Geochemical evaluation of a mineralized fossil hot system, Eureka County, Nevada

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Authors Grahn, Howard Lance

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Link to Item http://hdl.handle.net/10150/192031 GEOCHEMICAL EVALUATION OF A MINERALIZED FOSSIL HOT SPRING SYSTEM, EUREKA COUNTY, NEVADA

by Howard Lance Grahn

A Thesis Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA

1990 STATEMENT BY AUTHOR

This thesis has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.

Brief quotations from this theses are allowable without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgement the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.

SIGNED:

APPROVAL BY THESES DIRECTOR

This thesis has been approved on the date shown below:

//Dr. Spencer R. Titi bate Professor of Geosciences 3 4

DEDICATION

I dedicate this thesis to the memory of Dr. Randy Gresens, friend, geologist, and mentor. His wisdom and easy humor sparked my love of geology which to this day has not faded. I wish to thank Dr. Spencer Titley for support and patience well beyond the call of duty.

I wish to express my deep appreciation to Dr. Chris Eastoe. Without his continued encouragement, and the inspiration of his unfailing personal and academic integrity, this project would never have been completed. Last I want to thank Chevron Resources Company for their generous and unqualified financial and material support. I wish I would have bailed out when they did. 5

TABLE OF CONTENTS

LIST OF ILLUSTRATIONS 8

LIST OF TABLES 9

ABSTRACT 10

CHAPTER 1 INTRODUCTION 11 Purpose of the Study 11 Location 12 Regional Setting 12 Organization of the Study 14

CHAPTER 2 GEOLOGY OF THE WHITE STUDY AREA 16 Introduction 16 History of White Canyon 17 Stratigraphy 19 Ordovician Valmy Formation (0v) 19 Tuf faceous (Tts) 22 Mid-Miocene Volcanic Rocks 22 Old Basaltic Andesite (Tbaj 22 Pyroxene Dacite (Tpd) 23 White Canyon Tuffaceous Sedimentary Rocks 25 Young Basaltic Andesite (Tba 2 ) 25 Late Basalt (Tb) 25 Tertiary/Quaternary Chalcedony Veins 26 Quaternary Landslide (Qls) 27 Quaternary Sinter Terrace 27 Structure 28 Antler Orogeny 28 WNW Set 29 ENE Fault Set 29 Chalcedony Veins 30 Beowawe Hot Spring 32

CHAPTER 3 CHARACTERISTICS OF HOT SPRING GOLD DEPOSITS 36 Known Deposits 37 District 37 Hasbrouck Peak 38 Round Mountain 38 Borealis 40 Cinola 41 Pueblo Viejo 42 Guanajuato 43 Paradise Peak 44 Characteristics of Hot Spring Associated Deposits 45 6

TABLE OF CONTENTS (Continued)

CHAPTER 4 A HOT SPRING MODEL 46 Hot Spring Fluids 46 Fluid Chemistry 46 Temperature 49 Pressure 49 Boiling 50 Geologic Setting 51 Structure 52 Brecciation 53 Mineralogy 53 Alteration 55 Summary 56

CHAPTER 5 SCOPE OF THE PROJECT 57 Project Goals 57 The White Canyon Study 58 Data Base 59 Precious Metal Data 59 Whole Rock Analysis 62 Baseline 64

CHAPTER 6 DISTRIBUTION OF PRECIOUS METALS AND TRACE ELEMENTS 66 Distribution of Gold and Silver 66 Surface Samples 66 Drill Samples 67 Valmy versus Dacite 68 Silver/Gold Ratios 69 Veins 71 Breccias 71 Sulfides 72 Distribution of Base Metals and Trace Elements 72 Base Metals 72 Arsenic - Antimony 74 Thallium 75 Summary 76

CHAPTER 7 ARGILLIC ALTERATION AND MINERALOGY 78 Introduction 78 Methods 78 Clay Mineralogy 79 Kaolinite 80 Smectite 81 Sericite/Illite/Micas 82 Chlorite 82 Other 83 Summary 84 7

TABLE OF CONTENTS (Continued)

CHAPTER 8 ALTERATION PLOTS 86 Introduction 86 Method 86 Ratios 87 Standard Deviations 89 Grant/Gresen Plots 89 Figure Td-1 90 Figure Td-2 93 Figure Td-3 93 Figure Td-4 94 Figure Td-5 97 Figure Td-6 97 Figure 0v-1 100 Figure 0v-2 101 Summary of the Grant/Gresen Plots 104 Mass and Volume Changes 104 Major Element Distribution 105

CHAPTER 9 THE TRANSFER OF MAJOR AND TRACE ELEMENTS 108 Major Element Transfer 108 Silica 109 Aluminum 111 Potassium 112 113 Magnesium 114 Sodium 114 Iron 114 Trace Element Transfer 115 Rubidium - Strontium 115 Chrome 116 Barium 116 Yttrium - Zirconium - Niobium 117 Summary 119

CHAPTER 10 EXPLORATION CRITERIA 121 Exploration Criteria 121 Indications of mineralization 121 Contraindications 122 Exploration Conclusions and Recommendations 124 1983 Exploration Program 124 Exploration Criteria 127

APPENDIX I SURFACE SAMPLE ANALYSES 128

APPENDIX II WC DRILL-HOLE ANALYSES 136

APPENDIX III WHOLE ROCK ANALYSES 143 APPENDIX IV BASELINE SAMPLE ANALYSES 148 8

LIST OF ILLUSTRATIONS

Figure 1-1 White Canyon Location Map 13

Figure 2-1 Stratigraphic Column 20 Figure 2-2 Stereo Projection of Vein Attitudes 31

Figure 2-3 Strain Diagram, Cross-section 32

Figure 4-1 Dynamic, free-flow hot spring system 47

Figure 5-1 Log/Cross-section, WC drill holes 61

Figure 6-1 Ag versus Au 70

Figure 8-1 Grant plot Td-1 91 Figure 8-2 Grant plot Td-2 92

Figure 8-3 Grant plot Td-3 95

Figure 8-4 Grant plot Td-4 96

Figure 8-5 Grant plot Td-5 98

Figure 8-6 Grant plot Td-6 99

Figure 8-7 Grant plot 0v-1 102

Figure 8-8 Grant plot 0v-2 103

Figure 9-1 Gold versus S 1 0 2 110

Figure 9-2 log Zr/Ti versus lithology 118

Plate I Geologic Map of White Canyon Back Cover 9

LIST OF TABLES

Table 2-1 Whole rock analyses, dacites 24

Table 3-1 Summary of hot spring deposits 45

Table 5-1 Analytical methods, limits, precision 63

Table 8-1 Summary of Grant Plots 106 10

ABSTRACT

In 1980, Chevron Resources Company discovered anomalous gold and silver in a massive silica vein set near the Beowawe hot springs, Nevada. Surface exploration revealed low but consistent gold values associated with the chalcedony veins. The veins are hosted by flat-lying Miocene dacites, and structurally juxtaposed fine-grained Ordovician sedimentary rocks of the Valmy Formation. Preliminary analyses of the relict hydrothermal system revealed sparse mineralogy. The system is dominated by quartz, pyrite, and clay minerals; base metal sulfides and fluid inclusions are absent. Analyses of precious metal data reveals that significant mineralization occurs in the wallrock despite sharp vein contacts, lack of brecciation, and apparent lack of alteration. Although elevated values of arsenic do occur, anomalous values of As, Sb, and Ti do not occur outside of mineralized zones, and are not useful as pathfinder elements. In 1983, Chevron drilled seven exploration holes, encountered only weak precious metals, and dropped the property. Analyses of drill cuttings reveal widespread advanced argillic alteration and secondary iron oxides. X- ray analyses of clays indicate the system is dominated by kaolinite with subordinate montmorillonite and illite/sericite. Secondary potassic alteration takes the form of sericite rather than adularia. Higher Ag/Au ratios in the Valmy Formation are likely the result of residual silver in the sedimentary rocks rather than hydrothermal zoning. Base metals, although very weak, indicate zoning trends and are inversely correlative with gold. Major elements shifts are roughly conformable to the fluid mobility of those elements. Si and K are generally enriched; Ca, Mg, Fe, Na, and Mn generally depleted. These metasomatic reactions produced moderate increases in mass and volume ranging from 10% to 30%. Overall, the system is dominated by, 1) pervasive silicification, 2) hydrolytic leaching and the production of argillic alteration products, and 3) a general fluid redistribution of major elements between the two disparate lithologies. 11

CHAPTER 1 INTRODUCTION

In 1980, Chevron Resources Company discovered anomalous gold and silver occurrences in the vicinity of the Beowawe Hot Springs, Nevada. The property was acquired by Chevron, and a systematic sampling program was begun. Low but consistent precious metal values were found to be associated with a prominent chalcedony vein system which cut Miocene volcanic rocks and underlying exposed Ordovician sedimentary formations. Chevron funded this thesis in 1982 to evaluate

geochemically the economic and exploration potential of the system. Seven percussion holes were drilled by Chevron in 1983. Precious metal values were found to be disappointingly low and at that time, Company evaluation of the property ended. In 1985, Chevron dropped the property.

Purpose of the Study Despite the lack of significant mineralization and the withdrawal of Chevron, the preliminary goals of this thesis remained the same: to utilize mineralogy, trace elements, petrography, and fluid inclusions to define as clearly as possible the physicochemical parameters of the system; to 12 speculate on the production (or lack of) precious metals; and to gain useful exploration insight into the nature and potential of such systems.

Location

The mineralized escarpment exposure of this study, named the White Canyon Property by Chevron, lies primarily in sections 9, 10, 15, and 16 of Township 31 North, Range 48 East, in west-central Lander County, Nevada (Figure 1-1,

Plate I). The property lies about 15 Kilometers south of Interstate Highway 80, and is easily reached by auto. Drive south on Nevada State Highway 21, 3.5 kilometers past the small town of Beowawe, then travel northwest on the well maintained gravel road which traverses the Malpais scarp and ends at the "Beowawe ".

Regional Setting

The study area is typical of the Basin and Range physiographic province, in which extensional tectonics has produced northeast trending ranges bounded by high angle faults. Beowawe is located on the northwest margin of the

Shoshone Mountains, a low-lying cuesta formed of mid-Miocene volcanic flows which dip gently to the southeast. The range is truncated on the north by the Humboldt , and on the northwest by the Malpais Rim, an ENE trending high-angle range-front fault. The Shoshone Range marks the western 13

Figure 1-1: Location of the White Canyon Study area. 14 margin of the Carlin gold belt and hosts both the small Fire Creek gold mine and the larger Gold Acres disseminated gold deposit.

The Malpais Fault is the controlling structure of the study area, and through time has been the locus of considerable hydrothermal activity. It is assumed that the

White Canyon chalcedony vein system of this study is the ancient trace of the modern Beowawe thermal system as it migrated along the Malpais structure. In addition to hosting the chalcedony veins, the Malpais Fault controls the circulation of the presently active Beowawe hot springs (see Chap. 2), and localizes other mineralized areas. To the east the fault cross-cuts the Red Devil mercury mine and associated iron oxide and argillic alteration and, near

White Canyon, the fault exposes a large commercial deposit of Ordovician (exhalite) bedded barite.

Organization of the Study

The Beowawe hot spring has been well studied from an economic, geothermal, and chemical standpoint, and is well documented in the literature. However, prior to Chevron's acquisition, the neighboring White Canyon chalcedony veins had not been previously examined. They are studied here as an entity separate from the hot springs, and it is assumed that the physical and chemical environment which produced the mineralized veins is different from conditions which 15 exist today in the spring system. Therefore, this study utilizes a limited amount of the material published on the

Beowawe thermal system, drawing instead on analyses of the vein system itself, on the abundant published material concerning hot springs, 'hot springs type' precious metal deposits, and the connection therein. The study commences in Chapter 2, with an overview of the geology of the White Canyon study area.

Chapter 3 and 4 of this study examine the theoretical basis of a "Hot Spring Gold Deposit". Existing gold deposits with possible hot spring associations are reviewed in Chapter 3. Chapter 4 assesses the theory of transport and of gold in a hot spring environment, and proposes a "hot spring model".

The scope and intent of the investigation of White

Canyon was reoriented to fit within the confines of the data base, as discussed in Chapter 5. Distribution and transfer of major elements, trace elements, and precious metals are discussed in Chapters 6 through 10. 16

CHAPTER 2 GEOLOGY OF THE WHITE CANYON STUDY AREA

Introduction

One kilometer east of the Beowawe sinter terrace the sharply cut walls of White Canyon mark the western edge of the study area (Plate I). A massive pink and white quartz- carbonate vein system commences in the bottom of White Canyon, and in a roughly en echelon fashion follows the Malpais fault east-northeast for a distance of about 1.5 kilometers. At this point the diminishing vein system is lost under a large Quaternary landslide (Qls of Plate I) which marks the eastern boundary of the study area. Within White Canyon, the massive chalcedony veins cut mid-Miocene dacite flows (Tpd) and crop out as prominent resistant structures up to 2 meters wide. As the system trends east, it emerges into exposed Ordovician sedimentary rocks; the veins crop out less commonly, and the system dissipates into small random outcrops of silica or siliceous breccia. To the southeast, high on the scarp slope, vein exposure is lost under overlying basaltic andesite. 17

History of White Canyon

Rocks of the Shoshone Range represent a geologic history from the mid-Paleozoic to the present. Regional geology is reviewed by Nolan et al. (1956), Roberts et al.

(1958), and Gilluly and Gates, (1965). During the Paleozoic, deep-water siliceous accumulated from continental highlands to the east. These deposits are now represented by thick assemblages of siltstones, shales, cherts, quartzites, and minor volcaniclastics and are exposed throughout the central portion of Nevada.

During the Antler Orogeny of late Paleozoic time, these silicious units were thrust eastward over contemporaneous near-shore calcareous units. The siliceous units are termed the "western assemblage" and they now structurally overlie the thick carbonate sections of the lower plate "eastern assemblage". This structural contact, the Roberts Mountain thrust, is exposed over much of north-central Nevada, and is associated with ground preparation and mineralization in many of the large disseminated gold deposits of the region.

The upper plate eastern-assemblage sediments were severely fractured and folded by the trusting, while the lower plate was only gently warped .

The only occurrence of Paleozoic units within the

Northern Shoshone Range is the scarp exposure of upper plate

Ordovician Valmy sedimentary rocks within the White Canyon 18 study area. The lower plate carbonate units do not crop out in the Shoshone Range and were not intercepted in deep drill holes; the underlying carbonate units, however, are assumed to exist at depth. Igneous activity began in the late Paleozoic in Nevada and continued almost until the present. Through the Mesozoic to early Tertiary time, this activity was primarily formation of high silica rocks; during the mid-Miocene, a new phase of mafic to bimodal began. The thick flows of dacite, basaltic andesite, and basalt of the

Shoshone Range represent this compositional shift (Zoback,

1979). Rare alluvial gravels and pyroclastics mark the unconformable contact of the underlying Ordovician sediments and the Miocene volcanic flows. Two hundred meters of dacite and basaltic andesite are exposed on the walls of White Canyon, while the nearby deep Rossi geothermal well penetrated 1200 meters of volcanic rocks.

The last phase of geologic activity was the initiation of Late Miocene basin-and-range faulting which produced numerous high angle faults and created the present terrain of NE trending ranges. Zoback (1979) has suggested that these extensional tectonics might be contemporaneous with the mafic flows of the Malpais cuesta, but this idea is disputed by Struhsacker (1980).

The geologic evolution of the region continues to the present with the accumulation of the Beowawe sinter terrace. 19

Although the active hot spring no longer impinges on White Canyon, it is assumed that the massive quartz vein outcrop and associated argillization at White Canyon are the product of the ancient thermal system during its migration westward along the Malpais range-front fault.

Stratigraphy

Only the Tertiary pyroxene dacite flows (Tpd) and the underlying Ordovician Valmy Formation (0v) have been observed in the study area, but associated overlying volcanic units are briefly described below. The stratigraphic column of Figure 2-1 and some lithologic description is extracted from Struhsacker (1980).

Ordovician Valmy Formation (0v)

The known base of the local stratigraphy is the

Ordovician Valmy Formation. The Valmy Formation is a thick

succession of silicious hemipelagic sediments that occurs commonly throughout northern Nevada. Roberts et al, (1964),

determined that this allochthonous western assemblage

Formation is at least 2400 meters thick in neighboring

Eureka County. Near White Canyon, the deep Rossi well penetrated 1500 m of Valmy Formation without encountering

the basal thrust structure or underlying carbonate units.

The Formation contains chert, quartzite, shale, siltstone, 20

Os Qs - opaline sinter

0 Is Qls - landslide, probably Pleistocene

QTac OTac - alluvium and colluvium

Tg Tg - coarse grovel with Tb and Tba2 cobbles

Tb Tb - diktytaxitic, subophitic basalt flows

Tba Tba2 - subophitic basaltic andesite flows Twc Twc - White Canyon tuf faceous sediments (no Ov clasts)

Tpd Tpd - pyroxene dacite including porphyritic, aphanitic, and vitrophyric flows

Tbai Tba i - subophitic basaltic andesite and basalt flows

vvvvvvvvv.

Figure 2-1 Stratigraphic column for the Beowawe/White Canyon Region (from Struhsacker, 1980).

21 sandstone, bedded barite, and greenstone (including pillow lava). The unit is structurally complex and is commonly found as stacked thrust sheets. Local exposures of the Valmy Formation exhibit common sedimentary features and a coarse-grained habit. It occurs as clean quartzite, silicified pebble conglomerate, shale, bedded chert, and bedded barite. Within the study area the

Formation is more homogeneous and less distinct, being composed of fine-grained shales and siltstone which are commonly silicified and tectonized. Overall, the unit is highly siliceous, averaging 84 weight percent SiO r

Paleozoic shearing and Tertiary faulting have produced common cataclastic textures that obscure stratigraphic relationships and sedimentary features. In hand sample, rocks of the Valmy Formation are usually light gray, very fine-grained and hard. They commonly color red-purple on fine fracture surfaces, and commonly display liesegang banding, indicating solution oxidation of iron. Tectonic breccias are common, usually with clast-supported open space matrix and rare introduced quartz. Valmy rocks are commonly chalky, indicating a rudimentary arkosic nature and the formation of clays from detrital feldspars. In isolated areas, iron oxides stain the Valmy Formation bright red and orange, reflecting recent hydrothermal activity. 22

Tuf faceous Sediment (Tts) Sparse rounded pebbles rarely found on the surface are the only representation of this thin Formation, which marks the unconformity between the Ordovician and Tertiary rocks.

This unit is composed of Valmy Formation clasts, gravel, sand, and silt in a tuf faceous matrix with interlayered tuff beds to 1 meter thick. This unit forms poor outcrop and has not been observed in the study area.

Mid-Miocene Volcanic Rocks The thick volcanic pile capping the Malpais Cuesta is

labeled on old maps as Tertiary basaltic andesite.

Struhsacker (1980) divided this volcanic sequence into a

tuffaceous unit (Twc) and four separate flow units: 600 meters of basaltic andesite (Tbaj; 300 meters of pyroxene

dacite(Tpd); 100 meters of younger basaltic andesite (Tbad;

and 10-30 meters of basalt (Tb). The pyroxene dacite (Tpd)

is the only volcanic unit associated with the hydrothermal event of this study, but all units are reviewed briefly

below.

Old Basaltic Andesite (Tba) This unit is primarily a medium gray pyroxene-bearing

basaltic andesite with minor olivine. Although older than

the dacite, this unit fills a NNW-trending graben associated 23 with the Dunphy Pass fault zone, and is not known to underlie the dacite within the study area.

Pyroxene Dacite (Tpd)

The Tertiary pyroxene dacite is the younger of the two mineralized lithologies within the study area. West of

White Canyon, within the ancient Dunphy Pass Graben, the pyroxene dacite attains a projected thickness of 500 meters; the nearby cliffs of the Malpais scarp expose nearly 300 meters of the layered dacite flows. East of White Canyon, within the study area and outside the margin of the old graben, the dacite reaches thicknesses of 60 meters. Potassium-argon dates from plagioclase phenocrysts near the middle of the dacite section indicate an age of 16.1 + 0.6 m.y. Struhsacker (1980) believed the dacite flows are correlative with, and perhaps identical to, extensive flows to the northeast, mapped as Shoshone Andesite by Spurck

(1960) and Wilson (1960).

At least four dacite flows are exposed in the Malpais cliffs, and they exhibit variable textures. The units are commonly porphyritic or aphanitic, and display spheroidal and platy weathering habits. Porphyritic dacites commonly

contain phenocrysts of plagioclase, clinopyroxene. olivine. magnetite, and apatite (Struhsacker, 1980). Within the study area, the dacite is primarily aphanitic; hand samples are usually fine grained and 24 relatively unaltered, with rare fresh sanidine phenocrysts.

Fresh surfaces are dark gray brown, but the unit is invariably weathered to a rich red brown. Whole rock analyses of five fresh dacite samples (Table 2-1) show Si0 2 contents of 63 to 68 weight % and confirm the samples as iron-rich potassic dacites.

