsparsyenite(fig. 3). The
basalBliss Sandstoneat one outcrop is composedlargelyof well-rounded,alkali-feldspar
syenitecobblesand pebbles;thus the alkalifeldspar syenite and quartz alkali-feldspar
syenitewere uplifted and partly erodedprior
to about 510 m.y. B.P. The oldestrocks depositedon alkali-feldspargranitesouth of the
reversefault (fig. 2) are of probableLate Creassigned
taceousage.Brookins(1974b,1980a)
or calclre (Ca),
FIGURE7-PsorolatcnocRAPH
vsrr eu^lnrz(Q), eNocuelcoevnlrn(Cp)rtlltrc
agesto this graniterangingfrom 1.06to 1.60
(B) sYENlrE.
sxprcs or BnnltE oFAMERVEININ BREccIATED
2-rr,rv-wros
b.y. The meladiorite and associatedmafic FIGURE 5-Pl,q.t.t-vtrw
rcA TUNNELAND coRE, showing locations of samWidthof field2.5mm.
rockswereintrudedby this Precambriangranp l e s2 5 5 - 3 1 0 .
ite south of South Peak and similar meladiorite and leucodioritewere intruded by alkali- iron oxides; some closely resemblegossan. the breccia zonescontain carbonatemineral,
feldspar granite, quartz alkali-feldspar Locationsof thesedrill-coresitesareshownby fluorite, and barite(?);and 5) pyrite and chalsyenite,and alkali-feldsparsyenitewest and FM-l throughFM-8 symbols(FM-6 doesnot copyrite ioat someof the fracture surfacesas
exist) on fig. 3. The alkali-feldsparsyenites well as being presentin some brecciaveins
northwestof Florida Peak.
Alteration of the plutonic and overlying beneathhorizontalor nearlyhorizontalaplite (fig. 7).
Low-grademineralizationis widespreadin
conglomeraticor volcaniclasticrocks is wide- dikesaremuchmorealteredthan the aplitesor
of alkali-feldsparsyenitesabovethe aplites. This the Florida and Little Florida Mountains.Exspreadand pervasive.The entire sequence
more than 1,600ft of Eocenevolcaniclastic greateralteration may be a result of damming act mineral productionfiguresare unknown,
rocks (fig. 2) north of Florida Peak has been of ascendinghydrothermalfluids beneaththe but the ores containedmanganese,fluorspar,
barite, zinc, lead, silver, copper, and gold.
intenselypropylitized.Epidoteconcretionsup lessporousaplites.
The lead, zinc, and silver oresoccur mainly in
a775excavated
Barite
America
recently
of
locally
in
diameter
are
abundant
12
inches
to
Paleozoiccarbonaterocks. A vein of galena,
of
in the Eocenesectionas, for example,beneath ft tunnel approximately I mi southeast
Florida Peak. Thin sectionsshow that the Florida Peak in an exploratory attempt to fluorite, barite, calcite, and quartz was mined
sandstonesare chiefly plagioclasereplacedby transecta barite vein. A horizontal,900-ft,2- in the Lobo Formationand in syenitelessthan
epidote, carbonate, and clay minerals(?). inch-diametercore was taken from the end of I mi south of Florida Peak. Oxidized copper
Joints and fractures in the Lobo Formation the tunnel (fig. 5). Thin-sectionand hand- minerals are present in the meladiorite and
southof Florida Peakarealsocoatedwith epi- specimenstudy of alkali-feldspar syeniteand syeniteabout I mi southeastof Capitol dome.
dote and other secondaryminerals.The vast quartz alkali-feldspar syenite core samples Lead, copper, and zinc(?)prospectshavebeen
majority of plutonic rocks in the centralpart (fig. 5 and table l: samples255-310)revealed describedby Griswold (1961)in the Eocene
fluorite, and
rocks.Manganese,
of the range, from one flank to the other, are that: l) approximately half of the core con- volcaniclastic
sheared and contain abundant iron oxides sisted of intensely brecciated and altered barite veins were deposited in fanglomerate
(mostly limonite). Six of the sevendrill cores rocks; 2) only three samplescontainedrecog- derived from 23.6-m.y.-old rhyolite in the
taken by Brookins and others (1978) and nizable hastingsite-the rest have chlorite, Little Florida Mountains.
