Statistical Study of Selected Trace 

Elements with Reference to Geology and 

Genesis of the Carlin Gold Deposit, 

Nevada 

By MICHAEL HARRIS and ARTHUR S. RADTKE 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 960 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1976 
UNITED STATES DEPARTMENT OF THE INTERIOR 

THOMAS S. KLEPPE, Secretary 

GEOLOGICAL SURVEY 

V. E. l\fcKelvey, Director 

Library of Congress Cataloging in Publication Data 

Radtke, ArthurS. 1936-

Statistical study of selected trace elements with reference to geology and genesis of the Carlin gold deposit, Nevada. 

(Geological Survey Professional Paper 960) 

Bibliography: p. 20-21. 

Supt. of Docs. no.: I 19.16:960. 

1. Trace elements-Statistical methods. 2. Geochemistry-Nevada-Carlin. 3. Gold ores-Nevada-Carlin. I. Harris, 

Michael, 1949- joint author. II. Title: Statistical study of selected trace elements ... III. Series: United States 

Geological Survey Professional Paper 960. 

QE516.T85R3 553'.41'097316 76-608006 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 

Stock Number 024-001-02771-2 
CONTENTS 

Page 

Abstract------------------------------------------------------------------------------ 1 

Introduction -------------------------------------------------------------------------- 2 

Acknovvledgr.nents ---------------------------------------------------------------- 2 

(}eologic setting ---------------------------------------------------------------------- 3 <1enesis of the ores _ _ ____ _ _ _ _ _ ___ _ _ _ _ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ __ _ _ _ _ __ _ _ __ _ _ _ _ _ _ ___ _ _ _ _ _ _ _ 3 

(}eology of the ore bodies -------------------------------------------------------------- 7 

Statistical analysis of gold, mercury, arsenic, and antimony------------------------------ 8 

Statistical analysis of gold, barium, copper, molybdenum, lead, and zin~ ------------------ 16 

Statistical analysis of gold, boron, tellurium, selenium, and tungsten -------------------- 18 

References cited ---------------------------------------------------------------------- 20 

ILLUSTRATIONS 

Page 

FIGURE 1. Index map of the Carlin gold deposit_______________________________________________________________________________ 3 

TABLE 

2. Simplified geologic map of the Carlin gold deposit_ _________________________________________________ ----------------- 4 

3. Diagram shovving mineralization paragenesis at the Carlin gold deposit --------------------------------------------- 6 

4. Direct scatter plots of gold, mercury, arsenic, and antimony in unoxidized Carlin ores--------------------------------- ~0 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

TABLES 

Page 

Data on elements studied and analytical procedures----------------------------------------------------------------- 2 

Abundance of gold, mercury, arsenic, and antimony in fresh limestones and unmineralized carbonate host rocks and unoxidized gold ores at the Carlin deposit --------------------------------------------------------------------------- 8 

Mean values and standard deviations for gold, mercury, arsenic, and antimony in the West, Main, and East ore bodies at the 

Carlin gold deposit ------------------------------------------------------------------------------------------- 11 

Linear correlation coefficients between gold, mercury, arsenic, and antimony for the West, Main, and East ore bodies at 

the Carlin gold deposit --------------------------------------------------------~------------------------------ 11 

Abundance of gold, barium, copper, molybdenum, lead, and zinc in fresh limestones and unmineralized carbonate host 

rocks and unoxidized gold ores at the Carlin deposit ----------------------------------------------------------- 17 

Mean values and standard deviations for gold, barium, copper, molybdenum, lead, and zinc in the West, Main, and East ore 

bodies at the Carlin gold deposit------------------------------------------------------------------------------- 17 

Linear correlation coefficients betvveen gold, barium, copper, molybdenum, lead, and zinc for the West, Main, and East ore bodies at the Carlin gold deposit_ _____________________________________________________________ ----------------- 17 

Abundance of gold, boron, tellurium, selenium, and tungsten in fresh limestones and unmineralized carbonate host rocks 

and unoxidized gold ores at the Carlin deposit ----------------------------------------------------------------- 19 

Mean values and standard deviations for gold, boron, tellurium, selenium, and tungsten in the West, Main, and E~st ore bodies at the Carlin gold deposit_ _____________________________________________________________ ----------------- 19 

Linear correlation coefficients betvveen gold, boron, tellurium, selenium, and tungsten for the West, Main, and East ore bodies at the Carlin gold deposit_ _____________________________________________________________ -------------,---- 19 

III 
STATISTICAL STUDY OF SELECTED TRACE 

ELEMENTS WITH REFERENCE TO GEOLOGY AND 

GENESIS OF THE CARLIN GOLD DEPOSIT, NEVADA 

By MICHAEL HARRIS and ARTHUR S. RADTKE 

ABSTRACT 

Linear regression and discriminant analyses techniques were I 

applied to gold, mercury, arsenic, antimony, barium, copper, 

molybdenum, lead, zinc, boron, tellurium, selenium, and tungsten 

analyses from drill holes into unoxidized gold ore at the Carlin gold 

mine near Carlin, Nev. The statistical treatments employed were 

used to judge proposed hypotheses on the origin and geochemical 

paragenesis of this disseminated gold deposit. 

The West, Main, and East ore bodies of the Carlin deposit are in the 

upper 265+ m (869ft) of the Silurian and Early Devonian Roberts 

Mountains Formation in the northeast corner of the Lynn window 

near the crest of a large northwest-plunging anticline. The intensely 

deformed carbonate host rocks are in an area containing many 

intersecting high-angle faults and breccia zones that were the 

principal channelways for the ore solutions. The major faulting and 

igneous activity in the mine area took place before the ore formed. 

The ore solutions dissolved calcite out of the limestone host rock and 

introduced silica, pyrite, gold, and various other elements. The initial 

calcite removal created permeable sections that were to be the more 

receptive sites for ore deposition. Most of the gold and mercury 

precipitated during this phase is either associated with organic 

materials or occurs together with arsenic and antimony as coatings on 

pyrite grains. A subsequent mineralization (possibly. a later stage of 

the same mineralization) precipitated arsenic, antimony, and 

mercury sulfides followed by the deposition of copper, lead, zinc, and 

molybdenum sulfides and an overlapping formation of barite veins. 

The two sulfide stages and the barite veins were deposited 

independently of the gold. Geologic relations and statistical comparisons showed that the barite veins were formed after the gold 

deposition and are either associated with arsenic and (or) antimony 

sulfides, base-metal sulfides, or have no associated sulfides. Many 

analyses of barite veins performed to date have shown no detectable 

amounts of gold. 

The linear correlation coefficients between element pairs and suites 

may or may not reflect the direct cause and effect relations of the 

mineralization sequence since it is most probable that many 

parameters controlled their precipitation. However, most of the 

correlations found agreed with geological observations, and some 

correlations revealed subtle geochemical relations that had not been 

previously recognized. The gold, mercury, arsenic, antimony suite of 

metals in the West ore body conformed quite well to the proposed 

linear model with an almost 80 percent reduction in variance and 

linear correlation coefficients as high as 0.87. We believe that the 

West ore body most closely approximates original conditions of the 

earliest mineralization phase. This opinion is substantiated by the 

scarcity oflate arsenic, antimony, and mercury sulfides, by the lower 

organic carbon content, and by the simpler structural setting of this 

ore body. 

The distribution and interrelation of gold, mercury, arsenic, and 

antimony between and in the three ore bodies were compared by 

stepwise discriminant analyses. The results of these tests consistently 

showed the West ore body to be significantly different from the other 

two. The mean values in the Main ore body tended to be much more 

similar to the West ore body than to the East. The polarity of the 

element values in the West ore body from the other areas is in direct 

accord with the proposed mineral paragenesis model in which the late 

mercury, arsenic, and antimony sulfide mineralization occurred only 

in the vicinity of the Main and East ore bodies. 

Gold and mercury values showed high correlations in all of the 

areas tested. These correlations support the hypotheses that (1) gold 

and mercury were both transported in the same q.re solution and were 

contemporaneously precipitated in response to similar influences, and 

(2) more than 90 percent of the investigated occurrences of both 

elements are either associated with various organic materials or occur 

together on the surfaces of pyrite grains. 

Statistical analysis of a gold, barium, copper, molybdenum, lead, 

zinc suite in the West ore body gave results consistent with the 

proposed paragenetic model. The highest correlations were between 

the base metals, followed roughly by these elements to barium, and 

finally very low or not significant correlations of gold to barium and to 

the base metals. Gold was found to be negatively correlated to barium 

over the entire deposit; this relation reflects their paragenetic separation. Discriminant analysis techniques employed for this suite reconfirmed that statistically meaningful geochemical differences exist 

between the three ore bodies. Mean values in the Main ore body were 

similar to the mean values in its neighbor bodies, whereas the mean 

values of the two peripheral areas were fairly polarized toward their 

own means. 

Linear regression analyses of gold with the independent variables 

boron, tellurium, selenium, tungsten suite show that data for these 

elements fit a linear model poorly. The only significant correlation 

found was between gold and tellurium; this correlation is strongest in 

the East ore body and becomes progressively weaker through the 

Main and West ore bodies. The mode of tellurium occurrence has not 

been firmly established, but tellurium and possibly selenium could be 

present in hydrothermal pyrite or could coat pyrite grains together 

with gold, mercury, arsenic, and antimony. Discriminant analyses of 

this suite again showed the West ore body to be significantly different 

from the other two. 

There are still a multitude of unanswered questions concerning the 

genesis of the Carlin deposit. The significant standard deviations 

found make it somewhat hazardO\,l.S to draw exact conclusions from the 

statistical findings alone. However, the statistical methods employed 

were very useful in establishing guidelines to interpret data and were 

also valuable in lending support to theories on the ore genesis. 

1 
2 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

INTRODUCTION 

During the course of the geologic and geochemical 

study of the Carlin gold deposit, which began in 1968, a 

large amount of chemical data has been gathered on the 

host rocks and gold ores. Although most of these data 

were summarized in a paper by Radtke, Heropoulos, 

Fabbi, Scheiner, and Essington (1972), none of the data 

had been treated statistically. This paper presents the 

results of a statistical study made by Harris (1974), of 

certain minor elements in the unoxidized gold ores, 

together with basic geologic, mineralogic, and geochemical information provided by Radtke. Statistical data 

are applied to evaluate certain aspects of the chemical 

model of the Carlin deposit. Only analyses of samples of 

primary unoxidized ore were used, as it is likely that 

highly variable supergene oxidation processes would 

produce complicated elemental distribution patterns 

different from those produced by the original hydrothermal conditions. 

