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Epithermal Gold Deposits-Paf! I "k AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY Instructions on ordering publications of the U.S. Geological Survey, along w1th pnces of the last offenngs, are given m the cur rent-year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Pnces of available U.S. Geologtcal Sur vey publications released pnor to the current year are hsted m the most recent annual "Pnce and Availab1hty LISt" Pubhcations that are hsted m vanous U.S. Geological Survey catalogs (see back inside cover) but not liSted m the most recent annual "Pnce and Availability List" are no longer avmlable. Pnces of reports released to the open files are gtven m the hsung "U.S. Geological Survey Open-File Reports," updated month ly, which IS for salem microfiche from the U.S. Geological Survey, Books and Open-File Reports Section, Federal Center, Box 25425, Denver, CO 80225. 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BY MAIL OVER THE COUNTER Books Books Professional Papers, Bulletms, Water-Supply Papers, Techruques of Water-Resources Investtgattons, Crrculars, pubhcattons of general m Books of the U S Geological Survey are avmlable over the terest (such as leaflets, pamphlets, booklets), smgle copies of Earthquakes counter at the followmg Geological Survey Pubhc Inqumes Offices, all & Volcanoes, Prehmmary Determmauon of Epicenters, and some nus of whlch are authonzed agents of the Supermtendent of Documents cellaneous reports, mcludmg some of the foregomg senes that have gone out of pnnt at the Supenntendent of Documents, are obtamable by mall from • WASHINGTON, D.C --Main lntenor Bldg , 2600 comdor, 18th and C Sts , NW U.S. Geological Survey, Books and Open-File Reports • DENVER, Colorado--Federal Bldg , Rm 169, 1961 Stout St. Federal Center, Box 25425 • LOS ANGELES, California--Federal Bldg , Rm 7638, 300 N Denver, CO 80225 Los Angeles St. • MENLO PARK, California--Bldg 3 (Stop 533), Rm. 3128, Subscnpuons to penochcals (Earthquakes & Volcanoes and 345 Middlefield Rd Prehmmary Determmatlon of Epicenters) can be obtamed ONLY from • RESTON, Vlrglnla--503 National Center, Rm 1C402, 12201 the Sunnse Valley Dr • SALT LAKE CITY, Utah--Federal Bldg., Rm. 8105, 125 Superintendent of Documents South State St. Government Printing Office • SAN FRANCISCO, California--Customhouse, Rm 504, 555 Washington, D.C. 20402 Battery St • SPOKANE, Washlngton--U S Courthouse, Rm. 678, West (Check or money order must be payable to Supenntendent of Docu 920 Riverside Ave . ments.) • ANCHORAGE, Alaska--Rm. 101, 4230 Uruversny Dr. • ANCHORAGE, Alaska--Federal Bldg, Rm E-146, 701 C St Maps For maps, address mall orders to U.S. Geological Survey, Map Distribution Maps Federal Center, Box 25286 Maps may be purchased over the counter at the U S. Geologl Denver, CO 80225 cal Survey offices where books are sold (all addresses m above hst) and at the followmg Geological Survey offices Residents of Alaska may order maps from • ROLLA, Mlssourl--1400 Independence Rd Alaska Distribution Section, U.S. Geological Survey, • DENVER, Colorado--Map Distnbutton. Bldg 810, Federal New Federal Building - Box 12 Center 101 Twelfth Ave., Fairbanks, AK 99701 • FAIRBANKS, Alaska--New Federal Bldg, 101 Twelfth Ave Chapter H Epithermal Gold Deposits-Part I The Goldfield Gold District, Esmeralda and Nye Counties, Nevada By ROGER P. ASH LEY The Tonopah Precious-metal District, Esmeralda and Nye Counties, Nevada By ROGER P. ASH LEY The Republic Gold District, Ferry County, Washington By MORTIMER H. STMTZ and ROBERT C. PEARSON The Comstock Lode Precious-metal District, Washoe and Storey Counties, Nevada By WILLIAM C. BAGBY and ROGER P. ASH LEY U.S. GEOlOGICAl SURVEY BUllETIN 1857 GEOLOGY AND RESOURCES OF GOLD IN THE UNITED STATES DANIEL R. SHAWE and ROGER P. ASHLEY, SCientific Editors LM.H. CARTER, Techmcal Editor DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names 1n th1s publication IS for descnpt1ve purposes only and does not 1mply endorsement by the U S Government UNITED STATES GOVERNMENT PRINTING OFFICE 1990 For sale by the Books and Open-F1Ie Reports Section U.S. Geological Survey Federal Center Box 25425 Denver, CO 80225 Library of Congress Cataloging-In-Publication Data Ep1thermal gold deposits p em -(Geology and resources of gold 1n the Umted States , ch H ) (US Geolog1cal Survey bulletin, 1857H) Includes b1bhograph1cal references Supt of Docs no I 19 3 1857H 1 Gold ores-Nevada 2 Gold ores-Wash1ngton-Ferry County 3 Hydrothermal deposits-Nevada 4 Hydrothermal depos1ts-Wash1ngton-Ferry County I Geologrcal Survey (US) II Senes Ill Senes U S Geologrcal Survey bulletrn , 1857H QE75 89 no 1857-H [TN423 N3) 557 3 s-dc20 90-3011 (553 4'1'09793] CIP CONTENTS The Goldfield gold district, Esmeralda and Nye Counties, Nevada Abstract Hl Introduction Hl Geologic setting H2 Characteristics of ore