Isotopic and geochemical characteristics of Laramide igneous rocks in Arizona.
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Isotopic and geochemical characteristics of Laramide igneous rocks in Arizona
Lang, James Robert, Ph.D. The University of Arizona, 1991
U·M·I 300 N. Zeeb Rd. Ann Arbor, MI 48106
ISOTOPIC AND GEOCHEMICAL CHARACTERISTICS
OF LARAMIDE IGNEOUS ROCKS IN ARIZONA
by
J ames Robert Lang
A Dissertation Submitted to the Faculty of the
DEPARTMENT OF GEOSCIENCES
in Partial Fulfillment of the Requirements
For the Degree of
DOCTOR OF PHILOSOPHY
In the Graduate College
THE UNIVERSITY OF ARIZONA
1991 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE
As members of the Final Examination Committee, we certify that we have read
the dissertation prepared by ~J~a~m~e~s~R~o~b~e~r~t~L~a=n~g~ ______
entitled ISOTOPIC AND GEOCHEMICAL C~CTERISTICS OF LARAMIDE IGNEOUS ROCKS
IN ARIZONA
and recommend that it be accepted as fulfilling the dissertation requirement
for the Degree of Doctor of Philosophy P /.#_ 7/23/91 ~:~·;(·~4 Date 7/23/91 Mark • Barton Date Ei.Mc~A.~ 7/23/91 Eleanour A. Snow Date
Date
Date
Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy of the dissertation to the Graduate College.
I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement.
7/23/91 ncer R. Titley Date 3
STATEMENT BY AUTHOR
This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.
Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation fl'om or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be oblamed from the aUlhor. ~ Lf4f ~ SIGNED: ~ c;- d 4 TABLE OF CONTENTS
LIST OF ILLUSTRATIONS ....•.•..•••••.•...••.•.••••••••••••••..••••.••••• 7
LIST OF TABLES . . . • . • . • • • • . . . • • . • . • . . . . . • • • • • • • • • • • • . • • • • • • • • • . • . . . . . • . .• 9
ABSTRACf . . • . . . • • . • . . . • • • • • • • • • • . . • . • . • • . • . • . • • • • • • • • • • . • • • • . • • • • . • • . .. 10
CHAFfER 1: INTRODUCTION ....•.•.••.••••••.••••.•••••••.••...••••...•. 11
CHAFfER 2: GENERAL GEOLOGY . . . • . • . • • • • • • • • • • • • • • . • • • • • • • • • • . . . • . . • .. 16
Regional Geolo!tic Setting •.•.••••••..••...•••..••••..•••..•..•••••.•.. 16 Crustal Provinces in Arizona •.....•.•.•..•...••••.•..••••...... ••..•... 18 Criteria for Selecting Igneous Systems for Study •...•••••.••••.....•...•..... 21 Definitions of Productive and Barren Intrusions •..•••.•••••••.•.•...... ••.. 22 Timing and Duration of Laramide Magmatism ....•.•.•••••••.••...... •... 27 A Generalized Description of Laramide Igneous Systems • . • • . • • • • . . . . . • • . • . • • .. 27 Descriptions of Individual Igneous Systems •...••.... • . • . • • • • • . . . • . • • • • . • . .• 29
Ray District ..••.•.....•••.•.••••..••••••.••••.•••...... ••.• 29 Christmas District .•.•.•••••.•••••••••••.•••••••••.•.•..••..•.• 31 Copper Creek District .•.•.•••••••.••.••••.•••••••••..••••.•••.. 33 Safford District .• • • • • . . • • • • • • • . . • • . • • • • • • • . • • • • . • . • • • . • • • • • .• 3S Crown King Stock .•••.••••••••••••• • • • • • • • • • • • • • • • • . • . . . • . . • .• 36 Copper Basin District ..••••.•.••.•••••••••••••••••••..••...•.•. 37 Diamond Joe Stock ...•••.•.•.••••••••••.•.••••••••.•••....•... 37 Bagdad District •...••..•.•••••.•...... ••••..•.•...•.•••.•.•.. 39 Tombstone District .••...•.•••....•..•..•.•..•••..•..•....•.•.. 42 Sierrita District ...•...•...••••••••..••.••....•••...... ••.... 43 Santa Rita Mountains Suite .....•.•....••••••...•..•...... 43
CHAFfER 3: PETROGRAPHY, PETROLOGY, AND ANALYTICAL RESULTS ...... 45
Petrography • . . • . . . . • • . . . • . . • . • • . . . • • . • . . . • • • . • . • • • . • • • . • . . . • • . . • . .. 4S Major Element Geochemistry . . • . • . • . . • • . . • . • . • • • . • • • • • • • • • • . . . • • ...... 51 Rare Earth Element Geochemistry . . . . . • ...... • • . . . . • . • . • . • ...... • 58
A Generalized Pattern of Behavior...... • • . • . . • • • . . • • ...... 58 REE Behavior in Individual Igneous Systems ...... ••.• 62
Sm-Nd and Rb-Sr Isotope Geochemistry ...... • . . . • . . • • . • ...... 69
Representation of Isotopic Data • . • ...... • . • . . . . • . • . . • ...... 69 Results of Sm-Nd and Rb-Sr Isotope Analyses ...... ••.•...... 71 Isotopic Character of Arizona Crustal Provinces ....••••...... 79
Trace and Minor Element Geochemistry...... • ...... • . . . .. 79 5
CHAPTER 4: PRODUCI1VE VERSUS BARREN IGNEOUS ROCKS ...... •.....••.. 94
Major Element Behavior ...•....•.....•...... •...•...... :..... 94 Trace Element Behavior ...... 96 Rare Earth Element Behavior .....•...... •...... •...... 96 Oxidation State ....••.....•...•....•...... ••....•...... •..... 100 Nd and Sr Isotope Behavior ..•..••...... • ...... • . .. 100
CHAPTER 5: DISCUSSION . . . . • ...... • ...... • • . . . . • • ...... 104
Introduction ...... • . . . . . • • • • . . . . . • • . . . . • • • . . • • • • ...... 104 Isotopic Evidence for Components of Laramide Magmas • . . . . • • ...... • . . . .. 105
Nature of the Lower Crust of Arizona .••....•....•...... •.... 105 Isotopic Reservoirs That Contributed to Laramide Magmas ...... 108
Geographic Variations in the Isotopic Composition of Laramide Magmas...... 112
Crust-Mantle Mixing ....•..•..••...... •...... • . . . .. 113 Different Types of Mantle Contribution ...... 113 Different Formation Ages of Crustal Provinces ...... • ...... • • .. 115 Different Isotopic Ages of Crustal Provinces ...... • . . . . • . . . • . . .. 115 Geochemically Distinct Provinces ...... • • • • • ...... 116 Different Petrogenetic Processes ....•••...... •..•...•...... 116
The Nd-Sr Isotopic Array...... • . • • . . • . • . • . . . • . • . . • • ...... • ...... 117 Decoupling of Sr and Eu Behavior .•..•.....•....•.....•...... 120 Rare Earth Element Behavior ...... •...... 123
The Effects of Fluid Loss...... 123 Fractional Crystallization Effects ...... 123 Partial Melting Effects ...... 130
Synthesis ...... •.•...... ••..••..•...... 133
Introduction ...••...... •...••...... •.•...... 131 Processes Affecting Laramide Magmagenesis .....•...... •...... 132 Mechanisms For Producing the Observed Geochemical Behavior ...... 136 Implication of the Models for Metallogenesis ...... •...... 141 Laramide Metallogenesis ...... • ...... 143
CHAPTER 6: CONCLUSIONS...... 146
APPENDIX A: SAMPLE LOCATIONS ...... 148
APPENDIX B: COMPILATION OF RADIOMETRIC DATES ...... 154 6
APPENDIX C: SAMPLE PREPARATION AND ANALYTICAL TECHNIQUES ••...... 159
Sample Collection and Preparation ...... • . . . . • • . . . . • . . . • . . . . • ...... 159 Analytical Techniques for Isotopic Measurements ..••...... 160 Analytical Techniques for Trace Element Analysis . • ...... 160 Whole Rock Analysis • . . . . . • ...... • . • . • ...... • ...... 160
APPENDIX D: ANALYTICAL RESULTS AND NORMATIVE AND MODAL MINERALOGy ...... •.•...... •....•...... 168
APPENDIX E: EQUATIONS AND PARTITION COEFFICIENTS USED IN MODELING ...... • ...... • • • . • . • . . . • • . . . • . . . . • . . . • • ...... 186 Fractional Crystallization ...... •••..•....••....•..••.••...... 186 Batch Partial Melting • . . . • • . • • . . . • • • . . . . . • • . . . • . . . • ...... 186 Assimilation-Fractional Crystallization (APC) ..•.....•..•.•.•...... 186
REFERENCES...... 190 7
LIST OF ILLUSTRATIONS
1.1. Location of study areas...... 15
2.1. Regional tectonic setting of the Arizona Copper Province...... 17
2.2. Geologic and geochemical subdivisions of the Arizona crust...... 19
2.3. Ages of magmatic and mineralizing events in Laramide igneous systems...... 28
2.4. General geology and sample locations in the Ray and Christmas districts...... 30
2.5. General geology and sample locations in the Copper Creek and Safford districts...... 34
2.6. General geology and sample locations in the Copper Basin and Diamond Joe districts. ... 38
2.7. General geology and sample locations in the Tombstone and Bagdad districts...... 40
3.1. lUGS classification of Laramide igneous rocks...... 49
3.2. Aluminosity index versus Si~ for Laramide igneous rocks...... 52
3.3. Harker variation diagrams...... 53
3.4. Age versus Si~ in the Ray and Bagdad systems...... 59
3.5. AFM ternary classification diagram...... 60
3.6. Alkalinity diagrams for Laramide igneous systems...... 61
3.7. Chondrite-norma1ized REE diagrams for the Ray, Christmas, Copper Creek, and Safford districts...... 63
3.8. Chondrite-normalized REE diagrams for the Bagdad, Diamond Joe, Copper Basin, and Crown King districts...... 65
3.9. Chondrite-~o~~d REE diagrams for the Tombstone, Sierrita, and Santa Rita Mountrun distrIcts...... 67
3.10. Plot of eNdr versus Sro' ...... 72 3.11 eNdr and Sro versus age of igneous rocks...... 74
3.12. eNdr and Sro versus Si~...... 75
3.13. eNdr versus liNd, and Sro versus 1/Sr...... 76
3.14. eNd versus time...... •...... 77
3.15. eNdr versus Pb isotope composition...... 80
3.16. Sro versus Pb isotope composition...... 81 8
3.17. Trace element concentration versus SiOz...... • ...... 83
3.18. Relative trace element enrichments in the South and Northwest Provinces versus the Southeast Province...... •...... •...... •...... 87
3.19. Relative trace element enrichments in the South versus the Northwest Province...... 88
3.20. Summary of relative enrichments of LILE, HFSE, and FRTE in the Southeast, South, and Northwef.t Provinces...... 89
3.21. Trace element variation diagrams plotting Ba versus La, Zr, Rb, and Th...... 91
3.22. Th-Hf-1OTa ternary diagram...... • ...... 93
4.1. Comparison of major and trace element compositions of productive and barren igneous rocks...... •...... •...... 95
4.2. Trace elements that distinguish productive and barren igneous rocks...... 97
4.3. Chondrite normalized REE proflles of barren and productive igneous rocks...... 98
4.4. I:LREE and I:HREE versus Eu/Eu· for productive and barren igneous rocks. • ...... 99
4.5. Relationship between F'2 ~ and FeO in productive and barren igneous rocks...... 101
4.6. Relationship between ENdr and Sro in productive and barren igneous rocks...... 103
5.1. Compilation of ENd values of Precambrian crust, lower crustal xenoliths, and Mesozoic igneous rocks in the Southwest...... •...... 107
5.2. ENdr versus Sro plot with isotopic reservoirs indicated...... 109
5.3. ENd versus age plot, and mechanisms for generating provincial isotopic differences...... 114
5.4. Binary Nd-Sr isotopic mixing curves between mantle and crustal reservoirs. . • ...... 118
5.5. AFC models applied to the relationship between ENdr and Sro' 119 5.6. Relationship between Sro and Car' ...... 122
5.7. Frac~io~al crystallization models applied to REE behavior in the Ray and Christmas dIStrictS...... • • ...... • ...... 125
5.8. Fractional crystallization and APC models for the relationship between K/Rb and Rb. .. 128
5.9. Generation of early volcanic melts in the Laramide magmatic arc ...... 134
5.lD. Models describing the generation of intrusive rocks in the Laramide arc ...... 137
5.11. Effects on REE behavior of source hybridization by fluids...... • ...... 139
C.l. Comparison of Nd, Sm, Sr, and Rb concentrations as determined by isotope dilution and ICP-QMS techniques...... 163 9
LIST OF TABLES
2.1. Summary of pluton productivity ...•••••.•..•••.•••.••.••••••..•.•..••...... 24
3.1. Samples affected by minor hydrothermal alteration • . . . • • • . • . • • • . • • • . . • • • • . . . . • .. 46 A.I. Sample locations . • • . • • • • • • . • • . • • . • • • . • . . . • • • • • • • • • . • • • • • • . • . • . . . • • . . .• 149 B.I. Data for new K-Ar dates • • . . . . • . . . . • • • . • • . • • • • • • • . • . . • • . . • • • . • • • • • • • . • .. 155 B.II. Compilation of published radiometric dates from some Laramide magmatic centers in Arizona ...... 156 C.I. Analytical results on the LaJolla Nd and the NBS-987 Sr isotope standards...... 163
C.II. Results of replicate isotopic analyses •.....••••...... ••..•...... 164
C.III. Statistical data on analyses of USGS whole rock standards RGM-l, SCQ-l, and W-2 .. 165
C.IV. Comparison of Nd, Sm, Sr, and Rb concentration data obtained by isotope dilution and by ICP-MS techniques. • . • • • • . . . . • • • • . . • • • . . . .• . • • • • . . . . . • • . • . . . .. 166 D.I. Results of whole rock analysis for major elements, and ClPW norms •...•.•..••.... 169 0.11. Results of analysis for trace element composition .•.•••••.••.••••..•....•••..• 173
0.111. Sm-Nd and Rb-Sr isotopic data ..••••...•••.•••.•••••.•••••..•..•••.••.• 178 D.IV. Modal mineralogy of samples . . . . • • • • . . • • • • . . . • ...... • • • • . . . . • . . . • . . .. 181
D.V. Rock names of samples according to lUGS classification ...•..••••••...•.••.... 184
E.I. Mineral melt partition coefficients for acid and basic compositions, as used in modeling calculations ...... ,...... 189 10 ABSTRACf
Isotopic and trace element data on igneous rocks in nine multiphase magmatic complexes of
Laramide age in Arizona place constraints on their petrogenesis and on the factors leading to the
formation of porphyry copper deposits.
The igneous rocks form a data array from fNdr and Sro values of 0 and 0.704, to -14 and
> 0.710, respectively. Isotopic compositions indicate that early, intermediate volcanic rocks retained a
mantle component whereas later intrusions were derived predominantly from Precambrian lower
crust. The REE display temporally systematic behavior. Progressively younger igneous rocks in a
district show a decreasing concentration of REE which is more pronounced for the HREE than for
the LREE; they acquire greater upward concavity in their HREE profUes; and the Eu anomaly
steadily becomes less negative. A increasing role for hornblende is indicated, either in the residuum
of melting or as a fractionating phase. The evolving REE and isotopic behavior parallels the
progression from barren, to subproductive, to productive intrusions.
The geochemical behavior can be understood in the broader context of magmagenesis at the
Laramide convergent margin. Early in the Laramide, the crust was cool and brittle, thereby allowing
magmas formed in the mantle wedge as a consequence of volatile loss from the descending slab to
ascend to high crustal levels. As the crust warmed the ascent of mantle-derived magmas was
arrested in the lower crust where they induced anatexis in Precambrian crust. Three related models
can account for the systematic REE behavior, crustal anatexis, and the timing of Laramide
metallogenesis: 1) metasomatism of the lower crust, 2) progressively greater assimilation of hydrous
crust by mantle-derived melts, and 3) migration of the anatectic zone into more hydrous rocks at
higher crustal levels. Each process would allow melting to continue in confined columns of crust as well as provide increasingly volatile-rich magmas that were necessary for melts to evolve fluids capable of forming large porphyry copper deposits. The ultimate ability of a melt to form a porphyry copper deposit may, therefore, depend on characteristics obtained either in its crustal source region or during its passage through the crust. 11
CHAPTER 1
INTRODUCI10N
The Arizona porphyry copper province is one of the most prolifically mineralized regions on
Earth. The most abundant and economically important mineralization in this area formed during the Laramide event, an episode of tectonism,magmatism, and metallogenesis that affected southwestern North America between 80 and SOMa during a time of northeast-directed subduction of the Farallon plate beneath the western margin of the North American plate. Laramide metallogenesis in the Southwest is dominated by the nearly 40 known occurrences of porphyry copper-style deposits, most of which are in Arizona. These metallogenic systems are intrusion centered, large tonnage, low-grade deposits with a metal assemblage comprising eu with lesser Mo,
Ag, and, less commonly, Au; they commonly have economically important vein, skarn, and carbonate replacement deposits associated with them. They owe their genesis to the emplacement of felsic, intermediate to acid, hypabyssal, porphyritic intrusions (Titley and Beane, 1981) that formed above the active subduction zone. The porphyry deposits, however, did not form as temporally random, or spatially isolated events in this region but rather as one specific stage during the maturation of complex magmatic centers that progressed through a long-lived sequence of igneous events. This type of convergent margin magmatism has received considerable attention in recent years (for a recent summary refer to Wilson (1989» and it is now recognized that arc magmas result from a complex interplay of source and process involving both mantle and crustal components (Hildreth and
Moorbath, 1988). The factors that control the progressive generation and evolution of magmas in these systems must, therefore, be addressed if the associated metallogenesis is to be better understood.
The study of Laramide magmatism and metallogensis must also take into account influences exerted by the Precambrian continental crust. Farmer and DePaolo (1984) demonstrated through a study of Nd and Sr isotopes that ancient continental crust forms an important, and in some cases a 12 dominant, component of igneous rocks in the Southwest. Furthermore, the metal assemblage of mineral deposits is closely linked (Titley, 1987, 1991; Titley and Anthony, 1989) to geochemically discrete blocks of continental crust now recognized in this region (Bennett and DePaolo, 1987;
Wooden et al., 1988; Titley, 1981). The crust is apparently influencing metallogenesis.
The intimate temporal and spatial association of porphyry copper deposits with igneous rocks generated in magmatic arc environments at convergent plate boundaries is unequivocal, and establishes that a genetic link, albeit one that is inadequately understood, exists between them. The ability of magmas with intermediate compositions to exsolve metal-charged fluids capable of forming large base metal deposits has been repeatedly demonstrated (Holland, 1972; Candela and Holland,
1986; Candela, 1989; Nakano and Urabe, 1989). Furthermore, stable isotope studies reveal that the formation of potassic alteration assemblages, and presumably the accompanying mineralization, that form early in the evolution of these deposits is dominated by magmatic waters (Sheppard and
Nielsen, 1971), notwithstanding the complications introduced by the formation of paragenetically later styles of alteration and the redistribution of earlier-deposited metals by circulating meteoric waters. Magmas are, therefore, implicated as the immediate source of the metals in porphyry copper deposits. If the metals are indeed derived from the magmas, the long-recognized divergence of plutons in porphyry-mineralized provinces into a productive group genetically associated with the deposits and a barren subset that lacked the capacity to concentrate base metals efficiently is a feature critical to gaining insight into their formation. The barren-productive subdivision is a general property of igneous-associated metallogenesis that is ubiquitous among porphyry-mineralized districts, including the Andes (Baldwin and Pearce, 1982), the Southwest Pacific (Mason and
MacDonald, 1978), the Caribbean (Kesler, 1973), and southwestern North America. The macroscopic similarity between barren and productive igneous rocks has prompted many workers to seek geochemical characteristics that discriminate between them, particularly as an aid to mineral exploration. With varying degrees of success, studies have addressed differences in major element composition (e.g., Creasey, 1984; Mason and MacDonald, 1978; Mason and Feiss, 1978; Feiss, 1979), trace clement composition (e.g., Bolin, 1976; Baldwin and Pearce, 1982), crystal chemistry and 13
oxidation state (e.g., Kesler et al., 1975; Mason, 1978; Mason and MacDonald, 1978), and isotope
geochemistry (Farmer and DePaolo, 1984). These studies have established many important aspects
of porphyry copper genesis, but they have not been able to determine whether the productive-barren
subdivision arises as a consequence of influences exerted by, or components derived from, the
magma source, assimilated crustal materials, unique differentiation pathways, or characteristics of the
immediate environment of emplacement.
In the voluminous literature on porphyry copper deposits, most studies have concentrated on
subsolidus, hydrothermal processes, and these are now relatively well understood. Unfortunately,
few studies have considered the formation of porphyry deposits in the broader petrogenetic evolution
of the long-lived magmatic systems of which they are a part, or with respect to the characteristics of
the crust in which they occur and through which the associated magmas have passed. If greater
understanding of the relationship between metallogensis, magmagenesis, and crust formation is to be
gained these must be considered in concert. The occurrence of porphyry copper deposits in several
discrete crustal provinces and the abundance of background information on porphyry systems in
Arizona makes this regi?n an excellent laboratory for applying an integrated approach to addressing
the relative controls that source, process, and environment played in their formation.
This study reports new data for the major and trace element composition and the Sm-Nd and Rb-Sr isotope composition of volcanic and intrusive rocks in nine Laramide magmatic centers across Arizona (Fig. 1.1). Productive igneous systems that formed porphyry copper deposits in the course of their magmatic evolution include Ray, Christmas, Copper Creek, Bagdad, Copper Basin,
Safford Dos Pobres, and Safford Lone Star. Magmatic centers that are thought to be barren of porphyry deposits were also examined, and these include the Tombstone district, the Diamond Joe stock, and the Crown King stock. The new data build upon earlier studies of the igneous rocks in the productive Sierrita system (Anthony and Titley, 1988) and on a study of a suite of economically barren rocks in the Santa Rita Mountains (Trapp, 1987). Geochemical data were also acquired from several examples of Precambrian basement rocks to assess their potential role in the petrogenetic history of the Laramide magmas. This study has generated a database from which constraints can be 14 placed on: 1) the geochemical characteristics of Laramide magmas, 2) the progenitors that may have been involved in their generation, 3) their petrogenetic evolution during passage through the crust and during their residence in upper level magma chambers, and 4) the factors that contributed to their grouping into productive and barren subsets. 15
II °0 III Nevada ~I~~t,..a'!"lh'!"lI.,.II+rII.-mIr-M1 +i--!',..II~T+'';';':,_-:'~: ;~; :~i '*:;.;.~~OO
Little Rincon o Little Dragoon o 0 I Sierrita... Dos Cabezas Santa Rita Tombstone O~100~ Mtns i km Mexico
Figure 1.1. Location of study areas. Filled circles are Laramide magmatic centers; open squares are sites where Precambrian basement was sampled. Vertically ruled area is the Colorado Plateau physiographic province, the shaded area is the Transition Zone, and the open area is the Basin and Range Province. 16
CHAPTER 2
GENERAL GEOLOGY
Regional Geologic Setting
The geologic setting of the porphyry copper province of southwestern North America has
been discussed by Titley (1981), TitIey and Beane (1981), and TitIey and Anthony (1989). In this
study the term 'Arizona Copper Province' encompasses the areas of Arizona, southwestern New
Mexico, and northern Mexico that contain porphyry Cu-Mo-Ag:tAu deposits (Fig. 2.1). In a fashion similar to other circum-Pacific porphyry provinces, the deposits of the Arizona Copper Province formed above an actively subducting slab in a mobile zone lying between a belt of batholiths near the coast and an uplifted cratonic interior. Plate reconstructions (Engebretsen et aI., 1985) are consistent with the interpretation of many workers that a period of stable subduction of the Farallon plate beneath North America continued through most of the Cretaceous. Beginning in the late
Cretaceous, magmatism migrated progressively inland, eventually affecting areas over lOOOkm from the trench (Coney and Reynolds, 1977), before sweeping back toward the trench in the Tertiary.
The onset of Laramide magmatism in Arizona approximately coincides with the initiation of the eastward magmatic migration. In Arizona plate convergence was directed toward the northeast until about 75Maj it then shifted to the north-northeast until at about SOMa it swung back again to the northeast (Fig. 2.1j Engebretsen et aI., 1985).
Every known porphyry copper deposit in the Arizona Copper Province formed within either the Transition Zone or the Basin and Range physiograpic province (Fig. 2.1). The deposits are hosted by a great variety of rock types including Precambrian rocks, Phanerozoic sedimentary and igneous rocks, and by other Laramide rocks. Although worldwide the basement to porphyry provinces as a group is extremely variable and is often only poorly known, the Arizona Copper
Province is everywhere known to be underlain by Proterozoic crust. 17
Figure 2.1. Regional tectonic setting of the Arizona Copper Province. The arrows show relative convergence directions between the North American and Farallon plates at 75 and SOMa (Engebretsen et aI., 1985). The figure is modified slightly from Titley (in press). 18
The magmas that are associated with porphyry deposits are usually only one phase in a
magmatic continuum that affected a given, localized area of crust. The magmas include basic to
acidic volcanic rocks and intrusions, but intermediate compositions are most common. Titley (1981)
suggested that in southeastern Arizona these intrusions were localized along major northeast- and
northwest-trending structures. East-northeast directed stress fields resulted in north-northwest
dilation that may, in part, account for the largely passive emplaceUlent of the intrusions (Rehrig and
Heidrick, 1976). This structural environment might also explain why these magmatic centers usually
remain areally discrete from each other.
Crustal Provinces in Arizona
The Precambrian crust of Arizona has had a complex geologic history that is important to
the understanding of Laramide magmagenesis and metallogenesis. The Precambrian crust beneath
Arizona formed predominantly as a juvenile extraction from the mantle between 1.7 and 1.8 Ga
(Farmer and DePaolo, 1984; Bennett and DePaolo, 1987). The spel.'ific tectonic environment during this crust-forming event continues to be debated but may have involved the accretion of a series of magmatic arcs (Condie, 1982; Anderson, 1986) or a more complex history of accretion of tectonostratigraphic terranes (Karistrom and Bowring, 1988; Bowring and Karlstrom, 1990). Within the framework of this complicated tectonic history geologic, geophysical, geochemical, and isotopic evidence reveals the presence of a number of geologically and geochemically discrete crustal provinces. Because the Laramide igneous rocks of interest here are widely distributed, and wiII be shown below to have inherited many geochemical traits from the crust, a brief discussion of the distribution of these crustal provinces is warranted.
Isotopic data identify a complicated pattern of crustal provinces (Fig. 2.2). Wooden et aI.
(1988) identified the Mohave, Central Arizona, and Southeastern Arizona provinces from Pb isotope data on Precambrian rocks. The southeastern boundary of the Mohave province has recently been refined by Chamberlain and Bowring (1990) who recognized igneous zircons with a inherited 2.0 to
2.3 Ga component on the Mohave side of the boundary and the absence of this older component to the southeast. The boundary between the Mohave and Yavapai/Central Arizona provinces is 19
11111111 Utah
Z! ,=:;ID I
/ .I 7,/ "1'..... © _i ~ S8 ~~~ @ 'G.. O~'b ",0 / ...... ~ ~. Southern Arizona '- '~~\'lJl.,\ N Terrane ® <:) ...... o 7 O~~50__ iiiii1ii!00~~ SR ® j km
Figure 2.2. Geologic and geochemical subdivisions of the Arizona crust. The vertically ruled area is the Colorado Plateau, the shaded area is the Transition Zone, and the open area is the Basin and Range Province. Heavy solid lines demarcate provinces based on Nd isotopes (Bennett and DePaolo, 1987). Heavy dashed lines separate Pb isotope provinces (Wooden et al., 1988). Heavy dotted line is the boundary between rocks underlain by > 2.0Ga and < 1.8Ga crust to the northwest and southeast, respectively (Chamberlain and Bowring, 1990). Dash-dot line separates southeastern from northwestern Arizona based on the crystallization ages of Precambrian rocks (Titley, 1981; Conway and Silver, 1989). Light, solid lines with dashed extensions are magnetic lineaments that divide the Southeast Arizona/Pinal Schist Terrane from the Yavapai Terrane and the Northwest Gneiss Terrane (TitIey, 1981). Lettered, open hexagons are Laramide magmatic centers: T, Tombstone; SR, Santa Rita Mountains; S, Sierrita; SB, Silverbell; L, Lakeshore; A, Ajo; SF, Safford; C, Copper Creek; CH, Christmas; R, Ray; CK, Crown King; CB, Copper Basin; B, Bagdad; D, Diamond Joe; MP, Mineral Park. 20
probably transitional. Wooden and Tosdal (1990) cite further Pb isotope evidence that implies the
presence of a South Province; this province coincides broadly with the distribution of igneous rocks
related to Jurassic arc magmatism. Bennett and DePaolo (1987) proposed crustal provinces based
on the Nd isotope composition of Precambrian intrusions but their subdivisions are not strictly
coincident with those dermed by Pb isotopes.
Geologic observations yield a simpler subdivision of the Arhona crust. This subdivision
remains consistent with the more complicated pattern of isotopic provinces, and it bisects Arizona
into Northwest and Southeast Provinces (Titley, 1981; Anderson, 1986; Condie, 1982). The dividing
line between these provinces is the Moore Gulch fault zone (Conway and Silver, 1989). Differences
between the two blocks of crust include: 1) rocks in northwestern Arizona have older maximum
crystallization ages (> 1.72Ma) than in the southeast « 1.70Ga), 2) acid to basic volcanic rocks are
an important constituent of Precambrian rocks exposed in the Northwest Province whereas the
Southeast Province is dominated by metasedimentary rocks, 3) ore deposits in the northwest have
consistently higher ratios of gold to silver than ores in the southeast (Titley, 1991), 4) the Pb isotope
composition of galenas from ore deposits (Bouse et al., 199Ob) is distinct between the two provinces,
irrespective of the age or style of mineralization, and 5) porphyry copper deposits, and Laramide
igneous rocks generally, are much more abundant in the Southeast Province and contiguous portions of New Mexico and Mexico (Figs. 2.1 and 2.2). Titley (1981) observed that the division between the
Northwest and Southeast Provinces coincides with the Holbrook magnetic linear (Fig. 2.2). The
Bright Angel/Mesa Butte linear (Shoemaker et al., 1978) is a second, similar linear magnetic anomaly that lies further to the northwest and coincides broadly with the northwest margin of the zone of transition in Pb isotope composition between the Mohave and Central Arizona Provinces
(Wooden and DeWitt, in press). These magnetic lineaments approximate the borders of the
Colorado Mineral Belt to the northeast but, whereas they remain distinct beneath the Colorado
Plateau, they become diffuse and are lost as they emerge from beneath it to the southwest. Their extrapolated southwestard extensions continue along zones that have different characteristics in surface geology (Shoemaker et al., 1978). 21
In the remainder of this study, except when specifically stated as otherwise, the simpler
geologic subdivision of Arizona into a Southeast and Northwest Province is used. In general, the
Southeast Province also includes what is called the South Province, as defmed by Pb isotope studies
and the distribution of Jurassic arc rocks.
Criteria for Selecting Igneous Systems for Study
The Laramide igneous systems selected for study (Fig. 2.2) include the six complexes that
host the Ray, Christmas, Copper Creek, Safford Lone Star, Safford Dos Pobres, Copper Basin, and
Bagdad porphyry copper deposits. Three additional Laramide igneous systems, the Crown King,
Diamond Joe, and Tombstone districts, were selected because they do not contain any known
porphyry copper mineralization. Data acquired on the mineralized Sierrita system by Anthony and
TitIey (1988) and on a suite of unmineralized Laramide igneous rocks in the Santa Rita Mountains by Trapp (1987) are the only published studies that address in detail the geochemistry of long-lived,
Laramide igneous systems in Arizona. The types of data generated in those studies are sufficiently similar to the approaches taken in this study that they will be frequently discussed in conjunction with this work. Some scattered additional data exist in the literature for other Laramide igneous rocks in Arizona and the locations of those that are discussed here are also shown on Figure 2.2.
Several criteria were used to select igneous systems with characteristics suitable for this study. Systems were sought in which: 1) the magmatic and mineralizing events had been sufficiently well characterized by radiometric dating and field relationships to discern the relative timing of individual events, 2) a broad range in mineralogical and geochemical variation representative of these systems as a whole was obtainable, 3) the specific igneous units responsible for the porphyry mineralization had been identified, 4) productive and non-productive systems from both the
Northwest and Southeast crustal provinces were represented, and 5) samples that were reasonably free from the effects of hydrothermal alteration were available. 22
Definitions of Productive and Barren Intrusions
One of the primary objectives of this study was to identify factors that contributed to the
relative productivity of individual Laramide stocks or igneous systems. However, because of the
subjective nature of classifying plutons into barren, subproductive, and productive subsets, some
discussion of the criteria for their categorization is warranted here. The following definitions and
criteria have been applied:
.- Barren stocks lack zoned, disseminated or veinlet-controlled (Titley, 1982b) enrichments in
the base metals and, usually, they also lack the patterns and scale of hydrothermal alteration
that typify porphyry-style deposits (Beane and Titley, 1981).
Subproductive stocks are associated with enrichments in the base metals significantly above
background levels, usually taking the form of veinlet-controlled or, more rarely, disseminated
mineralization, but only small tonnages of mineralized, usually low-grade material resulted.
Productive stocks are intimately related to the formation of significant tonnages of material
of ore or subore grade. Mineralization may occur in the disseminated and/or veinlet
controlled styles, and zones of hydrothermal alteration are usually widespread. The
mechanism or specific genetic link between magma and ore is not critical to their
classification as productive stocks. Productive stocks differ from mineralized stocks in that
the latter may act as hosts to ore without a direct genetic link to mineralization. To be a
productive stock does not require any economic production of metals to have taken place.
Accurate classification of the productivity of an intrusion depends upon our ability to identify
which pluton(s) in a system have sufficient temporal and spatial relationships to the mineralization to
have had a probable genetic link to formation of the deposit, irrespective of the nature of the actual genetic bond between a pluton and its mineralization. A shortcoming of some earlier attempts to distinguish between productive and barren intrusions was to incorrectly classify some rocks as productive that probably served merely as hosts to mineralization and were not directly linked to ore 23
formation. Each of the systems in this study has reasonable geologic evidence pointing to a specific
pluton(s) as responsible for the mineralization. This evidence includes, for example, fracture pattern
analysis at Sierrita (Titley et aI., 1986), zoning patterns of alteration and mineralization at Christmas
(Koski and Cook, 1982), Bagdad (Blacet, 1983) and Ray (Phillips et aI., 1974) and radiometric dating
at Ray (Banks and Stuckless, 1973; Banks et aI., 1972). Table 2.1 summarizes the productivity of
Laramide igneous rocks considered in this study.
In order to justify categorizing some plutons as productive their possible physical
relationships to the associated mineralization must be considered. The exposed portions of
'productive' stocks must be considered pre-ore because they were subjected to brittle fracturing and
became hosts to mineralization. It is more likely that they represent the carapace of the magma that
Was responsible for producing the mineralization and alteration within the framework of its
crystallization history and thus were probably not emplaced at a time significantly different from the
mineralizing event itself. The Mineral Park system is an instructive example. Fluid inclusion evidence suggests that the exposed Ithaca Peak stocks served as fractured conduits for hydrothermal fluids ascending from deeper levels in the magmatic-hydrothermal system (Lang and Eastoe, 1988).
Igneous textures within the stocks, however, (Kirkham and Sinclair, 1988) suggest that even the fractured rocks that host ore in the exposed portion of the orebody were themselves episodically exhaling fluids and forming higher, subsequently eroded levels of the deposit. The textural observations of Kirkham and Sinclair (1988) show that 'pre-ore' host rocks need not have been much removed either temporally or spatially from the source of mineralizing fluids. Continuity of mineralization to at least IS00m depth (Wilkinson et aI., 1982) suggests that ore formation was an ongoing process that retreated downward in company with the crystallization of the Ithaca Peak stock. Therefore, exposed, fractured intrusions can reasonably be considered productive.
Laramide igneous rocks in Arizona aggregate into areally discrete systems. In these systems the magmas are probably related in various, but usually uncertain, ways and degrees. Accurate defmition of the boundaries of these systems is not always c1earcut. Some of the distinction between systems might arise as an artifact of Basin and Range exposure because igneous rocks that are 24
Table 2.1. Summary of Pluton Productivity
System Igneous rock units Mineralization
Ray and Williamson Canyon Volcanics none Christmas Tortilla Quartz Diorite none MacDonald Stock none Rattler Granodiorite-basic none Rattler Granodiorite-acidic minor stockwork Cu Teacup Granodiorite minor bx with Cu Christmas Intrusive Complex Christmas PCD'" Granite Mountain Porphyry Ray PCD Teapot Mountain Porphyry minor Cu min'l Stage V Rhyodacite none
Safford Safford andesite none Lone Star Stock and equivs. none Dos Pobres porphyry Dos Pobres PCD Lone Star porphyry Lone Star PCD Baboon Metavolcanics none
Copper Creek Glory Hole Volcanics none Copper Creek Granodiorite none Pink dacite porphyry none Dark dacite porphyry Copper Creek PCD
Tombstone Bronco Volcanics none Schieffelin Granodiorite none Uncle Sam Tuff none Rhyodacite stock none Hornblende andesite dikes Pb-Zn-Ag veins Tombstone Rhyolite minor Mn-Ag veins
Sierrita Diorite stocks none Demetrie Andesite none Red Boy Rhyolite none Ruby Star Granodiorite none Late porphyries Sierrita PCD
Santa Rita Mountains Salero Formation none Empire and Corona stocks none Josephine Canyon Diorite none Elephant Head Quartz Monzonite none Greaterville Intrusives none?
Diamond Joe all phases rare, isolated CuoMo veins
Crown King main phase granodiorite minor Cu-Mo bx pipes; multi-metal peripheral veins 25
Table 2.1. Continued.
Copper Basin Border phase diorite none Main phase granodiorite none older quartz latite porphyry Copper Basin PCD younger quartz latite porphyry minor Cu stockwork
Bagdad Grayback Mountain tuff none Rhyolite dikes none Blue Mountain Stock none Bagdad stock none Southwest stock ?Cu-Mo stockwork? diorite porphyry dikes none qtz monzonite porphyry dikes ?Cu-Mo stockwork? porphyritic quartz monzonite Bagdad PCD granite porphyry dike minor CuoMo min'l
'" PCD = porpbyry copper deposit 26
similar to the exposed Laramide plutons have been intercepted by drilling beneath the valley cover
and therefore the full distribution of Laramide magmas is not known. Furthermore, because not
every igneous system contains porphyry mineralization the productivity of systems, rather than
individual plutons, might be an alternative perspective for consideration. The defInition of
productive, subproductive, and barren systems is more problematic than for single plutons. For
example, the Tombstone system does not contain any known porphyry copper mineralization, but it
does host an extensive system of Pb-Zn-Mn-Ag veins that are similar to veins in some porphyry
copper deposits, and metal zoning patterns (Newell, 1974) suggest that viable exploration targets
exist for porphyry mineralization at depth. Several generations of dikes exist, including a type that is
associated with the vein mineralization, that may be emanating from deeper, unexposed, and possibly
mineralized, intrusions. The Crown King district also lacks a porphyry deposit but it does host
several small breccia pipes that contain low grade CuoMo mineralization (Ball, 1982), and the stock
is surrounded by an extensive system of base and precious metal-bearing veins. Both styles of
mineralization are common associates of porphyry deposits (Walker, 1979; Lang and Eastoe, 1988)
and are not unlike the mineralization found in the productive Copper Creek system (Guthrie and
Moore, 1980). Thus, upon closer inspection the classillcation of the productivity of these systems is
not always straightforward.
The effect that the level of erosional exposure may have on the interpretation of the
productivity of the constituent stocks in a system, or a geographic region, remains unclear. Porphyry
systems form mineralization over a large vertical extent, and what may be classilled as a barren stock
on the basis of the current level of exposure may have had signillcant mineralization removed from a
not much higher level. Erosional level may also contribute to the paucity of Laramide magmatism
and mineralization in northwestern Arizona. In southeastern Arizona, signillcant exposures of
volcanic rocks are preserved whereas in northwestern Arizona Laramide volcanic rocks are rare (the
Grayback Mountain Tuff in the Bagdad district is an exception). Similarly, exposures of
Precambrian rocks in northwestern Arizona have higher metamorphic grades than in southeastern
Arizona (Anderson, 1986). Igneous textures, the presence of open space mineralization, and fluid 27
inclusion studies of porphyry deposits suggest that in both the Southeast and the Northwest
Provinces the exposed (or remaining) magmas and mineralization formed within a few kilometers of
the surface. Furthermore, because mineralization and magmatism in the northwest has older
radiometric agtls than do the bulk of magmas in the southeast it is unlikely that significant post
Laramide differential uplift accounts for the more modest activity in the northwest, unless plutons
were emplaced at increasingly higher crustal levels with time. The apparent difference in magmatic
flux appears, therefore, to be real.
TIming and Duration of Laramide Magmatism
Laramide magmatism in Arizona spanned a period of 30 million years, from about 80Ma to
about SOMa, but magmatism in individual magmatic centers persisted for shorter intervals of 2 to 20
million years. Most of the available age constraints on these systems are K-Ar radiometric dates on
biotite and hornblende, although a few dates obtained by other methods exist. The dates that are
available on the systems of direct interest here are compiled in Appendix B, along with five new K
Ar age determinations on igneous rocks in the Bagdad and Diamond Joe systems obtained in this
study. Figure 2.3 summarizes the sequence of magmatic and mineralizing events in each system as
inferred from radiometric dating and field relationships.
A Generalized Description of Laramide Igneous Systems
The geology of each Laramide igneous system examined in the present study is reviewed in
the sections to follow, but there are sufficient attributes common among the systems to formulate a general description. In systems where they have not been eroded, the earliest igneous rocXs are a suite of predominantly intermediate volcanic rocks with lesser basic and acid constituents. The early volcanic rocks were succeeded by numerous intermediate to acid plutons that range in size from small batholiths many kilometers across, to small stocks a few hundred meters in size, to dike swarms. Generally, although with notable individual exceptions, the plutons become more silicic and more highly evolved with time (see Chapter 3, below). The early volcanic and intrusive magmas comprise quartz diorite, andesite, and minor basalt that yielded to later quartz monzonite, 28
AlteratlolllMlnH1lllzatlon Tombatone Rhyolite Hornblenae Andeelte Dlkee • • Rhyodecrte • auartz Lat/Ie Dikes • - Uncia Sam Porohyry Tull • Schleffelln Granodiorite Bronco liolcantca ..• - GraataMl1a Intrusives auartz LatIta Porphyry Stocks • • Joaaphlne canyon Diorite • Elephant Head Quartz Monzonlt~ Empire Stock • Corona Stack - Salero Formation Volcanics - AltaratioruMlnenlllZllllon - Produc:tmt Porphyriae - • Ruby Star Granodiorite Red Boy Rhyolite 7 • Domelne Andnrte Dlorlta Stocke - - C AlteratlOlVMlnH1lllzatlon -- .... 7--it II: Produc:tmt Porphyrlas Baboon \/olcarucs 7 • • • Lona st. Stoclc + equlvalonle e--e ~ Safford AndHlte ... AtteratlOIVMlnenllZllllon .--7-. Dacite Porphyry Pink PDflIhYrY Copper Craak Granodiorite • Glory Hole Volcanics .... - AtteratlOIVMlnerallzatJon - - TO= Uounllln Porphyry •• Ch atma Intrualve Complex • • Granite Mountain Porphyry Teacup GranodiOrite e---e MlICOonaid and Gold Basin Gds 8-4 - Rattler Granoalorlte Tortilla Quartz DiOrite ..... --- Williamson Canyon liolcanlcs ... .. Crown KIng Granodlorlto
AtteratlOIVM lnenllzatlon YaungII' Quartz Latlto Porphyry t - Oldor Quartz Lat/te Porphyry Main Gr1UIodlorito Phllse DlorItD Border Phllse •.- ciw Quartz Monzonite Porphyry -0c., Granodiorite Border Pha.e • A1teratlOlVMlnenllzatlon - Granite Porphyry Dike ,. Porphyntlc Quartz Monzonite II Quartz Monzonite Porphyry Dlklt Porphyntlc Dlorlta Dikes Blue MCKIntain Granodiorite • Bagdad Granodiorite .- South_ Granodlorlta • Porphyntlc Rhyolltlt Dlkell .... Graybacll Mounleln Tull ...- 80 75 70 65 60 55 50 AGE (M.Y')
Figure 2.3. Ages of magmatic and mineralizing events in Laramide igneous systems. Only the magmatic systems under direct examination in this study are included. The data are compiled in Appendix B. Filled circles are radiometric ages, with the larger ranges indicated by tie lines. Filled squares indicate that age is constrained relative to other units by field relationships. Filled hexagons are radiometric dates on alteration minerals related to episodes of mineralization. Arrows indicate that only a minimum age has been established. Question marks indicate uncertainty in age assignments. Typical uncertainties of the radiometric ages are ±O.5Ma to ±2.5Ma. 29
granodiorite, and granite. The porphyry alteration and CuoMo mineralization formed late in the
magmatic sequence of a given system and can usually be related to specific stock(s) or dike sets.
In the fonowing sections the geology of the individual magmatic centers is described, but
several points are necessary to clarify the discussion. Reference to rock units is usually by informal
local usage, for example the Bagdad Granodiorite and Tombstone Rhyolite, but for those units that
lack even local reference informal nam.es are assigned to facilitate the discussion. Sample locations are shown in the figures that describe the general geology in each district, but more detailed information about locations is listed in Appendix A. In the sections that describe sample distribution, only those samples that were used for geochemical analysis are listed, although for most igneous units more samples than this number were conected but were later reduced after screening by thin section petrography.
Descriptions of Individual Igneous Systems
Ray District
Geology. The Laramide igneous rocks exposed near the Ray porphyry copper deposit (Fig.
2.4A) display the greatest geochemical variety and have the longest duration of magmatic activity (15 to 20 m.y.) of the districts considered here. More detailed considerations of the Ray area may be found in Ransome (1919), Metz and Rose (1966), and Keith (1986). Banks et al. (1972) identified 13 separate intrusive rock types in this system and subdivided them into five stages: Stage I (70Ma) comprises the Tortilla Quartz Diorite and Rattler Granodiorite; Stage II (65 Ma) is represented by the Teacup Granodiorite; Stage III (61 Ma) includes Granite Mountain Porphyry; Stage IV (60 Ma) is Teapot Mountain Porphyry; Stage V «60 Ma) encompasses rhyodacite dikes and plUgs. The
Williamson Canyon Volcanics are exposed about 15km southeast of Ray, near the Christmas deposit, and erupted between 75 and 80 Ma (Koski and Cook, 1982; Keith, 1977); they predate Stage I magmas which intrude them. This unit may be represented near Ray by porphyritic hornblende andesite dikes (Banks and Kreiger, 1977) but the flows themselves, if they were present, have been removed. 30
RAY DISTRICT A IgOOloV'/ln .. Cornwall. IH2.:" .,.:..t"';'::.~~~£i@.;:t..;;.
°, 2't 3 4, Km
CHRISTMAS DISmlCT Igoo4ogy In .. KooJd .... COOl!, 1l1l2I • S.mpl. LoClllon ~:;~~..:~~\i!i,::;::~~i:.x~ B a!1Q.1 r:;!I Chlt.lm.. In\rull... ~ pluglidlk•• (64IMDI::.~::':;:,~:!~c:~!!~'X'·'~'·'~'l. ,'" QUlrtz 11111. dlk •• Iiili'lM.Cdonlld Siock Hornbl.nd' pluglidlkH '761\1.I .....~~~ •• Wlillamion ~ Volcanics (
N 0.... _ ..0 ... 5 __ r Km
Figure 2.4. General geology and sample locations in the Ray and Christmas districts. 31
Mineralization. The Ray ore body has reserves of about 650 million tons at 0.8% copper
(Cornwall, 1982; E&MJ, 1989). The deposit is localized at the intersection of north-northwest and
east-northeast trending fault zones. Most of the mineralization is hosted by Precambrian
metasedimentary rocks of the Pinal Schist, and a 400m thick diabase sill emplaced at 11ooMa.
Lesser ore occurs in Granite Mountain Porphyry and other Laramide intrusions. The distribution of
alteration and mineralization has been described by Phillips et al. (197ti) and suggests an association
between small stocks of Granite Mountain Porphyry and ore. The precise timing of mineralization
relative to igneous events remains unclear. Potassium-argon dates (Banks et at, 1972) on alteration
biotite are about 66 Ma but fIssion track dating of a hydrothermally reset apatite is 60 Ma (Banks and Stuckless, 1973). The younger date overlaps the apparent 61 Ma age of the Granite Mountain
Porphyry (Banks et al., 1972; Creasey and Kistler, 1962). Field relationships indicate that main stage mineralization formed after Stage III (Banks et al., 1972) although all five intrusive stages are cut by quartz veinlets containing copper sulfides (Banks et al., 1972). The Teapot Mountain Porphyry of
Stage IV is cut by minor copper-bearing veins but postdates main stage mineralization (E. John, pers. comm, 1989).
Samples. Samples that were analyzed from the Ray system include: 1) three from the
Tortilla Quartz Diorite, 2) two of the basic facies of the Rattler Granodiorite, 3) two of the acidic phase of the Rattler Granodiorite, 4) three of Teacup Granodiorite, 5) two from dikes cutting the
Teacup Granodiorite, 6) four samples of Granite Mountain Porphyry, 7) two samples of Teapot
Mountain Porphyry, and 8) one sample of a Stage V rhyodacite plug. The samples of Teapot
Mountain Porphyry were weathered and contained a propylitic (calcite+epidote±pyrite) alteration assemblage. The Stage V rhyodacite was strongly weathered. All other samples were fresh or had experienced only incipient weathering effects.
Christmas District
Geology. The magmatic history of the Christmas district is similar to that observed in the
Ray system. It has been described by Ransome (1919), Koski and Cook (1982), Peterson and
Swanson (1956), Willden (1964), and McCurry (1971). The Williamson Canyon volcanics and 32
associated hornblende andesite porphyry dikes (Fig. 2.4B) formed prior to Stage I at Ray. The dikes
were probably feeders for the volcanic rocks of the Williamson Canyon unit (Koski and Cook, 1982).
The MacDonald Granodiorite has K-Ar dates that make it temporally equivalent to Stage I at Ray
and drill hole intercepts suggest that it may be connected to the Granite Basin laccolith that outcrops
several kilometers to the northeast. The composite Christmas Intrusive Complex is equivalent to
Stage m at Ray. Koski and Cook (1982) divide the phases of the stock into two groups: (1) early,
veined quartz diorite, biotite granodiorite porphyry, and granodiorite, and (2) later, unveined
granodiorite porphyry and dacite porphyry. Biotite rhyodacite porphyry dikes extend laterally from
the central complex along a east-northeast trend and are related to copper mineralization four
kilometers west of the Christmas mine (Banks and Krieger, 1977). The later granodiorite porphyry
and dacite porphyry phases are only weakly mineralized. The Christmas stock is located in the
geographic center of the copper deposit. Rocks equivalent to Stage IV and V at Ray do not occur at
Christmas.
MJneJ.'1llization. Reserves of over 100 million tons at grades above 0.4 percent copper are
reported by Gilmour (1982), and production through 1980 was over 22 million tons of ore at 0.7
percent copper (Koski and Cook, 1982). Mineralization at Christmas comprises porphyry-style orcs
hosted by the Christmas Intrusive Complex and the adjacent Williamson Canyon Volcanics, and
skarn bodies that replaced Paleozoic carbonate horizons below the volcanic rocks. Porphyry CuoMo
mineralization is centered on the biotite granodiorite porphyry phase of the Christmas Intrusive
Complex and apparently preceded intrusion of the later granodiorite and dacite porphyry phases of
the complex. Radiometric ages of 64 Ma on the Christmas Intrusive Complex (Creasey and Kistler,
1962) overlap within analytical error the date of 62.5 Ma obtained on hydrothermal alteration
(McKee and Koski, 1981) associated with the porphyry deposit and support field observations
relating mineralization to the biotite granodiorite porphyry stocks and the laterally equivalent rhyodacite porphyry dikes.
Samples. The samples analyzed from the Christmas area include: 1) two samples of the basalt phase of the Williamson Canyon Volcanics, 2) one sample of a hornblende andesite porphyry 33
dike, 3) two of the MacDonald Granodiorite, 4) one of the Granite Basin laccolith, and 5) one
sample each from the biotite granodiorite porphyry and granodiorite porphyry phases of the
Christmas Intrusive Complex. Samples were fresh and unaltered except for the examples of the
Christmas Intrusive Complex that contained minor potassic and phyllic alteration assemblages and
trace amounts of sulfide minerals.