Standard stepwise regression analyses, incorporating 

computer treatments shown in Dixon (1964), were used 

to determine correlations between the important elements and the dependence of the gold content on the 

presence of these other elements. Linear correlations 

were emphasized in order to establish direct correspondences between the elements involved. 

Ahrens (1954), Lepeltier (1969), and Miesch (1967) 

gave reasons for treating geochemical data by using the 

lognormal equivalents of the numerical values found by 

analysis. We decided against using this approach for 

two main reasons: (1) Many of the analyzed values for 

some elements were reported as zero, so that by definition no log value could be assigned. We considered adding a constant, such as + 1, to all the values, but so far 

we are unconvinced that it would be statistically valid 

to add+ 1 to zero and also add+ 1 to a very large number 

in the same population; (2) An attempt to use logs on 

some of the more receptive populations did produce 

more accurate predictor equations and more dramatic 

correlations, but the relative magnitudes of the latter 

remained unchanged from the order given in this text. 

Since the main purpose was to use statistical correlations to delineate geochemical associations, we felt justified in relying on linear functions. 

All data used in this study were obtained from various 

types of analyses of composite samples representing 

1.53-m (5-ft) intersections in rotary drill holes that 

penetrated mineralized carbonate rocks below the zone 

of oxidation. The drill holes were made at 15.3-m (50-ft) 

~ntervals at the intersections of north-south and 

east-west gridlines and represent development drilling 

carried out to establish the volume and grade of ore 

throughout the entire deposit. In order to assure 

coverage of the entire deposit, individual drill holes 

TABLE 1.-Data on elements studied and analytical procedures 

[~pectrographic results are reported to the nearest number in the series 1.5, 1.0, 0. 7, 0.5, 0.3, 

0.2, 0.15, 0.1; analytical error is approximately one standard deviation at plus or minus one 

reporting interval] 

Element Methods of analysis 

Number of Sample~ Analytical ------- precision 

Analyzed ~~~~~;~)! (percentl 

Au --------~t~~!f:so~pti~~-==================~~~ Hg ________ Instrumental meter ________________ 239 

As ________ X-ray fluorescence ------------------ 80 Colorimetric_-------- _______________ 159 Sb ________ X-ray fluorescence ------------------ 80 Colorimetric ________________________ 159 

Ba ________ Spectrographic------------ __________ 292 

X-ray fluorescence ------------------ 80 

Pb ~~ = ________ == = = ===~~:~~~~~:~~:~ Spectrographic--------------- == = = = = ==== = = === == _______ = = = = =~~~ 292 Zn ________ Atomic absorption __________________ 212 

X-ray fluorescence ------------------ 80 

Se {t = = = ________ 

= = = = == =~~i~~r~~~r:~~ Colorimetric--------------------- = == = = = = == = = == = = ==== = 

___ = =~gg 288 Te ________ Atomic absorption __________________ 288 

amounts 

292 

292 

230 

80 

159 

80 

159 

281 

80 

292 

198 

274 

176 

80 

286 

168 

145 

89 

2- 50 2- 50 10- 50 3- 10 10-100 

3- 10 10-100 

3- 10 

2- 50 3- 10 

25-100 

20-100 

5-100 

used for geochemical studies were selected from 

combined geologic and drill location maps. For each of 

the 96 holes chosen, assay and lithologic logs were used 

to help select representative materials from the top,. 

middle, and bottom of each ore zone to achieve a 

complete three-dimensional sampling of the entire 

unoxidized part of the ore deposit. In general at least 

two samples were chosen from each hole. 

Elements included in the study, methods of analyses, 

total number of samples analyzed, and the nurnber of 

samples containing detectable amounts of each element 

are given in table 1. All analyses were performed in 

various laboratory facilities of the U.S. Geological 

Survey in Menlo Park, Calif., and Denver, Colo., as well 

as at the U.S. Bureau of Mines Experimental Station in 

Reno, Nev. 

ACKNOWLEDGMENTS 

We wish to thank the management of Carlin Gold 

Mining Co. for their cooperation and assistance in the 

study. Robert Akright, former resident geologist at the 

mine and presently associated with Occidental Minerals Corp., and Dan Higley of Carlin Gold Mining Co., 

deserve special thanks for their efforts in preparing the 

samples and for assistance in the interpretation of 

rotary drilling information and logs of critical individual drill holes. 

We gratefully acknowledge the help of the many 

individuals in various laboratories of the U.S. Geological Survey as well as at· the U.S. Bureau of Mines 

Experimental Station, Reno, Nev., who carried out the 

analyses that made this study possible. 

Numerous conversations with Professor F. W. 

Dickson, Department of Geology, Stanford University, 

helped to establish chemical parameters for the origin of 

the Carlin deposit. Professor P. Switzer, Departments of 
GENESIS OF THE ORES 3 

FIGURE 1.-The location of the Carlin gold deposit in north-central 

Nevada. 

Statistics and Geology, Stanford University, generously 

criticized the preliminary statistical work, for which we 

are very appreciative. 

GEOLOGIC SETTING 

The Carlin gold deposit, the largest of the disseminated replacement-type gold deposits found to date, is 

located about 64 km northwest of the town of Elko in 

north-central Nevada (fig. 1). Carlin Gold Mining Co., a 

wholly owned subsidiary of Newmont Mining Corp., 

operates the mine, which currently produces about 

2,000 tons of ore per day from three open pits. 

General information on the deposit has been presented in papers by Hardie (1966), Hausen and Kerr 

(1968), and Radtke and Scheiner (1970). A detailed 

geologic map of the deposit was published by Radtke 

(1973) and additional information on the structural and 

stratigraphic setting was included on a regional map of 

the Lynn mining district (Radtke, 1974). For the 

purpose of this paper, a simplified map of the deposit 

(after Radtke, 1973) is shown as figure 2. 

Most of the Carlin ore bodies are in the upper 265+ m 

of the Silurian and Early Devonian Roberts Mountains 

Formation, which is overlain by the Devonian Popovich 

Formation (Akright and others, 1969). The Popovich 

Formation, composed of 80-120 m of alternating thickand thin-bedded silty limestone, is truncated above by 

the Roberts Mountains thrust and is overlain by interbedded shale, chert, and limestone of the Ordovician 

Vinini Formation. 

Host rocks for the Carlin deposit, together with other 

rocks of the lower plate, are exposed in the Tuscarora 

Range. In the central part of the Tuscarora "Range uplift, 

folding, and high-angle faulting accelerated erosion and 

removal of the upper plate rocks to form the Lynn window. The Carlin deposit is located in the northeast 

corner of the Lynn window near the crest of a large 

northwest-plunging anticline where carbonate host 

rocks have undergone intense faulting and brecciation. 

Within the mine area, high-angle faults and breccia 

zones served as main channel ways for ore solutions and 

as structural controls for ore deposition. Radtke (1973) 

showed three sets of high-angle faults including an 

early east-west-trending set, a later north- to northwest-trending set, and a subsequent northeast-trending 

set. The presence of Late Jurassic or Early Cretaceous 

granodiorite dikes along several northwest-trending 

faults and one east-west fault indicate that these faults 

predate the dikes; in many areas the dikes are offset by 

northeast-trending faults confirming the later age of 

these structures. These relations plus the intense hydrothermal alteration of the dikes and the distribution 

of the ore, strongly suggest that the dikes and most of 

the faulting predate the ore formation (Radtke, 1973) 

and that the hydrothermal ore solutions were channeled along preexisting faults. 

GENESIS OF THE ORES 

The ore bodies at the Carlin deposit were formed 

where hydrothermal solutions moving along fault and 

breccia zones penetrated outward into thin-bedded argillaceous carbonate rocks of the Roberts Mountains 

Formation. Reactions between the ore solution and the 

host rock composed mainly of calcite, dolomite, illite, 

and quartz, dissolved the calcite, deposited hydrothermal silica and pyrite, and introduced gold and various 

other elements (Radtke and Scheiner, 1970). A 

generalized sequence for the hydrothermal development of the Carlin ores is shown in figure 3. 

Petrographic examination of host rocks and ores indicates that the initial penetration of the hydrothermal 

fluids resulted in the removal of calcite causing a 

marked increase in permeability of the rocks. This permeability, in turn, had a strong influence on the de-
4 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

EXPLANATION 

[ill . 

. Gold ore Includes both oxidized and unoxidized ore. Most unoxidized 

ore is not exposed 

Granodiorite dike 

Unconformity 

UPPER PLATE OF 

ROBERTS MOUNTAINS THRUST 

Vinini Formation 

Predominantly tan to gray, thinbedded, interlayered siliceous 

shale, chert, and limestone 

WWER PLATE OF 

ROBERTS MOUNTAINS mRUST 

Popovich Formation 

Dark-gray, medium- to thick-bedded 

siliceous dolomitic limestone. 

1::1!?,~§;~ 

Roberts Mountains Formation 

Medium-gray, thin-bedded, siliceous, dolomitic limestone 

)I 

)I 

Contact 

.................... ...4- ..... 

Roberts Mountains thrust 

High -angle normal fault 

Strike and dip of beds 

Outline of pit 

Solid line denotes top of pit wall; 

dashed line denotes toe of pit 

wall. 

FIGURE 2.-Simplified geologic map 
plant 

I 

I 

I 

I 

Ov 

of the Carlin gold deposit. 

GENESIS OF THE ORES 

0 200 400 600 

I I I I 

I I I 

0 100 200 

800 

I 

\ 

1000 FEET 

I 

300 METRES 

5 
6 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

Barite 

~ Quartz + pyrite + 

> Au+Hg+As+Sb 

1-

u 

<( 

..J 

<( As+ Sb+ Hg Cu+Pb+Zn+Mo 

~ sulfides sulfides [[ 

w 

I 

1-

0 

[[ 

0 

>-

I 

~EARLY-----------TIME---------------LATE~ 

FIGURE 3.-Mineralization paragenesis at the Carlin gold deposit. 

velopment of zones favorable for the movement of later 

ore-bearing solutions. 

The main period of gold deposition followed as the ore 

solution removed additional amounts of calcite and 

small amounts of dolomite, and deposited silica, pyrite, 

arsenic, antimony, mercury, and gold. Most of the gold 

and mercury deposited from the solution during this 

phase either is associated with organic materials or, 

along with arsenic and antimony, occurs as coatings on 

pyrite grains (Radtke, Taylor, and Christ, 1972). 