Sample Si02 AL203 CaO MgO Na20 K20 Fe203 MnO

T-9 62.7 13.4 1.84 1.35 3.02 4.86 9.02 0.12 T18-a 64.5 13.7 2.61 0.52 3.52 4.54 8.27 0.10 Td aphan. 62.3 13.94 3.35 0.93 3.45 4.40 8.70 0.15 Td porph. 66.6 13.37 1.9 0.91 3.11 4.68 6.82 0.04 Avg 64.0 13.60 2.43 0.93 3.28 4.62 8.20 0.10 s.d. 1.7 0.23 0.61 0.29 0.21 0.17 0.84 0.04

Sample TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba

T-9 0.88 0.25 <.01 170 260 60 390 50 1740 T18-a 0.37 0.24 <.01 160 310 50 400 30 1700 Td aphan 0.91 0.22 254 296 1700 Td porp 0.78 0.17 169 296 1430 Avg 0.86 0.22 0 165 248 55 346 40 1643 s.d. 0.05 0.03 0 5 51 5 50 10 124

Table 2-1 Whole rock analyses of five unaltered Tertiary pyroxene dacites from the White Canyon.

In outcrop, the rocks show a blocky, platy, or spheroidal weathering pattern. Flow units are generally flat-lying and structurally undisrupted; chaotic jointing and flow patterns of upper White Canyon appear to be primary volcanic features.

White Canyon Tuffaceous Sedimentary Rocks (Twc) 25

This thin unit of tuf faceous sediments locally overlies the pyroxene dacite, but does not occur within the study area. The unit is composed primarily of a buff colored tuffaceous sandstone containing abundant lithic and tuffaceous fragments. The unit is weakly calcareous; fine layering indicates a lacustrine environment.

Young Basaltic Andesite (Tba 2 )

Five to eight basaltic andesite flows unconformably overlie the Tpd or Twc, and cap the Malpais Rim. Individual flows range from 2 to 16 meters in thickness and thin downdip to the south (Struhsacker, 1980). Similar basaltic andesite flows are common in the region, various isotopic dates yield ages from 16.7 to 14.5 m.y. for the flows. The dark gray basaltic andesites are either porphyritic with plagioclase, pyroxene, magnetite, and olivine phenocrysts, or they are aphanitic and vesicular. The basaltic andesite does not occur in the study area.

Late Basalt (Tb)

Thin localized flows of a dark diktytaxitic basalt unconformably overlie portions of the White Canyon tuf faceous sediments. The units date at 16.3 to 16.5 + 0.8 m.y., essentially the same as the young basaltic andesite

(Struhsacker 1980). 26

Tertiary/Quaternary Chalcedony Veins The chalcedony veins vary in size from meter to centimeter scale, and exhibit a wide range of textures. The veins reach their greatest dimensions of 4 meters near the bottom of White Canyon, and diminish in size as one follows the set east. The massive vein sets consist of white, pink, and gray, fine-grained chalcedony and quartz. Veins are commonly banded parallel to the margins with layers of variably colored and textured quartz and chalcedony including rare drusy and open-space quartz, and late, low temperature chalcedony inf ill. Clays and iron oxides are generally absent in the surface veins, and probably have been removed by weathering. Sulfide horizons consisting of sparse fine euhedral pyrite in clear quartz are common in the smaller veins but rare in the larger veins. Only the massive veins in the bottom of White Canyon proper contain coarse crystalline and common relict calcite (and barite?) textures. The largest calcite horizon measures 0.5 meter wide, runs parallel to the main chalcedony vein, and consists of white, gray, brown, and black, coarsely crystalline calcite. Calcite and relict calcite textures are rare or absent in drill cuttings.

Quartz breccias and breccia horizons are common within the veins and generally consist of highly angular vein 27 quartz fragments supported by a chalcedony or cryptocrystalline silica matrix; breccia fragments are commonly resorbed and indistinct within the silica matrix.

Second generation breccias, indicating recurring dynamic brecciation, have been observed, but are rare. Likewise, temporally distinct cross-cutting vein sets have not been observed, and it is assumed that the chalcedony producing event was not highly episodic.

Quaternary Landslide (Qls)

A prominent and well preserved landslide dominates the terrain two miles east of White Canyon and marks the eastern edge of the study area. The upper breakaway portion of this slide produced near-vertical cliffs in the basaltic andesite flows high on the Malpais scarp. The hummocky lobate debris deposit spreads across the floor of Whirlwind and measures well over a kilometer in diameter. No evidence of the chalcedony mineralization of this study occurs in the scarp face of the slump or in the rubble deposits, indicating the eastern limit of the hydrothermal system.

Quaternary Sinter Terrace

The 60 meter high white sinter terrace is a prominent feature which can be seen from Highway 80, 15 kilometers to the north. Much of the sinter is opaline with sparse layering, but commonly the siliceous material is porous and 28 poorly cemented. No precious metals have been detected in the sinter deposits. Although the remaining pools are depositing silica, most of the sinter deposition ceased with the recent destruction of the geysers.

Structure

Three temporally distinct tectonic events have controlled the formation of the Northern Shoshone Range.

The latest event, Basin and Range normal faulting, has been the most significant in establishing the present-day topography of the region as well as localizing hydrothermal activity and associated mineralization. Plate I shows the dominant ENE and WNW structures as delineated by Osterling

(1960) and Zoback (1979), and mapped by Struhsacker (1980).

Antler Orogeny This late-Paleozoic tectonic event, as evidenced regionally by the Roberts Mountain Thrust, is not exposed in the northern Shoshone Range, but is evident in the highly tectonized upper-plate sediments of the Valmy Formation.

Fracturing of the highly siliceous units, although long in advance of the Tertiary hydrothermal event, has effected the necessary structural preparation for subsequent mineralization.

WNW Fault Set 29

Geophysics and deep drill holes confirm the formation in the Tertiary of a northwest-trending graben which subsequently filled with basaltic andesite. Satellite imagery reveals an associated lineament which cuts the

Malpais Rim just north of White Canyon and continues NW through the Argenta Rim. This system, named the Dunphy Pass fault zone by Struhsacker (1980), splays out horsetail- fashion where it intersects the Malpais fault and forms an orthogonal set of cross-faults that cut the Rim in the area of White Canyon. This fault set forms the eastern graben margin, and displacement is west side down. Thus Miocene volcanic units have been downdropped in the west, adjacent to Ordovician strata that are exposed in the eastern portion of the study area. The Dunphy Pass fault group predates the

Malpais range-front fault and does not offset the chalcedony vein set. Faulting is thought to have continued until the cessation of volcanism at about 10 Ma.

ENE Fault Set Late Miocene Basin and Range extensional tectonics have produced the present day set of northeast trending mountain ranges. Range-front faulting trending N 50 ° E to N 70 ° E delineates the northwest margins of both the Argenta and

Malpais cuestas. Both of these fault blocks have been rotated to the southeast, and the flat-lying volcanic rocks 30 dip gently under the basin gravels at an angle of 5 to 7 degrees. The Malpais range-front scarp dips at angles as steep as 65 0 to the northwest; the maximum vertical slip is estimated by Zoback (1979) to be 500 to 600 meters. In the area of the geysers, the Malpais fault flexes to the east and in the immediate study area the fault trends N

80 0 E to N 85 0 E, generally parallel to the vein set. Parallel and antithetic high-angle faults located just basinward of the Malpais trace have been inferred from geophysical and drill-log data. Flexure of the Malpais fault has produced a subsidiary set of roughly en echelon normal faults which bound the thermal spring activity on both the northwest and the southeast. Although the Malpais fault is considered to be the primary conduit for the thermal system, these short cross-faults focus the thermal activity (Zoback, 1979).

Chalcedony Veins Although the largest of the chalcedony veins strikes

N8094, the stereo projection of vein attitudes (Figure 2-2) shows a more general east-west to northeast attitude of the veins, thus orienting them roughly subparallel to the

Malpais fault. Although the veins are considered by Zoback and Struhsacker to be the result of separate structural events, the close association of these veins to the Malpais 31 fault zone allows reasonable speculation that they formed in response to the high angle faulting. Regional tension is clearly responsible for the block faulting of the Malpais

Rim, but localized normal stresses within the fault trace could result in gash fractures of subparallel and antithetic orientation, as illustrated in Figure 2-3.

Figure 2-2 (1) Malpais Fault Stereo projection of White Canyon vein attitudes. 32

0v

Figure 2-3 Strain diagram and cross section of Malpais range-front fault.

No truncation or offset of the chalcedony veins is revealed across any of the major fault lines, and it is assumed that the vein set post-dates all cross faults.

Beowawe Hot Spring Although this study does not investigate the present day geothermal activity of the region, Beowawe has been well 33 studied and the information is summarized below. Zoback

(1979) presented this brief history of the modern Beowawe thermal springs:

Once a site of many beautiful small geysers, the

Beowawe spring terrace was disturbed by excavation and drilling by commercial power interests in the early

1960's and nearly all natural activity was destroyed. Only three small geysers, numerous

, and a few hot springs are the natural remnants of this commercial activity. Two uncapped

geothermal wells vent continuously into the atmosphere playing to heights of 15-25 m. These wells

have received the misnomer of the 'Beowawe Geysers.'

Now, these wells too have been capped, so only the excavated sinter terrace and a few small pools await the tourists who follow the signs to the "Geysers."

Chevron Resources, Getty Oil Co. and Power Co. have all conducted geothermal exploration in the region, and most of their data have been made available for research through the Department of Energy. This material includes profiles from three deep (1500-3000 m) wells drilled by

Chevron, and forty shallow (150 m) thermal gradient holes.

This data base has resulted in a comprehensive compilation of heat flow, hydrologic, structural, trace element, and 34 alteration studies for the Beowawe Hot Springs.

The Beowawe Company, a joint venture between Chevron Geothermal Company and Crescent Valley Energy Company, is developing the geothermal resource of the area, and at present operates a 15 megawatt dual-flash electrical generating plant on the site. The full geothermal capacity of the system is estimated at 200 megawatts (Struhsacker, 1986).

The area was first investigated as a geothermal site in

1932 by T. B. Nolen and G. H. Anderson, and in 1979 Stanford

University conducted seismic and potential surveys to assess geothermal reservoir potential (Zoback, 1979). The Earth

Science Laboratory of the University of Utah has conducted numerous studies of the area, and their geological overview by Struhsacker (1980) is the most comprehensive reference for the area. Smith (1980) delineated the resistivity of the area, and Christensen (1980) presented trace element data from the shallow wells. In 1980 Iovenitti compared the various hot and cold waters of the valley using piper diagram analyses. Rimstidt (1983) assessed the formation of the sinter deposit, and Sibbett (1983) and Cole et al.

(1984) examined the hydrothermal alteration on the surface and in the deep wells.

Beowawe is a structurally controlled, water-dominated hydrothermal system. The waters are slightly alkaline, sodium-bicarbonate-sulfate solutions which contain very low 35 total dissolved . It is one of the hottest geothermal sites in Nevada. Surface temperatures measure 939C, which is boiling at the 5000' elevation, and reservoir temperatures are calculated to be 215 ct. The waters are meteoric, with recharge coming from the Humboldt to the north (Struhsacker, 1980). Beowawe lies within the Battle Mountain heat-flow high, and it is well accepted that no direct magmatic heat source is recognized to be associated with the geothermal system. The intersection of a mid-Miocene graben structure and younger range front faulting controls and focuses the fluid dynamics of the Beowawe system. In addition, flow breccias and permeable horizons within the volcanic units are thought to affect patterns (Sibbett, 1983). Chemically the waters are anomalously low in all components except silica, suggesting low residence time and low reactivity with the reservoir rock (Christensen, 1980).

Alteration surrounding the thermal system is documented by

Cole (1984) and is, like the White Canyon Study area, dominated by silica and clay formation. Alteration is zoned with depth. From the top it includes zeolites, smectites- zeolitcs, smectite-chlorite and chlorite-epidote. Chris-

tensen (1980) believes the area has been the locus of more

than one geothermal event and that the thermal waters of the past are probably different from those of today. 36

CHAPTER 3 CHARACTERISTICS OF HOT SPRING DEPOSITS

Two basic assumptions dictate the direction of this study. First, it is assumed that the Chalcedony vein set and its associated alteration are the ancient trace of the Beowawe geothermal system which migrated, through time, along the Malpais range-front fault. Secondly, it is assumed that the physical and chemical conditions of that early system are different than those of today. Since the Geothermal system is relatively young, and the stratigraphic successions are relatively intact, this leads to a working premise that conditions which produced the alteration and mineralization of the study area reflect a relatively shallow environment, and are those of a hot spring system. Unfortunately, "Hot Spring" has become a popular descriptor for epithermal gold occurrences and thus has suffered the fate of becoming overused and poorly defined. The association with deep, high-temperature hydrothermal systems is not necessarily clear cut, and it has become common in the literature to read of hydrothermal effects up to plutonic grade included in hot spring discussions. In this chapter a number of deposits are reviewed which have apparent hot spring associations or are considered by 37 other researchers to be hot spring related. In the following chapter, Chapter 5, hydrothermal fluid chemistry is briefly reviewed, and based on the characteristics of the following deposits, a hot spring model is proposed.

Known Deposits

In U.S.C.S. Open File Report tt 82-795, Silberman (pp.

131-143) chose the Sulfur District, Round Mountain, and Hasbrouck Peak, all in Nevada, as characteristic of hot spring type, large tonnage, low-grade ore bodies. These are near-surface low-temperature deposits associated with Tertiary volcanic and subvolcanic rocks. They are localized by major high-angle structures and are characterized by silicification, brecciation, argillic alteration, and limited mineralogy. They may be associated with, or grade into, lode-type vein systems with depth. These three deposits plus others are reviewed below.

Sulfur District In the Sulfur District, low grade precious metals occur in conjunction with sulfotarically altered lacustrine and volcaniclastic sediments. Near-surface boiling has produced an acid-leached and opalized caprock which contains native sulfur and cinnabar. Underlying silicified sediments contain Au, Ag, pyrite and alunite. Argillic alteration is 38 widespread at depth. Mineralization has been dated at 2 Ma from vein alunite, making the Sulfur District one of the youngest intact hot spring precious metal systems known.

Hasbrouck Peak Little published information exists on Hasbrouck Peak, but this system, hosted by Tertiary volcanic rocks and lacustrine sediments and sinters, averages 0.06 oz/T Au and

1.3 oz/T Ag (no reported tonnage). Mineralization is localized by high-angle faulting and occurs with intense silicification, brecciation, quartz veining, and sinters. Alteration grades laterally to argillic or sericitic assemblages with distal propylitic alteration. The deposit is underlain by argillic alteration. Secondary potassium feldspar is commonly associated with quartz veins. It has yet to be determined if either Hasbrouck Peak or the Sulfur District will become economic deposits.

Round Mountain Numerous studies over the last ten years have resulted in various interpretations of the Round Mountain ore body. Berger and Tingley (1980), Mills (1982), Silberman (1982), and Berger, et al., (1986) all concluded that the deposit is epithermal with hot spring associations. Their conclusions are based on the spatial and genetic association of the deposit with a massive breccia pipe, common banded 39 chalcedony + pyrite within consanguineous hydrofracted epiclastic units, and evidence of explosive brecciation and boiling. Sander (1988), however, stated that the breccia pipe is "conclusively" a sediment filled graben; discounted the presence of sinter; and concluded the deposit formed at a depth of at least 750 meters. Berger and others (1986) recorded alteration which is concentric around the "breccia pipe", and represents the introduction of Si, S, and K. Alteration grades from quartz-sericite-Kspar at the center of the pipe outward to quartz-sericite-chlorite to quartz-chlorite. They believed that a steeply-dipping zone of destructive acid alteration might represent a hydrothermal conduit. Trace elements considered anomalous at Round Mountain include As, Sb, Hg, Ti, F, Sn, and Mo. Ti is especially strong in the hydrothermal breccias, and As and Sb correlate well with precious metal enrichment. The orebody contains more than 200 mT of 0.04 oz/T Au which represents more than

8 million ounces of minable gold. Sander's (1988) exhaustive study of alteration reveals

extensive potassic alteration associated with gold mineralization. It takes the form of secondary alunite and

adularia within preexisting fracture sets. Sander's discounting of the breccia pipe, sinters, and hydrothermal

breccias casts doubt on the hot spring association at Round Mountain. 40

Borealis Borealis is probably the best representative of a true hot spring-type gold deposit hosted by Tertiary volcanic rocks. Miocene andesite flows and Pliocene tuffaceous sediments host 2.1 mT of 0.08 oz/T Au and 0.5 oz/T Ag

(Strachen, 1982). Surficial sinters, explosion craters, multiple generation breccias, and a highly leached acid cap provide evidence of surf icial hot spring activity.

Steep normal faults have localized low-grade disseminated gold in near surface silica-flooded breccias and sinters, and in deep quartz-sulfide breccias. "Spring vent bodies" contain small pods of high-grade ore and present good evidence for hot spring activity. The main orebody is overlain by barren supergene-leached quartz breccia. Ore deposition is thought to be a result of repeated brecciation and hydrothermal cratering with contemporaneous quartz and sulfide deposition.

Alteration is zoned in fluid conduits, and grades from quartz-alunite-pyrite outward to kaolinite-montmorillonite- pyrite to chlorite-calcite-pyrite. The deep quartz-sulfide breccia of the main orebody contains two oxide alteration assemblages: (1) quartz-barite- associated with intensely oxidized, high-grade ore; and (2) montmorillonite- hematite- peripheral to the orebody and containing low- grade ore. 41

Cinola

The Cinola deposit of Queen Charlotte Island, British

Columbia, contains disseminated and stockwork gold mineralization hosted by volcanic conglomerates and fine- grained sediments. Mineralization is confined to the hanging wall of the Sandspit fault, and is spatially associated with felsic intrusions and intense silica flooding (Cruson, et al., 1981; Limback, et al., 1980).

Gold horizons grading to 0.25 oz/T occur in a "pumice breccia" and a quartz breccia associated with a subvolcanic rhyolite porphyry. Mineralization is dominated by pyrite, marcasite, and quartz; silicification grades outward to argillic alteration. Trace amounts of Hg, As, and Sb are associated with mineralization.

Richards, et al., (1976) have described Cinola as

Carlin type deposit because of the disseminated nature of the gold and the fine-grained sedimentary host. Cinola geologists (Cruson et al., 1981) suggested that the ore body is more typical of Pueblo Viejo because of the highly- oxidized alteration and the stockwork nature of much of the mineralization. Nelson (1983) proposed that the rhyolite and pumice breccia of Cruson and others (1981) are actually intense silica replacement and silica flooding of sediments, breccias, and sinters. Nelson considers Cinola to be an example of a structurally localized surf icial hot spring deposit. 42

Pueblo Viejo In the Pueblo Viejo deposit of the Dominican Republic, Au and Ag occur in quartz-pyrite-sphalerite veinlets hosted by carbonaceous sediments and volcanic conglomerates

(Kesler, et al., 1981; McCurdy, et al., 1984). The orebody takes the shape of a funnel outlined by deep alunite and shallow pyrophyllite alteration. Outside the mineralized funnel, alteration decreases to a low-grade assemblage of calcite, chlorite, albite, and epidote. Calcite defines the limits of the funnel as well as the ore. Massive jasperoid caps much of the orebody; local surficial kaolinite is considered supergene. Au, Ag, Cu, Zn, Pb, As, Sb, Hg, Te, and Se are all enriched in the oxidized ore zone; Hg, Te, and As are considered by McCurdy and others (1984) to be the best pathfinders. Fluid inclusions indicate that mineralizing fluids were dilute, had temperatures of 130 °C to 2600, and had boiled. The deposit consists of 27 mT of 4.2g/T Au and 21.6g/T

Ag. The 5:1 Ag:Au ratio decreases with depth, reflecting the association of Au with Te and As at shallow levels and its combination in electrum at depth. The orebody is folded and deformed, but no major structures are associated with the system. Kesler (1981) proposed that the deposit is an analog to the Wairakei Hot Spring system in which ground 43 preparation results from hydraulic fracturing, and precious and base metals are precipitated by ascending fluids.

Guanajuato The Guanajuato deposit of Mexico is another example of

an epithermal district which produced high-grade vein deposits as well as bulk minable disseminated Ag and Au. Buchanan (1980) described Guanajuato and proposed that the

deposit is a fossil analog to a modern geothermal system. The district is localized by the Veta Madre fault system and cuts black shale, conglomerates, and tuffs. Quartz-calcite-adularia veins and ore shoots cut all lithologies, and stratigraphy does not seem to affect vein mineralization. Stockwork ore bodies containing large tonnages of low-grade ore occur irregularly in both the

hanging wall and the foot wall of the Veta Madre. Propylitic alteration is widespread in the district;

potassic alteration is abundant and is spatially associated with fractures and veins. Although argillic alteration -- defined by kaolinite and montmorillonite -- is sparse, it forms low pH alteration envelopes around ore bodies. Fluid Inclusions indicate that below the zone of boiling, fluids were hotter and more saline and result in base metal-rich

ores. Above the zone of boiling, the ores are a sulfur-poor

assemblage containing Ag and Au. Such zoning could result from separate dissimilar fluids, but Buchanan suggests that 44 boiling is the major control of metal precipitation at Guanajuato and produces the observed argillic/phyllic alteration assemblage as well as the vertical precious metal/base metal zoning.

