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Ages of Selected Intrusive Rocks Ana Associated Ore Deposits in the Colorado Mineral Belt

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Ages of Selected Intrusive Rocks ana Associated Ore Deposits in the Colorado Mineral Belt U.S. GEOLOGICAL SURVEY BULLETIN 2109 AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given in the current- year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological Survey publica­ tions released prior to the current year are listed in the most recent annual "Price and Availability List." Publications that may be listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price and Availability List" may be no longer available. Reports released through the NTIS may be obtained by writing to the National Technical Information Service, U.S. Department of Commerce, Springfield, VA 22161; please include NTIS report number with inquiry. Order U.S. Geological Survey publications by mail or over the counter from the offices given below. BY MAIL OVER THE COUNTER Books Books and Maps Professional Papers, Bulletins, Water-Supply Papers, Tech­ Books and maps of the U.S. Geological Survey are available niques of Water-Resources Investigations, Circulars, publications over the counter at the following U.S. Geological Survey offices, of general interest (such as leaflets, pamphlets, booklets), single all of which are authorized agents of the Superintendent of copies of Earthquakes & Volcanoes, Preliminary Determination of Documents: Epicenters, and some miscellaneous reports, including some of the foregoing series that have gone out of print at the Superintendent of Documents, are obtainable by mail from ANCHORAGE, Alaska Rm. 101,4230 University Dr. LAKEWOOD, Colorado Federal Center, Bldg. 810 U.S. Geological Survey, Information Services MENLO PARK, California Bldg. 3, Rm. 3128, 345 Box 25286, Federal Center, Denver, CO 80225 Middlefield Rd. Subscriptions to periodicals (Earthquakes & Volcanoes and RESTON, Virginia USGS National Center, Rm. 1C402, Preliminary Determination of Epicenters) can be obtained ONLY 12201 Sunrise Valley Dr. from the SALT LAKE CITY, Utah Federal Bldg., Rm. 8105, 125 Superintendent of Documents South State St. Government Printing Office SPOKANE, Washington U.S. Post Office Bldg., Rm. 135, Washington, DC 20402 West 904 Riverside Ave. WASHINGTON, D.C. Main Interior Bldg., Rm. 2650,18th (Check or money order must be payable to Superintendent of and C Sts., NW. Documents.) Maps Maps Only Maps may be purchased over the counter at the following For maps, address mail orders to U.S. Geological Survey offices: U.S. Geological Survey, Information Services Box 25286, Federal Center, Denver, CO 80225 Residents of Alaska may order maps from FAIRBANKS, Alaska New Federal Bldg., 101 Twelfth U.S. Geological Survey, Earth Science Information Center Ave. 101 Twelfth Ave. - Box 12 ROLLA, Missouri 1400 Independence Rd. Fairbanks, AK 99701 STENNIS SPACE CENTER, Mississippi Bldg. 3101 Ages of Selected Intrusive Rocks and Associated Ore Deposits in the Colorado Mineral Belt By Charles G. Cunningham, Charles W. Naeser, Richard F. Marvin, Robert G. Luedke, and Alan R. Wallace U.S. GEOLOGICAL SURVEY BULLETIN 2109 Sixty-three fission-track and K-Ar age determinations help understand the temporal and spatial evolution of the Colorado Mineral Belt UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1994 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY GORDON P. EATON, Director For sale by U.S. Geological Survey, Information Services Box 25286, Federal Center, Denver, CO 80225 Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Published in the Eastern Region, Reston, Va. Manuscript approved for publication August 2, 1994. Library of Congress Cataloging in Publication Data Ages of selected intrusive rocks and associated ore deposits in the Colorado Mineral Belt / by Charles G. Cunningham ... [et al.]. p. cm. (U.S. Geological Survey bulletin ; 2109) Includes bibliographical references. Supt.ofDocs.no.:! 19.3:2109 1. Rocks, Igneous Colorado. 2. Intrusions (Geology) Colorado. 3. Radiocarbon dating Colorado. 4. Ore deposits Colorado. I. Cunningham, Charles G. II. Series. QE75.B9 no. 2109 [QE461] 557.3 s dc20 [553'.1'09788] 94-32991 CIP CONTENTS Abstract........................................................................................................................... 1 Introduction..................................................................................................................... 1 Present Study .................................................................................................................. 1 Dated Igneous Centers and Associated Mineral Deposits.............................................. 2 Ute Mountains..............................................................------......-......-....."-----......--... 6 La Plata Mountains................................................................................................. 8 Rico......................................................................................................................... 9 Chicago Basin Stock............................................................................................... 9 Ouray....................................................................................................................... 9 Porphyry Creek and Tomichi Creek Stocks............................................................ 16 Tincup Stock........................................................................................................... 16 Round Mountain Stock........................................................................................... 17 Italian Mountain Intrusive Complex....................................................................... 17 Mount Sopris Stock................................................................................................. 17 Leadville .....................................................'............................................................ 17 West Tennessee Creek Stock................................................................................... 18 West Cross Creek Stock:......................................................................................... 18 East Lake Creek Stock...,....:................................................................................... 18 Fulford Stock.......................................................................................................... 18 Montezuma Stock................................................................................................... 18 Empire Stock........................................................................................................... 19 Apex Stock.!............................................................................................................ 19 Eldora Stock............................................................................................................ 19 Jamestown Stocks................................................................................................... 20 Discussion of the Ages of Intrusive Activity.................................................................. 20 Laramide Igneous Centers ...................................................................................... 20 Middle Tertiary Igneous Centers............................................................................. 21 Late Tertiary Igneous Centers................................................................................. 21 Discussion of the Ages of Mineralization....................................................................... 21 Laramide Ore Deposits........................................................................................... 22 Middle Tertiary Ore Deposits ................................................................................. 23 Late Tertiary Ore Deposits...................................................................................... 23 Conclusions..................................................................................................................... 24 Acknowledgments........................................................................................................... 25 References Cited............................................................................................................. 26 FIGURES 1. Index map of the Colorado Mineral Belt, showing its relationship to the San Juan volcanic field, Rio Grande rift, and -300-milligal Bouguer gravity anornaly .................................................................................................................. 2 2. Late Cretaceous and early Tertiary (Laramide) intrusions, Colorado............................................................................. 10 3. Middle Tertiary intrusions, Colorado.............................................................................................................................. 12 4. Late Tertiary intrusions, Colorado................................................................................................................................... 14 TABLES 1. Fission-track and K-Ar analytical data............................................................................................................................ 3 2.
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