On the basis of electron microprobe studies, Radtke, 

Taylor, and Christ (1972) distinguished four major 

modes of gold occurrences in the unoxidized ore: (1) as 

scattered particles along the rims of amorphous carbon 

grains, (2) as rather homogeneously distributed particles in other kinds of carbon compounds, or as 

gold-organic compounds, (3) as coating on pyrite 

surfaces along with arsenic, antimony, and mercury, 

and ( 4) rarely as free native particles. They found the 

mercury in the unoxidized ore to occur in three principal 

ways: (1) in association with carbonaceous matter, (2) as 

a coating on pyrite grains, and (3) as fine-grained 

cinnabar. 

Any mechanism postulated to explain the transport of 

gold must be compatible with properties of a hydrothermal solution that carried mercury, arsenic, antimony, and quartz. Helgeson and Garrels (1968) used 

thermodynamic evidence to argue for gold transport as 

the aurous chloride species, AuC1 2 -, in acid ore solutions. Later Radtke and Scheiner (1970) attempted to 

use this model to explain many of the observed chemical 

and mineralogic~! features of the Carlin deposit. 

Weissberg (1970) suggested that gold could be transported in alkaline sulfide solutions, and Seward (1973) 

showed that neutral to slightly acidic solutions containing HS- ion would be capable of moving gold under 

geologically feasible conditions. 

Recent work by Rytuba and Dickson (197 4) indicates I 

that in a reducing environment, the chloride ion is not 

effective in transporting gold. Their experimental 

studies also suggest that at elevated temperatures in a 

NaCl-H20 solution reacted with pyrite and quartz, gold 

is in sol uti on as a gold-sulfide complex, presumably 

Au(HS) 2-. 

Arsenic and antimony sulfides and silica are transportable in neutral aqueous solutions lacking excess 

sulfur or chloride ions (Dickson and Tunnell, 1968; 

Weissberg and others, 1966; Kennedy, 1950). However, 

·so far as is known, mercury sulfide is extremely insoluble in any naturally occurring solutions other than 

slightly alkaline (pH 8 to 9) solutions containing dissolved sulfur (Dickson and Tunnell, 1968). Taking into 

account the restrictions imposed on the nature of an ore 

solution capable of simultaneous transport of gold, 

sulfides of mercury, arsenic, and antimony, and silica, it 

is reasonable to conclude that the hydrothermal solution responsible for developing the main stage of the 

Carlin ores was weakly alkaline and contained excess 

dissolved sulfur. -

Although quartz veinlets are very uncommon at Carlin, a few containing small amounts of pyrite, gold, 

fluorite, and frankdicksonite have been found. 

Frankdicksonite, BaF2, was found and described as a 

new mineral by Radtke and Brown (1974). 

Locally the ore solution was trapped in open fractures, and sulfide minerals of arsenic, antimony, and 

mercury were formed. Important minerals containing 

these elements are orpiment, realgar, stibnite, and cinnabar. An apparent segregation exists between sulfides 

or arsenic and stibnite. In areas where orpiment and 

realgar are concentrated, only very small amounts of 

stibnite are present and antimony may substitute for 

arsenic in the structure of orpiment (Radtke, Taylor, 

and Heropoulos, 1974). In contrast, stibnite is concentrated in places that are deficient in arsenic sulfides. 

The position ofbarite in the paragenesis of the deposit 

has been a subject of much speculation and uncertainty. 

Hardie (1966) initially concluded that barite occurrences have no correlation with the presence of gold in 

the mine area. Hausen and Kerr (1968) regarded the 

barite, together with the sphalerite, galena, and part of 

the pyrite, as forming in the Cretaceous, but the gold 

and other minerals forming in the Tertiary. Radtke and 

Scheiner (1970) suggested that barite was transported 

in and deposited from the gold-bearing hydrothermal 

solution, thus making the formation of barite veins and 

the deposition of gold roughly contemporaneous. Detailed geologic mapping suggests that most of the barite 

veins formed after the main phase of gold deposition and 

are either associated with arsenic sulfides or base-metal 

sulfides or are barren and deficient in sulfides (fig. 3). 

Results of stable isotope studies and considerations of 

the chemical model for ore genesis at Carlin support the 
GEOLOGY OF THE ORE BODIES 7 

fact that barite formed late in the paragenetic sequence 

(Dickson and others, 1975). 

Laboratory studies have shown that small amounts of 

various sulfide minerals of copper, molybdenum, lead, 

and zinc occur both in the mineralized limestones and 

locally in barite veins. These four elements show no 

association with gold either on the surfaces of pyrite 

grains or chemically combined with carbonaceous 

materials. They apparently occur only in the form of 

discrete sulfide minerals that formed late in the 

hydrothermal episode after gold deposition. Small 

grains of scheelite randomly scattered through the 

mineralized limestones account for the tungsten in the 

ores. Boron occurs in the clay minerals. The form in 

which the low amounts of selenium and tellurium occur 

has not been determined. 

An important unresolved problem at Carlin is the 

parage netic relation of the mineralization with respect 

to time. The locus of the mineralizing activity varied 

with time not only in its intensity and chemistry but 

also in space. For example, mercury, one of the most 

volatile elements, can be transported aqueously as 

Hg+ +, Hg2 + +, or Hgo but only as Hgo and HgC12, in a 

gaseous phase. Silica and gold (so far as is known) can 

only be transported in solution and not as a vapor. Thus, 

to find an expression for the volatility of the elements in 

the rocks penetrated by mercury, it is necessary to 

examine the distribution pattern of mercury not associated with gold (that is, mercury not introduced in 

the aqueous phase). Unfortunately, we could not find a 

feasible way to do this as almost all samples contained 

detectable amounts of both elements. 

The time distribution of the hydrothermal activity 

seems to fall into three rather broad categories covering 

early, intermediate, and late stages. This report deals 

with the unoxidized ores presumably derived from the 

early and perhaps part of the intermediate stages. However, much of the oxidized zone may have formed from 

processes for which these early stages are responsible 

rather than exclusively from a secondary supergene 

weathering by downward percolating meteoric waters, 

although these certainly did have an effect. The dominantly aqueous, ascending, early mineralization phase 

most probably ranged in temperature from a quite low 

value to the maximum value achieved. If boiling were 

induced, H2S vapor that would be generated would 

stream upward and become oxidized to H2S04. This· 

phase would cause the overlying rocks to be leached and 

altered. The liquors derived from this process would 

then descend, adding sulfate to the subsurface waters 

and acidifying them, causing the deposition of the late 

sulfide-bearing sulfate and carbonate veins. It is also 

possible that descending meteoric waters during this 

stage were superheated and charged with volatiles, and 

the waters thus also rose and joined in the oxidation 

action. 

GEOLOGY OF THE ORE BODIES 

The Carlin gold deposit is made up of three separate 

yet structurally and stratigraphically related ore 

bodies, each of which contains anomalous concentrations of the 13 elements studied statistically. The 

general shape and dimensions of the West, Main, and 

East ore bodies are shown in figure 2. 

The West ore body is almost veinlike in form, strikes 

roughly east-west, dips steeply to the north, and follows 

the hanging-wall side of a normal fault with the same 

attitude (fig. 2). This ore body has strong structural 

controls, contains the smallest amounts of organic 

carbon of any of the ore bodies, and lacks visible 

concentrations of arsenic, antimony, and mercury 

sulfides. 

The Main ore body is actually a northeast-trending 

zone roughly 915 m long within which the gold content 

varies widely. This zone contains numerous individual 

ore bodies, the positions of which are related to sets of 

north- and northeast-trending normal faults. In the 

northeast part of the Main ore body, stratigraphic 

control becomes more dominant; individual o~e bodies 

up to 60 m thick with attitudes similar to the host rocks 

dip about 30°-33° to the north under Popovich Hill 

(fig. 2). 

The Main ore body is characterized by large amounts 

of unoxidized ores of widely varying silica and pyrite 

content. The organic carbon content, which is not uniform, ranges from about 0.1-0.8 weight percent. Sulfide 

minerals of arsenic, antimony, and mercury, and barite 

veins, some of which have associated base-metal 

sulfides, are locally abundant. 

The East ore body is a general term used to describe a 

gold-bearing zone made up of many individual ore 

bodies that occur within a stratigraphic interval of 

100--150 m near, but not at the top of, the Roberts 

Mountains Formation. Northeast-striking faults and 

earlier, dike-filled, northwest-trending faults provide 

primary structural controls (fig. 2), and downdip to the 

west the East ore body may join the Main ore body under 

Popovich Hill. 

Primary unoxidized ores in the East ore body exhibit 

extremely wide variations in the contents of organic 

carbon, silica, and pyrite. The organic carbon content 

usually ranges from 0.5-1.0, and locally it is as high as 

8.0 weight percent. Sulfide minerals are common, 

especially realgar and orpiment, and the element 

thallium, not included in the present study, has been 

found in amounts up to several tenths of a percent by 

weight. 
'5'otr Z.(, 

bS3 

8 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

STATISTICAL ANALYSIS OF GOLD, MERCURY, 

ARSENIC, AND ANTIMONY 

Several workers, including Akright, Radtke, and 

Grimes (1969), Joralemon (1951), Radtke, Dickson, and 

Rytuba (1974), Wells, Stoiser, and Elliott (1969), and 

Wrucke and Armbrustmacher (1975), have established 

that gold, mercury, arsenic, and antimony are ubiquitous constituents of disseminated replacement-type 

gold deposits. The general levels of concentration of 

these elements at the Carlin deposit are established by 

comparing the abundance of each element in 

· mineralized rocks with that in normal carbonate rocks 

in general and the Carlin host rocks in particular 

(table 2). 

Statistical studies were carried out by stepwise linear 

regression analysis to determine the linear relations of 

these four elements and to examine how closely related 

the three elements are to gold by determining the 

statistical dependence of gold values on the values for 

the other three elements. Data used were taken from 

analyses of 239 samples from 96 rotary drill holes 

throughout the mine area. The data, in parts per 

million, had the following characteristics: 

Element Mean 

Au -------------------- 7.2 

fig -------------------- 23 

As -------------------- 507 

Sb -------------------- 126 

Standard deviation 

9.9 

38 

549 

282 

Since these mean values are so much greater than those 

in similar unmineralized rocks near the deposit, we 

concluded that these elements were introduced and 

were not original in situ constituents of the Roberts 

Mountains Formation. The gold value of 7.2 ppm is 

lower than values usually cited for Carlin ores because 

it includes only unoxidized mineralized rocks 'and 

excludes certain areas of higher grade oxide ores and 

also because it includes large tonnages of mineralized 

rocks of lower grade now considered to be ore at gold 

prices of $140 to $160 per ounce. 

