UDH Report Chapter
The Magma-Metal Series Classification
Foundational to the UDH Model
The UDH model grew out of the Magma-Metal Series Chemical Classification of Igneous Rocks and
Mineral Deposits. The development and testing of this classification began in the 1970’s. Since the
early 1980’s development and testing of the classification has been done by MagmaChem
Exploration, Inc. This classification provides the empirical basis and logical framework for the UDH
model. The MagmaChem Classification was originally applied to mineral exploration, leading to the
discovery of 21 metal deposits on 3 continents, and has been used as a predictive tool to help
unravel the complex geology of regions such as the western United States.
This chapter is an historical overview and generalized description of the MagmaChem Classification,
how it contributed to the mineral deposit discoveries and led to the development of the UDH
model. The overview is written chronologically and divided into four decades (Figure 1). The
history of the work leading up to the UDH model provides the empirical and conceptual basis
required for truly understanding the model and for effectively applying it to petroleum exploration.
It is important to note that it also illustrates the great diversity of data types and the integration of
multiple geoscience disciplines that were required to develop the UDH model. For a more detailed
description of the MagmaChem Classification and history of its development (see Appendices 1-4).
Figure 1: Historical timeline of the MagmaChem Classification and the UDH model
MagmaChem is not the first to attempt to empirically link mineral deposits to magmatism and
geotectonic setting. However, MagmaChem’s work constitutes a more specific, logically organized
empirical proof that builds on many earlier, more qualitative observations and classification. The
earliest description relating magma and mineral deposits was made by Decartes in 1644. He
considered that most mineral deposits were epigenetic in character and constituted addition of
metallic elements into a chilled upper crust from a still hot interior sub-crust. Hutton’s classic work
“Theory of the Earth” in 1788 was much more specific. In 1847, de Beaumont published a
comprehensive treatise entitled “Note sur les emanations volcaniqes et metalliferes.” The next major
statement supporting magmatism as a source for ore deposits came with the publication of “The
Genesis of Ore Deposits” by Posepny in 1894. J.E. Spurr in 1903 took Posepny’s speculations a
major step further in his paper entitled “A Consideration of Igneous Rocks and Their Segregation or
Differentiation as Related to the Occurrence of Ores.”
This early work set the stage for Waldemar Lindgren--one of the most outstanding students of ore
deposits of all time. At the end of his life Lindgren was conceptually far beyond his famous
thermodynamically-based classification and was in the process of linking the compositional
parameter of his thermodynamic classification to the chemistry of closely associated magma series to
mineral deposits. If Lindgren had lived another decade or if M.A. Peacock had published his
alkalinity classification of igneous rocks titled “Classification of Igneous Rock Series” ten years
earlier in 1921, the framework of a comprehensive, specific and predictive classification for mineral
deposits and their associated magma series might have emerged much earlier and the MagmaChem
Classification would have been unnecessary. Not only did Lindgren make fundamental linkages in
1933 between igneous rocks and mineral deposits, be conjoined them with what we now call
subduction in plate tectonic parlance. The following words were written by Lindgren and published
posthumously in 1933 thirty years before the plate tectonic revolution:
“It is held that the whole Cordilleran metallization is based on the gradual eastward
movement of deep-seated magma beginning with the original impulse from the
Pacific. That impulse is no doubt caused by the reaction between the North
American continent and the deep sima layers of the Pacific, but this question had
better be left to the geophysicists.”
After Lindgren died in, his successors especially L.C. Graton and R. H. Sales from 1933 to 1968
refined his earlier thermodynamic classification. Their work now shares the spotlight with structural
classifications based on ore deposit form by Buddington, 1935; Bateman, 1942; Newhouse, 1942;
Park and MacDiarmid, 1964. The advent of the plate tectonic paradigm in the late 1960’s turned the
attention of ore deposit thinking away from the classical Lindgren approach toward the linkage
between geotectonic setting and mineral deposit phenomena. Important contributors include:
Guilbert, 1981; and Guilbert and Park, 1986, and finally linking geotectonics, magmatism and
mineral deposits or some variation on this theme; I. Baragar, 1971; Hutchinson, 1973; Naldrett
and Cabri, 1976; Jensen, 1976; Fox, 1979; Naldrett, 1981; Westra and Keith, 1981; Guilbert,
1981; Mitchell and Garson, 1981; Hutchinson, 1982; and Guilbert and Park, 1986.
In the 1970 several events set the stage for the development of the Magma-Metal Series
classification. These included: the new paradigm of plate tectonics, the proliferation of multielements and whole rock geochemistry, a growing data base of isotopic age dates, and the fact that
no one had followed up on Lindgren’s prophetic words concerning the relationship between
magmas and mineral deposits and plate tectonics.
1970-1980 Pre-MagmaChem and Discovery of Magma-Metal Series
Project topics listed by year:
38 publications, 6 unpublished works
1970
1971
1972
1973
1975
1977
1978
1979
Geologic mapping, Arizona
Geologic mapping, Arizona
Mineralogical studies
Recumbent folds
Basement kinematic analysis, Arizona
Precambrian orogeny, NA
Regional geotectonic analysis, southwestern US
Radiometric age date compilation, Arizona
Devonian tectonism, Arizona
Basement structure and magmatism
Metamorphic core complex discovery, western US
Copper production in, Arizona
Porphyry Cu genesis, southwestern US
Paleosubduction and magmatism, NA
Geologic road logs, Arizona
Subduction to transform tectonics, southwestern NA
Arizona overthrust oil play
Subduction, magmatism, metallogeny, southwestern NA
Jurassic-Triassic sedimentation/paleotectonics, Arizona
Geologic quad maps, Arizona
The beginnings of the UDH model can be traced back to the 1970s’ when Stan Keith, who would
later co-found MagmaChem, was mapping the geology of several Arizona porphyry copper deposits
and recognized a relationship between Laramide-age igneous stratigraphy and the metal content of
associated mineralization. In the field he observed, mineralogically, that older more potassic-rich
igneous rocks were associated with Pb-Zn-Ag mineralization and that younger less potassic-rich
rocks were associated with Cu-Mo mineralization. To chemically confirm this observation he
collected samples of the igneous rocks for whole rock analysis and samples of the associated
mineralization for multi-element analysis. He then plotted the data on a K2O-SiO2 variation diagram
to graphically quantify the relationship. The plots confirmed his mapping and mineralogical
observations (Figure 2).
Figure 2: K2O versus SiO2 variation diagram for plutonic data associated with various base metal
metallogeny in southeastern Arizona
To test this igneous rock metallogenic correlation over a broader area, Keith obtained data for the
entire western US and northern Mexico for Cretaceous through Cenozoic magmatic systems and
associated mineralization. The result was that the correlation recognized in the field and in the
chemistry of the Arizona igneous rocks and mineralization continued to hold up. The variation
diagram K2O versus SiO2 for plutonic data associated with metallogeny in the western US and
northern Mexico confirmed that plutons associated with Pb-Zn-Ag metallogeny consistently plot
more potassic at a given silica content than plutons associated with porphyry Cu-Mo metallogeny.
The differences in potassium content were of a serial character; that is, the igneous suite of rocks
associated with Pb-Zn-Ag deposits had consistently higher potassium contents compared to igneous
rocks associated with Cu-Mo deposits, and comprised a mafic through silicic differentiation
sequence. This discovery of the serial nature of igneous suites and their associated metallogeny,
referred to as “Magma-Metal Series” and first seen in Arizona, became the core concept of the
MagmaChem Classification and the fundamental paradigmatic parameter around which it revolves.
In a sense, mineral deposits are simply the products of “dirty magma”--the dregs left over at various
stages during differentiation of a particular magma series. It follows that these left-over metals may
be used to referee the chemical classification of a magma series based on the magma series’ own
major and trace element content.
