Geology of Green River Formation and Associated Eocene Rocks in South Western Wyoming and Adjacent Parts of Colorado and Utah by W
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Geology of Green River Formation and associated Eocene rocks in south western Wyoming and adjacent parts of Colorado and Utah By W. H. BRADLEY THE GREEN RIVER AND ASSOCIATED TERTIARY FORMATIONS GEOLOGICAL SURVEY PROFESSIONAL PAPER 496-A UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1964 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director The U.S. Geological Survey Library has cataloged this publication as follows: Bradley, Wilmot Hyde, 1899- Geology of Green River Formation and associated Eocene rocks in southwestern Wyoming and adjacent parts of Colo rado and Utah. Washington, U.S. Govt. Print. Off., 1964. iv, 86 p. illus., maps (3 fold. col. in pocket) diagrs., tables. 30 em. (U.S. Geological Survey. Professional Paper 496-A.) Bibliography: p. 81-84. 1. Geology-Wyoming-Green River Formation. 2. Geology, Strati- graphic-Eocene. (Series) For sale by the Superintendent of Docu.ments, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Page A1 Stratigraphy-Continued IntroductionAbstract-------~----------------------------------- ______________________________________ _ 2 Wasatch Formation-Continued Orientation and purpose ________________________ _ 2 Stratigraphic units-Continued Location and extent of the area __________________ _ 3 Cathedral Bluffs Tongue ________________ _ A26 Earlier geologic surveys _________________________ _ 4 New Fork Tongue~--------------------- 27 Field work ____________ :.. ________________________ _ 5 Green River Formation ______________________ -- __ 28 Acknowledgments ______________________________ _ 5 Definition and age _______ ----------------_-- 28 Topography and drainage ___________________________ _ 6 Stratigraphic units ____________________ --- __ _ 28 Luman Tongue ________________________ _ Geologic structure _______ ~ _________________________ _ 9 28 Major structural units __________________________ _ 9 Tipton Tongue and Tipton Shale Member_ 31 Fontenelle Tongue _____________________ _ Faults----------------------------------------- 10 34 Wind River thrust fault ____________________ _ 11 Wilkins Peak Member __________________ _ 35 Uinta fault and Uinta flexure ________________ _ 11 Laney Shale Member __________ -- __ ---_-- 43 Henrys Fork fault _________________________ _ 12 Battle Spring Formation ________________________ _ 48 Continental fault __________________________ _ 13 Bridger Formation _______________ --------------- 48 Faulted zone south of Washakie Basin ________ _ 13 Definition and age ______ ----_------------ __ _ 48 Miscellaneous faults ________________________ _ 14 Clastic sediment _______________________ _ 49 Interpretation of the structure ___________________ _ 14 Pyroclastic sediment_------------------- 49 Pre-Tertiary deformation ___________________ _ 14 Stratigraphic units _________________________ _ 50 Early Eocene deformation __________________ _ 15 White layers ________________ - ______ - _-- 50 Faunal zones __________________________ _ Post-Eocene-pre-Miocene(?) deformation _____ _ 16 54 Post-Miocene deformation __________________ _ 16 Washakie Basin ________________ -- __ ----- _-- 54 Structural effect of original dip and compaction ________ _ 16 Uinta Formation ____________________ ---- ___ --_-- 54 Depositional dip _______________________________ _ 16 Undifferentiated Eocene formations ______________ _ 54 Gravitational compaction _______________________ _ 17 Bishop Conglomerate ________________ -- __ .:.- _-- _-- 55 Regional effect ____________________________ _ 17 Oligocene, Miocene, and Pliocene formations ______ _ 56 Local effects of gravitational compaction ______ _ 17 Undifferentiated Oligocene and Miocene ____ ---- 56 Stratigraphy ______________________________________ _ 18 Browns Park Formation ____________________ - 56 General relations between the Eocene formations __ _ 18 Split Rock Formation __________ -- ___ -------- 57 Lfthologic terms used ___________________________ _ 19 Igneousrocks--------------------------------~ 57 Wasatch For~ation ____________________________ _ 20 Measured sections of the Green River, Wasatch, and ])efinition and age _________________________ _ 20 Bridger Formations ________________________ ---_-- 58 References ________________________________________ _ Stratigraphic units _________________________ _ 20 81 Index ____________________________________________ _ Niland Tongue ________________________ _ 23 83 ILLUSTRATIONS (Plates are in pocket] PLATE 1. Geologic map of part of southwestern Wyoming and adjacent States. 2. Geologic map of the area around Green River, Wyo., showing distribution of the members of the Green River Formation and the underlying Wasatch Formation. 