TABLE 2.-Abundance of gold, mercury, arsenic, and antimony in fresh 

limestones and unmineralized carbonate host rocks and unoxidized 

gold ores at the Carlin deposit 

[All values in parts per million. N, not determined; X, order of mag_nitude estimate] 

Fresh carbo-· Fresh carbo- Carbonate host rocks, Mineralized carbonate 

nate rocks' nate rocks2 Carlin deposit" rocks, Carlin deposit4 

Element 

Average Average Average Median Average Median 

Au ______ . o.oox 0.005-0.009 <0.02 <0.02 11 10 

fig------ 0.00 0.07 0.08 0.07 25 30 

As ------ 1. 2.5±1.0? 4(?} N 480 360 

Sb ------ 0.2 0.2±0.1? 0.8 0.5 130 90 

'Abundance in carbonate rocks in the Earth's crust (Turekian and Wedepohl, 1961). 2Abundance in carbonate rocks (Graf, 1960). 3Values for fresh unmineralized Roberts Mountains Formation (Radtke and others, 1972; 

Radtke, unpublished data). . 4Values for unoxidized mineralized Roberts Mountains Formation (Radtke and others, 

1972). 

Krumbein (1959) suggested that it is reasonable to 

make the assumption that independent variables 

(mercury, arsenic, and (or) antimony in this study) that 

show the strongest mathematical correlation to the 

dependent variable gold also have the strongest 

physical relation to the phenomenon being studied. 

Obviously, many factors besides the ones used influenced the deposition of gold. However, as an indication 

of association, linear correlation coefficients may be 

valuable even though the variables compared may or 

may not be related by simple cause and effect. The 

nature of any relation is expressed by a correlation 

coefficient that ranges from -1 (perfect negative 

correlation) through 0 (absolutely no correlation) to + 1 

(perfect positive correlation). 

The least-squares method finds a linear function that 

minimizes the sum of the squared deviations between 

observed gold values (Yi) arid the calculated gold values 

('£), 

where 

ti=a0 +a1x1 +a2x2+a3x3+ ... +a17x11 

where av a 2, ... a11 are the least-squares 

coefficients associated with xv x2, ... x 11 

independent variables, and 

a 0 = Y intercept. 

This method will minimize: I(t i-Y i)2. 

The percent reduction in variance due to a linear model 

(R2) is given by: 

R2= 1 _ ICti-Yi)2 

ICYi-Y)2 

where Y is the average of all gold values. 

Comparison of the four elements showed them to have 

the following linear correlation coefficients over the 

entire deposit: 

(1) Au to Hg:0.44 

(2) As to Hg:0.32 

(3) Au to As:0.26 

( 4) As to Sb:0.22 

(5) Au to Sb:0.11 

(6) Hg to Sb:0.07 

Upon reviewing the results of these correlations, we 

found that by eliminating approximately 1 percent of 

the samples from the en~ire population, much better 

correlations' could be obtained. The eliminated samples 

were those that had created the greatest amount of 

variance from the proposed linear models. Scatter plots 

of these new populations with the anomalous values 

deleted are shown in figure 4. Inspection of the aberrant 

samples showed that some contained highly anomalous 

values, usually of mercury or arsenic, that probably 
STATISTICAL ANALYSIS OF GOLD, MERCURY, ARSENIC, AND ANTIMONY 

BMDOSO GENER-L PLOT • INCLU~ING HISTOGRAM • REVISED JANUARY 30t 1970 

HEALTH SCIENCES COMPUTING FACILlTYt UCLA 

z 

0 

...j 

~ :E 

at 

1&1 

0.. 

Ill 

.... 

at 

0.. "" 

.; 

at 

::I 

u 

at 

1&1 

:a: 

GOLD•MERCURY REVISED DATA SCATTER PLOT FOR UNOXIDlZED ORE 

PLOT OF VARIABLE 2 IIIERTIC~L AXISI VER.SUS VARIABLEISI 1 ISYMBOL=61, 

•7o500 7o500 22oSOO 37.500 -o.ooo 15.000 3o.ooo 52.500 67.500 

45.000 60.000 

•••••••••••••••••••••••••••••• + •••••.••••••••••••••••••••••••••••••••••••••• + ••••••••••••••••••••••••• 

172.000 . 

152.000 • 

132o000 . 

112.000 • 

92.000 . • 6 

• . 72.000 • 

0 

• 

• 52.000 • • 0 6 0 

.. 3 0 2 0 • 2• • 2 02 II 

32.000 . • • 20 

2 3 .. 35 2 Z.•oo • • 0 0 00 

z•• • • •32 00 

24° 2 20°2° • 00 

12.000 . 262 3 0 • 

39862•• 

•F46o• o o 0 

296••42 00 • 0 

-a.ooo • 

•..•••.••••••.••.•..•..•.•..•.•••.••....•.•..•.....•....•....•....•....•....•....•....•....•....•....• •1oS00 7o500 22o500 37.500 52.500 67.500 

-o.ooo 15.000 3o.ooo 45.000 60.000 

GOLDe PARTS PER MILLION 

9 

172.000 

152·000 

132.000 

ll2o000 

92·000 

72.000 

52.000 

J2o000 

12.000 

-a.ooo 

FIGURE 4.-Direct scatter plots of gold, mercury, arsenic, and antimony in unoxidized Carlin ores. Plots are: A, Au to Hg; B, Au to As; 

C, Au to·Sb; D, Hg to As; E, Hg to Sb; F, Sb to As. 

The following symbols represent ties of more than one point I significantly from the means for the original data, but 

occurring at the same coordinates: the standard deviations were reduced for most samples. 

Number of Number of Number of When the revised set of data was treated as one 

Symbol points Symbol points Symbol points 

2 2 8 8 E" 14 population over the entire area of the deposit, the 

3 3 9 9 F 15 results obtained in parts per million were: 

4 4 A 10 G 16 Element Mean Standard deviation 

5 5 B 11 H 17 Au -------------------- 6.6 8.9 

6 6 C 12 18 Hg -------------------- 21 22 

7 7 D 13 >18 As -------------------- 502 515 

were due to pieces of cinnabar, realgar, or orpiment. 

Most of them contained combinations of values that 

were incompatible with the proposed function. The 

means found for this revised data set do not differ 

Sb -----------,--------- 123 185 

and the linear correlation coefficients were: \ 

(1) Au to Hg:0.55 

(2) As tQ Hg:0.27 

(3) Au to As:0.27 
10 

z 

::! 

~ 

~ 

i 

II: 

.., 

Q,. 

VJ 

... 

0: 

c 

0.. 

u 

z .., 

en 

a: 

c 

STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

BMDOSD GENERAL PLOT - INCLUDING HISTOGRAM - REVISED JANUARY 30t 1970 

HEALTH SCIENCES COMPUTING FACILITYt UCLA 

GOLD-ARSENIC REVISED DATA SCATTER PLOT FOR UNOXIOIZED OR[ 

PLOT Or VARIABLE 3 CVERTICAL AXIS) VERSUS VARIABLECSI 1 CSYMBOL•*lt 

-7oSOO 7o500 22o500 37.500 -o.ooo 15.000 3o.ooo 

52.500 67.500 

45.000 60o00.0 

••...•....•....•....•....•....•.... ~ ....•....•....•.•..•....•....•....•....•.••.•....•....•....•....• 

J7SO.ooo • 

3375.000 • 

3000.000 

2625.000 

zzso.ooo • 

1875.000 • 

1500.000 • 

1125.000 • 

750.000 • 

3rs..ooo • 

o.o 

• 

• 

• 

• 

•• 

• 

• 

• 

• • 

• 

• • 

• 

•• • 

•• • 2• 

• • 

•••• •• • • •2• ••• 

3• •• 2 • • • • 

3 2 •2 •• 2 

542• 3• -3 2 • •• 345323•• 3° •• 93325 • • • 

•E63 2 •• • 4863 • • 

• 

• 

• • • 

• • • 

• 

• •• • • 

• • • • 

• 

• • • 

2 • 

•• • 

• 

• 

•7e500 ···········~·························································································· 7o500 22o500 37.500 52.500 67.500 

-o.ooo 15.000 3o.ooo 45.000 60.ooo 

GOLD• PARTS PER MILLION 

FIGURE 4.-Continued. Explanation on page 9. 

J?so.ooo 

3375.000 

3000·000 

2625o000 

zzso.ooo 

tns.ooo 

15oo.ooo 

112So000 

750 .• 000 

375.000 

o.o 

( 4) As to Sb:0.22 

(5) Au to Sb:0.12 

(6) Hg to Sb:0.05 

the correlation is not significant at the 95-percentconfidence level. 

The revised means and standard deviations for each 

of the three ore bodies are summarized in table 3, and 

linear correlation coefficients for each pair of elements 

in each ore body are shown in table 4. 

These correlation coefficients (R) are strictly applicable only to the data used in the computations. It is our 

hope that they reflect the correlation coefficients (p) of 

the true population of these elements in the ore bodies at 

Carlin. We want to establish whether the range of 

values within which p falls includes zero, in which case 

It is modeled that ¥2 In (1 + R/1-R) can be considered 

to have an approximately normal distribution with a 

standard deviation of 1/Y'Y]-3. Hence, the 95-percentconfidence interval for p is: 

1 1+R 1.96 1 In 1+p -In V71 -3 < - 2 1-R 2 1-p 

1 1+R 1.96 

< - In -- + 2 1-R \111-3 

where 17 = number of samples. 
STATISTICAL ANALYSIS OF GOLD, MERCURY, ARSENIC, AND ANTIMONY 

BMOOSD GENERAL PLOT • INCLUOING HISTOGRAM • REVISEO JANUARY JOt 1970 

HEALTH SCtF.NCES COMPUTING FACILITY• UCLA 

z 

~ ..J 

..J 

~ 

Q: 

w 

Q. 

~ Q: 

Cl 

Q. 

;. 

z 

0 

~ 

~ 

z 

Cl 

GOLD-ANTIMONY REVISED DATA SCATTER PLOT FOR UNOXIDIZED OAE 

PLOT OF VARIABLE 4 CV[RTICAL AXIS1 VERSUS VARIABLEISI 1 ISYMBOL=0 1o 

4500.000 

4000.000 

3500.000 

3000.000 

2500.000 

zooo.ooo 

1500.000 

1000.000 

soo.oon 

o.o 

-soo.ooo 

-7.500 7.500 ~2.500 31.500 52oSOO 67.500 

. 

. 

. 

. 

. 

. 

. 

. 

• 

-o.ooo 15.000 30.000 45.000 60.000 

..................................................................................................... 