In the early 1970’s Monte Swan, who would later co-found MagmaChem with Stan Keith, met him
at the University of Arizona and began following the conceptual development of the Magma-Metal
Series idea and Keith’s field work. He was particularly interested in applying Stan’s work to his
basement structural work for Kennecott’s Geologic Research Group, which was focused on the
structural control of the emplacement of porphyry Cu deposits. He was attempting to relate
magmatism and the mineralizing fluids to the kinematic history of basement structures. When he
met Keith, he was just completing a five year field-based study of the basement structural of Arizona
and New Mexico, the infamous Texas Zone (which in later work became a “Crack of the World”)
and a kinematic analysis of a Precambrian shear zone. The results of this research was presented and
published by Swan in the late 1970’s. Most importantly it expanded and stimulated Keith’s thinking
regarding the basement structural control of magma emplacement and migration of mineralizing
fluids and the value of kinematic analysis.
The field observation by Keith that led to the discovery and development of the Magma-Metal
Series concept also led to a formal igneous rock and mineral deposit classification, and a layered
Earth model. In combination with Swan’s structural work and the work of many other colleagues, it
led to the development of new exploration tools, the discovery of 21 mineral deposits on three
continents totally $65 billion in metal value and finally the development of the UDH model. This
connection, to a field observation by Keith, makes the point that the UDH model is ultimately about
geology. But it’s also about collaboration with many individuals and companies to the point of
MagmaChem becoming a virtual “clearing house” for industry geologic data and ideas. This
philosophy of openness with both ideas and data was a key to the success of MagmaChem.
Complete documentation of the people, companies and institutions that have contributed to the
Magma-Series Classification and the UDH model can be found in various Appendices.
Beginning in 1978, more than 160 papers have been presented and published, 200 company reports
written, and 11 theses sponsored on various subjects related to the MagmaChem Classification. The
first Magma-Metal Series publication was written by Keith and published in Geology magazine by the
Geological Society of America in 1978. It is entitled, “Paleosubduction Geometries Inferred from
Cretaceous and Tertiary Magmatic Patterns in Southwestern North America.” Keith’s paper links
subduction to continental geology using a preliminary version of Magma-Metal Series and isotopic
age dates and demonstrated how the new paradigm of plate tectonics had the potential to integrate
oceanic and continental data in a predictive way. In this paper Keith adapted M.A. Peacock’s (1931)
fourfold chemical classification of igneous rocks based on the alkali-lime index, i.e. calcic, calcalkalic, H-K calc-alkalic, alkali-calcic, and alkalic. This nomenclature was later officially adapted into
the MagmaChem Classification. In the paper Keith used these alkalinity types to describe the
composition of melts generated at various melting depths along the subducting oceanic slab.
1980-1990 The Earth’s Mantle and Founding of MagmaChem
1 Au deposit discovery:
Trout Creek (Valmy), Nevada 1988 179,000 ounces Au
62 publications and 90 unpublished works
MagmaChem project topics listed by year:
1980
1981
1982
1983
1984
1985
1986
Molybdenum mineral associations, Arizona
Uranium and western US metamorphic core complexes
Stacked thrust faults west-central, Arizona
Intrusion/deformation, western US metamorphic core complexes
Molybdenum classification and genesis
Greenstone gold exploration, central Arizona
Peraluminous magmatism and low-angle subduction, southwestern US
Sedimentational-tectonic patterns of Sonora and Arizona
Plate tectonics and mineral deposits, northern Mexico
Exhalative gold exploration model
Peraluminous igneous rock classification
Mineral district compilation Basin and Range
SW-directed thrusting in metamorphic core complexes, Arizona
Magma-Metal Series Classification and geotectonic setting
Sevier-Laramide paleo-tectonic petroleum maps, western US
Gold exploration models, Mojave region
Early Jurassic stratigraphy/paleogeography southeastern, Arizona
Magma-Metal Series and greenstone gold metallogeny
Western Washington mineral system assessment
K-Ar age date compilation Arizona
Field trip guidebooks: low-angle tectonics of Arizona
Strato-tectonic analysis, southwestern US
Cordilleran decretion, western US
Late Cenozoic igneous rocks, geotectonics, metallogeny of Arizona
Borate deposits and Magma-Metal Series, western US
Precambrian 1.4 b.y. orogeny
1987
1988
1989
Oxidation fugacity control of base metals and gold, Arizona
Strato-tectonic analysis of the Idaho Batholith
Laramide magmatism, tectonics, metallogeny, southwestern US
Magma-Metal Series and Geotectonics (1000 page manuscript)
Peraluminous Au deposits classification
Paleo-tectonic strato-tectonic petroleum analysis, Columbia
MagmaChem Handbook of Geochemical Models (300 page manuscript)
Volcanogenic massive sulfides, Colorado
MagmaChem “call” decision tree
Magma-Metal Series applied to Nevada gold
Distribution of metals in modal mineralogy
Strato-tectonic section thermal petroleum history, Colorado
Strato-tectonic section, California, Arizona, New Mexico
Western US oxidation state map
Geochemical zoning of Nevada gold systems
Continued work in the 1980’s on the Magma-Metal Series concept, by Keith and Swan,
MagmaChem employees and associates, focused on the Earth’s mantle resulting in the development
of:
1. The Magma-Metal Series Classification
2. An 8-layered mantle model
3. The technique of strato-tectonic analysis
4. Crustal oxidation state concept
This work was funded primarily by the mineral industry, although the petroleum industry and the
USGS provided funds. Keith and Swan co-founded MagmaChem Exploration, Inc as the research
and business vehicle for this work. The bulk of the work focused on data compilation that
continued throughout the 1980’s and included global “hard” (empirical) igneous rock and mineral
deposit data gathered from all published sources (primary and gray literature) and augmented by a
large volume of unpublished data generated by MagmaChem’s clients. The data types included:
geochemistry, mineralogy, isotopic age dates, stratigraphy, geologic field relationships and especially
geologic maps. From this data Magma-Metal Series relationship were tested and refined. As a result
thousands of mineral systems were geographically and geologically defined. This includes data from
more than 12,000 mineral systems. (In 1986, the USGS consider adopting this approach to their
mineral data base). Many compilation products were provided for the mineral and petroleum
industries. The philosophy behind this massive undertaking was inductive in nature i.e. empirical
data was assembled from scratch revealing natural patterns. Through these patterns, among many
other discoveries and developments, crustal magma and metal sources were identified, plate
tectonics was linked to continental geology and mineral deposits, the slab segmentation of
subducting oceanic lithosphere was recognized, crustal oxidation state maps were created, and
Expert System software was written. These are only a few of a long list of discoveries, exploration
tools and products that are described in detail in the Appendices. Most importantly, of interest in
this report, they were applied to mineral and petroleum and lowered exploration risk, often
dramatically.
In the early 1980’s the notion of Magma-Metal Series was expanded beyond the calc-alkalic/alkalicalcic serial distinction through several projects and publications. By the 2000’s, 194 Magma-Metal
Series had been defined and 442 rock systems, of which 91 are economically favorable and the
definition of Magma-Metal Series was expanded to:
A co-genetic sequence of igneous rocks and metal deposits linked by a process of
fractional differentiation along a petrochemically-distinct mafic to felsic path of liquid
descent from and controlled by the initial silicate, volatile, and metal composition of a
more primitive parent magma.
The concept for the first publication in the 1980’s began when the Magma-Metal Series concept
attracted the attention of Gerhard Westra of Exxon Minerals. Discussions led to the expansion of
the alkalinity fields to include porphyry molybdenum metallogeney and associated igneous rocks and
the discovery that the driving process behind lithophile enrichment in molybdenum related igneous
rock series was differentiation. Included in this work was the creation of time-slice maps based on
molybdenum metallogeny, igneous rock, and isotopic age date data which brought plate tectonics
into the model. Out of this work in 1982 Westra and Keith published “Classification and Genesis of
Stockwork Molybdenum Deposits” in Economic Geology. Because the paper supported the minority
position at the time, which identified the mantle as the source of molybdenum rather than the crust,
it caused a spirited discussion by Christiansen and Wilson in 1982 which Westra and Keith wrote an
extended reply to in 1982 that significantly expanded their model.