Copper Creek District
Geology. The geology and mineralization at Copper Creek has been discussed by Guthrie
and Moore (1978), Walker (1979), and Kuhn (1941). The earliest expression of Laramide
magmatism in the Copper Creek district was the Glory Hole Volcanics (>70Ma), a volcanic pile
ranging from basaltic andesite to rhyolite (Fig. 2.5A). The volcanics were intruded by the Copper
Creek Granodiorite stock (69Ma), one of three northwest-trending bodies that also includes the Dry
Camp and Sombrero Butte stocks. These were subsequently intruded by dacite porphyry, which includes an older pink porphyry phase and a younger dark porphyry. Radiometric dates on some units (Appendix B; Fig. 2.3) may be anomalously young as a result of thermal perturbation by the overlying Galiuro Volcanics that were extruded in the mid-Tertiary.
Mineralization. At the surface, mineralization is represented by breccia pipes bearing Cu
Mo mineralization (Walker, 1979). At about 700m depth these breccias yield to veins and disseminations containing bornite, chalcopyrite, and molybdenite associated with zoned porphyry copper-style alteration (Guthrie and Moore, 1978). The mineralization is associated with plugs and dikes of dark dacite porphyry (Guthrie and Moore, 1978). No reserve data are available but the deposit probably contains several tens of millions of tons at moderate copper grades (J. O. Guthrie, pers. comm., 1990).
Samples. Two samples of the more basic phases of the Glory Hole Volcanics and one of a rhyolitic phase were collected from the surface. Samples analyzed from the other units were obtained from diamond -drill core, including: 1) one of the Copper Creek Granodiorite, 2) one of the pink dacite porphyry, and 3) four of the dark dacite porphyry associated with mineralization. 34
N i SAFFORD DISTRICT (~.nlf u~on and Wit ...... ID82) • Sampla Location CJaal (ZZlMlocene baaait and myollte roBaboon Metavolcanlca (47Ma?) ~Vent breccia (Eocene) . Productlvo porphyrtel (59 !MI) • Lone star Stock and equlVllenta (67-70Ma) Sartord Andeane (t69MI) ~o Porphl"Y Copper Capolltl
Figure 2.5. General geology and sample locations In the Copper Creek and SaO'ord districts. 35
Among the samples only the pink dacite porphyry and one sample of dark dacite porphyry show
evidence of alteration and mineralization.
Safford District
Geology. Laramide igneous activity (Fig. 2.5B) commenced in this district with extrusion of
the Safford Volcanics, a succession of andesite to dacite flows, flow breccias, and tuffs. Volcanism
was followed by intrusion of several plutons with very similar ages and chemistry. Contact
metamorphic effects attributed to the Lone Star pluton have been dated at 69.8 ± 2.7 Ma (Langton
and Williams, 1982) and an overlapping age of 67.5 ± 2.6 Ma has been obtained on alteration
associated with the Sol diorite porphyry (Yarter, 1981). The San Juan pluton is another intermediate
stock that is probably equivalent to the Lone Star pluton (Blake, 1971). A second magmatic pulse
resulted in emplacement throughout the district of dike swarms and numerous, small, porphyritic
plutons that are the rocks most closely associated with CuoMo mineralization. These porphyritic rocks are collectively called the productive porphyries. The age of the porphyries is not well constrained, but secondary biotite from porphyry-associated potassic alteration zones has been dated at 60 ± 25 Ma in the Sol monzonite porphyry (Varter, 1981),59 ± 1 Ma in the San Juan quartz monzonite (Blake, 1971; Robinson and Cook, 1966), and 52.2 to 47 Ma at the Dos Pobres deposit
(Langton and Williams, 1982). The timing of formation of the Baboon Metavolcanics is uncertain and radiometric dating is inconclusive. The Baboon unit is itself mineralized by the productive porphyries (Langton and Williams, 1982), and hornblende andesite porphyry dikes, which may be feeders to these volcanic rocks, cut the Safford Volcanics. Radiometric ages of Laramide units in this district should be used cautiously because they have probably been affected by the voluminous mid-Tertiary volcanic units that overlie them here.
Mineralization. Five separate porphyry copper deposits -- Dos Pobres, Lone Star, San Juan,
Sanchez, and Sol -- occur in the greater Safford district. Dos Pobres and Lone Star were examined for this study. Copper and molybdenum mineralization forms cupolas above plugs and dike swarms of the productive porphyries and is clearly related to them. Radiometric dating is consistent with this interpretation. The Dos Pobres deposit has reserves of over 400 million tons at 0.72 percent 36
copper (Langton and Williams, 1982) and the Lone Star deposit contains 2000 million tons at 0.41
percent copper (Gilmour, 1982).
Samples. Samples were collected from the Dos Pobres and Lone Star deposits. Those that
underwent further analysis include: 1) three samples of Safford Volcanics, 2) three samples of the
Lone Star Pluton, 3) three samples of the productive porphyry at Dos Pobres, 4) two samples of
productive porphyry at Lone Star, and 5) two samples of the Baboon Metavolcanics. Sample.; were
collected from diamond drill core which reduced the effects of weathering, but the drilling
distribution dictated collection of altered and mineralized samples of the productive porphyries at
both deposits. Two samples of the Lone Star Stock were altered whereas the third was reasonably
fresh. One sample of Safford Volcanics was slightly altered and mineralized.
Crown King Stock
Geology. The Crown King stock is a large, homogenous granodiorite that intruded
Proterozoic rocks in the Bradshaw Mountains of central Arizona (no figure shown). The stock is cut
on its margins by quartz latite dikes. Ball (1982) reports a potassium-argon date of 64 Ma for the
main stage granodiorite stock.
Mluernlization. The stock lacks alteration and mineralization except for several small
breccia pipes in its northwestern quarter. The breccia pipes contain minor tonnages of 0.15 percent
Cu and 0.05 percent Mo mineralization (Ball, 1982). The stock is centered on a broad zone of base
and precious metal veins that can reach several meters in width and are similar to peripheral veins at other porphyry deposits (Lang and Eastoe, 1988). The stock lacks evidence of porphyry style alteration or mineralization.
Samples. Because previous work has shown that this stock is very homogenous geochemically (Wilkinson, pers. comm., 1987) a single, fresh sample of the Crown King Granodiorite was collected and analyzed. 37
Copper Basin District
Geology. Discussions of the geology and mineral deposits at Copper Basin include Johnson
and Lowell (1961) and Christman (1978). A granodiorite-quartz diorite-meladiorite border facies
(Fig. 2.6A) of the Copper Basin stock has been dated at 755 ± 1.6 Ma (Christman, 1978). The main
phase of the Copper Basin stock contains seriate, equigranular, and porphyritic varieties of granodiorite to quart~ monzonite and has sharp contacts with border facies rocks (Christman, 1978).
The stock is cut by an older quartz latite porphyry that is restricted to the center of the system and is associated with the formation of main stage copper ore. Younger quartz latite porphyry (72.9 ±
15Ma), although similar to and probably a late relative of the older quartz latite porphyry, intruded as copper mineralization waned.
Mineralization. Mineralization occurs within breccia bodies and as disseminations and veinlets (Johnson and Lowell, 1961). Alteration sericite gave a date of 72.6 ± 1.5 Ma by K-Ar methods (Christman, 1978). Reserves at Copper Basin are 175 million tons at 0.55 percent copper and 0.02 percent molybdenum (Gilmour, 1982).
Samples. Four samples from diamond drill core were analyzed, one each of the border facies, the main stage granodiorite, the older quartz latite porphyry, and the younger quartz latite porphyry. The sample of older quartz latite porphyry is abundantly altered and mineralized. The other three samples show evidence for minor hydrothermal effects.
Diamond Joe Stock
Geology. The Diamond Joe stock is a large (SOW exposure), concentrically zoned pluton that intruded Precambrian granitic gneiss, paraschist, and gabbro (Fig. 2.6B). An age of 72 ± 1.6Ma has been established in this study by potassium-argon techniques (see Appendix B). The geologic description is summarized from Gerla (1983) and from the personal observations of the author. The stock grades from quartz diorite/granodiorite at its margin, through porphyritic quartz monzonite, to quartz monzonite porphyry, and to leucocratic quartz monzonite and granite in its core. Contacts of these zones are gradational and dip outward from the center of the stock. Gerla (1983) concluded that the zoning resulted from in situ different ion of a single pulse of magma. 38
COPPER BASIN DISTRICT II"" Joh_ ond LDwoU, lDeI, A • Simp'. LoClUon G:]QII Inl Brt«tl plpel (73MI) r-CB11 El':2IApUtI • _Qu.u lillie porphyry (73MI) EI3 Quw monzlgd (76MI) m:::I QUIltI mOnzlgd porphyry (76MI) I/alI PrtlClmbriln qUlrtz diorite • meun I I o 200
B
• Dlmpl. LaCitian -Grlnlte dlkel ~ LlIlI_lclte dlkH I!IDD Quartz porphyry Cl Equlgranular granodiorite ~Quartz monzonite porphyry Em Precambrtln gnell' and Ichlll E!3PorphyrlUo quartz monzonite - Velnl and Faulta
Figure 2.6. General geology and sample locations in the Copper Basin and Diamond Joe districts. 39
Mineralization. An important trait of this stock is the presence of strong, widespread
hydrothermal alteration without concomitant enrichment in metals. The alteration is dominated by a
potassium feldspar-muscovite-quartz assemblage with lesser muscovite-chlorite-epidote-r.alcite-albite
potassium feldspar alteration. Biotite is rare. Alteration was accomplished by moderate salinity
fluids at 150 to 3500C. These patterns make the Diamond Joe stock similar to a porphyry copper
deposit without the metals. The very minor metal earichment that occurs does so in a few large
quartz-molydenite ± chalcopyrite veins located at the margins of the stock. Disseminated or veinlet
controlled metallization typical of porphyry copper deposits is absent.
Samples. Sample coverage of the Diamond Joe stock includes: 1) four samples of border
facies granodiorite, 2) two examples of latite-dacite dikes emanating from and equivalent to the
porphyritic quartz monzonite phase (Gerla, 1983), 3) three samples of quartz monzonite porphyry, 4)
two samples of leucocratic quartz monzonite dikes, and 5) a single sample from a quartz porphyry
(granite) dike. Alteration and mineralization was absent from all samples.
Bagdad District
Geology. The geology of the Bagdad district is reported most thoroughly by Anderson et ai.
(1955) and is summarized in Figure 2.7A. The Grayback Mountain Tuff is the earliest magmatic
product; it is a rhyodacite overall but contains up to 50 percent lithic fragments, mostly of locally
derived Precambrian rocks. Field relationships demonstrate that the tuff was followed sequeutially
by dikes and pods of rhyolite, then by stocks of granodiorite and quartz monzonite, next by diorite porphyry dikes, and fmally by quartz monzonite porphyry dikes (Anderson et ai., 1955). The granodiorite and quartz monzonite stocks lie on a N70E trend and include three phases, the Blue
Mountain, Bagdad, and Southwest stocks (informal names applied in this study). New K-Ar radiometric dates of 76.2 ± 1.7 Ma and 78.3 ± 1.8 Ma were obtained on the Blue Mountain Stock and the Southwest Stock, respectively, during this study. The stocks might expose increasingly higher levels to the southwest based on the preservation of the early tuffaceous units and the presence of deep molybdenum and copper mineralization associated with the Southwest stock (Blacet, pers. comm., 1989). Diorite porphyry dikes (dated at 75.2 ± 1.7 Ma during this study) crosscut the 40
N
• Simple locaUon [tiJ .. - O'lnlle porphyry dike (mMI?) IlUlID PorphyriUa qUlnz monzonite ( mUll ...... Cu.nz monzonite porphyry dlk81 (73-7SMI) , ...... Olorll. porphyry dlkll (75M.) \ .SoUthwelt a10ck (78M.) fm BIgd.d .tock (77M.?) c:J Blue Mountaln .tock (nMI) It "1'\ Rhyolite dlk .. (t78M.) '" O'IYb.ck Mounbln Turf (tTeM.) 1\ LIWlor !'lIk Oronll. {1400U., I" , § Old., P,ecombrlln rockl ( tlTOOM.) I ( \ I o 2 3 \ I I I ( I I km
TOMBSTONE DISTRICT (geology Inor 011.. "1', 11158) N B
• Sample Location . ':':'~".T~t-~ (i. 101_ ..._-- [3Rhyodaclte stoctc (6B-74Ma) i:... ·· ::T23;~'tJ""~"'" (, :,':: km ~Uncle Sam Tuff (74-76Ma). ':: <.''.It. ':: :", ,::::" aSchleffelin Granodiorite (76Ma)··':'·, .... , .. :( •. ';;:. ~';::: ~Bronco Volcanics (~76Ma) . "'::i1jIlP; '.' :;,' OK and pz sedimentary rocka ·.~~;lJl!,l; .f·: '.'::·~·:~·77: .... ·.. ·
Figure 2.7. General geology and sample locations in the Tombstone and Bagdad districts. 41
granodiorite/quartz monzonite stocks and are themselves cut by dikes and plugs of quartz monzonite
porphyry. The quartz monzonite porphyry dikes are commonly affected by hydrothermal alteration
and in places host minor pyrite-chalcopyrite mineralization. Two other intrusions occur in this
district but their temporal relationship to other igneous phases is unclear. The first is a porphyritic
quartz monzonite that is only exposed in the open pit mine and is the rock type associated with main
stage ore formation (B1acet, 1983). The association with mineralization of both the porphyritic
quartz monzonite and the quartz monzonite porphyry dikes suggests that they may represent the
same magmatic phase. Both are later than the Bagdad Stock but do not expose any mutual contact
relationship. The second rock type of uncertain age is a granite porphyry dike. Exposures of this
dike are also confined to the open pit mine and the only restrictions on its age are that it cuts the
porphyritic quartz monzonite and is post main stage mineralization (although it does contain minor
chalcopyrite mineralization). The Bagdad mine is located at the approximate intersection of a zone
of northeast-trending diorite porphyry dikes and a zone of northwest-trending quartz monzonite
porphyry dikes indicating a structural control to both stock emplacement and mineralization.
Mineralization. BIacet (1983) reports reserves of over 400 million tons averaging 0.46 percent copper and 0.02 percent molybdenum, yet the porphyry deposit at Bagdad remains largely undescribed. Alteration comprises both potassic and phyllic assemblages. Alteration biotite was dated by potassium argon methods at 72.7 ± 2.3 Ma by Damon and Mauger (1966). Main stage mineralization is clearly zoned about the porphyritic quartz monzonite (Blacet, 1983). Minor mineralization is associated with the granite porphyry dike; minor stockwork copper-molybdenum mineralization also occurs at the surface and at deeper levels in association with the Southwest stock.
Samples. No samples of the Grayback Mountain Tuff were collected because of the ubiquitous Precambrian lithic fragments. Samples that were analyzed from the Bagdad system include: 1) two rhyolite dikes, 2) one diorite porphyry dike, 3) five samples of Blue Mountain Stock,
4) one example of the Bagdad Granodiorite, 5) two specimens from the Southwest Stock, 6) two from the porphyritic quartz monzonite associated with ore formation, and 7) one of the granite porphyry dike. The samples of the Bagdad Granodiorite, the porphyritic quartz monzonite and the 42
granite porphyry dike were of necessity collected from the open pit mine. These samples all contain
sulfide mineralization and secondary minerals typical of potassic and phyllic alteration assemblages.
Sample preparation procedures intended to minimize the effects of such alteration for these samples
are discussed in Appendix C.
Tombstone District
Geology. The geology of the Tombstone area has been discussed by Gilluly (1956) and
Newell (1974) and is shown in Figure 2.7B. Laramide igneous events near Tombstone progressed
through: 1) extrusion of andesites with lesser, more acid phases of the Bronco Volcanics (pre-
76Ma), 2) near simultaneous emplacement of the Schieffelin Granodiorite (76Ma) and venting of
what is probably an equivalent but extrusive facies of the Schieffelin called the Uncle Sam Porphyry
Tuff (74 to 76 Ma), 3) emplacement of quartz latite porphyry dikes, hornblende andesite dikes, and a
rhyodacite stock, and 4) intrusion of the hypabyssal Tombstone Rhyolite (66Ma Marvin and Cole,
1978; Creasey et al., 1962; Marvin et al., 1973).
Mineralization. Tombstone is well known for its Pb-Zn-Mn-Ag veins and replacement deposits, but their age is not well constrained. Ore is spatially associated with hornblende andesite dikes (Newell, 1974). Sericite at the Charleston Lead mine and alteration associated with silver mineralization adjacent to the Contention dike were dated at 74.3 ± 3 Ma and 72 Ma, respectively
(Newell, 1974). The district contains no known intrusion-centered alteration or mineralization of the porphyry copper style but metal zoning patterns have been interpreted as consistent with stock associated mineralization at depth (Newell, 1974).
Samples. Samples analyzed from the Tombstone district included: 1) three of Bronco
Andesite, 2) five of Schieffelin Granodiorite, 3) four of Uncle Sam Porphyry Tuff, 4) two of the rhyodacite plug, and 5) two of Tombstone Rhyolite. None of the samples were affected by hydrothermal alteration but two of the Bronco Andesite samples and the two specimens of
Tombstone Rhyolite were weathered. 43
Sierrita District
Geology and Mineralization. The Sierrita-Esperanza system is the largest deposit within the
Pima district, a center of mining which also includes the Mission-Pima, Twin Buttes, and San Xavier
North deposits. Geologic relationships in the broader district are discussed by Cooper (1960, 1973),
Titley (1982a), Anthony and Titley (1988), West and Aiken (1982), Barter and Kelly (1982), and
Jansen (1982). The district as a whole bo~sts 1950 million tons at 0.51 percent copper and 0.03
percent molybdenum (Gilmour, 1982). Laramide magmatism in this area commenced at 68 ± 1 Ma
\vith emplacement of a group of quartz diorites along a northwest trend, and extrusion of the
Demetrie Andesite comprising andesite with lesser dacite and rhyolite. The age of the Red Boy
Rhyolite is constrained by field relationships to sometime between extrusion of the Demetrie
Andesite and intrusion of the Ruby Star Granodiorite (Anthony, 1986). The batholithic Ruby Star
Granodiorite (60 ± 3 Ma; Kelly, 1977; Shaffiqullah and Langlois, 1978) has a equigranular margin and a porphyritic interior. The stock is cut on its southwest fringe by numerous porphyritic dikes and plugs with ages between 56 and 59 Ma (Kelly, 19n; Damon, 1966; Cooper, 1973). These late stage porphyritic intrusions are associated with the base metal mineralization (West and Aiken,
1982). Alteration at Sierrita conforms to the typical porphyry copper style (Titley, 1982) and includes potassic, propylitic, and phyllic assemblages.
Samples. The samples from Sierrita discussed here were originally collected and analyzed by Anthony (1986) and the results are reported in Anthony and Titley (1988). These studies should be consulted for descriptions and locations of the samples. No additional samples were collected for this study, but some additional analytical information was obtained from the sample suite of Anthony
(1986).
Sant... Rita Mountains Suite
A suite of Laramide igneous rocks from the Santa Rita Mountains was examined by Trapp
(1987) as an example of unminera1ized Laramide rocks. Although no additional data were obtained from this suite during the present study, the existing data are referred to and included in some of the diagrams, justifying a brief description of the geology of the range. 44
Drewes (1981) is the most recent in a series of investigations that report on the geology of
the Santa Rita Mountains. Igneous rocks were emplaced from Precambrian to late Tertiary time,
but most pertinent here is the large population of Laramide igneous rocks that are scattered along
the 55km length of the Santa Ritas. These Laramide igneous rocks can be correlated reasonably
well with rocks in the Sierrita Mountains to the west (Trapp, 1987; Drewes, 1981) and are similar to
Laramide rocks in other areas of Arizona. Among the Laramide rocks that Trapp (1987) examined
were the following. The oldest rocks are andesitic to rhyodacitic flows and tuffs in the Salero
Formation. The Salero Formation has been dated at 74.3 ± 33Ma (Marvin et aI., 1973) and is stratigraphically correlative with the Demetrie Andesite in the Sierrita Mountains. A number of plutons cut the Salero Formation, including: the Empire and Corona stocks, located in the northernmost part of the range, with radiometric ages of 72 to 76Ma (Marvin et al., 1973); the
Josephine Canyon Diorite, a large, relatively basic intrusion with a K-Ar age of 68.7 ± 3Ma; and the
Elephant Head Quartz Monzonite that has an age of 70 ± 3Ma (Marvin et al., 1973). A quartz latite stock younger than the Elephant Head Quartz Monzonite but older than the youngest Laramide intrusions in this range (the Greaterville Intrusives) was also examined. The intrusions at
Greaterville have radiometric ages between 53 and 58 Ma and correlate with the productive porphyritic rocks at Sierrita. The Greaterville Intrusives are also similar in age and in their petrographic characteristics to the Helvetia stock in the north central part of the range, which is itself associated with significant base metal mineralization. In addition to the Helvetia deposit there are porphyry copper deposits at Rosemont in the central part of the range and further to the south lies the Red Mountain deposit. 45
CHAPTER 3
PETROGRAPHY, PETROLOGY, AND ANALYTICAL RESULTS
Petrography
The modal mineralogy of each sample was estimated by standard point counting techniques
and the results are listed in Appendix D. The number of points counted on a given sample varied
with grain size and ranged from 400 to 1200 per thin section. Potassium feldspar was identified by
staining with sodium cobaltinitrate. In some samples the minerals in the matrix were too fme grained for accurate, quantitative determination. For these samples the proportion and identity of
phenocrysts is given relative to groundmass.
The igneous rocks have a mineralogy that is typical of arc-related, calc-alkaline magmas. As a group, the rocks contain quartz, plagioclase, potassium feldspar, biotite, hornblende, and opaques as major mineral phases. Common accessory phases include apatite, zircon, titanite, and allanite. A pyroxene phase that displays the petrographic characteristics of augite is an important constituent of the early, relatively basic intrusions.
In the field, samples were selected to exclude hydrothermal alteration, but in order to obtain specimens of some important igneous units alteration phenomena could not be totally avoided. In all cases it was possible to avoid vein material (see Appendix C for additional information on sample preparation procedures). Minerals that were recognized as secondary alteration products include biotite, chlorite, calcite, epidote, sericite, and potassium feldspar. Sulfide minerals are also present in some samples. In only a few cases did alteration minerals constitute more than a very small amount in a given sample; therefore, in the tables that list modal composition in Appendix D the original mineralogy is given. Table 3.1 lists the samples that have been affected by hydrothermal alteration. In some samples, calcite, chlorite, and sericite represent incipient weathering effects rather than the influence of high-temperature hydrothermal fluids. 46
TABLE 3.1. Samples aft'ected by minor hydrothennal alteration.
District Altered Samples
Bagdad B3a 1, BS 1, B52, B61
Diamond Joe none
Crown King none
Copper Basin CBll, CB31, CB41
Ray R14
Christmas CH31, CH32(?)
Safford SF16, SF21, SF32, SF33, SF34
Copper Creek C31, C41, C4S
Tombstone none 47
The igneous rocks in each magmatic center typically follow a regular evolutionary sequence in their mineralogical composition. The Ray/Christmas system illustrates the sequence most clearly. The basalt phase of the Williamson Canyon Volcanics is typical of an early volcanic unit in that it contains pyroxene and plagioclase phenocrysts with lesser amounts of amphibole. The earliest stage
of intrusive activity, represented at Ray by the Tortilla Quartz Diorite, comprises pyroxene-bearing stocks with variable amphibole and biotite contents. Pyroxene is absent from subsequent intrusions
and the ferromagnesian minerals thereafter comprise amphibole and biotite in varying proportions,
either one of which may dominate the other in a given stock. The more evolved, usually younger, plutons, such as the Granite Mountain Porphyry at Ray, contain abundant biotite and either lack or
contain only minor amounts of amphibole. This pattern has been noted in each of the magmatic centers examined here, although it is developed to varying degrees of completeness. Reversals in the dominant trend do occur, an example being the Christmas Intrusive Complex which has very abundant amphibole that is inconsistent with its formation late in the magmatic sequence.
Textural variations do not show any apparent temporal progression. Porphyritic,
sUbporphyritic and non-porphyritic textures occur throughout the sequence. Among the phenocryst
phases, plagioclase is ubiquitous, and pyroxene, amphibole, biotite, and quartz variably form the
majority of the other phenocrystic phases. Opaques are also common phenocrysts but in only minor
abundance. Titanite occurs as a phenocryst but only in a few early or relatively basic intrusions, such as the border phase of the Diamond Joe stock, and the Christmas Intrusive Complex. Potassium feldspar is a phenocryst only in late stage, highly differentiated units such as the granite porphyry dike at Bagdad and the Tombstone Rhyolite.
Accessory minerals also follow patterns within the sequence. Titanite is common as both a
groundmass and a phenocryst phase in older plutons but is usually absent from younger stocks. Allanite is often observed in later plutons, although it never occurs in more than vanishingly small amounts. Zircon and apatite are common throughout the range of magma types. Monazite is reported from some Laramide intrusions in Arizona (Banks and Kreiger, 1977) but was not positively identified in this study, although its absence may be due to the difficulty of distinguishing monazite 48
from zircon and titanite in standard thin sections at the very fme grain sizes typical of the accessory
minerals in these plutons.
Two stocks have a unique mineralogy that distinguishes them from the population under
consideration here. In the Ray district, the Teacup Granodiorite forms a large stock with three main
lobes that in most places is a typical granodiorite that contains biotite with or without amphibole.
The northernmost Teacup lobe, however, also has a core that contains muscovite and garnet. These
minerals are more commonly found in the strongly peraluminous granitoids that dominated
Laramide magmatism in Arizona after about 58Ma, rather than in the met aluminous and weakly
peraluminous stocks typical of Laramide magmatism prior to 58Ma (Miller and Barton, 1990).
Bradflsh (1979) argued from textural evidence that much of the muscovite formed by subsolidus
processes, although he allowed that the relationships were nol always clear. A second example of
possibly primary igneous muscovite is the quartz monzonite porphyry and granite dike phases of the
Diamond Joe stock. The muscovite in these units can be largely imputed to deuteric or late
hydrothermal processes (Gerla, 1983). but coarse grained muscovite Oakes totally enclosed within plagioclase phenocrysts imply a primary magmatic origin for some occurrences. Stocks with these mineralogical characteristics occur elsewhere in the North American Cordillera, usually as strongly peraluminous stocks but less commonly as differentiates of metaluminous or weakly peraluminous granitoids (Miller and Barton, 1990). and this mineralogical distinctiveness should remain in mind when considering their genesis in later sections.
lUGS nomenclature (Strekeisen, 1976) indicates a range from basalt, diorite, and andesite, to granite (rtg. 3.1 and Appendix D). The early volcanic rocks are mostly andesites, with fewer examples of basalt and rhyodacite, dacite, and latite. Rhyolites are minor but occur both as associates of the early andesites and as late stage subvolcanic stocks. The population of early, pyroxene-bearing stocks comprises diorite, quartz diorite, and quartz monzodiorite. The subsequent main stage plutons are mostly quartz monzodiorites, granodiorites, monzogranites, and granites. The igneous rocks typically became more felsic as magmatism progressed in a given district but reversals in this trend are common. TOMBSTONE Rock Classification Based SAFFORD .BroncoVoicanJcs - - • Salford Volcanics a ScheIHeIin Stock on Modal Abundance • Lone Stat Stock • Uncle Sam Tuff a Prcductive Porphyries 6 Rhyodaclle Stock o Baboon Volcanics • TombsIone Rhyolite
--
COPPER CREEK IlArjDlRlSI-S
·~c.n,a.VdcMIICS • Glory Hole Volcanics - 101_,,"- a Copper Creek Stock - crena. CMMr o.n. 0 ...... • Pink Porphyry ou.::ccr.s..:ll Gdd Ban SIocU • Dark Porphyry .&Gaooo __ 0,.'-"'"'-__ _ .0.-._"",-" .t... .. "J'Cd;acUS&ad!
Figure 3.1. lUGS classification of Laramide igneous rocks by their modal proportions of quartz, alkali feldspar, and plagioclase. Data on Sierrita samples taken from Anthony (1986). ~ \!) Ouaru au.... BAGDAD Rock Classification Based DIAMOND JOE • Rhyol~e Dikes on Modal Abundance o Border Phase e Blue Mountain Stock OTransiIIonaI Phase
-- - I I ,.~
~P~0d4.e COPPER BASIN au..u au.... SIERRITA • Border Phase ODlorile e Main Phasa • Demetria Andeslte o Older Porphyry e Ruby Star Stock • Younger Porphyry o ProductJva Porphyries CROWNK/NG /\ /\ o Crown King Stock
Figure 3.1 continued. Ul o 51
Major Element Geochemistry
Methods of analysis for the major element oxides are discussed in Appendix C, and analytical results are listed in Appendix D. CIPW normative mineralogy has been calculated from
the major element data and is also listed in Appendix D. The igneous rocks are predominantly metaluminous. The aluminosity ratio, i.e., the
molecular ratio ~Cl.J/(NazO+Kz0+CaO), ranges from 0.7 to 1.95 (Fig. 3.2) but the main stage granitoids have values below 1.1. Most of the rocks with A/CNK values above 1.1 are differentiates
of main stage granitoids or have been affected by hydrothermal alteration assemblages that introduced sericite. Overall, this magmatic population falls into the metaluminous/weakly peraluminous (M/wP) classification employed by other workers (Farmer and DePaolo, 1983 and
1984; Barton, 1990; Miller and Barton, 1990). Almost none of the main stage stocks are classified as strongly peraluminous (sP), including those units that contain primary(?) muscovite. The major element data are presented in Harker diagrams for each system (Fig. 3.3), using
Si~ as the index of differentiation. The data for individual magmatic centers form coherent trends relative to Si~ although some districts behave more systematically than others. The Bagdad system has the least scatter (Fig. 3.3C) and the Ray system has the most (Fig. 3.3F). An insufficient number of samples were analyzed from some systems to clearly defme trends with differentiation, but in general as Si~ content increases the concentrations of MgO, FeO, Ff2Cl.J, CaO, Ti02, MnO, and P2 Ds decrease whereas the N~O content increases. The ~Cl.J content increases with differentiation until about 60 weight percent Si~ is reached after which it then decreases. The Kz 0 content varies more erratically than the other oxides but typically increases; at very high Si02 contents KzO may show a decrease. Total iron content decreases steadily with increasing differentiation but the ratio of ferric to ferrous iron shows considerable scatter, possibly due, in part, to the effects of oxidation of iron in surface environments that may affect even petrographically fresh rocks. The SiOz concentration generally increases as magmatism progresses in a system (Fig. 3.4) but a number of reversals to this trend imply that the position that the plutons occupy on the trends 52
2 • .2- • -..as 1.8 ..as • '5 CJ Q) '0 1.6 e strongly peraluminous (sP) -0 N 1.4 ~ + • 0 • N •• as 1.2 • Z AICNK .. 1.1 .. • • • + wetJkJy peraluminous (wP) 0 1.0 • as mstaJuminous (M) U • ~ • C'J 0 • - _N 0.8 • •.. - c( • - • 0.6 50 55 60 65 70 75 80 5102 (wt %)
Figure 3.2. Aluminosity index versus Si02 Cor Laramide Igneous rocks. 53
SAFFORD ~,7.34 • Salford And •• II. OF• .o, ~ Lon. Star SlocJc OFeO ~ Productive Par ~ Baboon Andllill ~I • l- e ° ~ ~'.j e~ ~ ~ ~ ~~. -'101 ~ ~~ I!l OAI,o, ONI.o + K,o OCaO tl ~ OK,o ONI.o OMgO ee fI ° ~ Q e fJ~ .~ Ie eO° ~. ~ 13 III eo ~. 0
0110, OMno Op,o,
~ ~ • ~ e O~ ~ ~~ ~ Ie ° e~ e eO • ~o •• Q ~ ,.~ ~ 50 60 70 50 60 70 61 SI02 (Wt 'Yo) SI02 (Wt 'Yo)
Figure 3.3. Harker variation diagrams. Symbols are used in the same order in each figure to correspond to the sequence of intrusion, and similar SiOz ranges are used to aid visual comparison of the data. Data that fall off the diagrams are shown WIth arrows and values. The intersection of solid lines visually fit through the N~O + ISO and CaO data indicates the alkali-lime index. Data for the Santa Rita Mountain and Sierrita suites were taken from Trapp (1987) and Anthony and Titley (1988). 54
7 COPPER CREEK B4 TOMBSTONE .Glory Hole Andesite rA • Bronco Andesite 6 Jt rA CFe,o, rAGlory Hole Rhyolite C"'p, (Oil Schlettelln Gd OFeO !ICopper Creek Gd o FeD !I Uncle Sam Tutt 5 I'!!Plnk Dacite Porphyry !!!I Rhyodacite Stock IiiDark Dacite Porphyry Iii Tombstone Rhyolite 4 • rA 3 ~ • rA ~iOiI 2 : e f!P ... • ~ ~ TT l- ~ !I~ ii ~ ... 0 e ~ • ~ I'!! 20 • 16 .~ • C1?i(OilrA ~ • rI1 CAI,o, !!!I CAI,o, 12 ONa,o + K,o ONap + K,o OCaO ~ ocao 8 ~ ---_. ~ ~~ -- ~ --~ 4 I- (---_. ~ ;:... 53 0 ~ _G -W 6 CK,o K.o Q ONa,o I'!! ONip )( OMgO Iii 0 5 O~o rA I'!! 4 • ~ . • t ~ •• 3 e • • ~~ ·Iitiii• e 2 • ~~ ~ " •• ~ 0 e ~ 1.5 cno, C TID, OMnO O~ Op,o, Opp, 1.0I-I- - • • 1M! ~ ~ ~ • IjI 0.5 • ~ I!! I!! ~ ~ I- ~ W !!!I • ~ : ~ia o .~ ;;" ~ ~ .. 50 60 70 80 50 60 70 80
5102 (WI %) 5102 (WI %)
Figure 3.3. Continued. 55
7 SIERRITA ~ SANTA RiTA MTN SUITE G • Dlortll Slow 8.18 • III""' Fannllllon 13 D.mlm. AndHlI. 131!tnp1r1 " COton. Slow CFep,(Tl ~ r!~ !l Red Boy Rhyoili. CFep,(T) !l J ..ophlne Cyn Dlartll r OFeO :.i e Ruby SII' aranOdlortl1 e EllPhl", Hied Q1z Monz 5 iii ull POlllhyriH IiiiII.dIe POlllhyry Siocle DallllIom Anthony (!larlat.,vUl. SlocIce 4 I- and nUey (1988) ... DalAI 110m Tripp (1907) (!J Ii 3 e~ .~ iii 2 iii e~ ~ a IJ 1 l- e e 1iIff'Q Ii] I!l (!J o. ~ ~ ~ ~ 20
16 to [;i~?I~ !l~ ". e~ (!JiillQl .. iii ~Iil CAIP, CAI,o, 12 ONa.o + K.o I!PQ ONap + KP OCeO . OCaO e .~ e B lot • e e~ ~ ~e
~ 4 jlOt a : e [ 56~ a e~ w 56 W 0 ~ Q 6 CK,o e '"' CK,o ONap e iii iii ONa.o e X 5 OMgO f} OMgO o lot • a • ®® e tia .. e • el!!! 4 a~ .~ 9~ I!lli ~ W IJ.! ~ e~ II :!l 13 PQ 3 ~ !llfJ • • aa !l 2 ~a I (j a .!) IV (j e II! 1 • ~ ~ ~ o ~4!fb ® 1.5 CTlO, C TlO, OMnO OMnO OPP. OPP. !l 1.0 ~ •• 1313 ... o. 5 ~(!J a;;J IJ IJ : e~ ·~a (j Oi e
a ~,e e· a.- ~a~ .;; ~ o ~~ !rt :J 50 60 70 80 50 60 70 80
SI02 (Wt %) SI02 (Wt %)
Figure 3.3. Continued. 56
7 DIAMOND JOE COPPER BASIN 6 • Granodiorite Border • Border Diorite ClFe,Q, !;iI Porphyritic att Monz ~ Main Phase GranodiOrite OFeO II Qtz Monz Porphyry I!! Older Qtz Lallte Por 5 !!!lQtz Monz Porphyry Dikes !!!l Younger alz Latlte Por Iii alz Porphyry Dike 4
3 2 • • .. ~ . 8~ ~ ~. Pil!l ~ tt,tle e
16 QIJI· I!! !!!ll!! Wi I!! !:I • ClAI,Q, !!!l !!!l ClAI,Q, 12 ONIlP + KP IiiiI ONa.o + K.o OCaO OCaO .
8 e" f:'-, --~ oe- 4 " 57 -~ 0 III- 6 ClK,Q !!!l ClK,o Q ONa,Q )( ONa.o 5 OMgO f!) ~Iii OMgO :) <4tt. f!)~ 4. 4 ~. 6.83 e ~ II !:Ie e ~CiiI 3 lilt • I!! -- • ~ 2 G, ee 1 • • ~ 0 .,e. 4Ito 1.5 Clno, Clno, OMnO OMnO Op,o, Op,o, 1.0
~ 0.5 IJI.. • • 'It• ~I!! ~ ~ e~~ ~ • • O+-~r-~~~~~~~~~~~... • 50 60 70 80 50 60 70 80
5102 (Wt %) 5102 (Wt %)
Figure 3.3. Continued. 57
1 BAGDAD G • Rhyolite Dilen OFep, ~ Blue Min Stock 0,.0 ~ Bagdad Stacie 5 I!! Southwnt Stacie iii Dlartte Porphyry Dike [!J POfl)hyrttfa Manz 4 ~ otz .. o arllnlte Porphyry Dike Ii 3 iii :iJ ~ e e 2 ~ ::!I ~ ~ e 1 Qi 0 0 ® 0 20
16 ~CI CI 1iI"!;I 0 OAIP, .. 12 ONap+ KP OCaO
8 •• -'#. 4
~ 0 W • Q 6 OKP ONap 0 S< 5 QMgO 0 [!I 04 • = Ii~a CIQ I) e 3 i' • 0 ~ a Ii Q 2 ~e • 1 (!) 0 0 1 OTlO, OMno QpP. 1.0 ~ ClCiI iii 0.5 ~e ~Ii G® 0 Ii Ii ~~ ~Q 0 50 60 70 80 SI02 (Wt %)
Figure 3.3. Continued. 58
of the major element diagrams corresponds more closely to Si~ content than on the timing of their
emplacement in the magmatic sequence of the system.
The alkali-lime index (Peacock, 1931) assigns most of the systems to the calc-alkaline
magma series (indices betweell 56 and 61 percent Si~) but they span a range from mildly alkaline
or alkali-calcic at Sierrita (index of 50 to 54 percent Si~) to mildly calcic at Ray (62 to 64 percent
Si~) (F'Ig.3.3). The alkali-lime index is well defmed for each suite except those from Ray and the
Santa Rita Mountains (Trapp, 1987). The plutons plot along a calc-alkaline trend on an AFM
diagram (Fig. 3.5). The magmatic systems belong to the medium- to high-K series (Figure 3.6A)
and some units have mildly alkaline affmities when total alkalies are considered (Fig. 3.6B).
Rare Earth Element Geochemistry
A Generalized Pattern of Behavior
Chondrite-normalized rare earth element (REE) profiles for each system are shown in
Figures 3.7 to 3.9. The values used to normalize the data are from Anders and Grevesse (1989). In general, each igneous system displays similar patterns of REE behavior in the course of its magmatic evolution. Although the basalts in the Williamson Canyon Volcanics have a relatively flat REE proftle, more typically the early volcanic rocks have steep, light rare earth element (LREE; La through Nd) enriched proftles, the highest overall REE abundance of the units in their system, and either lack or have small positive Eu anomalies. The subsequent population of plutons remains
LREE-enriched with La concentration 50 to 200 times the chondritic value, they have steep proflles sloping downward toward Lu, they often display upward concavity in the heavy rare earth element
(HREE; Dy through Lu) segment of their profiles, and they have Eu/Eu· values from 0.65 to about
1. (Eu· is the Eu concentration that would be anticipated by interpolating between log-normalized
Sm and Gd; Eu is the measured concentration. Therefore Eu/Eu· values above and below 1.0 represent positive and negative Eu anomalies, respectively). The rhyolites, which occur in minor volumes and occupy various temporal positions within some districts, have flat profiles but large negative Eu anomalies. 59
80
+ I I 70· + -~ I Bagdad % ;: I + I - I + -N i RqlChriatmls 0 en 60- }I I . .~
50- ... I I I 60 70 80 Radiometric Age (Ma)
Figure 3.4. Age versus SI02 In the Ray and Bagdad systems. Bars show the range in Si02 for each stage of magmatism. Fmc lines are the Bagdad district and heavy lines are the Ray/ChriStmas district. 60
FeO
tholeIItic
• • ••••e. • • o • .... I o •..• r--• •• eo '. ~ ~ '. '': ..1, :. calc-alkaline ,.. .. - .
Flgu.re 3.5. AFM ternary classification diagram. 61
6
5
4 -'#. i 3 -0 N ~ 2
1
0 10 B rhyolite trachy-dacite • • 9 • • ,- • •• • •• -?fl. 8 •• • i • -0 7 • N ~ • + 6 • • 0 N • • ns •• Z 5 ... • • • • 4 • • basalt bassltic 8Ildesite 3 50 55 60 65 70 75 80 SI02 (wt %)
Figure 3.6. Alkalinity diagrams for Laramide Igneous systems. A. K2 0 versus Si02 diagram. Lines fit to the data are ended by symbols denoting the crustal province in which they occur: squares, South Province; triangles, Northwest Province; circles, Southeast Province. B. Sum of alkalies versus Si~. 62
REE Behavior in Individual Igneous Systems
Ray/Christmas. This system displays a very regular temporal evolution in REE behavior
(Fig. 3.7A and 3.7B). The basalts in the Williamson Canyon Volcanics have small enrichments in the
LREE with (La/Yb>CN values near 2 and small positive Eu anomalies (Eu/Eu· between 1.1 and
1.15). The earliest intrusion, the Tortilla Quartz Diorite, has the highest overall REE abundance in
this system, a (La/Yb>eN value of 4 to 5, and Eu/Eu· values of 0.75 to 0.80. Progressively younger
plutons evolve to lower overall REE abundances and steeper profiles, with (La/Yb>eN values as high
as 16. The Eu anomaly steadily becomes less negative and even becomes slightly positive in the
latest intrusions; the Granite Mountain Porphyry has Eu/Eu· as high as 1.12. The MacDonald
Granodiorite has a steeper proflle and lacks the negative Eu anomaly that is characteristic of the
other intrusions emplaced around 70Ma. The temporal evolution in REE behavior parallels the
change from barren plutons (Tortilla Quartz Diorite; basic phase of the Rattler Granodiorite) to subproductive plutons (acid phase of the Rattler Granodiorite; Teacup Granodiorite) to productive plutons (Granite Mountain Porphyry, Christmas Granodiorite). The subproductive Teapot Mountain
Porphyries formed after main stage mineralization but their REE profiles are indistinguishable from the productive stocks.
Copper Creek. The andesite phase of the Glory Hole Volcanics has the highest REE abundance among the units of this district (Fig. 3.7C) and a (La/Yb>CN value of 9. The rhyolite phase has a proflle similar to the andesite but has a (La/Yb>eN value of 14 and a much lower REE abundance. Both the andesite and the rhyolite have small negative Eu anomalies (Eu/Eu· of 0.78 and 0.84). The Copper Creek Granodiorite has La and Yb concentrations similar to the Glory Hole andesite but has depressed concentrations of the middle rare earth elements (MREE; Sm to Dy) and a Eu/Eu· value of 0.68. The pink dacite porphyry has a higher LREE abundance than the other units in this system but is similar to the Copper Creek Granodiorite otherwise, particularly in its prominent negative Eu anomaly. The productive dark dacite porphyries have REE abundances only slightly lower than earlier units, with the exception of the Glory Hole Rhyolite, they have
(La/Yb>CN values of 10 to 12, and Eu/Eu· values between 0.89 and 0.94. 63
200 A CHRISTMAS B .~CynV.1a 150 ,.,.~Od (41 • a-CooIII*I 100
~ II: §! o
o~ II:
._-6,-SAFFORD__ .----..... 50
40 ~ II: §! 20 o
o~ 10 II:
RARE EARTH ELEMENTS RARE EARTH ELEMENTS
Figure 3.7. Chondrite·normalized REE diagrams for the Ray, Christmas, Copper Creek, and SalTord districts. Normalizing values from Anders and Grevesse (1989). Patterned fields used when several proflles from a given igneous unit overlap closely; the number of proflles derming a field arc indicated in the legend of the figure. 64
Safford. Andesites in the Safford Volcanics have LREE·enriched prof1les with (La/Yb)CN between 4 and 8 and small positive Eu anomalies (Fig. 3.70); their prof1les largely overlap those of
later igneous rocks. The Lone Star stock has high total REE abundance and a small negative Eu anomaly. Patterns for both the Dos Pobres and the Lone Star productive porphyries have very
depressed REE abundances, relative to other rocks in this district, and they have slightly steeper
prof1les, with (La/YbkN from 8 to 11. One profile of productive porphyry from Dos Pobres ha'l a large positive Eu anomaly (Eu/Eu· of 1.67) and a second sample has a small positive anomaly
(Eu/Eu· of 1.08). The productive porphyry at the Lone Star deposit has a small negative Eu
anomaly. A sample of the Baboon Metavolcanics has the highest REE abundance found in this system and has no Eu anomaly. A second sample of the Baboon Metavolcanics has a REE proftle so similar to the andesites in the Safford Volcanics that it may actually be a fragment of the latter
unit caught up in the breccia that predominates in the Baboon Metavolcanics.
Bagdad. The REE proflles of two samples of the early rhyolite dikes differ markedly from
each other, but have the lowest REE abundances and the largest negative Eu anomalies in this
system (Fig. 3.8A). They have (La/YbkN values of 8 and 5. Samples of the Blue Mountain Stock have the highest REE contents, steep LREE·enriched profiles with (La/YbkN values of 12 to 14, upwardly concave HREE proflles, and Eu/Eu· values between 0.71 and 0.78. The Bagdad and
Southwest Stocks are very similar to each other having (La/YbkN values of 10 to 16, upwardly concave HREE patterns, and Eu/Eu· values from 0.75 to 0.82; each unit has a slightly lower REE abundance than the Blue Mountain Stock. The profile of the diorite porphyry dike mimics the
patterns of the Blue Mountain Stock. The porphyritic quartz monzonite, the unit associated with
formation of the Bagdad porphyry copper deposit, has a lower REE abundance, particularly in the
HREE segment, than the earlier stocks and diorite porphyry dikes. The samples have (La/Yb >eN of 12 and 25 and slightly negative Eu anomalies. The subproductive granite porphyry dike has a profile
nearly identical to the porphyritic quartz monzonite with a (La/YbkN value of 20 and a Eu/Eu· value of 0.91. 65
BAGDAD DIAMOND JOE 200 • AIr/ollteDlk .. B ·.· __adI31 ""< Blut Min 8t'" 151 .. " ~eDlke 111 150 ",i DIotIIa Pot Dike 111 • 011 Mona Porphyry o II-odId BIOCII 6 011110lIl Pot Dike • _SIOCll • _PotDIke 100 6 1'ot1>hyrIIIo0ll Mo ... X 0_ Porphyry Dike 80 60
W t- ii! Q Z 0 :I: U i! U 10 0 II:
COPPER BASIN CROWN KING 200 C D • __ ad 150 ._--6 _011 LM* Pot ----• Y_ 011 LM* Pot 100 eo 60
40 ~ II: Q Z 20 :c0 u i! U 10 0 II:
RARE EARTH ELEMENTS RARE EARTH ELEMENTS
Figure 3.8. Chondrite-normalized REE diagrams fOl" the Bagdad, Diamond Joe, Coppel" Basin, and Cl"own King distdcts. For an explanation of symbols refer to Figure 3.7. 66
Diamond Joe. The granodiorite border phase has a range in (La/Yb>CN values between 10
and 16, Eu/Eu· values from 0.81 to 0.87, and upward concavity in the HREE segment (Fig. 3.8B).
The latite·dacite dikes that emanate from the transitional porphyritic quartz monzonite phase have a
similar REE profIle. The patterns of the quartz monzonite porphyry phase vary from being similar
to the granodiorite border phase, although with a very slightly lower abundance of the REE and a
somewhat more negative Eu anomaly, to a much flatter profile that has (La/Yb>CN of 6, a much
lower REE abundance, and a Eu/Eu· value of 0.98. The late stage quartz monzonite porphyry and
granite dikes are further depressed in LREE abundance, they have nearly flat patterns with
(La/Yb>CN values of 4 and I, respectively, and the Eu anomaly becomes increasingly negative. The
REE profiles of all phases of the stock hinge between Tb and Ho with most of the variability
occuring in the LREE.
Copper Basin. The diorite border phase has a (La/Yb>eN value of 12, the highest overall
REE abundance among the units in this system, and the least upward concavity in the HREE (Fig.
3.8e). The later intrusions all have very similar LREE·enrichcd profiles with (La/Yb>eN values of 8
to 20 and strongly concave upward HREE patterns. There is a slight lessening in slope from the
main phase granodiorite to the older quartz latite porphyry and finally to the younger quartz latite
porphyry; these three profiles hinge near Gd. All of the units have Eu/Eu· values between 0.95 and
1.01.
Crown King. The main phase granodiorite has a steep, LREE·enriched profile with a
(La/Yb>eN value of 19, a Eu/Eu· value of 0.94, and an upwardly concave HREE pattern (Fig.
3.80).
Tombstone. The REE profiles of the andesite phase of the Bronco Volcanics are relatively
flat with (La/Yb>CN values of 3.5 to 11, and they have negligible Eu anomalies (Fig. 3.9A). The
Schieffelin Granodiorite and the Uncle Sam Porphyry Tuff have REE profiles that are indistinguishable from each other with (La/Yb>eN values near 8 and Eu/Eu· values between 0.70 and 0.81. The profile of the rhyodacite stock is also identical to the Schieffelin Granodiorite. The 67
200 TOMBSTONE • 8rDftOD AftcIIeM 150 OTJ=:::c::!"__ m "."~_nl
60
40 W !: a: Q Z 20 0 :c u 8 10 0 a:
0SANTA __ RITA MTNS IT_tIlT! C1""'- ...... __ _- _ 6 ",,-c:,.o- ;::1. .-...... ,-__ 111
a:~ ~ o
o~ a:
RARE EARTH Et..:MENTS RARE EARTH ELEMENTS
Figure 3.9. Choodrite-oormalized REE diagrams for the Tombstone, Sierrita, and Santa Rita Mountain districts. For an explanation of symbols refer to Figure 3.7. Data from the Sierrita and Santa Rita Mountain suites taken from Anthony and Titley (1988) and Trapp (1987). Some overlapping profiles from the Santa Rita Mountain suite have been omitted for clarity. 68
youngest magma, the highly differentiated Tombstone Rhyolite, has a low overall REE abundance. a
(La/Yb>CN value near 3.5, and a Eu/Eu· value of 0.28.
Sierrita. The REE data for the Sierrita system have been taken from Anthony and Titley
(1988) and are briefly reviewed here to clarify discussions in later sections. The proflles (Fig. 3.9B) of the early diorite stocks, the Demetrie Andesite, the Ruby Star Granodiorite, and the late-stage
porphyry bodies all have similar LREE contents (120 to 160x chondritic values) but progressively
lower HREE contents; the (La/Yb>eN ratios evolve through 11, 13, 19, and 22, respectively. The
Red Boy Rhyolite has a low (La/Yb>eN value of about 3 with a deep negative Eu anomaly. Each
rock type has an upwardly concave HREE proflle and, except for the Red Boy Rhyolite, a negligible
to very small negative Eu anomaly.
Santa Rita Mountain Suite. The REE data for this suite are taken from Trapp (1987) and are also included for convenience in later discussions. The andesite member of the Salero
Formation has the highest REE concentration among the units of this suite, with exception of the
Elephant Head Quartz Monzonite, a (La/Yb>eN ratio of 7, a very small negative Eu anomaly, and a upwardly concave HREE pattern (FIg. 3.9C). The younger tuff member of the Salero Formation and the Corona, Empire, Josephine Canyon Diorite, and latite porphyry stocks all have REE proflles similar to the andesite but with slightly lower REE abundances and somewhat steeper proflles. The
Greaterville Intrusives have slightly lower REE abundances than do earlier rocks, (La/Yb >eN values of 5 to 12, and essentially no Eu anomaly. The Elephant Head Quartz Monzonite differs markedly from the other units. It is enriched in La by 160 to 350 times chondritic values, it has a very deep negative Eu anomaly, and a flat or even positively sloped HREE proflle. No other Laramide igneous rock examined in this study has a comparable pattern. 69
Sm·Nd and Rb"Sr Isotope Geochemistry
Representation or Isotopic Data
The initial isotopic ratios of rocks are usually more useful than the measured values. The initial isotopic ratio of an igneous rock is the ratio that the sample had at the time of its eruption or crystallization. Initial ratios are calculated by:
(87Sr/86Sr)lnlt = (87Sr/86Sr)meas • (87Rb/86Sr)meas(elt. 1) (1) (143Nd/144Nd)lnlt =(143 Nd/144Nd)meas' (147Sm/144Nd)meas(elt .1) (2)
The decay constants, >., used in this study are 6.54 x 1O'"12a-1 for 147 Sm and 1.42 x 1O'"11a-1 for 87 Rb.