2 52332 22 022 202 00 0 200 020 

?.lFQ~A35 75302022032 o 30 zooo 

1115 2 2 

00 0 

..................................................................................................... -7.sno 7.soo 22.500 37.500 s2.soo 67.Soo 

-o.ooo 15.000 30.000 45.000 60.000 

I.OLOo PARTS PER MILLION 

FIGURE 4.-Continued. Explanation on page 9. 

11 

4Soo.ooo 

40oo.ooo 

3500o000 

aooo.ooo 

2500·000 

2000·000 

tsoo .• ooo 

lOOOoOOO 

soo.ooo 

o.n 

-soo.ooo 

TABLE 3.-Mean values and standard deviations for gold, mercury, 

arsenic, and antimony in the West, Main, and East ore bodies at the 

TABLE 4.-Linear correlation coefficients between gold, mercury, 

arsenic, and antimony for the West, Main, and East ore bodies at the 

Carlin gold deposit 

Carlin gold deposit 

[All values in parts per million] West ore body Main ore body East ore body 

West ore body Main ore body East ore body Element pair Correlation Element pair Correlation Element pair Correlation 

coefficient coefficient coefficient 

Element 

Mean Standard Mean Standard Mean Standard 

deviation deviation deviation Sb to As _______ 0.87 Au to Hg ______ 0.62 Au to Hg ______ 0.48 

Au to Sb ______ .85 Au to Sb .62 Au to As .23 

Au------------ 7.5 8.4 6.5 8.2 6.4 9.4 Au to As ______ .81 Sb to As .47 As to Hg .19 

Hg ------------ 22 20 20 25 21 21 Au to Hg ______ .68 As to Hg .41 As to Sb .19 

As ------------ 222 220 490 540 590 580 Sb to Hg .56 Sb to Hg .40 Au to Sb .08 

Sb ------------ 52 40 106 76 155 382 As to Hg ______ .54 Au to As .34 Sb to Hg .00 
12 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

z 

8 

..J 

;::! 

X 

·0:: 

1&.1 

Q. 

C/1 

..... 

ex 

"" Q. 

u 

z 

1&.1 

C/1 

ex 

c 

BMDOSD GENERAL PLOT • INCLUDING HISTOGRAM • REVISE6 JANUARY 30t 1970 

HEALTH SCIE~CES COMPUTING FACILITY• UCLA 

MERCURY-ARSENIC REVISED DATA· SCATTER PLOT FOR UNOXIniZEO ORE 

PLOT OF VARIABLE 3 IVERTICAL.AXISI VERSUS VARIABLEISI 2 ISYMB~L=Mle 

-o.ooo 4o.ooo ao.ooo 12o.ooo .-zo.ooo 20.000 60.000 1oo.ooo 

160.000 

l40.no.o 

•••·•·••••••••••••·••••••·••···•····•····•····•·•··•·····•··•·••···•····•····•····•····•····•····•···· 375o·.ooo . M M 

3375.000 . 

. 3000.000 • 

M 

2625.000 . 

2250.000 . M 

. 1875.000 • M 

M 

M M 

tsoo.ooo. . M 

M M 

H 

. M M 

1125.000 • 2 M M 

M M M M M 

M 

M?.M MZM M M 

750.000 . M 2MM 2 H 2 M M 

M MM2 MM M M M M M MMM 2 2 MM M M M M M M 

MM 3M HH M M MM 

375.000 • 23323 2MM3 2 2 M 2 42MM44 M2HMMM2 MM M 

4422M M2MM MMM M M MM MM M 

76H3MM3M M 2M 2 M 353M3• M M 2 M M M 

o.o M 

••·•·••····•••·•••·•••···••··•·••···•···••····•····•····•····•····•·•··•····••··•••···•····••···•···· -o.ooo 4o.ooo eo.ooo 12o.ooo 16o.ooo 

-zo.ooo 20.000 60.000 100.000 140.000 

MERCURYi PARTS PER MILLION 

FIGURE 4.-Continued. Explanation on page 9. 

nso.ooo 

JJ"''SoOOO 

3000.000 

2625·000 

2250·000 

1875.000 

1125.000 

"1'50·000 

375.000 

o.o 

1.96 is obtained from the normal distribution tables so 

that there is a 95-percent probability that plies between 

the two limits. 

functions with all the independent variables entered in 

parts per million: 

The correlation coefficients calculated at the 95-

percent-confidence level were: 

Sb to As, R=0.87 Au to Hg, R=0.68 

0.77 < p < 0.93 0.46 < p < 0.82 

Au to Sb, R=0.85 Sb to Hg, R=0.56 

0.72 < p < 0.92 0.30 < p < 0.75 

Au to As, R=0.81 As to Hg, R=0.54 

0.66 < p < 0.90 0.26 < p < 0.73 

The least-squares predictor equations for the mean 

gold content may be computed by the following three 

(A) West ore body: 

E(Au) = -2.22959 + 0.11746 (Hg) + 

0.00833 (As) + 0.10364 (Sb) 

(B) Main ore body: 

E(Au) = -1.20076 + 0.14972 (Hg) -

0.00105 (As) + 0.04956 (Sb) 

(C) East ore body: 

E(Au) = 0. 79597 + 0.19946 (Hg) + 

0.00203 (As) + 0.00132 (Sb) 

The percent reductions in variance due to a linear 

model [R2=1-I. (sample gold values-computed gold 
STATISTICAL ANALYSIS OF GOLD, MERCURY, ARSENIC, AND ANTIMONY 

8MD05D GENERAL PLOT • INCLUDING HISTOGRAM • REVISED JANUARY 30t 1970 

HEALTH SCIENCES COMPUTING FACILITY• UCLA 

MERCURY-ANTIMONY REVISED UAT~ SCATTER PLOT FOR UNOXIOIZEn ORf 

PLOT OF VARIABLE 4 CVF.RTICAL AXJS) VERSUS VARlAALE!S) Z !SYMBOL•M)o -o.ooo 4o.ooo eo.ooo 12o.ooo tflo.ooo -zo.ooo lO.ooo ~o.ooo 10o.ooo 14o.ooo 

13 

.••....•....•••.••.•.••.•..•....•....•....•...••••.••...••.••.•.•...•....•....•....•....•...••....•.... 

4500.000 • . • 4500o000 

•. 

4000.000 . 

3500.000 

3000.000 . z 

0 

~ 2500.000 . ~ % 

a: 

.w 

Q. 

2000.000 . Ill 

.. 

a: 

Cl 

Q. 

; . z 1500.000 • 0 

~ .. 

z 

c 

1000.000 . 

soo.ooo 

o.o 

•50o.ooo • 

M 

H 

M 

M M HM 2 M 

2M222MM2 MM337M 2MMMM M2 2 

99975625762654 SM 4233MM M M M 

88449654 2M22 MM M 2M 

M 

M 

2 MM M 

MM M H 

4000.000 

3500.000 

30oo.ooo 

2500o000 

zooo.ooo 

1500·000 

1000.000 

500o000 

o.o 

-soo.ooo 

••...••.•.••....•...••....•.•..•....•....•.••••.•..•.•..•....•....•....•....•....•....•....•....•.... -o.ooo •o.ooo eo.ooo 12o.ooo 160.ooo 

-zo.ooo 20.000 60.000 -lOOoOOO 140.000 

MERCURY• PARTS PER MILLION 

FIGURE 4.-Continued. Explanation on page 9. 

values)2/I(sample gold values-mean gold values)2] 

using these functions are: (A) West ore body-79.22 

percent, (B) Main ore body-54.90 percent, (C) East ore 

body-25.01 percent. A linear model fits the West ore 

body quite well. 

The standard error of prediction (SE) of using these 

three variables to predict the mean gold value is 

determined by 

SE =(Mean square of residuals)lh 'Y} 

= [I i = 1 (Sample Au value-computed Au value)2J'h 

(number of samples- number of variables -1) 

where 'Y} is the number of samples and i=l is the first 

sample considered. 

The standard errors found in the above linear 

functions (A, B, and C) are (A) West ore body=3.9 ppm, 

(B) Main ore body=5.6 ppm, and (C) East ore body=8.2 

ppm. 

The multiple correlation coefficients, defined as the 

square root of the percent reduction in variance and 

used as a measure of the adequacy of the different 

values in predicting the mean gold value (Krumbein 

and Graybill, 1965), were found to be 

West ore body 

As:0.89 

Hg:0.88 

Sb:0.85 

Main ore body 

As:0.74 

Sb:0.74 

Hg:0.62 

East ore body 

Sb:0.50 

As:0.50 

Hg:0.48 
14 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

BMDOSD GENERAL PLOT - INCLUDING HISTOGRAM - REVISED JANUARY 30t 1970 

HEALTH SCIENCES COMPUTING FACILITY• UCLA 

ANTIMONY-ARSENIC REVISED DATA SCATTER PLOT FOR UNOXIDIZED ORE 

PLOT OF VARIABLE 3 (VERTICAL AXISI VERSUS VARIABLF.IS) 4 !SYMROL•Sit o.o aoo.ooo 16oo.ooo 24oo.ooo 3200.000 •ooo.ooo 400.000 1200.000 2000.000 2800.000 3600.000 

•·••·•·•··•••··•····•·····•····•····•····•····•····•····•····•····•····•····•····•····•····•····•····• 3750.000 • :nso.ooo 

s s s 

3375.000 . 337'5oOOn 

3000.000 31ioo.onn 

s 

2625.000 • 2625oOOn 

s 

z 

g 2250.000 • 22so.ono ...J 

;:! 

% s .a:: 

w 1875.000 • Q. 187'5oOiln 

Cll . ss .... 5 a: 

Q. "" 55 

u 1500.000 • s 1500o000 . s s z 

w 

Cll s a:: s s "" 1125.000 • 5 55 s 112s.oon . SS52 s. 5 • S3S 25 s s 750.000 • SSS3 7Sn.oon 

. 2 325 . 5654 . SS354S • 263 s 37S.ooo • S894S S 375o.OOO • 9D4 s s • 81 2 

.2/JS 

oBF o.o •S o.o ...................................................................................................... 

o.o eoo.ooo 16oo.ooo 240o.ooo 3zoo.ooo 4ooo.ooo 

400.000 1200.000 zooo.ooo zeoo.ooo· 3600.ooo 

ANTIMONY• PARTS PER MILLION 

FIGURE 4.-Continued. Explanation on page 9. 

By using the linear model with the revised data from 

the entire deposit, the variance is decreased by 31.8 

percent with mercury accounting for 93.8 percent of the 

reduction. The least-squares equation is: 

E(Au) = 1.21723 +0.20225 (Hg) 

+0.00186 (As)+0.00209 (Sb). 