Concurrently, with the porphyry molybdenum work, Stan Keith teamed up with Steve Reynolds and
conducted a uranium favorability study of the potential of the newly discovered metamorphic core
complexes of the southwestern US for the Arizona Bureau of Geology. The primary result of this
work was a recast of the “I” (mantle-sourced) versus “S” (sediment-sourced; usually pelitic) granite
distinction into “metaluminous” (mantle-sourced) versus “peraluminous” (crustal-sourced) granite
distinction. This important distinction was presented in the 1983 GSA paper entitled, “A
Geochemical Classification of Peraluminous Granitoids”. This advanced existing peraluminous work
by Shand (1927) and Chappell and White (1974) and shed new light on the petrologic nature of flat
subduction.
About the same time in 1982 Exxon funded the compilation of 15 time-slice maps of the Cretaceous
to Recent magmatic and metallogenic history of the southwestern US. Massive sulfide data from
Mike Fellows of Exxon and gold and base metal data from Hutchinson (1973) and Fox (1978)
added more fields to the K2O versus SiO2 variation diagrams. This work also resulted in the creation
of several variation diagrams that helped to better define additional Magma-Metal Series. This work
was tested with geology and advanced the integration of geotectonics into the Magma-Metal Series
concept.
In 1982 Kennecott Exploration funded a greenstone gold project which showed that Magma-Metal
series and metallogeney are independent of time and geotectonic setting, which had both been used
in published classifications. The project showed that the same Magma-Metal Series relationships we
see today operated in Archean time. In a related gold study in 1983, Michael Parr brought leadingedge data and knowledge of high-magnesium ultramafic magmatism to the concept. Data from
Naldrett and Cabi (1976) and Nardrett (1981) was also added at this time. This ultramafic
contribution to the Magma-Metal Series concept became the basis for MagmaChem’s understanding
of serpentinization in the UDH model. More variation diagrams were developed.
Also in 1983, during a workshop for Mobile Minerals and work on the metallogeny of the Pacific
Northwest for Billiton Exploration, Dick Mishimori based on work in the coastal batholiths
provided insight into the water content of magmas that led to the eventual creation of an iron
enrichment variation diagram that measures the amount of water in a magma series and a reinterpretation of the AFM ternary diagram. This turned out to be an incredibly valuable tool in
determining and predicting geotectonic setting, mantle melting mechanisms, and economic potential
of mineral systems and some petroleum system. This is also an important tool in the evaluation of
geothermal potential.
By this time the screening of mineral systems for specific metal type and economic potential had
begun and was routinely being applied to the evaluation of mineral systems. A Magma-Metal Series
determination for a mineral system was referred to as a “Call”. The primary motivation in making a
“Call” was to identify the system type according to the Magma-Metal Series, which would connect
that particular system to a specific economic track record, thus lowering exploration risk.
Also in 1984 several companies (i.e. Exxon Minerals, Gulf Minerals, and Kennecott Copper)
questioned the statistical treatment of altered igneous rocks. This led to the development of a series
of alteration filter variation diagrams one of which defined the metaluminous/peraluminous
distinction Reynolds and Keith had discussed in their 1983 paper . Additional alkalinity distinctions
were made in 1984 based on data and discussions with Felix Mutschler. This resulted in the
identification of Te-poor Au deposits associated with quartz-bearing alkaline rhyolite systems and
Te-rich Au deposits associated with nepheline-bearing and/or nepheline normative syenite,
monzonite, and phonolites.
By 1984 it was apparent to Stan Keith and Monte Swan that the Magma-Metal Series concept was
paradigmatic and had significant potential as an exploration tool, so they co-founded MagmaChem
Exploration, Inc as a research and business vehicle to facilitate its development. This greatly
accelerated the data base compilation. At one time nearly the whole graduate geology department
was working for MagmaChem in Phoenix compiling and plotting data. One of MagmaChem’ first
projects was the creation of the “MegaChart”, which depicted a layered mantle (Appendix 5). This
was a concept that had been apparent in the Magma-Metal Series data for some time. The chart
graphically presents independently-determined and geophysically-defined layers of the mantle next
to independently-determined Magma-Metal Series layers of the mantle. The near perfect match of
the two layer models together with a survey of mantle xenoliths data was a solid geologic proof of
the layered nature of the mantle. Metallogeny was soon added to the MegaChart at the request of
several mineral companies which expanded the size of the chart to 3 by 13 feet. The layered mantle,
as a geologic layered reference frame of 8 physically immiscible and chemically distinct layers
extending 1000 km into the Earth comprising the Athenospheric mantle. There are 4 way to melt
the various layers: hydrous melting during subduction, adiabatic decompression melting during
rifting, thermal melting during generation of a hotspot. And compressional melting during crustal
thickening usually due to continental collision or flat subduction. By chemically identifying which
melting occurred predictions and correlation with geotectonic settings can be made. So the layered
mantle model soon became the basis for regional mineral and petroleum exploration applications
that led to discoveries and for many geotectonic and plate tectonic insights. Figure 4 and
Appendix 6 is the 2008 version of the MegaChart.
Figure 4: Magma-Metal Series petrochemical model for a layered earth
During the development of the MegaChart, Stan Keith began applying his philosophy background
to the Magma-Metal Series concept and data base, not only in his graphical organization of the
Magma-Metal Series data but in roughing out the logical framework for what would become the
Magma-Metal Series Geochemical Classification of Igneous Rocks and Mineral Deposits. This
classification continued to be refined over the next 15 years. Presented below is a table summarizing
the detailed quantitative conventions and definitions employed at each logical level. A narrative
describing the Classification can be found on pages 1-16 of Appendix 2 Text. Taxonomic clarity is
also aided by the employment of a series of chemical variation diagrams referred to in the narrative.
(Appendix 2 Supporting Figures).
LOGICAL
ORDER
CLASSIFICATION LEVEL TYPE OF CRITERIA
Key References
NOMENCLATURE FOR CRITERIA
DETERMINATION OF CRITERIA
Distinctions based on chemistry of magmatism associated spatially and temporally with the mineral system
1st
Megaseries
aluminum content
Shand (1927)
Chappell and White
(1974)
Reynolds and Keith
(1982)
Keith and others
(1991)
Mitchell and
Bergman (1991)
Sorenson (1970)
2nd
Superseries (2A)
potassium-calciumsodium-magnesiumsilica and Nb-Zr-BaRb-Sr contents.
Silica saturation
Series (2B)
potassium-calciumsodium-magnesiumsilica LREE and NbZr-Ba-Rb-Sr
Peacock (1931)
Kuno (1966)
Dickinson and
Hatherton (1967)
Keith (1978, 1982)
Dawson (1980)
Arndt and Nisbet
(1981)
Keith and others
(1991)
Mitchell and
Bergman (1991)
Sorenson (1970)
peraluminous/metaluminous broadly
equivalent to ("S" vs "I" granitoid
distinction)
peralkaline/metaluminous
(subaluminous)
peralkaline/subaluminous (for
subalkaline and quartz alkaline
metaluminous)
agpaitic/miaskitic (for nepheline
alkaline and leucite alkaline)
agpaitic/perpotassic (for leucite
alkaline superseries)
A/CNK vs. SiO2 variation diagram1 presence of
muscovite and garnet, and monazite
(peraluminous) versus olivine, pyoxene,
amphibole, or sphene (metaluminous)
A/NK vs. SiO2 variation digram2 presence of
one feldspar (anorthoclase), presence of Na
pyroxene or Na amphibole
mol. (K2O + Na2O vs. Al2O3); mol. (Na2O vs.