Paradise Peak

Paradise Peak, Nevada, is a recent low-grade gold- silver discovery which is described as having a hot spring association (Whittemore and Thomason, 1986). Tertiary andesite and rhyolite tuffs host a thick planar horizon of silica replacement opalite which averages more than 2 ppm

Au. Silica-rich surficial breccias contain 0.25 oz/T Au and

1.9 oz/T Ag. Mineralization is associated with intense silicification surrounded by argillic alteration. The system is underlain by illite and pyrite alteration which is barren of precious metals. Gangue mineralogy is dominated by quartz, pyrite, and marcasite. Gold is found in the native form while Ag occurs as cerargyrite and acanthite. Accessory minerals include chalcopyrite, galena, pyrrhotite and sphalerite.

Siliceous surficial breccias, low temperature and pressure conditions, multiple-generation quartz, and hypogene argillic alteration all are considered indications of hot spring activity at Paradise Peak. 4 5

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CHAPTER 4 A HOT SPRING MODEL

A hot spring is defined as a surface emanation of thermal waters and thus any associated ore deposits must be near-surface phenomena. Such a definition constrains the physical parameters of such a system, and provides a framework on which to construct a workable model.

Hot Spring Fluids

This study addresses a hot spring as a "dynamic flow system" as presented by Yeamans (1983) and illustrated in

Figure 4-1. Such a system is open, free flowing, and structurally controlled. Circulation may reach depths of 3 to 5 kilometers and waters are heated by steep local geothermal gradients rather than magmatic association. Reservoir temperatures seldom exceed 3009,0, and surface waters at 60 3 to 10090.

Fluid Chemistry Hot spring waters are meteoric, relatively dilute, and without magmatic input. Silica is abundant if not 47

Recharge Zone Alluvial system

Depth of circulation 3000 Magmatic contribution ? ? ? JAM 5/83

Figure 4-1 Cross section of a dynamic free-flow hot spring system from Yeamans, 1983. Used with permission of the author. saturated. Sulfur levels are low, as is chlorine; hot springs are not saline systems. pH values are neutral to low, and are seldom alkaline; CO, levels can vary widely, from nil to saturation. Arsenic, Sb, Hg, and Tl can be carried, but rarely in large amounts. 48

Estimates vary widely as to the amount of metal that must be carried in solution to produce viable ore deposits. Present-day active systems suggest that dilute solutions are adequate. At the Broadlands, , and Steamboat Springs, Nevada, very dilute waters appear to be precipitating high grade material. At Broadlands, .04 ppb Au in solution is producing 85 ppm Au precipitates (Weissberg, 1969). Gold is below detection in the waters of

Steamboat Springs, but reaches 15 ppm in surface muds (White, 1981). It is commonly accepted that weak solutions precipitating over a lifespan of 10 3 to 10 6 years could easily provide economic quantities of ore (Weissberg, 1969; White, 1981; Helgeson, 1968), but the nature of known gold deposits does not completely support this idea. Neither Broadlands nor Steamboat Springs contain any significant economic accumulation of precious metals. In addition, known gold deposits suggest a more episodic, or at least periodic deposition, resulting in small accumulations of highly concentrated metals. In almost every structurally controlled hydrothermal ore system, enriched ore zones exist within massive gangue, strongly suggesting that pulses in the concentration of metal cations in solution, or rapid fluctuations in the physicochemical parameters of the system, or, most likely, combinations of both, produce such 49 deposits.

Temperature

Most modern geothermal reservoirs do not exceed 250 0 C

(Ellis, 1979), and this can be construed as a reasonable maximum temperature for associated mineralizing solutions.

Fluid inclusion data support this assumption with known deposits falling well within the epithermal range. Boiling, self-sealing, explosive activity, and fluid mixing all produce temperature permutations, but in general, circulating hydrothermal fluids cool as they rise. Such cooling fluids precipitate abundant silica, but are not an important factor in base and precious metal deposition.

Pressure Shallow depth implies low pressure conditions. More important than absolute pressure, however, is the nature of the pressure gradient and the degree to which fluid pressure exceeds hydrostatic pressure. Retrograde boiling resulting from rapid system-wide pressure fluctuations can severely alter fluid chemistry and mineral solubilities. In addition, explosive boiling or hydraulic fracturing of overpressured systems is a primary mechanism for ground preparation. Pressure regimes and boiling are discussed by

Hedenquist and Henly (1985), Bonham and Giles (1983), and 50

Nelson (1982). The effects of boiling on metal solubility and precipitation are discussed below.

Boiling Boiling of hydrothermal fluids has long been associated with epithermal ore deposits (Phillips, 1973; Cunningham,

1978; Buchanan, 1981; Henley and Ellis, 1983), and has

recently been presented as a major mechanism in localizing

ore (Drummond, 1981; Romberger, 1984; Drummond and Ohmoto,

1985). Abundant evidence exists for boiling in ore

deposits, and modern hot spring systems are known to boil explosively.

Boiling in hot spring environments is commonly

retrograde rather than phreatic or magmatically induced.

That is, boiling is a function of pressure rather than

temperature. In an open free-flowing system, fluid pressure will always be close to hydrostatic, that of the overlying water column. If the system seals, fluid pressure will

approach the lithostatic pressure of the confining wallrock.

Such sealing and over pressuring is well documented and

occurs as a result of quartz, calcite, and other epigenetic

mineralization filling pore and fracture space (Keith et

al., 1978; Muffler et al., 1971; Nairn et al., 1980). At

some critical point, if fluid pressure exceeds the confining pressure plus the tensile strength of the rocks, the system will fail by fracture propagation in a more or less violent 51

fashion, depending on the amount of overpressure. If the

fluids throughout the water column are at their boiling point, the pressure reduction will trigger the formation of a vapor phase, and the fluids will boil. The primary effect of boiling is the partitioning of volatile species into the vapor phase. CO r CH e and H 2S preferentially enter the vapor, while the liquid becomes enriched in halides, bicarbonate, and sulfates.

Partitioning of reduced species into the vapor phase results

in oxidation of the residual fluid. Pumping HS into the vapor phase decreases sulfur concentrations and creates conditions of acid leaching and phyllosilicate stability. Sudden fluid oxidation and the decrease of sulfur species destabilizes metal complexes and promotes the precipitation of precious metals.

Geologic Setting

Hot springs result from meteoric convection in areas of high crustal heat flow, such as regions of thin crust (e.g.

Nevada, Yellowstone) or regions of recent volcanism (e.g.

New Zealand, ). Review of the ore systems presented in

Chapter 3 suggests that our discussion is limited to hydrothermal regimes associated with felsic to intermediate 52 grade volcanic terranes. In addition to furnishing thermal energy, these volcanic units are able to provide a source of low-grade metals for leaching. Tilling et al., (1973), Saeger et al. (1982), and other researchers agreed that source rocks need not be enriched in gold, and that igneous rocks with normal clarke values of 5 ppb or less can provide significant quantities of metal over time.

Structure Structural control is inherent in the concept of a hot spring system. High-angle faults provide conduits for deep circulation of meteoric waters and essentially all systems are structurally localized. Intense silicification, advanced surficial alteration, or a poorly-consolidated sedimentary host can mask surface evidence of structural control, such as at Paradise Peak and Borealis where structural association has not been demonstrated. Struhsacker (personal communication) proposes that major through-going structures, by nature of their size, are not conducive to precious metal mineralization. She suggests that large structures do not allow sufficient sealing to generate the overpressuring and brecciation necessary for metal precipitation. Structural evidence from

Guanajuato, McLaughlin, and Cinola suggests otherwise, as all three deposits are localized by major throughgoing faults. Hedenquist and Henly (1985) suggested a mechanism 53 by which large structures can seal and overpressure locally, while still allowing fluid throughf low.

Brecciation Primary localization of hot spring systems is always structural, but ground preparation is generally accomplished by brecciation as a result of hydraulic fracturing. Explosive eruptions are common and well documented in both modern and recent fossil systems. Hydrothermal brecciation is ubiquitous in known hot spring deposits, and is characterized by silica-flooded angular clasts; resilicified or multiple-generation breccias; banded chalcedony (implying episodic deposition); brecciation of banded chalcedony;

'' deposits (Nelson, 1982); and 'exploded-puzzle' textures in which the breccia clasts can be fitted back together.

It must be stressed that the significance of brecciation is as an indicator of the violent hydrodynamics which trigger severe physical and chemical fluctuations in ore carrying fluids as well as the evolution of open space.

Explosive multiple generation brecciation and associated boiling is critical for metal deposition and thus is an important exploration criterion.

Mineralogy

Dilute, low-temperature thermal fluids produce deposits 54 of limited mineralogy. Cooling ascending thermal waters precipitate large quantities of silica, thus systems are dominated by various forms of low-temperature quartz.

Calcite can occur as early or late vein horizons, but seldom in great quantity and seldom at depth owing to low pH conditions.

Sulfur contents are low in meteoric hot spring fluids, and sulfide minerals are sparse and generally limited to pyrite and marcasite. Chalcopyrite, galena, sphalerite, cinnabar, stibnite, and native sulfur have been recognized in hot spring systems, but are more commonly absent.

Trace and base element minerals often appear to be zoned with depth. Base metals occur at depth, commonly with

Ag; Au increases above Ag; and Hg, Sb, As, Tl and Te concentrate in shallow portions of the system, either associated with or overlying Au. Ewers and Keays (1977) suggested that zoning of trace elements results not only from cooling, but also from their association with base metal sulfides. At Broadlands, New Zealand, As, Sb, Au and

Tl are associated with pyrite, while Se, Te, Bi and Ag occur with galena, sphalerite, and chalcopyrite. At Pueblo Viejo, precious metal values are very low, with Au cutoffs commonly less than 1 ppm. Gold is combined with Te near the surface and with Ag at depth, thus Ag:Au ratios increase toward deep portions of the system. 55

Alteration Dilute fluids and acid vapors produce a hot spring alteration assemblage typified by the leaching of most major elements, the addition of silica, and a residual increase in

Al. Iron, Mg, and Ca are initially concentrated in the

formation of propylitic minerals, but are leached and essentially removed in more advanced alteration suites.

Silica and K are maintained in potassic assemblages as quartz plus adularia sericite. Advanced leaching by acidic vapors produces Al-rich hydrated argillic suites in which Fe, Mg, the alkali elements, and silica are depleted. Alteration is commonly zoned around hot spring environments. Regional propylitic alteration is uncommon; however, if a system is large or long-running, chloritic minerals can form a halo around a deposit, for example Bodie

and Hasbrouck Peak (Silberman, 1982). Argillic alteration

typified by illite, various smectites, and kaolinite is more

characteristic of hot spring environments and generally encompasses the main body of the system. Advanced argillic

alteration overlies major conduits and steam reservoirs, and

represents acid-leaching of all minerals to residual kaolinite. Phyllic caps produced by low pH sulfidic vapors

commonly overlie paleo-spring systems and are thought by

Nelson (1982) and Buchanan (1980) to be valuable surface

indicators of deeper hot spring mineralization. 56

Summary Hot spring deposits are hosted by intermediate to felsic volcanic rocks. They are produced by structurally controlled meteoric hydrothermal systems temporally associated with the residual heat of these volcanic units, or from regions of high crustal heat flow. These mineralizing systems are characterized by silica flooding and sealing, explosive brecciation, and argillic to advanced argillic alteration produced by hydrogen metasomatism.

Sinters and sulfataric alteration are the best indicators of near-surface thermal activity. Mineralogy is simple, dominated by quartz and pyrite. Mineralization is associated with a typical epithermal suite of trace elements; As, Sb, Hg and Tl are suggested as the most useful pathfinder elements besides gold and silver themselves. 57

CHAPTER 5 SCOPE OF THE PROJECT

Project Goals The original goal of this study was an interpretive geochemical evaluation utilizing secondary mineral assemblages and fluid inclusions to determine physicochemical parameters of the mineralizing system, thus allowing speculation about the nature of and search for related deposit types. Unforseen limitations in the scope of this study resulted from the unexpected homogeneity and weakly mineralized nature of the White Canyon system.

Specifically: - very low gold and silver values led not only to the abandonment of the property as an exploration target, but provides a poor data base for correlation of "mineralizing events"; - examination of 27 polished thin sections revealed no fluid inclusions which could be utilized for temperature or determinations;

- examination of more than 40 polished thin sections reveal no sulfides except sparse pyrite. X-ray as well as X-ray fluorescence analysis confirm the absence of trace or base-metal sulfide species thus prohibiting the 58

temperatures of formation assessment of pH, fOr f s , and through coexisting sulfide pairs;

- absence of sulfide and gangue minerals does not allow textural interpretation of paragenesis; - X-ray diffraction of 118 clay separations provides sparse evidence of phyllosilicate evolution or argillic zoning patterns.

This dearth of significant and useful data resulted in severe reorientation of the project and the reliance on generation of major and trace element data for interpretation of this benign system. Indeed, one of the primary conclusions of this study is an understanding of the passive and homogeneous conditions under which a hot spring system can form and still become "mineralized". The very lack of dynamic textures and secondary mineralization is one of the keys to understanding such systems and may be a primary indication of the lack of economically viable mineralization in shallow epithermal deposits.

The White Canyon Study Generation of whole rock analytical data provides a basis for examination of elemental transfer and the development of secondary minerals within the framework of a hot spring system. The study begins in Chapter 6 with a review of the gold, silver, and base metal values and their 59 distribution within the deposit. Chapter 7 presents a brief review of the X-ray analyses and clay mineralogy of White

Canyon. Chapter 8 examines elemental transfer during the metasomatic process utilizing whole rock data and the methods of Gresen and Grant. Chapter 9 presents a summary of elemental transfer within the White Canyon system and characteristics of the mineralizing process. Finally,

Chapter 10 discusses the economic development of the property and its implications as an exploration target.

Data Base

The data base for this study is large and varied. Eight hundred twenty six samples were collected over a period of three years by various workers, and were analyzed by both atomic absorption and x-ray fluorescence. Final tally reveals a data base of 4097 separate analyses. In order to manage this array, all data was computerized and manipulated in spreadsheet format; data groups are reviewed below.

Precious Metal Data

Analytical values were obtained from two separate sample sets, each set producing a slightly different array of data. The first set consists of 255 rock-chip samples collected from surface outcrop by Chevron employees during the 1982 field season. These samples were analyzed by 60 atomic absorption for Au, Ag, As, and Sb and constituted the data base for determining the sites of the 1983 drill holes.

Seventy two of the samples were analyzed for base metals, 56 for Tl and 9 for W.

The 255 surface samples were not available for examination, therefore, all information used in the data compilation was gleaned from the field notes of various Chevron workers. From the notes, these samples were classified according to various lithologic types. Maximum, minimum, and average values were generated and compared using computer spreadsheet. Interpretation from field notes introduces some uncertainty and overlap into the data set and does not permit reliable interpretation of alteration. However, some mineralization trends emerge from this simple scheme. The second sample set consists of cuttings from the

1983 reverse-circulation drilling program. The seven drill holes produced 478 5-foot-interval samples which were analyzed by Atomic Absorption for Au and Ag only. Unlike the surface samples, drill cuttings were available for examination and were relogged for this study using a 40 X binocular microscope. Interpretation of lithology and alteration is therefore more consistent. A cross-section of the lithology and alteration of the seven drill holes is presented in Figure 5-1.

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lithology: < V

g ii r— S — 1 Ti^.7 r— L 1 1 L.. c=3 g 62

There are, however, drawbacks when using reverse circulation drill chips for interpretation, these are threefold:

1) The small (50 to 100 gram) samples used for logging

and chemical analyses may not characterize the entire

five foot interval. Although careful splits were made

at all stages of sample reduction, these small splits may not be truly representative;

2) Study samples were washed at the time of drilling, therefore all fines and some clays were lost;

3) The fine nature of percussion-generated drill

cuttings (commonly < 1 cm) does not allow interpretation of critical textures. Therefore, within

the drill cutting samples, no classifications were

derived for breccia or vein samples since it is impossible to unequivocally identify these types.

Whole Rock Analysis

Seventy-one 10' drill-hole-interval samples were selected for multi-element whole-rock analysis. Samples were analyzed by XRAL Laboratories of Ontario, Canada, for

17 elements by X-ray fluorescence, and 5 elements by Atomic

Absorption. Table 5-2 reviews the methods and precision of the analyses. Results are reported as major oxides and trace elements; all percentages reported below are weight percent as oxides. 63

TABLE 5-1 Analytical methods, limits, and precision.

SiO Al203 CaO MgO Na20 K20

Method XRF XRF XRF XRF XRF XRF Detect. Limit 0.01 0.01 0.01 0.01 0.01 0.01 (wt)

Std.Dev. 0.25 0.06 0.005 0.04 0.02 0.01 (%)

Fe203 MnO Cr2 03 P205 TiO2 LOI

Method XRF XRF XRF XRF XRF XRF Detect. Limit 0.01 0.01 0.01 0.01 0.01 0.01 (wt)

Std.Dev. 0.03 0.005 0.00 0.00 0.005 0.09 (%)

Nb Rb Sr Y Zr Ba

Method XRF XRF XRF XRF XRF XRF Detect. Limit 10 10 10 10 10 10 (PPm)

Std.Dev. 20 20 10 20 10 40 (PPm)

Au Ag Sb As

Method AA AA AA AA Detect. Limit 0.02 0.1 0.1 0.1 (PPm) 64

Sample intervals were chosen to represent each drill hole, but still give even weighting to mineralized vs. un- mineralized, altered vs. unaltered, and dacite vs. Valmy sections for comparison purposes. Three standards and two duplicate samples were included in the analyses and all values were within acceptable limits. Whole rock analyses are used for simple statistical comparison, for correlation with mineralogical data, and in the plotting of the Grant/Oresen alteration diagrams. For statistical comparison, the whole-rock sample set has been separatedby lithology, mineralization, and degree of alteration. Designations of argillic or advanced argillic alteration are based on pervasiveness of alteration, textural destruction, and abundance of secondary clay products. Breccia and vein classifications are not used; breccias are not always distinct in drill cuttings, and despite common pervasive silicification, no unambiguous large-scale veins were encountered in the drill intervals.

Baseline In order to establish a basis for comparison, a set of hand samples were chosen and analyzed for major and trace elements as well as precious metal content. These 21 samples were selected to be as representative as possible of both fresh and altered phases of the various lithologies, and are used for baseline comparison purposes. 65

Among the dacite baseline samples, control is good and analyses are consistent. Nine of the eleven samples were collected in the field and represent fresh, altered, and highly altered states of the progressively argillized volcanic rocks. Also included in the Baseline data set are two published analyses of fresh dacite, taken from

Strushacker's 1980 study of White Canyon. The fresh dacite analyses are consistent, and fit within the CSM classification as an iron-rich potassic dacite. Finding representative fresh and altered examples of the highly tectonized Ordovician sediments is difficult.

Five Valmy Formation samples were collected to represent "typical unaltered" rocks and two were designated "highly altered" for baseline purposes; control on this group, however, is poor. Wide variability is common throughout all analyses of Valmy Formation rocks and limits interpretation of metasomatic processes. Such scatter probably results from the initial compositional variability of the protolith and is intensified by the long history of tectonism and accompanying metamorphism.

In addition to the dacite and Valmy Formation samples, two chalcedony veins and one Tertiary basaltic andesite sample were analyzed for the baseline group. 66

CHAPTER 6

DISTRIBUTION OF PRECIOUS METALS AND TRACE ELEMENTS

In order to assess precious and base metal distribution in White Canyon, precious metal values from 733 samples and trace and minor element data from 92 samples have been col- lected for analysis and comparison. The sample base was simply divided into classifications based on lithology, alteration, or mineralogy; using a computer for elementary statistics and graphing, the various splits were compared.

In most cases sample populations were large enough for credible results, though in some instances splits were small. Within the limits of such elementary statistics, some interesting comparisons were found.

Distribution of Gold and Silver

Surface Samples

Fifty-three percent of the 255 surface samples contain detectable gold (> 0.02 ppm). For gold-bearing samples, the 67 overall average values are 0.10 ppm Au and 2.57 ppm Ag for an overall Ag:Au ratio of 36. High values are 0.56 ppm Au

(0.016 oz/T) and 43.2 ppm Ag, thus none of the samples approach ore grade. Although the gold values are consistently low in surface samples, the high detection

frequency clearly justified Chevron's initial exploration

effort.

Gold-bearing samples show a significant increase in

arsenic levels compared to barren samples, but show an

inverse correlation with Pb and Zn. Arsenic values increase

1.8 fold in gold bearing samples, while lead increases 2.5 X

and zinc increases 2.9 X in barren samples. Cu, F, and Ti

show no obvious correlations with mineralized or barren

samples.

Drill Samples

Forty-two percent of the 478 5' drill intervals contain

detectable gold (> 0.02 ppm). Maximum values are 0.58 ppm

Au and 10.6 ppm Ag. The 199 mineralized samples averaged

0.12 ppm Au and 1.7 ppm Ag. The best mineralized interval

is 85', averaging 0.24 ppm Au (0.007 oz/T) and 2.1 ppm Ag.

It was on the basis of these poor showings that Chevron

discontinued the project in 1984.