The standard error of estimate is 7.35 ppm. Multiple 

correlation coefficients for the variables in the equation 

are: 

Hg:0.55, As:0.56, and Sb:0.56. 

Some interesting relationships appear when correlations are compared to the mean values in the three ore 

bodies. Gold content is fairly constant between the three 

areas, but the arsenic content is much lower in the West 

ore body than in the other two. However, the correlation 

between the gold and arsenic is fairly high (0.81) in the 

West ore body, whereas the correlations in the Main and 

East ore bodies (0.34 and 0.23, respectively) show much 

less dependence of one on the other. Graf(1960) reported 

that carbonate rocks normally contain only 1 or 2 ppm of 

arsenic unless there is an abundance of carbonaceous 

material, iron oxides, or sulfides present. Information 

derived from samples of the fresh unmineralized 

Roberts Mountains Formation around Carlin (Radtke, 

Heropoulos, Fabbi, Scheiner, and Essington, 1972) 

indicates that this observation holds true here. They 
STATISTICAL ANALYSIS OF GOLD, MERCURY, ARSENIC, AND ANTIMONY 15 

reported that although only 2 out of 15 samples had 

detectable amounts of arsenic (10 ppm), some rocks 

contained as much as 0.5 percent syngenetic pyrite and 

as much as 1 percent organic carbon. 

The very high Au:As correlation may be partly 

explained in the following three ways: 

(1) Gold and arsenic appear to have been coprecipitated on the surface of pyrite grains. 

(2) The Main and East ore bodies are characterized 

by an apparent late buildup of arsenic as evidenced by 

the presence of arsenic sulfides in these two areas. 

(3) The host rocks for the West ore body contain 

relatively small amounts of the carbonaceous materials 

that tend to induce precipitation of gold and mercury, 

but not arsenic, elsewhere in the deposit. Consequently, 

the deposition of gold as well as arsenic in this area was 

apparently more responsive to physicochemical factors 

such as fluctuations in the compositions of the invading 

solutions and (or) changes in pH, temperature, and 

pressure than in other areas. The West ore body 

probably formed under a more uniform set of chemical 

conditions that existed during the earlier part of the 

mineralizing sequence. Since the late arsenic, antimony, mercury sulfide stage is lacking in this area, the 

high Au:As correlation in the West ore body suggests 

that deposition of gold and arsenic in early stages of 

mineralization occurred under similar physicochemical 

conditions. 

The content of antimony is also very much lower in 

the West ore body than in the other two. The correlation 

between antimony and arsenic is much higher in the 

West ore body (0.87) than in the Main and East ore 

bodies (which have values of0.47 and 0.19, respectively). The relation of antimony to gold shows a similar 

trend. In the West ore body, where antimony has its 

lowest mean value, the correlation is strongest, whereas 

in the East ore body, which has the highest mean 

antimony value, the correlation is very weak. 

The poor As:Sb correlation in the East ore body is 

explained by the presence of antimony as late-formed 

and unevenly distributed pods of stibnite, whereas 

arsenic occurs as random scatterings of arsenic sulfides. 

Mineralogical studies show that there is almost no 

correlation between the occurrences of the antimony 

and arsenic sulfides within the Main and East ore 

bodies. In rocks that contain realgar and (or) orpiment, 

there is usually little stibnite, concentrations ·of which 

are almost invariably marked by the absence of arsenic 

sulfides. This observation was confirmed by the values 

of the correlation coefficients. The low correlations 

between gold and antimony and gold and arsenic in the 

Main and East ore bodies may be explained by the 

higher content of organic carbon in these areas that 

removed large amounts of gold and mercury from the 

hydrothermal solutiOJ?.S. The correlations between gold 

and mercury are the strongest correlations between any 

element pairs in carbonaceous areas. The stronger gold 

to mercury correlation also reflects their coeval deposition on the surface of pyrite grains. 

Within the host rocks of the West ore body, that had 

less carbon to fix gold and mercury, a simple 

paragenesis developed in which gold, mercury, arsenic, 

and antimony were all deposited together in response to 

physicochemical conditions that changed in a consistent 

direction. Relations between elements in the West ore 

body are those that occurred in the presence oflimited or 

small amounts of organic carbon. In the Main and East 

ore bodies, larger amounts of organic carbon caused 

early deposition of gold and mercury, thus the 

paragenesis was complicated by depleting the ore fluid 

in these elements and leaving significant amounts of 

arsenic and antimony to be deposited in a later 

depositional stage. 

Distributions and relations of these four elements 

between the three ore bodies were compared by stepwise 

discriminant analysis. Discriminant analysis makes 

linear combinations of the four quantitative variables 

to produce two (number of qualitative variables, that is, 

the three ore bodies, minus one) pseudovariables called 

the canonical variables. These are chosen so as to: (1) 

minimize the squared distance from a sample point to 

the plot of the mean of its respective ore body on a graph 

with the canonical variables as axes; and (2) maximize 

the separations of the pits; that is, maximize the 

distance between the plots of the pit means. The 

canonical variables thus produce two optimum linear 

functions (L1 and L2) from the original four variables so 

that when the samples from each site are evaluated 

with these functions, they are best separated from the 

samples of the other areas. Consequently, when the 

data points are plotted in a L1, L2 graph, the three sites 

have the greatest mutual separation. 

Listed below are the values found for each element in 

terms of percentages of samples nearest to the different 

ore body means, that is, the values are percentages of 

samples taken from the vertically listed ore bodies 

whose mean values are closest to the mean of the 

horizontally listed ore bodies. It is important to note 

that arsenic values would be included in the second step, 

gold and arsenic would be included in the third step, and 

all values are used in the computations for the final step 

below. 

Step 1, Arsenic: 

East _______________ _ 

Main---------------- VVest _______________ _ 

East 

41.13 

27.14 

5.4 

Main 

20.16 

20.0 

8.11 

West 

38.71 

52.86 

86.49 
16 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

Step 2, gold and arsenic: 

East Main West 

East ---------------- 30.64 42.74 26.62 

Main __ --,------------ 20.0 30.0 50.0 

West---------------- 0.0 8.11 91.89 

Step 3, antimony, gold, and arsenic: 

East Main West 

East ---------------- 32.26 43.55 24.19 

Main ____ ---------- __ 21.43 31.43 47.14 

West---------------- 0.0 8.11 91.89 

Step 4, mercury, antimony, gold, and arsenic: 

East Main West 

East ---------------- 34.68 37.10 28.22 

Main ________________ 20.0 42.86 37.14 

West ________________ 0.0 10.81 89.19 

When various combinations of the elements were 

compared between the ore bodies in this fashion, the 

West ore body consistently showed the greatest polarization. That is, values of arsenic, gold and arsenic 

together, antimony, gold and arsenic together, and 

mercury, antimony, gold and arsenic together in the 

West ore body were always much closer to the mean 

value in that ore body than to the mean values in the 

other two ore bodies. These values also reflect the much 

higher correlations between elements in the gold, 

mercury, arsenic, antimony suite in the West ore body. 

Values for these suites of elements in the Main ore body 

tend to be much more similar to the West ore body than 

to the East ore body. 

Strong polarization of the West ore body is probably 

due also to the relation of the mean values (given 

earlier) where, except for gold and mercury that show 

little variation between the three areas, the values in 

the West ore body are drastically lower. This reflects the 

different chemical conditions originally present in this 

area, which were previously described. 

The polarity of the element values in the West ore 

body support the proposed mineral paragenesis model 

(fig. 3) in which the late mercury, antimony, and arsenic 

sulfide mineralization occurred only in the Main and 

East ore bodies. 

The relatively high correlation between gold and 

mercury found for the entire deposit was probably 

caused by two conditions: (1) gold and mercury were 

both transported in the same ore solution and were 

removed from that solution simultaneously in response 

to similar influences; and (2) more than 90 percent of the 

occurrences of both elements either are associated with 

various organic materials or occur together on the 

surfaces of pyrite grains; the occurrences reflect a 

similar depositional process for both elements. Both of 

these conditions represent deposition on fine-grained 

materials that are fairly evenly distributed throughout 

the volume of mineralized rocks in the entire deposit. 

The removal of gold and mercury from solution probably 

reflects the extraction capability of various solids on 

complexes of these metals in highly supersaturated 

solutions, and this extraction capability led to their 

precipitation in fairly constant proportions. The processes responsible for the deposition of gold and mercury in 

highly carbonaceous rocks were probably not the same 

as those leading to the precipitation of arsenic and (or) 

antimony. 

STATISTICAL ANALYSIS OF GOLD, BARIUM, 

COPPER, MOLYBDENUM, LEAD, AND ZINC 

The fact that anomalous amounts of barium, copper, 

molybdenum, lead, and zinc occur in areas of disseminated gold mineralization has been pointed out by 

Akright, Radtke, and Grimes (1969); Radtke, Heropoulos, Fabbi, Scheiner, and Essington (1972); and Wrucke 

and Armbrustmacher (1975). Comparison of data for 

normal limestones and unmineralized host rocks with 

mineralized rocks (table 5) shows that, except for 

barium, these elements are concentrated from about 4 

to 10 times in the ores. The content of barium is slightly 

increased in the mineralized unoxidized ores. These 

concentration factors are significantly less than the 

general range of 100 to 500 times for gold, mercury, 

arsenic, and antimony (table 2). 

Data from analyses of 292 1.53-m (5-ft) composite 

samples taken from 96 rotary drill holes in unoxidized 

gold-bearing rocks were used to find the correlations 

between gold, barium, copper, molybdenum, lead, and 

zinc. A stepwise linear-regression analysis was performed to find the dependence of gold on the other five 

elements throughout the entire deposit, and then it was 

done for each of the three ore bodies individually. Then 

the elements were compared between the ore bodies by 

means of a stepwise discriminant analysis. The data, in 

parts per million, had the following characteristics 

taken over the three ore bodies: 

Element Mean Standard deviation 

Au -------------------- 7.3 10 

Ba -------------------- 400 200 

Cu -------------------- 33 15 

Mo -------------------- 5.9 6.9 

Pb -------------------- 30 99 

Zn -------------------- 165 665 

These mean values compare well with those reported 

for Carlin ores cited in table 5. The lower computed 

mean value for gold was explained previously in this 

report. The difference in zinc values is not significant in 

view of the large standard deviation. 