K2O)2
A/K vs. SiO2 variation diagram3 presence of
leuci te
peraluminous
subalkaline, alkaline
For Peraluminous CaO vs. SiO2, Na2O/K2O vs.
SiO2, Rb vs. Sr, Ba vs. Sr, and CaO vs. Sr plots.
metaluminous
subalkaline, quartz alkaline,
nepheline
alkaline, leucite alkaline
For Metaluminous K20 vs. SiO2, K2O vs. SiO2,
K2O + Na2O vs. SiO2, K20+ MgO vs. Si02, CaO
vs. SiO2, LREE vs. Silica Nb vs. Zr, Rb vs. Sr
plots. Rb-Sr and Sm-Nd isotopes.
peraluminous subalkaline
superseries;
calcic, calc-alkalic series
For Peraluminous CaO vs. SiO2, Na2O/K2O vs.
SiO2, Rb vs. Sr, Ba vs. Sr, and CaO vs. Sr plots.
peraluminous alkaline superseries;
alkali-calcic, alkalic series
metaluminous subalkaline
superseries;
magnesian, calcic, calc-alkalic series
metaluminous quartz alkaline superseries;
alkali-calcic, quartz or hypersthene
normative alkalic
metaluminous nepheline alkaline
super-series;
nepheline alkalic, melilite alkalic
series
metaluminious leucite alkaline superseries;
phlogopite alkalic, leucite alkalic
series
For Metaluminous K20 vs. SiO2, K20-CaO vs.
SiO2, K2O + Na2O vs. SiO2, K20+Na2O-CaO vs.
SiO2. K2O-MgO vs. Si02, CaO vs. SiO2, LREE vs.
Silica Nb vs.Zr, and Rb vs. Sr plots. Rb-Sr and
Sm-Nd isotopes.
K57.5 index4; Peacock alkali-lime index5; K-Ca
index6; K-Mg index7
magnesian series
plagioclase only
calcic series
plagioclase dominant with microcline
appearing in granitic differentiates; quartz
oversaturated
calc-alkalic series
plagioclase dominant with orthoclase
appearing in granitic differentiates; quartz
oversaturated
alkali-calcic series
plagioclase ~K-feldspar with K- feldspar
appearing in monzodiorite system onward;
quartz oversaturated
quartz alkalic series
K-feldspar > plagioclase with K- spar
occurring in the syreno-gabbro system
onward; quartz saturated; hypersthene
normative
nepheline alkalic series
two feldspars; no quartz; nepheline appears
in differentiates
melilite alkalic series
no feldspar (except for orthoclase in high-F
Foyaitic differentiates).
No quartz. Nepheline throughout sequence.
Melilite throughout much of sequence
(especially early).
LOGICAL
ORDER
CLASSIFICATION
LEVEL
TYPE OF CRITERIA
Key References
NOMENCLATURE FOR CRITERIA
DETERMINATION OF CRITERIA
Distinctions based on chemistry of magmatism associated spatially and temporally with the mineral system
2nd (cont.)
phlogopite alkalic
phlogopite occurs in all rock systems;
leucite occurs in differentiates (lamproites);
no feldspar
Series (cont.)
leucite alkalic
leucite can occur in all rock systems
generally no feldspar (except minor
sanidine in some differentiates)
3rd
Subseries
iron content; REE
sample/REE
chondrite HFSE (Nb,
Zr, Y, Ta, V, Hf, Ti,
HREE) content
Fe-rich (also Ti, Y, and V rich)
Fe-poor (also, Ti, Y, and V poor)
Various REE patterns on chondrite
normalized plots such as:
AFM8 ternary diagram or SiO2 vs.
FeO*/MgO variation diagram (Miyashiro
plot); Y vs. Zr, Nb vs. Zr. TiO2 vs. FeO*/MgO,
and V vs. FeO*/MgO plots; REE sample/REE
chrondrite plots HFSE spidergrams
convex upward REE (early rift anhydrous
low K tholeiites)
water content
Wager and Deer
(1939)
Nockholds and
Allen (1953)
Thompson and
others (1984)
Miyashiro (1974)
Keith and others
(1991)
Rock (1992)
convex downward REE (mature high speed
anhydrous rift komatiites)
LREE enriched (vs. flat HREE) (oceanic and
continental weakly hydrous to hydrous
arcs)
Presence of OH-bearing minerals vs.
clinopyroxene and/or orthopyroxene; LOI
and total H2O histograms; oxygen isotopes
LREE depleted (vs. flat HREE) (mature
moderate sppd rift anhydrous NMORB)
Linear HREE to LREE enrichment (EMORB
and OIB’s of various alkalinities)
positive Eu anomaly (anorthositic
subseries)
negative Eu anomaly (ongonitic and
rapakivine mini-series)
anorthositic/anhydrous (tholeiitic)/
weakly hydrous (island arc
tholeiitic)/hydrous (calc-alkaline) /strongly
hydrous (lamprophyric)
Iron enrichment characterizes
anorthositic, and anhydrous clinopyroxene
rich magma series.
Weak iron enrichment characterizes
weakly hydrous magma series.
No iron enrichment is featured in hydrous
and strongly hydrous magma series.
4th
Mini-series
Halogen (F, Cl)
contents
Barberi and others
(1975)
Bailey (1977)
MacDonald (1974)
Christiansen and
others (1983)
Keith and others
(1991)
F-rich, Cl rich (peralkaline in subalkaline or
quartz alkaline superseries or agpaitic in
nepheline alkaline or leucite alkaline
superseries) vs. moderate F, Cl poor
(miaskitic in nepheline and leucite alkaline
superseries ) vs. F-rich, Cl poor (ongonitic in
quartz alkaline superseries) vs. F-poor, Cl
poor (normal metaluminous) vs. moderate
F, Cl poor (rapakivine)
F vs. Cl; Rb vs. Zr plots.
A/NK vs. SiO2 plot
Fluorite is restricted to peralkaline/agpaitic,
ongonitic, or rapakivine miniseries
For ongonitic (presence of topaz)
For rapakivine (presence of rapakivi
orthoclase)
For peralkaline (presence of one feldspar and
Na pyroxene or Na amphibole; sodalite may
occur in basaltic rocks with
'peralkaline'/agpaitic ‘potential')
peralkaline terminology is applied to quartz
LOGICAL
ORDER
CLASSIFICATION
LEVEL
TYPE OF CRITERIA
Key References
NOMENCLATURE FOR CRITERIA
DETERMINATION OF CRITERIA
bearing and quartz saturated sequences.
Agpaitic terminology is applied to quartz
undersaturated, feldspathoid bearing sequences
LOGICAL
ORDER
CLASSIFICATION
LEVEL
TYPE OF CRITERIA
Key References
NOMENCLATURE FOR CRITERIA
DETERMINATION OF CRITERIA
Distinctions based on chemistry of magmatism associated spatially and temporally with the mineral system
5th
Micro-series
oxygen content
sulfur content
carbon dioxide
methane
Osborne (1962)
Wones and Eugster
(1965)
Ishihara (1981)
Czaimanski and others
(1981)
Leveille and others
(1988)
Wones (1989)
Keith and others (1991)
6th
Nano-series
emplacement
level/geologic setting
Buddington (1959)
Hammarstrom and Zen
(1986)
7th
Rock System/Stage
degree of fractional
differentiation
Harker (1909)
Larsen (1938)
Thornton and Tuttle
(1960)
Keith and Swan (1996)
oxidized/reduced--equivalent to
magnetite/ilmenite series distinction
of Ishihary (1981). Specific
terminology is: very strongly
reduced; strongly reduced; reduced;
weakly oxidized, moderately
oxidized; oxidized; strongly oxidized
Fe2O3-FeO ratios, accessory sulfide and
opaque oxide mineralogy; sphene presence
(or absence); magnetic susceptibility; volume
percent of opaque oxides. Fe2O3/FeO vs. SiO2,
A/CNK, and FeO*/MgO plots; S histograms,
sulfur isotopes, hydrogen isotopes F, Cl, C
total, and CO2 histograms; F vs. Cl plots
Intra/supracrustal Emplacement
Levels: hypabyssal (0-1 km)
epizonal (1-3 km)
mesozonal (3-6 km)
katazonal (>6 km)
Submarine Emplacement Levels:
littoral/neritic (0-.2 km)
bathal (.2-4 km)
abyssal (>4 km)
Geobarometry based on hornblende, or
garnet-feldspar geochemistry; wallrock
setting of associated intrusions. For example,
volcanic, hostrocks may be consistent with
shallow level 'hypabyssal' intrusions.