stored at the New Mexico Bureau of Mines epidote, and carbonate replacing hastingConclusions
and Mineral Resources contain intensely site(?);3) microscopicas well as megascopic
consisting of contact relaevidence,
Field
(fig.
many
of
4)
6);
sheared,brecciated,alteredrocks stainedwith brecciazonesareabundant
New Mexico Geology
August 1982
tions with overlying Precambrian(?) and Late
Cambrian strata, gradational lithologies
within the alkalic plutonic rocks, and intrusive
contacts between these and older mafic rocks.
indicate that all of the Florida Mountains' plutonic rocks are of Precambrian age. The probable cause of the spurious radiometric dates is
alteration related to middle to late Tertiary
volcanism and mineralization. Field and petrographic data show intense hydrothermal
alteration of most of the plutonic rocks and of
other rocks as young as the late(?) Eocene
volcaniclastic strata. This study has provided
information supporting the following chronologic sequenceof events in the Florida Mountains.
The oldest plutonic rocks in the Florida
Mountains are a complex of meladiorite, leucodiorite, and diabase(?).These rocks were intruded during Precambrian time by an alkalic
magma from which alkali-feldspar granite,
quartz alkali-feldspar syenite, and alkalifeldspar syenite crystallized by partial differentiation. Overlying country rock was removed and the pluton partly eroded prior to
Late Cambrian time and probably before close
of Precambrian. The pluton was then covered
by about 3,700 ft of Paleozoic sedimentary
rocks. Uplift at the close of the Paleozoic and/
or during early Mesozoic time and subsequent
erosion removed much of the cover from the
plutonic rocks once again. The Lobo Formation of probable Late Cretaceousor early Tertiary age was deposited on the eroded Precambrian rocks west and south of Florida Peak
and at the southeastend of the range. Following deposition of a thick volcaniclastic blanket
during middle to late(?) Eocene time, rhyolitic
and andesitic dikes were emplaced, probably
during the Oligocene or early Miocene.
Hydrothermal fluids from underlying magmas, associated with or contemporaneous
with early Miocene volcanism in the Little
Florida Mountains, produced extensivealteration of the plutonic rocks and mineralization.
AcKNoWLEDGMENTS-The New Mexico
Bureau of Mines and Mineral Resources.F. E.
Kottlowski, Director, provided financial support for the fieldwork and thin-section preparation. Hospitality of area ranchers and claim
owners provided easy accessto the range. Discussionswith G. Brown, C. E. Chapin, L. L.
Corbitt, R. E. Denison, F. E. Kottlowski, G.
Mack, W. R. Seager, and S. Thompson III
during the investigation provided ideas and
aided in formulating the interpretations presented here. L. Horton and Barite of America
kindly provided access to their exploration
tunnel and donated samples of the core for
study. W. R. Seager also read the original
manuscript and made several suggestions for
its improvement. I extend my sincere thanks
and appreciation for all this aid. An earlier
version of this paper was presentedat the 1982
annual meeting of The Metallurgical SocietyAIME in Dallas, Texas. Publication of this revised, expanded paper is with their permissl0n.
References
Brookins, D. C.,l9'74a, Preliminary radiometric age determinations from the Florida Mountains. New Mexico: El
Paso Geological Society, Guidebook 8, p. 47-56
36
August1982
New Mexico Geology
-,
1974b, Radiometric age determinations from the
Florida Mountains, New Mexico: Geology, v. 2, p. 55555'7
-,
1980a, Geochronologic evidence for Paleozoic plutonic activity in Florida Mountains, New Mexico (abs.):
American Association of Petroleum Geologists, Bull , v.