Linear correlation coefficients found over the entire 

deposit are, in decending order: 

(1) Au to Zn:0.20 (5) Zn to Cu:0.07 

(2) Cu to Mo:0.19 (6) Au to Mo:0.06 

(3) Au to Cu:0.17 (7) Au to Ba:-0.06 

(4) Cu to Ba:-0.08 (8) Ph to Mo:-0.05 
STATISTICAL ANALYSIS OF GOLD, BARIUM, COPPER, MOLYBDENUM, LEAD,AND ZINC 17 

(9) Pb to Ba:0.05 

(10) Au to Ph: -0.05 

(11) Ph to Zn:0.04 

(12) Mo to Ba:0.03 

(13)Pb to Cu: -0.02 

(14) Zn to Ba:0.01 

(15) Zn to Mo: -0.01 

All correlations between these elements are weak. 

The weaknesses may in part be attributed to the fact 

that many of these elements were analyzed by 

semiquantitative spectrographic analysis rather than 

by the more precise methods used for the previous suite 

of elements. 

TABLE 5.-A bundance of gold, barium, copper, molybdenum, lead, and 

zinc in fresh limestones and unmineralized carbonate host rocks and 

unoxidized gold ores at the Carlin deposit 

[All values in parts per million. N, not determined or calculated· 

X, order of magnitude estimate] ' 

Fresh carbo- Fresh carbo- Carbonate host rocks, Mineralized carbonate 

Element nate rocks' nate rocks2 Carlin deposita rocks, Carlin deposit• 

Average Average Average Median Average Median 

Au ______ o.oox 0.005-0.009 <0.02 <0.02 11 10 

Ba ------ 10 150±110 250 280 400 500 

Cu ------ 4 14±9 9 15 35 30 Mo ______ 0.4 1.1±0.7? <2 <2 7 5 

Ph ------ 9 8±4 3 N 30 20 

Zn ------ 20 26±5 14 11 185 120 

'Abundance in carbonate rocks in the Earth's crust (Turekian and Wedepohl 1961) 2Abundance in carbonate rocks (Graf, 1960). ' · 3Values for fresh unmineralized Roberts Mountains Formation (Radtke and others 1972· Radtke, unpublished data). ' ' •Values for unoxidized mineralized Roberts Mountains Formation (Radtke and others 

1972; Radtke, unpublished data). ' 

Irregularities in the barium and associated basemetal distributions were predictable from geologic 

occurrences of the mineral phases involved. Small 

amounts of barium occurs as barite that is scattered 

through the mineralized carbonate rocks. Most of the 

barite, however, is concentrated in late veins that follow 

faults and fracture zones in the upper oxidized parts of 

the ore bodies. The erratic distribution and irregular 

shapes of the barite veins, only some of which contain 

sulfide minerals, account for local high anomalies in 

these elements. Genesis of barite in the Carlin ores was 

discussed in detail by Dickson, Radtke, and Rye (1975). 

Detailed electron microprobe studies of Carlin ores 

(Radtke and others, 1972), including analyses of pyrite 

grains and carbonaceous materials known to contain 

gold and mercury, showed that copper, molybdenum, 

lead, and zinc do not occur in this association. These four 

elements do occur, however, as discrete sulfides locally 

concentrated in barite veins and erratically scattered 

through mineralized rocks. This distribution of these 

base-metal sulfides tends to produce insignificant 

correlations between these four elements. 

Because the three ore bodies at Carlin are known to 

possess different geologic and mineralogic characteristics, the correlations between the six elements were 

examined for each individual ore body. Mean values and 

standard deviations for gold, barium, copper, molybdenum, lead, and zinc in each ore body are given in table 

TABLE 6.-Mean values and standard deviations for gold, barium, 

copper, molybdenum, lead, and zinc in the West, Main, and East ore 

bodies at the Carlin gold deposit 

[All values in parts per million] 

West ore body Main ore body East ore body 

Element 

Mean Standard Mean Standard Mean Standard 

deviation deviation deviation 

Au------------ 8.6 10 6.9 8.9 7.2 11 

Ba ------------ 650 330 500 200 300 100 

Cu ------------ 25 13 36 18 33 13 Mo ____________ 6.2 9.3 7.3 6.1 5.0 6.3 

Ph ------------ 26 51 49 175 20 19 

Zn ------------ 7 72 193 197 177 890 

6. Linear correlation coefficients for gold, barium, 

copper, molybdenum, lead, and zinc within each ore 

body, listed in descending order, are shown in table 7. 

Correlation coefficients show that for the Main and 

East ore bodies most of the correlations between pairs of 

these six elements are very low. Only in the West ore 

body do the correlation coefficients show any consistent 

relations predictable from the geochemical paragenetic 

model. Correlations between pairs of base metals and 

between zinc and barium are relatively uniform and 

strong compared to those between the other base metals 

to barium, gol~ to the base metals, and gold to barium. 

These correlations reflect the fact that the base metals 

were deposited during a stage in the hydrothermal 

paragenesis separate from that of gold, and that 

although some barite formed as base metals were 

deposited, most of the barite was deposited later in the 

paragenesis (Dickson, and others, 1975). 

That the West ore body is best represented by a linear 

model is entirely consistent with the following known 

geologic facts: the West ore body has the most simple 

structural setting of the three ore bodies; the mineralization in this area included the entire hydrothermal 

sequence except for the late, postgold, mercuryTABLE 7.-Linear correlation coefficients between gold, barium, 

copper, molybdenum, lead, and zinc for the West, Main, and East ore bodies at the Carlin gold deposit 

West ore body Main ore body East ore body 

Element pair Correlation Element pair Correlation Element pair coefficient coefficient Correlation 

coefficient 

Ph to Cu ______ 0.56 Au to Cu ______ 0.27 Ph to Ba ________ 0.27 Zn to Ph ________ .49 Zn to Ba ________ ,l7 Au to Zn __________ .26 Zn to Cu ________ .40 Mo to Cu ______ ,16 Ph to Cu __________ .l8 Zn to Mo ______ .31 Ph to Cu ______ -.15 Mo to Cu ________ ,17 

Cu to Mo ______ .28 Ph to Mo ______ -.14 Au to Mo ________ .16 Zn to Ba ________ .28 Au to Zn ________ .l2 Au to Cu ________ ,15 

Cu to Ba -------.23 Zn to Ph ________ .11 Zn to Ph __________ .09 

Au to Zn -------.20 Zn to Cu ________ .lO Zn to Cu __________ ,06 

Au to Ba ______ -.17 Mo to Ba ______ -.09 Ph to Mo ________ .05 

Au to Mo ____ -.15 Au to Ph ______ -.08 Zn to Mo ________ -.03 

Ph to Au ______ -.14 Zn to Mo ______ .07 Zn to Ba ________ -.02 

Au to Cu ______ ,13 Cu to Ba ______ -.05 Au to Ba ________ -.01 

Ph to Ba ________ .lO Au to Ba ______ -.04 Au to Ph __________ .oo 

Ph to Mo ______ -.09 Au to Mo ______ ,03 Cu to Ba __________ .OO Mo to Ba ______ -.07 Ph to Ba ________ ,Ol Mo to Ba ________ ,00 
18 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

arsenic-antimony sulfide stage; and the West ore body · marized subsequently. The figures are percentages of 

has a much lower and more uniform content of organic samples taken from the vertically listed ore bodies 

carbon, creating simpler overall geochemical conditions whose mean values are closest to the mean of the 

as described in the preceding section. horizontally listed ore bodies with each step also 

The correlation between gold and barium as deter- involving the variables in the preceding step(s). 

mined for the entire deposit and also for each separate Step 1, copper: 

ore body was the only consistently negative value; this 

fact indicates that the amount of gold in the ore is 

inversely correlated with the content of barium. Barite 

East ---------------- Main _______________ _ 

VVest _______________ _ 

East 

75.38 

43.05 

32.5 

Main 

13.85 

33.33 

10.0 

West 

10.77 

23.61 

57.5 

veins generally contain no detectable amounts of gold, Step 2, barium and copper: 

and the correlations show that within the mineralized East Main West 

carbonate rocks the areas of higher gold content would 

contain the smallest amounts of barite. All these facts 

further support the idea that most of the barite formed 

during a different stage in the paragenesis from the 

deposition of gold. 

The least-squares predictor equation for the average 

gold content over the entire deposit with the independent variables in parts per million is: 

E(Au) =3. 79151-0.00002(Ba)+0.09556 (Cu) 

+0.03908 (Mo)+0.00529 (Pb)+0.0029 (Zn). 

The percent reduction in variance from this linear 

model using only zinc values is 3.99 percent; using zinc 

and copper values 6.31 percent; zinc, copper and lead 

values 6.62 percent; zinc, copper, lead and barium 

values 6.81 percent; and for the full model6.88 percent. 

Thus, the copper values improve the prediction using 

only zinc by 2.32 percent, the lead values reduce the 

variance by only an additional 0.31 percent, barium by 

0.19 percent, and molybdenum by 0.07 percent. The 

standard error of prediction of this equation is± 9. 7 ppm 

gold. 

Statistical analyses carried out to predict the mean 

gold value in each individual ore body using these four 

base metals and barium gave only slightly better 

reductions in variance. These values are for the West 

ore body 8.20 percent, the Main ore body 8. 75 percent, 

·and the East ore body 11.09 percent. 

The multiple correlation coefficients of these elements are: 

West ore body Main ore body East ore body 

Ba:0.43 Mo:0.30 Ba:0.33 

Mo:0.43 Ba:0.29 Pb:0.33 

Pb:0.35 Pb:0.29 Cu:0.33 

Cu:0.30 Zn:0.29 Mo:0.31 

East ----------------

Main---------------- VVest _______________ _ 

74.61 

36.11 

30.0 

Step 3, molybdenum, barium and copper: 

East ---------------- Main _______________ _ 

VVest ----------------

East 

60.0 

27.78 

22.5 

13.85 

33.33 

10.0 

Main 

26.92 

40.28 

17.5 

Step 4, ·lead, molybdenum, barium, and copper: 

East ----------------

Main----------------

VVest ----------------

East 

61.54 

25.0 

32.5 

Main 

16.15 

44.44 

12.5 

Step 5, gold, .lead, molybdenum, barium, and copper: 

East ----------------

Main----------------

VVest ----------------

East 

63.85 

22.22 

27.5 

Main 

20.0 

45.83 

15.0 

11.54 

30.55 

60.0 

West 

13.08 

31.94 

60.0 

West 

22.31 

30.56 

55.0 

West 

16.15 

31.95 

57.5 

Step 6, zinc, gold, lead, molybdenum, barium, and copper: 

East Main West 

East ---------------- 63.85 20.0 16.15 

Main________________ 22.22 47.22 30.55 

VVest ---------------- 25.0 15.0 60.0 

Discrimination analysis using all the variables (step 

6 above) shows that values differed less from the mean 

of their own ore body than from those of the other two. 