gabbro (basalt)
quartz diorite (andesite);
granodiorite (rhyodacite);
granite (rhyolite)
etc.
silica content; differentiation index (D.I.)9;
Larsen Factor (L.F.)10; A/NK (inverse; Agpaitic
Index); granite (rhyolite) or element ratio on Y
axis vs. D.I., L.F., SiO2, or A/NK plots; oxygen
isotopes; compositional gaps on Harker
variation plots
LOGICAL
ORDER
CLASSIFICATION
LEVEL
TYPE OF CRITERIA
Key References
NOMENCLATURE FOR CRITERIA
DETERMINATION OF CRITERIA
Distinctions based on environment of deposition of the mineral system
8th
Megatype
Setting of deposition
spherical setting [i.e. atmospherelithosphere (subaerial), lithosphere
(intraplate), lithosphere-hydrosphere
(submarine)]
geological interpretations of all available
relevant data
9th
Supertype
Type of deposition
hydrothermal/magmatic [epigeneticsyngenetic/syngenetic only
(exhalitive)]
interpretation of whether fluid deposited
(hydrothermal) or solid deposited (magmatic)
10th
Type
Stage within a
fractional
differentiation
sequence and
conditions of
deposition (P, T, fO2,
pH, fS, emplacement
level, etc.)
Selected serial nomenclature of
associated igneous rocks.
Hotspring/epithermal/mesothermal/
Hypothermal for hydrothermal,
epigenetic, metaluminous systems in
subaerial (atmosphere-lithosphere)
settings; hypomesothermal for
hydrothermal peraluminous systems
in lithosphere settings; and
littoral/bathyal/abyssal for
hydrothermal metaluminous systems
in submarine (hydrospherelithosphere) exhalitive systems.
Mineral deposit place name for the
mineral deposit considered to be the
type location for that particular
deposit (eg. Carlin type).
Mineralogy and chemistry of associated
igneous rock at the rock system level and
fluid inclusion, isotope, microfossil, mineral
stability, mineralogical, paragenetic data, etc.
11th
Subtype
Form of deposition
(morphological and
structural characterics)
Massive sulfide; stratabound, strataform; vein; stockwork; disseminated;
porphyry; skarn; replacement,
manto; nodular, cumulate, etc.
geologic mapping; structural analysis;
interpretation of mineral textures, etc.; i.e.
analysis of the physical properties of the
mineral system
12th
Zone
Composition as a
function of geographic
position within a
specific mineral deposit
type (eg. distal Ag-Mn
leptothermal
zone/fringe of a
mesothermal Pb-Zn-Ag
deposit type)
Principal and minor commodities that
occur within the zone and deposit
name for the mineral deposit
considered to be the type locality for
that particular zone (eg. Prompter
Ag-Mn zone of the Tintic Pb-Zn-Ag
type)
Mineralogy and chemistry of mineral deposit
metal and alteration materials relative to that
of neighboring mineral deposit material
deposited during the same formational event.
NOTES:
1
A/CNK molecular ratio =
2A/NK
molecular ratio =
wt% Al2O3/102
;
when A/CNK > 1.0, the rock is peraluminous. When A/CNK < 1.0, the rock
wt% CaO/56 + wt% Na2O/62 + wt% K2O/94
is metaluminous. From Shand (1927).
wt% Al2O3/102
;
wt% Na2O/62 + wt% K2O/94
K2O<Al2O3) rock
3A/K
molecular ratio = wt% Al2O3/102 ;
A/NK > is the inverse of the more familiar agpaitic index (NK/A). When A/NK < 1.0, the rock is
peralkaline in subalkaline and quartz alkaline cases and agpaitic in nepheline alkaline cases.
From Shand (1927). In nepheline alkaline and leucite alkaline superseries when mol (Na2O +
is miaskitic; when mol (Na2O+K2O)>Al2O3 and mol (Na2O>K2O), rock is agpaitic.
when A/K < 1.0, the rock is perpotassic. All perpotassic rocks may be viewed as a subset of agpaitic rocks
(see
wt% K2O/94
above) and are restricted in occurence to leucite alkaline superseries (see Figure 1). From Mitchell and
Bergman (1991).
4K
57.5 index: weight percent K2O value at 57.5 weight % silica for a suite of igneous rocks plotted on a K 2O versus SiO2 Harker variation diagram. From
Dickinson and
Hatherton (1967).
5Peacock
alkali-lime index: the silica where the quality K2O+Na2O-CaO equals zero for a suite of igneous rocks plotted on a K2O+Na2O-CaO versus
SiO2 variation
diagram (all values are in weight percent major element oxide). Modified from Peacock (1931).
6K-Ca
index:
the silica value where the quantity K2O-CaO versus SiO2 variation diagram (all values are in weight percent major element oxide).
7K-Mg
index: the silica value where the quantity K2O-MgO equals zero for a suite of igneous rocks plotted on a K2O-MgO versus SiO2 variation
diagram (all values are in
weight percent major element oxide).
8AFM
ternary = triangular compositional plot where A = Na2O + K2O at lower left corner, F = total iron as FeO (FeO*) at apex, and M = MgO at lower
right corner (all oxides in weight percent). From Wager and Deer (1939).
9Differentiation
Index (D.I.) = sum of normative (C.I.P.W. or Barth-Niggli) plus albite quartz or nepheline or kalisilite and/or orthoclase. From Thornton
and Tuttle (1960).
10Larsen
Factor (L.F.) = 1/3(SiO2 + K2O - (CaO + MgO + FeO). From Larsen (1938).
Table 1: Criteria for classification of Magma-Metal Series
The MegaChart and the Classification caught the attention of several companies and in 1985 Ray
Morley of Utah Minerals (BHP) requested that MagmaChem catalogue the geochemical threshold
values or “switches” in the Classification and compile them in a geochemical handbook that could
be used for screening exploration plays. An important ratio that came out of this work was the
Ag:Au ratio of 40:1, which identified a mineral system as either a Ag or a Au system. This led to the
search for other “threshold” or “magic” numbers that are characteristic of specific Magma-Metal
Series. It wouldn’t be until nine years later that FMC funded the development of the Expert System
Adviser software to more rigorously document and develop for routine use the empirical
relationships emerging from the Magma-Metal Series Classification. The empiricism which a
MagmaChem “Call” is based on was doubled as a result of this work.
Through discussion with numerous clients from 1984-1986, especially Nigel Grant of Billiton and
with geologists at the United States Geological Survey during a MagmaChem workshop, oxidation
state of a magma series emerged as an important parameter in the tradition of Ishahara (1977). After
several data oxidation state compilation it was discovered that oxidation state for a metal deposit can
be calculated from the ferric:ferrous ratio of the associate igneous rock and directly related to Au:Ag
ratios and in general to the relative abundances (ratios) of metals in mineral systems. In reduced
crust for example where the ferric:ferrous ratio is low (below 1) gold deposits, diamonds, tin, and
hydrocarbon can be present, but are rare in crust where the ratio is above 1. In oxidized crust with a
ferric/ferrous ratio above 1 base metals are maximized and gold is less abundant, and no economic
concentration of diamonds or hydrocarbons occur. Oxidation state also defines strato-tectonic
terranes, major crustal sutures and basement faults and lithology.