6 The initial 87 Sr, Sr ratio is abbreviated hereafter as Sro' The parameter eNd is dermed as:
where CHUR is the chondri tic uniform reservoir which is a model of the isotopic composition of the bulk earth (Jacobsen and Wasserburg, 1984). The eNd notation is more useful than numerical values of the 143 Ndt44 Nd ratio because the numbers are more readily recognized and because its use eliminates confusion that results from the practice of different laboratories using two different
Nd isotopic ratios to correct for the effects of mass fractionation during analysis. These two normalizing techniques give consistent intralab results, but yield different 143 Ndt44 Nd ratios for present day CHUR. The calculation of eNd takes these different normalizing procedures into account and makes direct comparison of data from different laboratories possible. In this study all
Nd isotopic data were normalized to a 146Ndt44Nd value of 0.7219 which gives a present day value for CHUR of 0.512638. The eNd value of CHUR at any time in the past can be calculated by:
(4) 70
where 0.1966 is the ratio 147Sm/44Nd in the bulk earth (Jacobsen and Wasser burg, 1984). Values
of an eSr parameter can also be calculated but are not used in this study because numerical values of
the 67 Srl6Sr ratio are familiar from their common use and different normalization techniques do
not complicate the data representation. The parenthesized number following eNd indicates that a
value has been calculated for a time other than the present day; a T indicates it is calculated at the
time of formation of the unit of interest.
Neodymium model ages are parameters that can be calculated from the isotopic data but
that are independent of the age of crystallization. Model ages are, however, significantly affected by
fractionation processes in magmas, as discussed below. They essentially represent the length of time
that a rock has been separated from the mantle reservoir. Model ages are determined by calculating
at what time in the past the sample would have had the same 143 Nd/44Nd ratio as the model
mantle reservoir. Various model ages can be calculated for a rock and the model age depends upon the model of mantle evolution chosen. A TCHUR model age gives the time elapsed since a rock was separated from a mantle reservoir with a bulk earth isotopic composition. Model ages based on
CHUR are most useful when Archean age rocks may be involved. In the Precambrian, however, the mantle became LREE-depleted, its 147 Sm/44 Nd ratio increased, and it began to evolve along a non-chondritic trend toward more radiogenic compositions. Conversely, the continental crust that complements the depleted mantle began to evolve toward less radiogenic compositions. DePaolo
(1981a) developed one commonly used model for the isotopic evolution of a depleting mantle reservoir which can be described by:
eNd(at T In Ga) =O.2sr - 3T + 8.5 (5)
This model is used to calculate Nd model ages relative to a depleting mantle, TOM' For consideration of Proterozoic and younger rocks these TOM ages are probably more useful than those based on CHUR and are hereafter utilized in this study. Model ages based on Sr isotopes can also be calculated but they are not as informative as Nd model ages and are not discussed further in this study. 71
Results or Sm·Nd and Rb-8r Isotope Analyses
Fifty-two new Sm-Nd and Rb-Sr isotopic analyses were obtained from 38 intrusive and 5
extrusive Laramide igneous rocks from Arizona, and 6 examples of volcanic rocks from the exposed
Precambrian basement of Arizona. The results are listed in Appendix D. For the purposes of
compilation, and because they are discussed in many of the sections that follow, Appendix D also
lists six isotopic data from five stages of magmatism in the Sierrita system that were obtained by
Anthony and Titley (1988), and nine data points from eight igneous systems containing porphyry
copper deposits that were examined by Farmer and DePaolo (1984).
Laramide igneous rocks in Arizona form a broad array in eNdr - Sro space (Fig. 3.lOA).
The data trend from values of eNdr and Sro near 0 and 0.704, respectively, to eNdr near -14 and Sro
of 0.713. A few samples combine low eNdr with low Sro values. The data reported by Farmer and
DePaolo (1984) on mineralized igneous systems lie within this array of data but span a much
narrower range. The data arrays of individual magmatic districts generally mimics the trend of the
data as a whole but there is variability in the slope that each district dermes within the envelope.
Furthermore, districts have narrower ranges in isotopic composition than do the data overall, and the
data fields of individual magmatic centers do not overlap significantly (Fig. 3.10B). As an example,
the Bagdad system has eNdr values from -9.9 to -12.3 and, with the exception of a single value of
0.71378, a range in Sro from 0.70825 to 0.71076; the data form a comparatively flat trend (Fig.
3.10B). The Ray/Christmas system has the widest range in isotopic composition among the districts,
with eNdr values between -0.2 and -9.9 and Sro from 0.70401 to 0.70995. These data derme a
moderate to steep slope (Fig. 3.10B). Safford has the steepest slope defined by any district; the data
range from values of eNdr and Sro of +0.6 and 0.70424 to values of -8.7 and 0.70665. One note
must be made to the data on Figure 3.10. The point representing the basalt phase of the Williamson
6 Canyon Volcanics plots the measured 87 Srl Sr ratio of 0.7043 rather than the initial ratio of 0.7015.
The rock appears fresh in thin section but the very low Sro value suggests that its Rb-Sr systematics
may still have been disturbed, a common feature of basic to intermediate volcanic rocks. The actual
Sro value may still have significance and should be born in mind below. 72
o
i=' -@
A
o
~ -"0 Z III
-1
B
0.709 0.711 0.713 0.715
(87 Sri B6Sr)lnltlal
Figure 3.10. Plot of eNdT versus Sro' Upper figure shows individual data points and fields bounding the Northwest, Southeast, and South Provinces. Open hexagons are data from Farmer and DePaolo (1984) on Laramide districts hosting porphyry copper deposits (abbreviations as in Figure 2.1). Lower figure shows fields for individual magmatic centers with data points omitted. 73
Within the data array (Fig. 3.10) there is a strong correspondence between isotopic
composition and the crustal province from which the sample was obtained. Igneous rocks located in
the Northwest Province have the most negative fNdr and the highest Sro values. Rocks in the
Southeast Province have the least negative fNdr and the lowest Sro values. The South Province has
fNdr values similar to those in the southeast but the Sro values are intermediate between the
Southeast and Northwest Provinces. Lead isotope studies (Bouse and Lang, in prep; Bouse et aI.,
1990; Lang et al., 1990; and below) further substantiate and resolve these subdivisions.
There are very few obvious relationships between isotopic composition and timing of
emplacement of the magmas in a district (Fig. 3.11). The fNdr values more positive than -4.4, with
the single exception of the productive Dos Pobres pluton from the Safford district that has a fNdr
value of -3.2, belong to the early volcanic rocks. The subsequent population of intrusions has more
negative values of fNdr. The later intrusions also have the highest Sro values, whereas four of six
samples of the early volcanic units have Sro values below 0.705. Several younger intrusions, however,
also have low Sro values making the distinction less clear. There is a poorly defmed tendency for
plutons to acquire slightly more negative values of fNdr as magmatism progressed within a given
district, but many exceptions are apparent (Fig. 3.11B). The Sro values show even less tendency to
form trends with time (Fig. 3.1lA). In general, the only clear temporal change in isotopic
composition is from the early volcanic rocks to the younger plutonic rocks.
Isotopic composition does correspond to some other geochemical parameters. Higher
values of Sro and lower fNdr values correspond broadly with higher Si<\ content (Fig. 3.12). Some
individual magmatic centers have clearer trends ~an do the data overall, such as the Safford and
Sierrita districts. Lower concentrations of Sr (Cs,) correlate broadly with higher Sro values (Fig.
3.13A), as do a number of trace element ratios and concentrations (see below). No correspondence is apparent between fNdr and ~d (Fig. 3.13B).
Each Laramide igneous rock has a Proterozoic Nd model age (Table D.III in Appendix D and Fig. 3.14) utilizing either TCHUR or TOM' In the Northwest Province the TOM ages range from 1290 to 169OMa. In the South and Southeast Provinces the range is from 730 to 1350Ma (with four 74 0.714 Bagdad O. Diamond Joe • Copper Basin Sierrita 0.712 Tombatan. RaV/Chrtstmas Copper Creek C; C§; = .:!:. SaHord :s 0.710 8Qb!@ -en.. ~ CD CD -.:: 0.708 O~ It' en @t G; II - 0.706 ~ 0~" • ~1i., 0.704 -1,. • ~
lm1 0 •EB IE 122. ·111 ~ (3'.'~ -5 e I- @- , 0 1flJ· 41'• At.. "z- \jf ~ .J -10 ~~ • 0 8 ® 0 -15 80 70 60 50 Age (Ma)
Figure 3.11 EN~ and Sr0 versus age or Igneous rocks. Patterns are the same in the upper and lower figures. Squares, early volcanic rocks; circles, main stage plutons; triangles, productive stocks. 75
0 0- A EE ffi &6 II &.0 -5- ee i=' ~~.® • @) • • (J]!Jl 0 ~ -'tS ~ z... @ , A -10 • • ~~I 0 0 0 0 @ 0 -15 , ~ Crown King U o Bagdad B 0.713- ~ Diamond Joe • Copper Basin Sierrita Anthony - and Tllloy 11908, iTombstona 0.711- RaV/Chrlstmas Copper Creek cfi iii 0 += o Saflord '2 • I!.Irtv volcanla rocka eo @ • Productive alOCka o 6 .4fr. en-.. 0.709- • Bamn atacka to 0 CO (jj]J) 00:> (jJJJ) i:: IZI A ,...en ~ A CO 0.707 mm - - @~l & CD 0.705- EB -- @ ~'" A EE 0.703 I I I I I I 50 60 70 80 5102 (wt %)
Figure 3.U. eNdT and Sro versus S102• For an explanation symbols refer to Figure 3.11. 76
Nd (ppm) 40 30 20 15 10 5 0 o -.R ~==-"1I9~DI_~" QSI'., C4D..,__ 8u.In
• _ ~41'" EB l'I .....ewtmnn lE ro-CO_CtHC it:. ImrJ A o=-~!'" !Zl~ -,- -5 e :==--=.-- r= ® ~ 4'11~ 0 A ® It. 'C i =5 @~ A. -10 -c9 • e ~® @ 0 ® Oe (S)O @ (\) -15 0 0.05 0.10 0.15 Oo2( 1/Nd (ppm)
Sf (ppm) 1000 500 0.713 B ® 0.71' & ~ @ ° :5 °0 :0 0 'i:' 0.709 @ II) A. CD @ CD ~~e;0 @ i::: A $. ....II) CD 0.707 1IIlD® -- ~ tf!e. A ~ bA & e 0.705 'lit. • 74 0.703 0 0.001 0.002 0.003 0.004 0.005 1/Sr (ppm)
Figure 3.13. ENdr versus l/Nd, and Sro versus l/Sr. For an explanation of symbols refer to Figure 3.11. Hexagons are data from Farmer and DePaolo (1984) with district abbreviations as in Figure 2.1. Arrows with values are data points that lie off the diagram. 77
10.----.-----r----.-----.----.----,-----~--~
2
z'C -2 z 9 en Ib -6
-10
-14
-18+-----.-----.-----.-----r-----r-~·2a~6~----~--~ 2.0 1.5 1.0 0.5 o AGE (Ga)
Figure 3.14. ENd versus time. The heavy line plots the Nd isotope evolution of a depleting mantle (DePaolo, 1981a). Lighter lines show the evolution of Precambrian amphibolites and gneiss. The shaded arrow shows an evolution trajectory for Proterozoic crust, originally formed at 1.7SGa, with an average 147 Sm/44 Nd value of 0.115. In the histograms, the filled and ruled symbols are data from the Southeast/South Provinces and Northwest Province, respectively. The horizontal histogram plots TOM ages. The vertical histogram plots EN~ values of Laramide rocks at 65Ma. The tie lines between the ENd data and corresponding TOM values are omitted for clarity. TOM ages for the Red Boy Rhyolite at Sierrita and the Tombstone Rhyolite are > 2.0Ga and arc not shown. 78
exceptions). These model ages are mostly much younger than the 1.7 to 1.8Ga age of the
Precambrian crust in Arizona. The model ages may be affected by the patterns of fractionation that
have affected the magmas during their residence in the crust and this is now discussed further.
Model ages for igneous rocks must be interpreted with caution (Arndt and Goldstein, 1987) both because they may reflect mixtures from different reservoirs and because their ability to reflect
the age of their progenitor, if not a mixture, assumes that the 147 Smj144Nd ratio of the sample has
not changed from the value of its parent. In igneous rocks, the processes of crystal fractionation and
partial melting render the latter assumption tenuous. Because of differences in compatibility of Sm and Nd the 147 Smj144Nd ratio in magmas is often lowered relative to values in the source and this causes TOM and TCHUR ages to be minimum estimates. Less commonly the LREE behave more compatibly than the MREE or HREE and give anomalously old model ages, a clear example of which has been shown recently by Pimentel and Charnley (1991); in the present study the Tombstone and Red Boy Rhyolites exhibit this type of behavior and give TOM ages (1920 to 2170Ma) that are older than the age of the Precambrian crust in southern Arizona (1700 to 1800Ma). These complications notwithstanding, the constancy of slope of the REE profIles for main stage granitoids (Figs. 3.7 to 3.9) suggests that fractionation was sufficiently systematic to preserve relative differences in the data, even if the absolute numbers are in question.
In considering the evolution of magmas in the Sierrita system Anthony and Titley (1988) proposed that rocks with an intermediate to basic composition were important either as an intracrustal progenitor or as a crustal assimilant into subcrustally derived magmas. Five amphibolites, that were originally basic volcanic rocks, and an intermediate orthogneiss were collected from several locations in Arizona (Fig. 1.1) and their geochemistry was examined as possibly representative of intermediate and mafic constituents of the Precambrian crust. The
6 Chloride gneiss has an intermediate composition and has measured values of eNd and 87 Srt Sr of -
25.6 and 0.73965, respectively, and initial values of these parameters of 0.701 and +0.7. The
6 amphibolites have a measured range in 87 Srt Sr and tNd from 0.71'325 to 0.70347 and -6.1 to +4.2, respectively. Values of ~d(1750Ma) are between +3 and +6 and are consistent with the juvenile 79
nature postulated for the Proterozoic crust in this region. Three of the five amphibolites have SrQ
values between 0.701 and 0.7025. Impossibly low SrQ values show that the Rb·Sr systematics of the
other two amphibolites have been disturbed.
Isotopic Character of Arizona Crustal Provinces
The isotopic composition of Laramide igneous rocks has strong geographic afrIDities. The isotopic composition of areal subsets of the Laramide rocks correlates with the distribution of crustal provinces in Arizona implied by prior geologic and geochemical studies. The provincial distribution is clearly dermed by considering Nd, Sr, and Pb isotopic data together (Figs. 3.15 and 3.16). The Pb isotope data are unpublished results of a study that is being conducted in concert with this study and that is utilizing the same sample suite as here. The ranges in these Pb isotopic data are reported in
Bouse et aI. (199Ob) and Lang et aI. (1990) but the individual data values are not yet published. The data are used for the purpose of Figures 3.15 and 3.16 with permission of R. M. Bouse. The
Laramide igneous rocks in the Southeast Province have less radiogenic Pb compositions, more positive ~Nd and lower SrQ values than their counterparts in the Northwest Province. Rocks in the
South Province have Pb and Sr isotopic compositions intermediate between the Southeast and
Northwest Provinces but ~Nd values that overlap, albeit with a smaller overall range, the compositions found in the Southeast Province. The Copper Basin and Crown King districts exhibit transitional behavior in some of the plots. The isotopic subdivisions of the Arizona crust dermed here are broadly consistent with subdivisions proposed by Wooden and his coworkers (Wooden et aI., 1990; in press; Wooden and Tosdal, 1990) on the basis of the Pb isotope composition of
Precambrian rocks.
Trace and Minor Element Geochemistry
The concentrations of the large ion lithophile elements (LILE) Rb, Sr, Cs, Ba, Pb, Th, and
U, the first row transition elements (FRTE) Sc, Cr, Co, Ni, Cu, and Zn, the high field strength elements (HFSE) Y, Zr, Nb, Hf, Ta, and W, and the elements Ga, Mo, and Sb were measured by
ICP·QMS. Analytical methods are discussed in Appendix C, and the data are listed in Appendix D. 80 40
if 39 • -l 6 if ~ ~\A:~ 38 .~ C1 ... ell C1•
:l~ 15.8 clJ
15.7
if } 15.6
15.5
15.4 21
CD 20
if !-. 19 if ~ 18
17 -15 -13 -11 -9 -7 -5 -3 -1 EPSILONNdm
Figure 3.15. ENdr versus Pb isotope composition. Heavy lines outline fields for each crustal province: circles, Northwest Province; triangles, South Province; squares, Southeast Province. Filled symbols are igneous rocks barren of porphyry copper mineralization and open symbols are the productive stocks. The symbol CB denotes data from the Copper Basin district. The Pb isotope data are unpublished data used with the permission of R. M. Bouse. 81
40~------~
.Q 39 a. ~ ~ ~ 38
37 15.8 CD
15.7
if
\ 15.6 ~
15.5
15.4 21
CD
20 if ~ 19 if ~
18
17 0.703 0.705 0.707 0.709 0.711 0.713 Sro
Figure 3.16. Sro versus Pb isotope composition. Refer to Figure 3.15 for an explanation of the symbols, fields, and data sources. 82
The behavior of the trace elements with respect to differentiation is shown in Figure 3.17.
Ray and Bagdad display the most and least scatter, respectively, in the trends formed by trace
element data with increasing differentiation. The general patterns that emerge as the rocks become
more differentiated are: 1) the concentrations of Sr, Sc, Cr, Co, Ni, and Zn decrease, 2) Th, U, Pb,
Ba, Ta, Rb, Cs, and Zr increase in concentration, and 3) Ga, Nh, Hf, and Y, although they follow
coherent trends in a given district, may either increase or decrease with increasing SiOz.
Differences exist in the absolute abundance of many trace elements in the Northwest,
Southeast, and South Provinces, and these are illustrated by the relative enrichment diagrams in
Figures 3.18 and 3.19. The diagrams compare the mean trace element abundance of all rocks within
a specified, limited range in SiOz; each range corresponds to representative mineralogical and
geochemical stages in the evolution of typical Laramide igneous systems. The most basic rocks have
SiOz contents below 57 percent (note that only one sample from the Northwest Province falls into
this category, the border phase of the Copper Basin stock, and precludes an accurate comparison to the basic volcanic rocks from the South and Southeast Provinces). The group with 57 to 62 percent
SiOz includes the andesite volcanic rocks and the early pyroxene-bearing plutons. The rocks with 62 to 68 percent SiOz are the main stage monzodiorites to granodiorites that comprise over 50 percent of the suite. The subset with SiOz between 68 and 74 percent mostly comprises late stage and productive plutons. Rocks with over 74 percent Si~ are predominantly late stage aplites, rhyolites, and highly differentiated dike rocks and are not compared in the figures. The major points from the comparison are summarized schematically in Figure 3.20, and include:
1) LILE -- At all Si~ contents the LILE are most abundant in the South Province. The
Northwest Province has the lowest relative concentrations of LILE at SiOz below 62 percent
but the Southeast Province has the lowest abundance at higher silica concentrations.
2) FRTE -- The FRTE have the highest mean abundance in the Southeast Province. The
• South Province has the lowest concentration of FRTE at low Si02 but the Northwest
Province has the lowest FRTE concentration at Si02 above 62 percent. 83
20 MICHAlS' o Ta SAFFORD OTa T...... aa: 0i0MI OHI • SllIord Andellit. OHI . ONb :.i Lone Star Stoele ONb 1S --,,--.... '!! Productlv. Par ._,-- ~ Baboon Andesite 1---:=:..c;::;.., '!} GtIII"""AMte e fJ 10 ~"'::--fJ e t)a ~~ ~ t) at) ,~ ~~ ~ ~ ~ Q ee e (3 ~" --a• U e OTh OPb 9 A Y 9 Figure 3.17. Trace element concentration versus SI02.' Refer to Figure 3.3 for a description of symbols and data sources. Diagrams for the Copper Basin and Crown King districts are not plotted due to the small number of data. 84 20 TOMBSTONE oTa COPPER CREEK oTa • Bronco Andllnl OHI IIGlory Hole Andellite HI till Schllttliin Gd o ONb ~Glory Hole Rhyolite ONb '15 I!I Unci I 81m Tutt !I Rhyodldll Slock • ~C:opper Creek Gd iiil Tombltone Rhyolill ~ I!!Plnk Oaclte Porphyry ,J, 23 ~Olt1l Oaclte Porphyry 10 • ~ ~~ e· a e • aaa a t;@ 5 e ~ .... ., t> e • :i~ ~ 0 ..... ~tiIItili ~ I!I II!! Gil 30 o U 6 o U - 0 OTh ~ OTh 25 t.t. -= ~ o Pb t. OPb 37.8 t::. Y ~ ~ ~ t::. Y t> 20 tOtO g 15 ~ e ~ • ~. ~aQ A 10 ~ ~ g e :;• ~ • ~ .~ I!I 5 ~ ~ e .- I?AJtilltili a. ~ a. 0 :.: ~ liliiiJ -'i ..... 35 o So GI o So • ~39.8 U 30 ONI o NI ~ C OCs OCs III Q 'C 25- C 7S .• UB7.9 :::I J:I 20 c( .... 1: 15 - till ~ GI 10 gg ~. E l1i~ a t> ~ GI iii 5 ~~g .~ ~ ~ • • iii ~ GI 0 2 !!!! ~ U 300' .. OZn .. oZn ORb ORb ~ 250- ~ ~ OCo i oeo t::.Zr ~ t::.Zr 200' a- a- t. a- 6 1511- .A • QQ a Rf) e • ~ ~ 100- .... ~ .~ 6 <1 • a;;;J3ti11 !ll!! 50 , till ~ ~ ~~ 0 ... ~~~ ~ l1li a 500 oSr -f) o Sr := 08a 08a 2So- f) ~ 000- ee a a • ~ 7 50 rJia • t> 'III A e 5 00 ~ti11 63.1 -, 60 48.41ii11ii1 I!I 250 ~ ~~ l1li ~ 50 55 60 65 70 75 8050 55 60 65 70 75 80 5102 (wt %) 5102 (wt %) Figure 3.17. Continued. 85 20 5 ERRITA OTa SANTA RITA MTN SUITE OTa • 0I0n1l Slack. .1IMro fonnnon OHf ::iii I"..,.,.. • Cotanl Ilacta OHf ~ Demeln. Andeall. ,,~'" Cyn olonl. ONb 15 !l Rei! BoV Rhvoili. e II.Ohlnl Htld Otz Mona !!!! Ruby Slar Granodlorll. • La",. PontftYTy 810e. IilLaIa Porpnvn •• (!!ortlt..... MeIIOCh Oata 110m Anlhony 0110 Irom rroDP 1:11. and nlley (1988, 1(1 !' ... ~e '!' 471 tltfJ - 5 ~e ~! ,~~ tltl • ® f; tJ ~~ .. ~=> ! ~ • 0 I!l!ltl 'i}~;;i ~ I 30 "' ti .. :l U o U OTh OTh 25 I leo o Pb 40.5 48.9 tl 6. Y 20 e tl ~/t .. tl 15 - .. .- ~G8 10 • • !l . .!!! ~ ., .;, .. 1 ~ ~ ~~I;j~ !l => V ~ 5 !! iii !I~• .o e lIP I!l;!l~ ~ Co ~ ~•• ~~WI ~ I!l Co 0 :!I 35 o Sc o Sc • -CII t U 30 o NI o NI tJl .43.7 C OCS 1 Cs 37'~9.144 2 III 112 o 'C 25 C ,g= 20 • c( 15 . !l • C ~~ -CII a ® => e 10 .. e • • CII ~1~3 • -~e • iiJ 5 "e; III \;j :!l1Q 11~1;j '!'~ '!) i) !i: CII !! U III OZn r oZn e t-.. ORb o Rb • ~ e OCo • o Co " 1>1> 6.Zt • 6.Zt • " ~ • • e ~ ~ ~ • •... " (M ~ ~ ~ tl~ .20",1/) ® ~~ eJ tJt> PJ • 0~1;j ~ ~ I;j ~ ~ fi 1> WiI"~ WI • i!l !!!!~ ~ ee; .. 3.j ~ Q~<&~ .. '" ~ ~._. I o Sr I Sr - ~!1524 o o Ba ~ o Ba !l ~ • Q ., e ~ • e .. • e ~. ,~~ • 0 :iI e e !> Q 750 ~ Q '!J 3 :iI • III 500 • e e~ :!I ~ "' ~ -II WI 76.2 ~ 250 'tl 690,??!] ..I"! - 50 55 60 65 70 75 80 50 55 60 65 70 75 80 SI02 (wt %) SI02 (wt %) Figure 3.17. Continued. 86 20~~~~~~~------=~~ DIAMOND JOE OTa OTa • Granodiorite Border OHI Hf BAGDAD o !;iii Porphyritic atz Monz ONb ONb .R~iII1IOlkea HI atz Monz Porphyry e • f 13 elue MIn Slock ~ !!!! atz Monz Porphyry Dikes .. rlBlOdidStocIC w~ e IiiiQtz Porphyry Dike e 20.9• 31.3 a1S0UIIIwnI Slock ., :i • Dlortte Po'1l/lyly Dike 10 e (!J Porpllyrttla Qtz Monz ... o Otanlle PO'll/lyly Dike W "!) 0 0 • iii ~Q a a Q-. 0 • ~ e!!! ~~ iI 0 t'l I'J eo jl3 13 ;;ill ii~!i1 0 :t 30 o U o u ~ OTh OTh 25 o Pb o Pb ~~ t:. Y e~ t:. Y .. w 2D ~ e e ...... Il • 15 I!) 6 .. Il Il .. ~ • Il 6 Q a 10 ~ ~a .. ~e I ... I!) () !' ~ rJ Q • e ~ ~ 13 13 Co 8-. 0 13 •• ~ rJ @iJ .-~~ • .S: 35 • Q) o So o So u 30 o NI . ONI C OCs OCs RI 'tI 25 . C .a::I cC.. c Q Q) ~ a iii e ~ Q) ~ iii .. ~ ., Q) ~i tJ !I U r ..RI oZn OZn I- ORb ~ ORb OCo OCo t:.Zr rl t:.Zr ~ ~ ~ ...... e .. ~~ ~ .. .. 0 Il Il · £~ 0 • ~I!) a a w~ · la 134 • Iiil I#> -. ~ ~6 'a" ~ .. a Q!~ ::1 .. o Sr o Sr - o Ba OBa lit •• I!) · ~ ~:!) f) ~ ® • • i~ ~ (!>e 0 iiilOi • I!) (;ii- ~ -~[!] 500 I!lrJ .~!!!! • e 250 0 !! )_73 50 55 60 65 70 75 80 50 55 60 65 70 75 80 5102 (wt %) 5102 (wt %) Figure 3.17. Continued. 300%i~~~~i;------1__ 1 · 1 ".. ~;Sti;;------~ <57%SI02 67-62% SI02 80% '------.- O~ '= s. NY,; Provine •• 200% Enr1c:h.d eo% S, HW PrllVlnc.. enrtdIed 140% 100% 20% 0%1 ~i~i~il 1~'~iI.u"IIIII·" Wl.,J'o 20% 0% I II II ~ i 'u ., II II ,," II II II II " II " II " ~, ~ i • i ~ i II ~ i I 0%1 ~i·l~i·'·'·'·'J"J·'I'."""'II·'~i·'.i'i~i.1 I .20% SEProvnc:8 ·50% Emched SEPrOvnce -40% Emched I~ .100% I I , , , , , , , , I , , , , ! , , , T , T -80% I I I , , tit I I , , I , I I I , , , , , I , I ~~~~~~~~~~~~4J0~~~~~~a~ ~~~~~~J~~~~~4$0~~~~~~a~ Ordered by increasing compatibility Figure 3.18. Relative trace element endchmenls In the South and Northwest Provinces versus the Southeast Province. The data are grouped according to their SiCl.z concentration, as described in the text. OJ '-J ~ r'------, 1~,r------~ <57%51°2 57-62%51°2 400% BO% L--__ - -- - 300% S Province enriched 60% S Province Enriched 200% 40% 100% 20% ~-- 0% 11l.t1.tl.1_- ~ •• .--. c ·100% 0%1"1 -Q) HW ProYlnce Enriched .20% E -200% .c NW Province enriched _ .r:o c -300% L' ~~_L._L._L.....L....L_l._l._l._l._l._l._L_L_L_l_l_l___J___J'__'__l_J ~LI-L-L....L-l.-l~L-L-~~~-L-L-l.-l.-l~L-L-L-~~~-L-L~ W ~~~~~~J~~~~~~l~~~~~~~a~ ~~~~~~J~~~~~~l~~~~~~~a~ 100% 100% ~ 62-68%51°2 68-74%51°2 15 80% 80'% I------(j) a: S Province enriched 60% BO% S Province EnrIched 40% 20% ::IIIIUliJ.111l11t 0%1---- HW Province EnrIched -20% -20% NW'...... -40% ' , -40% LI.....I.-I_.L....L...l.-I_.L...L...l....l_LL..L-L.....ILL.L...l....l_LL..L-L-.J I ~~~~~~J~~~~~~l~~~~~~sa~ ~~~~~~J~~~~~~l~~~~~~~a~ Ordered by increasing compatibility Figure 3.19. Relative trace element enrJc:hments In the South versus the Northwest Province. The data are grouped according to their SiCl.z concentration, as described in the text. OJ OJ 89 s. • • o/~ V Q. ::0 CD :::J 0 or..... "- CD<" CJ » .... ~e:,~ C- c ~ c: O) :::::J C- e Q) O) :::::J C"l -W CD ~fq ~~ <57 57-62 62-68 68-74 Silica Range (wt %) Figure 3.20. Summary of relative enrichments of LILE, HFSE, and FRTE In the Southeast. South, and Northwest Provinces. Only relative enrichment is plotted. The same ranges of Si02 are used in this figure as were used in Figures 3.18 and 3.19. 90 3) HFSE •• The HFSE are most abundant in the South Province. Except for the Si02 range of 57 to 62 percent, the Southeast Province has the lowest mean HFSE content. The Northwest Province usually has intermediate relative concentrations of HFSE except between 57 and 62 percent SiOz where it has the lowest content. 4) Some elements behave more erratically. Between 62 and 68 percent SiOz, Cs, Co, Mn, and Ti are enriched in the South relative to the Southeast Province; these same elements arc depleted in the Northwest relative to the Southeast Province. There is very little geographic variation in Sr concentration. The trace elements that appear to distinguish the crustal provinces most consistently by their abundance are Ba, La, Rb, Zr, and Th (Fig. 3.21). Barium is high in all districts in the Northwest Province, and low in all samples from the Southeast Province. Rocks in the South Province overlap the others. The other elements are more variable, but typically the low HFSE and LILE content in the Southeast Province relative to the South Province is apparent. Most ratios between trace elements are similar among the three crustal provinces. This is especially true of ratios between two clements from within a group with similar chemical affInities, such as the LILE, FRTE, and HFSE groups, as derwed above. Ratios that do differ usually compare elements from different geochemical groups. The ratio RbjSr is higher in the South and Northwest Provinces than in the Southeast, reflecting the relative depletion of LILE in the Southeast. The ZrjTh ratio is also higher in the Northwest and South Provinces, reflecting lower HFSE in the Southeast Province. The trace element signature of individual magmatic centers can complicate the simplified geochemical distinctions between the provinces. The rocks in the Northwest Province, in some cases, diverge into two groups (Fig. 3.21B and 3.210). Bagdad has a higher concentration of LILE than other northwestern systems and, on this basis, more closely resembles the igneous systems in the South Province; the Copper Basin, Diamond Joe, and Crown King districts, although distinct in some ways, are similar to systems in the Southeast Province in others. The geochemistry of the three systems in the South Province, on the other hand, are very similar to each other. In the Southeast 300 2SO S Province * 0 2501 SE 0 --L 200 S ~ 1\ E 200 - =-- 66\ E D- rn ~150 rn B E §15O ::s C / ---- '5 0 :0100 g,oo ::s \ 0 N II: b.*'- 50 50 1[\ SEProvince I ___ *./\0 0 RI1ftlIits$ Bndsst¥ IQl::aoM:::s omiad o ' 0 60 20 /---/~ 50 SE* ~~ceb. 15 * o b. b.b. E 40- * * D- b. e- W! b.b. A rn o. B I B § 30 E 10 ::s -r: .ca a : M "---h, .c • t- SE provinc~ NW Province ~ 20 . " ~ 00 ~~ .. / ~----- b..f'< . _____ y NW Province 5 b. <0 0 () o;? /[:i.---o 1>1 o 0 0 '* ~ :!f!-' ;t t ~ 10 4 (' (' ~, C> I C__ I " S Rhyr:JI/M$/IIId eSo/ ==::r SEProvince ~omIIIed o o 400 800 1,200 1,600 400 800 1,200 1,600 Barium (ppm) Barium (ppm) Figure 3.21. Trace element variation diagrams plotting Ba versus La, Zr, Rh, and Th. In these plots the early volcanic rocks and the highly differentiated rhyolites are omitted. One or two data points that lie outside the general range have been excluded when constructing the boundaries of fields for each Province. \0 I-' 92 Province the Copper Creek system has somewhat higher LILE concentrations than the Ray, Christmas, and Safford systems, and it too has some similarity to the systems in the South Province. Differences at this smaller scale of observation tend to blur some of the larger scale geochemical distinctions between the provinces. The hygromagmatophile elements also show some differences between the provinces. These highly incompatible elements, including Ta, Nb, Th, and Hf, are not incorporated into typical fractionating phases in melts of the chemical range examined here, and their ratios should therefore reflect the ratios in their source(s). On a plot of Th-Hf-1OTa (Fig. 3.22) the data cover a broad region of the diagram. The values for rocks in the South and Northwest occupy discrete fields, but values for the Southeast province completely overlap both. Productive and barren intrusions do not differ from each other and they also span most of the overall data range. Early volcanic rocks usually have the lowest Th contents in their respective systems, and basalts in the Williamson Canyon Volcanics and andesites in the Safford Volcanics possess the lowest Th values overall, in keeping with their least evolved isotopic signature. Most of the rocks have Th concentrations higher than average upper, lower, and bulk crust (Taylor and McClennan, 1985), and higher values than were measured in Precambrian amphibolites. Some crustal rocks, e.g., the Chloride gneiss, have very high Th concentrations. 93 Dots are Productive Stocks ( l.. NW Pravlnce...... M Figure 3.22. Th·Hr·IOTa ternary diagram. Fields are shown for the Northwest, Southeast, and South Provinces. Abbreviations: M, a·MORB; PM, primitive mantle; L, average lower crust; B, average bulk aust; U, average upper crust. Compositions of aust, MORB, and mantle from Taylor and McClennan (1985). 94 CHAPTER 4 PRODUCfIVE VERSUS BARREN IGNEOUS ROCKS Major Element Behavior There is no distinct difference in major element signature between productive and barren stocks. Figure 4.1 shows that, overall, the productive stocks have concentrations of MgO, CaO, Tiqp and Na.z ° that lie in the lower half of the range of concentration defmed by Laramide igneous rocks as a whole, whereas the I<2 ° content of productive stocks covers nearly the entire range in composition. The productive stocks occupy the middle portion of the overall range in Si02 • In general, the productive stocks are often among the more differentiated members in the magmatic sequence of a given district but this is clearly not always the case, as exemplified by the Christmas Intrusive Complex and the productive stocks at Copper Creek. Neither is a minimum level of differentiation apparently necessary or attained by productive stocks. The Si02 content of productive stocks ranges from 61 weight percent in the dark dacite porphyry at Copper Creek, to 65 weight percent in the Christmas intrusive complex, to 72 weight percent in the Granite Mountain Porphyry at Ray. In general, the productive stocks have major element compositions that lie at positions appropriate to their degree of differentiation, as indicated by SiD:z content or differentiation index (refer back to Fig. 3.3), irrespective of the timing of their emplacement within the system or their productivity. Subtle differences in the major element content among the individual magmatic centers exist but they do not appear to correspond to base metal productivity. Figure 3.6A showed that the relationship between I<2 ° and Si02 content has some variation among the systems, but barren and productive systems occur in both the more and less potassic examples. The K57.5 value is near 1.8 for all but the Sierrita and Santa Rita Mountain suites which have K57.5 values of 3 and 2.5, respectively (The K57.5 value is the I<2 ° concentration at 57.5 weight percent Si02 on a conventional Harker variation diagram; trends for those systems that lack rocks with sufficiently low Si02 are lieavy line snows ovarall range In concanrrallon Ticks fTIIJ11( rna ofOOuClJVa SIOCKS 95 Small dOtS m/Ul! 0811J outslae rne general rangtt 5102/1 • :11 iilJlIIlII • T102 MgO 0 0 CaO 8 :1111 • Na20 0 00 0 .1 IIIUIilIl ! • K20 ,"1 , II"1 II I,'I! I"II : ! • •i i 2 4 6 8 10 MaJor Element Oxide Concentration (wt %) 81ml ...'." ,i • Cs 0 , Sc , I • 900+ Y • 1&11 mil • 6O()+ Co Th o· 0 0 0 Pb- • lillill : I I • ¢ 0 0 La • ' I III III I 8 NI 1~0+ i i i i i 0 10 20 30 40 50 81 ;::1 Ii I I :. Q 0 3580+ znj , Zr • I 11:1 II"Ii II :: • Rb • i HI I I ' I i i , , i • i 0 50 100 150 200 250 300 1111 1111 0 sr] • II "' • 8a • I III : I II .. , i 0 250 500 750 1000 1250 1500 Trace Element Concentration (ppm) Figure 4.1. Comparison of major and trace element compositions of productive and barren igneous rocks. The heavy line terminated with filled circles indicates the overall compositional range for Laramide igneous rocks. The open circles indicate data that do not lie within the range defined by the majority of samples; arrows with values indicate data that falloff the figure. Tick marks along the heavy lines indentify the data values for productive stocks. Note that four different concentration ranges are specified for different groups of elements. 96 extrapolated). Since the Sierrita system is productive and the Santa Rita suite might be called barren, it is unlikely that their difference from the other systems bears upon their productivity. Trace Element Behavior The abundance of some trace elements differs between productive/subproductive and barren intrusions (Figs. 4.1 and 4.2). The productive stocks are depleted, as a group, in Mn and Y relative to barren intrusions. A parameter representing the HFSE as a group, summing Ta, Nb, Zr, and Hf, also shows a strong depletion in the population of productive and sub productive stocks. Similar behavior for Y and Mn was noted by Baldwin and Pearce (1982) in productive and barren intrusions in Chile. The geochemical behavior of Y, the HREE, and the HFSE is similar, particularly for the ftrst two, and their mutual depletion in the productive stocks is consistent. They will be discussed in more detail below. Rare Earth Element Behavior The REE proflles of productive plutons differ consistently both from other, barren intrusions from the productive system itself and from nonproductive stocks in completely barren systems. Productive plutons have steeper REE proflles, lower total REE abundance, and less negative to even positive Eu anomalies when compared to their barren counterparts (Fig. 4.3). The LREE are somewhat less depressed in abundance (Fig. 4.4A) than are the HREE (Fig. 4.4B). Subproductive stocks often exhibit transitional proflles, as was demonstrated in a previous section for the Ray and Christmas districts (Fig 3.7 A and B). The MacDonald stock, in the Christmas district, is the only case in which a rock thought to be a barren, older pluton has REE proflles like those from productive stocks. This exception may result from an inadequate understanding of igneous relationships at Christmas. Two K-Ar dates on hornblende from the MacDonald stock place it among the 70Ma group of intrusions, but hornblende dates in this district are often anomalously old (Banks et al., 1972). The age of the Christmas Intrusive Complex is constrained only by a single K-Ar date on biotite from samples affected by hydrothermal alteration. Radiometric dating may, therefore, be unreliable. The many geochemical 97 500 00 0 0 0 0 0 0 0 00 Barren o oOJ 0 0 400- 0 -e CO 00 Co Co 0 00 -w (/) 0 u. l8Ioogo~ 300- i o 0 0 o. ~ 0 0 0 Productive 0 200- ~O 0 • • productive ~ = subproductlve • 0 0= barren I I I I U u 1000- 0 0 BARREN 00 0 0 750- 0 -E 0 0 Co 0 Co Figure 4.%. Trace elements that dJstinguish produc:t1ve and barren igneous rocks. Each figure plots barren, subproductive, and productive rocks. In the upper figure, EHFSE is the sum of Zr + lONb + lOHf + SOTa, each in ppm. 98 Barren and ProduC!Jve Stocu In Arizona 200 150 100 80 60 40 W t: a: a Z 20 0 U~ 0 a: OBmen Bllm.lrI! Granodiorite Batholith eProduC!Jv. Younger Porphyry Santa ROil Porphyry Copper System. Peru PRChina 200 fa_tom La OIl. 191!S1 (.... """' ZlWIn """ "'mono. 10091 160 60 40 ~ a: az 20 0 :c u i2 u 10 0 a: , .. o Blrren flablya Batholith o Blrren Vlrlbambl Batholith e ProduC!Jve Wuahln Monzongranlte Porphyry e ProduC!Jve Santi Roa. o Barren Blollte Grenlte BathOlith La C. Nd 5m Eu Gd Tb Ho Er Tm Vb Lu La ca Nd Sm Eu Gd Tb Ho Er Tm Vb Lu RARE EARTH ELEMENTS RARE EARTH ELEMENTS Figure 4.3. Chondrite normalized REE profiles of barren Ilnd productive igneous rocks. Figure 4.3A illustrates the fields defined by all units in the productive and barren subgroups. Figures B, C, and D compare REE proflles of productive and barren stocks from other porphyry copper mineralized districts; the data sources are from the literature, as indicated in each diagram. 99 !II. proauctive 200- A o 18l. SUboraouctlve O· blmtn o EIJIty voteanlC roCICS and E 175- o ff'lyOlnes ommea 0. BARREN o 0. 150- e- o 0 Co '0 en <2, O~ M + 125- 'tJ dJ . 11~~------=------~B ~. proauc:uv. ' E • IUtlfX'DcSUctlvl a. 10- O • blINn a. a &tty KlIcIInIc t'DCJIS ana - 9- A rtfyfJIita ommea ~ a + 8- 0. 0 a .c >- BARREN '() 0 (l + 7- rSJ 0 o e o I- 6- + OOg o .. 5- Cct> W o 0 + 4- o o f) 0·0 0 __ ::c cr Figure 4.4. ELREE and EHREE versus Eu/Eu" ror productive and barren Igneous rocks. The diagram compares only the main stage granitoid rocks from Laramide systems; the data from early volcanic rocks and the highly differentiated rhyolites have been omitted. 100 and mineralogical similarities between these two igneous units implies that a closer genetic connection may exist between them than has been previously thought. The differing REE behavior of productive versus barren stocks in Arizona might reflect a more generally applicable discriminating factor. Support for this assertion is found in the few published studies that compare productive and barren stocks in magmatic systems from porphyry mineralized districts elsewhere (Fig. 4.3). Figure 4.3 compares: 1) the barren Yarabamba batholith with the productive Santa Rosa Porphyry in Peru (LeBe~ 1985), 2) a barren biotite granite to a productive monzongranite stock from the Wushan deposit in the Peoples Republic of China (Zhitian and Kezbang, 1989), and 3) the barren Bismark Batholith with the productive younger porphyries from the Yandera deposit, Papua-New Guinea (Lang and Titley, unpub. data). The absolute REE concentrations vary from one area to another, just as they do in the Laramide systems in Arizona, but the differences in REE profUes between productive and barren plutons show very similar relative differences that parallel REE behavior in igneous systems in Arizona. Oxidation State Several studies have demonstrated that productive magmas in porphyry copper systems are strongly oxidizing and can even approach the hematite-magnetite buffer (Hess, 1986). In those studies which made a comparison, barren stocks have been found to be relatively less oxidizing (Mason and MacDonald, 1978). The only data generated in this study which relates to the oxidation state of the magmas is the ratio of ferrous to ferric iron. Figure 4.5 shows that this ratio does not distinguish between barren and productive stocks. Further studies of the crystal chemistry of igneous ferromagnesian minerals in barren stocks, after the methods employed by Hess (1986) in the Sierrita system, are needed to assess whether any systematic differences exist in the oxidation state of the magmas in Arizona. Nd and Sr Isotope Behavior As a whole, the population of productive stocks cannot yet be distinguished from their barren counterparts by their Sm-Nd or Rb-Sr isotopic signatures. The Nd and Sr isotope 101 6 0 0 5 0 4 0 0 0 00 -'#. 0 i 0 0 ... 3 -0 Q)N U. 2 1 • • productive I8l • 8ubproductlve o o • barren O~~----T------~------~------~------r-----~ o 1 2 3 4 5 6 FeO (wt %) Figure 4.5. Relationsblp between Fe20 3 and FeO In productive and barren Igneous rocks. 102 composition of the productive plutons as a group spans most of the range displayed by Laramide magmas overall (Fig. 4.6). The productive plutons tend to lie toward the lower fNdr and higher Src end of the isotopic array for a given magmatic center (Fig. 3.10), but there are several important exceptions to this pattern, such as the Christmas stock and the productive porphyry at Dos Pobres which have among the least negative fNdr values, -6.5 and -3.2, and very low Sro values, 0.704 and 0.7055, respectively. Lead isotope data show a similar relationship between productive and barren stocks, and are also unable to distinguish between the populations (Bouse, pers. comm., 1991). The segregation of individual districts into restricted fields on a ENd - SCc diagram probably does not reflect distinctions between barren and productive igneous systems. In part, this is because the barren systems are not consistently displaced from productive centers (the difficulty of identifying systems and their prodUctivity notwithstanding). The barren Diamond Joe system has very negative fNdr values and high SCc' the Crown King stock has low ENdr and SCa in the middle of the range of the systems, and the barren(?) Tombstone system lies at the upper margin of the data array with much less negative fNdr values and only moderately radiogenic SCa (FIg. 4.6). 103 • Productive 0 0 o Barren 0 0 o. -4 • (80 0 0 • 0 t- .8r56 • @)- -8 -"0 ~. Jt Z 00 0 '" 0 0 0 0 Crown King tfJ 0 DIstrict •• 0 D/~~ DIstrict -16 0.703 0.705 0.707 0.709 0.711 0.713 0.715 (87 SrI 86Sr)lnitlal Figure 4.6. Relationship between EN~ and Sr9. in productive and barren igneous rocks. The fields for the barren igneous systems at Tombstone. croWD King, and Diamond Joe are indicated. 