3. Reconnaissance geologic map and structure sections of the Phil Pico Mountain area in northern Utah and extreme southern Wyoming. Page FIGURE 1. Index maP------------------------------------------------------------------------------------------- A3 2. Map showing Great Divide Basin perched on Continental Divide__________________________________________ 8 3. Henrys Fork fault on east flank of Phil Pico Mountain-------------------------------------------------- 12 4. Tertiary-pre-Tertiary relationships at south end of Phil Fico Mountain ___________________'_________________ 13 5. Shore features of Gosiute Lake on island of Jurassic rocks------------------------------------------------- 18 6. Diagram showing the relations of the Green River Formation to the enclosing Wasatch and Bridger Formations_ 18 III IV CONTENTS Page FIGURE 7. Banded gray and red mudstone near the top of the Wasatch Formation __ ---------------------------------- A21 8. White tuff in the Niland Tongue of the Wasatch Formation________________________________________________ 25 9. Typical exposure of the Tipton Shale Member of the Green River Formation________________________________ 34 10. Map showing Gosiute Lake's hydrographic basin and areal extent at several stages___________________________ -36 11. Photograph showing White Mountain and the Wilkins Peak Member of the Green River Formation___________ 37 12. Contact between the Wilkins Peak and Laney Shale Members of the Green River Formation__________________ 38 13. Crystal molds of an unknown salt from the Wilkins Peak Member of the Green River Formation______________ 39 14. Characteristic exposure of the Laney Shale Member of the Green River Formation___________________________ 46 15. Tuffaceous sandstone lens near the base of the Laney Shale Member of the Green River Formation____________ 47 16. Sketch showing extreme differential compaction around thick tuffaceous sandstone lens_______________________ 48 17. Characteristic exposure of the Bridger Formation in Twin Buttes-----------------,------------------------- 49 18. White bench-forming tuff layers in mudstone of the Bridger Formation_____________________________________ 51 19. Map showing outcrops of white layers in the Bridger Formation___________________________________________ 52 20. Petrified log with bark from the Bridger Formation __________________ _,___________________________________ 53 TABLES Page TABLE 1. Pollens, spores, and algae found in the Luman Tongue of the Green River Formation_________________________ A30 2. Chemical analyses of carbonate-rich tuffs from the Tipton Shale Member of the Green River Formation________ 33 3. Boreholes in the Green River Basin drilled to explore for trona or for oil or gas________________________________ 41 4. Chemical analyses of two tuffs from the Wilkins Peak Member of the Green River Formation__________________ 43 5. Chemical analysis of typical dolomitic organic marlstone from the lower part of the Laney Shale Member________ 44 6. Chemical analyses of a rhyolitic and an andesitic tuff from the upper and middle parts 'of the Laney Shale Member_ 47 THE GREEN RIVER AND ASSOCIATED TERTIARY FORMATIONS GEOLOGY OF GREEN RIVER FORMATION AND ASSOCIATED EOCENE ROCKS IN SOUTHWEST ERN WYOMING AND ADJACENT PARTS OF COLORADO AND UTAH By w. H. BRADLEY ABSTRACT Most of the Eocene rocks belong to three formations-Wasatch, Discussed in this report is the geology of the Eocene rocks in an Green River, and Bridger. The Green River Formation is of area of about 17,000 square miles. The purpose of the report lacustrine origin and has the form of a great lens, or pile of lenses, is to provide the geologic foundation necessary to understand within an enormous volume of fluviatile sediments. The fluvia unci reconstruct the conditions under· which the Green River, tile sediments have been divided into the Wasatch and Bridger Wasatch, nncl Bridger Formations came into being and to pro Formations. Though the Bridger Formation is predominantly vide a matrix in which geochemists and mineralogists studying fluviatile, it contains a considerable number of thin extensive parts of the area can set up their models. The report is .based layers of lacustrine sediments. Most of the Wasatch Formation hugely on the author's own fieldwork, which began in the early underlies the Green River Formation, and most of the Bridger 1920's, but it also brings together the findings of many other Formation overlies it; but locally around the margins, the geologists who have worked in the area. Bridger rests directly on the Wasatch. The green River inter Four huge structural units dominate the area. The first two fingers and intertongues with both fluviatile formations. Three nrc the Green River and Washakie Basins, each of which is a tongues of the .Wasatch, as well as the main body