One of the greatest challenges facing oil and gas exploration in the WUS is the region's complex
geology. A good example is found in its Sevier-Laramide history (125-43 Ma) which records a
bewildering series of tectonic and hydrocarbon events characterized by diachronous (timetransgressive) geologic sequential overprinting. The term diachronous has been traditionally used to
describe, "similar material in a sedimentary formation varying in age from place to place, usually due
to transgression or regression". The sequence-stratigraphic approach, originally used by Sloss in
1963, was developed to address diachronous sedimentation. This approach, however, limits analysis
to sedimentary rocks and is unable to rigorously address the diachronous complexity of the overall
geology.
To address this challenge during 1984 Rick Livaccari and Stan Keith began a tectonic analysis of the
Sevier (145-85 Ma) and Laramide (85-43 Ma) orogenies in western North America. They constructed
paleo-tectonic time-slice maps and sections. Using Magma-Metal Series they were able to link
oceanic plate motion with continental geology in the western US via petrology and isotopic age
dates--something that had never been done before. They also developed strato-tectonic analysis to
help sort out the diachronous complexity
Strato-tectonic analysis, in contrast to sequence stratigraphy, incorporates structure, metamorphism,
mineral deposits, igneous rocks, isotopic age dates, and plate tectonic data into strato-tectonic
assemblages in a sequence-stratigraphic column-like fashion. An early version of this technique was
first used by Coney (1973) in the form of a chart that combined western US stratigraphic
information with structural phenomena. When these strato-tectonic columns are plotted on timedistance sections, the diachronous complexity and sequential overprinting become obvious. The
individual elements of the overall geology are apparent as is their unique positions in geologic time
and space. The result is a better-constrained tectonic model for the orogenic events.
In several publications and reports strato-tectonic charts of Mesozoic-Cenozoic geology were
combined in time-distance diagrams for the western US (Keith and Wilt, 1985, 1986; Livacarri and
Keith, 1986, 1990). Igneous rock series are a key element of the strato-tectonic charts when
petrochemically-classified as Keith did in 1978 and 1982 using the Magma-Metal Series
Classification. Such treatment allows the division of a generic subduction-related arc complex into a
more resolved petrochemical stratigraphy that is absolutely calibrated to the geologic time scale
using isotopically-dated magmatic rock assemblages. These form an orderly igneous chemical
stratigraphic absolute time/space framework onto which all other data can be plotted and then
integrated with plate tectonic data.
Where the data is poorly constrained, it can be put into regional context on the time-distance section
by analogy with nearby areas adding a testable specify not found in other more generic tectonic
approaches. Tectonic data with varying degrees of confidence can then be synoptically integrated
into regional tectonic models. This brings data not normally used in basin analysis to the basin,
resulting in a more complete and dynamic basin model. Most importantly, tying hydrocarbon events
to strato-tectonic assemblages, not only maps hydrocarbons through time and space, but provides
insights into possible relationships to basement structure and deep-earth processes such as
serpentinization.
In 1985-1986 the Sevier and Laramide paleotectonic maps and sections, 216 page report, annotated
bibliography and seminar was purchased by: Pennzoil, Anschutz, Exxon, Mobil, Texaco, AMACO,
Marathon, Elf Aquitaine, Tenneco, Phillips, Chevron, Unical, Kerr McGee, Exxon Research, and
the United States Geologic Survey.
In late 1986 market conditions shifted in favor of the platinum group elements (PGE). In reaction
to this MagmaChem focused on platinoids. With the help of George Smith correlations between
magma chemistry and precipitation of immiscible sulfide segregations were recognized to be a
function of not only Magma-Metal Series but oxidation state.
In 1987 a Karl Albert with expertise in diamond and kimberlite-lamproite rock systems facilitated a
breakthrough that resulted in the identification of the new Magma-Metal Series of kimberlitelamprophere.
1990-2000 The Earth’s Crust and Mineral Deposit Discoveries
9 Cu-Au-Ag deposit discoveries:
SE Ajo, Arizona 1998 2 billion pounds Cu
Espanola, Chile 1997 6 billion pounds Cu
Espanola, Chile 1997 2 million ounces Au
South Alcaparrosa, Chile 1996 60 million pounds Cu
South Alcaparrosa, Chile 1996 0.15 million ounces Au
Pascua, Chile, 1995 700 million ounces Ag
Tyrone, New Mexico 1994 2.4 billion pounds Cu
South Meikle, Nevada 1992 2 million ounces Au
Vinasale Mountain, Alaska 1992 655,000 ounces Au
26 publications and 52 unpublished works
MagmaChem project topics listed by year:
1990
1991
1992
1993
1994
Geochemical vectoring technique--correlated element assemblages
Geochemical zoning and vectoring of Carlin-type deposits
Assimilation of crustal fluids by magmas
Metal dispersion, sea floor isopachs and exhalite Au, Colorado
Vectoring Vinnsale Mtn, Alaska
Magma-Metal Series and metallogeny, Nevada
Mid-crustal formation fluids
Crust versus mantle as source for metals
Geochemical vectoring Au targeting, Nevada
Mexico metallogenic and Magma-Metal Series compilation
Neural network confirmation of Magma-Metal Series
Pluton vectoring--staged fractionation rock system and metal sequence
1995
1996
1997
1998
1999
Pluton vectoring porphyry Cu targets, Arizona, Mexico
Genesis of the southwestern porphyry Cu cluster
Magma-Metal Series “Call” Expert System Adviser Software
Giant oil fields and crustal oxidation state and slab segmentation
Geochemical-pluton vectoring, Chile, Arizona
Geochemical-pluton vectoring, Chile, Peru
Tectono-metallogenic evolution of Mexico
Thermal infrared emission spectroscopy and granitoid pertrology
Flat plate subduction and continental deformation
Magma-metal differentiation sequence
Strike-slip faults, wet magmas and giant mineral deposits
Cracks of the World, oxidation state, and petroleum
Continued work in the 1990’s by Keith and Swan, MagmaChem employees and associates, focused
on the affect the Earth’s crustal fluids have on Magma-Metal Series traveling through the crust to its
points of deposition. This work resulted in the conceptual development and exploration application
of:
1. Metamorphogenic crustal formational fluids
2. Fault zones as fluid conduits for Magma-Metal Series
4. Fractionation of Magma-Metal Series
Fluid migration (mapping of fluid plumes)
Geochemical assemblage (statistical determination)
Kinematic analysis (predicting fluid migration)
Magnetics and gravity (mapping magma and fluids in basement)
Magma-Metal Series development in the 1980’s was concerned primarily with the source of magma
and associated metal deposits, while Magma-Metal Series development in the 1990’s focused on the
process of the magma and associated metalliferous fluids traveling through and depositing in the
Earth’s crust. The 1990’s work directly addresses the long-standing debate concerning the role of
source and process that can be traced back at least 500 years to Decartes (1644) and Agricola (1556).
In the 1990’s it was discovered that the key to resolving the debate is found in the interaction
between crustal metamorphogenic formationl fluids and rising magmas. Mass-balance calculations,
petrology, Magma-Metal Series fractionation patterns, and structural kinematics applied to fluid
migration demonstrated how source and process integrate. The most spectacular result of this work
and economic proof of concept was the discovery of nine economic Cu-Au-Ag deposits on two
continents.
In 1990 geochemical vectoring was applied to a number of gold prospects in Nevada and from this
work a zoning model for Carlin gold systems was created. Strato-tectonic analysis was applied in
detail to the region from southern California to West Texas. Apparent from this was the crustal
thinning or decretion caused by the flat subduction and the influence this thinned crust had on
middle Tertiary magmatism and deformation as the slab collapsed at 43 Ma. The most significant
discovery was evidence for assimilation of crustal fluids by magmas moving from the mantle
through the crust. It was discovered that the fluid greatly influenced the fractionation of the MagmaMetal Series causing magmas to fractionate along any of seven tracks in a spectrum from oxidized to
reduced. In 1990 MagmaChem compared the economic track records of various gold deposit types
based on Magma-Metal Series and found profound differences that had important exploration
implications.