bodies HS Conclusions H6 References cited H6 The Tonopah precious-metal district, Esmeralda and Nye Counties, Nevada ~ Abstract H8 Introduction H8 Geologic setting H9 Characteristics of ore bodies H11 Conclusions HU References cited HU The Republic gold district, Ferry County, Washington Abstract H14 Introduction H14 Geologic setting HIS O'Brien Creek Formation H1S Sanpoil Volcanics H16 Scatter Creek Rhyodacite H17 Klondike Mountain Formation H17 Ore deposits Hl8 References cited H20 The Comstock Lode precious-metal district, Washoe and Storey Counties, Nevada Abstract H21 Introduction H21 Geologic setting H24 Stratigraphy H24 Structure H26 Alteration H26 Contents Ill Age relations H27 Ore deposits H27 Conclusions H29 References cited H30 FIGURES Hl. Index map showing locations of the Goldfield and Tonopah mming districts, Nevada Hl H2-5. Maps showing: H2. Generalized geology of the Goldfield mining district, Nevada H3 H3. Hydrothermally altered and ore-bearing areas of the Goldfield mming district H4 H4. Generalized geology of the Tonopah minmg district, Nevada H9 H5. Generalized geology of the Republic graben, Ferry County, Washington H16 H6 Index map showing the mines of the Republic mining district, Washington H19 H7. Map showing location of the Comstock Lode district in western Nevada H21 H8. Geologic map of the area of the Comstock Lode H22 H9. K20-variation diagram for samples from the Alta and Kate Peak Formations H2S HlO. Longitudinal section projecting major ore bodies in the Comstock Lode onto the plane of the Comstock fault H28 Hll. Schematic cross section of the Comstock Lode at the Consolidated Virginia bonanza H29 TABLE Hl. Potassium-argon ages for rocks and vein minerals in the Comstock Lode district H2S IV Contents GEOLOGY AND RESOURCES OF GOLD IN THE UNITED STATES Epithermal Gold Deposits-Part I The Goldfield Gold District, Esmeralda and Nye Counties, Nevada By Roger P. Ashley 0 0 Abstract 12r0_________~1~18~ 0 _________1~16~ ---------;11.4o The Goldfield district is an epithermal prec1ous metal depos1t of the quartz-alunrte type. Gold ore bod1es are assoc1ated spatially and temporally wrth a calc-alkalic vol canic center of earty M1ocene age Flows, tuffs, and brecc1as of this center overtap a small caldera of Oligocene age SiliCIC domes of Oligocene age and porphyritiC rhyodacite domes of earty M1ocene age both 1ntrude the caldera nng-fracture zone. Most of the rocks in and around the caldera are hydrothermally altered, and gold ore bod1es are clustered along the caldera marg1n, hosted both by Oligocene rocks N E V A D A cut by the ring-fracture zone and M1ocene rocks that 1ntrude or overtle the ring-fracture zone. The ore bodies formed at relatively shallow depths from meteonc water at about 200 to 300 °C. The d1strict has produced more than 4 2 mllhon ounces (130 metnc tons) of gold and 1 45 million ounces (45 metnc tons) of sliver, mostly before Wortd War I, and has modest TONOPAH reserves and inferred resources of gold M1nor intermittent production continues. INTRODUCTION The Goldfield mining district is located in the western part of the Basin and Range province, 250 km northwest of Las Vegas, Nev., and 300 km southeast of Reno, Nev. (fig. H1 ). It is 40 km south of Tonopah, site of another precious metal district described in a separate 0 100 200 KILOMETERS article. Gold was discovered in the northwestern part of the Goldfield district in 1902. The first of the major lodes Figure H1 locations of the Goldf1eld and Tonopah m1ning in the southwestern part of the district was discovered distncts, Nevada. about 6 months later, in June 1903. Production began late in 1903, and new mines were developed rapidly Manuscnpt approved for pubhcatton September 13, 1989 through 1904. The operations of all the major mines Epithermal Gold Deposits-Part I H1 except the Florence mine were consolidated as the The Goldfield deposit is an epithermal bonanza of Goldfield Consolidated Mines Company in late 1906. the enargite-gold or quartz-alunite type (Berger, 1986). Local mills were opened and expanded from 1905 to Such deposits occur in calc-alkalic volcanic rocks, are 1909, rail connections were completed in 1905 and 1907, associated with the effects of intense acid-sulfate hydro and a 48-km water-supply pipeline was completed from thermal alteration, and typically have significant byprod uct copper. Other examples in the United States include Lida, Nev., in 1907. Peak annual production came in Summitville, Colorado; Red Mountain, near Ouray, 1910, and production was small after 1919. Total Colorado; and the Pyramid, Peavme, and Wedekind recorded production is 4.19 million oz (130 metric tons) districts near Reno, Nevada Prominent examples else of gold, 1.45 million oz (45 metric tons) of silver, and 7 67 where m the world include El Indio, Chile; Chinkuash1h, million lb (3,420 metric tons) of copper.