104 CHAPTERS DISCUSSION Introduction Magmas generated in continental arc settings are products of a complex interplay of source and process (see, e.g., the recent summary by Wilson (1989». Arc magmas form a continuum from pure mantle melts, through mixtures of crust with primary mantle melts, to products of pure crustal anatexis. Each potential contributing reservoir, whether it is in the mantle or the crust, may possess considerable geochemical heterogeneity, which is imparted to the magmas. Irrespective of their original parentage, the magmas ascend through a thick, old, and lithogically and geochemically heterogenous continental crust which imparts, through assimilation, mixing, and chemical exchange processes, aspects of its isotopic and elemental geochemistry to the original melts. Most arc magmas experience, usually in chambers in the middle to upper crust, crystal fractionation processes that further alter their geochemistry, although isotopic composition is not affected. Finally, upper crustal processes operating at near- or subsolidus conditions may effect transfers of chemical and isotopic components between the intrusion and its wall rock, adding a fmal complicating imprint to the igneous rocks. Any effort to gain insight into the petrogenetic evolution of arc magmas is further complicated by an imprecise knowledge of the geochemical composition of potential source regions and contaminants, the broad ranges in the available data on mineral-melt partition coefficients, and the uncertain physical and chemical relationship between individual igneous units in a magmatic system. As the data are discussed below, the reader must remain conscious of these limitations imposed upon interpretations. In the following discussion, the characteristics of the reservoirs that might have contributed to Laramide magmas are considered fIrst, as a prelude to a discussion of the provinciality in isotopic 105 composition and the sources of the magmas. More detailed consideration is then given to the processes that might have effected the patterns of isotope and trace element geochemistry that are observed. Finally, a model for Laramide magmagenesis and metallogenesis is described and its practicality is assessed. The following discussion can be prefaced by stating here two of the more important conclusions of the study regarding Laramide magmas: 1) Precambrian continental crust played a dominant role in their petrogenetic history, and 2) certain orderly geochemical behavior reflects the action of a systematic process upon the magmas themselves or on their heterogenous crustal source region. Isotopic Evidence for Components of Laramide Magmas Nature of the Lower Crust of Arizona The close alliance between Laramide magmas and the Precambrian continental crust, which will be demonstrated below, necessitates a brief review of the current knowledge about the composition of the crust in Arizona. Although understanding of specific geologic and geochemical attributes of the lower crust remains limited, some general information about its structure, geochemistry, and rock types have been inferred from geophysical studies, the geochemistry of intrusions that are thOUght to have been derived from the lower crust, and basalt-hosted xenoliths that last equilibrated at lower crustal poT conditions. Additional information derives from studies of exposed Precambrian basement rocks that formed during the principal crust-forming event in this region. The evidence discussed below suggests that the lower crust in this region is heterolithic with predominantly basic compositions and, although the lower crust is geochemically quite variable (eNd ranges from +8 to -13), it is somewhat less so than outcropping Precambrian basement rocks (c:Nd range from +13 to -25). Geopbysical Studies. Seismic studies suggest that the lower crust in western Arizona is compositionally layered, that wholesale mafic underplating either has not occurred or is no longer apparent, and that the rocks do not have a strongly basic composition (Johnson and Smithson, 1990). The upper 15km of crust in the Transition Zone in northwestern Arizona is dominated by the Bagdad Reflection Sequence, a regionally extensive entity which probably comprises widespread, 106 acidic, Proterozoic intrusions in which the reflectors may be basic sills; the crust assumes a different character, of uncertain composition, below 18km (Clayton, 1991). The crust in southeastern Arizona also lacks evidence for significant underplating, and is somewhat less prominently layered than crust beneath northwestern Arizona. Geophysical data (McCarthy et al., 1990) are consistent with an intermediate composition (diorite) for the middle crust, and intermediate to basic compositions (gabbro, amphibolite, mafic granulite) in the lower crust. Lower Crustal Xenoliths. Amphibolites and basic to acidic granulites derived from both ig neous and sedimentary parents characterize the xenolith population that occurs in alkaline volcanic centers in Arizona, New Mexico, southeastern California, and northern Mexico (Esperanca et aI., 1988; Ruiz et aI., 1988; Nealey et aI., 1990; Manchester et aI., 1990; Hanchar et aI., 1990; Cameron et al., 1990; Warren et aI., 1978, Kempton et a~ 1990, Arculus et al., 1987, among others). The xenoliths last equilibrated at pressures of 8 to 13 kbar and temperatures of 600 to 95cf C, within the range of conditions expected in the lower crust. Overall, basic compositions are more common than acidic, and igneous progenitors are more common than sedimentary. Some xenoliths are restites of partial melting events (Kempton et aI., 1990; Nealey et al., 1990). Isotopic data imply that most xenoliths are Precambrian rocks, although their complex poT history makes interpretation of their true age difficult. The isotope and trace element geochemistry of lower crustal xenoliths is quite variable (see references listed above). Their eNd values range from -13 to +8 (Fig. 5.1). Remarkably, a range of 20 e units occurs in xenoliths from the Geronimo Volcanic Field alone (Kempton et al., 1990), demonstrating that the full range of isotopic heterogeneity may exist even in very narrow columns of crust. The trace element composition varies from LILE-depleted to relatively undepleted compositions. Many xenoliths are crosscut by veins that contain hydrous mineral phases, principally amphibole and phlogopite, that also formed under PoT conditions of the lower crust. The veining has an uncertain temporal relationship to its host (Esperanca et al., 1988) but it attests to the presence and mobility of fluids in the lower crust. 107 • MlIllIsl/C1/menwv progflllltor Lower Crultllli Xenoliths o Matl/igflflOUS progenItOr (Arizona, Northern Mexico, B.2 1.B I[l I i q, J" ~ tll50 to t 750MIIlntruSlOllS AI'I~&"I~' Expand Precambrian Balement • t400MII IntruSlOlls o 1700 10 IBOOMIlIIOiCIln/C lind sl/C1lmlln/8ly roc/a (Arizona, Colorado, New Mexico, :~~:~~I-'-""'~ ---..A....,...... ~:..4IA-BWIL.! WLcq~a-,.w....u..crn~-l...R.L...L...Lm--,.L.L..,L~...1.- 1 -.:..."..L-! .;,..,L.,R • SoutII Provrnce Strongly PeralUminous laramide ~ NOfUIWeSr Provrf1C8 o SoutheBSt Provrnce Plutonl (Arizona. Colorado, Juraulc Igneous Rocka (Southern ArizoQ. SE California, q til SoutII Province • NOItIIwest Provrf1C8 MatalumlnouSlWeakly Peraluminous o SourtteIIst Provrf1C8 laramide Igneous Rocks (Arizona, I!I VoIcInIc roc/a from SE Provrnce -20 -15 -10 -5 o 5 ENd Figure 5.1. Compilation or ENd values of Precambrian crust, lower crustal xenoliths, and Mesozoic Igneous rocks in the SouthwesL ENd values are calculated at time of formation for Laramide and Jurassic stocks, at 70Ma for Precambrian samples, and variably at 70Ma, 30Ma and OMa for xenoliths. The data are from Arizona, New Mexico. northern Mexico, Colorado. and southeastern California. Data on lower crustal xenoliths do not include occurrences in the Colorado Plateau. The data on exposed, 1700 to 1800Ma basement rocks includes basic and acidic volcanic rocks. sedimentary rocks, and volcanically-derived sedimentary strata. Five samples of Precambrian tholeiitic basalt from New Mexico with ENd(70Ma) values of 11 to 13 are omitted. Data are compiled from Ruiz et aI. (1988). Kempton et aI. (1990), Esperanca et aI. (1988), Arculus et aI. (1987). Farmer and DePaolo (1984, 1987), Nelson and DePaolo (1985), Anthony and Titley (1988), Asmeron et aI. (1991), DePaolo (1981b), and this study. 108 Exposed Precambrian Basement Rocks. Precambrian rocks in southwestern North America have a wide range in isotopic composition. The available data on Nd isotopes in exposed Precambrian rocks in Arizona (this study; Farmer and DePaolo, 1984), Colorado (DePaolo, 1981a; Nelson and DePaolo, 1985), and New Mexico (DePaolo, 1981a) are compiled in Figure 5.1. The overall range in ~d (70Ma) is from -25 to +13; most basic volcanic rocks have values between +5 and -5, intrusions and volcanic rocks with intermediate to acidic compositions have values between -5 and -20, and 1400Ma granitoids have, with one exception near 0, a range from -12 to -23. Strontium isotope ratios are less often reported but also have very wide ranges. The range in isotopic composition of Precambrian basement is probably representative of rocks in the upper and middle crust. The applicability of this data to the lower crust remains equivocal; Precambrian basement rocks and lower crustal xenoliths have similar upper limits in eNd values but the exposed rocks range to more negative e values. Isotopic Reservoirs That Contributed to Laramide Magmas Several reservoirs may have contributed to the fmal isotopic composition of Laramide magmas. The preponderance of negative eNdr and high Sro values rules out a derivation solely from the mantle. The large range in isotopic composition most logically results either from the variable incorporation of Precambrian crust into mantle-derived melts, or from anatexis of Precambrian crust with a wide range in isotopic composition. Modeling is complicated by heterogeneity in the mantle (Zindler and Hart, 1986; Farmer et ai, 1989; Menzies, 1989) and the continental crust (Fig. 5.1) which precludes assumptions of specific endmembers with narrow ranges in isotopic composition. In this light, any plausible scenario for the genesis and evolution of Laramide magmas must consider a broad range of potential crustal and subcrustal contributors. The data array formed by eNdr and Sro values (Fig. 5.2) probably reflects participation by reservoirs with: 1) high eNd and low 87 Sr1 6 Sr, 2) low eNd and high 87 Sr16Sr, and 3) low eNd and low 87Sr16Sr; each of these is discussed below. High eNd - Low 87Sr/86Sr Reservoir. Three possibilities exist for this reservoir: crustal rocks, depleted asthenospheric mantle, and 'enriched' (or less depleted) subcontinental lithospheric mantle. 109 20~--D~M~MU------~ D 10 PREMA HIMU D Lower Crustal .. : ...... - Xenoliths '" ~ 01r--~--~~----~~~------~ Z ...... Precambrian w ...... #" Basement '0, •••••••••••••••••• . ' ..... ·10 ..... • • 0'0 •• ..... • EMI ". .... • ...... '" '" -O't • .... "" ...... ·20 .... 0.7 0.705 0.71 0.715 0.72 Sro Figure 5.2. eNd:r versus SrQ.,.plot with Isotopic reservoirs Indicated. The fields for mantle reseroirs labeled DMM, PR~MA, HIMU, EMI, and EMIl are from Zindler and Hart (1986). 110 Intracrustal candidates include young, juvenile material, or Proterozoic crust that maintained high 147Smj144Nd and low 87 Rbf8sr ratios. No significant additions of material younger than that formed during the principal crust-generating event at 1.7 to 1.8 Ga are currently recognized in this region, although southern Arizona was affected by late Triassic to Jurassic arc magmatism and the presence of subduction-related, basic magmas injected into the deeper crust cannot be completely dismissed. Precambrian amphibolites and basic granulites with high eNd and low 87 Sr f8 Sr are common in lower crustal xenoliths and in outcropping Precambrian rocks. Such isotopic signatures can be readily preserved in crustal rocks. A rock originally extracted from depleted mantle at 1.8Ga with a initial eNd value of +4.0 would need a 147Smj144Nd ratio of 0.18 to obtain a eNd(70Ma) value of +0.5 (the highest eNdr value obtained from a Laramide rock in this study; see Figure 5.3). Similarly, a rock with a 87 Srf6Sr(I800Ma) value of 0.701 to 0.703 requires a time-integrated 87Rbf6sr ratio of about 0.04 to evolve to a 87 Srf8Sr(70Ma) ratio of 0.704. High values of 147 Smj144Nd and low values of87 Rbf8s r are typical ofrocks with basic compositions and, indeed, lower crustal xenoliths with such compositions are common. Two types of mantle are possible repositories for high eNd and low 87 Sr f6 Sr material. One such reservoir is a depleted asthenospheric mantle; its presence in the arc environment and the importance of its contribution to arc magmatism is widely accepted. It might plausibly be represented by depleted MORB source or the DMM and PREMA components of Zindler and Hart (1986). In a subduction setting, depleted asthenosphere would reside in the mantle wedge and would have a range of eNd values from +6 to + 12 and 87 Srf6Sr values near or below 0.7035 (Fig. 5.3). A second, and more controversial, mantle candidate is 'enriched' (or less-depleted) subcontinental lithospheric mantle. Higher NdjSm and RbjSr ratios in this enriched reservoir would yield lower eNd and higher 87 Srf6Sr values than depleted asthenospheric mantle. If present, this material might physically occur as a keel of material attached to the base of the crust; it may have formed as a consequence of volatile fluxing accompanying subduction events during the Precambrian (Farmer, 1988). Contributions from enriched mantle have been proposed for late Tertiary volcanic rocks in southern Nevada (Farmer, 1988; Farmer et al., 1989) and elsewhere in the North American III Cordillera (Menzies, 1989; Cooper and Hart, 1990). The conditions which may have prevailed in the Laramide, i.e., a shallowing subduction angle of the descending slab that caused magmatic centers to migrate inland (Coney and Reynolds, 19T1), may have precluded a significant role for subcontinental lithospheric mantle in this region. It would be difficult for significant amounts of such a component, if present initially, to remain attached to the continental crust during passage of a flat lying slab in the Laramide. On similar grounds, Barton (1990) suggested that the enriched mantle component proposed by Farmer (1988) to be present in basalts in the southern Great Basin may be more plausibly accounted for by an influx of geochemically appropriate material from beneath Precambrian crust located farther to the east as the angle of slab descent increased markedly in middle Tertiary time and the mantle wedge was reestablished. The nature and origin of enriched mantle components remains, therefore, strongly debated, and the role that it plays in magmagenesis, its distribution, its geochemical composition, and its degree of heterogeneity are equally controversial. Low ENd - High B7Sr/BBSr Reservoir. This isotopic composition is typical of Precambrian continental crust. In a study of lower crustal xenoliths from Camp Creek, in central Arizona, Esperanca et aI. (1988) found amphibolites and granulites with ENd values as low as -9 and Sr(30Ma) values as high as 0.708. At Chino Valley, in northwestern Arizona, a suite of xenoliths similar to those at Camp Creek have ENd values as low as -12.5 and Src as high as 0.707 (Arculus et aI., 1987). Paragneiss xenoliths from northern Mexico (Ruiz et aI., 1988) have ENd near -13 and 87 Sr/6 Sr values of 0.730 or higher. In the Geronimo Volcanic Field in southeastern Arizona xenoliths of variable parentage have a wide range in isotopic composition (Kempton et aI., 1990) that extends to low ENd and high 87 Sr/8Sr. A rock that was juvenile crust at 1.8Ga with a 87 Sr/6Sr(1800Ma) between 0.701 and 0.703 would need a time-integrated 87Rb/8Sr ratio between 0.15 and 0.35 to generate a 87 Sr/6Sr(70Ma) value of 0.707 to 0.710. Similarly, a rock with an ENd(1800Ma) of +4.0 would need a 147 Smt44 Nd ratio of 0.115 to achieve a value of -IS in the Laramide. These ratios are reasonable for rocks of intermediate composition and are within the range measured on lower crustal xenoliths. 112 Some limitations can be inferred for the isotopic composition of the crustal component. No metaluminous or weakly peraluminous igneous rocks in southeastern or southern Arizona have Sra values higher than 0.710 or eNdr values more negative than -10. The minimum values for northwestern Arizona are 0.714 and -14. These may be limiting levels for Laramide magmas in their respective provinces (cf. Anthony and TitIey, 1988). Anthony and TitIey (1988) noted that metaluminous, calc-alkaline granitoids hosted within Proterozoic crust elsewhere in the world commonly yield minimum eNd values of -9 and maximum Sra values of 0.712; this may reflect a fundamental compositional feature of Proterozoic crustal sources for calc-alkaline magmas in general. Therefore, a lower crustal source or contribution to these magmas is probably more important than contributions from the upper and middle crust which has lower eNd and higher 87 Sr /6 Sr ratios that are reflected in the isotopic composition of strongly peraluminous granitoids (Farmer and DePaolo, 1984) and exposed Precambrian basement. Low ENd· Low 87Sr/86Sr Endmember. This isotopic signature can readily develop in lower crustal rocks. Lead isotope studies (Wooden et al., 1988) demonstrate that the lower crust in the Mohave Province (western Arizona and southeastern California) was depleted in U relative to Pb and Th shortly after its formation in the Proterozoic, probably as a consequence of high grade metamorphism. In a similar fashion, metamorphism can remove Rb in preference to Sr, thereby allowing an initially low 87Sr/6Sr ratio to persist. In contrast, the Sm/Nd ratio should not be appreciably affected, even at high metamOl-phic grades, thereby allowing old crustal rocks to evolve to eNd values commensurate with their initial 147 Sm/44 Nd ratio. Geographic Variations in the Isotopic Composition of Laramide Magmas. One of the most noteworthy features of the isotopic data is that Laramide rocks in the Northwest Province of Arizona have a range of eNdr values (-9.6 to -14.5) that is distinct from that of Laramide rocks in the South and Southeast Provinces of Arizona (+0.6 to -9.9) (Fig. 43). Less pronounced differences are also evident in Sra values. Several causes for these geographic distinctions may be postulated. 113 Crust-Mantle Mixing If the plutons represent mixtures of mantle and crustal melts, or if mantle-derived melts incorporated Precambrian crust either in bulk or as partial melts during their ascent, then magmas in the South and Southeast Provinces may have incorporated relatively less crust than did magmas in the Northwest Province (Fig. 5.3). This assumes that in each province the isotopic composition of the crust involved in the process was similar, on average. DllTerent Types of Mantle Contribution The more radiogenic Sr (and Pb; Bouse et al., 1990b) and less radiogenic Nd in rocks in the Northwest Province might reflect contributions from enriched subcontinental lithospheric mantle that formed and attached to the crust in the Precambrian. One model for forming this type of mantle is by volatile fluxing in a subduction zone; because of the P-T dependence of volatile release in the subduction environment it is plausible that enriched mantle forms in belts (sub)parallel to the trend of Precambrian magmatic arcs. Sequential accretion of magmatic arcs (Anderson, 1986) or migration of the volcanic front (Condie, 1982) might cause these linear(?) zones of enriched mantle to coalesce into a broader, regional distribution beneath Arizona. The NW-SE trend of Laramide magmatic centers in this region is virtually orthogonal to the NE-SW trend proposed for Precambrian subduction zones. It is possible, therefore, that the belt of Laramide magmatic centers cuts across a zone of enriched mantle in the northwest. Exposures of basic volcanic rocks that probably formed in an island arc setting are restricted to the Northwest Province, whereas the decided absence of such rocks in the Southeast Province indicates either that island arcs did not form in the southeast or that they are concealed beneath the extensive metasedimentary cover; enriched mantle migh~ also follow this possible distribution of arc terranes. The r-:;;ervations noted above against preservation of enriched mantle in the Laramide subduction environment is an argument against this mechanism. 114 10T------curve \Ie EvolU\IOtl oeple\ed Man 0 "C Z -5 c ~ '00 wCo -10 -15 -20 -25+---~--~--~--~--~--~--~--~--~~~--~ 2.5 2.0 1.5 1.0 0.5 o Age (Ga) Figure 5.3, ENd versus age plot, and mechanisms for generating provincial isotopic differences. The depleted mantle evolution curve of DePaolo (1981a) is shown and various crusts are derived from it. The shaded arrow for 2.15Ga crust could represent either Mohave Province crust formed between 2.0 and 2.3Ga, or a mixture between juvenile Arizona crust formed at 1.75Ga and preexisting ~ 2.5Ga Wyoming Province crust. Each crust evolves with a 147 Sm/44 Nd value of 0.115, with a comparative value of 0.185 also shown for the 1.75Ga Arizona crust. The ranges of ENdr are shown as heavy lines with square and circular terminations for the Northwest and Southeast/South Provinces, respectively. Heavy lines with arrows illustrate mixing between depleted mantle and average Arizona crust. 115 Different Formation Ages of Crustal Provinces The crust in the northwest may have formed earlier than crust in the southeast and therefore evolved to lower eNd and higher 87 Srt6Sr values. Assuming an average 147 Sm/44 Nd ratio in the crust of 0.115 and using the mean eNdy- value of Laramide plutons in each province (Fig. 3.14) implies that the crust is 150 to 200 million years older beneath the Northwest Province. The crystallization and formation ages of Proterozoic rocks in the northwest are slightly older than in the southeast but an age difference of the required magnitude is not supported. Although different crust formation ages do not form a general explanation for the isotopic provinciality, it might explain the low eNd values in the Mineral Park and Diamond Joe systems, both of which lie above crust that contains a 2.0 to 2.3Ga component (Chamberlain and Bowring, 1990; Wooden and Miller, in press). Different Isotopic Ages of Crustal Provinces The crust that contributed to Laramide magmas in the Northwest Province may have been isotopically older than crust involved in southeastern magmatism, even if the two blocks of crust formed at about the same time. The crust in the Northwest Province may represent a mixture (Fig. 5.3) of juvenile crust formed at 1.8Ga with material derived from either the Archean Wyoming Province or the 2.0 to 2.3 Ga crust that may be present in the Mohave Province (Wooden and Miller, in press; Chamberlain and Bowring, 1990; Bennett and DePaolo, 1987). To maintain provincial isotopic distinctions, the Southeast Province had to remain effectively shielded from significant contributions of this older component. An appropriate mixing ratio of crustal components would permit the Laramide magmas to possess similar relative amounts of mantle and crust in either province (Fig. 5.3). An input of Archean or early Proterozoic material into the Northwest Province as it formed at 1.8Ga is consistent with the proposals of Condie (1982), Anderson (1986), and Wooden et aI. (1988), among others. It is also strongly supported by higher 207 Pbf04 Pb ratios, at a given 206 Pbf04 Pb ratio, of Precambrian rocks in the Northwest Province than in the Southeast Province (Wooden et aI., 1988), a trend that is mimicked in Laramide igneous rocks (Lang et aI., 1990; Bouse et aI., 1990b). 116 Geocbemlcally Distinct Provinces If similar processes prevailed during magmagenesis in each province the isotopic provinciality might reflect regional differences in the nature of the crust that was involved, irrespective of whether the crust participated through anatexis or assimilation. One alternative is that the Proterozoic crust in southeastern Arizona evolved to less negative eNd values because it had a higher overall 147 SmJ44Nd ratio than did the crust in the northwest (Fig. 5.3); a slight difference in 147 SmJ44Nd could effect the difference. A higher 147 SmJ44Nd ratio would imply a more basic composition in the southeast. A reasonable explanation might be that the metasedimentary rocks of the Pinal Schist in southeastern Arizona represent a supracrustal succession deposited on a relatively more basic basement, possibly like the Yavapai Series that is exposed in central and northwestern Arizona. Such a relationship has been proposed by Silver and Conway (1989). Models involving the accretion of volcanic arcs or tectonostratigraphic terranes (Condie, 1982; Anderson, 1986; Karlstrom and Bowring, 1988) describe tectonic regimes in which lower crustal compositions in southeastern and northwestern Arizona could easily be different, depending on the compositions of the terranes or the polarity of the arc segments. DllTerent Petrogenetic Processes Petrogenetic processes might have acted upon the magmas in consistently different ways in each province. The variability that may be imparted to magmas through the process of assimilation coupled to fractional crystallization (AFC; DePaolo, 1981b) is one mechanism that could effect isotopic differences in otherwise similar materials; it will receive more attention below. There is at present, however, no compelling reason to call upon a variation in process within this group of magmatic centers that formed parallel to the strike of the descending plate. In a study that documented along-arc geochemical variations in the Andes, Hildreth and Moorbath (1988) proposed that similar petrogenetic processes acted along a great length of the Andean Cordillera and they concluded that the geochemical differences along the arc were best explained by variations in the composition and thickness of the underlying Precambrian crust. The expected constancy in the 117 generative mechanism of arc magmas (Wilson, 1989) further argues in favor of a crustal rather than a process control for the geochemical patterns exhibited by arc magmas in Arizona. In summary, the preceding sections most strongly support the existence of geochemically discrete crustal provinces in which the constituent crust exerted a dominating influence over Laramide magmas that passed through or were generated in it and subsequently emplaced into it. The difference between the provinces most plausibly reflects incorporation of a component of older, preexisting crust into the Northwest Province during its formation as juvenile crust at about 1.8Ga making it isotopically older and probably geochemically The Nd·Sr Isotopic Array Simple bulk mixing is inadequate to explain the data array formed by Nd and Sr isotopes. Mixing models are shown in Figure 5.4; they assume for the mantle a depleted asthenosphere and for the crust a partial melt of an average intermediate orthogneiss generated in the manner described in the caption. No single, two component mixing model is sufficient to account for the full isotopic diversity of the data array. Consistent with the above discussion, mixing curves can be fit somewhat more closely to the data for individual crustal provinces, and even better fits can be made to the data arrays of individual systems by assuming district-specific isotopic heterogeneity. Scatter in the data, however, even at these smaller scales of observation, still argues against simple mixing between relatively homogenous endmembers. Models that use the AFC process can account for the data array without recourse to remarkably different compositions of the crustal assimilant (Fig 5.5) by varying the parameters assumed in the model curves. But there is no compelling reason to expect that parameters in the AFC process would randomly vary when so many othcr geochemical attributes of these magmas, such as their REE behavior, remains so constant and predictable. Certainly, sufficient isotopic heterogeneity exists in the crust (Fig. 5.1) to form much of the data array simply by anatexis of heterogenous Precambrian continental crust. The range shown by Laramide rocks from non-radiogenic to very radiogenic isotopic compositions strongly suggests that heterogenous, Precambrian crust (Fig. 5.1) has been either melted or assimilated during Laramide magmagenesis. The role of Precambrian crust is further 118 Endmembers I A B C 0 Mantle I I S Prov 5 Sro 0.715 0.7150.710 0.704 0.7036 0 ENd ·10 ·15 ·15 ·15 +8 SE Pr~y 6 CNd 25 25 25 25 6 NWtrov I CSr 500 500 500 500 450 0 "C Z c .2 'en 0 Co ·5 W ·10 ·15 0.704 0.706 0.708 0.71 0.712 0.714 Sro Figure 5.4. Binary Nd·Sr isotopic mixing curves between mantle and crustal reservoirs. The mantle endmember is depleted asthenosphere. The crustal endmember is a calculated 50% parlial melt of an average intermediate orthogneiss (Roberts and Ruiz, 1989;, Kempton et aI., 1990), utilizing partition coefficients for basic compositions (Appendix E) and a mineralogy of 40% plagioclase, 30% clinopyroxene, 25% orthopyroxene, 5% magnetite, and 0.5% apatite. The model melt is relatively insensitive to mineralogical changes at F > 0.25, or to F at a fIxed mineralogy. An isotopic composition of probable reservoirs is assumed for the crustal endmember. Percentage of crust is indicated along the curves. 119 , A \1.0 Crust Mantia ABC::> E F : CSr 500 450 0Sr 0.5 1.5 1.5 1.5 1.5 1.5 5 - \ .~ ..... O.S C"Id 25 6 0Nd 1.5 0.01 0.01 1.5 0.01 1.5 : ,'\", ENd ·10 +8 : "'.\ ...... Sto 0.710 0.7038 r 0.1 0.1 0.5 0.5 0.8 0.5 o\s ... ·'" '----___--===:::-:.;:;-=------j \.,.\ 8 o ~--~t_c~~....,~~~------~ u \.~ E ~.~ \~ as" 'C Z· ·5 - CD"',~~ \U " • 05...... --... C ""''-'" ;:l o"io ~~\'...--..... Q .... cP 0 -". 0:::'" a' '/. ":'" =" 0 ~0.5 0.5·,·<1 .... 0.= •••••• 'l. D \o~E '0 - ...... _a. .... :,:~. ..£!. ·10 - o 0 A F 00 o 0 ·15 - I I I I I Crust Mantia A B C ° E F B 500 450 °Sr °Sr 0.5 1.5 1.5 1.5 1.5 1.5 5 °Nd 25 6 0Nd 1.5 0.01 0.01 1.5 0.01 1.5 ENd ·15 +8 r 0.1 Sro 0.718 0.7038 0.1 0.5 0.5 0.8 0.5 8 o ~--~~~------~--~ \0:-5\0 'I • <:~• E ~ ::: \. \. \', :::J 'C . :0" Z· ·5 " ...... \U " "...... :!,pc" .~ "'- = ·10 'n. .. 0.5 ·iF •. c o 0.5 .. ··· o • D .1.'j ·A ...... -.::;::::::.:'''. 0.704 0.706 0.708 0.71 0.712 0.714 0.716 87Sr/86Sr Figure 5.5. AFC models applied to the relationship between ENdT and Sro' A) applies AFe models to a crustal endmember compatible with the South and Southeast Provinces (open squares). B) is applicable to the Northwest Province (filled circles). The parameters for similarly labelled curves are the same in both figures, but the isotopic composition of the crustal endmember differs. The Sr and Nd concentrations in the crustal endmember result from a 25% partial melt of an average intermediate granulite (Kempton et al., 1990; Roberts and Ruiz, 1989). 120 supported by 1450 to 1750 Ma pseudoisochrons defmed by the relationship between 207Pbf04 Pb and 206Pbf04 Pb (Bouse et al., 1990b; Lang et al., 1990). The more limited variation in isotopic composition shown by individual magmatic centers relative to Laramide magmas as a whole or by crustal province is compatible with scenarios in which mantle melts assimilate, or in which anatexis affects, crustal materials that have less variation in isotopic composition on the local scale than on the regional scale. The isotopic composition of the early volcanic rocks suggests that they might retain a substantial mantle component. Decoupling of Sr and Eu Behavior Many of the Laramide melts have Car that is higher than that expected for mantle melts. Simple mixing between mantle melts and typical crustal rocks cannot account for the wide range of Car in the magmas unless the assimilants had a very large range in composition which is further complicated by the need, in some cases, to call upon assimilants that coupled high 67 Sr f6 Sr to very high Car' Modeling of fusion in the relatively Sr-rich lower crust shows that high Car magmas can be readily generated. To illustrate this, rocks with typical lower crustal mineralogy of 25 - 50% plagioclase, 25 - 40% clinopyroxene, 0 - 25% orthopyroxene, 0 - 15% hornblende, 0 - 5% magnetite and 0 - 5% garnet were subjected to 10 - 50% modal batch melting to yield both acid and intermediatejbasic magmas. (The necessary equations and mineral-melt partition coefficients may be found in Appendix E). Values of Dsr range from 0.55 to 0.95 for basic compositions and 1.0 to 2.0 for acid compositions. These DSr values give a range in the ratio of the concentration in the model melt to the concentration in the parent, Ca/q lCaro, of 0.5 to 0.95 and 1.0 to 1.7 for basic and acidic compositions, respectively. Because Car in lower crustal xenoliths often exceeds 500ppm even the highest Car values observed in Laramide igneous rocks can be produced, either through crustal anatexis or through high percentage assimilation of these partial melts into mantle-derived magmas. There is a correlation between Car and Sro (Fig. 5.6A). The correlation is broad and rather weak for the data overall but individual districts behave more regularly. The magmas in a system evolve toward much lower Car and somewhat higher Sro with time. The simplest explanation is that Dsr increases generally, although with some reversals, as magmatism in the systems progressed. 121 Figure 5.6B illustrates this relationship assuming an AFe process, and shows further that significantly different amounts of crust need not be assimilated to account for the relationship. Steadily higher values for Dsr should not be surprising in these melts, because substantial fractionation of plagioclase, the only abundant mineral phase with Kd Sr greater than one, is expected and because later magmas are more acidic and crystallized at lower temperatures than did earlier melts, further promoting larger Dsr values. The inconsistency that arises in this simple scenario is that the REE profIles do not acquire, with the exception of a few highly differentiated rocks such as the Red Boy and Tombstone Rhyolites, the increasingly negative Eu anomaly that characterizes plagioclase fractionation; indeed, the opposite trend is the actual case. Several factors might contribute to the decoupling of Sr and Eu behavior. Although Drake and Weill (1975) showed that G:u and Dsr are different functions of temperature, and probably also of composition, neither is likely to effect retention of Eu in preference to adjacent REE. Oxidation state in the magmas may, however, contribute to decoupling. The higher oxidation state of the late stage, productive melts (Hess, 1986; Mason, 1978, Mason and MacDonald, 1978) relative to earlier, barren magmas would lessen the Eu anomaly imparted to these magmas for a given degree of plagioclase removal. However, even in the very oxidizing plutons at Sierrita (Hess, 1986) plagioclase has large positive Eu anomalies (Anthony and Titley, 1988), and the few log units variation in f~ that might be expected among these stocks appears insufficient to account fully for the decoupling of Sr and Ell, although it could certainly contribute to it. A more satisfactory explanation is that the anticipated decrease in Eu/Eu·, or at least a part of it, was offset by the removal of other mineral phases with negative Eu anomalies, such as monazite or hornblende, or reflects different conditions or assemblages being melted in the crust. These possibilities are discussed further below. Rare Earth Element Behavior The most convincing evidence for constraining the evolution of Laramide magmas comes from their consistent patterns of REE behavior. The REE trends demonstrate that a systematic process has affected each Laramide magmatic center in a similar fashion, against the background of their predominant source in heterogenous Precambrian crust that was demonstrated by isotopes. 122 0.716 -,------~ Tombl1OnD : 0.714 SIent1a Ray/Xmaa 0.712 ... CopperCr en Saffold ~ 0.71 • • CopperBs en1::- .. I' Bagdad CO 0.70B • OIa.Jou 0.706 0.704 0.716 ..,..-;;:;-----;~------~ r=Q.2. 0.714 .... ~.\1 ...... 0.95 .. 0.85 0.712 en... . \ . ~ 0.71 \'~~ \.. 1::- • ~ CO 0.70B · \ ';k· 0.4 \ .~.""- 0.706 o~~-~ • largerr '-, - .. 0.10 0.704 o 200 400 600 800 1000 1200 Sr (ppm) Figure 5.6. Relationship between Sr and CSr' A) Arrows delineate general temporal trends in composition for each district. B) Aif APe parameters except DSr are held fixed. The endmembers are the same as those in Figure 5.5B. The arrows indicate that the curves approach the D r = 1 line as the value of r is increased. The numbered tick marks on the curves indicate F, the wei~t fraction of the original magma remaining. The plot is contoured for the ratio of the mass of assimilated material to the mass of original magma, ~/~ 0 = (r/(r-l»(F-l) (see Appendix E for definition of terms). 123 The most plausible mechanisms by which this might be accomplished are fractional crystallization in comagmatic igneous systems, melting processes that systematically affected the composition in the source region of the melts, or hydrothermal fluid loss. TIle Effects of Fluid Loss. One property common among productive plutons is the release of hydrothermal fluids. The amount of fluid lost from a magma might logically be expected to increase from barren to subproductive to productive stocks, paralleling the smooth evolution in REE behavior. Although the effect of fluid removal on the REE profUe of a magma is difficult to assess because few high temperature, experimental studies of the process have been undertaken, it is clear that some modification of magmatic REE profUes is possible. Fluids rich in F are capable of significant mobilization of the REE (Humphris, 1984; Barovicll, 1991) and Cl-and C~-rich fluids may also be effective mobilizing agents under some conditions (Humphris, 1984). London et al. (1987) reported that F-rich fluids in siliceous magmas preferentially incorporate the HREE over the LREE. Fluids associated with porphyry copper deposits are, however, poor in F and high in Cl (Beane and Titley, 1981) and are probably not effective agents for preferentially depleting productive stocks of HREE. Flynn and Burnham (1978) reported a preference of Cl-rich fluids for the MREE; Candela (1990) expanded on this by showing that under conditions of T, f~, ~ 0, and Incl appropriate for magmas associated with porphyry copper deposits as much as one-half of the Eu originally in a melt might be removed by an exsolved aqueous vapor phase. The ability of Cl-rich fluids to effect a decrease in Eu/Eu· suggests that the increasingly higher Eu/Eu· values observed over time may actually represent a minimum change. Fractional Crystallization Effects Fractional crystallization processes have probably modified the geochemistry of many of the magmas. In these systems, the fractional crystallization process might be operating directly on a comagmatic suite or, as an alternative, on a suite of rocks that underwent similar generative processes, but that subsequently carried fractionation to different endpoints. Figure 5.7 shows that 124 fractional crystallization can be made to describe the REE evolution of the Ray/Christmas system as a comagmatic suite. The Tortilla Quartz Diorite is easily generated by partial melting (15 to 40%) of an average, lower crustal, intermediate granulite (Roberts and Ruiz, 1989; Kempton et al., 1990), followed by fractionation of plagioclase and clinopyroxene. The later magmas can be obtained by fractional crystallization of an assemblage of plagioclase and hornblende, accompanied by small amounts of allanite, monazite, and titanite to account for the increasing compatibility of the LREE with time (Miller and MiddiefeIdt, 1982). The fit of the model to observation is intriguingly close, but upon greater consideration the relationship cannot be so simple. The major minerals in the fractionating assemblage, hornblende and plagioclase, are typical of the phenocryst assemblage in most of these rocks, and of cognate inclusions that occur in some stocks. Fractionation of hornblende can account for the trend toward more peraluminous compositions (Fig. 3.2; Cawthorn and Brown, 1976), and might also account for the decreasing K/Rb values discussed below. But precise reproduction of the REE patterns requires the removal of phases relatively uncommon in the fractionating assemblage typical of calc-alkaline systems, such as allanite and monazite, and some aspects of the patterns, such as the low abundance and concavity of the HREE, are difficult to reproduce at all without fractionating garnet. Each of these accessory minerals occurs in Laramide plutons but their small size inhibits physical settling from the melt as individual grains (although they could be removed as inclusions in phenocryst phases). Furthermore, garnet is only known from one stock, allanite typically occurs only in late stage plutons, and monazite is uncommon although it is reported (Cornwall, 1982). These phases ne unlikely to effect the broader REE evolution of each igneous system. Moreover, the major and trace element behavior in most systems precludes their full complement of igneous rocks being a comagmatic suite, e.g., Ray and the Santa Rita Mountain suite, but they nonetheless display the same overall REE evolution as systems that appear more amenable to treatment as comagmatic suites, such as the Bagdad district. Isotopic results show most clearly that these systems cannot be treated, in whole, as comagmatic suites. Finally, many systems experienced magmatism over such extended periods, up to 20 million years, that comagmatic relationships are unlikely. Neither is the 125 01_ compOSJuon J!~ AI.t<;w!eOIe Rocks In tho Ray/Christmas District f5~ OtII1oQyro>cene 15~ C/inoayroxene 65% "'aqlocillSe 2~ Aoable aD 20% Partfal MaH 01 Inllrm OranUllte lallowed 60 bV 411% Frlet. CryaL DI 90plaglOCpx ,/' 40 ~ a: Ten/lla Quanz Dlante ~ 20 o BasJcl'tlase :z: .... ~ ..... u 10 ..... - Ac';d""ase o a: Teacup Grlll1D01Dll18 ~~ernbiage 2 27.8% Q/aqlacWe 0.5% zirccn 1.5% ut&lllle 0.2% 51_ La Co Nd Sm Eu Gd Tb Ho Er Tm Vb Lu La Co Nd Sm Eu Gd Tb Ho Er Tm Vb Lu RARE EARTH ELEMENTS Figure 5.7. Fractional crystallization models applied to REE behavior in the Ray and Christmas districts. A) shows the results of model REE curves. The dashed curve is an average intermediate granulite xenolith (Kempton et al., 1990; Roberts and Ruiz, 1989) whose mineralogy is indicated on the figure. The heavy solid profile is derived from the granulite as indicated. Light solid curves are derived from the model melt (heavy line) by varying F and fractionating the assemblage indicated on the figure. B) Average REE profiles of intrusions from the Ray and Christmas districts, and the productive porphyry from Dos Pobres. 