In 1991 geochemical vectoring studies continued to be applied to Nevada gold prospects
and a formalized geochemical procedure was written by Steve Ruff and Stan Keith using the
Ledge Ridge volcanogenic massive sulfide deposit in Maine as a case history. A layered earth
model was developed by Monte Swan and Stan Keith to highlight the four primary ways to
melt the mantle and the Earth’s crust. This demonstrated the value of Magma-Metal Series
in predicting and unraveling geotectonic settings. Nevada was used as a case history for
demonstrating the application of Magma-Metal Series logic to a world-class gold province. A
resolution for the crust versus mantle source debate was presented by Stan Keith at the Left
Lateral Leap Session at the Northwest Miners Convention in Spokane Washington.
2000-2010 Serpentinization and the Ultra Deep Hydrocarbon Model
13 Cu-Au discoveries and 1 geothermal discovery:
San Luis Potosi, Mexico 2009 (to be determined)*
Lookout Mountain, Nevada 2006 (to be determined?)**
Jewett (Crown Zone), Oregon 2005-6 several thousand tons of +1 opt Au
Big Springs (701/601), Nevada 2005 (to be determined?)***
Rio Figueroa, Chile 2005 (to be determined!?)****
Big Springs (Crusher), Nevada 2005 (to be determined!?)*****
Chuquicamata, Chile 2004 4 billion pounds Cu
Ren, Nevada 2003 1.3 million ounces Au
Storm-Dee Forty Niner, Nevada 2003 1 million ounces Au
Lightning Dock, New Mexico 2002 geothermal test flow 320-325 gpm @ 137°C
Ntotorosa, Ghana, West Africa 2000 2 million onces Au
Pascua, Chile, 2000 26 million ounces Au
*Discovery quality holes for Au
**Discovery quality holes for Au announced December 19, 2005, January 4, 2006 and March 15, 2006
***Discovery quality holes for Au announced November 8, 2005
****Discovery quality holes for Cu-Au announced August 16, 2005 and February 22, 2006
*****Discovery quality holes for Au announced by press releases dated August 11, 2005 and October 18, 2005
22 publications and 38 unpublished works
Project topics listed by year:
2000
2001
Magma-Meta Series chemical classification of Ag deposits
Strike-slip faulting and later differentiation of porphyries
Genesis of Carlin giant Au deposits
Gold deposit models, eastern Russia
Initial work on the UDH Model
Basin analysis--strato-tectonic, oxidation state, fluid zone structures
Hydrocarbons in the earth--petrologic approach
2002
2003
2004
2005
2006
2007
Petroleum geology of Mexico
Petroleum fluid formation, movement and deposition
Basement structure of ancestral Rockies and petroleum western US
Carlin Au analysis, New Foundland
Geochemical vectoring of Lightening Dock geothermal system
Metal production grade/tonnage data base
Magma-Metal Series four volume set (1100 page manuscript)
Strike-slip faulting and reservoir development, New York
Geochemical vectoring Glodes Corner gas field, New York
HTD exploration model and Mg-hydrocarbon source
Cracks of the World, strike-slip faults and giant resource accumulations
Gulf of California source rock study
Five-staged HTD reaction sequence
Carlin geologic maps of the North Carlin Trend
Magma-Metal Series of a Mongolian gold deposit
HTD, white smokers and Cambrian life explosion
Global Cracks of the World map in multiple projections
Hydrothermal oil--integration of hydrocarbons into Magma-Metal Series
Pluton vectoring Au systems, Mexico and Nevada
Basement structure/lithology, petroleum and mineral systems, western US
Metal dispersion structure, Grant Canyon oil field, Nevada
Geochemical and pluton vectoring Cu-Au, Chile
Hydrothermal hydrocarbons--mineral deposit geology to hydrocarbons
Geochemical and pluton vectoring Carlin Au systems, Nevada
Peridotites, serpentinization and hydrocarbons
Magma-Metal Series contributions to discovery
Continued work in the 2000’s by Keith and Swan, MagmaChem employees and associates, focused
on petroleum the process of serpeninization while continuing application of Magma-Metal Series to
exploration, not only mineral exploration but also geothermal and petroleum exploration. This work
resulted in the conceptual development and exploration application of:
1. Serpentinization (discovered to be a first-order Earth process)
2. Oil and serpentinite chemistry
3. Serpentinization mass balance calculations
4. HTD Story (relationship to Green River Oil Shale, Ghawar, etc.)
5. Source rock (black shale) exhalative timeline
6. Re-Os isotopic age dates
7. Supercritical water
8. “Biomarkers” in serpentinite and HTD
9. Serpentinite-hydrocarbon association
10. Kerogen in serpentinites (TOC up to 0.5%)
11. HTD ‘Just-in-Time” arrival of hydrocarbon
12. Mapping hydrocarbon plume fractionation
13. Strato-tectonic analysis of hydrocarbon events
Although MagmaChem did geotectonic work for most of the major oil and gas companies in the
1980's and continued to present papers on the subject in the 1990's, MagmaChem did not begin to
focus on petroleum projects until the UDH project began in 2001. (This was about the time that the
mineral industry experienced a prolong depression in metal prices).
In 2001 MagmaChem prepared a paper for the AAPG meeting in Denver for the purpose of
updating the petroleum industry on MagmaChem’s last ten years of geotectonic work. The subject
of that paper was the application of MagmaChem's geotectonic and deep-Earth story to dynamic
basin modeling. One of the people in the room was the Exxon new-venture leader Barbara
Rassman. She approached MagmaChem and indicated that Exxon had an "accounting" problem for
hydrocarbons in super-giant petroleum systems and perhaps MagmaChem’s deep-Earth story might
provide some insight. She told MagmaChem she had been specifically sent to the conference to find
an answer. Her exact words were, "When we do the accounting for super-giant oil and gas
accumulations the books don't balance. Do you have any ideas from your deep-Earth work how we
can balance the books?"
This led to two short courses with Exxon Research personnel in Houston. While many of the
geologists and geochemists were intrigued with the Magma-Metal Series ideas, a couple of the
geochemists were not and the subsequent interactions with Exxon over the matter stalled.
Encouraged by Exxon’s original question, MagmaChem did an in-house compilation to see if and
how hydrocarbons might fit into the Magma-Metal Series Classification. About this time John
Caprara with EOG expressed an interest in applying Magma-Metal Series to HTD. He introduced
MagmaChem to John Martin of NYSERDA (New York State Energy Research Development
Authority) and together MagmaChem and John Caprara applied for a NYSERDA grant for mineral
deposit thinking to be applied to petroleum geologic problems in New York State--specifically to
address the age and HTD connection of petroleum systems with HTD reservoirs and MVT
(Mississippi valley Type Zn deposits). The team won a grant in 2002. The upshot of that project was
the identification of possible high-magnetic, low-gravity serpentinite sources in the Rhone Trough
(and other rifts) for the fluids that produced the HTD reservoir for HTD gas plays such as Glodes
Corner in Stuben County, New York and the host rocks for the MVT Zn deposits. But
MagmaChem had a surprising result that lead to identification of the natural gas resource some
8,000 feet beneath the ground surface.
Early in the project, basement structural control for the Glodes Corner gas field was recognized and
a kinematic migration model was constructed using aeromagnetic, gravity, remote sensing, geologic
mapping, structural data and kinematic analysis techniques developed in the mineral industry.
