Geology, Altered Rocks And Ore Deposits of The San Rafael Swell Emery County, Utah
By C. C. HAWLEY, R. C. ROBECK, and H. B. DYER
GEOLOGICAL SURVEY BULLETIN 1239
A study of the stratigraphy, structure, alteration, and uraniferous deposits in sedimentary rocks, with emphasis on the Chinle Formation Prepared on behalf of the U.S. Atomic Energy Commission
UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1968 UNITED STATES DEPARTMENT OF THE INTERIOR
STEWART L. UDALL, Secretary
GEOLOGICAL SURVEY
William T. Pecora, Director
Library of Congress catalog-card No. GS 67-287
For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS
Abstract... ______1 Introduction_____._.______-______--_-_-______--_--_ 5 Location and geography______7 Some previous geologic investigations-______!.-- ___ - 7 Sources of data and acknowledgments _-_---_--______9 Stratigraphy______.____.______-_---- 10 Pre-Triassic rocks______10 Triassic System.______11 Moenkopi Formation______-_-___-______-_---_ 11 Chinle Formation______14 Monitor Butte and Temple Mountain Members______14 Moss Back Member_____.______20 Channels in the Chinle Formation______23 Church Rock Member______-___-__-______------25 Triassic and Jurassic Glen Canyon Group______-__-___-_---__ 26 Post-Glen Canyon rocks______-______-______-____-_---- 27 Igneous rocks.______27 Warm springs..______28 Structure______28 Folds______29 Collapse structures.______31 Temple Mountain area______--__- 31 Reds Canyon and vicinity______.___.___-- 32 North part of the swell______34 Origin______34 Bedding-plane fractures-______--- 34 High-angle faults______35 Age and origin of structures______-_------37 Altered rocks______39 Altered rocks in the Moenkopi Formation______-- 40 Altered rocks in the lower part of the Chinle Formation.______. 42 Description and occurrence______--__-______-_------42 Mineralogy ______44 Chemical nature of the alteration...______45 Altered Monitor Butte Member in the Delta mine area_ 46 Altered Monitor Butte or Temple Mountain Members in other areas______50 Bleached rocks at the base of the Moss Back Member of the Chinle Formation and other sandstone-rich units ______- 53 Origin of the purple-white and bleached rocks of the Chinle Formation-,______55 Altered rocks hi the Glen Canyon Group.______- 57
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