This result reaffirms the need to analyze the data 

separately for each ore body. Values in the Main ore 

body were very similar to the ore bodies on either side, 

whereas values in the peripheral areas were much more 

polarized towards their own means. These values 

compare with the mean values in the Main ore body 

which "were highest for zinc, lead, molybdenum, and 

copper but lowest for gold: 

STATISTICAL ANALYSIS OF GOLD, BORON, 

TELLURIUM, SELENIUM, AND TUNGSTEN 

Zn:0.20 Cu:0.27 Zn:0.26 Boron and tungsten are present in highly anomalous 

The equally low multiple correlations found for all these concentrations in Carlin ores compared with their 

elements reflect the very limited value they have in normal abundances in carbonate rocks. Tellurium and 

predicting the average gold content. This conclusion is selenium are present in low abundance in both the ores 

consistent with the paragenetic model proposed previ- and the host rocks, although selenium is enriched in 

ously. mineralized rocks. Published data on the abundances of 

The distribution and relations of these six elements these four elements in primary unoxidized Carlin ores, 

between the three ore bodies were compared by stepwise the fresh carbonate host rocks, together with other 

discriminant analysis. The values found are sum- average values in carbonate rocks are given in table 8. 
STATISTICAL ANALYSIS OF GOLD, BORON, TELLURIUM, SELENIUM, AND TUNGSTEN 19 

TABLE 8.-A bundance of gold, boron, tellurium, selenium, and 

tungsten in fresh limestones and unmineralized carbonate host rocks 

and unoxidized gold ores at the Carlin deposit 

[All values in parts per million. N, not determined or not given; 

X, order of magnitude estimate) 

TABLE 9.-Mean values and standard deviations for gold, boron, 

tellurium, selenium, and tungsten in the West, Main, and East ore bodies at the Carlin gold deposit 

[All values in parts per million] 

West ore body Main ore body East ore body 

Carbonate host rocks Mineralized carbonate rocks Element 

Element Fresh carbo- Fresh carbo- Carlin deposita Carlin deposit4 

nate rocks' nate rocks2 

Average Average Average Median Average Median 

Au------ o.oox 0.005-0.009 <0.02 <0.02 11 10 

B 20 12±8 15 15 70 70 

Te ------ N N <.2 <.2 <.2 <.2 

Se ------ 0.08 0.1-1? <1 <1 2 N 

w ------ 0.6 0.5? N N 18 N 

'Abundance in carbonate rocks in the Earth's crust (Turekian and Wedepohl, 1961). 2Abundance in carbonate rocks (Graf, 1960). 

avalues for fresh unmineralized Roberts Mountains Formation (Radtke and others, 1972; 

Radtke, unpublished data). 4Valucs for unoxidized mineralized Roberts Mountains Formation (Radtke and others, 

1972; Radtke, unpublished data). 

Data used to establish correlations between gold, 

boron, tellurium, selenium, and tungsten come from 

analyses of 288 composite samples selected from 94 

rotary drill holes in unoxidized mineralized carbonate 

rocks. The data were treated statistically by stepwise 

linear-regression analyses to examine correlations 

throughout the entire deposit as well as within each 

individual ore body. Stepwise discriminant analysis 

was also used to compare the mean values of the 

elements between the three ore bodies. 

The data, in parts per million, averaged over the 

entire deposit have the following characteristics: 

Element Mean 

a Au ______________________ -------------------- 79 7.4 

Te -------------------- .02 

Se -------------------- 1.5 

w --------------------- 12 

Standard deviation 

10 

53 

.08 

2.3 

44 

With the exception of gold, as discussed earlier, the 

mean values for the elements correspond well to those 

given in table 8. Values for selenium of 1.5 ppm and 

tungsten of 12 ppm probably are better than queried 

values for these elements reported by Radtke, Heropoulos, Fabbi, Scheiner, and Essington (1972), and 

the tellurium value of 0.02 ppm refines the figure of 

<0.2 ppm given in table 8. 

Linear correlation coefficients between these five 

elements for the entire deposit are, in descending order: 

(1) Au to Te:0.37 (6) Au to W:0.03 

(2) B to Te:0.08 (7) B to Se:0.02 

(3) W to Te: -0.07 (8) Au to B: -0.02 

(4) W to Se:0.04 (9) B to W:0.01 

(5) Au to Se: -0.04 (10) Se toTe: -0.01 

Among all these pairs of elements, only the ratio of gold 

to tellurium is significant and even that correlation is 

much weaker than many others in the Carlin deposit. 

The very low correlations reflect the fact that the data fit 

Mean Standard Mean Standard Mean Standard. 

deviation deviation deviation 

Au------------ 8.8 9.8 6.9 9.0 7.2 10 

B ------------ 54 17 85 55 84 56 

Te ------------ .0 .0 .04 .1 .02 .07 

Se ------------ 1.5 1. 7 .9 2.2 1.8 2.5 

w ------------ 9.7 9.9 17 43 10 50 

a linear model poorly: 

E(Au) =6. 76239 -0.00808(B) 

+46.84856(Te)-0.15657(Se)+0.01276(W) 

when the standard error of estimate is ±9.4 ppm gold. 

The percent reduction in variance due to this function is 

only 13.95 percent with tellurium providing 95.63 

percent of this reduction. 

Correlations between these five elements were 

assessed within each of the three ore bodies. Mean 

values and standard deviations for each element within 

each ore body are shown in table 9, and linear 

correlation coefficients for element pairs for the three 

ore bodies are given in table 10. 

Examination of the correlation coefficients within 

each individual ore body shows that the only significant 

correlation is between gold and tellurium and that this 

is strongest in the East ore body and becomes progressively weaker through the Main and West ore bodies. 

Detailed electron microprobe studies and spectrographic analysis of mineral separates show that 

tungsten occurs in small discrete grains of scheelite, 

and boron is concentrated in clay minerals. The form of 

the tellurium and selenium has not been established. 

We believe that small amounts of these elements could 

be present in hydrothermal pyrite or could occur 

together with the gold, mercury, arsenic, and antimony 

coatings on surfaces of pyrite grains. 

Multiple correlation coefficients for boron, tellurium, 

TABLE 10.-Linear correlation coefficients between gold, boron, 

tellurium, selenium, and tungsten for the West Main, and East ore bodies at the Carlin gold deposit 

West ore body Main ore body East ore body 

Correlation Correlation Correlation 

Element pair coefficient Element pair coefficient Element pair coefficient 

Au to B ______ 0.25 

Au to Se ______ -.15 

W to Se ______ -.13 

Se to B ______ -.12 

Au toW ______ -.04 

w to a________ .02 W toTe ______ .0 

Se to Te ______ .0 

Au toTe______ .0 B toTe ______ .0 

Au toTe ______ 0.34 

Au to Se ______ -.13 

Au to B ______ .09 W toTe ______ -.09 

W to Se ______ -.09 

Se toTe ______ .08 

Au toW ------ .08 B toW------- .06 B toTe .03 

B to Se ------ .02 

Au toTe------ 0.50 

W to Se ______ .12 W toTe ______ -.07 

B toTe ------ .06 

Au to B ______ -.06 

Se toTe ______ -.06 

B to Se ______ .04 

B toW-------- .04 

Au toW ______ .02 

Au to Se ______ .02 
20 STATISTICAL STUDY OF TRACE ELEMENTS, GEOLOGY AND GENESIS, CARLIN GOLD DEPOSIT 

selenium, and tungsten in each ore body are: 

West ore body 

W:0.29 

Se:0.28 

B:0.25 

Te; ___ _ 

Main ore body 

B:0.39 

W:0.38 

Se:0.37 

Te:0.33 

East ore body 

Se:0.51 

W:0.51 

B:0.51 

Te:0.50 

Although the multiple correlation coefficients are 

stronger in the East ore body than in the West and 

Main ore bodies, they are too low to be useful in 

predicting the average gold content. 

Results of discriminant analyses performed to 

evaluate the distribution of the five elements 

between the three ore bodies are shown below. The 

values are the percent of samples taken from the 

vertically listed ore bodies that are closest to the 

mean of the horizontally listed ore bodies. 

Step 1, boron: 

East ---------------- Main _______________ _ 

VVest _______________ _ 

Step 2, tellurium and boron: 

East ----------------

Main---------------- VVest _______________ _ 

East 

53.6 

36.11 

35.9 

East 

24.8 

31.94 

0.0 

Step 3, selenium, tellurium, and boron: 

East ---------------- Main _______________ _ 

VVest ----------------

East 

28.8 

12.5 

5.13 

Main 

26.4 

41.67 

0.0 

Main 

14.4 

18.06 

0.0 

Main 

48.0 

63.89 

23.08 

Step 4, gold, selenium, tellurium, and boron: 

East ---------------- Main---------- _____ _ VV est _______________ _ 

East 

24.8 

12.5 

10.26 

Main 

46.4 

65.28 

15.38 

Step 5, tungsten, gold, selenium, tellurium, and boron: 

East Main 

West 

20.0 

22.22 

64.1 

West 

60.8 

50.0 

100.0 

West 

23.2 

23.61 

71.79 

West 

28.8 

22.22 

74.36 

West 

East ---------------- 26.4 41.6 32.0 

Main________________ 12.5 62.5 25.0 

VVest ________________ 10.26 15.38 74.36 

These analyses again showed the West ore body to be 

significantly different from the other two ore bodies; the 

abundances of these elements in samples within the 

West ore body are consistently strongly polarized 

toward the mean values for that ore body. Any cause 

and effect relation between the statistical data and the 

paragenetic sequence can be much better understood 

when more information is available on the forms or 

occurrences of tellurium, selenium, boron, and tungsten 

in these ores. 

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Geochim. et Cosmochim. Acta, v. 5, p. 49-73. 

Akright, R. L., Radtke, A. S., and Grimes, D. J., 1969, Minor elements 

as guides to gold in the Roberts Mountains Formation, Carlin 

gold mine, Eureka County, Nevada, in Canney, F. C., and others, 

eds., Proc. Internat. Geochem. Explor. Symposium, 1968: 

Colorado School of Mines Quart., v. 64, no. 1, p. 49-66. 

Dickson, F. VV., Radtke, A. S., and Rye, R. 0., 1975, Implications ofthe 

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Dickson, F. VV., and Tunnell, George, 1968, Mercury and antimony 

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trGP 0 695-905