64, no. 5, p 681-682
-,
1980b, Paleozoic plutonism from southern New
Mexico-Evidence from the Florida Mountains: Geophysical ResearchLetters, v. 7, no. 10, p 141-744
Brookins, D G., and Corbiil, L. L., 1974, Preliminary RbSr study of igneous rocks of the Florida Mountains, New
Mexico: EOS (American Geophysical Union, Transact i o n s ) ,v 5 5 , n o . 4 , p . 4 7 0 - 4 7 1
Brookins,D.G.,Rautman,C.E,andCorbitt,L L,1978,
A study of silicic plutonic rocks in the Zuni and Florida
Mountains to evaluate the possible occurrence of disseminated uranium and thorium deposits: Albuquerque, New
Mexico Energy Institute, Rept. No. 77-l 104C, 22 p.
Corbitt,L.L.,l9Tl,StructureandstratigraphyoftheFlorida Mountains, New Mexico: Ph D. thesis, University of
New Mexico, I 15 p.
-,
1914, Structure and stratigraphy of the Florida
Mountains: El Paso Geological Society, Guidebook 8, p.
l6-29
Corbitt, L. L., and Woodward, L A., 1970, Thrust faults
of the Florida Mountains, New Mexico, and their regional tectonic significance: New Mexico Geological
Society, Guidebook 2lst field conference, p 69-74
-,
1973a, Upper Precambrian diamictite of Florida
Mountains, southwestern New Mexico: Geological Society of America, Bull , v. 84, no. l, p. l7l-173
1973b. Tectonic framework of Cordilleran foldbelt in southwestern New Mexico: American Association
o f P e t r o l e u m G e o l o g i s t s ,B u l l . , v . 5 7 , n o . l l , p . 2 , 2 0 7 2,216
Darton, N. H., 1916, Geology and underground water of
Luna County, New Mexico: U.S Geological Survey,
B u l l . 6 1 8 , 1 8 8p .
-,
19'17, Geologic atlas of the U S., Deming folio:
U.S. Geological Survey, Folio 207
Griswold, G B., 1961, Mineral deposits of Luna County,
New Mexico: New Mexico Bureau of Mines and Mineral
Resources,Bull. 72, 157 p.
L i n d g r e n ,W , c r a t o n , L . C . , a n d G o r d o n , C . H . , 1 9 1 0 ,
The ore deposits of New Mexico: U.S. Geological Survey, Prof Paper 68, p 289-290
Loring, A. K., and Armstrong, D G , 1980, Cambrian-Ordovician syenitesof New Mexico, part of a regional alkalicintrusiveepisode:Geology,v 8,p.344-348
Streckeisen, A., 1976, To each plutonic rock its proper
name: Earth-ScienceReviews, v. 12, p. l-33
Woodward, L A., 1970, Precambrian rocks of southwestern New Mexico: New Mexico Geological Society, Guidebook 2lst field conference, p. 27-31
Woodward, L. A., and Duchene, H. R., 1981, Overthrust
belt of southwestern New Mexico-comparison
with
Wyoming-Utah overthrust belt: American Association
of Petroleum Ceologists, Bull., v 65, p 722-729
-.
TABLE l-Mooer- eNeLyspsop FLonroe Mourrerus'pLUToNrc RocKs(Kf, alkali feldspars; Qz, quartz; Pl,
plagioclase An > 5; Bi, biotite; Am, amphibole; Px, pyroxene; Al, chlorite, epidote, iron oxides, carbonates; and Ac, apatite, zircon, magnetite).
Sample No.