126 evolution likely to result from differences in an AFe process. The profiles of the REE are relatively insensitive to changes in the parameters of this process and are therefore unlikely to be more greatly modified by it than by simple fractional crystallization, although total REE abundance might be affected considerably. A positive result of this modeling exercise, however, is that fractional crystallization could readily generate the REE signature, or a part of it, of some of the igneous rocks through hornblende and plagioclase fractionation; the productive porphyry at the Dos Pobres deposit may be an example of this. The patterns of REE evolution might result from the influence of a consistent style of fractional crystallization that progressed to different endpoints but that otherwise acted upon magmas that were generated in a similar fashion and with similar initial geochemistry. To explain the temporal trends, however, the underlying cause of the process would have to be systematic; otherwise the fractionation process would need to fortuitously progress to a similar endpoint for each magma occupying a given stage in the sequence of each igneous system. One process that might be sufficiently systematic is progressively greater assimilation of a hydrous crustal rock type such as amphibolite; this process is further discussed below. Burnham (1981) pointed out that earlier water saturation in a magma promotes earlier stabilization and more abundant formation (and removal) of amphibole. Therefore, the greater role for hornblende suggested by REE patterns could be accounted for. Increasing assimilation of amphibolite is also consistent with the model proposed by Anthony (1986) for the geochemical evolution of igneous rocks in the Sierrita system. Fractional crystallization processes, although they may not be the predominant cause for the full spectrum of trends displayed in these systems, probably do account for the relationships among some portions of the igneous lineage in each magmatic center. In a few cases this can be demonstrated. The Diamond Joe stock has REE behavior that differs from that observed in other systems (Fig. 3.8B) and probably reflects (nearly) closed system fractionation in a single pulse of magma. The concentration of the HREE remains relatively constant but the LREE are progressively depleted in the patterns of later magmas. The Eu/Eu'" values decrease regularly and the profiles become preferentially depressed in the MREE. The late-stage differentiates have REE 127 proflles not dissimilar to the highly differentiated rhyolites in other systems. In this stock the REE budget was probably initially controlled by hornblende and titanite in the marginal granodiorite phase, then later by plagioclase. This style of evolution may also be reflected in the progression from main phase granodiorite, to older quartz latite porphyry, to younger quartz latite porphyry at Copper Basin, but it is not evident in any other Laramide system examined in this study. The igneous systems in the South Province underwent a REB evolution slightly different from systems in the Northwest and Southeast Provinces. In the South Province, both the HREE and LREE are progressively depleted, as they are elsewhere, but the magnitude of the reductions is less. In addition, the Eu/Eu· values do not vary as much as in other systems. In contrast to systems in other provinces, the REE proflles of the later intrusions in systems in the South Province are more easily derived from the earlier igneous rock types by simple removal of plagioclase and hornblende, without recourse to unusual mineral assemblages. The Red Boy Rhyolite and the Tombstone Rhyolite are probably the product of similar fractionation processes in a more voluminous magma, by analogy with late differentiates of the Diamond Joe stock. The K/Rb ratio is potentially useful as an indicator of interaction between magmas and crust, and of the processes that act upon the magmas. This ratio is difficult to modify by fractional crystallization processes because most potential fractionating phases, such as clinopyroxene, plagioclase, Fe-Ti oxides, titanite, and zircon, have very low and similar Kd values for both K and Rb, but biotite, potassium feldspar, and possibly hornblende may be exceptions to this. Figure 5.8 illustrates the relationship between K/Rb and Rb. A substantial decrease in the K/Rb ratio is evident with increasing ~b' The greatest variation in K/Rb is among rocks with basic compositions with little corresponding variation in ~bi in these rocks, phases with very low affinity for K and Rb would be expected to dominate the fractionating assemblage, e.g., pyroxene, olivine, and Fe-Ti oxides. The later, more differentiated stocks have a smaller range in K/Rb values but greater variation in ~b j these rocks are more likely to be affected by phases with a stronger afrmity for K and Rb, e.g., plagioclase, hornblende, biotite, and potassium feldspar, and fractional crystallization is 128 700 I K Rb OK ORb I 1 0 I BC (Bulk Crust) 9100 32 --20op20cp6001 0.11 0.05 ~ • • UC (Upper Crust) 28200 112 ...... 15cp30hb5501 0.39 0.13 600 'K, ' 500 '; . '---.. :\ ~ ••• 0.6 ---_____~F ~.~0.1~ ___~S~c .. ~'~-~a~.2 .c .\.~~ c: 400 .. 52. .'\~ .- 0.1I·l. .~ 0.2 SC;,ao.6 • .....:.~. 0 0.6 ----"------.-::..:..:.:: ";fi7 __ --:-____.::0.;:.4 ___~/JC;~. ,:..:.::o.~6 300 ...... ff'...... • • I ". .. .•.. , . • ; ...... ;.,... 0.4 •• • .."I' ... :,~_...... 1'...... UC.. ,-o.6 200 • • • .iI' •• ~...... _ • •••. .0.2 ...... ,• SC;,aO.6 100 • 700 ! 3p11@930to1120 , 1.0 0.7 04 • ••~~.3~~0:.2~~0.~15~ ":'/" __~0.1 ______~~~~~~~ F . 600 O.B, .••• :' •••••• /-.. - 0.05 0\6' ...... • ... / ...... 1'...... 5mt16oI350p16cp30pl .•. -...... -.... ---.... -.. -...... ~ ...... -... -.. •• _- 200p20cp80p1 500 , 0.4'· • . ... 0.3 ". acid §IJ\\.. ". ••- .c M'''''''~ \. 0.2-. ! c: 400 . '\ , I 52 .. '- • 0.15·.... 15cp3O/1bMpI .",,~ . 0.1 .-- I --.~ . , 300 .. , . basic • ...... I. • I. I. 0:05------~ .. ,'. :. • •• -ttl :: ...... 200 .. .. • 100 o 50 100 150 200 250 Rb (ppm) Figure S.S. Fractional crystallization and AFC models for the relationship between K/Rb and Rb. A) AFC models. The mineralogy of the fractionating assemblage, r values, and bulk partition coefficients, D, are indicated for each curve. D values were calculated from the partition coefficients tabulated in Appendix E. UC indicates that an average upper crustal assimilant was used and BC indicates an average bulk crust assimilant (Taylor and McClennan, 1985) .• Tick marks indicate F, the fraction of the original magma remaining. 8) Fractional crystallization models applied to the same data as A). Tick marks indicate the fraction of melt remaining. The mineralogy of the fractionating assemblages are indicated on the curves. The lower two curves show the difference that results when acid and basic partition coefficients are used for hornblende bearing assemblages. 129 therefore more likely to affect CRb' However, the increase in CRb requires the responsible phase to have Kd Models illustrating the effects of crystal fractionation, AFC processes, and bulk mixing are shown in Figure 5.8. In the calculations the basalt phase of the Williamson Canyon Volcanics is used as the basic endmember. This magma is the least evolved Laramide igneous rock examined in this study and its ENdr value near 0 establishes it as among the more 'priuitive' rock types. Three samples, CB41, SF33, and D22, have very low CRb and K/Rb ratios higher than the Williamson Canyon basalt, but none of them are adequate for the basic endmember; CB41 and SF33 have experienced some hydrothermal alteration that makes their CRb suspect, and D22 is a dacite dike from the Diamond Joe system. Fractional crysta11ization alone does not appreciably modify the K/Rb ratio. The highest CRb values require over 90 percent crysta11ization, irrespective of whether Kd values appropriate for acid or basic compositions (Appendix E) are used. Major element data do not support this degree of fractionation. The only curves that approach the pattern of the data involve large amounts of hornblende. AFC models more adequately describe the data. The basic endmember is the same as above and both bulk and upper crust (Taylor and McClennan, 1985) are used as assimilants. The bulk partition coefficients for Rb and K were calculated from the mineral assemblages used for fractional crysta11ization in Figure 5.8A (Appendix E). Values of 0.2 and 0.5 are assigned to r. There is little difference between the shapes of the curves for upper versus bulk crust, at fIxed r; assimilation of nearly twice as much bulk crust as upper crust is required, however, to reach a given CRb' Models that fractionate predominantly plagioclase and hornblende are most effective at modeling the data and can do so with more reasonable degrees of fractionation. Bulk mixing bctween the basic magmas and upper crust describes a broadly appropriate curve; the CRb values above 110 ppm would require enhancement by advanced, late stage fractionation processes. The models suggest that much participation of crust, with or without accompanying fractional crysta11ization, may be necessary to effect the behavior of K/Rb ratios in these magmas. Regardless 130 of whether fractional crystallization or AFC processes are involved, only the models that involve large amounts of hornblende are likely to account for the variation in K/Rb ratios in the early rocks. Partial Melting ElTects Differences in the conditions of melting in the source region can also account for the REE behavior in these systems. More specifically, these include melting distinct source rocks, variable degrees of partial melting of similar sources, or modification of source regions with time. Although melting of petrologically unique source regions is not supported by the isotopic data, the systematic REE behavior might still be accounted for by vertical migration of melting isotherms through a compositionally layered crust. Broadly different types of crust, such as pyroxenite versus amphibolite, probably have sufficiently heterogenous isotopic compositions to account for the isotopic signatures of Laramide stocks. Although unable to account for the general geochemical evolution, unique source regions are implied for a few igneous rocks. One example is the basalt in the Williamson Canyon Volcanics. Its flat REE profUe and positive Eu anomaly may result from mixing between mantle-derived basalt and volumetrically minor crustal materials, which is consistent with its relatively primitive isotopic signature. As an alternative, it might have formed by high degrees of melting of a crustal rock, possibly similar to the pyroxene metacumulate granulite xenoliths described by Kempton et al. (1990) or similar xenoliths discussed in Roberts and Ruiz (1989). Its Src value of 0.7015 is similar to values measured on some exposed Precambrian volcanic rocks of basic composition; even if this low Sra value is the result of post-emplacement alteration, the measured 87SrjlSSr value of 0.7043 remains consistent with derivation from a basic crustal rock that maintained a very low time-integrated Rb/Sr value. A second example is the Elephant Head stock in the Santa Rita Mountain suite. It was probably derived from a crustal source with a metasedimentary progenitor; if so, this is the only example of such parentage recognized in this study. Such a source is indicated by its elevated REE abundance, the shape of its REE pronIes, its elevated Th, U, and I<20 concentration, and its low NazO, Sc, Co, and Ni content. It is also possible that a magma similar to those which produced the 131 bulk of the main stage plutons in these systems assimilated a very large proportion of metasedimentary material and then underwent large degrees of crystal fractionation. Systematic REE behavior can also be caused by subjecting a given source region to a sequence of partial melting effects but this is unlikely. The progression of REE profIles can be forced upon a typical crustal source by sequentially melting it and then its restite, thereby depleting the residuum in REEj but this is &Jl unlikely mechanism because it is opposite the expected course that melting should take. The fertility of a given source region will decrease as melts are withdrawn from it, causing it to become increasingly dehydrated and devolatilized. The ability to continue melting diminishes with time unless rehydration of the source region takes place (Black and McCulloch, 1990j Vielzeuf et al., 1990). Furthermore, the presence of porphyry mineralization associated with the late stage, productive magmas implies that they were rich in volatiles, but remelting a given source region would lead to the opposite. But in this case also, upward migration of isotherms as the crust became heated, or as crustal rocks were pushed deeper under the compressive tectonic regime of the Laramide, could maintain a flow of fertile material to the zone of melting in the crust. Synthesis Introduction The following features of Laramide magmatic systems and their associated mineralization must be accomodated by any effort to model their petrogenetic evolution: 1) each magmatic center evolved along a generally similar pathj 2) the major and trace element data imply that the generative mechanism of the Laramide melts was probably similar through time, and reflects their degree of differentiation rather than their temporal position in the local magmatic sequence; 3) the REE data demonstrate that a systematic process was affecting the magmas according to their timing in the magmatic sequence, irrespective of their major element composition; 132 4) trace element and REE data imply that hornblende became increasingly involved as each magmatic system progressed; 5) the isotopic data support the retention of a mantle component in the early volcanic rocks, but suggest that subsequent intrusions were derived predominantly from the crust; 6) the population of intrusions in most districts does not follow any consistent temporal trend in isotopic composition; 7) the porphyry copper deposits always form late in the magmatic sequence of a district, but not necessarily in association with the most differentiated intrusions; 8) there is very little difference, overall, between productive and barren intrusions; productive stocks represent a natural step in the evolution of these magmatic systems. In the following sections, the various mechanisms that might cause the observed, consistent geochemical trends and the evolution toward porphyry copper mineralization in Laramide magmatic centers are considered in the broader context of magma production at the Laramide convergent margin. Processes Affecting Laramide Magmagenesis Cause of Melting. Because Precambrian continental crust is the dominant component in Laramide magmas the mechanisms that cause it to melt are important to a general understanding of magmatic and metallogenic processes. In southern Arizona, Haxel et aI. (1984) proposed that crustal loading and thickening by thrust sheets drove crustal anatexis. Barton (1990), however, noted that the thrusting discussed by Haxel et al. (1984) was contemporaneous with magmatism and did not allow sufficient time for the lower crust to reach anatectic temperatures. A second mechanism, decompression melting caused by rapid uplift, is not supported as a general mechanism. Barton (1990) attributed magmatism in the eastern Great Basin to an increased mantle heat flux that gradually warmed the crust, leading to progressively larger crustal contributions to mantle-derived 133 magmas over time, and eventually leading to dominantly crustal melts represented by younger, strongly peraluminous plutons that typically culminate late Mesozoic-early Tertiary magmatism in both the Great Basin and in Arizona. A similar igneous progression is observed in Colorado (Stein ond Crock, 1990). A broad heating of the crust might plausibly be accomplished by injection of basic, mantle-derived magmas; such basalt injections could also lead to local heating phenomena, if the centers of injection were sufficiently well separated. These intraplating or underplating mantle melts probably Cormed, as proposed by many workers (see review in Wilson, 1989), as a consequence of volatile release, either as Cree fluids or as volatile-charged, siliceous melts, Crom the dehydrating, descending slab, and any sediment cover that accompanied it or was entrained within it. Hydration lowered the peridotite solidus in the overlying mantle wedge and triggered melting (Wyllie, 1981). The wedge-derived magmas then rose into the base of the overlying continental crust, at which point some of them might have followed the unlikely course of ascent as relatively uncontaminated melts, or the more likely cases in which they mixed with or assimilated continental crust, or induced crustal anatexis. The Crustal Environment and the Ascent of Magmas. Early in Laramide time the crust was probably cooler than at later stages. A smaller density contrast between hot, basic magmas and the cooler, less basic crust would prevail initially and the crust would also have a more brittle nature. Some basic magmas would be able to rise to high crustal levels and might even erupt at this stage, even if the bulk of them remained in the deeper crust (Fig. 5.9). Over time, the heat flux from intraplating magmas warmed the crust (perhaps only locally), the density contrast diminished, ductile behavior supplanted brittle, and the ascent of basic magmas was arrested in the lower crust. At this point further ascent required fractionation of primary magmas to more bouyant compositions or generation of bouyant secondary melts by crustal fusion. As basalts pooled in the lower crust their latent heat of crystallization was sufficient to melt substantial volumes of crust (Huppert and Sparks, 1988; Hon and Weill, 1990; Patchett, 1980) and partial melts of up to 50 percent could have formed, even in the absence of fluids, at temperatures between 800 and 95[f C (Veilzuf et aI., 1990). Increasingly favorable thermal conditions would permit increased bulk assimilation of crustal 134 Early laramide; Cool, brittle crust --;:.. Early volcanic rocks retain a mantle component ...." ...;.....;.-'-~::;.....:""-:--'-~l-..'--__ Continental assimilation Crust of crust probable anatexis? , - '\ Intraplatlng basalts Mantle Wedge Slab Figure 5.9. Generation of early volcanic melts In the Laramide magmatic arc. 135 material, greater degrees of crustal anatexis, and/or migration of the melting front to progressively higher levels in the crust. Crustal anatexis processes may be preferred over assimilation processes from thermal and density arguments (Hubbert and Sparks, 1988) that do not favor mixing between the mantle basalts and their anatectic products, and the fact that crystallizing magmas may form a cooling rind that inhibits mixing (Takahashi, 1986). Anthony (1986), however, effectively modeled the Sierrita magmatic system as one in which mantle-d\lrived magmas progressively assimilated mafic crustal rocks. Although crustal anatexis is more compatible with the isotopic composition of the later Laramide magmas, the presence of a (small) mantle component in them cannot be dismissed. The structural environment had a significant effect on the emplacement of Laramide magmas. Magmatism was concentrated at major structural intersections (Titley, 1981) where local extension may have occurred even within the environment of overall compression that characterized the Laramide (Rehrig and Heidrick, 1976). The basic to intermediate volcanic rocks reached the surface early (the Baboon Metavolcanics may be an exception) when the cooler, more brittle crust combined with an extensional environment to facilitate their access to the surface. Their major element (Miller and Barton, 1990; Cameron et al., 1989) and isotopic signatures indicate retention of a mantle component (Fig. 5.9). Continued activity along localizing, extensional structures maintained conduits of access to the upper crust for the later magmas, but higher temperatures and greater interaction with the crust made retention of a prominent, identifiable mantle component difficult; this is reflected in the more negative eNd and higher Sro values of most of the later, more acidic granitoids. The Level of Crust Involved. The lower crust constitutes the major portion of the crustal component of the main stage granitoids. Ponding of basalts in the lower crust and the generation of a thermal environment conducive to anatexis strongly supports this assertion. A lower crustal source is further implicated by: 1) oxygen isotope data from Laramide magmas elsewhere in the North American Cordillera (Miller and Barton, 1990); 2) the presence in deeply eroded plutons in the Mohave Province of an inherited component in magmatic zircons that is older than the age of the local upper crust (Miller et al., 1990; Chamberlain and Bowring, 1990); 3) U-Pb isotope data that 136 require interaction of Laramide magmas with a U-depleted Proterozoic crust (Wooden et al., 1988; Miller et al., 1990); 4) high Sr concentrations that are more compatible with derivation from Sr-rich lower crustal rocks than from Sr-poor upper crustal rocks; 5) the difficulty of intermediate to acidic magmas near their solidus to evolve sufficient heat to effect significant melting of upper crustal wallrocks; 6) the range in geochemical characteristics of the Laramide magmas is more similar to the range found in lower crustal xenoliths than to the range found in upper crustal rocks. Limited exchange of the more mobile components at higher crustal levels cannot be completely ignored, and might have influenced some features of Laramide magmas. The elevated Sro values of the Bagdad system relative to other magmatic centers in the Northwest Province may be, in part, a result of this. The magmas at Bagdad passed through the thick sequence of Precambrian intrusions in the Bagdad Reflection Sequence (Clayton, 1991) and had ample opportunity to interact with them; indeed, the Blue Mountain Stock contains many xenoliths of Proterozoic intrusions, although contacts between the Laramide intrusion and its xenoliths are usually sharp and do not imply bulk assimilation. Farmer and DePaolo (1987) demonstrated a transfer, via hydrothermal fluids, of very radiogenic Sr from the 1400Ma Oracle Granite into the 70Ma San Manuel stock, and similar processes could have affected the Bagdad system considering the proximity of altered rocks to Proterozoic wall rocks, and the presence of hydrothermal alteration in some samples (Table 3.1). Mechanisms For Producing the Observed Geochemical Behavior Three separate, but in large part related, mechanisms might plausibly account for the predominance of the crustal component in Laramide intrusions, and for the increasing participation of hornblende over time in each system. The models are summarized schematically in Figure 5.10, and include: 1) melting lower crustal rocks that were undergoing gradual hybridization (metasomatism) by fluids; 2) increasing assimilation of hydrous crust into mantle-derived melts as the crust warmed; and 3) migration of the anatectic front from deep, anhydrous source rocks for early melts to progressively shallower, more hydrous source rocks for the later magmas. Metasomatism and upward migration of the melting front cause progressively greater hornblende to Later laramide; Warmer crust Shift to anatexis of Increasing assimilation of Upward migration of melting hybridized lower crust crust by mantle melts front through the crust /'it -:-.- ~ ~~ --// )~::. :=:=:- ~~~---=-=- 0~ - later. high level stocks iiie_ "'''' hydrous ~~a crust o ~2 3 - - 3 asslmllallon progressive '--, hybrldlzallon / / anatexis \ Intraplallng ---- 1 melUng -~ Jess hydrous front ~ crust ~~+.... ~ \ .... basalts / / Il>Il> ., Cl / /voialiles. ;V./ c-o / "'CD fluids, :i:~ siliceous /1.../ /' melts .0 Figure S.W. Models describing the generation of intrusive rocks In the Laramide magmatic arc. Each model is described in detail in the text. A) describes metasomatism of the lower crust by mantlc- derived fluids. B) is a model of progressively greater assimilation of hydrous continental crust in response to a progressively heating crust. Larger arrows correspond to .... greater assimilation. C) is a model in which the anatectic front moves to progressively higher, more hydrous crust as the crust W is continually heated by intraplating basalts. -...J 138 be present in the residuum of crustal anatexis, whereas assimilation of hydrous crust influences the water content of the magmas such that greater hornblende removal occurs as a magmatic system evolves. HybricUzation (Metasomatism) of the Lower Crust. The critical feature of this model is that fluids and volatiles derived from the slab or mantle wedge progressively altered the lower crust to a more hydrous, perhaps amphibolitic, comr;osition (Fig. 5.10A), thereby providing the hornblende necessary to form the systematic REE patterns. Figure 5.11 shows that the trends in REE behavior can be largely duplicated by increasing the participation of hornblende in the source region through hybridization. The fluids and volatiles maintained or episodically regenerated the fertility of the crustal source of the Laramide melts, allowed melting to persist in narrow columns of continental crust for extended periods, and also provided volatiles necessary for the formation of porphyry copper deposits in the upper crust. The limitation to this method might be whether or not adequate means for transporting the metasomatizing agents into the lower crust exist. Movement of free fluids from the downgoing slab across the mantle wedge was probably precluded by the formation of partial melts of peridotite (Wyllie, 1981). The intraplating basalts themselves would have been water-undersaturated (Wyllie, 1981; Vielzeuf et al., 1990) and therefore could not have released volatiles into the crust as they cooled. The most promising transport medium was volatile-charged, siliceous melts that formed in the downgoing slab (Wyllie, 1981; Wilson, 1989), some of which might have passed through the mantle wedge and released their volatiles into the lower crust as they crystallized. The most concrete support for crustal metasomatism is the many examples of hydration events that are preserved in lower crustal and upper mantle xenoliths that attest to the presence and movement of fluids at these levels; they usually manifest veins and replacements of anhydrous mafic minerals by hornblende and phlogopite. The metasomatic process should operate independently of the composition of the crust above the subducting slab, and therefore does not require specific compositions or layering of preexisting rock types, as in the other two models; it is a process that could cause porphyry style mineralization in any type of crust above a subduction zone. Depletions of base metals and HFSE, particularly in the late stage productive stocks, can be explained either by 139 Source Hybridization by Fluids 200 Rocke In tho Ray/Chrlstmaa District 60 40 W Increasing amphibole, f- decreasing pyroxene a: TOIIIlla Oullltr Dlonte Q 20 in source Z 0 84S1oPhlslt :c ... ~ (J i2 (J 10 A 0 a: B C 5 opx/cpx/hbl/plag D A 25/25/0/50 E B 20/20/10/50 C 20/5/25/50 2 D 10/5/35/50 E 0/0/50/50 25% Melt in source La Co Nd Sm Eu Gd Tb Ho Er Tm Vb Lu La Co Nd Sm Eu Gd Tb Ho Et Tm Vb Lu RARE EARTH ELEMENTS Figure S.11. ElTects on REE behavior of source hybridization by fluids. A) The REE proflIes were produced by 25% partial melt of a source with the mineralogy indicated in the lower left. B) Average REE proflIes of intrusions from the Ray and Christmas districts, and the productive porphyry from Dos Pobres. 140 their retention in a hybridized restite, or by a source depletion through early removal into HFSE-rich magmas (e.g., the Tortilla QUartz Diorite and Schieffelin Granodiorite), and need not be ascribed to removal by hydrothermal fluids, as Baldwin and Pearce (1982) proposed for Mn depletions in productive Chilean stocks. The role of fluid removal in these systems is certainly complex, however, considering the base metal haloes that commonly occur on the periphery of porphyry copper deposits (Lang and Eastoe, 1989; Jones and Leveille, 1989). Finally, the presence of the hybridizing fluids might not be easily recognized. The isotopic signature of the hybridizing fluids, even if it was originally much different than that of the mantle or lower crust would, because it probably had low REE concentrations, have been effectively masked by the volume of basic magma produced in the mantle wedge, and by the overwhelming role played by isotopically heterogenous, Precambrian continental crust. The model of hybridization of the crust by fluids is complementary to the style of crustal hybridization envisioned by Asmerom et al. (1991). They proposed that during Jurassic arc magmatism in southern Arizona injections of basic, mantle-derived magmas hybridized the lower crust and these magmas themselves became an increasingly important contributor to subsequent melts. This mechanism accounted for their observation of a greater mantle signature in younger Jurassic magmas. They did not discuss the role of fluids or metasomatism. In contrast, the isotopic data for Laramide magmas favor a greater mantle signature in the early melts; therefore the melting conditions in the Jurassic arc may have differed from those in the Laramide arc. More specifically, fluid hybridization would promote greater crustal anatexis in the Laramide case, whereas its absence might lead instead to an increasing input from relatively fertile, intraplated basalts in the Jurassic case. Increasing Assimilation of Hydrous Continental Crust. This model has been touched upon above and is summarized in Figure S.lOB. As intra plating basalts continued to warm the crust, the thermal barriers to assimilation lessened. Mantle-derived, basic magmas could then have incorporated progressively greater amounts of crust as magmatism continued in a given column of 141 crust. The crustal assimilant might plausibly have been hydrous amphibolite whose incorporation would have increased the water content of the magmas and driven the melts to greater production and removal of hornblende over time. This model was proposed by Anthony (1986) to explain isotopic trends in the Sierrita system and is certainly a plausible explanation for the isotopic difference between early volcanic rocks and later plutonic rocks, and could also account for progressively greater volatile contents in the melts. The isotopic data for most districts, however, do not show the clear temporal trends that were evident at Sierrita, and therefore do not fit the model as well. Isotopic heterogeneity in the crustal assimilant might make monotonic temporal trends in isotopic composition an unnecessary requirement. Upward Movement of the Anatectic Front. This model (Fig. 5.10C) envisions that over time the crust became progressively heated and the melting front moved upward from anhydrous lower crust to progressively more hydrous rocks higher in the crust. It is similar in its implications to the model of metasomatism in that hornblende is increasingly important in the restite, but has the advantage that it is much simpler and does not require the input of exogenous fluids. A disadvantage is that it implies that continental crust at convergent margins is similarly layered, from deeper, dry crust to less deep, wetter crust. Even at the scale of Arizona, it is unknown whether this type of layering occurs. Implication of the Models for Metallogenesis Water and Volatiles. Each model in Figure 5.10 has practical implications for metallogenesis. The most important effect may be that they can provide volatiles necessary for the formation of porphyry copper deposits and they provide the systematic process necessary to account for the geochemical progression culminating in the formation of porphyry copper deposits. The application to the Ray and Christmas districts is especially satisfactory, in which there is a clear progression from early, dry, barren intrusions, to intermediate age subproductive intrusions, and finally to late-stage, volatile-rich, productive stocks; this is clearly the sequence of events that any of the aforementioned models would predict. This is especially important because there is no evidence 142 supporting distinct source regions for productive and barren intrusions, notwithstanding the few possible exceptions noted above, such as the Elephant Head stock. The process of hybridization might also explain why productive igneous systems in Arizona are usually longer-lived and have a much more complex magmatic history than barren systems. The igneous systems that include porphyry copper deposits usually contain more numerous pulses of magma over a longer time than barrell systems. The separate, barren systems are in many cases single, although sometimes voluminous, pulses of magma. Long-lived systems reflect long term magma generation at depth. Such persistence in a given column of crust may reflect long term hybridization that maintains the ability to generate magmas. If hybridization is necessary to the process of porphyry copper genesis, then the long-lived systems are more likely to have experienced it to a greater degree. Similarly, if assimilation of hybridized crust is important then long-lived systems, in which the thermal barriors to the assimilation of crust abate, are more likely to be favorably affected. Likewise, long-lived heat flux into the lower crust might be necessary to push melting isotherms upward into appropriate, hydrous cnlSt. Simple igneous systems may have been insufficiently hybridized in their source region for long-lived magmatic or mineralizing activity or they lacked the thermal capacity to assimilate a sufficient amount of hydrous, amphibolitic crust. Source of Metals in Porphyry Copper Deposits. Although each of the three mechanisms discussed above might provide the volatiles necessary for the magma to concentrate metals into an ore deposit, the ultimate source of the metals in porphyry copper deposits remains poorly constrained. The hypothesized transfer of fluids, volatiles, and perhaps some other melt components from the slab to the wedge to the crust allows the metals to be picked up anywhere along the way. The coherence of the assemblage of metals in porphyry ore deposits to the crustal environment in which they occur (Titley and Anthony, 1989) is strong circumstantial evidence for a crustal source. The regional distributions of Au and Ag in ore deposits of this region mimic the patterns of the crustal provinces (Titley, 1987 and 1991), as does the Pb isotope signature of ore galenas (Bouse et aI., 1990a). Furthermore, the metal assemblage of porphyry deposits, in general, depends strongly on the type of crust which they overlie (Titley and Beane, 1981). This fits with the models above in 143 which the productive melts are generated predominantly from the crust; their metal assemblages mimic patterns in the crust, and imply that the metals are probably also derived predominantly from the crust. Unfortunately, the evidence remains largely circumstantial. An exception to the crustal inheritance of metal signatures might be represented by the productive porphyry at Dos Pobres. It has an eNd value of -3.2, and the associated ore deposit has very high Au and low Mo. Porphyry systems with high Au contents are most common in oceanic island arcs where no ancient basement occurs (Titley and Beane, 1981) and in alkaline magmatic systems (Titley, 1989); both are cases in which greater or different types of mantle input are suspected. The Dos Pobres deposit may be reflecting a greater mantle input. The adjacent Lone Star deposit has very low Au, high Mo, and a fNdr value of -8.7, all of which are typical of deposits overlying ancient continental crust. Metal sources may, therfore, be complex even on a local scale. Laramide Metallogenesis Several factors probably have to act in concert to impart upon a magma the ability to form a porphyry copper deposit. An increasing body of evidence implies that, regardless of the ultimate source of metals, typical calc-alkaline magmas probably contain sufficient base metals to generate a porphyry copper deposit, but whether or not they do so depends on their ability to efficiently extract and concentrate the metals (Candela and Holland, 1986; Candela, 1989; Cline and Bodnar, 1991), i.e. process is more important than source. Extraction efficiency depends on several factors. Of particular importance is that the volatile content of the magmas, especially of water, must be sufficient to effect removal of metals from the melt and to fracture the cooling rind and the wall rocks of the intrusion to permit egress of mineralizing fluids. Water and other volatiles may be acquired systematically through the models described above. The subsequent differentiation history must affect the absolute degree of volatile saturation and must, therefore, also affect the efficiency of \ removal of base metals into evolved aqueous fluids (Candela and Holland, 1986). Early water saturation promotes a higher copper extraction efficiency whereas later saturation promotes a higher molydenum extraction efficiency (Candela and Holland, 1986). The timing of water saturation is a function of pressure and oxidation state in these magmas, with deeper intrusions evolving fluids later 144 in their crystallization history, favoring Mo concentration, and shallow intrusions saturating in water earlier, favoring Cu mineralization. More highly oxidized melts promote efficient removal of both Cu and Mo into evolved aqueous fluids (Candela, 1990); each of the models of evolution in Laramide magmatic systems are compatible with the formation of progressively more oxidized melts that eventually may cause f~ to be buffered at high levels by water (Anthony, 1986). The generation of porphyry copper deposits requires that the most favorable of each of these factors must come together in a single system; the proposed models might facilitate this. The ability of a magma to accomplish this favorable melding of events may very well be determined by the processes that affect the source region of the mineralizing plutons. In conclusion, this study contributes to a growing body of knowledge that suggests that mineralization related to granitoid genesis is more strongly related to process than to source. However, processes acting upon the source region or upon the magmas during their ascent through the crust may be as or more important than processes in the immediate environment of ore deposition. The capability of a granitoid to effectively concentrate metals into an ore deposit via processes operating in the upper crust may ultimately depend on characteristics inherited from or dependent upon the evolution of the source region in the lower crust over time. The process is likely to be a systematic one, most plausibly related to the generative mechanisms of melts in the magmatic arc environment such that it can transcend local variations in crustal composition between magmatic arcs. Generally applicable, systematic processes such as crustal hybridization, progressive assimilation, or migration of the melting front through layered crust therefore gain greater validity and can account both for the observed trends in geochemical data and for the evolution of magmatic systems toward porphyry copper mineralization. This study has shown that productive magmas are not unique and distinct from their barren brethern but rather they represent a certain culminating stage of evolution of magmatic processes as it affects a given column of crust. The limited data, as discussed above, from porphyry-mineralized provinces other than southwestern North America also suggest that whichever process imparts the systematic behavior to these magmatic systems it may be more broadly applicable to porphyry mineralization generally, but additional comprehensive studies 145 coupling isotopic and trace element studies are needed to establish the connection, and its details, more strongly. 146 CHAPTER 6 CONCLUSIONS Some of the principal observations of this geochemical examination of Laramide magmatism and metallogenesis in Arizona can be summarized as follows: 1) The Sm-Nd and Rb-Sr isotope systems demonstrate that Proterozoic, lower continental crust is the dominant component of Laramide magmas. The stimulus for crustal melting was the emplacement of basic, mantle-derived magmas into the lower crust. Early volcanic rocks penetrated a brittle, coo~ locally extensional crust and may retain evidence of a mantle component. Subsequent plutons are predominantly products of crustal anatexis. 2) Regional differences in the Sm-Nd and Rb-Sr isotopic composition of the Proterozoic crust are reflected in Laramide magmas. The isotopic patterns correspond to Northwest, Southeast, and South Provinces which closely follow the patterns of crustal provinces suggested by prior geologic, geochemical, and isotopic studies. Lead isotope data on Laramide igneous rocks (Bouse et aI., 199Ob; Lang et al., 1990) fully support the subdivisions based on Sm-Nd and Rb-Sr isotopes. The isotopic provinciality arises from geochemically distinct blocks of crust. The Northwest Province attained its different isotopic character as a consequence of the incorporation of a early Proterozoic or Archean component during its formation at 1.80a; the South and Southeast Provinces apparently did not receive a comparable input. 3) Trace element behavior in the Laramide igneous rocks also varies according to which crustal province the rocks occur in. In a fashion analogous to the behavior of isotopes, the trace element provinciality probably reflects different compositions of crust in each province. 147 4) There is no apparent distinction in the isotope geochemistry of barren and productive plutons or systems of Laramide age in Arizona. The range of isotopic compositions for the productive stocks is similar to that of the Laramide stocks as a whole. On the district scale, productive stocks have a very siight tendency to be among the more isotopically evolved rocks, but numerous exceptions to this pattern preclude its usefulness as a discriminating generalization. 5) Some trace elements behave differently between the productive and barren stocks. The concentration of some base metals, the HFSE, and the REE is lower in productive stocks than in barren. 6) The REE follow smooth trends with time in most igneous systems. As magmatism in a district progresses, the stocks display decreasing total REE abundances with depletions of the HREE more marked than for the LREE, and the Eu anomalies become increasingly less negative and may even attain positive values in late stage stocks. Productive plutons occur late in the magmatic sequence and have REE proflles compatible with this position. The behavior of the REE demonstrates that a systematic process has operated on Laramide magmatic systems. 7) Three models can account for most aspects of the geochemical evolution of Laramide magmatic centers and their associated metal deposits, including: 1) metasomatism of the lower crust by fluids derived from either the descending slab or the mantle wedge, 2) progressively greater assimilation of hydrous crust into mantle-derived, basic magmas as the crust became increasingly warm, and 3) upward migration of the crustal melting front in response to a progressively warming crust. It is not yet possible to distinguish the relative roles played by each process, but each one provides a means to maintain prolonged crustal anatexis in a restricted column of crust, to generate the systematic evolution in REE geochemistry, to effect the depletions in base metals and HFSE that occur in late stage, usually productive stocks, and provide the level of volatile concentration and oxidation state necessary for the generation of porphyry copper deposits. 