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Geology and Mineralogy Thi§ Document Consists of 158 Pages Series A CxoeO Geology and Mineralogy Thi§ document consists of 158 pages Series A UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY STRATIGRAPHY OF TRIASSIC AND ASSOCIATED FORMATIONS IN PART OF THE COLORADO PLATEAU REGION* John H. Stewart, George A. Williams, Howard F. Albee, and Omer B. Raup; with a section on SEDIMENTARY PETROLOGY by Robert A. Cadigan June 1956 Trace Elements Investigations Report 397 This preliminary report is distributed without editorial and technical review for conformity with official standards and nomenclature. It is not for public inspection or quotation. #This report concerns work done on behalf of the Division of Raw Materials of the U. S. Atomic Energy Commission. USGS - TEI-397 GEOLOGY AND MINERALOGY Distribution (Series A) No. of copies Atomic Energy Commission, Washington. ........... 2 Division of Raw Materials, Albuquerque. .......... 1 Division of Raw Materials, Austin ............. 1 Division of Raw Materials, Gasper ............. 1 Division of Raw Materials, Denver ............. 1 Division of Raw Materials, Ishpeming. ........... 1 Division of Raw Materials, Phoenix, ............ 1 Division of Raw Materials, Rapid City ........... 1 Division of Raw Materials, Salt Lake City ......... 1 Division of Raw Materials, Spokane. ............ 1 Division of Raw Materials, Washington ........... 3 Exploration Division, Grand Junction Operations Office. 6 Grand Junction Operations Office. ............. 1 Technical Information Extension, Oak Ridge. ........ 6 U. S. Geological Survey: Fuels Branch, Washington. ................. 1 Geochemistry and Petrology Branch, Washington ....... 1 Geophysics Branch, Washington ........ , ...... 1 Mineral Deposits Branch, Washington ............ 3 P. G. Bateman, Menlo Park ................. 1 A. L. Brokaw, Grand Junction. ...... t ........ 6 N. M. Denson, Denver. ................... 1 V. A. Fischer, Washington ................. 1 ?. L. Freeman, College. .................. 1 R. L. Griggs, Albuquerque ................. 1 W. R. Keefer, Laramie ................... 1 M. R. Klepper, Spokane. .................. 1 A. H. Koschmann, Denver .................. 1 L. R. Page, Washington, o ................. 1 Q. D. Singewald, Beltsville ................ 1 A. E. Weissenborn, Spokane. ................ 1 TEPCO, Denver ....................... 2 TEPCO, RPS, Washington, (including'master). ........ 4 IT 3 CONTENTS Page Abstract * ......................... o, Introduction ........................ ^4 Scope ......................... ]7 Terminology and methods used in the classification of sedimentary rocks. ................ -^Q Terminology and methods used in sedimentary structure studies . ... o .................. 21 Stratigraphy ........................ 22 Permian rocks .................... 0 22 Triassic rocks. .................... 26 Moenkopi formation ................ 26 General characteristics ........... 26 Interpretation ............... 31 Chinle formation ................. 32 Temple Mountain member. ........... 35 Shinarump member. .............. 39 General characteristics. ........ 39 Pebble studies ............. 43 Sedimentary structure studies. ..... 46 Monitor Butte member* ............ 46 Moss Back member, .............. 51 Pebble studies ............. 55 Sedimentary structure studies. ..... 55 Petrified Forest member ........... 55 Owl Rock member ......... .... 58 Church Rock member* ............% 59 Sedimentary structure studies. ..... 63 Some characteristics of the Chinle formation. 63 Thickness ................ 63 Paleontology .............. 66 Interpretation .............. 66 Triassic and Jurassic rocks .............. 69 Glen Canyon group. ................ 69 Wingate sandstone .............. 69 Kayenta formation .............. 70 Navajo sandstone. .............. 71 Interpretations ............... 71 Relation of uranium deposits to the stratigraphy of the Triassic and associated formations. ....... 72 Distribution of ore deposits ........... 72 Permian rocks ................ 72 Cutler formation ............ 72 Triassic rocks. ............... 73 Moenkopi formation ........... 73 Chinle formation ............ 73 Wingate sandstone. ........... 76 Relation of ore deposits to local sedimentary features. 77 Channel fills. .................. 77 Lithologic features. .............. e 77 Page Sedimentary petrology5 by Robert A. Gadigan ......... 78 Introduction . .................... 78 Objectives ....................... 79 Methods. ........................ 79 Methods of textural analysis. ........... 79 Methods of compositional analysis ..... e ... 85 Results. ....... ...............* 90 Permian rocks ...... t ............ 92 Cutler formation ............... 92 Cedar Mesa sandstone member ....... 92 Organ Rock member ............ 