Kf
27
76
28
29
58
36
61
42
51875
5q
60
or
62
64
65
67
68
69
70764
71
72
q)
Qz
PI
Bi
43
1
1
Am
Px
18
15
33
52
'l
)T
30
73
79
lI
72
70
4
8
26
19
26
1I
66
22
24
2
I
tr
48
814
3
23
19
7
4
6
2I
7
2
6
4
I7
AI
4
1
3
3
2
7
1
4
1
I
53
35
22
15
13
zo
6
10
cr
q
I
tr
1
3
cr
cr
1
ET
Quartz Syenite
Di.abase
Quartz Syenite
Granite
Diorite
QuarEz Syenite
Syenite
Diori Le
Diorite
Meladiori.te
Quartz Syenite
Aplite
A pl i t e
ApliEe
Granite
Granite
(continueO
publication
Newbibliography
introduced
The New MexicoBureauof Minesand MinThe New MexicoBureauof Minesand Mineral Resources
hasissueda newpublicationin eral Resources
will continueto issuea GeoRef
cooperationwith the AmericanGeologicalIn- bibliographyon an annualbasis.Betweenedistituteand GeoRefInformation System,Blb- tions the Bureau will work with GeoRef to
liography and index of New Mexico geology. makecorrectionsand find omissions.Usersof
This edition, containing approximately750 thebibliographyareencouraged
to contactthe
references,representspublishedand unpub- Bureaueditingstaff whenerrorsor omissions
lishedmaterialthat was addedto the GeoRef are discoveredand to commentcritically on
databasein 1981.The componentsof this an- the volume'sscopeand format. Coverageof
nual bibliographyfor New Mexico are: serials the literature will becomeincreasinglymore
list, citationsby author with crossreferences, comprehensive
with eachsuccessive
editionas
subjectindex,countyindex, and rock-unit in- Bureau and user participation in the datadex.
processcontinuesto grow.
base-building
Many publicationsreleasedin l98l are inThe annualGeoRefbibliographyis a timely
cluded,but this volumeis not a comprehensive supplement to the Bureau's bibliographic
annual bibliographyand containsadditional literaturebringingmore recentpublicationsin
citations for papers and reports releasedin geoscienceto researchers.The bibliography
earlieryears.The Bureaudid not participatein sellsfor $5.00and is availablefrom the Publicollecting or in formating the referencesfor cations Office, New Mexico Bureau of Mines
this volume; therefore,many citations may and Mineral Resources,
Socorro,New Mexico
duplicate those appearing in earlier Bureau 8 7 8 0 1 .
bibliographiesor its forthcoming bibliography
(Bull. 109).
-Jane Calvert
for 1976-1980
Florida MountainsTABLE | (continuedl
Srmple No.
76
77
78
7q
81
82
83
84
85
86
87
89
90
91
92
93
94
95
96
97
98
99
100
101
205
208
220
22I
223
224
225
LLO
227
228
229
230
ZJI
232
L))
234
236
253
255
256
251
258
?5q
260
26r
262
263
265
266
267
268
269
270
27L
272
273
274
275
276
277
278
279
280
28r
282
283
284
285
286
287
Kf
854
70
74
80
74
80
76
66
65
63
76
61
61
61
minerals
NewMexico's
Qz
62
24
3
1
2
tr
15
19
23
28
16
31
30
26
tr
30
64
28
PI
Bi
L)
tl
z3
l8
9
15
LZ
9
8
3
I
ot
42
54
.L)
t)
l.4
8
I
tr
tr
2
65
3
II
8
L4
6
4
9
l2
25
9
2
24
3
34
4r
43526
6L
30
62
30
254
24
44
32
28
37 31
2r
69
44
23
65
24
58
866
65
28
83
17
16
73
845
848
855
864
862
855
88
1
838
78 15
84
11
848
1
19
834
75
15
82
11
83
t0
864
1
90
13
78
7L6
834
80
10
856
834
684
76
4
872
882
799
828
2
L]
5
46
7
46
7
z6
31
2r
30
II
Al
Px
10
6
49
68
63
9L1
61
9)62
50
Am
L2
14
tr
tr
10
50
5
l
4
l5
2
tr
2
12
18
3
tr
11
11
3
9
10
11
10
11
9
7
5
8
T4
13
10
7
l
10
9
9
23
13
10
9
L2
2l
19