In the drill cuttings, fifty-one percent of the dacite

intervals are mineralized, averaging 0.12 ppm Au and 1.3 ppm

Ag for a Ag:Au ratio of 15. In contrast, only 33% of the 68

Valmy intervals are mineralized, averaging 0.11 ppm Au and

2.2 ppm Ag with an average Ag:Au ratio of 28.

Valmy versus Dacite Overall (combining all sample groups), 48% of the

dacite samples are mineralized (contain detectable Au >

0.02ppm), compared with 36% of the sediments. Average gold

values are 0.12 ppm for the dacite versus 0.09 ppm for the

Valmy. These figures are probably not highly significant

but instead reflect sampling effects and the fact that the mineralized structures are better developed and more visible

in the dacite. Considering only the surface samples, only 36% of the

dacite contain detectable gold; however, these mineralized

volcanic rocks produced the highest single gold value (0.56

ppm) as well as the highest average values at 0.14 ppm Au

and 2.17 ppm Ag. The low percentage of samples with detectable gold reflects the decrease in mineralization away

from veins, however the high average value demonstrates

significant mineralization of wall-rock beyond the vein

margins.

Forty-two percent of the Valmy Formation samples

collected from the surface contain detectable gold averaging

0.06 ppm Au and 2.01 ppm Ag. This increased rate of

detection probably reflects the diffuse nature of alteration

and mineralization in the fractured sediments. The lower Au 69 content results in a higher Ag:Au ratio of 46.

Silver/Gold Ratios

Like gold, silver values are low throughout the system, rarely exceeding 10 ppm. For purposes of calculating ratios, all gold and silver values below detection were eliminated. The sample base thus dropped to 99 mineralized dacite and 86 mineralized sedimentary rocks which produced average Ag/Au ratios of 16.5 and 29.0 respectively. Figure

6-1 displays Ag plotted against gold, with values keyed for lithlogy. The figure clearly shows the higher Ag values in the sedimentary rocks.

Classic epithermal zoning patterns consist of deep base metals with associated but less deep silver, zoning upward to shallow gold enrichment, thus indicating higher mobility for gold than for silver or base metals. Such a system would produce decreasing Ag/Au ratios along with decreasing gold values as one moved away from the heart of the system.

Precious metal distribution at White Canyon does not reflect this pattern, since Ag/Au values increase away from the assumed core of the system.

The Valmy Formation is considered the more distal portion of the system based on the diminishing and diffuse nature of the chalcedony vein system and a paucity of silicification, stockworking, and argillic alteration.

However, the higher overall silver values and resultant high 70

Figure 6-1 Au vs Ag, WC drill samples 71

Ag/Au ratios would suggest otherwise. Either the White

Canyon system is controlled by reverse zoning effects, or, more likely, the sediments contain a higher level of residual background silver than the dacite. Relatively high detection limits on Ag (0.2 ppm) do not allow reliable analysis of Valmy background precious metal levels.

Veins Seventy three percent of the surface samples which are described as "vein material" contain detectable gold averaging 0.11 ppm Au and 3.05 ppm Ag. This high incidence is not surprising as the veins were always assumed to be the ore carrier. What is significant is the low values of gold plus the fact that 27% of the vein samples are barren. It is also interesting that the highest average gold value

(0.12 ppm) occurs not in the veins, but in the dacite grouping. Once again, this represents a significant process of wall-rock enrichment.

The high silver values of the veins give this group the highest Ag/Au ratio of 33. The gold-bearing vein samples show a 4.4 X increase in As values and a 1.8X increase in Sb over non-mineralized samples. Base metals show no obvious trends within vein samples.

Breccias

Sixty-nine surface samples are described in workers 72 field notes as some type of breccia. These samples show a lower than expected incidence of mineralization -- 43% -- and low overall metal values at 0.07 ppm Au and 2.72 ppm Ag. It is not possible from the notes of Chevron geologists to distinguish tectonic, auto-clastic, or hydrothermal breccias.

Sulfides Thirty one percent of the surface samples collected by

Chevron workers were described as sulfide-bearing, usually with pyrite. Primarily these samples were silicified veins or breccias occurring in both the dacite and the Valmy

Formation. Of these sulfide-bearing samples, 73% were mineralized with Au averaging 0.10 ppm and Ag averaging 3.20 ppm. As with the veins, the significance here is that 23% of the pyrite-bearing samples are barren and thus gold precipitation is not strictly coincident with sulfide deposition.

Distribution of Base Metals and Trace Elements

Base Metals

Base metal data are limited by low frequency. However, base metals are essentially nil in the system. In all cases, Cu, Pb, and Zn averaged in the tens of ppm, 73 precluding the existence of discrete base metal phases. Cu averaged 4 - 7 ppm throughout. Pb values were only

slightly higher and seemed to indicate an inverse cor- relation to gold. Zn reached a maximum of 660 ppm in one non-gold-bearing dacite. In the sulfide split, Zn reached a maximum of only 110 ppm, averaging 26 ppm in 32 assays. Zinc showed the strongest inverse correlation to gold, showing higher values in the non-mineralized splits. Clarke values for Cu, Pb, and Zn, in altered dacite are

10, 15, and 65 ppm respectively. To the extent that these

elements show a reverse correlation to precious metals, it is interesting to speculate as to whether the base metals

are depleted from the country rock by mineralizing fluids. Cu averages 5 ppm in all splits, whether gold-bearing or

not, and thus gives no indication of enrichment of depletion. Lead levels are very close to Clarke values for

all surface dacite samples and are, again, equivocal. Zinc levels in Au-bearing dacites are about one half of the

expected Clarke value, 33 ppm versus 65 ppm respectively.

Zn in barren dacites averages 101 ppm; such levels could

indicate depletion of Zn. Base metal values of vein samples show the same reverse correlation to Au as that shown by the

dacite. Pb is roughly 3-fold, and Zn roughly 2-fold

enriched in barren chalcedony compared to those viens which

carry Au. Assuming that all base metals in the vein samples

are added, such mineralization of the veins supports a 74 process of precious-metal/base-metal zoning within the hydrothermal system.

The few Mo and W assays obtained only serve to indicate that no significant quantities exist in the areas sampled.

Arsenic - Antimony As and Sb are easily mobilized by thermal fluids.

Their tendency to accumulate in the upper or vent portions of hydrothermal systems makes them potential pathfinders in geothermal and mineral exploration (Christensen, 1983;

Weissberg et.al., 1979).

At White Canyon As and Sb generally mimic each other and commonly follow mineralization trends. Values range from 2 to 484 ppm As (average 44) and 1 to 20 ppm Sb

(average 4.1). Both elements increase two-fold in the gold- bearing fractions. Dacite samples contain three-fold the

As and twice the Sb as the Valmy samples. Values also tend to increase with increasing alteration; high values occur in the advanced argillic groups. Such concentration might be the result of adsorption by the abundant phyllosilicate alteration products in the dacite, or an effect of the well- developed fluid conduit system associated with the fracture- prone dacite.

Chalcedony veins increased from an average of 13 ppm As in barren samples to 56 ppm in gold-bearing samples.

Breccias show a similar increase of As and Sb with Au 75 mineralization. This indicates that precipitation of these elements is not just a function of brecciation or chalcedony production, but is associated with the deposition process of gold. Of all the splits, only those samples described as

sulfide-bearing indicated no increase in As values with gold mineralization. This indicates that the precipitation of As must be roughly coincident with the deposition of sulfides.

At 70 ppm average, values are relatively high, but are too

low to assume the presence of As-sulfides. This is consistent with the findings of Christensen et.al. (1983)

and Ewers and Keays (1977) that sulfides and hematite after

sulfides are the primary host for adsorbed As and Sb.

Thallium

Fifty-six Ti analyses were obtained from dacite and vein material. Values range from 0.1 to 5.4 ppm, averaging 0.7 ppm overall. Thallium has been proposed as a potential hydrothermal pathfinder element (Nelson, 1983; Massa, 1982), but in this study the small sample base and low values are not definitive. Although all samples are enriched above background levels, trends seem to be random. In the dacite and the sulfide-bearing splits Ti levels decreased in the

gold fractions; in the vein and breccia splits Ti levels

increased with gold, though the vein samples contained the lowest average Ti values (0.5 ppm). 76

Summary

Distribution of gold, silver, and trace elements at

White Canyon reveal the following features:

* significant mineralization of wallrock exist despite the sharp vein contacts and apparent lack of wallrock alteration in surface exposures;

* significant portions of the chalcedony veins are barren indicating episodic mineralization or mineralization processes which are separate from quartz deposition;

* gold values in the chalcedony veins are never high, which might be an important indication of the lack of economic mineralization;

* Au is not strictly coincident with pyrite, thus sulfide deposition is independent of gold deposition;

* As/Sb clearly follow mineralization trends, but are not useful as pathfinder elements since elevated values rarely exist beyond the precious metal mineralization;

* high Ag/Au values in the Valmy Formation seem to indicate primary lithology rather than precious metal zoning;

* it is likely that no base-metal sulfides are present;

* base metal deposition is nil in veins;

* Pb and Zn show strong inverse correlations to Au, 77 probably indicating classic zoning trends;

* Cu, F, Ti show no correlations with precious metals;

* As/Sb deposition is coincident with sulfide occurrence;

* Ti is not useful as a pathfinder in this system; * Au and Ag are the best pathfinder elements in this system. 78

CHAPTER 7 ARGILLIC ALTERATION AND CLAY MINERALOGY

Introduction

The primary effect of the White Canyon hydrothermal system is a redistribution of major and trace elements and the creation of a single new lithology from the previous disparate rock types. Acid leaching of both the volcanics and the siliceous sediments has produced a pervasive system- wide elemental and mineralogical shift toward a norm of phyllosilicate alteration products.

In order to document the production of secondary alteration products, X-ray diffraction was used to delineate sulfide, clay, and feldspar mineralogy. One hundred ninety two X-ray analyses were performed on both whole rock samples and mineral separates in an effort to delineate primary and secondary mineralogy. Clay minerals identified by XRD are shown on WC drill hole logs (Fig. 51, p. 64).

Methods Samples were analyzed with a Siemens D-500 X-ray diffractometer using a copper target. Bulk samples were powdered, spread thinly on a glass slide, and scanned at a 79 rate of 2 ° 2theta/minute, with a power setting of 30 mAmps and 40 kVolts. Minerals were identified using the Powder Diffraction Standards published by the Joint Committee on

Powder Diffraction Standards (1974) and the Table of Key Lines in X-ray Powder Diffraction Patterns of Minerals in

Clays and Associated Rocks, Chen, 1977. Methods and sample preparation are reviewed by Carroll (1970). To prepare clay separates, samples were powdered, blended in water at high speed for 5 minutes, then centrifuged 15 to 30 minutes to separate the various size fractions. The < 4 micron fraction from these samples were analyzed as the clay fraction. In order to distinguish chlorite from kaolinite clay samples were X-rayed, then heated to 600 GC (destroying the 7 Angstrom kaolinite peak), and then X-rayed a second time for comparison. When smectites were suspected in a preliminary X-ray scan, the sample was glycolated; a second X-ray scan then detected the expanded d-spacings indicating a montmorillonite member.

Clay Mineralogy

Structurally and genetically there are three basic clay groups formed in hydrothermal systems: kaolinite; the

smectite group; and illite, which is intermediate between micas and clays. Finally, muscovite, in the form of

sericite, is important as an indicator of secondary 80 potassium-rich alteration. Al]. these minerals are the result of progressive acidic alteration; kaolinite, being pure hydrated aluminum silicate, is the final end product of hydrogen metasomatism and hydrolytic cation leaching. Deer,

Howie, & Zussman (1966) provide a comprehensive review of mineralogical characteristics of the phyllosilicates. A brief review of the mineralogy and the occurrence of clay minerals in White Canyon drill cuttings is presented below.

Kaolinite Kaolinite is the most important member of the kandite group which includes the polymorphs nacrite and dickite, and the hydrated form halloysite. Kaolinite, A1, 1S1 20 5 (OH) 4 , is a pure clay with little atomic substitution or structural variation and thus contains no alkalies or other cations except Al and Si. Under the severe leaching conditions of a low pH system, kaolinite is considered to be the final end product of feldspar deterioration. For this study, kandite group minerals were not differentiated.

At White Canyon, kaolinite is ubiquitous in altered rocks, occurring in 74% of all clay samples analyzed. It is present in argillized dacites as well as in developed clay horizons, and generally (but not always) predominates over smectite. Little zoning evidence exists, but in the few cases where kaolinite does not occur throughout the drill 81 hole, it tends to accumulate in the upper portions. This

effect possibly reflects its genesis within an acid-leaching vapor cap.

Smectite

Unlike kaolinite, the smectite group is subject to unlimited isomorphic cation replacement; it is therefore

difficult to delimit definite species. Common smectite minerals include montmorillonite, sauconite, saponite,

hectorite, and nontronite. In addition to the

stoichiometric substitution of Al, Mg, Fe, Li, and Zn,

smectites are cation scavengers and readily incorporate Na,

Ca, K, Cs, Sr, H, and other elements into their lattice.

Smectites are common weathering products of volcanic rocks,

but are here considered products of incomplete hydrolytic

leaching. All smectites are "swelling clays" that absorb

organic solvents and are thus easily detected by XRD

methods. For this study, individual members of the smectite

group are not identified.

At White Canyon, smectites are common throughout. They

are actually more widespread than kaolinite group minerals

(occurring in 79% of analyses), but are commonly less

abundant than kaolinite. Only drill hole WC-6 contains a

well developed clay horizon which is dominated by smectite.

This zone consists of nearly 200 feet of orange and brown

iron-stained clays which are weakly mineralized with gold. 82

Smectite, along with illite/sericite, dominates this section, with weak kaolinite near the upper portion and weak chlorite in the lower portion. Throughout the rest of the system, smectite occurs generally in association with kaolinite or to a lesser extent with the sericite/illite. To the extent that any zoning exists, smectite dominates the deeper sections of most drill holes.

Sericite/Illite/Micas

Sericite, as the fine-grained secondary version of muscovite, is a common indicator of potassic alteration.

Illite, as a clay-sized mixed-layer mica mineral, is a likely detrital component of Valmy Formation rocks.

Unfortunately, XRD techniques do not readily distinguish between members of the mica groups, which include, along with sericite and illite, biotite, muscovite, and celadonite. These 10 Angstrom minerals occur only sparsely and sporadically in XRD scans of drill cuttings, and are referred to collectively in this report as sericite/illite.

Chlorite

As a secondary alteration mineral, chlorite takes up mobilized Fe and Mg (plus Hp) while releasing more mobile

Si, Ca, and Na from common rock-forming minerals. Along 83 with epidote and/or calcite, chlorite is an indicator of propylitic alteration. X-ray and visual analyses confirm that chlorite is rare in the White Canyon system. Two XRD traces indicate that chlorite exists in a deep silicified portion of drill hole

WC-6, near the bottom of a thick mineralized clay zone. This one indication of propylitic alteration could represent a distal margin of the hydrothermal system.

Other Minerals X-ray diffraction examinations of other mineral groups reveal the following: 1) Strong quartz patterns dominated every X-ray run including sulfide and clay separates; this is likely a reliable indication of pervasive silicification;

2) Orthoclase/sanidine is common, but is considered to be an indication of residual sanidine rather than secondary

K-feldspar occurrence. Potassium staining indicates that secondary K-feldspar is essentially absent in altered rocks;

3) No zeolites were detected in XRD traces. 4) XRD scans of both powdered sulfide concentrates and sulfide-rich polished thin sections failed to detect any sulfide mineral except pyrite. 84

Summary

Pervasiveness of all major clay groups throughout the system, plus the poor XRD resolution of individual clay minerals, has resulted in a limited interpretation of phyllosilicate mineralization. The lack of three dimensional spatial control in drill hole sections also restricts interpretation. For example, the 50+ meter clay horizon of drill hole WC-6 is likely a vertical section, parallel to near-vertical structural conduits, and possibly only meters wide. No evidence is available to indicate the actual orientation or dimension of such occurrences.

In general, kaolinite is pervasive throughout most drill sections, followed by smectite and illite/sericite. Weak zoning indications show kaolinite more common in upper portions of clay horizons with smectite and sparse chlorite in deep portions. This could be interpreted as strong acid leaching in the upper portions of the system, with fluid migration of less complete argillic alteration, preceded by weak propylitic alteration, in deeper portions of the system.

Although clay sections dominated by smectite occur only in the Valmy sedimentary rocks, there is no clear evidence that clay development differs between the two rock types.

Regardless of original lithology, the final result of severe hydrolytic cleaving is the stripping of most major 85 cations and the production of residual hydrated aluminum silicate end-products. Reflecting this depletion and redistribution of major elements, most acidic hydrothermal systems develop a progressive alteration pattern reflected by zoning of classic propylitic, sericitic, and finally argillic alteration types. At White Canyon, chlorite, as an indicator of propylitic alteration, is rare. Sericite and secondary potassium feldspars, as indicators of potassic alteration, are also rare. The only alteration assemblage clearly

associated with the White Canyon system are argillic and/or advanced argillic alteration as evidenced by abundant kaolinite and smectite development. It should be noted that surface exposures at White

Canyon do not reveal the widespread and commonly pervasive argillic alteration which is indicated by drill sections.

It should be assumed that extensive buried argillization can

be masked by the rapid surface weathering of highly altered

rocks, especially in a normal-fault environment of resistant lithology. 86

CHAPTER 8 ALTERATION PLOTS

Introduction

Gresens (1967) pointed out the problems of using fixed stoichiometric equations to estimate elemental gains and losses resulting from metasomatic reactions. He proposed a method by which absolute gains and losses of material could be calculated using analytical values plus changes in specific gravity. Grant (1986) demonstrated that Gresens method can be simplified by graphically plotting analyses of metasomatized rocks against those of their protolith equivalent. Utilizing an assumption of constant mass or volume, or the immobility of certain elements, an isocon (line of equal concentration) can be plotted which shows actual gains and losses of material during alteration. The slope of the isocon indicates the change in mass during alteration, which in turn can be related to volume change using specific gravities.

Methods

Whole rock analyses of samples in various stages of alteration are plotted in the following figures using 87

Grant's method. Samples are always plotted against rocks which are progressively more altered or mineralized. C c) , component of the original rock, is plotted against C A , component of the (more) altered rock. The slope of the isocon relates to the masses of the samples: A o A o C = (M /M ) C

Volume changes are calculated from the mass using the specific gravities (g) of the samples:

g = M/V therefore V A/V ° = MA/Mo golgA

Elements are plotted in the figures without units, as reported in weight percent oxides or as ppm. Most elements are mathematically scaled simply for convenience of

interpretation.

The determination of an isocon is critical to

interpretation of the plot, and is based on an assumption of mass or volume change or the immobility of selected elements. Conditions of advanced alteration at White Canyon

do not remit the assumption of constant mass or volume,

therefore element ratios were examined, as per Gresens

(1967) suggestion, in order to determine if suitably

immobile components might exist.

Ratios

Ratios of elemental abundances were generated by

computer for all samples. Consistency of ratios through 88 various stages of alteration indicates that a pair of elements remain in similar proportion because a) they are chemically immobile or inert and are not enriched or depleted during metasomatism; or b) they are chemically coupled and react in similar fashion, thus are enriched or depleted to the same extent. To guard against "b", it is important to utilize pairs of elements which are geochemically dissimilar.

Among the dacite samples, Si, Fe, Ca, Mg, K, and Na, are highly variable (i.e. mobile within the system), as are the minor elements Rb, Sr, and Y. Chrome and Nb levels are too close to detection limits and are not considered useful.

P and Fe were unexpectedly consistent, but were not used to define isocons. Another unexpected result is the apparent stability of barium which commonly shows consistent values when ratioed with Al, Fe, Zr, and Ti. Aluminum produced consistent ratios against some trace elements, and is considered reliably immobile in the plotting of most isocons. Zr and Ti showed the most consistent ratios through all stages of alteration, and are considered for the purpose of these plots to be relatively immobile. Ti is considered to be the more reliable of the two owing to greater analytical certainty, but both elements

(plus Al) were utilized in the placement of isocons. These two elements are useful not only in the Grant plots, but as a ratio, they are also the most definitive chemical 89

indicator of the Valmy Formation/dacite boundary (Fig. 9-2).

Ratios of all components within the Valmy sedimentary

rocks show wide scatter and inconsistencies and for this

reason the Grant plots of the sedimentary section are considered less reliable. Only two plots of Valmy samples

are presented, and although evidence of immobility is far

less conclusive, isocons were again plotted primarily on the basis of Ti, Zr, and Al.

Standard Deviations All elements are plotted with a two-standard-deviation

range-of-error. Standard deviations are those reported by

XRAL Labs (Table 5-1), and reflect the analytical precision

for each element. This envelope was commonly used to

determine a best-fit isocon on those samples with wide data

scatter. Wide ranges of error for some elements are a

result of scaling or of comparing ppm and wt. % oxide

values.

Orant/Gresens Plots

Figures Td-1 through Td-6 are plotted from dacite

samples collected on the surface and from drill cuttings.

The regional homogeneity of the dacite, plus the

availability of clearly unaltered dacite (protolith)

provides data for generally reliable Orant/Oresens plots. Figures 8-7 and 8-8 are plots of Valmy Formation drill 90 cuttings. These two figures clearly display the uncertainty inherent in the variability of the sedimentary data, but still illustrate some of the mineralizing trends within the sedimentary unit. A summary of data and conclusions from all plots is compiled in Table 8-1.