94 DeChellysandstone member. ........ 96 Hoskinnini tongue ............ 98 Conglomeratic facies of the Cutler formation ............... 100 Triassic rocks .................. 100 Moenkopi formation . ............ 100 Chinle formation ............... 102 Shinarump member. ....<>..... 102 Monitor Butte member. .......... 106 Moss Back member. ............ 109 Petrified Forest member ......... 112 Owl Rock member ............. 114 Church Rock member. ........... 116 Triassic and Jurassic rocks . ... a ....... 118 Glen Canyon group. .............. 118 Win^gate sandstone. ........... 118 Kayenta formation ............. 121 Navajo sandstone. ............ 122 Study of the clay mineral groups in the Triassic and associated formations. t .............. 123 Petrologic features observed in ore-bearing sandstones . 127 Interpretations. .................... 130 Summary of stratigraphic and petrologic interpretations. 140 Selected bibliography .................... 145 Unpublished reports ..................... 149 5 APPENDICES Page Appendix I. Mean or average measures of .the properties of the phi distribution of the grain size of some Permian, Traissic, and Jurassic sand"- stones and coarse siltstones from the Colo­ rado Plateau. (Size properties are given in millimeters. Deviation properties are given in phi units, which correspond to Wentworth size grades.) ............. f .. 150 II. Percent mineral composition of samples of the Shinarump member of the Chinle formation as determined by point-count analyses of thin sections. ........... T ...... 153 III. Percent mineral composition of samples of the Monitor Butte member of the Chinee formation as determined by point-count analyses of thin sections* es«.t.«. it*. *....* 155 IV. Percent mineral composition of samples of the Moss Back member of the Chinle formation as determined by point-count analyses of thin sections. .................. 157 V. Percent mineral composition of samples of the Petrified Forest member of the Chinle for­ mation as determined by point-count analyses of thin sections. .............. 158 6 ILLUSTRATIONS Page Figure 1. Index map of part of the Colorado Plateau showing areas of stratigraphic studies .......... 15 2. Generalized section of Triassic rocks and part of the Permian and Jurassic rocks in southeastern Utah and adjoining areas ............. 16 3. Isopachous map of the Moenkopi formation in south­ eastern Utah ................... 2? 4. Index map of part of Colorado Plateau showing outcrops of the Chinle formation ......... 34 5. Correlations of the Chinle formation .,.....» 36 6. Distribution of the Shinarump member of the Chinle formation and location of uranium deposits in this member in southeastern Utah and northeastern Arizona. ..................... 42 7. Map of resultant dip directions of cross-strata in the Shinarump member of the Chinle formation. 47 8. Distribution of the Monitor Butte member of the Chinle formation and location of the uranium deposits in this member in southeastern Utah . 48 9. Distribution of the Moss Back member of the Chinle formation; location of uranium deposits in the Moss Back and at the base of undifferentiated Chinle; and a generalized isopachous map of that part of the Chinle formation underlying the Moss Back member. ................... 52 7 Page Figure 10. Map of resultant dip directions of cross-strata in the Moss Back member of the Chinle formation. 4 56 11. Map of resultant dip directions of cross-strata 0 in various sandstone units in the Chinle formation^ ................... 64 12. Isopachous map of the Ghinle formation in south­ eastern Utah .................. 65 13. Generalized cross section showing distribution of ore deposits in the Chinle formation. * . 75 14. Illustration of the petrologic classification of detrital sedimentary rocks (After Pettityohn, * « 1949> and Krynine, oral communication, 1952) . 89 15. Index map of parts of Arizona and Utah showing sedimentary petrology sample localities... ... 93 16. Changes in average grain size and average sorting from Upper Permian to Lower Jurassic units in the central part of the Colorado Plateau .... 135 8 TABLES Page Table 1* Size classification (after Wentworth 1922) ........ 19 2. Field classification of detrital sedimentary rocks .... 20 3. Average percent composition of pebbles in the Shinarump member of the Ghinle formation of . southern Utah. .^. ............... 44 4. percent of quartzose pebble types in the Moss Back member of the Chinle formation in part of southeastern Utah. ................... 55 5. Phi mean and Wentworth grain-size classification ...... 81 6. Classification of sorting. ................ 83 7. Classification of skewness ................ 84 8. Classification of kurtosis or peakedness ......... 84 9. The petrologic classification of detrital sedimentary rocks.
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