11
r4
10
10
11
9
I
Er
tr
2
1
2
tT
fr
tr
tr
cr
tr
tr
2
6
tr
4
I
5
8
2
tr
tr
ET
1
tr
tr
cr
ET
I
tr
6
3
tr
2
tr
4
tr
tr
tr
tr
tr
cr
1
1
II
1
TI
tr
tr
f 7
tr
tr
cr
tr
tr
tr
tr
tr
EI
tr
cr
tr
tr
I
1
I
tr
Er
I
1
CI
Syenite
A pI i t e
Syeni te
SyeniEe
Syenite
Syenite
QuarEz Syenite
Quartz Syenite
Granite
GraniEe
Quartz SyeniEe
Granite
Aplite
GraniLe
Melad iorite
Granite
Meladiorite
Apli te
Diori te
Meladiorite
Dior ite
Granite
Granite
Syenite
Grani te
Syeni te
Granite
Granite
Granite
Quartz MonzoniEe
Granite
Granite
Diori Ee
A pl i t e
Aplite
Granite
Meladiori te
Grani te
Granlte
Quartz Syenite
Granite
Quartz Syenite
Quartz Syenlte
Quartz Syenite
Quartz Syenite
Quartz Syenite
Syenite
Syenit e
Quartz Syenite
Syenite
Quartz Syenite
QuarEz Syenite
Quartz Syenite
Quartz Syenite
Quartz Syenite
Syenite
Quartz Syenite
Quartz Syenite
Quartz Syenite
Syenite
Syenite
Quartz Syenite
Quartz Syenite
Syenite
Quartz Syenite
Quartz Syenite
Syenite
Syenite
Syenite
Syenite
Quartz Syenite
Quartz Syenite
Syenite
Quartz Syenite
Quartz Syenite
PhotobyK S Ridel
CALCITE, CACO.. LORDSBURC MINING DIS.
TRIcT, HIDALGO COUNTY, NEW MEXICO
Crystal system: hexagonal (rhombohedral)
Hardness:3
Cleavaee:(t0Tt),
Specificgravity:2.71
perlect
Color: colorless to white; can be tinted various
colors by impurities. Specimen pictured has a
very light pink tint, probably becauseof iron
or manganeseimpurities.
S p e c i m e np i c t u r e d : 3 % i n c h e s w i d e , 3 % i n c h e s
rall
Calcite is a common rock-forming mineral
and is the principal constituent of limestone,
chalk, and marble. Also a common cave deposit, calcite forms stalactites and stalagmites.
Calcite is a common gangue mineral formed in
many hydrothermal ore deposits, such as those
of the Lordsburg district. The name calcite
comes from the Latin "calx" which means
burnt Iime
-Robert M North
in
activity
Seismic
Mexico
centralNew
Three minor earthquakes were felt
at Socorro in May of this year: two
on the l8th at12:.00a.m. (MDT) and
12:09 a.m. (MDT) and one on the
24th at 1232 a.m. (MDT). These
shocks,with magnitudesof 2.6,2.6,
and 2.7, respectively, had dePths
near 1l km and epicenters near 34o
4.4' N. and 106" 51.6' W. Because
the epicenters were only 2 mi northeast of Socorro, the shocks were felt
by a large number of people in and
near the town. The felt shocks were
the strongest eventsin an earthquake
swarm that commenced on MaY 8th
and as of June 3rd had produced
over 200 recorded shocks at Socorro
from the same general hypocentral
reglon.
-Allan
Sanford and LarrY Jaksha
(continueA
New Mexico Geology
August 1982
Florida MountainsTABLE | (concluded)
Srmple No.
Kf
288
84
289
88
290
69
29r
81
292
85
293
68
294
81
295
88
296
58
297
82
298
82
299
79
300
92
301
83
302
83
303
84
304
86
305
84
306
87
307
83
308
86
309
85
3r0
84
320
32L
48
Fr'11-3
67
10
56
t9
67
28
67
32
68
38
59
41
66
46
74
ET12-2
59
86028
11
63
rt
50
21
58
29
49
31
56
36
70
37
68
38
52
Eyr4- 2
83
9802
11931
16901
20861
11'15-3
68
88018rr
14
75
16
67
zz
of
3065223
Fy7- 4
85
11853
25873
32724
41
79
47
67
53
69
FM8- 1
77
88118
10809
Qz
Bi
Pl
5
1
19
3
2
12
2
2
13
2
5
9
3
8
2
6
2
s
3
4
2
2
2
33
26
20
16
23
18
26
25
2r
26
Px
AI
o
3
5
o
10
8
8
1
tr
tr
4
18
t6
10
L6
t2
11
5
8
15
9
11
10
8
13
t2
1?