Figure Td-1

This figure plots the change from an unaltered dacite to a sample described as moderately argillized and without added silica. Reflecting the minor alteration of this fresh dacite, the isocon fit is very good through Si, Al, Ba, and

Ti. The isocon slope indicates that C A = 1.06 C ° representing a mass loss of 6%. The ratio of specific gravities for the two samples is 1.04, and indicates a net volume decrease of 2%.

Deviations from the isocon indicate strong depletions of all mobile major elements except K. Ca, Fe, and Mn are strongly depleted, with lesser amounts of Na and Mg being leached. K shows a 15% increase in the early stages of argillization; this could indicate an early phase of potassic alteration. This plot shows weak agreement between

Zr and Ti, though the selected isocon fits within the error range of Zr. Choice of an isocon with a best-fit between Zr and Ti would indicate a slight enrichment in Si0 2 and Alp v and a small increase in both mass and volume. 91

o1 es

Figure 8-1 Grant/Oresens Plot Td-1 02

— a

T I I I I ' L ' o

Figure 8-2 Grant/Oresens Plot Td-2 93

Figure Td-2

Like Figure Td-1, this plot is produced from surface samples which are not spatially associated. This diagram illustrates the change from unaltered dacite to a state of pervasive advanced argillic alteration. The isocon is chosen as a best-fit and shows good agreement through Al, Ti, Ba, and Zr. The isocon slope is C A = 0.56 C °, indicating a 78% mass increase and an 88% volume increase.

These are the largest mass and volume changes of all the plots, and although apparently extreme, are probably only local and may not be unreasonable in the predominantly tensional regime of normal range-front faults.

This plot indicates a large silica and potassium enrichment (123% and 68% respectively), and the depletion of other major elements. This change would be expected in an environment of hydrolytic leaching and phyllosilicate production. The strong enrichment of Y in this plot is not explainable and could be a result of analytic error.

Figure Td-3

This diagram shows a near surface section of drill hole

WC-1, and compares barren, moderately altered dacite with a gold-bearing argillized section. The C A sample represents the richest gold horizon encountered on the property.

Because of simple spatial proximity of the two samples 94

(40'), this plot might be more representative of the changes inherent in the processes of progressive argillization and mineralization. The isocon for this plot shows an envelope placed around constant Al with upper and lower limits determined by agreement with Zr-Ba and Ti-Si respectively. The two limits give a mass change from -15% to +2%. No specific gravity is available for these samples, but assuming a maximum density change of 10%, a volume change from -7% to +12% is indicated. This plot is unique in showing a highly argillized progression with strong enrichment of some of the mobile major elements as well as depletion of silica and potassium.

Mg shows a 3X enrichment and Mn shows a 4X enrichment in the highly argillized zone, a trend which runs counter to all other plots. Such enrichment might be effected by Mn-Mg- rich brown calcite veining, though no such veining or calcareous material has been observed in this sample.

Figure Td-4

This plot projects a weakly argillized, barren dacite against a silicified argillized dacite with common pyrite and 0.23 ppm Au. The isocon fit is not tight, and once again a best-fit isocon envelope is drawn around Al, Ti, and

Zr. The median line of this envelope is considered to be a reasonable best-fit. 95

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Figure 8-3 Grant/Gresens Plot Td-3 96

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I I 1 I I I o

Figure 8-4 Grant/Gresens Plot Td-4 97

This figure is typical of most alteration plots, indicating an enrichment of Si0 2 and Kp with progressive alteration/mineralization, and a depletion of most major elements. Ca, Mg, Fe, and Mn are strongly leached, Na is neutral. The pyritization of this sample is not reflected in the FeO content.

Figure Td-5

This plot reflects the change from a relatively fresh dacite to a hematitic weakly argillized dacite with sparse white quartz veins and low gold (0.10 ppm). Once again, these two samples are spatially associated and reliably representative of local mineralizing processes. The isocon fit is good and indicates a slight mass and volume increase of 3% and 4% respectively.

Many of the major elements plot close to the isocon indicating minor component shifts. Si0 2 is enriched by only 8%, while K is enriched by about 20%. Ca and Mg are strongly leached (>50%), while Na, Mn, and Fe are less depleted.

Figure Td-6

This plot displays the transition from a barren argillized dacite to a chloritized, highly argillized Au- bearing dacite. Choice of an isocon was complicated by 98

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Figure 8-5 Grant/Gresens Plot D-5 99

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Figure 8-6 Grant/Gresens Plot Td-6 100 variability of all chemical components. An isocon envelope is based on the commonly immobile elements Al, Ti, and Zr, and the envelope median line is used as a reasonable best- fit. This fit produces a mass gain of 20% with an 18% volume increase. The change in specific gravities of the two samples is less than 2%, supporting the conclusion that mass and volume changes are of nearly similar extent throughout the system.

This plot indicates that the major mobile elements Ca,

Mg, Fe, and Mn are leached, while Silica, Al, and K are slightly enriched. Holding Al constant, as residual Al is taken up in the production of phyllosilicates, indicates an increase in actual silica content. It is reasonable to assume that the Au mineralization in this sample is associated with silica input.

Figure 0v-1 This figure compares a relatively "unaltered" Valmy sample with a hematitic, argillized, quartz-veined, gold- bearing Valmy sample. The uncertainty of the sedimentary analyses is reflected in the wide scatter of data and large standard deviation envelopes. The wide isocon envelope is based on Ti and Zr immobility as (weakly) suggested by element ratios, even though it is realized that detrital Ti and Zr in the sediments add uncertainty to this assumption.

Roughly midline to this envelope is an isocon which besides 101 being the norm of the error range, fits a line reflecting constant Al and constant mass.

No specific gravities are available for WC-7 samples.

However, data from 17 Valmy specific gravity calculations indicates minimal change for variously altered rocks.

Samples range from 2.7 to 2.5, a maximum change of only 8%.

This maximum number is used to calculate possible volume changes based on the limits of the isocon range. In fact, based on the consistency of the specific gravities within the sediments, it is more likely that the density changes are insignificant, and that V A/V c is roughly equal to M A/M c .

Considering the range of the isocon envelope, it is likely that the constant Al median line is a reasonable choice. This indicates a system of little mass or volume change; enrichment of silica and potassium; and depletion of the major elements Ca, Mg, and Na.

Figure 0v-2

The visible change in alteration of these two samples is more subtle than that of Figure 0v-1, being essentially the addition of silica veins and gold. Like 0v-1, this figure reflects the wide scatter of data in the sedimentary samples. The isocon range is wide, and once again, the mid- range line is probably the best-fit based on Al, Zr, and Ti levels and assumed minimal density changes. 102

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Figure 8-7 Grant/Gresens Plot 0v-1 103

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Figure 8-8 Grant/Cresens Plot 0v-2 104

This plot shows an 18% enrichment of silica, and a strong depletion of Ca. The extreme enrichment in K and Rb

(both > 2000%) and strong enrichment of Na (350%) and Ba

(98%) is not easily explained by the addition of quartz veins, except for the general fluid redistribution of mobile elements from the element-rich dacites to the element-poor sediments.

Summary of the Grant/Gresens Plots Any interpretation of the Grant plot is a strict function of the choice of isocon. Actual deviations from the assumed immobility of Ti, Al, or Zr, will result in misinterpretation of the processes involved. Nonetheless, within the error margins carried throughout the plots, certain trends can be identified and, within those limits, can be considered reliable.

Data generated by the Grant/Gresens diagrams is presented in Table 8-1. A distillation of the main points of the diagrams is summarized in Table 8-2 and reviewed below.

Mass and Volume Changes

Actual values range from -6% to +78% mass change and

-2% to +88% volume change. Despite the variability of this data, the overwhelming trend is a moderate increase in mass and volume with progressive alteration. Two plots indicate 105 small mass decreases ( < 5%) while the remaining six plots indicate generally moderate increases in mass and volume. There is no clear correlation between degree or type of alteration or rock type, and the degree of mass and volume change. The small variations in specific gravity of both lithologic units result in changes in volume which are closely coupled to mass changes. Generally, it can be concluded that these metasomatic reactions produce a moderate increase in mass and volume, ranging from about 10% to 30%. This is feasible in the essentially tensional environment of range-front normal faulting.

Major Element Distribution

The dominant shifts of major elements during alteration and mineralization reactions are generally conformable to the basic mobility of those elements. Silica and potassium were generally enriched; Ca, Mg, Fe, Na, and Mn were generally depleted. However, some variations are revealed:

- all elements show departures from the above trends at some point, becoming anomalously enriched or depleted, sometimes to extreme levels. Only Ca never showed enrichment.

- S10 2 wasgenerally far less enriched than anticipated, even when quartz veins were present in the

106

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- common and abundant K enrichment indicates more

potassic alteration and 2") potassic feldspar and/or mica production than was indicated by methods of K-staining, XRD, or thin-section analysis.

- Ca and Sr do not follow each other chemically, in this system at least. In 6 out of 8 plots, these two elements followed opposite trends of enrichment and depletion. An overall review of individual element behavior is presented in Chapter 9. 108

CHAPTER 9 THE TRANSFER OF MAJOR AND TRACE ELEMENTS

At White Canyon there are three primary controlling factors of major element transport: 1) the mobility of elements in dilute low-temperature hydrothermal fluids;

2) the stability of primary and secondary mineral assemblages; and, 3) the disparate levels of major elements in the two contrasting lithologies. The metasomatic character of major and trace elements is summarized individually below.

Major Element Transfer

The unaltered dacite units are rich in rock-forming minerals and major element components. The older sedimentary rocks, conversely, are low in all common major elements except Si. Since the major elements are readily mobile, the net result of fluid circulation is a redistribution and equilibration of these elements on a system-wide basis.

Examination of the data by different methods has produced some conflicting results. To a limited extent, trends indicated by the large array of data points are 109 contradicted by the Grant plots. This is not a problem considering that the plots represent localized individual reactions on a micro scale, while distillation of the entire data field is a more system-wide and empirical analysis.

The discrepancies occur, for the most part, in the

interpretation of the highly variable Valmy section. In this instance, the statistical splits are probably more reliable due to the larger data base and the known error in

the Grant plots. All percentages of major elements reported below are weight percent (wt) as oxides.

Silica

Silicification is one of the dominant alteration

effects of the White Canyon hydrothermal system. Copious

quantities of silica are transported and deposited in

geothermal springs. Even under conditions of advanced

hydrolytic depletion, residual silica levels commonly

increase. Only in the highly siliceous sediments, or in

advanced conditions of abundant clay production are there

indications of Si0 2 depletion.

The Valmy Formation is highly siliceous, reaching 93

wt % Si0 2 and averaging 84%; notably, this is greater than

the two analyzed chalcedony vein samples which contain only

79% and 82% Si0 2 . The fresh dacites contain 64 wt% 5i0 2 and

range from 63% to 88%. Generally, the Grant plots and 110 • o • • • • • •

AO 968.19A e • • • • • o • o o 0 olo .0 0

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1 1 I I 1 1 1 1 I 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 j 1111111)1 o o o 6 (1) Cg 1••• d o MCI CI

Figure 9-1 Au versus SiO, 111

statistical splits indicate an increase in silica ranging

from a few percent to forty or more percent associated with precious metal mineralization and all types and degrees of alteration except clay production. Figure 9-1 plots Au

2 and is keyed to lithology. levels against Si0 , , A clay-rich horizon in drill hole WC-6 displays extreme silica depletion down to a low of 43% SiO r Grant plot D-3 indicates similar depletion in a clay-rich dacite horizon. Considering that phyllosilicates are generally about 45 wt.%

Si0 2 compared to 65% for common feldspars, this is an expected result in an environment of stable clays and acid

leaching of silica.

The correlation between Au precipitation and Si0 2 accumulation is not strong, as is shown in Figure 9-1. The

dacite samples show a very weak positive correlation between

added silica and Au content; but the Valmy sedimentary samples display a weak negative trend, indicating minor depletion of silica with alteration.

Aluminum Aluminum is ubiquitous in most silicates, but reaches

its highest levels in hydrothermal alteration minerals.

Kaolinite and muscovite average 40 and 38 wt.% Al 20 3

respectively versus about 20 to 25 wt.% Al 20 3 for feldspars

and plagioclase. Residual aluminum levels are thus I12 stoichiometrically maintained (no depletion or enrichment) during propylitic and potassic types of alteration of common rock-forming minerals and are increased during sericitic and argillic alteration. From the Grant plots, the Al content of the dacite is shown to be roughly consistent, with increases in silica offsetting the progressive enrichment of residual Al.

Conversely, the Al-poor sedimentary units are enriched nearly two-fold during alteration, reflecting the production of phyllosilicate minerals as well as the general redistribution of major elements.

Potassium

Potassium is a common component of both primary and secondary feldspars and mica minerals. Erratic K trends in both the sediments and the dacite may represent initial potassic alteration which is ultimately destroyed by superimposed argillic alteration and the depletion of K.

All data show K 20 enrichment in both rock types with increasing alteration and mineralization. Potassium staining demonstrates that adularia is not significant within altered rocks, and thus K enrichment is probably associated with sericite and/or illite formation. Rubidium mimics K trends throughout. No correlation exist between K levels and gold. 113

Calcium Calcium, measured as CaO, is a major component of pyroxenes (approximately 18 wt%) and plagioclase (about 8 wt). It is essentially absent from secondary

phyllosilicates with the exception of some illites which can

contain about 1 wt % CaO. Most Ca released from rock-forming

minerals produces calcite or gangue or is flushed

from the system. Pervasive weak calcareous alteration is one indication of propylitic alteration. At White Canyon, calcite is notably rare, and gypsum is

absent. Few of the drill samples were calcareous, and this

is reflected in the very low CaO levels throughout the

system. This is probably an indication of the low pH

conditions associated with acid vapor leaching. Within the dacite, the Grant plots show the depletion

of CaO in every instance of alteration and mineralization.

For this discussion, Ca, Mg, and Na could be combined, since they follow nearly identical trends of depletion with

progressive alteration. Disparate levels of these three

elements tend to equilibrate within the two rock types, decreasing radically in the volcanic rocks while increasing

slightly within the sedimentary unit. The Ca-poor Valmy

Formation averages 0.25 wt% CaO, but increase to levels

similar to the volcanics with alteration. There is no

correlation between Ca levels and precious metal content.

The relationship between Ca, Sr, and Ba, is examined below. 114

Magnesium

Magnesium is a major component of chlorite, and thus is

enriched during propylitic alteration. Within the White

Canyon system, MgO follows the trends of CaO, and is rapidly

depleted in the dacite while being progressively enriched 2

to 3 fold in the siltstones. Taken in context of the

similarity with Ca, this possibly represents a lack of

propylitic alteration in the dacite and weak propylitic

alteration in distal portions of the Valmy Formation.

Sodium

The only common host for Na is feldspar minerals, thus

the dacite samples show severe depletion of this highly

mobile element with the deterioration of plagioclase. Na

follows the trends of Ca and Mg and is enriched four fold in

altered sedimentary rocks, perhaps as an adsorbed ion in

phyllosilicates.

Iron

Iron levels of the fresh dacite are roughly 6 times the

iron levels of the Valmy Formation, 8.2 wt% Fe 20 3 versus 1.3

wt % respectively. Fe is easily mobilized and equilibrates

to near-equal levels in the two rock-types during

alteration. The Grant plots show consistent depletion of Fe

in the range of 25 to 50 % of orininal Fep3with 115 progressive alteration. Secondary iron oxides are common in both rock types, primarily as hematite with less common magnetite, limonite, and ilmenite. Highlighting the overall low pyrite content of the system, sulfide bearing splits show no overall Fe increase over other groups. Despite the clear correlation of Au mineralization with bright red-orange hematite/limonite/goethite mineralization

(i.e. "good colors"), there is no overall significant Fe enrichment associated with gold.

Trace Element Transfer

Rubidium - Strontium The intermediate mobility of Rb and Sr produces erratic values and poorly-defined trends. Overall, Rb values are 2 to 4 times higher in the dacite than the siltstones. Both Rb and Sr show the tendency to increase in the sedimentary rocks and decrease in value in the dacites with increasing alteration. This probably reflects the adsorption of these two elements into clay minerals. In the Grant plots, Rb clearly follows the trends of K; while Sr reacts generally in opposition to the trends of Ca. Ratios of Sr, Rb, and Ca do not reveal consistent geochemical coupling between any of these pairs. 116

Chrome Cr levels are very low in all cases, and essentially nil in the dacite. Where lithology was obscured by alteration, the higher levels of sedimentary Cr proved useful as an immobile indicator of rock type.

Barium

Barium deposits are indigenous to the Paleozoic sediments of Nevada; a large bedded barite deposit lies within 2 km of the study area. Conversely, the Ba level of most average intermediate igneous rocks is relatively low, roughly 300 ppm (Rose et al., 1979). At White Canyon, Ba averages 1640 ppm in unaltered dacite and 810 ppm in the sediments, a reversal of what would be expected. The anomalously high igneous barium probably resides in the K- feldspar lattice and reflects magmatic contamination from underlying Paleozoic sediments.

All Grant plots show Ba to be nearly immobile or enriched in alteration reactions. Ba levels remain high in all analytical dacite splits, and increase slightly in altered Valmy splits. Gold-bearing Valmy samples show a two-fold increase in Ba over barren samples while gold- bearing dacite samples have slightly lower Ba than barren samples. 117

The source or nature of the persistently high Ba is not known. Ba and Sr follow similar trends (neither follows Ca) as reflected by consistency of ratios and the Grant plots; this perhaps reflects the tendency of Sr to substitute into barite, although barite was not observed visually or in

X-ray analyses.

Yttrium - Zirconium - Niobium

This suite of "immobile" elements provides little useful information. Y and Nb data suffer from being close to detection levels and are essentially unusable. Zr ratios with Ti and Al indicate relative immobility and are used as such in the Grant Plots.

Overall, values of all three elements are higher in the volcanics, but attempts to utilize Nb/Y ratios to define obscure lithologies were not successful. Zr in combination with Ti, Al, Nb, and Cr proved to be useful in defining the

Ov/Td boundary. A plot of log Zr/Ti versus drill hole depth clearly delineates the lithologic boundary in drill holes

WC-2 and WC-3 (Figure 9-2). 0

0

0 0 0 o o

0 o OSE, o 00E Le) o OSZ o OSL C.) SOL MC OS St

SEE SLE S8t D ost o atZ nicri c) OLL I OLL OOL gic if St St

OPE 00e SOZ SSE F., " OK I Oa C.) 09L OLL OL St SL r 0 09 0 S LE 0 09E N OZZ -.1 C.) 1 0 591 I OK C..) SOL MC 0 02 09 o OS o St 0 SC o 09Z o o OCZ 00Z 091 SC t 1:j11:3 OIL o 06 OS D SZ rP 0 1 C•1 v.• a> EPt Li) IN o LC) (1i CJ

lç --T eoe=e 119

Summary

The following trends are indicated:

- abundant silica enrichment, SiO,, depleted only in clay horizons;

- weak Au/Silica correlation, trend is weak positive in dacite, weak negative in Valmy Formation;

- Al depleted in altered dacite, enriched in altered

Valmy Formation;

- secondary K enrichment common, most likely in sericite/illite;

- CaO strongly depleted with no gangue production, indicating low pH conditions;

- MgO and Na 20 strongly depleted in dacite, weakly enriched in sedimentary rocks;

- Fe moderately depleted in all progressive alteration;

- no analytical correlation between Fep 3 and visible pyrite or iron oxides;

- pervasive Fe oxides indicate overall oxidizing conditions;

- Rb, Sr depleted in dacite, enriched in Valmy Formation;

- Sr (uncharacteristically) does not follow Ca;

- Rb (characteristically) does follow K;

- Ba is anomalously high in dacite, anomalously low in Valmy Formation, and anomalously stable during alteration; 120

- Sr follows the trends of Ba;

Overall alteration effects of the system are four-fold: 1) pervasive silicification, deposition of result of the hydrothermally transported SiO,, as a cooling of silica saturated fluids;

2) accumulation of residual Si and Al in secondary hydrated aluminum silicates;

3) redistribution of major elements toward a homogeneous system-wide norm;

4) introduction of trace amounts of base and precious

metals, and certain trace elements. 121

CHAPTER 10 EXPLORATION CRITERIA

Effects of the alteration processes of White Canyon were characterized in the previous Chapter. To conclude this study, The White Canyon hydrothermal system is assessed from the standpoint of its significance as an exploration target. Those features which indicate mineralization as well as those which might indicate lack of mineralization are discussed below, and exploration recommendations are presented.

Exploration Criteria

Indications of mineralization Unfortunately, the list of positive indications of mineralization is much shorter than the list of contraindications presented below. Positive indications of mineralization potential at White Canyon include:

- a regional geological environment conducive to economic mineralization. The known affinity of ore systems for Tertiary volcanic rocks, plus the proximity of Carlin- type systems support White Canyon as an area of high mineral 122 potential. - consistent detectable precious metals. The high

incidence of precious metals from White Canyon surface samples clearly justified continuing exploration efforts.

- well developed chalcedony vein set. The size and extent of the vein set plus rare breccias and pyrite indicate potentially significant mineralization.