148 APPENDIX A SAMPLE WCATIONS Information necessary for accurately locating the samples for which data are reported in this study is listed in Table A.I. The locations of individual sampling sites for each system are shown on the generalized geology maps found in Figures 2.4. to 2.7 in Chapter 2. Each sample designation encodes several points of information. The letter(s) indicate the magmatic system from which the sample was obtained: C, Copper Creek; SF, Safford; R, Ray; CH, Christmas; S, Sierrita; SR, Santa Rita Mountains; T, Tombstone; CK, Crown King; CB, Copper Basin; B, Bagdad; D, Diamond Joe. The fIrst number after the letter indicates the relative position that the sampled igneous unit occupies in the magmatic sequence in the district, e.g., 1 is the fIrst pulse of magma and 6 is paragenetically much later. If this number is followed by a letter, e.g., B2a, it indicates that more than one rock type occupies a similar, indistinguishable temporal position in the district. The second number indicates the sample number of the unit of interest. For example, the sample B3b2 is the identiller of sample number 2 of a rock from the Bagdad district that was emplaced during the third pulse of magmatism in the district, but which the b indicates is also occupied by other rock types. In this particular instance, the sample is sample 2 from the Southwest Stock in the Bagdad district which was emplaced at a time indistinguishable from the Bagdad and Blue Mountain Stocks. Table A.1. Sample locations. SAHPlE UNIT QUADRANGLE TOYNSHIP/RANGE/SEC LONGITUDE LATITUDE C(JIHENTS B21 rhyol i te dike Bagdad T1SNR9YSec31NE1/4SE1/4 113013'S9" 34035'40" road 200111 S of conveyor belt B22 rhyol I te dlka Bllgdad T14NR9YSec7UE1/4S~I/4NEli4 113014'15" 34034'10" saddle above Mamnoth ~ash B31 Blue Hountain Stk Big Shipp Htn T14.SNRBIISec28SE1J4S~1J4S~1J4 1130 6'22" 34036'21" from stream bed on pediment B32 Blue Hountaln Stk Big Shipp Mtn T14.SNRBIISec33SIII/4NII1J4NIII/4 1130 6'33" 34036'04" Itrellm bed nellr I1IIIroln of stock B33 Blue Hountaln Stk Big Shipp Htn T14.5NRBIISec32NII1J4SE1J4NE1J4 1130 6'42" 34035'56" fine oralned border phase B34 Blue Hountoln Stk Big Shipp Htn T14.5NRBIISec2BSII1J4SIIIJ4NE1J4 1130 6'05" 34036'46" collected In Blue CDnyon B1S Blue Hountaln Stk Big Shipp Htn TI4.5NRBIISec2BNIII/4SE1/4NE1/4 1130 5'44" 34036'53" do B36 Blue Hountain Stk Big Shipp Mtn T14.5NR8I1Sec32NIII/4SEI/4NE1/4 1130 6'42n 34036'5B" saddle above Sycamore lIash, near margin B3al Bagdad Stock Big Shipp Htn TI4NR9YSec4SI11J4NE1J4 113012'13" 34035' 2" from pit B3bl Southwest Stock Bagdad T14NR9YSec7NE1/4S~I/4Nlll/4 113014'45" 34034'16" road to Grayback Htns B3b2 Southwest Stock Bagdad T14NR9YSec7NIII/4SII1/4NIl1/4 113014'54" 34034'14" road to Grllyback Htns B3b3 Southwest Stock Bagdad TI4NR9YSec7N~1J4NE1/4 113014'14" 34034'15" road to Grayback Htns B3b4 Southwest Stock Grayback Htns TI4NRI0IISecI2SE1J4NII1J4NE1J4 113015'09" 34034'2S" dozer cut above Hammoth Uash dam B41 diorite porph dike Bagdad T14NR9YSecBSIII/4NII1J4 113013'40" 34034' 9" collected at Copper ICing mine B42 diorite porph dike Bagdad TI4NR9wSecBNlll/4Nlll/4Nlll/4 113013'49" 34034' 6" 2S0m SII of Copper ICing mine BSI porph qtz monzonite Bagdad TI4NR9YSec4Nlll/4NU1/4 113012'51" 34035'17" from pit; mine coords 97300E x 100500N B52 porph qtz monzonite Bagdad TI4NR9YSecSNE1J4 113013' 5" 34035' 17" from pit; mine coords 96250E x 100400N B61 granite porphyry dike Bagdad TI4NR9YSec4NE1/4NU1/4 113012'28" 34035' lB" core from 245m; coords 98300Exl02000N ======a===_=s:=c:= ••c======a======•• =••• a ••••• : •••• cs.======.====:======s======:======T11 Bronco Volcanics Lewla Spra T21SR21ESecI2Nlll/4HU1/4 110010' IS" 31037'30" RR cut S of Chari eaton 112 Bronco Volcanics fairbank T20SR21ESec36S1/2NE1/4 1100 11'30" 31039' 750m SE of [harle.ton Hlne Tt3 Bronco Volcanics fairbank T20SR21ESec2SII1/2SE1/4 11009' 31039'30" 750m NNE of Charleston Hine T14 Bronco Volcanics Fairbank 1 121 Schleffelln Gd lcabstone TI9SR22ESec33SE1/4SII1/4 1100 6'30" 31044' near Schleffelln Monument 122 Schleffelln Gd Lewis Springs T21SR21ESecI2NE1/4NE1/4 110010' 31037' 10" RR cut S of Chllrleston T23 Schleffelln Gd Lewis Springs T21SR21ESec12SSS 110010' 31037'12" RR cut S of Charleston T24 Schleffelln Gd Lewis Springs T21SR21ESec12SSS 110010' 31037' 12" RR cut S of Chllrleston 125 Schleffel In Gd Lewis Springs 121SR21ESec12S~I/4N~I/4 110010' 31037'15" RR cut S of Charleston 12nl Unci e Snm luff I orrbs tone 120SR22ESec20N~I/4NE1/4 1100 7' 31041'30" S of Uncle Sam Hili 12112 IIncle SWlI luff Fairbank 120SR22ESec6ESS 1100 8' 31043'30" II of Three Brothers nlll T2a3 Uncle Sam Tuff Fairbank 120SR21ESeclBSlll/4SU1/4 110015' 31041'30" 750m S of Babocomari River T2a5 Uncle Sam Tuff loaDstone T20SR22ESec22NSS 1100 5' 31041'30" old aqueduct below Ajax Hill ..... ~ T2a6 Uncle Sam Tuff torrbstone T20SR22ESec22NE1/4SII1/4 11005'30" 31039'30" top of hill II of Ajax Hill \0 Table A.I. continued. SAMPLE UNIT QUADRANGLE TDUNSHIP/RANGE/SEC LONGITUDE LATITUDE CCHIENTS 131 Rhyodacite Tocrbstone TZOSRZZESec2ZNE1/4SU1/4 1100 5' 31041' saddle on Y Iide of Ajax Hill 132 Rhyodacite Tocrbstone T20SR22ESecZ2NEI/4SU1/4 lIDo 5' 31041' saddle on Wside of Ajax Hill 141 Tocrbstone Rhyolite Tocrbstone TZOSR22ESec36NE1/4 150m Y of AI 80 142 Tocrbstone Rhyolite Tonbstone T20SRZZESec36NE1/4 750m Y of Al 80 143 Tocrbstone Rhyolite Tarbstone TZOSRZ3ESee31NE1/4 1100 1'35" 31039'18" roadcut on Al 80 T" Tocrbstone Rhyolite Tocrbs tone TZOSR23ESec31NE1/4 1100 1'35" 31039'18- roadcut on Al 80 c======a&=~a~==&a:=&:=c=a======•••s.az= ••• s ••••••=.=::.:c===c=.u=a.:.a: •• = •• ======CHI Williamson Cyn Voles Christmas T4S/RI6E/SECZO/ESS 110043'33" 3304'14" roadcut on Al 77 CHZ Williamson Cyn Voles Christmas T4SR16ESEC3ZSWI/4SEI/4 110043'47" 3302'6" do CHal Hbl Andesite Dike Christmas sample 72AB74 of Koski and Cook (1982) CHll MacDonald Stk Chrlumal T4SRI6ESecI6SE1/4SU1/4 110043' 1" 330 1;'49" road to ChrlltllBl plant CH12 do Christmas T4SRI6ESecI6Wl/ZSUI/4 110043'Z8" 330 4'54" road to Chrlatmas Plant CH14 Granite Basin Stock Christmas sample GB-l of Koski and Cook (1982) RIal Rattler Granodiorite Hot Tamale Pk T3SRI4ESEcorn2Z 110053'40" 3308'53" Troy Ranch aeeeia rd RlaZ Rattler Granodiorite Hot Tamale Pk T3SRI4ESECZ3SW1/4SW1/4 110053'37" 3309'3" Troy Ranch accesl rd Rla3 Rattler Granodiorite Hot Tamale Pk T3SRI4ESECZZNW1/4SE1/4 110054' 3309'30" NW Iida of Troy B•• ln RIa' Rattler Granodiorite Hot Tamale Pk T3SRI4ESECZZNW1/4SE1/4 110054'10" 3309'33" NW side of Troy Balin Rla5 aplite dike Hot Tamale Pk T3SRI4ESECZZSEI/4 110054' 3309'18" NY side of Troy Basin Rla6 rhyodacite dike Hot Tamale Pk T3SRI4ESECZ3SWI/4 110053'3Z" 3309' IS" Troy Ranch access rd RII Tortilla Qtz Diorite . Teacup T3SRI3ESEC34NE1/4NE1/4 110059'51" 3308' ridge Wof Al 111 and S of Granite Mtn R12 Tortilla Qtz Diorite Teacup T3SRI3ESECZ7SEI/4SEI/4 1110 0' 6" 3308'5" do R13 Tortilla Qtz Diorite Teac~ T3SR13ESECZ7SW1/4SE1/4 11100'19" 3308'6" do R14 Tortilla Qtz Diorite Teac~ T3SR13ESee34NW1/4NE1/4 1110 0' 16" 3308'Z" do R15 Tortilla Qtz Diorite Teacup 13SR13ESec36I1SS 110058'5Z" 3307'35" do RZI Teacup Granodiorite Grayback T4SR13ESec30swl/4 11103'47" 3303'Z" 100m E of substation RZZ Teacup Aplite Grayback T4SR1ZESec36NW1/4SE1/4 11104' 19" 330Z'ZO" 1500rn S of substation RZ3 Tt'ocup Apli te Groybock T4SR1ZESecZ4SII1/4NW1/4 11104'53" 3304'8" prominent ridge ESE of Graybock Htn RZa4 hbl andesite dike Grayback T4SR1ZESecZZSW1/4NE1/4 11106'25" 3304'10" lZ00m UNU of windmill In drainage RZ5 Teacup Grenodiorlte Grayback T4SR1ZESecZZSW1/4NE1/4 11106'Z7" 3304' 13" do R26 Teacup Granodiorite Grayback T4SR1ZESec24NE1/4NW1/4 11104'38" 3304'Z4" Zkm E of Grayback Htn R2a7 rhyodacite dike Graybock T4SR1ZESecZ4SU1/4Nlll/4 11104'55" 3304'10" prominent ridge ESE of Grayback Mtn R31 Granite Htn Porphyry Teacup T3SRI3ESec8SU1/4SE1/4 1110 2'20" 33010'"'' roadcut on Al 177 ...... IJ1 R32 Granite Htn Porphyry Teacup T3SRI3ESec19SE1/4SE1/4 1100 3' Z" 330 9' 4" lkm E of Copper Butte a Table A.I. continued. SAHPlE UNIT QUADRANGLE T~SHIP/RANGE/SEC LONGITUDE LATITUDE COMMENTS R33 Granite Htn Porphyry Teacup T3SR13ESec20SSS Ul/2 1110 2'45" 330 9'20" 1500m E of Copper Butte R34 apl He dike Teacup T3SRI3ESecI9ESS 1110 3' 4a 330 9'18" lkm E of Copper Butte R35 Grnnite Htn Porphyry Hot Tamale T3SRI3ESecI4SE1/4NU1/4 110059'32" 33010'22" barren core In RIlY pit CH31 Christmas Stock Christmas T4SR16ESec20SSS 110044' 3303'45" road to Christmas pit CH32 Christmas Stock Christmas sample 0256-148, Koski and Cook (1982) R41 Teapot Htn Porphyry Teacup T3SRI3ESec9SE1/4 1110 I' S" 33010'54" 350m N of Last Turn Hill, Old Ray Rd R42 Teepot Htn Porphyry Teacup T3SRI3ESecI9SE1/4NU1/4 1110 3'30a 33010'50" 500m NNE of Copper Butte R51 late rhyodacite plug Teacup T3SR13ESec19NU1/4 1110 3'37" 330 9'34" 500m NNE of Copper Butte ======8:2 •• :::Z&&==_======Z======011 granodiorite border Gunslght Cyo TI7NRI4USec26NU1/4Sul/4 113044'16" 34049'27" from durp on SE margin of stock 012 granodiorite border Olamomd Joe Pk TI7NRI4USec20NSS-NU1/4 113047'17" 34050'52" wash on NU aide near old workings 013 granodiorite border Olamomd Joe Pk TI7NRI4USec30NE1/4NE1/4 113047'33" 34049'50" near Levisthon mine from olltcrop 014 granodiorite border Olamomd Joe Pk T17NR14USec29SU1/4NU1/4 113047'27" 34049'40" 20m from SU stock margin in wash 021 latite/dacite dikes Olamomd Joe Pk T17NR14USec30NE1/4 113047'43" 34049'52" wash U of Leviathan vein D22 lotlte/doclte dikes Dlemomd Joe Pk TI7NR14USec29SU1/4NU1/4 113047'23" 34049'42" 50m frOO! SU stock morgln In Wllsh 031 qtz monz porphyry Dlamomd Joe Pk T17NRI4USec21NU1/4SE1/4 113046' I" 34050'19" workings at Silvertralls mine 032 qtz monz porphyry Dlamomd Joe Pk TI7NR14USec21SE1/4NU1/4 113046'17" 34050'30" road E of Gunslght saddle 033 qtz monz porphyry Olamomd Joe Pk T17NRI4USec21SE1/4SE1/4 113045'29" 34050'12" saddle SU of 0111_ Joe peak 041 granite dikes Olamomd Joe Pk TI7NRI4USec21S1/2NU1/4 113046'2S" 34050'32" on road E of Gunsight saddle 042 granite dikes Olamomd Joe Pk T17NRI4USec21SU1/4NU1/4 113046'24" 34050'37" above road E of Gunslght saddle D51 qtz porphyry dike Olarnomd Joe Pk TI7NRI4USec21NU1/4SE1/4 113045'35" 34050'21" from NE IIlde of ridge to Dill Joe pellk ••••••• ~ •••• ~= ••••••••••••••••• a ••••••••••• a •••••••• a • ••••••••••••••••••••••••••••••••••••••• c.a ••••••••••••••••••• : ••••••: •••••••••• Cl1 Glory Hole andesite Oak Grove Cyo TBSR1BESec2NU1/4NE1/4 110028'33" 32046' 15" surface IIIImple C12 Glory Hole rhyollts Oak Grovs Cyo T8SRI8ESec2SE1/4NU1/4NU1/4 110028'40" 32046' 16" do C13 Glory Hole IIndeslte Oak Grovs Cyn T8SRI8ESec2SU1/4NU1/4NU1/4 110028' 58" 32046' 14" do C21 Copper Creek Gd Oak Grove Cyo T8SRI8ESecl0NE1/4NEI/4SE1/4 110028'50" 32044'55" ODH NE-5 iI 84';flne gr_ granodiorite C22 topper Creek Gd Rhodes Peak TBSR1BESec14NU1/4 110028'45" 32044'30" DDH 5-14 iI 978m; coarse gr_ granodlorlt C31 pink dacite porphyry Oak Grove Cyn do 110028'50" 32044'55" DDH NE-5 iI 164m C41 dark dacite porphyry Oak Grove Cyo do 110028'50" 32044'55" DDH NE-5 iI 930m C42 dark dacite porphyry Rhodes Peak do do do ODH 5-17 iI 1006m C43 dark dacite porphyry Rhodes Pellk do do do ODH S-17 iI 347m C44 dark dacite porphyry Rhodes Peak do do do ODH SK-l~ 52m ...... U1 C45 dark dacite porphyry Rhodes Peak do do do DOH SK-1 iI SlIm ..... ======:C==2C •• 2: ••• a==c.:c======Table A.I. continued. SAHPLE UNIT QUADRANGLE TOUNSHIP/RANGE/SEC LONGITUDE LAT Ill'DE COHHENTS ------.------SF11 Safford Andesite \/eber Peak T5SR26ESec27S\/I/4NE1/4S\/I/4 109040'10u 32057'28" surface dnp at development shaft " SF12 Safford Andesite \/eber Peak T5SR26ESec27SW1/4SW1/4S\/I/4 109040' 16u 32057' 17" DOH Rl-8 a 77411 SF13 Safford Andesite Lone Star Htn T5SR27ESec31SE1/4SE1/4SE1/4 109036'22u 32056'48" DOH 167 iii 150011 SF14 Safford Andesite \/eber Peak T5SR26ESec27S\/I/4NE1/4S\/I/4 109040'111'" 32057'28" DOH SP/Sl iii 86211 SF15 Safford Andesite \/eber Peak T5SR26ESec33NE1/4SE1/4NE1/4 109040'23" 32056'55" DOH S-18 iii 107111 SF16 Safford Andesite \/eber Peak T5SR26ESec34S\ll/4N\ll/4N\ll/4 109040' 14" 32057' 4" DOH S-2 II 34711 SF17 Safford Andesite Lone Star Htn T5SR27ESec31S\lI/4N\lI/4 109037' 15 u 32057'20" DOH G-l II 457. SF21 lone Star Pluton Lone Star Htn T6SR27ESec6SE1/4S\ll/4SE1/4 109037' 10" 32056'01· DOH 149-A iii 1366111 SF22 lone Star Pluton lone Star Htn T6SR27ESec7NE1/4N\/I/4NE1/4 109037'08" 32055'52" DDH 147 iii 121911 SF23 Lone Star Pluton Lone Star Htn T6SR27ESec7S\ll/4S\ll/4 109037'32- 32055'21u DOH CH-2 iii 373m SF31 Dos Pobres Porphyry \leber Peak T5SR26ESec33SE1/4SE1/4NE1/4 109040'22" 32056'52" DOH U-3 iii 31211 SF32 Dos Pobres Porphyry \/eber Peak T5SR26ESec27S\lI/4N31/4SW1/4 lD9040'21 u 32057'07" DOH Rl-26 a 776m SF33 Dos Pobres Porphyry \leber Peak T5SR26ESec33SE1/4NE1/4HE1/4 109040'23" 32057'01" DOH S5 iii 436m SF34 lone Star Porphyry lone Star Htn T6SR27ESec5NE1/4N\/I/4S\ll/4 109036'20u 32056'22" DOH G-l0 iii 696m SF35 lone Star Porphyry lone Star Htn T6SR27ESec7SE1/4N\ll/4HE1/4 109037'09" 32055'44" DOH G-3 iii 375m SF41 hbl andesite dike \/eber Peak T5SR26ESec27S\ll/4NE1/4S\ll/4 109040'10" 32057'28" DOH SP/S-l a 45711 SF42 Baboon Andesite \leber Peak T5SR26ESec27S\ll/4NE1/4S\ll/4 109040'10u 32057'28" probably large xeno of Safford volc_ SF43 Baboon Andesite lone Star Htn 15SR27ESec32N\ll/4NE1/4NE1/4 109035'22u 32057'36" DOH H-l iii 256m SF44 vent breccia Lone Star Htn T6SR27ESec5S\ll/4S\ll/4N\/I/4 109036'37" 32056'30" DOH G-5 iii 32011 ======z======%======~==.==z==.======z======CB11 border phase diorite \/Ilhol t T13NR3\/Sec20S\/I/4N\/1/4NE1/4 112035'31" 34029'44" DOH 62-34 iil 27311 CB12 border phase diorite \lilhol t TI3NR3\/Sec20S\/I/4S\/I/4NE1/4 112035'29" 34029'30" DOH 48-36 a 30311 CBB border phase diorite \llIhol t T13NR3USec20N\/I/4SE1/4NE1/4 112035'19" 34029'34" DOH 52-44 a 227m CB21 main phase gd \/Ilhol t TI3NR3USec20N\/I/4NE1/4SE1/4 112035'12" 34029'20" DOH 38-50 a 245 to 38Dra CB22 main phase qtz monz \/ilholt TI3NR3USec20S\/I/4NE1/~SE1/4 112035'15u 34029'16" DOH 36-48 a 183 to 26Dra CB23 main phase gd \lilhoi t TI3NR3USec2IN\/1/4SE1/4N\/I/4 112034'41 u 34029'34" DOH 52-84 iii 27Dra CB24 main phase 9d \lilhoi t T13NR3\/Sec20N\/I/4SE1/4NE1/4 112035'19" 34029'34" DOH 52-44 iii 22Dra CB31 older qtz latlte par \/ilhol t TI3NR3USec21SU1/4S\/I/4N\/I/4 112034'59" 34029'29" DOH 48-60 iii 183m CB41 younger qlZ I nt par \/ilhol t TI3NR3USec21N\/I/4S\/I/4N\ll/4 112035'04" 34029'34" DOH 52-56 iii 255m CB51 apl i te \Ii Ihol t 113NR3\1Sec20S\/I/4S\/I/4NE1/4 112035'29" 34029'30" DOH 48-36 iii 123m ======:======:======:=~======.&c=~.zs.==z===.=%======c==c======CICI Crown ICing Stock Crown ICing Tl0HR1U Unsurveyed 112020'13· 34012'27" qUllrry iii 5m depth; Ipl from B. Clements ..... U1 ======C=====Z2a======N Table A.I. continued. SAMPLE UNIT QUADRANGLE lOUNSHIP/RANGE/SEC LONGlTlJOE LAT lTUDE COIMENTS PBBA-1 Bridle Fm basalt Bagdad T14NR9USec8NE1/4SU1/4NU1/4 113013'56" 34034'10" near Copper King mine PBGS-1 gabbrolc intrusion Grayback "tns T14NRI0USec1SE1/4SU1/4SE1J4 113015'13" 34034'35" Burro Creek PCA-1 Cerbat anP1lbollte Chloride 124NR182Sec34SE1/4NU1/4SE1/4 114011'170 35025'19" near Elkhart mine PCA-2 cerbat anP1 I boll te Chloride T24NR182Sec34NE1/4SE1/4NE1/4 114010'590 35025'40" near Dardanelles mine PCGN·l Cerbat gneiss Chloride 124NR182Sec34NE1/4SE1/4NE1I4 114010'56" 35025'44" do PJG-l Goddes Basal t, Jerome sample collected by 5_ R_ Tltley POCA-1 Dos Cubezas amphlb Bowie "tn North114SR28ESec28SE1/4SE1/4SU1/4 109029'33" 32010'51" noar Silverminea IIlne PLDA-l Little Dragoons amph Dragoon T15SR223Sec17 110007' 32007'30" NU of Seven Dash Ranch PLDA-2 Little Dragoons aap, Dragoon T15SR223Sec17 110007' 32007'30" NU of Seven Dash Ranch PLDA-3 Little Dragoons aap, Dragoon T15SR223Sec17 110007' 32c07'30" NU of Seven Dash Ranch PRA228 little Rlncons aap, sample provided by K. Condie ======cz======:=c======--====== ..... Ln W 154 APPENDIXB COMPILATION OF NEW AND EXISTING RADIOMElRIC DATES Five new potassium-argon radiometric dates were obtained during this study and the results are listed in Table B.I. Three determinations dated the diorite porphyry dikes, the Blue Mountain stock and the Southwest stock from the Bagdad system and two established the age of the granodiorite and quartz monzonite porphyry phases of the Diamond Joe stock. Table B.I1 is a compilation of the published radiometric dates for each magmatic center examined in this study. The decay constants used for each date are listed. Most data utilize currently accepted decay constants; those few that do not have not been recalulated. 155 Tu,le B.:I. Data for new K-Ar dates. Unit Hinel"al S8IIOle Latitude Longiwae K Radiogenic Atmes. Date (wt X) AI" (pmlg) AI" (X) Oiol"ite porphyry dike Copper King mine, Bagdld biotite B42 34034'06M 113013'49. 6.79 903.4 5.4 75.2 ~ 1.7 Southwest Stock, Bagdld biotite 83b1 34034' 16M 113014' 45M 6.249 866.3 10.9 78.3 ~ 1.8 Blue Hountain Stock, Bagdad biotite 832 34036'04· 113006'33· 7.077 954.3 4.6 76.2 ~ 1.7 DfBllOnd Joe, granodiorite border pilale biotite 031 34050'23" 113045'52" 7.054 897.8 20.1 n ~ 1.7 Diamond Joe, quartz monzoni te porflllYry biotite 014 34049'30" 113047'27" 7.435 947.8 6.1 n.1 ~ 1.6 156 Table B.II. compilation of published radiometric dates from some Laramide maqmatic centers in Arizona. Description Age Crown King Stock 64 ± ? bt? ? 1 DIAMOND JOE STOCK granodiorite border phase 74.7 ± 2.7 ? ? 10 granodiorite border phase 72.1 ± 1. 6 bt o porphyritic quartz monzonite 71.9 ± 1.5 bt? ? 10 quartz monzonite porphyry 68.9 ± 2.6 bt? ? 10 quartz monzonite porphyry 72 ± 1. 7 bt o BAGDAD AREA Southwest stock 78.3 ± 1.8 bt o Blue Mountain Stock 76.2 ± 1. 7 bt o diorite porphyry dike 75.2 ± 1. 7 bt o alteration date in Bagdad Stock 70.9 ± 2.3 bt 3 9 RAY AND CHRISTMAS AREAS WCV - hornblende andesite dike 76.2 ± 1.9 hbl 1 17 WCV - slightly altered tuff 76.2 ± 2.3 hbl 1 17 WCV - hornblende andesite dike 81.7 ± 2.4 hbl 1 17 WCV - andesitic crystal tuff 75.6 ± 1.4 bt 5 11 WCV hornblende basalt dike 79 • 3 ± 1. 4 hbl 5 11 WCV stock cutting flows 81.7 ± 1.9 hbl 5 11 Tortilla Quartz Diorite 70.3 ± 1. 7 bt 1 22 Tortilla Quartz Diorite 72.4 ± 1. 4 bt 1 2 Tortilla Quartz Diorite 73.1 ± 2.1 bt 1 2 Tortilla Quartz Diorite 73.3 ± 1.4 bt 1 2 Tortilla Quartz Diorite 82 ± 1.4 bt 1 2 Tortilla Quartz Diorite 69.8 ± 2.5 zir IT 3 Tortilla Quartz Diorite 69.3 ± 6.1 ap IT .3 Tortilla Quartz Diorite 69.8 ± 4.1 zir IT 3 Tortilla Quartz Diorite 72.4 ± 8.6 ap IT 3 Rattler Granodiorite 70.2 ± 1.4 bt 1 2 Rattler - equigranular hbl gd 71.1 ± 3.2 bt 3 9 Rattler - porphyritic bt-hbl gd 71.5 ± 1. 4 bt 1 2 Rattler - porphyritic bt-hbl gd 76.3 ± 1.5 hbl 1 2 Rattler Granodiorite 68.4 ± 2.2 ti IT 3 Rattler Granodiorite 68.5 ± 4.2 ap IT 3 rhyodacite dike cutting Rattler 71.5 ± 1. 4 bt 1 2 MacDonald Stock 69.8 ± 2.1 hbl 1 17 Granite Basin Laccolith 72.3 ± 2.2 hbl 1 17 qtz monz dike cutting Teacup 63.1 ± 1.3 bt 3 8 Teacup Granodiorite - Teacup lobe 62.9 ± 1. 3 bt 3 8 Teacup Granodiorite - Teacup lobe 61. 4 ± 3.2 gt IT 3 Teacup Granodiorite - Teacup lobe 69.7 ± 6.2 WR RbSr 4 Teacup Granodiorite - Box 0 lobe 66.7 ± 2.5 musc 7 4 Alteration in Christmas Stock 62.5 ± 1.6 ser 1 17 Potassic alteration, Christmas 62.8 ± 1. 6 bt 1 17 Christmas stock 64 ± 2.6 bt 1 5 157 Table B.II. continued. Description Age Min K's Ref Granite Mountain Porphyry 61 ± 1. 2 bt 1 2 Granite Mountain Porphyry 61 ± loS bt 1 16 Granite Mountain Porphyry 64.6 ± 2.2 bt 1 2,5 Granite Mountain Porphyry 61.5 ± ? bt ? 20 Granite Mountain Porphyry 61 ± 2.1 ti FT 3 Granite Mountain Porphyry 70 ± 10 bt RbSr 27 Granite Mountain Porphyry 61 ± 9 bt RbSr 27 Alteration at Ray 66.8 ± 1.1 bt 1 2 Alteration at Ray 67.3 ± 1.1 bt 1 2 apatite reset by alteration, Ray 60 ± 6 ap FT 3 Teapot Mountain Porphyry 64.6 ± 0.7 or 1 2 rhyodaci~e dike cutting TMP 63.7 ± 1.2 bt 1 2 TOMBSTONE AREA Schieffelin Granodiorite 76.3 ± 1. 8 bt 1 14 Schieffelin Granodiorite 76 ± 3 bt 1 5,15 Uncle Sam porphyry Tuff 73.5 ± 2.S bt 1 15 Tombstone Rhyolite 66.6 ± 1. 6 bt 1 14 Tombstone Rhyolite 66 ± 3 bt 1 5,15 Tombstone Rhyolite 65.1 ± 1.6 sani 1 14 Alteration at Charleston Pb mine 74.4 ± 3 ser lS Alteration in contention dike 72 ± ? ? lS SANTA RITA MOUNTAINS Salero Formation - welded tuff 74.3 ± 3.3 bt 1 15 Corona Stock 75.5 ± 2.7 bt 1 15 Corona Stock 75.3 ± 2.9 bt 1 15 Empire Stock 71.9 ± 2.5 bt 1 15 Josephine Canyon Diorite 6S.7 ± 3 bt 1 15 Madera Canyon Granodiorite 67.9 ± 2.1 bt 3 9 Elephant Head Quartz Monzonite 70.8 ± 2.9 bt 1 15 Elephant Head Quartz Monzonite 69.9 ± 3 bt 1 15 Greaterville Intrusives - gd 53.3 ± 2 bt 1 15 Greaterville Intrusives - gd 54.S ± 2 bt 1 15 Greaterville Intrusives - qlp 55.2 ± 2 bt 1 15 Greaterville Intrusives - qlp 57 ± 2.3 bt 1 15 Greaterville Intrusives - qlp 57.1 ± 2.1 bt 1 15 Greaterville Intrusives - qlp 57.6 ± 2.1 bt 1 15 COPPER BASIN Border phase 75.5 ± 1.6 bt 1 23 Main Phase granodiorite 64 ± ? bt ? 24 Younger Quartz Latite Porphyry 72.S ± 1.5 bt 1 23 Younger Quar~z Latite Porphyry 72.9 ± 1. 6 hbl 1 23 Alteration in granodiorite 72.6 ± 1.5 ser 1 23 COPPER CREEK Gloryhole Volcanics 62.8 ± 1.3 wr 1 22 153 Table B.II. continued. Description Age Min K's Ref ------Copper Creek Granodiorite 69.7 ± ? bt 1 5 Copper Creek Granodiorite 66 ± 2 bt 25 copper Creek Granodiorite 65.8 ± 1.6 bt 1 22 Pink Dacite porphyry 60.5 ± 1.5 bt 25 Dark Dacite porphyry 52.5 ± 0.5 bt 25 SAFFORD DISTRICT Lone Star Pluton 69.8 ± 2.7 bt ? 26 Lone Star Pluton 67 ± ? ? ? 26 Lone Star Pluton 58 ± ? ? ? 20 Lone Star Pluton 60 ± ? ? ? 26 Lone star Pluton 68.8 ± 2.5 bt ? 19 San Juan Stock 58 ± ? ? ? 29 Altera~ion in Sol stock 67.5 ± 2.6 ser ? 28 Sol Diorite Porphyry 60 ± 2.5 bt ? 28 Productive Porphyry Dikes 52.2 ± 2 ? ? 26 Productive Porphyry Dikes 47.8 ± 1.8 ? ? 26 Lone Star Productive Porphyry 62.4 ± ? ? ? 9 alteration 56.9 ± 2.2 bt K 26 alteration 53 ± ? ser ? 20 = 'Abbreviations: WR, whole rock: bt, biotite: ser, sericite: hbl, hornblende: bt, garnet: ti, titanite; ap, apatite: or, orthoclase: zir, zircon: san, sanidine. 'Decay Constants }..·10·'O '\,.10'" .OK/K·l0" 1 0.581 4.962 1.167 3 0.589 4.760 1.180 5 0.575 4.905 1.180 FT Fission Track Age RbSr Rubidium Strontium Age Krue Kreuger Labs, no A reported 'References o This study 16 McDowell (1971) 1 Ball (1982) 17 McKee and Koski (1981) 2 Banks et ale (1972) 18 Newell (1974) 3 Banks and Stuckless (1973) 19 Reynolds et ale (1985) 4 Bradfish (1979) 20 Rose and Cook (1966) 5 creasey and Kistler (1962) 21 Shafiqullah and Langlois 6 Damon (1970) (1978) 7 Damon et alp (1964) 22 Shafiqullah et ale (1980) 8 Damon et ale (1970) 23 Christman (1978) 9 Damon and Mauger (1966) 24 Anderson (1968) 10 Gerla (1983) 25 Guthrie and Moore (1978) 11 Keith (1977) 26 Langton and Williams 12 Koski and Cook (1982) (1982) 13 Livingston at alp (1967) 27 Moorbath et ale (1967) 14 Marvin and Cole (1978) 28 Yarter (1981) 15 Marvin et ale (1973) 29 Robinson and Cook (1966) 159 APPENDIXC SAMPLE PREPARATION AND ANALYflCAL TECHNIQUES Sample Collection and Preparation The freshest available material of each igneous unit was collected. Samples were obtained both from the surface and from diamond drill core. Weathered outcrop was avoided to the extent possible. The size of samples taken in the field was 7 to 25kg, and drill core samples weighed between 1 and 2.0kg. The author personally collected the majority of the 117 samples analyzed during this study, with the following exceptions. Eight core samples from the Copper Creek system were provided by James O. Guthrie. Four core samples from Copper Basin and three samples from the Saf"ord system were provided by Mr. Mike Palowski of the Phelps Dodge Corporation. Dr. Spencer R. Titley provided a sample of Precambrian Gaddes basalt from the Jerome district. Three samples from the Christmas system were provided by Dr. Randolph Koski. The sample of Crown King granodiorite was collected by Mr. Brooke Clements. A sample of Precambrian amphibolite from the Little Rincon Mountains was provided by Dr. Kent Condie. The samples were screened for alteration and weathering effects by thin section petrography prior to processing. Samples that were found to be suitably free of secondary effects were then trimmed to remove original surfaces. The nature of magmatic-hydrothermal systems associated with porphyry copper deposits made hydrothermal alteration unavoidable in some cases; in such cases the samples that showed the least effects of hydrothermal alteration were collected and the veins and their alteration selvedges were selectively removed by careful sawing. Sawn samples were washed in an organic detergent and cleaned ultrasonically to remove cutting oils. One to six kilograms of sample were retained for further processing. Samples were wrapped in heavy bleached canvas and broken with a hammer to less than 2.5cm, then this material was crushed to minus O.25cm in an Ak03 lined jaw crusher. A 300g split was then removed, rinsed briefly in dilute HCI, and rinsed thoroughly with distilled water. The samples were powdered to -200 mesh in an Ak 03 -lined mill. 160 The mill was thoroughly cleaned between samples by scrubbing with a hard plastic brush followed by powdering of pure vein quartz and then repetition of the scrubbing procedure. Analytical Tecbniques for Isotopic Measurements Rock powders were dissolved in HF-HN03 in high-pressure bombs at 16d'C for seven days, after preliminary dissolution of major minerals by HF-HN03 in an open beaker on a hotplate. Sample solutions were treated with HCI04 and HCI prior to passing through ion exchange resin. The chemical separations were made by eluting the sample through AGSOW-X12 ion exchange resin in 8.9 ml quartz columns with 2.5M HCI to obtain Rb, Sr, and bulk REE fractions. The separation of Sm and Nd fractions was effected using hydrogen di-2-ethylhexyl phosphate (HDEHP) adsorbed onto PTFE powder in 1.7 ml quartz ion exchange columns using 0.18M HCI as eluent for Nd and O.SM HCl as eluent for Sm. All isotopic measurements were made on a fully automated VG3S4 thermal ionization mass spectrometer with five collectors. The Sm and Nd were loaded with 2.5M HCI onto two Ta side maments and ionized with a Re center mament. Strontium was loaded directly onto a Ta center mament, and Rb was loaded onto the side flIament of a two Ta flIament configuration; loading was accomplished via Ha P04 • The concentrations of Sm, Nd, Sr, and Rb were measured by isotope dilution. Details of the analytical procedures, spike composition, data reduction techniques and results on standard analyses may be found in Patchett and Ruiz (1987). Analyses of the LaJolla Nd standard and the NBS-987 Sr standard during the course of this study are listed in Table C.I. Table C.I1 lists the results of two replicate analyses. Reproducibility of eNd values and the 147 Smt44 Nd ratio was 0.3 and 0.6 e units and 0.19 and 0.37 percent, respectively, for the replicates. Analytical Techniques for Trace Element Analysis Trace element analyses were performed on a VG Instruments Plasmaquad, which couples an inductively coupled plasma source to a quadrupole mass spectrometer for analysis. Approximately 250mg of sample powder were brought up in HF-HN03 and evaporated to dryness 161 for preliminary dissolution of silicates. This was again brought up in HF-HNOa and digested in sealed teflon bombs for seven days at 15cPC. After evaporation to dryness most samples were treated with HCI04 , dried, treated with HCI, dried, brought up in HCI, and left overnight in teflon bombs at 15cP C. In the later stages of the study, samples were left covered overnight on a hot plate in a solution of HCI and H3 BOa' and dried the next day. By either technique the sample was brought up in 5% HCI for analysis. The concentrations of elements were determined by comparison to calibration curves. Curves were constructed for every clement of interest during each sequence of analytical runs by measuring between four and six standard solutions with concentrations between 50 and 1000ppb. The calibration standards were prepared from commercial certified standard solutions available from SPEX Corporation. Solutions containing 250ppm each of Re and In were added to the samples as a concentration spike that was used to normalize the raw data. The accuracy and precision of the analyses were assessed by measurements of USGS rock powder standards W-2 (Centerville diabase), SCo-l (Cody shale), and RGM-l (Glass Mountain Rhyolite). These standards were analyzed with each batch of samples. Table c.m demonstrates that most elements have accuracies within 10 percent of accepted values and 20m precisions that arc better than five percent. A few elements had less accurate and precise results, usually measuring concentrations that were higher than accepted values. These discrepencies probably result from the formation of oxide species in the plasma, although disagreement and uncertainty about the actual values for some of the elements in the reference standards may also contribute. Discussions of oxide interferences may be found in Jenner et aI. (1990) and Longerich et aI. (1990). The results obtained on standard W-2 during this study are in excellent agreement with the results reported by Jenner et aI. (1990). The concentrations of Nd, Sm, Rb, and Sr obtained by isotope dilution and by ICP-MS are compared in Table C.IV and on Figure C.1. In general, the data lie within 10 percent of the X = Y line, although CNd and CSm are consistently somewhat higher by the isotope dilution method. 162 The results on USGS standards (Table C.III) also indicate that the ICP-MS method measures the light rare earth elements a few percent below their accepted values. Whole Rock Analysis Whole rock analyses for the major element oxides, sulfur, chlorine, and fluorine were performed by the commercial laboratories of Bondar-Clegg, Inc., and Skyline Labs, Inc. Major oxide analyses utilized both ICP and DCP emission spectroscopy, following either borate fusion or digestion in HF. Chlorine was analyzed by turbidimetric methods. Fluorine was determined by ion specific electrode techniques following potassium hydroxide fusion. Sulfur analyses were obtained with a Leco apparatus. Water and loss on ignition were determined gravimetrically. Ferrous iron was measured by titration. 163 Table C.I. Analytical results on the LaJolla Nd and the NBS-987 Sr isotope standards. NBS-987 2sigma LaJolla 2sigma 0.710229 10 0.511884 9 0.710257 10 0.511866 13 0.710259 13 0.511847 7 0.710212 10 0.511859 6 0.710224 9 0.511854 6 0.710252 14 0.511879 9 0.710222 9 0.511857 6 0.710229 11 0.511861 8 0.710234 10 0.511854 9 0.710244 13 0.51186 8 0.710222 14 0.511852 6 0.710238 18 0.511871 6 0.710237 10 0.511851 7 0.710226 10 0.511856 11 0.511867 9 0.511859 6 0.511853 8 0.511869 5 0.511862 7 0.511843 7 0.511865 7 0.51187 7 0.511867 6 0.511883 5 0.51187 6 0.511852 6 0.511853 7 0.511859 8 = 0.710234 0.511861 mean 14 10 std dev of pop 8 4 2 std errors from mean 0.710240 0.511860 accepted value 164 Table C.ZZ. Results of replicate isotopic analyses. ConcencMlcions (ppIII) S8IIIple 143Nd/1~ % DIFF 147Sm/144Nd % DIFF Eps-Nd 87Sr/86Sr % DIFF Nd Sal Sr PCGM-1 0.511326 0.07'9996 -25.6 0.739653 112 14.83 2n.8 PCGN-1R 0.511363 0.007 0.080150 0.19 -24.9 0.739581 0.01 112.35 14.9 275.25 CH11 0.512269 0.100803 ·7.2 0.705822 19.66 .. 3.28 709.3 CH11R 0.512285 0.003 0.100433 0.37 ·6.9 0.705854 0.005 18.89 3.2 697 Table C.III. statistical data on analyses of USGS whole rock standards RGM-l, SCO-l, and W-2 • •••••• •••••••• •••••• RGH·l .••.••••••••••••••• SCO·l ••••••••• - •• - ••• -.-•••• • ••.••••••••• -.-•• - •• U·2 ------•••• -.- 25 I gma' Error Precision 21 1II'U' Error Precision 211gma Error Precision Accepted Hean Islgma mean N • X X Accepted Hean 1119111 mean II. X X Accepted Hean Is IglIIII mean N = X X Sc 4.7 4.63 0.52 0.25 17 '1.59 5.5 11.0 11.39 1.03 0.52 16 3.56 4.5 35.70 37.42 7.42 3.17 22 4.82 8.5 Cr 4.0 5.40 1.56 1.04 9 34.89 19.3 71.0 68.89 7.52 3.54 18 ·2.97 5.1 91.51 BO.92 24.04 11.03 19 -11.57 13.6 Co 2.3 1.92 0.31 0.15 17 '16.62 7.8 11.0 10.97 0.84 0.42 16 '0.29 3.8 43.15 41.56 4.71 2.01 22 -3.69 4.B HI 6.0 1.99 O.BO 0.40 16 '66.85 20.1 30.0 26.53 1.76 0.98 13 '11.58 3.7 70.40 65.62 10.03 4.10 24 -6.79 6.2 CU 11.0 11.01 0.93 0." 111 0.06 4.0 211.0 211.59 2.02 0.90 20 2.12 3.2 106.20 102.28 17.99 6.80 28 '3.69 6.6 Zn 36.0 35.73 2.95 1.35 19 '0.75 3.8 105.0 103.58 10.08 4.62 19 '1.35 4.5 79.60 76.011 9.65 3.n 27 ·4." 4.9 Ga 15.0 16.45 1.43 0.79 13 9.65 4.11 14.0 16.48 0.94 0.54 12 17.611 3.3 16.110 17.77 2.53 1.03 24 S.7B 5.11 Rb 115.0 150.55 7.B9 3.B3 17 30.91 2.5 115.0 112.16 7.34 3.06 23 '2.47 2.7 20.90 19.77 1.73 0.72 23 -5.40 3.6 Sr 100.0 107.73 5.79 2.59 20 7.73 2.4 170.0 166.54 7.73 3.46 20 ·2.04 2.1 192.00 193.31 14.27 5.82 24 0.68 3.0 25.0 22.81 1.33 0.66 16 '8.76 2.9 27.0 22.82 1.01 0.46 19 -15.49 2.0 23.00 20.64 1.58 0.66 23 -10.26 3.2 Zr 200.0 211.73 36.03 19.26 14 5.86 9.1 135.0 165.82 14.15 6.86 17 22.83 4.1 100.00 93.011 8.14 3.40 23 '6.92 3.6 ~ 10.11 1." 0.59 15 na 5.8 12.79 0.76 0.39 15 na 3.1 6.75 8.89 1.26 0.54 22 31.77 6.0 ~ 2.1 2.51 0.51 0.26 15 9.13 10.4 1.4 1.33 0.16 0.07 22 ·4.Bl 5.2 0.70 0.511 0.17 0.08 19 ·16.95 13.1 ~ 1.3 1.23 0.21 0.10 18 '5.38 8.2 0.4 2.52 0.35 0.16 20 529.38 L2 0.85 0.79 0.15 0.06 22 '6.53 B.2 ~ 9.55 0.54 0.25 19 na 2.6 7.8 7.54 0.23 0.10 20 -3.29 lA 1.01 0.85 0.09 0.04 22 -16.19 4.7 h BOO.O B02.63 41.U 19.03 19 0.33 2.4 590.0 564.71 19,98 9.42 lJ1 ·4.29 1.7 173.60 166.59 10.90 4.45 24 '4.04 2.7 ~ 23.0 23.47 1.49 0.66 19 2.03 2.9 29.0 28.60 1.60 0.73 19 -1.39 L6 10.36 10.09 0.92 0.37 25 -2.SB 3.7 ~ 46.0 47.02 2.89 1.33 19 -2.04 2.8 63.0 57.19 2.69 1.23 19 -9.22 2.2 23.37 22.15 2.33 O.Bl 33 -5.20 3.7 ~ 19.0 19.74 1.30 0.56 20 3.88 3.0 27.0 26.25 1.22 0.53 21 '2.78 2.0 13.36 12.60 1.07 0.38 32 ·5.69 3.0 ~ 4.3 4.09 0.31 0." 20 ·4.98 3.4 5.1 5.00 0.21 0.09 22 '2.03 1~ 3.31 3.17 0.27 0.09 33 '4.17 2.9 ~ 0.7 0.66 0.06 0.03 21 '6.39 4.1 1.2 1.13 0.05 0.02 24 '5.94 '1.6 1.12 1.08 0.07 0.03 32 -3.96 Z.4 ~ 4.17 0.34 0.15 22 na 3.5 4.2 4.80 0.21 0.11 14 14.17 2J 3.90 3.91 0.32 0.11 34 0.34 Z./I Th 0.62 0.10 0.04 22 na 6.8 0.11 0.71 0.06 0.03 21 ·11.31 3.6 0.66 0.62 0.07 0.03 32 -5." 4.0 ~ 0.76 0.09 0.04 22 n. 5.0 0.9 0.83 0.05 0.02 22 ·S.23 2.4 0.611 0.77 0.05 0.02 28 13.15 2.6 ~ 2.38 0.16 0.07 22 n. 2.9 2.5 2.41 0.11 0.05 22 '3.45 1~ 1.60 2.27 0.10 0.04 31 ".611 1.7 ~ 0.35 0.09 0.05 12 na 15.0 0.5 0.36 0.05 0.03 14 ·27.86 ~1 0.38 0.32 0.03 0.01 lB ·14.60 3.9 Th 2.5 2.56 0.08 0.03 21 2.57 1.4 2.2 2.31 0.011 0.04 23 5.12 1.5 2.14 2.08 0.14 0.05 34 '3.03 2.2 W 0.40 0.07 0.03 22 na 7.3 0.37 . 0.06 0.02 22 na 6A 0.33 0.31 0.02 0.01 27 ·5.51 2.5 Hf 6.0 6.26 0.31 0.13 21 4.2:> 2.1 4.3 4.69 0.18 0.08 19 9.16 1.8 2.60 2.67 0.13 0.05 33 2.Bl 1.7 h 1.0 1.20 0.21 0.09 21 19.86 7.7 0.9 1.07 0.19 0.09 17 18.37 L5 0.52 0.91 0.19 0.08 23 74.19 8.11 u 1.6 1.71 0.13 0.06 18 6.87 3.5 1 1.85 0.12 0.05 19 ne 2.9 0.26 0.50 0.15 0.07 11 91.43 14.6 ~ 21.0 22.78 O.Bl 0.37 19 B.48 1.6 26.0 30.46 2.78 1.19 22 8.78 3~ 7.66 7.60 0.40 0.14 34 ·0.B4 I.B t Th 15.0 14.74 0.61 0.27 21 '1.75 1.8 9.6 9.29 0.46 0.19 24 -3.23 2.0 2.41 2.26 0.19 0.07 33 ·6.31 2.9 O u 5.8 5.59 0.39 0.17 21 '3.59 3.1 2.9 2.9/1 0.17 0.011 21 2.74 2.5 0.49 0.51 0.04 0.02 21 3.98 3.4 VI 166 Table C.IV. comparison of Nd, sm, sr, and Rb concentration data obtained by isotope dilution and by ICP-MS techniques. Nd Sm Sr Rb Sample IO ICP-MS ID ICP-MS IO ICP-MS IO ICP-MS B42 31.07 35.28 5.21 5.36 529.5 541.4 111.4 120.0 B3al 29.83 27.98 4.96 4.63 463.1 451. 9 134.0 131.6 B3bl 26.63 27.58 4.40 4.30 565.8 623.5 107.1 128.2 B33 42.35 47.01 7.34 7.31 859.9 797.7 90.7 92.7 B62 22.16 20.01 3.40 2.94 287.5 257.9 189.7 B51 28.35 24.58 4.75 4.26 598.5 560.4 114.8 110.2 B22 16.70 14.06 2.99 2.71 154.2 155.2 108.0 82.1 CBll 23.34 24.50 4.37 4.52 851.6 860.5 29.7 30.1 CB23 18.56 17.41 2.85 2.72 749.1 656.6 73.6 55.3 CB3l 16.09 15.01 2.78 2.63 724.1 643.0 74.1 57.1 CB4l 16.80 14.89 2.90 2.73 1000.9 727.3 63.7 20.2 C43 17.72 16.24 3.18 2.91 438.8 400.7 127.6 116.6 C22 19.55 17.48 3.42 3.12 363.6 337.9 134.2 122.5 C12 13.57 11.82 2.05 1.80 73.8 60.4 151.2 125.6 C13 22.72 22.63 4.46 4.50 659.2 655.2 89.9 86.8 C31 32.18 27.25 4.33 3.83 224.9 193.3 162.0 138.6 CKl 24.43 19.94 3.97 3.36 936.0 721.0 52.1 6.8 011 25.88 25.13 4.14 4.08 779.7 763.8 62.0 60.5 031 20.00 19.98 3.64 3.65 450.1 491.8 102.0 110.2 PBBA-1 14.56 13.76 3.76 3.57 178.3 173.1 22.2 21.1 PCGN-1 112.01 115.11 14.83 15.62 271.8 265.2 143.8 142.2 PDCA-1 13.90 11.90 3.75 3.55 186.1 165.9 666.3 3.1 PJG-1 10.11 8.33 2.77 2.41 293.4 258.1 3.8 3.4 PLDA-1 14.65 9.51 4.03 2.59 211.5 136.7 2117.8 0.3 R31 15.46 15.70 2.54 2.48 543.7 50S.1 99.2 107.1 R32 11.40 11.32 1.90 1.81 40S.5 374.5 99.2 92.5 CH11 19.66 17.96 3.28 3.19 709.3 67S.0 50.6 48.0 Rla2 22.24 18.46 4.28 3.61 677.0 840.0 133.1 91.1 R1a4 23.06 22.03 4.90 4.64 795.9 832.2 27.9 29.4 R21 24.07 21.82 4.22 3.85 614.5 662.1 61.4 64.9 R2a7 5.74 5.34 1.12 1.26 699.3 654.8 31.9 29.3 R11 33.86 34.10 6.95 7.03 579.5 645.9 59.4 64.8 R42 19.03 17.08 3.36 3.16 363.6 353.1 133.0 126.S CHl 7.54 7.10 1.85 1.74 504.8 545.3 14.5 CH3l 19.33 16.12 3.29 2.S5 680.2 660.9 47.5 SF32 6.29 5.62 loll 1.01 525.5 454.9 66.2 58.2 SF21 17.29 15.64 3.19 2.92 628.4 553.5 75.3 66.0 SF33 11.48 9.13 2.08 1. 7S S03.7 390.5 56.8 22.7 SF34 12.18 10.98 2.20 2.04 372.1 350.6 66.0 61.S SF17 14.22 12.70 2.85 2.S8 824.5 749.4 24.2 22.3 Tll 20.19 18.78 4.77 4.59 642.9 620.9 36.9 22.7 T32 30.36 30.00 5.69 5.1S 201. 9 193.4 144.9 139.4 T21 30.25 28.90 5.62 5.43 492.9 530.0 117.0 125.6 T22 30.00 31.95 5.70 6.23 462.3 470.0 139.3 132.6 T43 9.87 8.61 2.S1 2.20 45.4 4S.4 246.0 247.S T2aS 31.44 29.14 5.78 5.42 266.2 262.1 127.2 125.7 Y2 23.17 23.02 5.01 5.15 493.6 502.6 46.1 47.2 Y3 7.41 7.14 1.56 1.50 874.6 11.4 11.4 10.5 Y5 23.S9 23.49 4.10 4.10 1354.2 1240.2 69.0 34.9 Y8 14.75 14.96 2.48 2.64 829.2 741. 3 40.6 34.9 Y9 15.87 14.57 3.04 2.95 903.7 90S.1 3S.0 35.2 8 I 7 A 50 • /' / 7~ .'5%/ 115% .. / / ~ ,/ •/ x&y /- 40 6~ 5~ O;/.:: e- /d / 30 o. -:r t¥" ~~ .•. ,~/ 0. ,/ ,..- 4~ /. -c - .~~~/ ./~ /' o 3-1 ~~. 20 J' /' :;:: ./- / .3 Samarium 2-1 .g, // i5 Neodymium 10 I ~./ CD 0. o o -.!!! 0t' o 1 2 3 4 5 6 7 8 10 20 30 40 50 .c> 1400 250lr------~------~7 ~ • c t15% o 1200 + 15% //' /' _,Ii"-" 1ii // .. 200 x=y C 1000 ./ -CD • o C o 150 800 - o 600 100 400 •• • Rubidium Strontium 50 -l • • .,,~/ 200 oIL a o 50 100 150 200 250 O· 200 400 600 800 1000 1200 Concentration by ICP-MS (ppm) .... 0'\ Figure C.1. Comparison of Nd, Sm, Sr, and Rb concentrations as determined by isotope dilution and iCI'-QMS techniques...... 168 APPENDIX D ANALYI'ICAL RESULTS AND NORMATIVE AND MODAL MINERAWGY The results of analyses for whole rock major element oxides (in weight percent) and CIPW normative mineralogy calculated from the whole rock data are listed for each sample in Table DJ. The results of analyses for trace element composition are contained in Table D.II and are listed in parts per million by weight. Table D.III lists the results of Sm-Nd and Rb-Sr isotopic analyses along with model ages and other related information. Table D.IV lists the modal mineralogy of each sample, as estimated by point counting techniques, and Table D.V assigns the appropriate lUGS nomenclature to each sample. Table 0.1. Results of whole rock analysis for major element~ and CIPW norms. BAGDAD OISIRICt OIAHOND JOE SHICK I ~"",'lo I UZI UU UZ us u~ U) 1S6 15.1 Ilbl .5W 142 M)1 1~2 161 I!lll 012 DIS 014 021 OU uSI OSZ ou O~I o~Z 0)1 I •·· .. ··I·.···a ...... •...... ·.. ·•. ·.•. ·.·· •.. ··· •.. ··· •.••..••• ··1 .•.. ··· •.. ·· .•.....•...... :...... •.•...••.. 1: 5102 115.8276.14 61.1159.11 65.2158.99 59.88 66.60 66.26 61.94 65.18 66.10 68.00 69.a5 161.9266.30 M.l0 66.00 65.70 M.50 70.70 71.00 n.50 15.60 13.60 11.30 1102 I 0.12 0.18 O.M 0.13 0.58 0.80 0.68 0.38 0.45 0.41 0.55 0.47 0.40 0.28 I 0.46 0.46 0.60 0.50 0.49 0.60 0.18 0.16 0.11 0.05 o.~ 0.05 AlZOJ 113.83 13.29 16." 16.95 15.82 16.59 16.13 14.90 15.60 ".92 15.50 15.40 15.40 14.98 116.3116.0016.50 15.50 15.80 16.40 14.50 15.80 14.70 13.70 13.10 12.10 F.20S I 0.40 0.\3 3.85 2.57 2.75 3.42 4.09 0.88 1.41 2.58 3.26 1.14 1.94 1.00 I 1.65 1.11 1.99 1.54 1.61 1.50 0.91 0.11 0.78 0.12 0.26 0.04 FeO 10.13 0.26 1.42 3.14 2 2.83 1.61 1.54 2.19 1.29 0.9 1.16 0.59 0.26 I 0.9 1.05 1.48 1.48 1.16 1.54 0.39 0.26 0.39 O.IS 0.3 0.13 "nO I 0.01 0.01 0.09 o. IS 0.09 0.15 O.!O 0.02 0.05 0.05 0.02 0.02 O.OS 0.02 I 0.04 0.04 0.06 0.06 0.0] 0.04 O.OS O.OS O.OS 0.01 -0.01 '0.01 MyO I 0.01 0.01 2.54 2.61 2.32 3.00 2.50 1.55 1.66 1.34 2.31 1.50 0.93 0.42 1 0.11 0.96 1.29 1.13 1.11 1.25 0.32 0.27 0.31 0.09 0.05 0.08 ceo 1 0.~9 0.56 4.85 5.55 4.25 5.45 5.38 1.91 5.31 2.70 1.82 1.75 0.49 1.55 I 3.02 2.94 3.56 3.10 2.58 3.23 1.50 1.66 1.50 0.21 0.26 -0.01 No20 I 1.'0 3.23 3.67 3.62 5.62 S.~8 5.41 3.38 1.80 3.17 3.14 1.31 4.00 2.67 I 4.58 4.50 4.26 5.92 4.65 4.12 4.24 4.95 4.27 3.~2 3.56 2.97 KZO I '.Z5 3.25 3.27 2.63 3.42 2.64 2.85 3.55 3.69 4.03 3.13 3.84 4.69 5.45 I 3.26 3.11 3.01 2.93 3.26 3.01 3.70 3.01 3.77 5. IS 5.61 5.17 PlOS 1 0.01 0.01 0.25 0.30 0.19 0.30 0.27 0.28 0.10 0.10 0.14 0.31 0.21 0.G6 I 0.13 0.30 0.25 0.37 0.38 0.15 0.12 0.04 0.14 0.16 0.24 '0.01 lOI I 1.22 0.81 1.01 1.10 1.03 1.28 1.27 1.88 0.80 0.9S 2.60 2.30 2.26 2.65 I 0.60 0.51 0.61 0.83 0.98 1.24 0.66 0.58 0.52 0.78 0.52 0.81 Bo I 0.03 0.10 0.1 0.09 0.1 0.11 0.1 0.08 0.09 0.09 0.11 0.10 0.11 0.11 I 0.13 0.12 0.10 0.10 0.12 0.13 0.12 0.06 0.10 0.04 0.01 0.01 ...... '1' -. -,. ----.... --.--. -.. -----.- --- -. ---... --...... -.. , -..... -.. -.... --.-...... ··1······ .•...... -...... -... , .. , .... -. ·--·······1 SUI! 191.7297.9899.54 98.n 99.42 99.04 98.99 96.93 99.51 99.35 99.86 98.06 98.91 99.30 199.8391.9891.8191.4691.85 91.71 91.31 98.5399.1899.5091.61 98.n I HZO- I 1.10 0.511 O.M 0.86 0.74 0.92 0.82 1.~ 0.53 0.11 2.2 1.15 I.M 0.89 I 0.50 0.31 0.44 0.59 0.81 1.12 0.42 0.39 0.38 0.50 0.41 0.60 I S 1 0.03 <.02 0.02 <.02 0.02 <.02 <.02 0.23 0.03 0.02 0.04 0.43 1.42 0.39 I c.02 c.02 0.02 c.02 0.05 c.02 0.03 c.02 <.02 c.02 <.02 c.02 I CI I <.01 0.01 0.04 0.02 0.04 0.03 0.02 <.02 0.02 0.03 0.01 0.OJ4 c.Ol 0.02 10.010 O.Oll 0.024 <.02 <.02 <.Ol <.Ol 0.020 0.034 <.02 0.020 c.02 I 10.091 0.011 0.077 0.084 0.068 0.013 O.OM O.09S 0.051 0.~3 0.084 0.019 0.061 0.013 10.062 0.055 0.085 0.093 0.115 0.115 0.055 0.060 0.052 0.015 0.019 0.019 I AtCNK 111.71 I.S5 0.88 0.90 0.91 0.90 0.90 1.16 0.95 1.0} 1.15 1.20 1.23 1.14 10.99 0.99 0.99 1.02 1.00 1.03 1.06 1.10 1.06 1.17 1.05 1.15 I ·······1··············································...... ,...... "...... q 2 150.}1 4S.68 15.35 12.38 17.49 tS.'l 15.00 21.08 19.93 26.58 22.20 21.60 25. \1 29.68 121.55 21.34 lS.81 24.37 20.16 20.31 28.5226.84 29.95 35.78 31.10 40.06 or 125.12 19.21 19.32 15.54 20.21 15.60 16.M 20.98 21.SI l3.82 l2.04 22.69 21.12 lZ.ll 119.21 IS.38 11.19 11.12 19.2111.85 21.8111.19 22.28 !0.32 33.51 30.55 ob 111.8521.35 S1.05 SO.6S 30.63 29.45 29.3628.6032.1526.8231.6528.0133.8522.59 IS8.16 38.08 S6.05 !J.ll 39.18 14.86 35.88 41.89 36.13 28.94 SO.12 25.13 an 12.37 2.71 17.91 22.23 16.8221.8521.66 1.6514.8012.14 8.11 6.26 0.67 7.30114.13 12.63 16.0S 12.96 10.32 15.~ 6.66 7.91 6.53 0.29 6.06 3.46 2.10 0.61 2.34 3.50 3.50 2.01 I 0.13 0.60 0.36 1.13 0.87 0.84 1.08 1.48 1.20 2.41 1.21 1.62 di 3.52 2.70 2.30 2.56 2.54 1.02 hr 0.02 0.12 4.69 8.24 5.11 1.59 5.05 5.32 5.14 3.34 5.15 4.18 2.32 1.05 1.92 2.39 3.41 3.55 2.81 3.19 0.80 0.61 0.77 0.30 0.41 0.34 ..t 0.1 0.19 3.02 3.n 3.99 4.96 3.39 1.28 2. tS 3.01 1.31 1.65 0.2 1.7 2.12 2.89 2.23 2.3S 2.11 0.83 0.47 0.86 0.11 0.38 0.06 (I 0.23 0.34 1.22 1.39 1.10 1.52 1.52 o.n 0.85 0.18 1.04 0.89 0.16 0.04 0.87 0.87 1.14 0.95 0.93 1." 0.34 0.30 0.32 0.09 0.08 0.09 hem 0.S3 1.77 1.15 0.26 2.31 1.81 1.00 0.48 0.25 0.34 0.311 0.19 tl ap I 0.02 0.02 0.58 0.70 0.44 0.70 0.63 0.65 0.23 0.23 0.32 0.86 0.63· 0.14 I 0.30 0.10 0.58 0.86 0.88 0.35 0.28 0.09 0.32 0.11 0.56 0.02 I ru 1 I I other I I I 01 3 I 81.3 90.2 65.1 58.6 68.3 58.5 61.2 16.1 13.9 11.2 15.9 78.3 86.1 114.5 I 19.6 11.8 n.l 14.9 78.6 n.o 86.3 86.5 88.4 95.0 94.1 95.1 I ••••••••=- ••••• =...... _ ...... : ••••••••••••• _ •••= ••••••••••• :: ••••:. 1 A/tNK •• h ..1 nos hr Index; ..,I ..ular rlt 10 of AI203/CCIO •••ZO • (20) 2 Abbr.vlatlon.: q. quartz; or • orthoct ••• ; .b •• lblte; an. anorthlt.; C • conrO.n; dl • dlopllde hy • hypenthene; lit • _anetha; It • Hacnle.; hna • hematlt.; tl • tltanlt.; Ip. apetlte ..... rut· rut lie; ne • nepheline; ot • olivine 0- \0 J 01 • Ihornton ono.l luttle (196U) dllferentlotlon Ind.. ; 0... 01 nor ... ,lve quoru. koper ••Iblt. Ir"d nepllellne Table D.I. continued. lei INGI COPPER BASI. DiStRICT I COPPER CREE&: DISTRICT SAFfDilO DISTRICT I Sanple I CKI I call Ca23 CUI cau I C13 CI2 CZZ ell CU CU CU C45 I IF15 SFI6 SF17 SF21 SFa $F32 SF33 SF34 SF" SFO I CHI CH2 ...... ,..... :I ~ .... =••••• =:a •••••& ••••• , ••••••••••••••••••••••••••••••••••••••• a········I··········.······················· ...... :: I·· ... ···.· .. . 