13
2
2
7
24
t7
10
45
16
I5
8
5
15
tt
9
6
2
3
I
1
2
7
I2
4
6
5
2
ET
I
I
1
b
z6
28
43
25
43
29
20
24
4r
2
29
Am
z
I
I
tr
I
1
tr
1
Er
tr
z6
Er
2
14
16
I
15
I
1
I
2
tr
tr
cr
1
o
I
tr
tr
tr
ET
tr
tr
1
ET
cr
1
ET
I
tr
8
t5
10
8
6
4
tr
tr
tr
ET
I
2
3
1
I
I
1
Quartz Syenite
QuarEz SyeniEe
Quartz Syenite
Syenite
Quartz Syenite
Quartz Syenite
Syenite
QuarEz Syenite
SyeniEe
Syenite
Syenite
Meladiori Ee
Granite
Granite
Granit e
Quartz Syenite
GraniLe
QuarEz Syenite
Granite
Granite
Granite
Grani te
Granite
Granite
Granite
Granite
Granite
Granite
GraniEe
Granite
Granite
Syenite
Syenite
Syenite
Photo by Glenn R Osburn
Columnar jointing in La Jencia (Vicks Peak) Tuff
in Cold Springs Canyon, eastern San Mateo Mountains, Socorro County, New Mexico. These joints
average approximately I ft apart. This unit is a
densely welded ash-flow tuff of regional extent that
was erupted from the Nogal Canyon cauldron in the
southeast San Mateo Mountains. In Cold Springs
Canyon, near the cauldron, the tuff is approximately 800 ft thick. The view is toward the north;
Cold Springs Canyon runs from lower right to middle left in the photo separating the areas of shallowing dipping joints in the foreground from the vertically jointed area in the background. In volcanic
rocks, columnar joints form by contraction during
cooling. These joints are typically vertical, perpendicular to the upper and lower cooling surfaces of
the unit. The nearly horizontal joints in the foreground probably formed near a cliff or valley wall
that was buried by the tuff. A more comprehensive
treatment of the geology of this area has recently
been prepared by Glenn Atwood (M.S. thesis, University of New Mexico, 1982).
-Glenn R Osburn
1
I
q
6
Quartz Syenite
Syenite
ET
rr
22
28
Gallery
of Geology
ET
11
2
3
5
7
10
13
T2
10
23
6
t7
29
Quartz Syenite
Syenite
Quartz Syenite
Syenite
ET
tr
tr
cr
tr
Granite
Quartz Syenite
Granite
GraniEe
Granite
Granite
ET
ET
tr
1
1
ET
I
tr
!r
1
Syenite
Quartz Syenite
QuarLz Syenite
Syenite
Quartz Syenite
Quartz Syenite
Quartz Syenite
tr
Announcement-Call
forpapers
The 3rd biennial New Mexico Minerals Symposium will be held Saturday and
Sunday, November 13 and 14, 1982, at the Macey Conference Center on the
campus of the New Mexico Institute of Mining and Technology in Socorro. The
purpose of the New Mexico Minerals Symposium is to bring together for an ex_
change of items both professionalsand amateurs interestedin the mineralogy of
the state. The symposium provides both groups a forum to presenttheir cumula_
tive knowledge of mineral occurrencesin New Mexico. In addition to the formal
38
August 1982
NewMexico Geology
papers,informal discussions
among mineralogists,geologists,and hobbyists
shouldbenefitall.
Personswishingto givepapersat the symposiumareaskedto submitabstracts
by October15,1982.More informationmay be obtainedfrom:
RobertM. North, Mineralogist
N.M. Bureauof Mines
Socorro,NM 87801
505/835-5246