- obvious structural control. Structure is an absolute

criterion for mineralizing systems, but its presence can be masked. At White Canyon, structural control is obvious, and was one of the initial indicators of potential mineralization. From the above list, the incidence of detectable precious metal mineralization is in itself enough to justify

further exploration. However, the negative indications listed below could be significant in developing criteria which help identify those deposits which possess economic

potential from those which do not.

Contraindications

The 1984 drilling program revealed that subsurface

mineralization is of no greater extent than surface

mineralization. Possible indicators of this lack of deep

mineralization include:

- lack of dynamic brecciation. The most critical

exploration criterion for this type of deposit is widespread 123 and well developed hydro-dynamic brecciation. The lack of explosive or hydrofracted breccias, and the rarity of multiple-generation breccias suggest an absence of continuing episodic explosive activity which is critical in creating physicochemical fluctuations which localize precious metal deposition;

- consistently low precious metal values. Just one or two isolated ore-grade (or higher) precious metal values either in wall rock, or more importantly, in veins, might indicate significant mineralization within the system. The complete absence of high Au or Ag values from the 255 surface samples is a negative indication;

- lack of significant pathfinder elements beyond the margins of mineralization. Elevated values of As, Sb, or Tl possibly would indicate a more heavily mineralized system;

- lack of sulfide minerals. Although base-metal sulfides and pyrite are commonly not abundant in most hot spring ore systems, the sparse pyrite and the complete absence of chalcopyrite, arsenopyrite, stibnite, and other trace sulfides could be a negative indicator in this deposit;

- limited silicification/alteration margins on silica veins. Although statistics presented earlier indicate significant mineralization in dacite wallrock, the common sharp vein margins and very limited (or absent) alteration envelopes of most veins is probably a more significant 124 characteristic of this barren system;

- lack of extensive surface alteration or alteration zoning. Phyllic alteration, opalized caps, or wide-spread argillic alteration are considered classic surface indicators of hot spring activity. These characteristics are absent at White Canyon, and it could be assumed that this is an important indication of the lack of significant mineralization. However, on the other hand, subsurface information indicates extensive argillic and advanced argillic alteration at depth, suggesting that such surface indicators should not be considered absolute.

Exploration Conclusions and Recommendations

1983 Exploration Program In retrospect, it is easy to suggest changes in the Chevron exploration program. Initial reconnaissance and surface sampling were well performed and provided a good data base on which to evaluate the early potential of the property. Although precious metal values were low, the consistency of detectable gold and silver clearly justified continuing the program. The initial drilling program expanded the information base, but did not go far enough to answer the exploration questions at White Canyon. Specifically, the wide spacing 125 of the drill holes provide no profile of continuity, and more importantly, vertical drill holes are a poor method to test near-vertical structures. Although important information was generated by the drilling program, the ground was not adequately tested to justify abandoning the large dollar investment by Chevron.

Despite the very low grade mineralization encountered in the first round of drilling, a second drilling program of two to three holes would have completed the testing of the property and allowed a decision of abandonment with a high degree of confidence. The purpose of an exploration program is to test the mineralization potential of a property. It is imperative that every drill hole have a well defined target, and that completion of that hole answers the questions posed by the indications of mineralization. Significant questions still exist at White Canyon, specifically:

- the massive chalcedony veins of White Canyon proper were not encountered in the drill holes. Do these primary targets exist at depth?

- very consistent mineralization was encountered in two drill holes. What is the trend and extent of such mineralization?

- Considerable advanced argillic alteration indicates extensive subsurface hydrothermal activity not indicated on the surface. What is the nature and extent of this 126 mineralization? - what is the three dimensional nature of the system?

A limited amount of followup drilling could answer these questions. Specifically, the program should:

- incorporate angle drill holes to assure either interception of the primary targets or confirm that they do not exist at depth;

- incorporate angle drilling to provide more reliable interval thickness of the near-vertical mineralized structures;

- incorporate angle drilling to generate three dimensional data for spatial interpretation of the system;

- develop directional vectors and step-out drill the two highest grade intercepts of WC-1 and WC-7. Such holes would: (1) be a last effort to intercept high grade values;

(2) test the extent of known mineralization; (3) provide some two dimensional spatial information.

Such a program would require no more than three reverse circulation drill holes of 200 to 500 foot depth. It would provide confidence on the limitations and extent of precious metal mineralization. If no significant increase in mineralization were encountered, the property should be dropped, and it then could be dropped with a high degree of confidence that the economic potential of the system has been tested. 127

Exploration Criteria Future exploration for such deposits should consider the following: - dynamic breccia textures are essential, especially multiple generation breccias;

- argillic alteration and acid leaching are essential, but these effects can be masked;

- although As, Sb, and Tl are questionable as pathfinders, their clear association with precious metal mineralization easily justifies their utilization in the search for epithermal mineralization.

- structural conduits are essential; size of the structure is not critical. In brittle terrains structure will provide fluid conduits; in less brittle environments, structure can provide ground preparation. - frequency of detection of gold in the country rock is as important as elevated values, but the absence of either could be a negative indication;

- Au and Ag are the best pathfinders, precious metal mineralization leads should be examined in detail and followed to exhaustion.

128

APPENDIX I

SURFACE SAMPLE ANALYSES

n, m., a4iple Au* Ag* As* Sb* 'J.). Zn 71 c rib W 82001 0.06 1.4 10;, 0 6 ¼)8n 5 4..0 1 0 c 82002 0.14 ,..., 70 , 82003 0.13 1.7 34 11 In 0 82004 ,(I 1.7 14- J n ol n 82005 j)..,), 4. 89 8 0 AO 82006 0 .15 1'J. , .r..) 5 n c loc. 82007 0.17 4.,,, iJJ s 82008 0.07 4 OC 6 82009 0.04 0.9 ,,oc c, n o cc 82010 0 .08 ,..,.w ,, 2 1 0 lc 1 82011 0.13 I...) lw 01 0 82012 0.44 4.1 ..., n 4... 82013 0 .3 40 1 64 5 4.,82014 C.1 n 0 56 6 n 1 o n ,1 82015 ,.,. , .,.4. 11 . 82015 0.04 1.4 170 4 4 10It 4,nn 8 6 1 '7f100 e) 0 .1' 82017 0.05 n . iW..1 C. V 9 ,, 9 4 n nu 1 .-xl c 0c n Cr 82018 1.?. . , 4. ,'J,) 6 , 4 4-, C. n 0 L)82019 1 .1 1 07 , 82020 0.15 0.7 147 3 82021 0.11 S 36 3 00000 n in 01 ,4„4.4 ,.,4 5 J1 4 AO 84,4, 0.09 ,, 7 .,82024 ¼).¼).Jn n 1 .5 170 5 n n o lc L/82025 .¼).I,) , ,, S 82026 0 1.4 60 5 n no n 1 0 1 82027 4 , , n 1 n ..7 nol 0 nn 82024.8 ,.,, 4, , 4 7 .., 14 9 82029 0.09 0.7 52 3 0 -7 00 a G.I82030 0 .11 217 4 6 4 44 ,., 11 •M 4.482020 0.17 n n 217 c¼).., c inII,) 17 4 1,, 820 31 ¼).Ini ,.l., 1 0 180 11 0 0 in c 10 4..W82032 0 .24 324 ,, 4 7 21 ¼) IJ 82033 0.17 2.4 55 40 1 ino 82034 0 ,4... 9 1 n 00 IG82035 005. . W, 4 62036 0.11 2 15 4 82037 0 .12 4.4nn 74 11 ,82038 0.13 1 9 ...,n 0 0 -7 W.I82030 n4. 2 82040 0.06 1.7 4 3 0 82041 0 0.9 161 5 4 0 4,00 3 , n c oo 82042 0 ,.,,). ../., 4 n 82043 0.25 3.4 85 4 c, 0 11 4 4 O."82044 1.4 4,0= 0

129

APPENDIX I (con' t)

et-. W j ASSolyjle AU Ag .....4,._ o rb Zn Ti F Mb 82045 vn 1 6 Q%, A'"82046 0.08 12.2 ..., 4 n 82047 vn 0.3 6 ,_ ,,_ 1n82048 nv v.,n o ,n 82049 0 0.2 ,c 4 n n 82050 0.16 4.4. 484 5 82051 0 0.6 15 3 82052 0 0.4 5 2 n I'l C 82053 Li L).¼) 17C g o 1 82054 0 0.9 L) , 82055 0.05 ,.vn o 10 2 82056 v.vvn no 1,..,» ') 48 3 a oc 82057 0 0.9 lno,,..,.., 6 w <,.) vv 12 -7,1 82058 0.17 2.1 It 4 n 1 '70 82050 W . I 6. 7 (Li 15 1 c 10 1 82060 0.06 I.W ILL i 7782061 0.56 4.8 14 70 82062 0.04 1.6 FW g n 82063 C v.,n c 1 6 C. 1 c 1182064 0 , ,.) n no 1 C 3 782065 v.vv i . n.) s.)

482066 0 1.5. ..., 1 582067 0 1.6 1 , o 8206vo 0.06 nv.v o nv 820E9 nÇ) 1.3 10 1 n n a lo IL)82070 v v. W 2 000'71 n We-Wf i 0 0.5 v 4 (1 n a 82072 Li y.y 3 4 -IO 82073 0.06 0.5 t n, \., cc 82074 v,..,n . -,(1 3.6 ov 7 vv I) 92075 nv 0.5 n 1 .882076 J 0 4 82077 nv 0.5 10 ,..n n c v,82078 0.03 . 4 0 ,,v82079 vn nv., c on 4 n 82080 0.06 5.6 5 v 1 c V00 82080 0.09 I.W U 8 oo 82081 0.06 1.1 Li 0 vv 4 82082 0.19 2.0 9 16 11 i o I A 82083 0 1.* 14 92 6 82084 vn 0.7 19 Li 14 47 4 82085 0 1 n n o 82086 V V.W 9 1 3 11 73 5 n '7 1 n o 82087 0 W.f 17 C. v60 4 l o n emee 0.04 0 .5 Iv C. n 1 1 82089 ¼) 1.. 10 C. 82090 0 1.4 82091 0 0.7 6 vn

130

APPENDIX I (can't)

A. ck Samole Ag As Cu Pb Z Ti F Ni W 82092 0 0.8 12 0 82093 0 0.9 5 0 n n 8209410 , , 82095 0 0.9 -in.... 1 n 7 in V.820960 f IV V 82097 0 1 ..0o 34 8 82098 0.4 0.8 11 1, on n 82099 nu. u. nu . oQ 10 . 0.14 82100 0 1 ..0o uc 0 n on 1 US82101 V.4 9 n n n w 82102 u., 12 6 82103 0.38 43.2 27 .n 0 Q 82104 0 1..0 o 0 no U. 82105L) 0 35 20 1 c no 82106 0.04 I.V 4W 3 n n n w V.482107 4 0 o 82108 0.12 1.1 34 Q 82109 0.03 1.6 51 .n u.82110 0.04 0.6 on 1, n no L.,82111 u.0 3 °P112 0.03 1.7 264 5 82113 0.05 2.6 24 4 no nm 1 82114 0 v.,.., ..I,J . fl 0 '7 V.V82115 0 f 1 ft 'D n ..,82116 0 u. 5 US 82117 0 1., o 76 6 82118 0.06 1.6 49 4 82119 0.03 1.7 40 4 82120 0.03 1.4 40 .n 82121 0.07 14 .8 ..nn 1. 1 n 82122 C 1 . 4 1 6 0 onino n no n n W.VV V.4 4 0US 1182124 C 0.5 2 ononino 1 o c V4V4I4V 0.08 I .I.) V 782126 0.06 0.3 0 co82127 0.07 1 .9 uu 6 82128 0.04 0.6 3 Qo 82129 (1 in 0.7 9 2 82130 0 0.8 197 17 82131 0.03 1. 85 20 n 82132 0.04 1..0 o C. 0 no -n 82133 0 v.,.. Q 0 n 1 .1.1 82134 C ,...., 44 V n 1n 982135 u ..4 1

82136 005. 13. 4 US '31 82137 0 1.4 I

82138 0 1.4 4 o •

131

APPENDIX I (can't)

r..), Sarple ...... 4 Au Ag As Sb rb Zn Ti F MD 4 C n 82139 0 1.5 V L, 82140 ,„,.., 0.13 0.7 on o, CO 0 82141 0.23 0.6 L.C.) Q 32142 0.04 0.4 84 4 n 1 0 '>0 82143 I .Q VV 4C. 92144 0.14 0.2 C.0 0 0 ,_4_82145 0.07 1.5 on 1 82146i0 ,•,A 29 1 1 0 G 82147 0 I.k., Q 0 82146 0 1.7 8 n, 1 G 7 n 82143 0 I . , 4 n n 82150 L) 1.4 2 , ,82151 n 1.4 1 6 ,n oniro 1 0 10 1 V 1,4 0.13 I .4 14 I 04 82153 0.2 4.5 16 i 0.03 1 0 c n ,.., I . 4,82154 0 .28 9 L., n 0 10 n .12 ,.,82155 0 30 IV , n n -1 1G Q.( Iv82155 n., 7 0.07 onic-o V41,1 C 0.6 4 1 0.06 001 00 n 7 n no V4IVV 0 V., 9 1 V.VW n ”1 n n ,82159 1.4 , , , n lo n n L)82160 1.1 IL., L, k.1 10 1 n 82161 0.12 1 I(...n L, .3 L) ,,821 52 n 6 1 80 on 8 18 118 1 .70.07 001c0 n 00 0 1 VGIQV V.V4 O.V° 100 17 7 14 74 0.7 0.04 c 10 n o 82164 0.14 4.2 74 , 4 0.9 IL, V.V 0.,, 82165 0.13 2.7 ,,00 10 4 ,c 48 2.6 0.03 nn A • v..s_ -,-82166 3 .6 15 L) 0 9 29 0.7 0.03 , 82167 0.48 3.6 57 11 5 0 43 0.8 v.05n

) n cm L). 32168IC' 3.9 42 6 4 3 16 0.5 vL.,.,, n 0 n n n o n (10 , ,.,.::, 821690 .8 , 1 3 11 Q.4.- v.(..(Q 13 0G 0 , Q.,22170 0.17 s.Q 4 0.9 10 0.4 0.02 82171 0.09 1.4 01 0u 6 ,c 9 0.4 0.02 c ,°'172LIC 0 1 98 5 16 54 0.6 0.03 n o no 1 c L) C., 82173 1I. .., 1 7 660I., 0.05 n 1 0 10 GO G in no IL'82174 I.0 Qk.) Q 8 L) 0.5 n,.w.., oc o ,82175 0 1.1 ,, 70 17 0.5 0.02 1 on 82176 u , .4 40 7 7 14 31 nt....W o 0.04 IC82177 0 .08 1, .,c 180 10 4 13 43 0.6 0.06 00 0 o n 82178 0.06 1 (.t.0, Jf L) 4 10 v L) 0.06 ann o o L)82179 0 n.,.,n ...... , , 15 56 0.9 0.04 A o n') 32 ..r180 0.08 0.9029 4 0 .0 w ,.4 0 .02 1 h ; 4 82181 0.05 . 7; g 3 0.9 10 0.4 0.02 82182 0.04 0.6 9 40 ,0 0.9 10 0.3 0.V4 0 C V 82188 0 0.8 10 V 18 92 0.7 0.02 82184 0.04 1 30 0, ,0 0.916 ,..c.n n nu.u, no n n 0 M. o a n 0 tJ . 82185,.., , J C. L, 0.9 12 u., 0.03 n on 0 10 00 no 82186 , L). I L) le... Q 0 ,, u., 0.08

132

APPENDIX I (can't)

n Sample ...4.1 Au Ag As Sb Pb Zn Ti F fvb W n o n 82718 0 Q. C. 3 5 17 148 0.5 C. 07 1 1 c n 0 841 98 0 1./ Y 10 9 17206 1.1.1.) 0.07 n I Q 82199 , 75 9 12 14 112 0.4 0 .28 82190 0.05 4.,ni 49 4 8 8 30 C .4 nn 0h101 h 1 7 no 0 4.ue..1.::), 4., 160 6 I 15 1 0.03 onion n 1 2 ¼) n .,, 170 4 4 11 9 1 0.03 82193 0 0.6 10 4 55)m 13 411 ...h 02. 1 a c c0 A 1n n na 82194 0 .04 ..,..., .-,..) -r ,./ Q 29 it I 0 A n a. 17082195 0 ,., V ,i- 19 14 ... 0.04 0 C hl Ch n na 82196 0 0.0 41 Y Y GI Y4 1.9 Y.YY 82197 0 0.9 170 5 5 19 12 0.4 0.21 n 0 0 1C n o . 0.682198 240 L. ,./ . .-+ 9 ... 0. 19 .e.82199 0.04 0 .5 on 9 C.a 18 le 0.4 0.14 1h Y.I82200 n 1 1 i.,4 230 19 2 .4 13 0.030.8 a 4 8220 1 0.08 300 11 4 13 50 0.8 0.03 a a 82202 0.08 44. 17 4 4 0.9 135 5.4 0.02 a 10 0a A n n no , 82203 C 150 6 . ,. Y4 1.4 Y.YY h0 nn n n no 4.84404 0.06 0.9 4 4.,.., 4 1 8 0 . 6 82205 0.03 0.4 5 1 8 49 0 0.03 OR no no C C YY82206 0.05 4.8 4W 4Y Y W1.9 0.04 OR n i 1 'D SI82207 S) W.f Y 1 1 3 L),) 0.1 0.06 onnno A n 10 o n n w44...... , 0 1.1 -+ ,.., n SI l.1 101 V.4 0.1 n A ("209 1.0 2 4 v , 0.9 400 0 0.04 82210 0.05 11 3 0.9 11 0.2 n,..,..,,) no onnii , 1 0 n 1 0.03W4411 0.4 , . 0.9 0 .., 0.03 onnin 0 0 00 h C Ar n n n nn w4.4.,4 0.06 ..).,) ,,J C. Q 0.9 -t..) 5/.4 ,.., .,.,4_ onn i 2 no n n W44IY 0.04 1.0 GY 4 C. 1 12 0.4 0.02 onnim n n-7 1 ac n 1 n nn Q. CA),,,,,... ,r-+ t., .s., r 1 .7 6 , 5 0.9 n ,,..,..e_ I .44onnic ,. 0.1 2.6 .c 3 0.9 31 0.3 0.04 onnnn no c al n no .444. 1./.03 0.7 4Y Y 4 GI 0TY ' 1.1 5./.5/SI onnni n 2 W4441 0Q. Li. SI 27 .' .o 0 . 9 9 1 0.02 onnnn 2 n 12 2 c 1 n nn W4444 0.00 ...,.4. 1Y Y Y 1 10 0.1 51.5./C onnn2 V4 Y 0.04 12. 8 0.92 4 41 0.1 0.0244 A (-1 .2P 1 0 T 8222 w Ww 1.0 14 e 4 9 35 1.6 0.03 onnncn 11 c ni .444. V.II 1 .3 16 . 4 I 4 I 0.1 0.02 „),V-YD.= _,,,, 1 no n 0.04 , 4W G CYTD'DC U4Y YV 0.12 1.4 114 6 on22,-.7 nn oc 2 W4YYf 0 4.4 YY Y 0.1'D'D° an 1 V4YYQ 0.03 1.1 GY 1 n 2 n 82339 0 .04 ... 2. 6 Q n A ,) 82370 0 v., 74 , 82371 0 0.6 107 2 82372 0 1. 132 4 8073 n 1.1,., 257 7 1 ... 82374 0 I.Y 60 1 1 in n IC.82375 0 4

W4276 0 1.3 17 1 82377 0.13 1.4 114 2

133

APPENDIX I (con' t)

Ed-rpole Au Ag As Sb Cu Pb Zn Ti F MD W 10 0 82600 0.04 0 .8 I, J n 00 ,82601 1.7 4, 7 n n a o y L)82602 y.y 1 n n a c L)82603 y.y , 4 h c 0 82604 w 0. 3 , C n nn 0 ') 82605 V V.4 V 4 A h 82606 .-r 0.04 0.5 c- n a n ,_82607 0 y.y 2 0 82608 C 0 .2 0L) ,_ i 82609 y0 no aI-:) 4. n h A c 82610 u e...., 60 , 0 82611 0.1 ,. . 1I 4 82612 0 .28 ,.,n a 183 4 82613 0 .05 1,., 0 15 82614 0.04 4.3 16 c, 82615 0 3.4 ,0 0 82616 0.04 1.7 26 ,0 A ') C' 1 82617 0 ,.0 u 82 618 n, 1 .6 ,.0 ,c c 1 82619 0 0.4 , I n nc c 82620 y y.y U 0 ,,,,,,nan1n , 0.7 16 4 n A ,82622 0 .8 6 w n nn C' 1 V 82622 V.4 , 0°)P1/1 0 0 W4w4f, W 0.7 V 4 oacnc n n n us.y4vy y y.y 10 4 n 82626 , 0.4 10 1, n n 0 ,,82627 0.03 9 4 n 0 10 A 62882 0 V., 1 ld 4' 82629 0 1.6 lc , 82630 ,n 1.5 ,c 17 n c 7 , y 82.631 2 7 n a ,...,82632 0.03 . 18 11 ,82633 n 0.7 11 ,c,0 56 ni82634 , • , ....,..nn 7 n no 1 o co ,, y.yy Li8 2635 1. 7 0 i 82636 0.09 0 ,,. 63 0 nn Li82637 0.03 44 , 82638 0 0,., 0 0, ,0 n c 0 82639 0.06 e...y 5 , hh CC82640 0.05 1 '-t "3 n ..).y ,, 82641 0.06 . ° y ,..,82642 0.03 n . c 12 i, ', D 00 82643 0.04 ,.,, c,c, ,.., 0 00 ,J, Ic82644 0 1 . 4 82645 0 1 29 4

n ,) ,1 lo ,> ,.,82646 4..4, 1,,, C n c 1 82E47 y 0.8 y 1

134

APPENDIX I (con' t)