Unlike sampling mineral systems, sampling the Glodes Corner gas field directly was not possible, so
it was assumed that a structural kinematic analysis would be the extent of the study. But a surface
soil gas and trace-element data base generated by Direct Geochemical, another NYSERDA research
group, was made available, although not actually released for examination until the results of the
kinematic structural analysis and predicted geochemical patterns were reported to Direct
Geochemical. The result of this “test” was that the patterns were correctly predicted. Although soil
gas geochemical surveys had a good exploration track record at the time, trace-elements and
especially metals, had apparently not been used in this exploration context and especially had not
been used to geochemically “vector” an oil or gas system. The mechanism for transporting metal to
the surface above hydrocarbon accumulations was a new and untested exploration concept, but the
data appeared to be real and was interpreted, revealing patterns that correlated closely with
production and with the kinematic migration model constructed before the geochemical data was
examined. Most importantly, these patterns were reminiscent of patterns seen in mineral systems
Since this work was supported by the New York State government, they encouraged MagmaChem
to put the story out, which MagmaChem did at a NYSERDA conference in Albany New York in
2002; at the AAPG in Salt Lake City, Utah convention in 2003; and at the AAPG convention in
Houston in 2006.
In 2003 Jim Villeneuve of Direct Geochemical in Denver (now Vista Geoscience), introduced
MagmaChem to Brian Crooks of Noble Energy. This interaction was a product of a combination of
MagmaChem’s and Direct Geochemical’s follow-up research regarding the multi-element
geochemical exploration tool for soil geochemical samples taken at Glodes Corner, New York. Brian
Crooks was also interested in other MagmaChem technologies such as the serpentinite-source
model. This gave MagmaChem an audience with Susan Cunningham (formerly with Statoil) who was
especially impressed with an earlier version of our Cracks of the World map that had been initially
supported by Gary Heinmeyer at Phelps Dodge (Cu company) and later by John-Mark Staude at
BHP. Noble Energy then paid MagmaChem to upgrade the Cracks of the World Map and apply the
geochemical exploration tool to suspected hydrothermal hydrocarbon occurrences in the Great
Basin. MagmaChem discovered a spectacular geochemical vectoring pattern at Grant Canyon.
(Subsequent application of this technology by Direct Geochemical to the Snake Valley Play has led
to it becoming a geochemical vectoring case history and exploration play).
The Noble Energy project was initiated in late 2004 and was ongoing in June 2005 when
MagmaChem met Martin Hovland of Statoil at the AAPG Hedburg conference on the origin of
petroleum in Calgary. At that time, Martin asked MagmaChem if they would be interested in looking
at how supercritical water might fit into the Magma-Metal Series concept from a petroleum
perspective. MagmaChem completed the project with Noble in late-2005 and in mid-2006 began the
Statoil UDH project.
Appendices (for MagmaChem History chapter)
1. Contributions of the Magma-Metal Series Approach to the Discovery Process, with sections on
The Magma Metal Series Technical Approach, Magma Metal Series Tools Developed by
MagmaChem to Assist in the Identification and Discovery of Mineral and Petroleum Resources, and
Hydrothermal Hydrocarbons: Keith, S.B and Swan, M.M., 2006,:
2. Magma-Metal Series 4 Volume Set; Text: Keith, S.B., 2002, MagmaChem unpublished
manuscript, 66 pp; Appendix I--76 supporting figures; Appendix II--Model Table, Classification
Chart and Explanatory Text, 347 pp; Appendix III--Grade/Tonnage Table 178 pp.
3. Mineral Deposits, and Geotectonics: Keith, S.B., Magma Series, 1984, Unpublished Report (in
review and under contract for a time with John Wiley and Sons), MagmaChem Exploration, Inc.,
500 pp.
4. MagmaChem Handbook--Geochemical Models of Precious Metal Deposits and Their Empirical
Relationship to Magma Series or How to make MagmaChem “Calls”: Keith, S.B., Swan, M.M. and
Maughan, J.R., 1988, , 250 pp..
5. Metallogeny, Magma Series and Geotectonic Setting of Igneous Rocks: Keith, S.B., 1984,
Unpublished 3 by 13 foot Megachart, Phoenix, AZ, MagmaChem Exploration, Inc.
6. Magma-Metal Series Petrotectonic Model for a Layered Earth: Keith S.B. and Swan, M.M., 2009,
Unpublished chart.
7. Pluton Vectoring for Porphyry Metal Deposits: Keith, S.B., 1994, MagmaChem unpublished
report, 112 pp.
References (for MagmaChem History chapter)
Keith, S.B., 1978, Origins of Arizona Copper Deposits; Hypotheses: Arizona Bureau of Geology
and Mineral Technology, Fieldnotes, v. 8, no. 1-2, pp. 9, 17.
Keith, S.B., 1978, Paleosubduction Geometries Inferred from Cretaceous and Tertiary Magmatic
Patterns in Southwestern North America: Geology (Boulder), v. 6, no. 9, pp. 516-521.
Keith, S.B., 1979, Spatial, Temporal, Chemical, and Structural Evolution of the Southeast ArizonaSouthwest New Mexico Porphyry Copper Cluster: Society of Economic Geologists Field
Conference on Tucson Area Porphyry Copper Deposits, April 1979 Guidebook.
Westra, G. and Keith, S.B., 1981, Classification and Genesis of Stockwork Molybdenum Deposits:
Economic Geology, v.70, no. 4, June-July 1981, pp. 844-873.
Westra, G., and Keith, S.B., 1982, Classification and Genesis of Stockwork Molybdenum Deposits:
Reply: Economic Geology, v. 77, no. 5, pp. 1252-1263.
Keith, S.B., 1982, Paleoconvergence Rates Determined form K2O/SiO2 Ratios in Magmatic Rocks
and their Application to Cretaceous and Tertiary Tectonic Patterns in Southwestern North America:
Geological Society of America Bulletin, v. 93, no. 6, pp. 524-532.
Reynolds, S.J., and Keith, S.B., 1982, Geochemistry & Mineral Potential of Peraluminous
Granitoids: Arizona Bureau of Geology and Mineral Technology Fieldnotes, v. 12, no. 4, pp. 4-6.
Sloss, L.L., 1963, Sequences in the Cratonic Interior of NA: Geol Soc. America Bull., v. 74, no. 2, p.
93-114.
Coney, P.J., 1973, Cordilleran Tectonics and NA Plate Motions: American Journal of Science, v.
272, p. 603-628.
Coney, P. J. and Reynolds, S.J., 1977, Cordilleran Benioff Zones: Nature, v. 270, p. 403-406.
Livaccari, R.F., and Keith, S.B., 1985, Tectonic Analysis of the Sevier (145-85 Ma) and Laramide
(85-43 Ma) Orogenies in WNA: Paleo-Tectonic (Time Slices) Map Folio with Corresponding CrossSections and 3-D Block Diagrams of the Crust and Mantle, Bellevue, WA, MagmaChem
Exploration, Inc., 220 pages.
Keith, S.B. and Wilt, J.C., 1985, Late Cretaceous and Cenozoic Orogenesis of Arizona and Adjacent
Regions; a Strato-Tectonic Approach: in Flores, R.M., and Kaplan, S.S., Editors, Cenozoic
Paleogeography of the West-Central US: Rocky Mountain Section, Society of Economic
Paleontologists and Mineralogists, Denver, CO, pp. 403-437.
Keith S.B. and Wilt, J.C., 1986, Laramide Orogeny in Arizona and Adjacent Regions: a StratoTectonic Synthesis, in Beatty, B and Wilkinson, P.A.K., editors, Frontiers in Geology and Ore
deposits of Arizona and the Southwest: Arizona Geological Society Digest, v. 16, pp. 502-554.
Livaccari, R.F. and Keith, S.B., 1990, Detailed Strato-Tectonic Analysis of the Southern Cordillera
from Trans-Pecos Texas to Southwestern California (abstract): Geological Society of America
Abstracts with Programs, v 22, no. 3, p. 37.