5102 166.90 152.9068.2066.4065.30 159.1019.4068.6073.1061.1062.2062.1061.40 153.8059.30 58.60 63.20 60.50 61.40 65.869.1052.10 50.90 148.58 52.20 1102 0.41 0.55 0.30 0.35 0.31 I 0.a8 0.12 0.40 0.20 0.39 0.70 0.58 O.M 10.111 0.79 0.79 O.U O.U 0.45 0.5 0.29 0.71 0.90 I 1.16 1.10 AI 20) 6.50 5.5015.6015.1015.90 p6.20 11.30 ".50 13.40 15.20 15.80 16.10 16.10 p8.10 17.00 17.9016.5016.40 H.80 15.315.5019.50 111.50 pa.06 11.20 Fe203 2.01 2.57 1.56 1.10 1.65 I 2.75 0.28 1.50 0.65 0.56 2.38 1.63 1.60 I 4.11 2.18 3.81 1.33 1.98 1.112 1.84 0.67 3.55 1.34 I 5.63 6.12 f.O 1.12 5.18 0.9 1.42 1.68 I 2.33 0.39 1.17 0.26 1.11 2.59 3.24 3.24 1 3.95 3.24 2.01 2.2 1.94 2.07 1.91 0.39 3.11 1.04 I 4.18 3.89 HnO 0.04 0." O.OJ 0.03 0.03 I o.oa 0.04 0.03 0.02 0.02 0.04 0.05 0.05 I 0.14 0.05 0.11 0.05 0.11 0.04 O.OJ 0.04 0.09 0.16 I 0.15 0.15 "gO 1.01 6.82 0.87 1.28 1.35 I 2.M 0.39 1.36 0.49 1.48 2.69 3.01 3.411 I 3.M 3.55 3.211 2.09 2.30 1.79 2.01 0.53 2.89 3.10 I 5.65 5.10 ceO 3.40 9.25 2.71 2.20 2.65 I 4.74 0.09 2.54 0.98 2.97 2.63 2.47 4.32 I 7.91 4.9a 6.22 4.211 3.98 2.44 2.56 0.82 7.114 7.14 I 8.114 8.70 N.ZO 5.12 2.96 4.02 3.53 3.79 I 4.46 0.51 3.73 3.00 3.73 4.18 3.89 3.n I 3.02 3.29 4.49 4.12 4.13 3.69 3.82 4.48 4.58 4.31 I 2.65 3.00 1:20 2.77 1.21 3.18 3.211 2.70 I 3.02 4.39 3.65 5.55 3.98 2.76 2.30 2.36 I 1.42 1.79 I.n 2.31 3.21 3.41 2.93 4.32 1.27 2.97 I 1.011 0.80 P205 0.21 0.20 0.15 0.17 0.24 I 0.45 0.13 0.35 0.08 0.18 0.44 0.19 o.n I 0.40 0.58 0.26 0.14 0.34 0.16 0.13 0.20 0.55 0.21 I 0.13 0.06 LOI 0.59 1.20 1.42 3.91 3.23 1'.23 2.U 1.03 0.63 1.117 2.15 2.92 1.75 10.65 1.94 1.04 1.29 2.89 0.911 2.17 1.63 0.99 3.23 13.111 3.70 Sa 0.12 0.03 0.12 0.12 0.1 I 0.1 0.1 0.06 0.06 0.06 0.06 0.05 0.06 I 0.04 0.03 0.09 0.08 0.09 0.11 0.01 0.1 0.05 0.08 I 0.03 •• "" ·1· •••• '1-"'" .•.•••••.••.•.••• ·1·················· •••••. ························1··················· ••• , •.••. , •..•.••••••••.• , •••.•••••.•..•. ,. -1-""" -••. -- SUII pOO.2 198.51 99.0698.8998.99 198.5899.4698.9299.0299.3198.6298.5599.05 197.99 98.7Z 100.3298.8898.5099.1699.1998.6797.89 100.6 199.32102.02 H20. I 0.211 I 1.09 1.01 2.61 2-'6 I 0.94 2.09 0.93 0.1 2.19 1.66 2.36 2.59 I 0.83 1.11 0.91 2.2 1.11 0.17 1.5 1.36 1.11 2.01 I 2.16 0.1 5 I <.02 I 0.19 0." 0.6 0.13 I 0.02 0.04 0.06 0.11 0.82 0.02 0.02 0.64 I 0.02 0.01 0.02 0.56 0.02 O.OJ 0.08 0.02 0.05 O.OS I 0.02 CI I I I I I <.01 <.02 F I I I I I 0.02 0.0 A/CHK 11 0.94 10.61 1.04 1.13 I." 10.84 1.96 0.99 1.05 0.96 1.08 1.20 0.9110.111 1.04 0.81 0.96 0.94 1.04 1.08 1.15 0.84 0.79 10.84 0.80 8•••• :_1 : •••• ::: I= •••• = ••••• : •••••=1:: •••• : I•••• ;. •••••••••••• -= •••••: •••••= •••••••••••••••••• 111: •••••••••• [\ ••••••••• a •• ==~= •• =•• II: ••2 •••••2 ••lf ••••• II: ••• II:==.c •• = I=.=.====-=::1::1= q 2 118.67 I 2.6925.9626.66 25.38 110.2059.06 26.31 32.4022.34 18.14 19.69 15.54 I 9.36 17.65 9.61 19.06 12.8724.7023.5625.12 0.56 I 3.31 7.88 or 116.37 I 7.15 18.19 19.38 15.96 117.8525.9421.5732.8023.5216.31 11.5911.95 18.3910.58 10.1614.01 18.9720.1517.3225.53 7.51 17.55 16.38 4.73 ab 143.32 125.05 34.02 29.117 32.07 137.74 4.3231.5625.3931.5635.37 32.9231.48 125.5527.114 37.99 34.86 34.95 31.22 32.]2 37.91 38.76 ]2.76 122.42 25.39 an 13.116 125.U 12.46 9.8011.58 115.27 10.31 4.3412.9810.1711.01 19.28 31.64 20.92 23.61 16.4016.73 11.06 11.85 2.1628.90 22.09 134.20 31.11 C I 0.98 2.15 2.50 I 5.86 0.63 0.117 2.21 3.18 0.36 1.98 1.15 0.99 1.5 2.44 I di 1.27 115.41 I 4.18 0.'6 3.99 4.32 0.63 5.08 9.00 1 6.93 9.12 hy 1.92 p6.31 2.17 4.31 4.53 I 5.32 1.33 3.69 1.22 4.54 11.41 11.28 12.35 9.94 11.78 6.17 7.20 6.52 6.09 6.411 1.32 6.25 112.21 9.00 .t 2.55 I 3.71 2.13 1.59 2.39 I 3.99 0.41 2.11 0.32 0.81 3.4S 2.36 2.32 5.96 3.16 4.55 1.93 2.87 2.64 2.67 0.5S 5.15 1.27 I 8.16 8.87 II 0.78 I 1.04 0.57 0.66 0.70 I 1.67 0.23 0.16 0.38 0.74 1.33 1.10 1.22 1.54 1.50 1.50 1.20 1.20 0.85 0.95 0.55 1.71 1.71 I 2.20 2.09 hem 0.25 I 0.09 I 0.41 0.67 0.29 6.41 I tl I I I ep 0.49 I 0.46 0.35 0.39 0.56 I 1.04 0.30 0.81 0.19 0.42 1.02 0.44 0.76 0.93 1.34 0.60 1.71 0.19 0.31 0.3 0.46 1.27 0.63 I 0.30 0.14 ru I I 3.53(01)1 other I I 2.29(ne) I 013 78.4 134.9 78.8 75.9 73.4 165.8 89.3 19.4 90.6 71.4 69.8 66.2 61.0 43.3 56.1 57.8 67.9 66.8 ;6.1 73.2 BII.6 46.8 50.3 132.1 38.0 ~1I:=.===.= •••• =.= ••:.:.==1I:.=.:::= ••1I:.= ••••• =.= ••••= ••••• 2 ••• ::1.== ••••: ...... = ...... _ ...... = ••••• ::1.== ••:&-= •••• : •••••••••:.:::1 ••=.====2.=:&:.:&=.=:::1=== ••==: ...... a Table D.I. continued. RAY AND tHlISTIIAS DISTRltTS SlIIIl'le I CH.l III RI3 114 CHll CH12 CHI2A CH121 CH12C CHU CH14 .1., .,12 .'al .,a4 R21 R22 12.4 I2S 12.7 CH31 CH32 131 132 133 134 ••:.aa: I :.:•• =...... =: ••••••: ••••••••••11: ••••••••••••••••••••••••= •••••• 1: ...... : •••••= ••••••••••• =••••• = •••••••••••• == ••• === ••••::.a ••• = Si02 156.11 511.00 57.30 60.90 66.11065.70 64.90 61.162.11953.36 61.9 67.6067.4059.50511.90 611.90 78.150.2371.11175.1064.110 66.75 71.110 n.30 71.50 77.7 Ti02 I 0.95 1.00 1.10 1.10 0.60 0.57 0.60 0.71 0.73 1.32 0.53 0.50 0.45 0.60 0.70 0.40 0.06 1.13 0.23 0.12 0.59 0.35 0.31 0.24 0.32 0.02 AI203 I 17.2 16.30 15.20 15.60 15.60 15.70 15.90 16 16.11 16.27 16.95 15.70 15.60 17.60 111.60 11.20 12.8 15." 15.01 16.90 15.60 15.7 14.90 14.10 15.10 12.5 fe203 I 4.1 3.82 4.04 3.51 2.70 2.71 4.60 4.23 4.55 8.111 3.02 2.30 1.116 3.03 3.92 2.69 0.311 7.97 1.05 0.76 2.60 1.7 1.14 1.02 1.28 0.4 FeO I 2.11 3.82 4.34 5.111 1.42 1.611 1.114 1.42 1.55 2.65 2.2 1.42 0.77 0.39 1.42 1.85 1.3 0.18 0.91 "nO I 0.1 0.13 0.14 0.14 0.06 0.06 0.06 0.01 0.07 0.11 0.111 0.06 0.06 0.12 0.11 0.11 0.02 0.12 0.06 0.03 0.0'; 0 0.05 0.04 0.04 0.01 "gO I 2.4 3.40 4.00 4.20 2.20 2.30 2.40 2.3 2.33 4.69 2.U 1.10 1.60 2.10 1.70 1.30 0.03 11.43 0.511 0.35 2.10 2.35 0.94 0.63 0.81 0.04 cao I 6.6 1.00 7.20 1.110 4.40 4.50 4.50 3.92 4.16 5.6 3.95 4.00 4.00 7.20 11.10 5.20 1.3 1.39 2." 3.110 4.10 3.55 2.50 2.10 2.10 0.4 Maze I 3.11 2.90 2.10 2.110 3.10 3.90 3.90 4.31 4.011 3.47 4.34 3.50 3.50 3.40 3.50 3.60 3 3.64 4.15 4.50 3.90 4.05 3.60 3.50 3.80 2.9 (20 I 2 2.40 2.30 2.20 2.20 2.30 2.30 2.22 2.22 1.84 2.31 2.70 2.110 2.00 1.60 2.20 5.4 1.117 2.97 1.70 2.30 2.15 3~]0 3.90 3.70 6 P205 0.4 0.07 0.05 0.07 0.06 0.07 0.05 0.23 0.15 0.16 0.21 0.05 0.04 0.06 0.011 0.05 0.02 0.211 0.06 0.55 0.04 0.24 0.04 0.05 0.0t, 0.02 lOI 0.19 0.20 0.10 0.50 2.50 1.50 1.50 1.99 2.03 4.19 1.63 0.60 0.50 0.110 0.]0 0.40 0.2 3.2 0.57 0.40 1.110 0.73 0.40 0.40 0.40 0.2 Sa I 0.07 0.07 0.06 0.06 0.08 ...... ·1·············.····.··.·.·...... ·.·.·.·. -.--. -- .. -. ----.... --- -. ------. -. ------. -- --. -.---.--.. -. --... -.... --. ---- -.-.. -... -. -.... -. -. -- ... -. -- SUM 197.]4 99.04 98.47 104.0 102.24 101.0 100.71 97.15 99.45 99.25 99.32 100.13 99.]699.06 99.77 103.47 101.] 99.7699.78 104.6 99.]0 99.42 100.28 99.06 100.6 100.2 H20+ 10.97 <.05 <.05 <.05 0.30 0.20 0.20 1.74 1.73 3.11 1.63 <.05 <.05 c.OS 0.05 c.05 <0.05 2.64 O.H c.05 0.2 1.12 <.05 <.05 <.05 <.05 s I c.02 0.03 0.02 0.02 0.05 CI I .02 <.02 <.02 0.02 0.02 0.02 c.02 0.02 0.02 0.03 0.02 c.02 c.02 <.02 <0.02 0.04 0.01 c.02 0.04 <.02 0.0] <.02 <.02 F I 0.1 0.1 0.1 0.04 0.04 0.04 0.032 0.041 0.065 0.03 0.03 0.03 0.04 0.05 0.03 0.05 0.05 0.02 0.042 0.048 0.03 0.04 0.02 MCNl 11 0.114 0.111 0.16 0.74 0.95 0.92 0.93 0.96 0.91 0.91 1.00 0.98 0.97 0.114 0.114 0.97 0.91 0.72 1.04 1.05 0.95 1.02 1.06 1.02 1.00 1.04 .:. ••• _c 1_ • .I: •• ==.:; •• ;5.~ •• ==&= •• 01.1::;_ s. •• zz.a •••• c •••• ~ ...... OI:II •••••••••••••••••••••••••••••••••••••••••• :a0l.= •• ~=.= •• =•• "' •• ==&.1: •• :::;.z •• =••••• z.:; •• =: •• == .=:".:=,,': •• : •• :.&2 q 2 111.6913.1012.9\ 14.30 24.75 22.05 20.96 16.39 111.111 16.]4 26.0225.39 14.711 14.77 26.116 31.311 30.25 35.3021.9024.09 31.\231.59211.211 31.0\ or 1".82 14.111 13.59 13.00 13.00 13.59 13.59 13.12 13.12 13.65 15.96 16.55 11.IIZ 9.46 13.0031.91 11.05 17.55 10.05 13.59 12.7 19.50 23.05 21.8735.46 Db 132.15 24.54 22.85 23.69 31.31 33.00 33.00 36.47 34.52 36.n 29.62 29.62 211.77 29.62 30.46 25.39 30.11 35.12 311.08 33.00 34.27 30.46 29.62 32.15 24.54 an 23.97 24.37 22.56 23.50 19.'6 111.54 19.09 17.76 19.25 17.11 19.16111.5926.116 30.32 24.28 5.5120.2711.71 15.2618.2715.57 12.14 10.09 13.13 1.85 0.8 0.16 0.68 2.07 1.01 0.96 0.42 0.0] 0.56 di 4.53 7.91 10.26 11.92 1.54 2.59 0.82 0.28 0.79 6.78 7.27 0.93 8.64 1.41 hy 4.23 7.14 11.13 9.75 4.77 4.54 5.60 5.73 5.80 6.39 4.10 4.29 3.59 0.116 2.111 11.41 l.n 0.87 4.511 7.27 1.]7 1.84 2.18 0.1 lit 5.94 5.54 5.86 5.09 3.03 3.93 4.311 3.32 2.7 4.39 5.62 3.711 1.52 1.01 3.03 2.41 1.65 1.48 1.86 \I 1.11 1.90 2.09 2.09 1.14 1.08 0.13 0.15 0.15 1.01 0.95 0.115 1.14 1.33 0.76 0.04 0.26 0.44 0.23 1.12 0.67 0.59 0.46 0.61 0.02 h ... 0.61 4.60 4.23 0.01 0.05 0.09 0.38 7.97 0.01 0.51 0.4 tl 1.31 0.13 0.09 2.44 op 0.91 0.16 0.12 0.16 0.14 0.16 0.12 0.53 0.15 0.49 0.12 0.09 0.14 0.19 0.12 0.05 0.65 0.14 1.27 0.09 0.56 0.09 0.12 0.09 0.05 ru 0.511 0.53 0.01 other 6 (01) DI 3 55.1 51.8 49.4 51.0 69.1 611.6 67.6 66.0 66.4 0.0 66.7 71.6 71.6 55.4 53.9 70.3 94.7 '1.9 82.9 83.4 68.5 71.1 81.1 114.1 82.3 97.0 .&=~===.=£.=c== ••=.:I& •• =••••••• ==I: ••••• =•••••• :;a ••••••••••= ••• =... .:;& ...... :1 ••••••• :::1 •••••••••••••••••••••••• £•••• c. •••••• r ••••••••••:: ...... =.a=.==.==.===.=.======..... '-J..... Table D.l:. continued. 1 IQIISIIlNE DISllICI PIECAHSIIAII 100:5 5...,1. I 041 042 151 1 111 112 113 121 122 123 124 125 l2e2 l2O} l2O} U2 143 144 IPOtAi PlDAI PLDA2 PLDA] "Gl2 PIGII 'IBAI PJC·I PCA'I PCA·2 ptG/HI •••••• ·1· ••••••••••••••••• 1••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• a •••••••••••••••••••••••• •••• ·1 ••••• •••••••••••• •••••• •••••• ••••• ••••• ••••••••••••••••••••••••••• 5102 164.22 6II.5S 66.99 153.20 55.10 53.9 66.60 64.SO 63.10 61.20 62.90 12.40 n.10 11.50 71.10 7S.10 7S.9O 15D.SD 41.00 411.45 45.24 4P.00 41.2 52.1 51.7 411.5 46.9 66.11 1102 10.49 0.34 0.62 I 1.30 0.10 1 0.66 0.10 0.61 0.115 0.115 0.17 0.311 0.39 0.17 0.06 0.06 I 1.20 1.119 1.113 1.l1li 2.01 2.711 1.1 0.9 1.25 1.33 0.41 AI20S \15.4015.5015.41 \111.50 16.20 15 15.10 15.4015.60 16.20 16.10 15.10 14.10 14.50 14.60 13.30 13.20 \15.40 13.59 13.9113.92 17.10 12.1 14.5 14.9 n.1I 15.2 IS.2 f.203 1 2.31 1.71 3.211 111.54 5.1S 4 3.13 2.63 3.04 5.91 6.35 2.12 2.90 0.97 0.34 0.62 0.63 I 4.10 5.7S 4.49 5.111 2.119 4.n 2.19 3.05 1.44 1.4 2.S4 f BAGDAD DISTRICT DIAIIOHD JOE STDCI( B21 B22 B32 B33 834 B3S &36 n.l a3bl B3b2 a4i! &51 BSi! B61 011 Dli! 014 022 031 .-. &."' ...... ~a ...... •••••••••••••••••••••••••••••••••••••• 11 ...... Cl ...... ;a.= ...... ~ ••• eo. Sc 3.20 1.99 11.34 11.41 8.95 12.60 10.47 5.U 5.69 5.12 10.37 4.99 3.46 i!.66 I 3.62 4.12 3.94 2.'1 2.54 Cr 4.09 0.00 11.27 10.71 8.45 8.63 4.90 6.01S 4.83 7.02 28.59 0.78 5.00 8.74 I 7.54 5.05 3.71 4.68 4.56 Co 0.53 0.07 14.62 15.42 14.53 17.24 14.72 8.13 11.99 7.59 10.97 7.94 27.55 3.83 I 5.28 5.69 6.55 4.13 1.40 Ni 2.60 0.13 11.69 6.111 9.11 13.55 6.50 4.73 5.07 4.42 12.55 6.51 7.10 1.411 I 3.25 3.23 3.43 3.88 0.70 Cu 2.02 9.89 41.07 40.21 95.13 46.88 43.80948.75 111.10 148.63 36.81 2071.62452.9988.411 I 2.28 10.05 89.88 19.84 7.88 20 7.82 10.37 88.29 106.05 90.43 80.55 95.14 29.69 34.011 30.60 45.72 28.54 26.411 15.95 I 51.49 52.98 70.18 31.40 217.74 GB 15.28 20.67 22.38 19.96 27.92 22.30 19.69 23.38 20.45 22.06 19.58 21.69 19.41 I 21.75 23.54 21.47 20.93 20.05 Rb J144.63 82.10110.04 92.70115.31 98.65103.70131.64128.16138.99 120.02 110.15 140.41 189.69 I 62.13 67.67 46.91 26.76109.45 Sr I 73.0 155.2 815.5 797.7 655.6 969.0 868.1 451.9 623.5 481.5 541.4 560.4 591.1 257.9 I 807.0 499.5 668.6 634.3 49B.5 I 11.90 19.01 24.15 17.21 28.45 23.75 17.70 14.32 16.27 17.91 12.93 6.17 6.49 I 9.15 9.93 12.61 10.37 12.94 Zr 154.95 56.78183.91 184.57189.90202.95 \88.80 1511.85 147.39 144.40 176.11 126.97141.36 nl.15 J161.63 186.09176.21 191.63 130.88 Nb I 5.24 12.54 11.23 12.79 10.61 13.25 12.51 12.96 12.91 12.28 8.76 6.57 I 6.72 8.62 7.90 11.25 Ho I 0.02 0.80 0.86 1.45 0.55 2.38 3.00 0.77 0.93 0.32 39.89 3.58 7.44 I 0.51 2.52 0.(3 0.74 0.14 Sb I 0.04 0.17 0.18 0.04 0.05 0.10 0.05 O. UI 0.04 0.23 0.211 0.611 6.15 I 0.00 0.04 0.01 0.08 0.12 Cs I 0.40 1.86 4.30 2.52 2.81 i!.411 2.96 4.36 1.91 3.00 5.53 1.113 1.59 2.56 I 0.39 0.54 0.83 0.90 0.60 a. 316.3 1161.1 1030.3 973.3 11117.0 1116.4 1030.9 991.6 9711.3 1025.5 1177.7 1222.4 1129.3 980.11 11253.1 1240.91063.0 1242.5 1266.1 Hf 3.00 2.51 5.48 5.10 5.38 5.43 5.08 4.96 4.77 4.62 7.96 3.92 4.27 3.77 4.73 5.31 5.01 5.31 3.87 Ta 1.96 1.29 1.15 1.28 1.24 0.77 1.00 1.64 1.19 1.62 1.53 1.03 0.59 0.59 0.42 0.53 0.58 0.45 0.91 \I 2.01 1.27 1.42 1.73 0.44 0.72 10.55 0.45 0.78 2.23 24.01 31.55 12.32 0.18 0.48 1.08 8.19 0.17 Pb 3.12 10.87 19.84 17.80 22.00 13.90 18.24 10.07 13.03 10.86 2i!.98 9.15 8.13 5.15 13.31 10.44 9.85 5.20 29.33 Th 6.95 10.18 11.12 10.04 12.01 10.65 9.42 15.69 13.U 17.14 10.35 9.22 4.97 5.31 4.44 4.71 4.40 3.92 7.60 U 3.12 1.47 3;06 1.79 3.24 1.47 1.97 4.8i! 2.60 3.35 1.84 i!.62 2.79 5.26 1.09 1.08 0.92 1.79 1.31 La 5.36 18.87 43.89 49.71 35.15 45.12 42.01 34.20 40.75 31.29 42.01S 28.23 30.51 23.76 24.80 31.52 29.56 26.67 21.71 Ce 11.39 36.71 88.92 99.58 72.19101.97 117.88 t9.14 74.91 63.59 82.17 57.48 59.31 45.92 51.20 62.22 63.91 66.47 42.69 Nd 4.89 1'.06 40.99 41.0t 31.08 45.22 38.91 27.98 27.58 25.69 35.28 24.58 24.07 20.01 22.19 27.18 28.38 31.86 17.70 Sm 1.06 2.71 6.27 7.31 5.38 8.19 6.71 4.63 4.30 4.22 5.37 4.26 3.62 2.93 3.65 4.46 4.69 5.18 3.28 Eu 0.07 0.60 1.48 1. 73 1.33 1.61 1.50 1.11 1.04 1.11 1.32 1.16 0.86 0.79 0.99 1.17 1.22 1.26 0.76 Gd 0.94 2.53 5.30 6.50 4.92 7.14 6.00 4.31 3.92 3.94 4.84 3.75 2.79 2.23 2.96 3.57 4.14 4.04 3.04 Tb 0.14 0.36 0.75 0.91 0.62 0.94 0.79 0.61 0.44 0.54 0.72 0.49 0.26 0.36 0.33 0.39 0.48 0.46 0.40 Ho 0.33 0.39 0.74 0.94 0.63 0.99 0.B3 0.60 0.41 0.58 0.70 0.47 0.23 0.30 0.31 0.36 0.48 0.40 0.41 Er 0.63 1.30 2.01 2.47 1.88 2.55 2.39 2.01 1.49 1.84 1.72 1.50 0.63 0.63 0.86 1.04 1.31 1.09 1.19 Tm 0.35 0.40 0.42 0.35 0.07 0.32 0.11 0.15 I 0.12 0.15 0.19 0.15 0.17 Yb 0.70 1.43 1.80 2.22 1.96 2.43 2.26 2.21 1.61 2.07 1.72 1.55 0.63 0.56 I 0.61 0.93 1.21 0.97 1.22 Lu 0.06 0.21 0.33 0.40 0.30 0.40 0.33 0.34 0.28 0.30 0.31 0.22 0.11 0.13 I 0.13 0.15 0.19 0.14 0.19 Eu/Eu· 0.21 0.69 0.77 0.75 0.78 0.11 0.71 0.75 0.76 0.82 0.78 0.117 0.80 0.91 I 0.89 0.87 0.81 0.61 0.72 .... (laIYb)NI S.2 6.9 16.5 15.1 12.1 12.5 12.5 10.5 17.1 10.2 16.5 12.3 32.7 26.7 I 20.7 22.9 16.5 16.5 12.0 ...... z::======:=====a=a==:zc=====:a======;c==:.:.=.::::===.=.:c.:: •• a•••••• =••• c •• :::;.=a.:.==3::;===:===.=:;:==c::=z=== ... :c====.:;:=:o:==_=:====z==== W Table 0.11. continued. I COPPER BASIN DISTRICT Ic. KINGI COPPER CREEK DISTRICT I 032 033 042 051 CBl1 CB23 CBlt CB'l I al I C12 ell a2 01 C43 C44 C45 SF15 5F16 ==:~==== :;;&&&:===I:&&===::'&.&:::=:::=a.*z: I =•• .z.=:;:=a.::.===z:~a.===I::.aa== I == ••• == 1·······I1:· ••• ··&= ••• ::::===.a======.====.: •• :;::;:;:a •••== I:a:=a===aa::== 5c 2.31 2.36 2.21 0.53 I 29.21 20.04 4.67 19.96 I 1.82 I 1.00 1.111 4.65 1.12 6.91 10.01 11.69 I 22.50 14.74 Cr 4.00 1.22 0." 01 116.03 1.15 11.20 1.111 I 1.21 I 2.113 61.07 10.10 2.17 31.31 52.90 69.;4 140.91 99.17 Co 1.10 1.61 0.50 0.20 I 43.34 4.71 1.69 5.59 I 2.11 I 0.31 15.63 1.02 1.86 12.11 19.61 18.96 I 25.61 16.50 Nt 0.82 0.89 0.29 0.21 I 90.17 5.64 1.31 5.44 I 2.16 I 1.20 33.20 9.10 4.97 26.15 29.39 39.11 I 20.61 31.19 Cu 0.61 1.10 4.54 28.63 100.25 15.78705.16164.44 I 1.98 I 5.29 45.88 13.351331.2 7.87102.80 51.00 134.38582.79 Zn 24.67 28.58 9.42 10.01 87.54 27.21 23.05 18.01 I 13.110 I 511.55 50.111 21.60 11.13 40.60 53.40 36.10 81.72 44.04 Go 24.79 24.14 23.40 20.55 17.90 16.84 16.18 17.01 120.25 I 9.64 21.87 17.81 12.94 19.86 20.34 20.03 24.44 23.24 Rb 109.80100.04180.00181.63 30.01 55.26 57.13 20.24 I 6.83 125.64 86.110122.45138.63116.64 101.13 105.14 54.17 62.20 5r 506.7 485.6 166.2 117.8 860.5 656.6 643.0 727.3 I 721.0 60.3 655.2 331.9 193.3 400.7 472.4 554.5 679.4 669.0 11.50 11.06 11.65 17.51 13.05 6.21 7.39 11.25 I 11.04 5.81 15.27 11.58 8.87 8.22 8.95 9.59 15.13 10.33 Zr 99.08118.75 20.48 12.14 85.92124.79 89.21 103.14 Jl77.10 79.98171.511 118.96 79.29120.78110.69 97.99 23.95 29.97 Nb 11.53 10.02 20.90 31.32 4.14 7.58 6.49 6.79 I 8.47 5.94 8.59 1.33 5.25 5.31 4.37 4.46 3.46 4.39 "0 0.09 0.70 0.15 2.70 0.68 0.71 6.67 0.59 I 0.211 0.15 1.55 0.94 83.03 1.11 1.22 1.37 0.89 6.42 Sb 0.04 0.34 0.46 0.53 0.10 1.65 0.28 0.111 I 0.02 0.55 0." 0.06 0.09 0.33 0.50 0.18 0.03 0.05 Cs 1.41 0.50 3.111 1.10 0.76 2.119 3.27 4.59 I 0.45 11.119 6.23 6.51 6.12 15.31 9.71 9.311 2.22 1.78 Be 107.2 1141.0 393.5 158.3 319.7 1179.4 1168.3 933.6 !t085.5 940.2 947.9 627.9 595.1 634.3 472.7 534.9 245.8 175.8 Hf 3.21 3.U 1.67 2.39 2.33 3.41 2.69 ].01 I 4.69 2.89 5.04 4.311 3.64 3.80 3.26 2.97 0.85 1.14 T8 1.21 0.69 3.03 5.23 0.33 0.65 0.511 0.59 I 0.46 0.63 0.66 1.04 1.36 0.50 D." 0.42 0.27 0.33 \I 0.29 0.10 1.30 2.95 1.29 21.99 11.59 3.00 I 0.20 0.94 1.23 1.34 4.47 11.54 1.85 4.611 0.35 1.21 Pb 17.78 21.87 23.31 18.48 4.70 9.76 1.08 2.95 2.16 31.15 11.86 9.44 15.45 11.64 9.08 6.51 2.21 4.19 Th 5.37 8.35 4.07 4.23 2.46 4.01 2.59 2.34 3.90 10.118 11.112 22.10 29.37 1.56 5.80 6.13 1.24 2.97 U 5.84 1.30 3.65 4.04 1.21 1.56 1.65 1.04 0.36 2.54 2.56 6.94 10.97 2.38 1.63 2.011 0.35 0.64 La I 10.39 20.33 1.71 4.18 I 20.71 25.04 16.82 11.40 I 21.13 I 11.55 20.64 20.12 46.44 16.81 15.14 14.22 I 8.05 12.84 Ce 20.56 ".28 16.11 7.72 I 46.411 45.26 33.09 29.91 44.30 31.74 46.16 43.111 87.08 35.52 32.17 30.29 18.27 28.55 Nd 8.97 17.94 6.10 3.64 I 24.49 17.41 15.01 14.89 19.94 11.82 22.63 17.411 27.25 16.24 14.38 13.B4 10.56 14.50 511 1.87 3.35 1.40 1.19 I 4.52 2.72 2.63 2.13 3.36 1.110 4.50 3.1l 3.113 2.91 2.63 2.67 2.57 2.94 Eu 0.61 0.71 0.35 0.25 I 1.41 0.79 0.83 0.81 0.96 0.44 1.22 0.68 0.62 0.82 0.78 0.111 0.98 0.94 Cd 1.89 3.05 1.61 1.64 I 4.13 2.23 2.30 2.38 2.15 1.57 4.24 2.91 3.11 2.65 2.40 2.54 2.95 2.68 Tb 0.28 0.40 0.32 0.40 I 0.51 0.26 0.28 0.30 0.32 0.20 0.55 0.311 0.34 0.33 0.30 0.33 0.44 0.35 Ho 0.38 0.41 0.39 0.56 I 0.50 0.25 0.29 0.32 0.28 0.23 0.57 0.43 0.33 0.32 0.33 0.35 0.56 0.37 Er 1.14 1.09 1.20 1.70 1.35 0.67 0.80 0.92 0.18 0.611 1.55 1.31 1.02 0.94 0.91 1.01 1.54 1.05 1111 0.18 0.19 0.18 0.10 0.12 0.14 0.11 0.11 0.23 0.20 0.16 0.11 0.13 O.IS 0.22 0.14 lb 1.28 1.13 1.54 2.22 1.17 0.70 0.85 0.98 0.73 0.83 1.53 1.41 1.21 0.92 0.91 0.92 1.46 0.98 Lu 0.20 0.18 0.22 0.30 0.17 0.12 0.14 0.16 0.11 0.13 0.23 0.21 0.20 0.14 0.14 0.15 0.21 0.13 Eu/Eu· I 0.98 0.72 0.71 0.55 0.98 0.95 1.01 0.95 I 0.94 I 0.711 0.84 0.68 0.53 0.89 0.93 0.94 1.08 1.01 Ua/lblNI 5.5 12.2 3.4 1.3 12.0 24.2 13.4 9.2 I 20.2 I 14.3 9.1 9.6 25.9 12.3 11.2 10.4 3.7 8.9 ..... :======::::::====z:======z======:::c======::::;==a::a:= ••Ez:c: •••::=a::z:zz::===s=====.a===:z:z:======z::& ...... p.. Table D.II. continued. SAFFORD DISTRICT RAJ AND CHRISTMAS DISTRICT Sf 17 Sf21 Sf23 Sf32 Sf33 Sf3~ Sf41 SF43 CHI CHZ R11 R13 R14 Rl.1 RlaZ Rla3 R184 CHl1 CH12 ~======: :===&::=====&===_==&::==:=:&===2.&&&_==&:&&;::= ••••_==a& •••••••••••••••••••••••••• :: ••••====&2.&====:za=====%::&==== •••===::&=a===::==a======_== Sc I 9.55 6.32 9~.19 4.n 5.13 1.78 8.68 27.81 32.08 22.95 24.49 22.74 25.79 8.76 6.89 8.82 8.55 6.95 6.86 Cr I 14.29 6.83 30.37 12.28 22.47 1.90 2.89 32.65 46.51 15.n 11.59 20.25 35.00 27.48 14.16 2.37 0.54 29.04 29.12 Co I 16.32 9.52 12.70 8.15 8.27 4.98 12.15 36.83 38.31 29.85 24.11 23.00 25.21 10.61 8.60 8.04 8.96 14.27 14.66 Hi I 17.79 9.98 19.85 11.03 12.87 1.78 3.60 28.72 34.41 18.13 11.95 14.40 16.52 16.03 12.88 1.19 1.74 24.08 21.31 Cu I 22.52 616.68 51.04 248.97 2381.5 579.04 9.72 4.39 21.89 74.24 60.88 47.00443.16 41.40105.18 3.83 2.48 22.66 32.17 Zn I 70.07 29.96 110.2~ 40.41 42.37 198.76 39.95 159.70 95.119 72.02102.92 84.19 88.83 34.86 35.05 47.35 57.85 63.38 65.49 Go I 17.38 16.43 21.22 17.80 19.12 20.44 18.60 23.56 23.85 11.07 23.113 18.52 18.94 25.49 18.66 18.64 24.50 24.56 21.41 Rb I 22.30 66.01 69.61 58.19 22.67 61.77 28.39 66.36 14.52 10.91 64.82 59.02 55.12 82.05 69.24 33.17 29.42 50.42 48.04 Sr I 749.~ 553.5 563.8 45~.9 390.5 350.6 8~5.0 1435.3 545.3 "9.7 645.9 461.2 438.4 810.3 672.2 655.6 832.2 670.0 648.5 J I 9.48 9.57 12.08 3.28 6.45 6.16 11.42 15.71 10.79 10.37 33.51 28.01 28.98 16.04 16.67 17.10 22.54 8.74 7.29 lr 99.93 114.03 131.65 79.04 88.41 87.47 68.95 71.80 37.95 33.110233.03 179.59 181.57 1'1.17 133.01 105.58 115.47 108.84 105.24 Nb 4.59 5.16 6.82 4.81 5.32 5.70 3.27 3.24 2.08 1.55 12.50 9.00 8.88 10.18 1.14 4.72 7.09 6.39 10.75 "0 0.60 8.70 2.07 0.41 0.70 1.55 0.37 0.64 0.25 0.23 0.65 0.59 0.69 0.25 0.18 0.49 0.28 0.88 0.33 Sb 0.09 0.07 0.60 0.03 0.21 0.19 0.09 0.96 0.13 0.04 0.19 0.03 0.26 0.14 0.04 0.19 0.38 0.07 0.24 Cs 0.80 1.18 2.08 1.12 0.59 1.16 2.64 3.12 0.04 0.43 2.08 2.54 1.80 0.90 1.16 0.66 0.19 0.65 0.42 Ba 657.3 588.7 637.5 972.8 514.3 713.0 449.3 711.6 295.0 230.3 694.2 595.2 555.0 848.8 876.4 479.3 594.3 764.5 703.6 Hf 2.94 3.n 3.83 2.76 2.95 2.82 2.13 1.98 1.22 1.16 6.50 5.26 5.03 4.26 3.82 3.09 3.42 3.36 2.94 h 0.38 0.52 0.511 0.51 0.51 0.55 0.22 0.23 0.36 0.09 1.01 0.64 0.67 0.84 0.65 0.31 0.58 0.49 1.41 \I 0.36 2.40 0.99 0.55 1.78 2.86 0.47 0.36 0.08 0.12 0.46 0.61 0.56 0.09 0.17 0.98 0.21 0.25 6.27 I'b 11.49 4.10 50.06 7.47 6.04 6.15 5.01 13.59 4.n 3.20 12.15 11.35 10.13 5.34 5.95 4.25 5.16 10.43 9.56 Th 3.30 7.05 11.16 6.15 6.44 3.00 2.15 5.93 0.46 0.84 5.83 6.33 5.35 4.63 5.65 3.22 2.49 5.04 4.39 U 1.14 1.81 2.03 0.48 0.72 0.71 o.n 1.76 0.11 0.29 1.11 1.24 1.04 1.14 1.57 0.52 0.52 0.85 0.84 La 111.31 15.3~ 17.48 5.87 9.99 11.12 9.83 18.71 4.39 4.25 29.60 21.08 26.56 19.74 17.55 16.54 16.79 19.n 19.68 Ce I 24.80 33.83 35.27 12.32 20.66 24.80 22.65 37.88 10.50 10.n 65.33 51.61 58.56 43.57 38.46 36.80 37.74 43.04 '1.01 Nd 1'2.70 15.64 16.77 5.62 9.13 10.98 13.09 20.12 7.10 1.15 34.10 28.02 32.02 21.65 111.111 18.57 22.03 18.59 19.55 S.. I 2.58 2.92 3.15 1.01 1.75 2.04 2.81 4.04 1.710 1.77 7.03 6.01 6.04 4.13 3.85 3.83 4.64 3.26 3.22 Eu I 0.96 0.88 0.91 0.55 0.61 0.51 1.09 1.34 0.70 0.70 1.85 1.59 1.68 1.16 1.04 1.18 1.51 0.99 1.03 lid I 2.58 2.66 3.00 ':.98 1.64 1.75 2.80 3.83 2.05 2.09 7.28 6.39 6.61 3.79 3.62 3.70 4.97 2.78 2.64 Tb I 0.33 0.35 0.39 0.11 0.21 0.21 2.02 0.49 0.30 0.31 0.98 0.90 1.04 0.46 0.49 0.52 0.65 0.33 0.43 Ho I 0.37 0.39 0.46 0.13 0.23 0.20 0.45 0.56 0.30 0.42 1.16 1.12 1.20 0.46 0.57 0.64 o.n 0.31 0.36 Er I 1.05 1.13 1.26 0.36 0.68 0.58 1.30 1.58 1.16 1.25 3.62 3.27 3.24 1.72 1.69 1.89 2.39 0.77 0.70 Tm I 0.15 0.17 0.19 0.05 0.10 0.08 0.18 0.23 '0.03 0.18 0.38 0.46 0.54 0.10 0.24 0.28 0.20 0.13 0.16 Tb I 1.02 1.15 1.32 0.40 0.71 0.57 1.26 1.53 1.21 1.25 3.45 3.04 2.91 1. 72 1.12 1.92 2.37 0.92 0.63 lu I 0.15 0.15 0.21 0.07 0.11 0.09 0.20 0.24 0.21 0.19 0.54 0.46 0.51 0.28 0.28 0.30 0.40 0.12 0.14 Eu/Eu· I 1. 13 0.95 0.89 1.67 1.08 0.61 1.18 1.03 I.U 1.11 0.78 0.78 0.81 0.88 0.84 0.95 0.95 0.98 1.05 (La/Yb)NI 7.5 9.0 8.9 9.9 9.5 U.2 5.3 8.3 2.5 2.3 5.8 4.7 6.1 7.8 6.9 5.8 4.8 14.5 21.1 ...... c===::=.=::z=c::tz==z:.=ac=.::z====.=.=•• =.c ••••••••::aK.:lc •••••z:.:: ••••• c. • .c ••••z •••••• c.= •••=.:.==:=c::.:===.::.====a::a: •• =a=a====a==== •• =====:;::a====. "'-J L'l Table D.II. continued. I TOHBS10NE DISTRICT I (HI21. R21 R25 R201 (H31 R31 R32 R33 R34 R41 R42 R51 111 T12 il3 T21 T22 T23 124 ~==:====% ==.a.&~::'= ••:ZZ=.: ••••C:: ••••• IIII •••• aZ&:: ••• &:==.:a.z::: ••••:.== •••••• & ••••••= ••••• :1% ••••: == ••••==z:.a.=z:==a::a=====z:.====az:=====z:.&====az::== Sc 6.34 6.51 3.93 1.63 5.41 4.14 3.25 3.18 2.05 5.43 3.311 4.59 18.21 16.44 15.19 8.92 8.98 9.63 13.61 (r 24.63 4.18 5.70 0.20 20.09 10.49 9.16 4.14 4.21 ' 2.17 2.15 21.92 0.00199.82131.36 10.58 7.BB 7.40 15.06 Co 14.62 1.01 3.13 I.Bl 12.46 5.51 3.80 5.36 0.11 11.62 4.90 9.69 23.49 21.09 24.03 12.99 13.26 14.74 18.31 NI 22.45 2.83 2.88 0.98 11.62 1.42 4.25 5.13 2.25 1 4.15 3.42. 16.31 3.01 15.42 61.89 7.98 8.29 9.53 11.B2 Cu 33.34 3.32 3.53 0.56 26.59 31.03 88.111 141.66 9.88 11.69 II." 22.113 6.11 49.13 47.58 20.04 23.89 20.51 32.09 Zn 67.20 66.89 40.85 25.13 61.59 122.B2 40.95 55.25 6.90 358.22 52.02 64.16 17.28 106.21 99.55 62.17 63.52 50.62 73.37 Ga 21.62 21.50 11.13 14.20 19.20 19.54 111.61 21.~5 19.60 19.30 111.14 16.111 21.19 19.48 20.75 11.82 22.1;0 20.53 Rb 49.14 64.94 88.62 29.27 47.45 107.08 92.45 100.06 144.27 106.91 126.78222.19 22.65 56.59 47.68 125.62 126.40 131.09 113.62 Sr 735.9 662.1 452.1 654.11 660.9 50B.l 314.5 540.7 99.7 259.2 353.1 402.4 620.9 585.0 579.9 530.0 439.8 485.3 506.6 7.80 16.04 9.28 4.42 6.18 6.29 5.67 7.23 10.31 8.47 11.36 10.40 22.29 14.16 13.60 22.02 21.85 21.66 23.07 Zr \'8.65 99.88 92.37 53.11 100.08111.66 96.01116.35 34.01 99.67 99.50105.12 99.63144.29121.59200.56 lB1.18 221.17 203.50 Nb 5.82 7.19 7.11 2.10 5.01 65.81 6.12 7.0B 2.05 6.49 7.03 7.21 4.29 7.65 10.67 9.35 9.95 9.Bl Ho 0.37 0.16 0.09 0.13 0.20 0.31 0.11 0.29 0.11 0.11 0.42 1.41 0.45 0.94 0.71 0.74 0.55 1.21 Sb 0.04 0.14 0.24 0.01 0.00 0.21 0.22 0.00 0.84 0.52 0.48 0.04 0.20 0.07 0.16 0.02 0.07 0.02 Cs 0.64 2.09 2.31 0.81 0.50 3.83 1.34 1.43 1.23 2.95 6.02 1.33 0.76 0.71 0.82 5.05 5.41 4.01 4.30 Ba 181.4 642.5 179.2 B21.5 861.2 789.5 545.4 B36.3 152.2 326.51197.1 863.5 515.11069.1 1092.6 879.6 115.2 B08.1 779.9 Hf 2.86 3.16 3.02 I.B3 3.12 3.30 3.28 3.63 3.19 3.03 3.22 3.211 2.95 4.37 3.89 6.02 5.56 6.23 5.60 Ta 0.42 0.63 0.67 0.55 0.65 0.49 0.57 0.88 I.B5 0.52 0.91 0.55 0.13 0.65 0.48 0.92 0.B3 0.81 0.70 \I 0.28 0.05 0.22 0.13 0.20 0.B8 0.21 0.15 1.95 0.32 0.37 0.31 0.36 0.51 0.75 1.50 0.81 o.n Pb 10.48 8.82 11.01 11.39 11.38 16.31 20.211 17.16 26.84. 22.74 33.91 17.13 4.08 12.15 11.06 15.36 12.71 11.91 13.22 Th 4.72 5.54 3.84 1.65 4.11 4.56 6.95 5.38 16.66' 4.32 4.92 4.10 2.11 5.61 5.50 11.93 13.92 13.55 10.61 u 1.04 1. 16 0.69 0.61 0.99 0.114 1.46 1.02 3.58 1.52 1.59 1.30 0.39 1.30 1.34 I.BII 2.95 2.80 2.811 La 11.62 23.42 14.70 6.74 11.411 11.08 13.35 17.00 7.13 15.09 11.34 19.40 13.44 20.37 21.06 30.52 26.10 31.86 32.07 c. 36.11 4B.Bl 30.06 14.54 36.15 33.B9 27.15 31.34 12.117 14.51 37.70 43.48 31.47 43.51 44.65 63.7Z 59.34 71.79 67.33 Nd 16.25 21.82 B.65 5.34 16.12 IS.70 11.32 16.61 3.34 IS.30 17.011 19.42 18.711 21.51 21.55 211.90 27.15 31.11 30.01 Sm 2.95 3.B5 2.46 1.26 2.85 2.48 1.81 2.99 0.42 2.65 3.16 3.68 4.59 4.24 4.18 5.43 5.15 6.01 5.78 Eu 0.91 1.05 0.79 0.46 0.96 0.711 0.63 0.93 0.09 I 0.16 0.92 1.01 I.S2 1.27 1.27 1.27 1.19 1.40 1.42 Gd 2.59 3.61 2.31 1.17 2.45 2.16 1.59 2.62 0.25' 2.31 2.65 3.011 5.13 4.03 3.93 5.111 5.11 5.97 5.36 Tb 0.29 0.43 0.43 1.60 0.31 0.34 0.28 0.32 0.05 0.29 0.35 0.38 0.76 0.47 0.51 0.65 0.70 0.B4 0.13 Ho 0.27 0.46 0.43 0.19 0.25 0.30 0.25 0.26 0.17 0.31 0.211 0.35 I 0.87 0.44 0.52 0.66 0.79 0.96 0.82 Er 0.14 1.12 1.05 0.53 0.75 0.62 0.51 0.86 0.28 0.92 0.92 0.90 I 2.54 1.43 1.39 2.26 2.33 2.60 2.37 Tm 0.11 0.12 0.21 0.15 0.1' 0.13 0.14 0.01 0.20 0.19 0.34 0.46 0.35 lb 0.69 1.81 1.02 0.75 0.78 0.51 0.54 0.94 0.51 0.69 1.01 0.92 I 2.45 1.36 1.24 2.19 2.33 2.67 2.29 lu 0.11 0.32 0.20 0.13 0.10 0.13 0.13 0.12 0.07 • 0.14 0.14 0.14 I 0.33 0.24 0.19 0.37 0.35 0.44 0.34 Eu/Eu· I 0.99 0.85 1.00 1.14 1.08 1.01 1.12 0.99 0.79 0.92 0.95 0.89 I 0.95 0.93 0.94 0.72 0.70 0.70 0.77 ...... (l./lb)N I 17.3 8.5 9.8 6.1 15.1 20.2 16.7 12.2 10.2 14.11 11.6 14.2 I 3.7 10.1 11.5 9.4 7.6 B.l 9.4 ~ 0\ ======~======:::===:z==s:======&=.===s:a::.======:a=as:ca=_:===z:a.z;::z.::a======a=====z.======::::::.======a:=== Table D.lI. continued. .w\ ~L\"- PRECAMIIRIAN UNITS yj\:>\ 125 1282 12a3 T2a5 T32 1'3 PCA·l PCA·2 ~1 paBA-l PBGS·l PDCA·l Pe6ll-l PLOA-l PRA22a I ==:::::==:;;:3:::::::a====&.&.==& ••a:&=_II •• ====& ••====_.&::I::.1 =•• =aa== ••••a==a •• =-a==aa:::z==:ca===z=ac&&&a= ••••:a=c ••• =a==a== ••= I Sc I 11.38 5.24 3.51 5.66 4.89 2.32 35.40 49.31 6.06 37.24 49.56 32.32 48.59 25.04 21.73 \ Cr \ 6.43 2.39 1.97 3.64 2.43 1.49 54.16 197.52 6.B9 11.51 4.41 17.01 363.36 38.55 26.73 \ Co \ 18.03 3.88 2.88 4.13 2.47 0.03 37.07 48.86 5.84 38.22 22.50 29.02 45.58 30.17 43.33 \ NI \ 10.27 0.84 0.69 0.95 0.44 0.42 56.91 66.94 2.68 24.34 0.78 11.36 90.66 44.36 45.43 I Cu \ 35.73 3.27 3.15 3.07 3.26 0.48 73.35 49.94 3.28 94.93 20.18 44.28 52.22 31.83 48.61 Zn \ 72.86 58.14 37.82 59.80 40.48 35.67 99.18 89.06 63.14 181.23 165.82 84.49 81.90 72.29156.41 Ga \ 19.13 16.29 16.16 15.27 15.05 17.73 15.28 11.54 28.18 17.04 19.11 15.19 15.20 12.12 20.53 Rb \108.66 128.60 44.55 125.67 139.40 247.75 31.93 22.80142.19 21.05 1.68 3.43 3.13 0.28 50.21 Sr \ 434.2 316.7 209.2 262.1 193.4 48.4 173.5 128.1 265.2 173.1 193.9 258.1 165.9 136.1 276.8 Y I 22.77 25.54 23.68 26.02 28.47 18.31 19.29 27.89 14.33 28.19 45.61 19.38 29.86 11.67 42.61 Zr \253.01227.35238.118208.111 185.59 41.9] 65.19 71.911427.77 103.64 41.31 27.91 94.13 71.BI252.36 Nb I 9.29 11.40 12.28 11.41 11.30 19.05 4.21 16.37 2.22 3.29 "0 1.30 0.79 0.311 0.28 0.33 0.80 1.78 0.33 0.61 1.57 1.71 0.41 0.011 0.89 1. 10 Sb 0.04 0.04 0.13 0.04 0.32 0.19 0.21 0.60 0.01 1.00 0.34 0.70 0.35 0.112 0.01 C. 4.92 3.06 2.62 2.32 5.22 8.85 1.00 0.41 2.95 3.02 0.110 0.29 0.34 0.09 16.28 ar. 917.7 1414.9 1001.9 1231.9 1033.5 141.9 127.2 68.7 1609.3 112.7 109.5 123.0 34.0 62.4 408.9 Hf 6.94 6.17 6.58 6.05 5.45 2.42 2.15 2.25 12.03 3.111 1.39 1.12 2.87 2.16 6.67 Ta 0.98 1.19 0.77 1.11 0.92 1.95 0.37 0.34 0.611 0.54 0.40 0.24 0.34 0.47 0.99 \I 1.28 0.70 0.40 0.98 1.04 0.81 0.64 0.34 0.07 0.110 0.52 0.23 0.64 0.71 2.71 Pb 13.34 15.75 10.79 16.90 15.00 13.16 ~ 1.73 3.43 31.61 14.66 2.62 5.05 12.40 1.53 22.12 Th 10.98 10.99 10.31 12.09 11.49 7.29 I 0.35 0.33 17.64 2.37 0.55 0.85 0.88 D." 1.89 U 3.11 2.88 1.83 3.00 2.48 1.33 0.33 0.14 3.36 0.111 0.39 0.41 0.22 0.13 0.54 La 26.92 35.60 27.99 32.88 34.41 8.14 4.16 3.91 170.20 10.17 10.92 4.49 6.83 5.08 2i.82 Ce 57.60 72.62 60.80 66.71 63.47 20.49 11.07 11.18338.66 24.39 30.64 12.30 18.30 13.23 56.08 Nd 26.18 30.93 25.71 29.14 30.00 B.61 8.61 8.73 115.11 13.76 25.07 8.33 11.90 9.51 37.42 SID 5.31 5.43 4.86 5.42 5.1B 2.20 \ 2.60 2.96 15.62 3.51 1.49 2.41 3.55 2.59 9.11 Eu 1.38 1.50 1. 14 1.37 1.25 0.21 \ 0.98 1.10 1.84 1.14 2.71 0.86 1.21 0.92 3.06 Gd 5.25 5.83 4.87 5.31 5.37 2.31 \ 3.53 4.17 11.06 4.47 10.42 3.16 4.89 3.39 10.01 Tb 0.77 0.80 0.70 0.81 0.88 0.37 \- 0.59 0.74 0.96 0.77 1.55 0.53 0.83 0.55 1.45 Ho 0.88 0.95 0.85 0.93 1.03 0.51 \ 0.17 1.04 0.56 1.13 1.83 0.77 1.16 0.69 1.66 Er 2.63 2.86 2.53 2.98 2.96 1.72 \ 2.26 2.92 1.23 3.32 4.90 2.34 3.19 2.04 4.64 TID 0.39 0.49 0.16 I 0.33 0.49 0.18 0.51 0.62 0.35 0.54 0.29 0.65 lb 2.75 3.13 2.66 3.13 2.91 1.86 \ 2.13 2.84 1.02 3.33 3.77 2.34 3.0i! 1.B5 4.14 Lu 0.40 0.45 0.42 0.49 0.49 0.30 I 0.33 0.45 0.19 0.53 0.57 0.36 0.48 0.28 0.65 Eu/Eu· 0.79 0.81 0.71 0.17 0.72 0.28 \ 0.99 0.96 0.41 0.87 0.94 0.95 0.89 0.95 0.91 . (Le/Yb)N 6.6 1.7 7.1 1.1 8.0 3.2 I 1.3 0.9 112.8 2.1 2.0 1.3 1.5 1.9 ..... I 3.6 I '-I ::::======::======a======:===&=::======-=.:••• &2a:~;:;=.===a=:c:======;2======;=====~ '-I Table D.III. Nd-Sm and Rb-Sr isotopic data. Concentration (ppm) Ages in Ha 1 Sarrple Nd Sm Sr Rb 1(143/144)m (147/144)m E(Nd~m E(Nd)T Age T-CHUR T-DH 187Rb/86Sr (87/86Sr)m (87/86Sr)o 1 ------Tombstone District ill 120 .194.77642.94 36.89 I 0.512412 0.142832 -4.41 -3.89 76 640 1350 I 0.166 0.708101 0.707922 1 T21 30 1 .25 5.62 492.87 117.00 I 0.512264 0.112289 -7.30 -6.48 76 676 1180 I 0.687 0.709044 0.708302 I T22 I 30 5.7 462.31 139.25 I 0.512244 0.114834 -7.69 -6.89 76 734 1236 I 0.872 0.70935 0.708409 I T2a5 131.445.78266.19 127.16 I 0.512226 0.111127 -8.04 -7.21 76 734 1220 I 1.382 0.711115 0.709622 I T32 130.36 5.69 201.87 144.93 I 0.512213 0.113364 -8.29 -7.52 72 778 1263 I 2.078 0.711919 0.709794 I T43 I 9.87 2.51 45.42 246.03 I 0.512252 0.15365 -7.53 -7.17 66 1365 1916 I 15.694 0.723221 0.708505 I ------Ray and Christmas Districts CH1 1 7.54 1.85 504.81 450.12 0.512602 0.148343 -0.70 -0.23 76 114 1059 2.579 0.704326 0.704300 Rl1 133.86 6.95 579.50 59.36 0.512113 0.124002 -10.24 -9.57 72 1100 1554 0.296 0.710251 0.709948 R1a2 122.24 4.27 677.02 133.08 0.512242 0.115949 -7.72 -7.00 70 748 1252 0.569 0.707009 0.706444 R1a4 123.06 4.90 795.89 27.87 0.512293 0.128538 -6.73 -6.12 70 m 1337 0.101 0.704507 0.704406 CH11 119.66 3.28 709.30 50.55 0.51227 0.100803 -7.18 -6.32 70 586 1061 0.206 0.705822 0.705617 CH11R 1'8.89 3.2 697 49.8 0.512287 0.102433 -6.85 -6.00 70 568 1054 0.207 0.705857 0.705651 CH14 118.72 3.24 730.2 59.7 0.512273 0.104501 -7.12 -6.30 70 604 1091 0.236 0.706228 0.705993 R21 124.07 4.22 614.46 61.44 0.512292 0.106081 -6.75 -6.00 65 583 1080 0.289 0.706516 0.706249 R2a7 I 5.74 1.12 699.33 31.9 0.512097 0.118304 -10.55 -9.91 64 1052 1492 0.132 0.705212 0.705092 CH31 1'9.333.29680.15 555.08 0.512264 0.102798 -7.30 -6.58 60 608 1086 2.361 0.706019 0.704007 CII32 117.17 2.87 599.5 69.8 0.512268 0.100962 -7.22 -6.48 60 590 1065 0.337 0.706183 0.705896 il31 115.46 2.54 543.68 99.16 0.512196 0.099311 -8.62 -7.88 60 692 1140 0.528 0.708208 0.707758 R32 I 11.4 1.88 408.45 99.15 0.512131 0.099812 -9.89 -9.15 60 798 1225 0.702 0.70795 0.707351 R42 1'9.03 3.36 363.62 132.96 0.512106 0.106644 -10.38 -9.69 60 901 1330 1.058 0.709885 0.708983 ------~------Copper Basin District CBll 123.34 4.37 851.64 29.66 I 0.511905 0.113308 -14.30 -13.51 74 1338 1691 1 0.101 0.704094 0.703988 1 CB23 1'8.562.85 749.14 73.6 I 0.51206 0.092733 -11.28 -10.29 74 848 1242 I 0.284 0.706585 0.706286 I CB31 116.092.78 724.13 74.12 I 0.512117 0.104505 -10.16 -9.32 72 862 1292 I 0.296 0.706555 0.706252 I CB41 .... I 16.8 2.9 1000.9 63.74 I 0.512125 0.10445 -10.01 -9.16 72 848 1281 I 0.184 0.706463 0.706275 1 '-l c:> ---~------Table D.III. continued. Concentration Safford District SF17 114.22 2.85 824.5 24_23 I 0.512631 0.120944 -0_14 0.59 75 14 729 I 0.085 0.704333 0.704242 SF21 117.29 3.19 628.4 75.3 I 0.512371 0.111655 -5.21 -4.46 69 479 1026 1 0.347 0.705751 0.705411 SF32 16.28 1.11 525.53 66.15 1 0.51244 0.106494 -3.86 -3.19 58 335 890 I 0.364 0.70579 0.705490 SF33 111.48 2.08 503.7 56.8 1 0.512439 0.109698 -3.88 -3.24 58 349 916 1 0.326 0.705713 0.705444 SF34 112.18 2.2 372.14 65.96 1 0.512161 0.10937 '9.30 -8.66 58 833 1288 1 0.513 0.707069 0.706647 1 ------Crown King Granodiorite CKl 124.43 3.97 936 52.1 I 0.512041 0.098176 -11.65 -10.84 64 924 1319 I 0.161 0.70681 0.706664 1 ------Bagdad District B22 116_70 2.99 154.23 108.02 0.51202 0.108187 -12.06 -11.17 78 1064 1463 1 2.028 0.716031 0.713784 1 B33 142.35 7.34 859.87 90.70 0.511961 0.104737 -13.21 -12.30 77 1122 1496 1 0.305 0.710191 0.709857 1 B3al 129.83 4.95 463.1 134.04 0.512068 0.100292 -11.12 -10.17 77 901 1309 I 0.838 0.711547 0.710631 I B3bl 126.634.40 565.80 107.14 1 0.512082 0.099805 -10.85 -9.88 78 875 1286 I 0.548 0.708859 0.708252 I B42 131.07 5.21 529:54 111.38 I 0.51204 0.101367 -11.07 -10.75 75 956 1355 I 0.609 0.710265 0.709616 I B51 128.35 4.75 598.45 114.81 I 0.512017 0.101266 -12.11 -11.22 73 992 1383 I 0.555 0.710049 0.709473 I B61 122.163.40 287.48573.05 1 0.511968 0.092778 -13.07 -12.11 72 983 1350 I 5.772 0.716663 0.710759 I Diamond Joe Stock 011 125.884.14 749.70 62.02 1 0.511963 0.096787 -13.17 -12.25 72 1030 1399 0.230 0.709788 0.709553 031 120_003.64 450.06 101.97 I 0.511894 0.109904 -14.51 -13.71 72 1305 1655 0.656 0.711608 0.710937 ..... '-I \0 Table D.III. continued. Concentration (ppm) Ages in Ha Sa/lllle Nd Sm Sr Rb 1(143/144)m (147/144)m E(Nd)m E(Nd)T Age T-CHUR T-DH 187Rb/86Sr (87/86Sr)m (87/86Sr)o ------._------Sierrita District (data from Anthony and Titley (1988» SI1 I 27_84.95 612.12 115.96 I 0.512381 0.107474 -5.01 -4.25 67 440 976 I 0.557 0.70739 0.706860 I Sla2 3 1 2.52 5.85 630.05 112.79 I 0.512223 0.10869 -8.10 -7.33 68 719 1198 I 0.522 0.708834 0.708330 I S23 115.87 4.26 88.35 125.87 I 0.512261 0.162199 -7.35 -7.07 65 1662 2166 I 4.124 0.712118 0.708310 I 531 20 1 .64 3.39 438.17 138.81 I 0.512265 0.09936 -7.28 -6.49 63 585 1055 I 0.8n 0.708485 0.70nOO I S41 124.093.96397.16265.02 I 0.512164 0.099299 ·9.25 ·8.52 58 742 1179 I 1.931 0.710751 0.709160 I S43 123.78 3.83 I 0.512173 0.1 -9.07 -8.35 58 734 1175 I 1.942 0.7106 0.709000 I ------Precambrian Basement Samples PCGN·l 1112.0 14.8 271.77 143.84 I 0.511326 0.079996 -25.59 0.35 1740 1709 1913 1 1.536 0'{59655 U.IU1229 I PCGH·1R 1112.3 14.9 275.25 146.8 I 0.511363 0.08015 -24.87 1.04 1740 1664 1876 I 1.548 0.739588 0.700862 I PCA-2 I 9.68 3.1 138.62 23.45 I 0.512851 0.193946 4.15 4.n 1740 1427 I 0.490 0.713252 0.701li02 I PBBA-l I 14.6 3.8 178.32 22.19 I 0.512327 0.155997 ·6.07 2.98 1740 1164 1812 I 0.360 0.710274 0.701267 I PJG-l 110.11 2.77293.44 3.76 I 0.512538 0.165724 -1.95 5.01 1760 493 1557 I 0.037 0.703471 0.702533 I PIOA·l 114.65 4.08 211.45 2117.8 I 0.512566 0.168387 -1.40 4.74 1700 388 1555 I 28.963 0.703657 ·0.004018 I PDCA·l 1 13.93.75 186.1 666.3 I 0.512573 0.163305 -1.27 5.99 1700 297 1403 I 10.362 0.712097 0.458911 I ------Data From Productive laramide Districts From Farmer and DePaolo (1984) Hin Parle 1 33.4 5.51 120 232 I 0.511165 0.0999 -13.32 -12.42 73 1074 1454 I 5.583 0.71806 0.712270 I Bagdad I 5.5 0.88 365 250 I 0.511227 0.0962 -12.11 -11.15 75 940 1337 I 1.976 0.71418 0.712074 I Ajo I 36.3 5.34 535 122.8 I 0.511437 0.089 -8.01 -7.12 65 581 1026 I 0.663 0.70854 0.707928 I Ajo I 23.5 4.09 593 54.6 I 0.511373 0.1055 -9.26 -8.50 65 793 1254 I 0.266 0.70782 0.707574 I Silverbelll 22.33.65 403 148 I 0.511379 0.099 -9.14 -8.34 64 731 1180 I 1.061 0.71109 0.710125 I Sierrita I 18.72.95 360 In.2 I 0.511404 0.0954 -8.65 -7.84 63 667 1117 I 1.423 0.7097 0.708426 I Lakeshore I 20 3.7 644 128.3 I 0.511361 0.1121 -9.50 -8.79 65 876 1345 I 0.576 0.70953 0.708998 I Morenci I 8.16 1.53 540 ln I 0.511498 0.1138 ·6.82 -6.13 65 642 1174 I 0.945 0.70805 0.707177 I San Hanuel I 193.17 527 77.7 I 0.511491 0.1007 -6.96 -6.10 70 566 980 I 0.427 0.70879 0.708365 I ------...... OJ 0 Table D.IV. Modal mineralogy of samples. BAGDAD DISTRICT I DIAMOND JOE STOCK Sunple 021 U22" Ul2 BB UJ4 835 B36 83.1 83bl B3b2 83b] 83b4 842 B51 B52 861 I 011 012 013 014 021 022 031 ~..;.&:.c K.C:'=- _1_K:aa::.az.c:::: a ~;a=:a :::::::::ca::::c:;..a •• 3C:::: ••• :::::=a.c::::.;. ;,;:.aZC2 .::c::::ca== •••••••••• c •••••• c ••••••••••2c ••• a:o::::. •• ===-1 =a=a=== ••• ======.: =::c =::.:: c:. ,;...; =••• .:::::=-.z== quartz 50 *57.4 15.2 6.6 16.9 8.4 8 28.7 26.4 27.2 23.8 12 3.3 *21.4 *25.5 "IT.4 30 21.9 19.1 21.6 *25.1 *28 *lO.S K feldspar 30 *37.4 21.2 8.8 21.4 3.4 16.8 29.4 21.9 17.2 22.2 12.2 22.1 29.4 16.7 *28.3 14.3 16.4 20.6 16 8 9.8 *19.8 plagioclasel 20 *5.2 *49.8 57.6 46.3 *65.3 52.6 *29.6 39 *45.2 43 51 *53.2 *34.1 *46.3 30.8 45.7 54.2 48.6 50.5 *55.2 *42.1 *48 biotite I 7 7.2 7 15.3 10 11.9 3.3 *7.4 7 7.2 *!9 *8.8 *7.3 1.3 6.4 5.7 6.6 8.6 *6.6 *17 *1.5 hornblende I 0.4 14 2.3 4.3 9.2 7 1 2.4 14.8 *1:2 1 1.2 P 1.9 1.1 *1.5 P pyroxene I 3.8 2 4.1 1.2 opaques I P 2 3 1.6 2.6 2 0.2 1.4 1.4 1.2 2.4 *1.2 0.4 *2.2 *0.2 0.4 1.1 1.8 1.1 *2.5 *1.8 0.1 apatite I 0.4 0.8 0.4 0.7 0.2 0.1 0.3 0.2 P P P P 0.6 "P 0.5 0.3 0.6 P *0.3 *0.3 0.1 zircon I P P P P 7 0.1 P P P P p P P P P P P P P P allani te I 7 P P P titanite I 0.2 P 7 0.7 0.4 0.4 0.4 0.4 1.5 0.4 0.8 1. 1 ·0.8 ·1 X Phenos I o 13 8 o 10 3 0 5 o 12 0 0 35 37 40 52 000 o 33 30 63 X Hatrlx I 100 87 92 100 90 97 100 95 100 88 100 100 65 63 60 4B 100 100 100 100 67 70 37 ======::_=====c======::::=::::;===:==_==a:;;.a2:_=====:======:====== Table D.IV. continued. I IC. KINGI COPPER BASIN DISTRICT I COPPER CREEK DISTRICT Sa""le I 032 033 041 042 051 I CKI I c811 C821 C822 C823 CB31 C841 IC13** C12 C21 e22 01 C41 C43 C44 C4S ======I :: ======:====_====_:l:a:_= I ==z==== I =~======_.::===:=za& ••aa:zza.az= I co:z:::: ===:=:=:======:==:= ==::a::====::=:= quartz *12.8 "31 27.5 26 28.5 21.1 I "2.4 7 24 23.4 *26.7 *22 I 40 30.6 25.4 *28.6 26.4 "30.7 "7.9 "7.8 K feldspar 13.2 22.2 40.3 36.2 38 14.6 I 15.7 22 18 20.B 15 I 49 22.1 19.2 39.2 20.6 13.9 6.6 2.6 plaSiloclasel *70.2 38 28 37.2 31.5 "57.2 1"55.7 13.3 *45 *50.11 *43.6 *55 I *41 10 39.6 44.6 "29.4 *40.4 *20.9 *63.9 *58.7 bIotite I 2.4 1.8 P "3.9 I *1 1.5 II *6.8 *7.5 *6.3 I 7.1 10 *2.4 B.2 "28.4 "16.7 *29 hornbl ende I nu 0.8 I!IJ 0.4 nu 3.8 nu 0.6 nu 2.0 1. 7 I "40 *0.5 1 "4B *3.6 "2.3 *0.1 pyroxene I I I lin 3.4 opaques I 0.6 0.6 0.4 P P 0.4 I 0.8 2.5 1.2 1.6 *1.4 1 I ·11 ·1 0.6 0.8 0.4 2 ·2.6 1.5 apatite I P P P P 0.3 I 0.6 P 0.2 P P "0.2 I P P P P 0.5 "P 0.3 zircon I P P ? P I P P P P P 1 P P P P P allanite I 0.2 I I P P titanite I 0.6 I I X Ph enos I 15 20 0 o o o I 10 o 5 0 40 32 I 12 1 0 22 13 11 3D 22 14 X Hutrlx I 85 80 100 100 100 IUD I 90 100 95 100 60 68 I 88 99 100 711 87 89 70 78 86 ...... (Xl Table D.IV. continued. RAY AND CHRISTIIAS DISTRICTS Sanple ICH1*' CH2*" CHal*" Rll R13 R14 CHll CH12 CH13 CH14 RIal Rla2 Rl.3 RIal, R21 R2a4 R25 R26 R2al CH3l" CH32 R3l ======I ======z=====a==a==a:====a:====.a:a==a:=====s=====:z======s======a:======quartz 1 *0.8 *1.0 3.9 3.9 15.1 *9.6 *13.9 3.5 *6.2 *23.2 *39.9 10 13.6 31.2 3.2 *39.5 *25.2 *42.1 *23 *19.5 *29.3 Ie feldspar 1 4.8 9.2 3.1 23.8 21.1 1.1 8.4 12.6 10.2 12 10.3 5.8 13 *19.6 1.4 8.1 *25.3 plagioclasel"93.6 *83.3 "51.9 61.9 *54.2 *48 *47.2 *45.8 *55.3 *67.7 *51.9 *48.5 59 56.7 42.8 48.4 42 *46.8 *37.1 *28.5 *57.9 *30.8 biotite 1 11 12.4 *15.8 *8.5 *6.5 *7.4 *8.1 *6.4 13.6 12.8 4.5 *1.3 *8.8 *31.8 *14.4 *13.3 hornblende I *34.9 14.4 *8.4 *9.1 *28.8 *8.5 *3 *3.7 3.2 13.3 2.2 36.4 *8.1 pyroxene I "4.8 *12.1 13 *15.2 P 5.2 IIJ.J 0.8 opoques I "0.8 *4 "5.1 3.4 4.8 2.3 *2.5 "1.8 3.8 *1.5 0.6 2.2 3 0.8 1 0.2 0.3 "0.5 *1.7 0.1 *1.3 apati te I "0.5 2 0.3 0.1 p p 0.2 *.5 0.2 0.1 p 0.4 0.5 p p 0.2 p P p p zircon I P 0.3 P P P P p p P p P P P P P P p alieni te I ? p P P 0.1 p t hanh. I p p 0.3 0.6 0.1 0.3 0.5 1.6 0.8 P P 0.3 0.5 P X PhenOl I 63 20 42 o 12 6 47 43 1 47 61 54 o o o o 15 39 58 46 59 55 X Matrlll I 31 110 511 100 88 94 53 51 93 53 39 46 100 100 100 100 85 61 42 54 41 45 II _II;; I; C E:;: c==~=.; __ .;: ;&;as= •• .-_:cc.aC;;Il •• 2oa ••••••••• D.= •• ~.;_cca "= •• ••••a ••••••••••• SO •••••••••••••• =.:zE.c===a ••• == ••• aa.II==:z ===:11::===:;::::::':'====_======:;:::: -~ Table D.IV. continued. I I SAFfORD DISTRICT SilIl"le 1 R12 R13 R41 R42 R51 I Sf15 SF16 SF17** Sf21 Sf23 Sf32 SF33 Sf34 SF41 SF43 pll*" Tt2 Tt3 T21 T22 T23 T24 ==a======I.:::a ::a====: =:a ===::a.: ==:.a az:. :::=:.&aa= I :::aca.= :az z. =:&======a= == •••• =...... = ••••••••••• == ••• a===a 8;:' a:::: I ~ s:a:==c ca. z:=: aa:=::::_: ====a. z: == a.:&.::::;: =~: a== qu.ru 1"17.4 "36 *14.3 *18.9 *11 I 1 "4.2 24 *13.2 *11.9 *22.2 *28.9 3.1 *9.6 *15.5 11.6 15.1 12.7 14.2 K feldspar 1*29.9 *14.9 *8.7 *0.7 51 I ? ? 4 *17.2 *111.5 12 10.4 3.4 4.5 26 24.4 23.9 26.5 28.2 plagioclasel *46 *40.5 *67 *66.4 *29.1 1*51.4 *12.2 "85 *49.3 *60.6 *45.11 *52.5 *53.5 *69.7 *75 *100 *63.2 *51.9 45.8 47.9 42.8 43.2 biotite I *6.2 *8.3 "9.1 *6.3 *1.5 I 24.5 15.8 21 6.2 *15.4 *11.8 *6.4 *11.5 *4.8 4.6 5.1 5.8 3.4 hornblende I *1 *0.3 1 *4.2 *5.8 0.8 *18.2 5.8 5 pyroxene I I *P *11 ? *11.3 0.2 p 8.2 8 opaques I 0.5 0.3 "0.3 *0.1 P 1*12.9 2 *4 1.1 1.8 2.1 *1.5 *O.B *5.4 *12.7 *p 11.2 *1.3 1.6 1.8 3.8 3 apat i te I P P P P piP "P P p 0.4 0.2 P P *0.2 P p *p P P P P zircon I P P P pip P p P p p P *P P P allanite I P ? I p t i tani te I *p p 1 ep'ol 1 P P 0.2 X Phenos I 59 47 55 55 15 I 30 21 38 0 21 44 55 60 22 64 11 48 o o 0 o X Matrix I 41 53 45 45 85 I 70 19 62 100 19 56 45 40 18 36 89 52 100 100 100 100 ======;:======::;;==~==a.Z:" ••1I:a=&======:======a======...... co N Table D.l:V. continued. TOMBSTONE DISTRICT Saaple T25 T2a2 T2a3 T2a5 131 132 T44 ====:1::'==== I=====a====::======:.:====::z====z&zaz:=a:..a:.== quartz 11 *13.6 *8.7 *31.6 *17.7 *20.8 *26.2 I( feldspar I 17.2 *35.8 21.4 *33.3 7.8 31 *66.1 plagioclase 56.4 *40.9 *51.7 *32.8 *68.5 *45.5 *4.7 biotite 7.G *7.5 *6.1 *1.9 *5.4 *2.7 *3 hornblende *8.6 pyroxene 4.2 opaques 3.2 *2.2 *1.5 ·0.4 *0.6 P apatite 0.4 *P P *p P P P zircon P *p .p P all ani te IIlOnal 1 .p 1 titanite X Phenos 0 53 18 45 48 38 12 X Hatrix 100 47 82 55 52 62 88 .=v~.=c •• a=::' •••J:I •••• c•• ==.