. pb 7,, S37619 A..I Ag AS ao O., 4,11 Nt 1 82648 0 n,...., o 5 , no n n ,,°"?.649 0 ,., C. , 82650 0 4.1 ,o i, ...... ,,onc.ci , L.,n 4 .9 ,,oc 7 82652 0 0.8 ,c n n ac 82653 , 4 ,."..1 o 1 n n I.,82654 .., ..,'D onpa: 1 o l.N...,..,,,./ 0.04 , ..., 1¼) 82656 0.03 s n 82657 0.05 4 ,c 82658 0.02 4.6 ,A 82659 0 o,., c 6 82660 0.03 6 3 ,.,n 4.82661 n,.., n 0 .9 ,n 0n i G. 82662 . I 1 0 82663 0 n 1 0 82564 0 1 • 7 ,..,...,h n 0 n 1 o n 82665 51 , . , 0 .9 , 1 n 82666 1.1n ,.,n n ,.., 82667 0 ni, . 1 1 ,n Cn n n 82668 ,.,... 1 V 82669 0 2.1 1 0 82670 0.09 ,o 14 4.n n n82671 sI.) ,., 20 1, 82672 0 1 4 i 82673 I.)n 1.6 1 82674 0 1, . ,i 0.0 n n n , 82675 I_1 ,., 1 n, n n L.482676 0.9 n '1 4 82677 I., 1 n n o n 82678 1.1 C-+51. C- n 1 0 I.) 82679 1. kJ 1 82680 0 1.7 0.9 n n 82681 ¼) C. 1 ni 4. 82682. C I 1 ono- 1 514.1.1W1J 0 1. 410 0.9 n 1 o 82684 ¼) I. '.) 1 10 82685 0 n .1. 1 n 'D 82686 0 4.,/ 1 82687 0 1.9 1 82688 ,n 1.6 7 n n o 82689 1.I ,., 0.9 ni G. +582690 0 1 n n c-82691 , 1 82692 0 1.8 0.9 82693 0 1 ,.,c 1 82694 0 1.5 0.9 82695 0 1.9 1 APPENDIX I (con't)

A,,, ct-, n, Sarple Au ,-,,j AS ,../..4 82696 C 1.6 0.9 82697 0 2 1 82698 0 1.7 1 82699 n, 1.9 2 82700 s.'n 1.4 1 82701 0 1.3 nnv..; 1 0 82702 0 i..., 1 82900 s.)n w.4.n n 50 0.41 82901 0 0.19 99 1.11 82902 0 0.2 104 0.43 82903 0 0.2 60 0.25 n n.) n n 7n 82904 W.,, ,, ¼i.. 14 0.44 max 0.56 43.2 484 20 ,.,no 25 660 5.4 0.28 14 15 n n n n n n man 0 0.19 0.9 ,., 4. ¼) 6 w 0 C. C. swg 0.05 1,81",, 3.7 ,., 8.9 51 0.7 0.05 ,c ,0 0 0 n 0 n nr n o s.d. 0.08 2.70 SO 3.9 ,., 6 .6 89 V.W V.,....1 4.. L., 4.1 000 70 10 n = 344 344 ,,, 309 78 rt.) 78 65 72 11

* for Au, 0 = <0.02 ppm * for As, 0.9 = below detection * for Sb, 0 = <1.0 ppm 136

APPENDIX II

WC DRILL-HOLE ANALYSES

Assays for White Canyon Drill Holes WC-1 through WC-7

Au less than 0.02 ppm = 0 Ag less than 0.1 ppm = 0

DRILLHOLE WC-1

Sample Au Ag Sample Au Ag

wcl 5 0 0.6 wc1 165 0 0.3 wcl 10 0 0.8 wcl 175 0 0.4 wcl 15 0 0.5 wcl 180 0 0.4 wcl 20 0 0.6 %Tel 185 0 0.2 wc1 25 0 0.4 wcl 190 0 0.2 wcl 30 0.07 0.6 wcl 195 0 0.3 wcl 35 0.08 1 wcl 200 0 0.3 wcl 40 0.23 2.3.._, wcl 205 0 0.9 wcl 45 0.58 3.5 wc1 210 0.08 1.9 wel 50 0.45 3.5 wcl 215 0.21 2.4 0 1 wc1 55 0.42 ,,. wcl 220 0.22 3.1 wcl 60 0.35 2.1 wel 225 0.31 2.4 wcl 65 0.3 1.7 wcl 230 0.21 2.5 wel 70 0.35 2.5 wcl 235 0.22 2.4 wcl 75 0.27 1.9 wc1 240 0.23 3.1 n wcl 80 0.2 c. wcl 245 0.07 1.3 n n wcl 85 0.14 c.c.. wcl 250 0 0.5 wcl 90 0.16 2.4 wcl 255 0.19 1.3 wc1 95 0 1.6 wc1 260 0.27 2.4 wel 100 0.21 1.8 wel 265 0.24 2.4 0 0 0 0 wc1 105 0.21 ,..,. wc1 270 0.25 ..,,,. 0 0 0 0 wc1 110 0.13 ,...,. wc1 275 0.22 ..,..,. wcl 115 0 0.7 wcl 280 0.23 2.5 wcl 120 0 0.2 wel 285 0.15 2.4 wc1 125 0 0.2 wc1 290 0.16 2.5 %gel 130 0 0.4 wc1 295 0.14 2.2 wcl 135 0 0.3 wc1 300 0.14 1.9 wcl 140 0 0.2 wel 305 0.11 2.4 wc1 145 0 0.3 wel 310 0 0.4 wc1 150 0.03 0.8 wcl 315 0.1 2 wc1 155 no sample wel 320 0.14 2.2 wel 160 0.03 0.6 wcl 325 0.14 2.2 137

APPENDIX II (con't)

DRILLHOLE WC-2

Sample Au Ag Sample Au Ag wc2 5 0 0.2 wc2 180 0 1.4 wc2 10 0 0.3 wc2 185 0 1.4 wc2 15 0 0.4 wc2 190 0 1.2 wc2 20 0.03 0.8 wc2 195 0 ,,, wc2 25 0 0.9 wc2 200 0 1.4 wc2 30 0 0.3 wc2 205 0 1.4 wc2 35 0 0.4 wc2 210 0 0.8 wc2 40 0.03 0.3 wc2 215 0 1 wc2 45 0.03 0.9 wc2 220 0 0.8 wc2 50 0.08 0.7 wc2 225 0 1.3 0 A wc2 55 0 0.5 wc2 230 0 0,. wc2 60 0 0.5 wc2 235 0 1.2 wc2 65 0 0.4 wc2 240 0 1.4 wc2 70 0 0.7 wc2 245 0 1.3 wc2 75 0.04 0.6 wc2 250 0 2.3 wc2 80 0.05 0.5 wc2 255 0 1.7 n n wc2 85 0.04 0.5 wc2 260 0.05 Qt.. wc2 90 0 0.3 wc2 265 0 1.3 wc2 95 0 0.2 wc2 270 0 1.6 wc2 100 0 0.3 wc2 275 0.07 2 wc2 105 0 0.4 wc2 280 0.03 2.2 wc2 110 0 0.5 wc2 285 0.04 1.8 wc2 115 0 1 wc2 290 0 1.7 wc2 120 0 1 wc2 295 0.02 1.4 wc2 125 0 1.5 wc2 300 0 1.3 wc2 130 0 1.4 wc2 305 0 1.7 wc2 135 0 1.4 wc2 310 0.02 2.3 wc2 140 0 1 wc2 315 0.03 1.6 wc2 145 0 1.2 wc2 320 0 1 wc2 150 0 .,1 wc2 325 0.03 1.6 wc2 155 0 2.5 wc2 330 . 0 1.6 wc2 160 0 1.9 wc2 335 0 0.8 wc2 165 0 1.3 wc2 340 0 1 wc2 170 0 2.1 wc2 345 0 1.3 wc2 175 0 1.2 wc2 350 0.02 1.3 138

APPENDIX II ( con ' t )

DRILLHOLE WC-3

Sample Au Ag Sample Au Ag wc3 5 0.07 0.7 wc3 185 0.08 2.9 wc3 10 0.03 0.4 wc3 190 0.03 1.7 wc3 15 0 0 wc3 195 0.08 2.6 wc3 20 0 0 wc3 200 0.02 0.9 wc3 25 0 0 wc3 205 0 0.4 wc3 30 0.07 0.9 wc3 210 0 0 wc3 35 0.04 0.7 wc3 215 0 0.8 wc3 40 0.12 1.6 wc3 220 0.03 0.7 wc3 45 0.08 1.4 wc3 225 0.09 1.1 wc3 50 0.04 0.9 wc3 230 0 1 wc3 55 0.03 0.6 wc3 235 0.05 0.6 wc3 60 0.03 0.7 wc3 240 0.04 1.2 wc3 65 0 0.5 wc3 245 0.03 1.5 0 1 wc3 70 0 0.6 wc3 250 0 v..L. wc3 75 0.05 1 wc3 255 0 0.2 wc3 80 0 0 wc3 260 0.03 1 wc3 85 0.04 0.8 wc3 265 0.12 2.9 wc3 90 0.03 0.7 wc3 270 0.09 1.4 wc3 95 0.03 0.4 wc3 275 0.08 0.8 wc3 100 0 0.2 wc3 280 0.14 2 wc3 105 0.03 0.5 wc3 285 0.11 0.4 wc3 110 0.02 0.3 wc3 290 0 1.6 wc3 115 0.06 wc3 295 0.03 0.9 wc3 125 0.06 0.8 wc3 300 0.03 1.6 wc3 130 0 0.5 wc3 305 0 0.8 wc3 135 0 0.6 wc3 310 0 0.8 wc3 140 0 0.8 wc3 315 0 0.7 A wc3 145 0 0.2 wc3 320 v 0.9 wc3 150 0 0.2 wc3 325 0 1.1 wc3 155 0 0 wc3 330 0 0.8 wc3 160 0 0.5 wc3 335 0 0.7 wc3 165 0 0.8 wc3 340 0 1.5 wc3 170 0.03 1 wc3 345 0.03 1.3 wc3 175 0.03 0.9 wc3 350 0 1 wc3 180 0 0.8 139

APPENDIX II (con't)

DRILLHOLE WC-4

Sample Au Ag Sample Au Ag wc4 5 0.03 0.6 wc4 160 0 0 wc4 10 0.05 1.1 wc4 165 0.09 0 wc4 11 0 0.1 wc4 170 0.06 0 wc4 15 0.06 1.2 wc4 175 0.03 0 wc4 11 0.1 0 wc4 180 0.03 0 wc4 12 0.2 0 wc4 185 0.03 0.6 wc4 12 0.1 0 wc4 190 0.04 0.3 wc4 20 0.04 1 wc4 195 0 0.7 wc4 25 0.03 0.8 wc4 205 0 wc4 30 0.03 0.9 wc4 210 0 0 wc4 35 0 0 wc4 215 0 0 wc4 40 0 0.2 wc4 220 0 0 wc4 45 0 0.2 wc4 225 0 0 wc4 50 0 0 wc4 230 0 0 wc4 55 0 0.2 wc4 235 0 0 wc4 60 0 0.2 wc4 240 0 0 wc4 60 0 2.5 wc4 245 0 0 n wc4 65 0 0.3 wc4 250 0 y wc4 70 0 0.2 wc4 255 0 0 wc4 75 0.03 0.2 wc4 260 0 0 wc4 80 0.13 0.9 wc4 265 0 0 wc4 85 0.06 0.5 wc4 270 0 0 wc4 90 0 0.2 wc4 275 0 0 wc4 95 0 0 wc4 280 0.23 2.4 wc4 100 0 0 wc4 285 0.06 1.1 wc4 105 0.03 0.4 wc4 290 0.05 1 wc4 110 0.03 0 wc4 295 0 0 wc4 115 0.1 0 wc4 300 0 0 wc4 115 0.13 0.8 wc4 305 0 0 wc4 120 0.2 0 wc4 310 0 0 wc4 120 0.23 0.8 wc4 315 0 0 wc4 125 0.1 0 wc4 320 0 0 wc4 125 0.16 0.9 wc4 325 0 0 wc4 130 0.04 0 wc4 330 0 0 wc4 135 0.08 0.2 wc4 335 0 0 wc4 140 0.11 0.4 wc4 340 0 0 wc4 145 0.08 0.8 wc4 345 0 0 wc4 150 0 0 wc4 350 0 0 wc4 155 0 0 140

APPENDIX II ( con '1: )

DRILLHOLE WC-5

Sample Au Ag Sample Au Ag wc5 5 0 0.6 wc5 185 0 0 wc5 10 0 ,., wc5 190 0 0 wc5 15 0 1.4 wc5 195 0 0 wc5 20 0 1.1 wc5 200 0 0 wc5 r-,inm 0 1.5 wc5 205 0 0 wc5 30 0 1.9 wc5 210 0 0 wc5 35 0 1.5 wc5 215 0 0 wc5 40 0 2.1 wc5 220 0 0 wc5 45 0 1.2 wc5 225 0 0 wc5 50 0 1.3 wc5 230 0 0 wc5 55 0 1.9 wc5 235 0 0.5 wc5 60 0 2.1 wc5 240 0 1 0 wc5 65 0 y wc5 245 0 1.5 wc5 70 0 2.6 wc5 250 0 1.6 n A wc5 75 0 & . .s wc5 255 0 2.2 0 n0 n o wc5 85 0 G . -• wc5 260 0 c. . o n n wc5 90 0 c. . 4. wc5 265 0 2.4 wc5 95 0 1.8 wc5 270 0 1 wc5 100 0 2.7 wc5 275 0 1.3 n wc5 105 0 ,, wc5 280 0 1.4 wc5 110 0 ,,0 wc5 285 0 0.6 n n wc5 115 0 c, . L, wc5 290 0 0.3 wc5 120 0 1.7 wc5 295 0 0.3 wc5 125 0 2 wc5 300 0 0.4 wc5 130 0 1.7 wc5 305 0 0.4 wc5 135 0 1.6 wc5 310 0 0.4 wc5 140 0 1.9 wc5 315 0 0.3 n 0 wc5 145 0 2 wc5 320 0 V . 0 wc5 150 0 2.4 wc5 325 0 0.5 wc5 155 0 2.1 wc5 330 0 0.5 wc5 160 0 2.6 wc5 335 0 0.3 wc5 165 0 2.2 wc5 340 0 0.3 wc5 170 0 0.6 wc5 345 0 0.3 wc5 175 0 0 wc5 350 0 1.4 wc5 180 0 0 141

APPENDIX II (conit)

DRILLHOLE WC-6

Sample Au Ag Sample Au Ag wc6 5 0 0.8 wc6 180 0 0.5 wc6 10 0 0.9 wc6 185 0 0.7 wc6 15 0 0.8 wc6 190 0 0.6 wc6 20 0 1.2 wc6 195 0.04 0.6 wc6 25 0 1.4 wc6 200 0.03 0.6 wc6 30 0 1.6 wc6 205 0 0 wc6 35 0 1.4 wc6 210 0 0.5 wc6 40 0 1.9 wc6 215 0 0.4 0 0 wc6 45 0 ,u. wc6 220 0 0 0 0 wc6 50 0 ,‘,. wc6 225 0 0 n o wc6 55 0 4,- wc6 230 0.03 0 wc6 60 0 1.4 wc6 235 0.02 0 wc6 65 0 0.9 wc6 240 0 0.7 wc6 70 0 0.4 wc6 245 0 0 wc6 75 0 0.4 wc6 250 0 0 wc6 80 0 0.4 wc6 255 0 0.3 wc6 85 0 0.3 wc6 260 0 0.5 wc6 90 0 0.4 wc6 265 0 0.6 wc6 95 0 0.5 wc6 270 0 0.5 wc6 100 0 0.8 wc6 275 0 1.7 wc6 105 0.04 1 wc6 280 0 1 wc6 110 0.03 .,1 wc6 285 0 1 wc6 115 0 1 wc6 290 0 0.8 wc6 120 0 1 wc6 295 0 0.5 wc6 125 0 0.8 wc6 300 0 0.5 wc6=130 0 .,1 wc6 305 0 2.1 0 wc6 135 0 1 wc6 310 0 u wc6 140 0.02 1 wc6 315 0 .,1 wc6 145 0 1.1 wc6 320 0 1.1 wc6 150 0 1 wc6 325 0 0.5 wc6 155 0 1 wc6 330 0 1.9 wc6 160 0 1.1 wc6 335 0 1.7 wc6 165 0 1.2 wc6 340 0 1.1 wc6 170 0 0.8 wc6 345 0 1.7 wc6 175 0.05 0.7 wc6 350 0 1.6 142

APPENDIX II (con't)

DRILLHOLE WC - 7

Sample Au Ag Sample Au Ag wc7 5 0 1.6 wc7 180 0.12 1.3 wc7 10 0.04 1.1 wc7 185 0.2 1.1 wc7 15 0.07 1.5 wc7 190 0.36 2.5 wc7 20 0 1.6 wc7 195 0.09 1.6 wc7 25 0 1.4 wc7 200 0.12 1.2 wc7 30 0.07 1.8 wc7 205 0.11 0.7 wc7 35 0.03 2.4 wc7 210 0.05 0.7 wc7 40 0.2 3.5 wc7 215 0.09 0.5 wc7 45 0.19 2.6 wc7 220 0.05 1.3 0 0 wc7 50 0.06 L,,. , wc7 225 0.07 0.7 wc7 55 0.25 3.4 wc7 230 0.07 0.2 wc7 60 0.19 2.9 wc7 235 0.05 0.5 wc7 65 0.18 3.5 wc7 240 0.1 8.4 wc7 70 0.19 2.1 wc7 245 0.09 4 wc7 75 0.16 1.8 wc7 250 0 2.5 wc7 80 0.28 3.2 wc7 255 0.07 3.9 0 0 wc7 85 0.23 3.7 wc7 260 0.05 ..,0. wc7 90 0.23 2.9 wc7 265 0.13 2.3 wc7 95 0.25 2.7 wc7 270 0 2.5 wc7 100 0.27 2.9 wc7 275 0.14 2.3 wc7 105 0.24 2.5 wc7 280 0.11 6.4 wc7 110 0.09 2.2 wc7 285 0.1 10.1 wc7 115 0.06 1.9 wc7 290 0.17 10.6 0 n wc7 120 0.1 ...PC.. wc7 295 0.16 4.3 wc7 125 0.02 1.7 wc7 300 0.12 v' wc7 130 0.08 2 wc7 305 0.07 2.5 wc7 135 0.09 1.9 wc7 310 0.11 2.9 wc7 140 0.12 1.2 wc7 315 0.08 2.3 wc7 145 0.12 2.9 wc7 320 0.22 1.5 wc7 150 0.05 1.8 wc7 325 0.12 2.2 wc7 155 0.06 1.6 wc7 330 0.26 5.3 wc7 160 0.08 1.7 wc7 335 0.15 2.1 wc7 165 0.03 1 wc7 340 0.28 2.9 wc7 170 0.25 2.1 wc7 345 0.07 1.5 wc7 175 0.18 1.6 wc7 350 0.11 2.2 143

APPENDIX III

WHOLE ROCK ANALYSES

Whole Rock Analyses, WC drill holes.