=c:===c:aa •••••••••& •••••••••••••J: ••=a==a=c:======••:c •••==== * = minerai phase iii present as (but not neceaurlty only as) a phenocryst. ** • 8a""le. In .. hlch only tha phenocryst pha.ea ara listed because of an apanltlc matrix. P " the minerai phase la pruent In very amall amouna, Ululllly <0. tX. 1 • uncertain Identification of minerai phlse, usually due to It. fine grain size. Abbreviations: lIlJ = muscovite; ep • epidote; 01 • olivine; manu " monazite. .... CO W 184 Table D. V. Rock names of samples according to IUGS classification. sampla Rock Nam. sample Roeli: Nam. Tll andesite Tl2 porphyritic =~-qtz andesite SFJ4 bt granodiorite porphyry TlJ porphyritic =~-qtz andesite SF4l porphyritic hbl diorite T2l bt-hbl quartz ~onzodiorite SF43 pyx andesito/basalt porphyry T22 hbl-bt quartz ~onzodiorite CHl bualt porphyry T2J bt-pyx quartz ~onzodiorite CH2 porphyritic pyx basalt T24 pyx quartz monzodiorite CHal porphyritic hbl diorite T25 pyx quartz ~onzodiorite CHll porphyritic bt-hbl quartz monzodiorite T2a2 bt quartz monzonite porphyry CH12 bt-hbl quartz monzodiorite T2a3 porphyritic =t-hbl quartz monzodiorite ClUJ hbl quartz monzodiorite T2a!5 porphyritic granite CH14 porphyritic bt-hbl quartz monzodiorite Tll porphyritic bt granodiorite Rll bt-pyx quartz diorite T32 porphyritic granite Rl3 porphyritic bt-pyx quartz T44 porphyritic granite monzodiorite C12 rhyolite Rl4 porphyritic hbl-bt tonalite/ quartz diorite C13 porphyritic andesite Rlal bt granodiorite porphyry C2l bt granodiori~a lUa2 hbl-bt tonalite porphyry C22 bt granodiori~e RlaJ bt quartz monzodiorite Cll porphyritic g=anite Rlll4 hbl quartz monzodiorite C41 porphyritic =~ granodiorite R2l bt qranodiorite C43 porphyritic bt granite R2a4 pyx-hbl quartz monzodiorite C44 porphyritic bt quartz monZOdiorite R25 porphyritiC bt granodiorite C45 porphyritic bt quartz diorite R26 porphyritic bt granodiorite SFl5 porphyritic hbl-qtz-bt R2a7 bt granodiorite porphyry andesite CHJl porphyritic hbl-bt tonalite SFl6 porphyritic r~l-bt andesite CHJ2 bt granodiorite porphyry SFl7 porphyritic pyx andesite RJl bt granodiorite porphyry SF2l bt tonalita R32 bt quartz monzonite porphyry SF23 porphyrltic b~ quartz monZOdiorite Rll porphyritic bt granodiorite SFJ2 porphyritic bt granodiorite/ R41 bt quartz monzodiorite porphyry monZOdiorite R42 bt-hbl tonalite porphyry SFJ3 bt granodiori~e porphyry RSl porphyritic quartz ~onzonite 135 Tallle D.V. continued. sample Rooil: Nll.llle sample Rock Name 011 bt granodiorite CRl granodiorite 012 bt granodiorite B21 granite/rhyolite 013 bt granodiorite/monzodiorite B22 porphyritic granite/ rhyolite 014 bt granodiorite B32 porphyri tic bt quartz 021 porphyritic bt granodiorite monzoaiorite 022 porphyritic bt granodiorite B33 bt-hbl quartz monzodiorite on granodiorite porphyry B34 porphyritic pyx-bt grano diorite/quartz monzonite 032 porphyritic quartz monzodiorite B35 hbl-bt quartz diorite/ monzodiorite 033 porpbyritic granite/ granodiorite B36 hbl-bt quartz monzodiorite 041 granite B3al bt granite 042 granite B3b1 hbl granite/granodiorite 051 granite B3b2 porphyritic bt granodiorite CBll porpbyritic hbl diorite B3b3 bt granodiorite CB21 quartz syenite (kspar B3b4 bt-hbl quartz monzodiorite nooded) B42 porphyritic bt monzodiorite CB22 bt granodiorite CB23 bt granodiorite BSl porphyritic bt granite CBn porphyritic bt granodiorite B52 porphyritic bt granodiorite CB41 porphyritic bt granodiorite B61 granite porphyl.-Y Abbreviations I bt. biotite: hbl a hornblende: pyx = pyroxene: qez - quartz. Abbreviations are used for nama modifiers only; rock name based on lUGS classification is written 1n full. 186 APPENDIXE EQUATIONS AND PARTITION COEFFICIENTS USED IN MODELING In this section the various methods used to model the behavior of trace element and isotopic data are detailed. The mineral-melt partition coefficients utilized in this study are listed for both acid and basic melt compositions in Table E.I. Fractional Crystallization This process is modeled as Rayleigh fractionation by the equation: (1) 1 1 where F is the fraction of liquid remaining, and '1. and '1. ,0 are the concentrations of an element i in the final and initial magmas, respectively. The bulk distribution coefficient, D, is dermed as: (2) where ~/ is the solid/liquid distribution coefficient for element i in fractionating mineral phase j, and Xi is the weight fraction of mineral j removed from the melt. Compatible elements have K values greater than 1.0 and incompatible elements have D values less than 1.0. Batch Partial Melting This process is described by the equation: (3) where F, K, G., and '1.0 are the same as defined for fractional crystallization. Assimilation-Fractional Crystallization (AFC) The equations describing the process whereby assimilation of foreign material is accompanied by fractional crystallization in a magma, the AFC process, were developed by DePaolo 137 (1981a) to which the reader is referred for the complete derivation of the equations. The AFC equations may be applied to trace element-trace element, isotope ratio-trace element, or isotope ratio-isotope ratio relationships. For a trace element the process is described by the equation: (4) where CL is the concentration of the trace element in the fmal, contaminated magma, CL 0 is the initial concentration of the trace element, D is the bulk distribution coefficient as defmed above, Cc is the concentration of the trace element in the contaminant, and r is the ratio of the rate of assimilation to the rate of fractional crystallization. The parameter f is defmed as: r = ~-(r - 1 + D)/(r - 1» (5) where rand D are the same as above and F is the fraction of the original mass of the magma remaining. In the case where r equals zero there is no assimilation and equation (5) reduces to equation (1). When r equals one, equation (5) is equivalent to zone refining. The effect of AFC processes on radiogenic isotope ratios is described by: (6) O 6 where fL ' fL ' and fc are the isotopic ratios, such as 87 Sr1 Sr or ENd for the contaminated magma, the initial magma, and the contaminant, and CL0, CL, and f are as defined above. Simple binary mixing is a special case of the AFC process in which no fractional crystallization occurs as two isotopic endmembers A and B undergo bulk mixing. This mixing can be described by the equation: {(XA*CA*~) + (XB*CB*EB)) Em x = __ •••• _••••••••••• _•••••• (7) [(XA*CA) + (XB*CB)) where 1-olx is the fmal isotopic ratio in the mixture, t and (3 are the isotopic ratios in endmembers A and B, X" and xB are the weight fractions of A and B in the mixture, and rf and cB are the 188 concentrations of the element of interest in endmembers A and B. The relationship can be solved for two different isotope ratios, or parameters based on such ratios, e.g. ENd and Sro' where it defines hyperbolic mixing trends. Only when the concentrations of the two elements are the same in each endmember will a straight mixing line result. leg Table E.I. Mlneral-meltpartltlon coefficients for acid and easlc compositions used in modeling calculations. Partillon Coefficients tor Acid Compositions mt 01 opx cpx hbl bt pi kspar zir ap titan gt allan monaz Refs 2.5.7 1.5.7 1,5,7 1,5,7 1,5-7 1,5,7,9 ',5.6,9 1,5.9 1.5 4.10 3,6 1.5.7 8 11,12 La 0.66 0.11 0.20 0.25 0.032 0.28 0.03 2.3 26 36 0.26 1250 3200 Ce 0.71 0.15 0.50 0.899 0.037 0.24 0.044 2.64 34.7 53.3 0.35 1032 3413 Nd 0.93 0.22 1.11 2.8 0.044 0.17 0.025 2.2 57.1 88.3 0.53 642 3726 Sm 1.2 0.27 1.67 3.99 0.058 0.18 0.18 3.14 62.8 102 2.66 292 2859 Eu 0.91 0.17 1.56 3.44 0.145 2.11 1.13 3.14 30.4 101 1.5 125 228 Gd 1.25 0.34 1.85 5.98 0.082 0.09 0.011 12 56.3 102 10.5 133 2144 Tb 1.3 0.4 1.89 6.09 0.09 0.088 0.008 29 53.2 91 19.5 ~OO 1786 Er 0.67 0.65 1.80 5.94 0.162 0.084 0.006 135 37.2 58.7 42.8 22 595 Yb 0.44 0.86 1.58 4.89 0.179 0.077 0.012 270 23.9 37.4 39.9 16 273 Lu 0.3 0.90 1.54 4.53 0.185 0.062 0.e06 323 16 27 29.6 13 174 K 0 0.0023 0.037 0.OB1 5.63 0.18 1,49 0.02 Rb 0 0.0027 0.032 0.014 2.75 0.045 0.34 0.008 Sr 0 0.0085 0.516 0.22 0.12 3.6 3.87 0,015 Sa 0.1 0.0029 0.131 0.044 8.00 0.33 6.12 0.017 Zr 1.5 0.075 0.04 0.55 0.60 0.8 0.10 0.05 5 9.72 0.50 HI 0.5 0.04 0.04 0.55 0.70 2.1 0.15 0.03 2.5 16.94 0.50 ", 0.2 0.035 0.002 0.30 0.10 0.31 0.05 0.02 2 24.78 0.005 1000 Sc 10 0.35 1.2 3.1 10 11.3 0.10 0.025 2.49 1 Co 40 3.8 3.2 1.5 3.8 2B.S 0.20 0.27 1.9 NI 16 13 6.6 4.0 12 15 0.20 10.34 0.8 Partition Coefficients for Basic Compositions La 0.05 0.0068 0.019 0.09 0.145 0.035 0.14 14.5 36 0.008 Co 0.064 0.0069 0.024 0.15 0.200 0.034 0.12 16.6 53.3 0.028 Nd 0.092 0.0066 0.033 0.31 0.330 0.032 0.081 21 88.8 0.068 Sm 0.12 0.0066 0.054 0.50 0.52 0.031 0.067 20.7 102 0.29 Eu 0.15 0.0068 0.054 0.51 0.59 0.03 0.34 14.5 101 0.49 Gd 0.171 0.0077 0.091 0.61 0.63 0.03 0.063 21.7 102 0.97 Tb 0.193 0.0087 0.12 0.65 0.63 0.03 0.062 19.5 91 2.07 Er 0.253 0.011 0.23 0.65 0.55 0.034 0.063 14.1 58.7 6.56 Yb 0.300 0.014 0.34 0.62 0.49 0.042 0.067 9.4 37.4 11.5 Lu 0.322 0,016 0.42 0.56 0.43 0.046 0.066 7.9 27 1'.9 K 0.05 0.0068 0.014 0.038 0.96 5 0.17 0,015 Rb 0.25 0.0096 0.022 0.031 0.29 3.06 0.071 0 0.042 Sr 0.05 0.014 0.027 0.12 0.46 0.081 1.83 2 0.012 Sa 0.10 0.0099 0.013 0.026 0.42 1.09 00.23 0.01 0.023 Zr 10 0.025 0.04 0.30 0.35 0.02 5 9.72 0.25 HI 0.20 0.025 0.04 0.30 O.SO 0.02 2.5 16.94 0.25 ", 0.05 0.002 0.002 0.D1 0.03 0.02 2 24.78 0.001 Sc 10 0.35 1.2 3.1 2.1 0.03 0.22 2.49 1 Co 40 3.8 3.2 1.5 3.8 0.10 0.0010.27 1.9 NI 16 13 6.6 4 12 0.26 0 10.34 0.8 ======S Wilson (1989) 'Arth (1976) g Nash and Crecraft (1 (l85) 2 Bacon and Drultt (1988) • Anthony (19B6) ,. Nagasawa and SchnetzJer (1971) 3 Simmons and Hedge (1978) 7 Allegre et al. (1978) 11 Charoy (1966) • Nagasawa (1970) • Gromet and Sliver (1983) 12 YUrlmoto et al. (1990) Abbreviations: mt " magnetite: 01 " olMne: opx " orthopyroxene: cpx = clinopyroxene: hbl " hornblende: pi = plagioclase: kspar " potassium feldspar: zir " zircon: ap " apatite: titan ., titanite: gt " garnet: allan = allanite: rnonaz " monazite. 190 REFERENCES Allegre, C. J., Treuil, M., Minster, J. F., Minster, B., and Albarede, F., 1977, Systematic use of trace elements in igneous processes. Part I: Fral:tional crystallization processes in volcanic suites: Contrib. Mineral. Petro!., v. 62., p. 57-75. Anders, E., and Grevesse, N., 1989, Abundances of the elements: Meteoritic and solar: Geochim. Cosmochim. Acta, v. 53, p. 197-214. Anderson, C. A, 1968, Arizona and adjacent New Mexico: it, Ridge, J. D., ed., Ore deposits in the United States 1933-1967: Amer. Inst. Min. Metall. Petrol. Engs., York, Pa., p. 1163-1190. Anderson, C. A, Scholz, E. A, and Strobell, J. D., Jr., 1955, Geology and ore deposits of the Bagdad area, Yavapai County, Arizona: U. S. Geo!. Sur. Prof. Pap. 278, 103p. Anderson, P., 1989, Proterozoic plate tectonic evolution of Arizona: in Jenney, J. P., and Reynolds, S. J., eds., Geologic evolution of Arizona: Ariz. Geol. Soc. Dig., v. 17, p. 17-56. Anthony, E. Y., 1986, Geochemical evidence for crustal melting in the origin of the igneous suite at the Sierrita porphyry copper deposit, southeastern Arizona: unpub. Ph.D. diss., Univ. of Arizona, Tucson, 89p. Anthony, E. Y., and Titley, S. R., 1988, Progressive mixing of isotopic reservoirs during magma genesis at the Sierrita porphyry copper deposit, Arizona: Inverse solutions: Geochim. Cosmochim. Acta, v. 52, p. . Arcuius, R. J., Ferguson, J., Chappell, B. W., Smith, D., McCulloch, M. T., Jackson, I., Hensel, H. D., Taylor, S. R., Knutson, J., and Gust, D. A., 1988, Trace element and isotopic characteristics of eclogites and other xenoliths derived from the lower continental crust of southeastern Australia and southwestern Colorado Plateau, U.SA.: in Smith, D. c., ed., Ecolgites and eclogite-facies rocks, Developments in Petrology Volume 12, Elsevier, p. 335- 386. Arndt, N. T., and Goldstein, S. L., 1987, Use and abuse of crust-formation ages: Geology, v. 15, p. 893-895. Arth, J. G., 1976, Behavior of trace elements during magmatic processes -- A summary of theoretical models and their applications: Jour. Res. U. S. Geo!. Sur., v. 4, p. 41-47. Asmerom, Y., Patchett, P. J., and Damon, P. E., 1991, Crust-mantle interaction in continental arcs: inferences from the Mesozoic arc in the southwestern United States: Contrib. Mineral. Petro!., v. 107, p. 124-134. Bacon, C. R., and Druitt, T. H., 1988, Compositional evolution of the zoned calcalkaline magma chamber of Mount Mazama, Crater Lake, Oregon: Contrib. Mineral. Petro!., v. 98, p. 224- 256. Baldwin, J. A, and Pearce, J. A, 1982, Discrimination of productive and nonproductive porphyritic intrusions in the Chilean Andes: Econ. Geo!., v. 77, p. 664-674. Ball, T. T., 1982, Geology and fluid inclusion investigation of the Crown King breccia pipe, Yavapai County, Arizona: unpub. M. S. thesis, Colo. Sch. Mines, Golden, 135p. 191 Banks, N. G., Cornwall, H. R., Silberman, M. L., Creasey, S. C., and Marvin, R, F., 1972, Chronology of intrusion and ore deposition at Ray, Arizona - Part I, K-Ar ages: Econ. Geol., v. 67, p. 864-878. Banks, N. G., and Stuckless, J. S., 1973, Chronology of intrusion and ore deposition at Ray, Arizona - Part II, fission-track ages: Econ. Geol., v. 68, p. 657-664. Banks, N. G., and Krieger, M. H., 1977, Geologic map of the Hayden quadrangle, Pinal and Gial Counties, Arizona: U. S. Geol. Sur. Geol. Quad. Map GQ-1391, 1:24,000, 15p. text. Barovich, K. M., 1991, Behavior of LU-Hf, Sm-Nd and Rb-Sr isotopic systems during processes affecting continental crust: unpub. Ph.D diss., Univ. of Arizona, Tucson, 147p. Barter, C. F., and Kelly, J. L., 1982, Geology of the Twin Buttes mineral deposit, Pima mining district, Pima County, Arizona: in Titley, S. R., cd., Advances in geology of the porphyry copper deposits, southwestern North America: Univ. of Arizona Press, Tucson, p. 407-432. Barton, M. D., 1990, Cretaceous magmatism, metamorphism, and metallogeny in the east-central Great Basin: in Anderson, J. L., ed., The nature and origin of Cordilleran magmatism: Geol. Soc. Amer. Memoir 174, p. 283-302. Beane, R. E., and Titley, S. R., 1981, Porphyry copper deposits, part II. hydrothermal alteration and mineralization: Econ. Geol., 75th Anniv. Vol., p. 235-260. Bennett, V. C., and DePaolo, D. J., 1987, Proterozoic crustal history of the western United States as determined by neodymium isotopic mapping: Geol. Soc. Amer. Bull., v. 99, p. 674-685. Blacet, P., 1983, Geology of the Bagdad mine: Cyprus Bagdad Copper Company private rcport, IIp. Black, L. P., and McCulloch, M. T., 1990, Isotopic evidence for the dependence of recurrent felsic magmatism on new crust formation: All example from the Georgetown region of Northeastern Australia: Geochim. Cosmochim. Acta, v. 54, p. 183-196. Blake, D. W., 1971, Geology, alteration, and mineralization of the San Juan mine area, Graham County, Arizona: unpub. M.S. thesis, Univ. of Arizona, Tucson, SSp. Bolin, D. S., 1976, A geochemical comparison of some barren and mineralized igneous complexes of southern Arizona: unpub. M.S. thesis, Univ. of Arizona, Tucson, 184p. Bouse, R. M., Ruiz, J., and Titley, S. R., 199Oa, ICPMS common Pb isotopic analyses of Arizona ore deposits suggest the crustal inheritance of metal ratios (abs): Geol. Soc. Amer. Abs. with Progs., v. 22, p. 56. Bouse, R. M., Ruiz, J., Titley, S. R., and Lang, J. R., 199Ob, Common Pb isotopic evidence from Laramide plutons and Phanerozoic mineralization ill Arizona for the inheritance of isotopic and metal ratios from Proterozoic basement (abs): EOS, v. 71, p. 1681. Bowring, S. A., and Karistrom, K. E., 1990, Growth, stabilization, and reactivation of Proterozoic lithosphere in the southwestern United States: Geology, v. 18, p. 1203-1206. Bradfish, L. J., 1979, Petrogenesis of the Tea Cup granodiorite, Pinal County, Arizona: unpubl. M. S. thesis, Univ. of Arizona, Tucson, 160p. 192 Burnham, C. W., 1979, Magmas and hydrothermal fluids: in Barnes, H. L., ed., Geochemistry of hydrothermal ore deposits, John Wiley and Sons, New York, p. 71-136. Burnham, C. W., and Ohmoto, H., 1980, Late stage processes of felsic magmatism: in Ishihara, S., and Takenouchi, S., eds., Granitic magmatism and related mineralization, Soc. Mining Geo!. Japan, p. 1-11. Cameron, K. L., Minz, G. J., and Kuentz, D., 1989, Southern Cordilleran basaltic andesite suite, southern Chihuahua, Mexico: A link between Tertiary continental arc and flood basalt magmatism in North America: Jour. Geophys. Res., v. 94, p. 7817-7840. Cameron, K. L, Robinson, J. V, Niemeyer, S., and Nimz, G. J., 1990, Trace-element and isotope geochemistry of deep crustal xenoliths from La Olivina, central Chihuahua, Mexico (abs): Geo!. Soc. Amer. Abs. Progs., v. 22, p. 12. Candela, P. A, 1989, Calculation of magmatic fluid contributions to porphyry-type ore systems: Predicting fluid inclusion chemistries: Geochem. Jour. (Japan), v. 23, p. 295-306. Candela, P. A, 1990, Theoretical constraints on the chemistry of the magmatic aqueous phase: in Stein, H. J., and Hannah, J. L., eds., Ore-bearing granite systems; petrogenesis and mineralizing processes: Geo!. Soc. Amer. Spec. Paper 246, p. 11-20. Candela, P. A, and Holland, H. D., 1986, A mass transfer model for copper and molybdenum in magmatic hydrothermal systems: the origin of porphyry-type ore deposits: Econ. Geo!., v. 81, p. 1-19. Cawthorn, R. G., and Brown, P. A., 1976, A model for the formation crystallization of corundum normative calc-alkaline magmas through amphibole fractionation: Jour. Geo!., v. 84, p.467- 476. Chamberlain, K. R., and Bowring, S. A, 1990, Proterozoic geochronologic and isotopic boundary in NW Arizona: Jour. Geo!., v. 98, p. 399-416. Charoy, B., 1986, The genesis of the Cornubian Batholith (South-West England): the example of the Carnmenellis pluton: Jour. Petrology, v. 27, p. 571-604. Christman, J. L., 1978, Geology, alteration, and mineralization of the Copper Basin porphyry copper deposit, Yavapai County, Arizona: unpub. M.S. thesis, Univ. of Arizona, Tucson, 78p. Clayton, R. W., 1991, Transition Zone crustal structure from extend-correlated industry seismic reflection profiles (abs): Geo!. Soc. Amer. Abs. Progs., v. 23, p. 14. Cline, J. S., and Bodnar, R. J., in press, Can economic porphyry copper mineralization be generated by a "typical" calc-alkaline melt?: Jour. Geophys. Res. Condie, K. C., 1982, Plate tectonics model for Proterozoic continental accretion in the southwestern United States: Geology, v. 10, p. 37-42. Coney, P. J., and Reynolds, S. J., 1977, Cordilleran Benioff zones: Nature, v. 270, p. 403-406. Conway and Silver, 1989, Early Proterozoic rocks (1710-1615 Ma) in central to southeastern Arizona: in Jenney, J. P., and Reynolds, S. J., eds., Geologic evolution of Arizona: Geol. Soc. Ariz. Dig., v. 17, p. 165-186. 193 Cooper, J. L., and Hart, W. K., 1990, Mantle sources in the Arizona transition zone and global mantle heterogeneity: Geology, v. 18, p. 1146-1149. Cooper, J. R., 1960, Some geologic fesatures of the Pima mining district, Pima County, Arizona: U. S. Geol. Sur. Bull. 1112-C, 103p. Cooper, J. R., 1973, Geologic map of the Twin Buttes Ouadrangle, southwest of Tucson, Arizona: U. S. Geol. Sur. Misc. Geo!. Inv. Map 1-745. Cornwall, H. R., 1982, Petrology and chemistry of igneous rocks: Ray porphyry copper district, Pinal County, Arizona: in Titley, S. R., ed., Advances in geology of the porphyry copper deposits, southwestern North America, University of Arizona Press, Tucson, p. 259-274. Creasey, S. C., 1984, The Schultze Granite" the Tea Cup Granodiorite, and the Granite Basin Porphyry: A geochemical comparison of mineralized and unmineralized stocks in southern Arizona: U. S. Geo!. Sur. Prof. Pap. 1303, 41p. Creasey, S. C., and Kistler, R., 1962, Age of some copper-bearing porphyries and other igneous rocks in southeastern Arizona: U. S. Geo!. Sur. Prof. Pap. 450-0, p. 01-05. Damon, P. E., 1970, New K-Ar dates for the southern Basin and Range Province: Ann. Prog. Rpt., Research Division, U. S. Atomic Energy Comm., p. 38. Damon, P. E., and Mauger, R. L., 1966, Epierogeny-orogeny viewed from the Basin and Range Province: Soc. Metal!. Engs. Trans., v. 23?, p. 99-112. Damon, P. E., and others, 1964, Correlation and chronology of the ore deposits and volcanic rocks: Tucson, Univ. of Arizona, U. S. Atomic Energy Comm. Ann. Rpt, no. COO-689-42. Damon, P. E., and others, 1970, Correlation and chronology of the ore deposits and volcanic rocks: Tucson, Univ. of Arizona, U. S. Atomic Energy Comm. Ann. Rpt., no. CQQ-689-130. DePaolo, D. J., 1981a, Neodymium isotopes in the Colorado Front Range and crust-mantle evolution in the Proterozoic: Nature, v. 291, p. 193-196. r DePaolo, D. J., 1981b, Trace element and isotopic effects of combined wa1lrock assimilation and fractional crystallization: Earth Planet. Sci. Letts., v. 53, p. 189-202. Drake, M. J., and Weill, D. F., 1975, Partition of Sr, Ba, Ca, Y, Etf+ , EtP+ , and other REE between plagioclase feldspar and magmatic liquid: an experimental study: Geochim. Cosmochim. Acta, v. 39, p. 689-712. Drewes, H., 1981, Tectonics of southeastern Arizona: U. S. Geo!. Sur. Prof. Pap. 1144,93p. Engebretsen, D. C., Cox, A., and Gordon, R. G., 1985, Relative motions between oceanic and continental plates in the Pacific basin: Geo!. Soc. Amer. Spec. Paper 206, 59p. Esperanca, S., Carlson, R. W., and Shirey, S. B., 1988, Lower crustal evolution under central Arizona: Sr, Nd and Pb isotopic and geochemical evidence from the mafic xenoliths of Camp Creek: Earth Planet. Sci. Letts., v. 90, p. 26-40. Farmer, G. L., 1988, Isotope geochemistry of Mesozoic and Tertiary igneous rocks in the western United States and implications for the structure and composition of the deep continental lithosphere: in Ernst, W. G., ed., Metamorphism and crustal evolution, western 194 conterminous United States; Rubey Volume 7: Englewood Cliffs, New Jersey, Prentice Hall, p. 87-109. Farmer, G. L., and DePaolo, D. J., 1983, Origin of Mesozoic and Tertiary granite in the western United States and implications for pre-Mesozoic crustal structure 1. Nd and Sr isotopic studies in the geocline of the northern Great Basin: Jour. Geophys. Res., v. 88, p. 3379- 3401. Farmer, G. L., and DePaolo, D. J., 1984, Origin of Mesozoic and Tertiary granite in the western United States and implications for pre-Mesozoic crustal structure 2. Nd and Sr isotopic studies of unmineralized and Cu- and Mo-mineralized granite in the Precambrian craton: Jour. Geophys. Res., v. 89, p. 10141-10160. Farmer, G. L., and DePaolo, D. J., 1987, Nd and Sr isotope study of hydrothermally altered granite at San Manuel, Arizona: Implications for element migration paths during the formation of porphyry copper ore deposits: Econ. Geo!., v. 82, p. 1142-1151. Farmer, G. L., Perry, F. V., Semkin, S., Crowe, B., Curtis, D., and DePaolo, D. J., 1989, Isotopic evidence on the structure and origin of subcontinental lithospheric mantle in southern Nevada: Jour. Geophys. Res., v. 94 p. 7885-7898. Feiss, P. G., 1978, Magmatic sources of copper in porphyry copper deposits: Econ. Geo!., v. 73, p. 397-404. Flynn, R. T., and Burnham, C. W., 1978, An experimental determination of rare earth partitioning coefficients between a chloride containing vapor phase and silicate melts: Geochim. Cosmochim. Acta, v. 42, p. 685-701. Gerla, P. J., 1983, Structure and hydrothermal alteration of the Diamond Joe stock, Mohave County, Arizona: unpub. Ph.D. diss., Univ. of Arizona, Tucson, 120p. Gilluly, J., 1956, General geology of central Cochise County Arizona: U. S. Geo!. Sur. Prof. Pap. 281,169p. Gilmour, P., 1982, Grades and tonnages of porphyry copper deposits: in Titley, S. R, cd., Advances in geology of the porphyry copper deposits, southwestern North America: Univ. of Arizona Press, Tucson, p. 7-36. Gromet, L. P., and Silver, L. T., 1983, Rare earth element distributions among minerals in a granodiorite and their petrogenetic implications: Geochim. Cosmochim. Acta, v. 47, p. 925- 940. Guthrie, J. 0., and Moore, D. G., 1978, The geology of the Copper Creek area, Bunker Hill mining district, Galiuro Mountains, Arizona: Ariz. Geo!. Soc. Dig., v. 11, p. 25-31. Hanchar, J. M., Miller, C. F., and Staude, J. M. G., 1990, Lower crustal xenoliths in Tertiary dikes, Old Woman mountains area, southeastern California: I. Petrology (abs): Geo!. Soc. Amer. Abs. Progs., v. 22, p. 28. Haxel, G. B., Tosdal, R M., May, D. J., and Wright, J. E., 1984, Latest Cretaceous and early Tertiary orogenesis in south-central Arizona: Thrust faulting, regional metamorphism, and granitc plutonism: Geo!. Soc. Amer. Bull., v. 95, p. 631-653. 195 Hess, N. J., 1986, Petrology and crystal chemistry of the Ruby Star granodiorite, Pima County, Arizona: unpub. M.S. thesis, Univ. of Arizona, Tucson, 71p. Hildreth, W., and Moorbath, S., 1988, Crustal contributions to arc magmatism in the Andes of Central Chile: Contrib. Mineral. Petrol., v. 98, p. 455-489. Holland, H. D., 1972, Granites, solutions, and base metal deposits: Econ. Geol., v. 67, p. 281-301. Hon, R., and Weill, D. F., 1990, Heat balance of basaltic intrusion versus granitic fusion in the lower crust (abs): EOS, v. 63, p. 470. Humphris, S. E., 1984, The mobility of the rare earth elements in the crust: in Henderson, P., ed., Rare earth element geochemistry: Elsevier Science Publishers, Amsterdam, p. 317-342. Huppert, H. E., and Sparks, S. J., 1988, The generation of granitic magmas by intrusion of basalt into continental crust: Jour. Petrol., v. 29, p. 599-624. Jacobsen, S. B., and Wasserburg, G. J., 1984, Sm-Nd isotopic evolution of chondrites and achondrites, II: Earth Planet. Sci. Letts., v. 67, p. 137-150. Jansen, L. J., 1982, Stratigraphy and structure of the Mission copper deposit, Pima mining district, Pima County, Arizona: in Titley, S. R, ed., Advances in geology of the porphyry copper deposits, southwestern North America: Univ. of Arizona Press, Tucson, p. 467-474. Jenner, G. A., Longerich, H. P., Jackson, S. E., and Fryer, B. J., 1990, ICP-MS -- a powerful tool for high-precision trace-element analysis in Earth sciences: Evidence from analysis of selected U.S.G.S. reference samples: Chem. Geol., v. 83, p. 133-148. Johnson, R A., and Smithson, S. B., 1990, Seismic constraints on lower crustal structure and composition in the southwestern U.S. (abs): Geol. Soc. Amer. Abs. Progs., v. 22, p. 33. Johnston, W. P., and Lowell, J. D., 1961, Geology and origin of mineralized breccia pipes in Copper Basin, Arizona: Econ. Geol., v. 56, p. 916-940. Jones, B. K., and LeVeille, R A., 1989, Application of metal zoning relationships and metal ratios to gold exploration in porphyry systems: 95th Annual Northwest Mining Association Meeting preprint, 38p. Karlstrom, K. E., and Bowring, S. A., 1988, Early Proterozoic assembly of tectonostratigraphic terranes in southwestern North America: Jour. Geol., v. 96, p. 561-576. Keith, S. B., 1977, Compilation of radiometric age dates for Arizona: Ariz. Bur. Geol. Mineral Tech. Open File Rpt 77-1a, 187p. Keith, S. B., 1986, A contribution to the geology and tectonics of the Ray-Superior region, Pinal County, Arizona: Ariz. Geol. Soc. Dig., v. 16, p. 392-407. Kelly, J. L., 1977, Geology of the Twin Buttes copper deposit, Pima County, Arizona: SME-AIME Trans., v. 262, p. 110-116. Kempton, P. D., Harmon, R S., Hawkesworth, C. J., and Moorbath, S., 1990, Petrology and geochemistry of lower crustal granulites from the Geronimo Volcanic Field, southeastern Arizona: Geochim. Cosmochim. Acta, v. 54, p. 3401-3426. 196 Kesler, S. E., 1973, Copper, molybdenum, and gold abundances in porphyry copper deposits: Econ. Geol., v. 68, p. 106·112. Kesler, S. E., Issigonis, J. M., Brownlow, A H., Damon, P. E., Moore, W. J., Northcote, K. E., and Preto, V. A, 1975, Geochemistry of biotite from mineralized and barren intrusive systems: Econ. Geo!., v. 70, p. 643-659. Kirkham, R. V., and Sinclair, W. D., 1988, Comb quartz layers in felsic intrusions and their relationship to porphyry deposits: in Taylor, R. P., and Strong, D. F., cds., Recent advances in the geology of granite·related mineral deposits: Can. Inst. Mining and Metal!., Spec. Vo!. 39, p. 50-71. Koski, R. A, and Cook, D. S,' 1982, Geology of the Christmas porphyry copper deposit: Gila County, Arizona: in 'fitley, S. R., cd., Advan('.cs in Geology of the Porphyry Copper Deposits, southwestern North America, Univ. of Arizona Press, Tucson, p. 353-374. Kuhn, T. H., 1941, Pipe deposits of the Copper Creek area, Arizona: Econ. Geo!., v. 36, p. 512-538. Lang, J. R., and Eastoe, C. J., 1988, Relationships between a porphyry CuoMo deposit, base and precious metal veins, and Laramide intrusions, Mineral Park, Arizona: Econ. Geo!., v. 83, p. 551-567. Lang, J. R., Titley, S. R., Patchett, P. J., Ruiz, J., and Bouse, R. M., 1990, Sources of Mesozoic granitoids in Arizona from radiogenic isotope chemistry (abs): EGS, v. 71, p. 1681. Langton, J. M., and Williams, S. A, 1982, Structural, petrological and mineralogical controls for the Dos Pobres orebody, Lone Star mining district, Graham County, Arizona: in Titley, S. R., editor, Advances in Geology of the Porphyry Copper Deposits, Southwestern North America, University of Arizona Press, Tucson, p. 335·352. Le Bel, L. M., 1985, Mineralization in the Arequipa segment: the porphyry-Cu deposit of Cerro Verde/Santa Rosa: in Pitcher, W. S., Atherton, M. P., Cobbing, E. J., and Beckinsale, R. D., eds., Magmatism at a Plate Edge: The Peruvian Andes: Halsted Press, New York, p. 250-260. Livingston, D. E., Damon, P. E., Mauger, R. L., Bennett, R., and Laughlin, A W., 1967, Argon 40 in oogenetic feldspar-mica mineral assemblages: Jour. Geophys. Res., v. 72, p. 1361·1375. London, D., Morgan, G. B., and Hervig, R. L., 1987, Differentiation of peraluminous, volatile-rich granites: An experimental study of Macusani glass (abs): Geo!. Soc. Amer. Abs. Progs., v. 19, p. 749. Longerich, H. P., Jenner, G. A, Fryer, B. J., and Jackson, S. E., 1990, Inductively coupled plasma mass spectrometric analysis of geological samples: A critical evaluation based on case studies: Chem. Geo!., v. 83, p. 105-118. Manchester, J., Smith, D., and Tyner, G. N., 1990, Chino Valley xenoliths: Lower crust and upper mantle below the Colorado Plateau Transition Zone (abs): Geo!. Soc. Amer. Abs. Progs., v. 22, p. 63. Marvin, R. F., and Cole, J. L., 1978, Radiometric ages: Compilation A: IS'Jchron/West, v. 22, p. 3- 14. 197 Marvin, R. F., Stern, T. W., Creasey, S. C., and Mehnert, H. H., 1973, Radiometric ages of igneous rocks from Pima, Santa Cruz, and Cochise counties, southeastern Arizona: U. S. GenJ. Sur. Bull. 1379, 27p. Mason, D. R., 1978, Compositional variations in ferro magnesian minerals from porphyry copper generating and barren intrusions of the Western Highlands, Papua New Guinea: Econ. Geol., v. 73, p. 878-890. Mason, D. R, and Feiss, P. G., 1979, On the relationship between whole rock chemistry and porphyry copper mineralization: Econ. Geol., v. 74, p. 1506-1510. Mason, D. R., and MacDonald, J. A, 1978, Intrusive rocks and porphyry copper occurrences of the Papua New Guinea - Solomon Islands region: A reconnaissance study: Econ. Geol., v. 73, p.857-877. McCarthy, J., Okaya, D. A, and Goodwin, E. B., 1990, Geophysical character of the middle and lower crust in the southwestern U.S.: Results from seismic profiling (abs): Geol. Soc. Amer. Abs. Progs., v. 22, p. 65. McCurry, W. G., 1971, Mineralogy and paragenesis of the ores, Christmas mine, Gila County, Arizona: un pub M. S. thesis, Arizona State Univ., Tempe. McDowell, F. W., 1971, K-Ar ages of igneous rocks from the western United States: Isochron/West, v. 2, p. 1-17. McKee, E. H., and Koski, R. A, 1981, K-Ar ages for igneous rocks and vein minerals from the Christmas Mine area: Isochron/West, v. 32, p. 7-12. Menzies, M. A, 1989, Cratonic, circum cratonic and oceanic mantle domains beneath the western United States: Jour. Geophys. Res., v.94, p. 7899-7915. Metz, R. A, and Rose, A W., 1966, Geology of the Ray copper deposit, Ray, Arizona: in Titley, S. R., and Hicks, C. L., eds., Geology of the porphyry copper deposits, southwestern North America: Tucson, Univ. Arizona Press, p. 176-188. Miller, C. F., and Mittlefehldt, D. W., 1982, Depletion of light rare-earth elements in felsic magmas: Geology, v. 10, p. 129-133. Miller, C. F., and Barton, M. D., 1990, Phanerozoic plutonism in the Cordilleran interior, U.SA.: in Anderson, J. L., ed., The nature and origin of Cordilleran magmatism: Geol. Soc. Amer. Memoir 174, p. 213-231. Miller, C. F., Wooden, J. L., Bennett, V. C., Wright, J. E., Solomon, G. C., and Hurst, R. W., 1990, Petrogenesis of the composite peraluminous-met aluminous Old Woman-Piute batholith, southeastern Clalifornia: Isotopic constraints: in Anderson, J. L., ed., The nature and origin of Cordilleran magmatism: Geol. Soc. Amer. Memoir 174, p. 99-109. Moorbath, S., Hurley, P. M., and Fairbairn, H. W., 1967, Evidence for the origin and age of some mineralized Laramide intrusives in the southwestern United States from strontium isotope and rubidium-strontium measurements: Econ. Geol., v. 66, p. 228-236. Nagasawa, H., 1970, Rare earth concentrations in zircons and apatites and their host dacites and granites: Earth Planet. Sci. Letts., v. 9, p. 359-364. 198 Nagasawa, H., and Schnetzler, C. C., 1971, Partitioning of rare earth, alkali and alkaline earth elements between phenocrysts and acidic igneous magma: Geochim. Cosmochim. Acta, v. 35, p. 953-968. Nakano, T., and Urabe, T., 1989, Calculated compositions of fluids released from a crystallizing granitic melt: Importance of pressure on the genesis of ore-forming fluid: Geochem. Jour. (Japan), v. 23, p. 307-320. Naney, M. T., 1983, Phase equilibria of rock-forming ferromagnesian silicates in granitic systems: Amer. Jour. Sci., v. 283, p. 993-1033. Nash, W. P., and Crecraft, H. R., 1985, Partition coefficients for trace elements in silicic magmas: Geochim. Cosmochim. Acta, v. 49, O. 2309-2322. Nealey, L. D., Unruh, D. M., Knight, R. J., and King, B. W., 1990, Geochemistry of deep crustal xenoliths from the southern Colorado Plateau, northern Arizona (abs): Geol. Soc. Amer. Abs. Progs., v. 22, p. 72. Nelson, B. K., and DePaolo, D. J., 1985, 1,700-Myr greenstone volcanic successions in southwestern North Americaa and isotopic evolution of Proterozoic mantle: Nature, v. 312, p. 143-146. Newell, R. A, 1974, Exploration geology and geochemistry of the Tombstone-Charleston area, Cochise County, Arizona: unpub. Ph.D dissert., Stanford Univ., 205p. Patchett, P. J., 1980, Thermal effects of basalt on continental crust and crustal contamination of magmas: Nature, v. 283, p. 559-561. Patchett, P. J., and Ruiz, J., 1987, Nd isotopic ages of crust formation and metamorphism in the Precambrian of eastern and southern Mexico: Contrib. Mineral. Petrol., v. 96, p. 523-528. Peacock, M. A, 1931, Classification of igneous rock series: Jour. Geol., v. 39, p. 54-67. Peterson, N. P., and Swanson, R. W., 1956, Geology of the Christmas copper mine, Gila County, Arizona: U. S. Geol. Sur. Bull. 1027-H, p. 351-373. Phillips, C. H., Gambell, N. A, and Fountain, D. S., 1974, Hydrothermal alteration, mineralization, and zoning in the Ray deposit: Econ. Geol., v. 69, p. 1237-1250. Pimentel, M. M., and Charnley, N., 1991, Intracrustal REE fractionation and implications for Sm-Nd model age calculations in late stage granitic rocks: An example from central Brazil: Isotope Geoscience, v. 86, p. 123-138. Ransome, F. L., 1919, The copper deposits of Ray and Miami, Arizona: U. S. Geol. Sur. Prof. Pap. 115,192p. Rehrig, W. A, and Heidrick, T. L., 1976, Regional tectonic stress during the Laramide and late Tertiary intrusive periods, Basin and Range province, Arizona: Ariz. Geol. Soc. Dig., v. 10. p.205-228. Reynolds, S. J., Florence, F. P., Currier, D. A, Anderson, A V., Trapp, R. A, and Keith, S. B., 1985, Compilation of K-Ar age determinations: Ariz. Bur. Geol. Mineral Tech. Open File Rpt 85-8, 320p. 199 Roberts, S. J., and Ruiz, J., 1989, Geochemistry of exposed granulite facies terrains and lower crustal xenoliths in Mexico: Jour. Geophys. Res., v. 94, p. 7%1-7974. Robinson, R. F., and Cook, A., 1966, The Safford copper deposit, Lone Star mining district, Graham County, Arizona: in Titley, S. R, and Hicks, C. L., eds., Geology of the porphyry copper deposits, southwestern North America: Univ. of Arizona Press, Tucson, p. 251-266. Rose, A. W., and Cook, D. R, 1966, Radioactive dates of porphyry copper deposits in western United States: Geol. Soc. Amer. Spec. Pap. 87, p. 141-142. Ruiz, J., Patchett, P. J., and Arculus, R J., 1988a, Nd - Sr isotope composition of lower crustal xenoliths - evidence for the origin of mid-Tertiary felsic volcanics in Mexico: Contrib. Mineral. Petrol., v. 99, p. 36-43. Ruiz, J., Patchett, P. J., and Ortega-Gutierrez, F., 1988b, Proterozoic and Phanerozoic basement terranes of Mexico from Nd isotopic studies: Geol. Soc. Amer. Bull., v. 100, p. 274-281. Shafiqullah, M., and Langlois, J. D., 1978, The Pima mining district, Arizona -- a geochronologic update: New Mex. Geol. Soc., 29th Field Conference, Land of Cochise, p. 321-327. Shafiqullah, M., Damon, P. E., Lynch, D. J., Reynolds, S. J., Rehrig, W. A., and Raymond, R. H., 1980, K-Ar geochronology and geologic history of southwestern Arizona and adjacent areas: Ariz. Geol. Soc. Dig., v. 12, p. 201-260. Sheppard, S. M. F., Neilsen, R. L., and Taylor, H. P., Jr., 1971, Hydrogen and oxygen isotope ratios in minerals form porphyry copper depsoits: Econ. Geol., v. 66, p. 515-542. Shoemaker, E. M., Squires, R L., and Abrams, M. J., 1978, Bright Angle and Mesa Butte fault systems of northern Arizona: Geol. Soc. Amer. Memoir 152, p. 341-368. Simmons, E. C., and Hedge, C. E., 1978, Minor-element geochemistry and Sr-isotopes of Tertiary stocks, Colorado mineral belt: Contrib. Mineral. PetroL, v. 67, p. 379-396. Stein, H. J., and Crock, J. G., 1990, Late Cretaceous-Tertiary magmatism in the Colorado Mineral Belt; rare earth clement and samarium-neodymium isotopic studies: in Anderson, J. L., ed., The nature and origin of Cordilleran magmatism: Geo!. Soc. Amer. Memoir 174, p. 195- 223. Strekeisen, A. L., 1976, To each plutonic rock its proper name: Earth Sci. Rev., v. 12, p. 1-33. Takahashi, E., 1986, Genesis of calc-alkali andesite magma in a hydrous mantle-crust bouildary: Petrology of lherzolite xenoliths from the Ichinomegata crater, Oga Peninsula, northeast Japan, Part II: Jour. Volc. Geotherm. Res., v. 29, p. 355-395. Taylor, S. R, and McClennan, S. M., 1985, The continental crust: its composition and evolution: Blackwell Scientific, London, 312p. Titley, S. R., 1981, Geologic and geotectonic setting of porphyry copper deposits in the southern Cordillera: Ariz. Geo!. Soc. Dig., v. 14, p. 79-97. Titley, S. R, 1982a, Some features of tectonic history and ore genesis in the Pima mining district, Pima County, Arizona: in Titley, S. R, ed., Advances in geology of the porphyry copper deposits, southwestern North America: Univ. of Arizona Press, Tucson, p. 387-406. 200 Titley, S. R., 1982b, The style and progress of minera1ization and alteration in porphyry copper systems: American Southwest: in Titley, S. R., ed., Advances in geology of the porphyry copper deposits, southwestern North America: Univ. of Arizona Press, Tucson, p. 93-116. Titley, S. R., 1987, The crustal heritage of silver and gold ratios in Arizona ores: Geol. Soc. Amer. Bull., v. 99, p. 814-826. Titley, S. R., 1989, Contrasting characteristics of precious-metal-bearing porphyry systems: 95th Annual Northwest Mining Association Meeting preprint, 11p. Titley, S. R., 1991, Correspondence of ores of silver and gold with basement terranes in the American southwest: Mineral. Deposita, v. 26, p. 66-71. Titley, S. R., and Beane, R. E., 1981, Porphyry copper deposits, Part I, geologic settings, petrology, and tectogenesis: Econ. Geol. 75th Anniv. Vol., p.214-235. Titley, S. R., and Anthony, E. Y., 1989, Laramide mineral deposits in Arizona: in Jenney, J. P., and Reynolds, S. J., eds., Geologic evolution of Arizona: Geol. Soc. Ariz. Dig., v. 17, p. 485-514. Titley, S. R., Thompson, R. C., Haynes, F. M., Manske, S. L., Robinson, L. C., and White, J. L., 1986, Evolution of fractures and alteration in the Sierrita-Esperanza hydrothermal system, Pima County, Arizona: Econ. Geol., v. 81, p. 343-370. Trapp, R. A., 1987, Geochemistry of the Laramide igneous suite of the Santa Rita and Empire mountains, southeastern Arizona: unpub. M.S. thesis, Univ. of Arizona, Tucson, 118p. Vielzeuf, D., Clemens, J. D., Pin, C., and Moinet, E., 1990, Granites, granulites and crustal differentiation: in Vielzeuf, D., and Vidal, Ph., eds., "Granulites and crustal evolution: Proceedings of the NATO Advanced Research Workshop on Petrology and Geochemistry of Granulites, Clermont-Ferrand, France, Sept. 5-9, 1988: Kluwer Academic Publishers, Dordrecht, Netherlands, NATO ASI Series C, vol. 311, p. 59-85. . Walker, V. A., 1979, Relationships among several breccia pipes and a lead-silver vein in the Copper Creek mining district, Pinal County, Arizona: unpub. M.S. thesis, Univ. of Arizona, Tucson, 163p. Warren, R. G., Kudo, A. M., and Keil, K., 1978, Geochemistry of lithic and single-crystal inclusions in basalt and a characterization of the upper mantle-lower crust in the Engle Basin, Rio Grande Rift, New Mexico: in Riecker, R. E., ed., Rio Grande Rift: Tectonics and Magmatism: Amer. Geophys. Union, Lithocrafters, Chelsea, Michigan, p. 393-415. West, R. J., and Aiken, D. M., 1982, Geology of the Sierrita-Esperanza deposit, Pima mining district, Pima County, Arizona: in Titley, S. R., ed., Advances ill geology of the porphyry copper deposits, southwestern North America: Univ. of Arizona Press, Tucson, p. 433-465. Wilkinson, W. H., Vega, L. A., and Titley, S. R., 1982, Geology and ore deposits at Mineral Park: Mohave County, Arizona: in Titley, S. R., cd., Advances in geology of the porphyry copper deposits: southwestern North America: Tucson, Univ. of Arizona Press, p. 523-542. Willden, R., 1964, Geology of the Christmas quadrangle, Gila and Pinal Counties, Arizona: U. S. Geol. Sur. Bull., 1161-E, 64p. Wilson, M., 1989, Igneous petrogenesis: A global tectonic approach: Unwin Hyman, London, 466p. 201 Wooden, J. L., Stacey, J. S., Howard, K. A., Doe, B. R., and Miller, D. M., 1988, Lead isotopic evidence for the formation of Proterozoic crust in the southwestern United States: in Ernst, W. G., ed., Metamorphism and crustal evolution, western conterminous United States; Rubey Volume 7: Englewood Cliffs, New Jersey, Prentice-Hall, p. 68-86. Woodell, J. L., and DeWitt, E., in press,Pb isotopic evidence for the boundary between the early Proterozoic Mojave and Central Arizona crustal provinces in western Arizona Wooden, J. L., and Miller, D. M., in press, Chronologic and isotopic framework for Early Proterozoic crustal evolution in the eastern Mojave Desert region, SE California Wooden, J. L., and Tosdal, R. M., 1990, Common Pb isotopl': evidence for sources of Mesozoic and Tertiary magmatism in SE Calif. and SW Ariz. (abs): Geo!. Soc. Amer. Abs. Progs., vo!. 22, p.95. Wyllie, P. J., 1981, Magma sources in cordilleran settings: Ariz. Geo!. Soc. Digest, v. 14, p. 39-48. Yarter, W. V., 1981, Geology, geochemistry, alteration, and mass transfer in the Sol prospect, a sub economic porphyry copper-molybdenum deposit, Safford district, Graham County, Arizona: unpub. M. S. thesis, Univ. of Arizona, Tucson, 136p. Yurimoto, H., Duke, E. F., Papike, J. J., and Shearer, C. K., 1990, Are discontinuous chondrite normalized REE patterns in pegmatitic granite systems the result of monazite fractionation?: Geochim. Cosmochim. Acta, v. 54, p. 2141-2145. Zhitian, W., and Kezhang, Qin, 1989, REE geochemical character of porphyry copper molybdenum multimetal metallogenic series and its application to distinguishing ore-bearing quality of porphyries in Manzhouli-Xinbaerhuyouqi area of Inner Mongolia: in Progress in Geosciences of China (1985-1988) -- Papers to the 28th IGC, Washington, USA, p. 125-128. Zindler, A., and Hart, S., 1986, Chemical geodynamics: Ann. Rev. Earth Planet. Sci., v. 14, p. 493- 571.