Major elements reported as weight % oxides. Trace elements reported as ppm. See Table 5-1 for analytical methods. DRILL HOLE WC-1

Samp DEPTH Au 8102 AL203 CaO MgO Na20 K20 Fe203 MnO WC1 10 10 0 68.3 12.2 0.86 0.51 1.82 5.58 6.83 0.06 WC1 25 25 0 63.7 13.8 1.27 0.77 2.31 6.12 7.62 0.09 WC1 50 50 0.52 64.4 12.8 0.8 1.54 0.13 2.47 9.19 0.25 WC1 90 90 0.15 68.2 11.4 0.38 0.65 0.42 5.61 5.67 <.01 WC1 110 110 0.17 73 9.79 0.35 0.54 0.94 4.9 5.97 <.01 WC1 135 135 0 68.3 12.1 0.19 0.29 1.5 7.44 6.18 0.01 WC1 160 160 0.03 70.8 12 0.28 0.32 1.46 7.35 4.15 0.01 WC1 200 200 0 69.7 12.2 0.48 0.52 1.83 6.6 4.87 0.01 WC1 230 230 0.26 74.1 11.6 0.33 0.3 1.59 6.98 1.88 0.02 WC1 280 280 0.23 72.8 12.1 0.33 0.24 1.82 7.16 2.55 <.01 WC1 325 325 0.14 72.6 12.1 0.47 0.37 1.94 6.39 2.57 <.01 avg 0.14 69.63 12.01 0.52 0.55 1.43 6.05 5.23 0.04 s.d. 0.15 3.30 0.92 0.31 0.35 0.64 1.37 2.18 0.07 n=11

Samp TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WC1 10 0.8 0.21 0.01 240 380 50 360 30 1910 WC1 25 0.92 0.24 <.01 260 220 60 400 30 1710 WC1 50 0.79 0.17 <.01 130 480 70 440 30 2020 WC1 90 0.71 0.14 <.01 230 230 40 380 30 1970 WC1 110 0.66 0.1 0.01 220 180 50 310 40 1560 WC1 135 0.7 0.14 0.01 290 110 50 380 30 1640 WC1 160 0.65 0.1 0.01 290 150 50 360 40 1620 WC1 200 0.69 0.14 <.01 280 150 60 370 20 1740 WC1 230 0.67 0.05 0.01 280 160 30 350 30 1840 WC1 280 0.64 0.08 0.01 290 210 50 360 30 2060 WC1 325 0.68 0.06 <.01 260 240 30 410 40 1900 avg 0.72 0.13 0.01 252 228 49 375 32 1815 s.d. 0.08 0.06 0.00 45 105 12 JO 6 163 n=11 144

APPENDIX III (can't)

DRILL HOLE WC-2

SAND DEPTH Au S 1 02 AL203 Ca0 MgO Na20 1(20 Fe203 MnO WC2 15 15 0 66.1 12.7 0.49 0.63 1.59 7.05 7.76 0.05 WC2 50 50 0.06 70.1 10.6 0.56 0.78 0.35 6.83 6.79 0.02 WC2 60 60 0 71.6 10.7 0.48 1.08 0.25 7.12 4.99 0.03 WC2 80 80 0.05 80.3 6.71 0.22 0.68 0.08 1.69 5.6 0.01 WC2 105 105 0 79.6 9.07 0.11 0.71 0.02 1.67 4.08 <.01 WC2 140 140 0 90.3 4.02 0.07 0.16 0.01 0.54 1.3 <.01 WC2 165 165 0 90.5 3.5 0.18 0.12 0.09 0.43 1.2 <.01 WC2 220 220 0 89.5 4.75 0.04 0.14 <.01 0.51 2.01 <.01 WC2 280 280 0.05 92.2 2.83 0.03 0.1 <.01 0.25 1.67 <.01 WC2 315 315 0.03 93.2 2.22 0.06 0.18 0.03 0.36 0.99 <.01 WC2 345 345 0 91.5 2.86 0.13 0.34 0.04 0.62 1.37 <.01 Avg 0.02 83.17 6.36 0.22 0.45 0.22 2.46 3.43 0.01 s.d. 0.02 9.60 3.60 0.19 0.32 0.45 2.82 2.38 0.02 n=11

SAND TiO2 P205 Cr203 Rb Sr Y Zr Nb Ea WC2 15 0.74 0.18 <.01 320 130 60 410 30 1650 WC2 50 0.59 0.18 0.01 330 100 30 310 30 1530 WC2 60 0.64 0.18 <.01 340 60 50 320 10 1720 WC2 80 0.48 0.17 0.01 120 20 20 270 30 470 WC2 105 0.54 0.13 0.01 110 <10 20 370 10 500 WC2 140 0.24 0.14 0.03 30 30 20 30 10 570 WC2 165 0.2 0.36 0.03 20 <10 20 20 20 530 WC2 220 0.27 0.11 0.02 30 10 20 30 <10 500 WC2 280 0.19 0.32 0.03 10 70 20 10 10 940 WC2 315 0.14 0.17 0.03 20 110 20 10 <10 1880 WC2 345 0.17 0.12 0.05 50 90 10 20 10 630 Avg 0.38 0.19 0.02 125 56 26 164 15 993 s.d. 0.21 0.08 0.01 130 45 14 161 11 550

DRILL HOLE WC-3 SAW' DEPTH Au S 1 02 AL203 CaO MgO Na20 1(20 Fe203 MnO WC3 15 15 0.03 66.4 12.4 1.08 1.6 0.69 3.12 7.28 0.02 WC3 45 45 0.1 77.9 7.96 0.11 0.4 0.2 3.57 3.93 <.01 WC3 70 70 0 75.8 9.72 0.12 0.36 0.27 3.51 5.13 <.01 WC3 110 110 0.03 69.1 11.4 0.09 0.12 0.47 5.53 5.2 <.01 WC3 160 160 0 76.7 10.5 0.07 0.31 0.14 3.29 4.58 0.02 WC3 210 210 0 75.2 9.64 0.11 0.61 0.12 4.26 6.42 <.01 WC3 240 240 0.05 74.3 11.3 0.13 0.6 0.08 1.93 5.7 0.01 WC3 255 255 0 74.2. 9.85 0.26 1.12 0.12 4.26 4.41 0.04 WC3 285 285 0.15 83.5 5.63 0.17 0.51 0.04 1.97 3.65 0.03 WC3 300 300 0.03 92.9 3.6 0.11 0.34 <.01 0.88 0.89 0.01 WC3 340 340 0 85.8 4.71 0.2 0.43 0.07 1.15 1.52 <.01 Avg 0.04 77.44 8.79 0.22 0.58 0.20 3.04 4.43 0.01 s.d. 0.05 7.17 2.80 0.28 0.40 0.20 1.36 1.83 0.01 n=11 145

APPENDIX III (con't)

SAMP TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WC3 15 0.67 0.19 <.01 260 130 50 350 40 850 WC3 45 0.47 0.12 0.02 190 30 40 240 20 1040 WC3 70 0.65 0.15 <.01 180 40 50 380 30 1190 WC3 110 0.65 0.18 0.02 220 40 40 330 30 1620 WC3 160 0.66 0.14 <.01 190 40 60 350 20 1450 WC3 210 0.64 0.13 <.01 270 20 30 330 20 1440 WC3 240 0.68 0.12 0.01 180 30 60 360 30 1180 WC3 255 0.61 0.14 <.01 280 30 40 300 20 1880 WC3 285 0.43 0.13 0.02 140 40 10 50 10 850 WC3 300 0.23 0.08 0.04 <10 60 <10 50 30 800 WC3 340 0.26 0.16 0.02 90 50 20 40 10 500 Avg 0.54 0.14 0.01 182 46 36 253 24 1164 '10 s.d. 0.16 0.03 0.01 79 Qt.) 19 131 9 389

DRILL HOLE WC-4

SAMP DEPTH Au S 1 02 AL203 Ca0 MgO Na20 K20 Fe203 MnO WC4 15 15 0.05 68 11.4 0.71 0.23 1.17 4.5 6.79 0.01 WC4 45 45 0 64 12.9 1.31 1.21 2.25 5.65 8.14 0.08 WC4 85 85 0.1 67.2 12.2 0.54 0.41 1.62 6.52 7.08 0.07 WC4 100 100 0 65.2 13.2 0.79 0.73 1.88 6.23 6.87 0.05 WC4 120 120 0.17 69.3 11.7 0.46 0.53 1.06 6.87 5.59 0.04 WC4 170 170 0.08 78 8.24 0.51 0.8 0.43 3.55 3.12 0.01 WC4 210 210 0 70.5 11 0.52 1.02 0.6 5.5 5.26 <.01 WC4 250 250 0 66.5 13.1 0.53 0.43 1.57 7.97 6.14 0.02 WC4 285 285 0.15 68.5 12.6 0.51 0.53 1.91 6.67 4.37 0.02 WC4 315 315 0 68.5 12.5 0.59 0.56 1.95 6.3 5.28 0.02 WC4 335 335 0 66.9 12.8 1.01 0.63 1.99 6.27 5.8 0.04 Avg 0.05 68.42 11.97 0.68 0.64 1.49 6.00 5.86 0.03 s.d. 0.06 3.50 1.36 0.25 0.27 0.57 1.14 1.32 0.02 n=11

SAMP TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WC4 15 0.74 0.26 0.01 180 230 60 330 40 1570 WC4 45 0.83 0.25 <.01 270 190 50 370 40 1830 WC4 85 0.8 0.16 0.01 310 220 50 360 40 1970 WC4 100 0.88 0.2 <.01 290 290 40 410 30 1690 WC4 120 0.77 0.13 <.01 360 190 50 340 30 1670 WC4 170 0.48 0.07 <.01 200 120 40 230 30 940 WC4 210 0.56 0.08 <.01 340 160 50 310 30 1830 WC4 250 0.68 0.17 <.01 340 90 40 400 30 1800 WC4 285 0.63 0.11 0.01 280 200 50 380 30 1790 WC4 315 0.66 0.12 (.01 270 140 40 400 40 1760 WC4 335 0.66 0.16 <.01 270 160 50 410 30 1890 no", Avg 0.70 0.16 0.00 WOO 181 47 358 34 1704 s.d. 0.11 0.06 0.00 53 53 6 52 5 263 146

APPENDIX III (con't)

DRILL HOLE WC-5

Samp DEPTH Au S 1 02 AL203 CaO MgO Na2o K20 Fe203 MnO WC5 15 15 0 84.9 5.24 1.25 0.62 0.54 0.84 2.34 0.03 WC5 50 50 0 84.2 5.56 0.77 0.7 0.32 1.4 2.39 0.01 WC5 105 105 0 91.5 2.4 0.04 0.24 <.01 0.67 1.59 <.01 WC5 150 150 0 91.4 1.68 0.45 0.33 0.03 0.38 1.59 <.01 WC5 195 195 0 93 2.42 0.02 0.22 <.01 0.56 1.24 <.01 WC5 250 250 0 87.4 3.14 0.05 0.32 0.02 0.77 2.36 <.01 WC5 300 300 0 92.4 2.57 0.02 0.25 0.02 0.6 0.97 <.01 WC5 350 350 0 89.5 3.65 0.06 0.36 0.03 0.87 1.23 <.01 Avg 0 89.29 3.33 0.33 0.38 0.12 0.76 1.71 0.01 s.d. 0 3.19 1.31 0.43 0.17 0.19 0.28 0.54 0.01 n=8

Samp TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WC5 15 0.35 0.18 0.03 30 210 30 60 20 860 WC5 50 0.32 0.31 0.02 70 330 50 110 20 890 WC5 105 0.14 0.29 0.03 40 <10 <10 60 <10 410 WC5 150 0.09 0.27 0.05 20 30 10 10 10 330 WC5 195 0.15 0.06 0.06 40 40 <10 60 20 370 WC5 250 0.18 0.18 0.04 40 <10 10 70 10 400 WC5 300 0.15 0.06 0.04 50 10 20 70 30 320 WC5 350 0.19 0.12 0.03 50 <10 10 100 <10 370 Avg 0.20 0.18 0.04 43 78 16 68 14 494 s.d. 0.09 0.09 0.01 14 116 16 28 10 222

DRILL HOLE WC-6

SAMP DEPTH Au S 1 02 AL203 CaO MgO Na20 1(20 Fe203 MnO WC6 15 15 0 88.9 3.53 1.19 0.45 0.22 0.45 1.06 0.01 WC6 65 65 0 68.3 10.2 4.76 2.18 2.03 1.43 6.82 0.11 WC6 110 110 0.04 67.2 12.4 1.45 1.61 0.48 2.76 5.15 0.04 WC6 165 165 0 66.1 13.1 1.64 1.74 0.15 3.46 5.23 0.03 WC6 200 200 0.04 65.2 11.1 3.25 2.22 0.24 2.19 4.35 0.1 WC6 235 235 0.03 43.1 12.3 8.77 4.05 0.3 1.5 7.91 0.15 WC6 265 265 0 69.1 10.2 1.66 1.83 0.24 2.81 4.37 0.13 WC6 295 295 0 89.8 4.28 0.12 0.51 <.01 1.04 1.04 <.01 WC6 350 350 0 89.8 3.82 0.1 0.39 0.04 1.38 1.07 <.01 Avg 0.01 71.94 8.99 2.55 1.66 0.41 1.89 4.11 0.06 s.d. 0.02 14.46 3.74 2.60 1.09 0.59 0.92 2.41 0.06 n=9 147

APPENDIX III (con't)

DRILL HOLE WC-6

SAMP TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WC6 15 0.21 0.13 0.03 30 160 <10 60 10 660 WC6 65 0.92 0.44 0.01 60 330 40 120 20 940 WC6 110 0.66 0.39 0.01 120 110 30 210 10 1200 WC6 165 0.63 0.41 0.01 160 80 50 180 20 740 WC6 200 0.59 0.28 0.01 110 80 10 180 30 740 WC6 235 0.82 0.27 (.01 90 90 <10 90 10 880 WC6 265 0.59 0.28 0.02 130 100 30 140 10 1330 WC6 295 0.21 0.05 0.02 90 70 20 90 10 400 WC6 350 0.19 0.08 0.03 80 40 <10 140 <10 550 Avg 0.54 0.26 0.02 97 118 20 134 13 827 s.d. 0.26 0.14 0.01 37 81 18 47 8 281

DRILL HOLE WC-7

Samp DEPTH Au S 1 02 AL203 CaO MgO Na20 K20 Fe203 MnO WC7 25 25 0 79.4 6.12 1.09 0.38 0.25 1.16 5.27 <.01 WC7 45 45 0.2 87.2 4.45 0.17 0.33 0.2 1.72 2.67 0.01 WC7 95 95 0.24 83.3 5.76 0.06 0.18 0.18 2.2 4.73 0.01 WC7 130 130 0.05 89.7 3.17 0.16 0.2 0.05 1.34 1.99 0.07 WC7 155 155 0.06 78.2 7.29 0.1 0.34 0.32 4.14 5.4 0.04 1 C7 190 190 0.28 87.1 4.19 0.04 0.1 0.03 0.11 4.17 0.01 WC7 255 255 0.03 81.1 8.43 0.12 0.22 0.06 0.11 4.01 0.01 WC7 290 290 0.14 85.4 4.78 0.23 0.4 0.06 0.14 2.86 0.02 WC7 335 335 0.21 82.6 6.34 0.2 0.29 0.19 3.71 2.48 <.01 WC7 350 350 0.07 82.3 6.64 0.16 0.2 0.22 3.22 3.12 <.01 avg 0.13 33.63 5.72 0.23 0.26 0.16 1.79 3.67 0.02 s.d. 0.09 3.49 1.50 0.29 0.09 0.09 1.43 1.15 0.02 n=10

Samp TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WC7 25 0.35 0.25 0.02 60 190 20 100 10 440 WC7 45 0.37 0.08 0.03 120 100 <10 80 30 660 WC7 95 0.56 0.09 0.03 130 100 20 70 <10 900 WC7 130 0.28 0.05 0.04 90 60 20 30 20 880 WC7 155 0.59 0.08 0.02 270 80 30 140 10 1410 WC7 190 0.31 0.06 0.03 20 80 10 80 30 880 WC7 255 0.49 0.09 0.03 10 210 30 160 30 930 WC7 290 0.44 0.06 0.03 10 260 20 100 20 1720 WC7 335 0.57 0.1 0.03 230 180 20 120 20 1600 WC7 350 0.59 0.14 0.02 180 250 40 110 20 1270 avg 0.46 0.10 0.03 112 151 21 99 19 1069 s.d. 0.11 0.06 0.01 87 71 10 35 9 393 148

APPENDIX IV

BASELINE SAMPLE ANALYSES

VALMY FORMATION

Ov surface samples

San p Au S102 AL203 CaO MgO Na20 K20 Fe203 MriO WRA-V1 88.1 5.09 0.07 0.49 0.07 1.25 1.15 <.01 WRA-V2 90.5 3.35 0.15 0.23 0.08 1.14 1.21 <.01 82-079 0 92.4 3.09 0.19 0.15 0.01 1.91 0.61 0.01 82-204 0.06 80.4 7.79 0.03 0.32 0.09 3.18 2.05 0.01 82-206 0.05 91.7 2.13 0.05 0.13 0.06 0.55 1.11 <.01 Avg 88.6 4.29 0.10 0.26 0.06 1.61 1.23 0.00 s.d. 4.4 1.99 0.06 0.13 0.03 0.90 0.46 0.00

Ov, highly altered

82-069 0 86.6 7.84 0.53 0.17 0.13 0.74 0.63 <.01 82-078 0 93.3 3.71 0.5 0.06 0.05 0.24 0.44 <.01 avg 90.0 5.78 0.52 0.12 0.09 0.49 0.54 0 s.d. 3.3 2.06 0.02 0.06 0.04 0.25 0.09 0

Ov surface samples

Sang TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WRA-V1 0.26 0.05 0.01 60 <10 <10 120 30 710 WRA-V2 0.14 0.08 0.04 60 70 20 180 10 630 82-079 0.19 0.1 0.04 80 20 20 360 <10 660 82-204 0.38 0.1 0.02 160 10 10 110 20 640 82-206 0.21 0.07 0.09 10 80 <10 80 30 570 Avg 0.24 0.08 0.04 74 36 10 170 18 642 s.d. 0.08 0.02 0.03 49 33 9 100 12 45

Ov, highly altered

82-069 0.38 0.07 0.01 60 420 <10 80 10 690 82-078 0.18 0.04 0.03 30 40 10 210 10 270 avg 0.28 0.06 0.02 45 230 5 145 10 480 s.d. 0.1 0.02 0.01 15 190 5 65 0 210 149

APPENDIX IV (con't)

DACITE Td fresh Samp Au S102 AL203 CaO MgO Na20 K20 Fe203 MnO T-9 62.7 13.4 1.84 1.35 3.02 4.86 9.02 0.12 T18-a 64.5 13.7 2.61 0.52 3.52 4.54 8.27 0.10 Td aphanitic 62.3 13.94 3.35 0.93 3.45 4.40 8.70 0.15 Td porphyry 66.6 13.37 1.9 0.91 3.11 4.68 6.82 0.04 Avg 64.0 13.60 2.43 0.93 3.28 4.62 8.20 0.10 s.d. 1.7 0.23 0.61 0.29 0.21 0.17 0.84 0.04

Td altered T-3 68.6 14.5 0.63 0.33 2.09 5.49 3.24 <.01 T-5 63.9 13.5 0.87 0.67 2.07 6.15 7.96 0.02 82-173 0 64.6 13.7 0.87 0.82 1.85 6.22 7.45 0.02 avg 65.7 13.9 0.79 0.61 2.00 5.95 6.22 0.01 s.d. 2.07 0.43 0.11 0.20 0.11 0.33 2.12 0.01

Td highly altered 82-176 0 79.4 8.58 0.41 0.26 0.54 4.77 2.51 <.01 82-179 0 69 14.4 0.48 0.15 1.22 8.37 1.88 <.01 82-198 0 71.3 11.7 0.35 0.13 0.14 6.1 1.20 <.01 82-220 0.03 71.2 12.1 0.30 0.25 0.67 8.66 3.39 0.01 avg 72.7 11.7 0.39 0.20 0.64 6.98 2.25 0.00 s.d. 3.96 2.07 0.07 0.06 0.39 1.61 0.81 0.00

Td fresh Samp TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba T-9 0.88 0.25 <.01 170 260 60 390 50 1740 T18-a 0.87 0.24 <.01 160 310 50 400 30 1700 Td aphan 0.91 0.22 254 296 1700 Td porp 0.78 0.17 169 296 1430 Avg 0.86 0.22 0 165 248 55 346 40 1643 s.d. 0.05 0.03 0 5 51 5 50 10 124

Td altered T-3 0.93 0.14 <.01 210 340 60 390 40 1830 T-5 0.88 0.25 <.01 290 190 • 60 380 20 1520 82-173 0.90 0.24 0.01 290 170 50 390 20 1820 avg 0.90 0.21 0.00 263 233 57 387 27 1723 s.d. 0.02 0.05 0.00 38 76 5 5 9 144

Td highly altered 82-176 0.5 0.1 0.02 230 160 140 220 20 1030 82-179 0.76 0.38 <.01 330 280 50 380 40 2280 82-198 0.58 0.23 0.01 250 90 50 290 20 960 82-220 0.75 0.11 <.01 390 150 40 320 30 2220 avg 0.65 0.21 0.01 300 170 70 303 28 1623 s.d. 0.11 0.11 0.01 64 69 41 58 8 628 150

APPENDIX IV (con't)

Baseline whole-rock analyses

CHALCEDONY VEIN

San p Au S102 AL203 CaO MgO Na20 K20 Fe203 T-1 77.7 7.75 0.19 0.19 0.24 5.32 5.08 0.03 82-200 88.9 4.17 0.28 0.13 0.07 3.12 0.92 <.01 avg 83.3 5.96 0.24 0.16 0.16 4.22 3.00 0.02

Sang TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba T-1 0.54 0.09 0.02 310 100 30 180 30 1050 82-200 0.38 0.1 0.02 190 20 20 110 20 640 avg 0.46 0.10 0.02 250 60 25 145 25 845

BASALT

Samp Au Si02 AL203 CaO MgO Na20 K20 Fe203 Mh0 WRA-Tba 55.9 13.3 6.86 2.75 2.97 2.43 11.5 0.16

Samp TiO2 P205 Cr203 Rb Sr Y Zr Nb Ba WRA-Tba 1.62 0.67 <.01 80 340 40 190 40 770 151

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