CLASTIC LARAMIDE SEDIMENTS OF THE WASATCH HINTERLAND, NORTHEASTERN UTAH by Daven Craig Mann A thesis submitted to the faculty of the University of Utah in partial fulfillment of the requirement for the degree of o • • Master of Science in Geology Department of Geology and Geophysics University of Utah Summer 1974 UNIVERSITY OF UTAH GRADUATE SCHOOL SUPERVISORY COMMITTEE APPROVAL of a thesis submitted by Daven Craig Mann I have read this thesis and have found it to be of satisfactory quality for a master's degree. * /• % Li, /Eugene Call4.ghan [ChairmartySupervisory Committee T have read this thesis and have found it to be of satisfactory quality for a master's j degree. Date rancis W. Christiansen Member, Svipervisory Committee T have read this thesis and have found it to be of satisfactory quality for a master's decree. Jonathan H. Goodwin [ember, Supervisory Committee UNIVERSITY OF UTAH LIBRARIES UNIVERSITY OF UTAH GRADUATE SCHOOL. FINAL READING APPROVAL To the Graduate Council of the University of Utah: I have read the thesis of Daven Craig Mann in its final form and have found that (1) its format, citations, and bibliographic style are consistent and acceptable; (2) its illustrative materials including figures, tables, and charts are in place; and (3) the final manuscript is satisfactory to the Supervisory Committee and is ready - for submission to the Graduate School. Approved for the Major Department Chairman/Dean Approved for the Graduate Counci Sterling M. McMurrin Dean of the Graduate School ACKNOWLEDGMENT Acknowledgment is made to the Utah Geological and Mineral Survey which financially aided the author while doing the field work. The survey staff contributed many hours in discussing, proof­ reading and typing the manuscript. Amoco Production Company graceously undertook to secure the three K/Ar radiometric dates which were essential to the study. Numerous people aided and encouraged the field work and preparation of the manuscript. Dr- Eugene Callaghan spent untold hours both in the field and in reviewing the paper, his eye for geology is responsible for much of the stratigraphy contained here. The other members of the graduate committee Dr- Jonathan H. Goodwin and Dr. Francis W. Christiansen gave very helpful instructions regarding the manuscript. Gratitude is also extended to the following people who helped in many ways: Howard R. Ritzma, Dr. William L. Stokes, Dr. William P. Hewitt, Sylvia N. Goeltz, M. D. Crittenden Jr. , Clara Warr and the many authors who treated the subject before me. My wife, Kathryn, also deserves credit for her support and encouragment while taking upon herself extra burdens in order to allow me more time for this project. TABLE OF CONTENTS ABSTRACT . • • ix INTRODUCTION . 1 PREVIOUS INVESTIGATIONS 4 STRATIGRAPHY AND LITHOLOGY 9 Echo Canyon Conglomerate • • 12 History and Age . 12 Lithology 12 Location and Stratigraphy • • • 13 Evanston Formation 15 History and Age • . 15 Lithology 15 Location and Stratigraphy 19 City Creek Canyon Volcanics . 22 History and Age • • 22 Lithology 23 Location and Stratigraphy . • 25 Wasatch Formation 27 History and Age » • • 27 Lithology . * 29 Western Conglomerate Facies 29 Eastern Sandstone-Mudstone Facies . 42 Fowkes Formation 47 Norwood Tuff 49 Perrys Hollow Fanglomerate 52 CORRELATION 56 Echo Canyon Conglomerate - Price River and Bennion Creek Formations .56 Currant Creek Formation and North Horn Formations - Evanston Formation . » • • 59 Colton Formation - Wasatch Formation • • 60 PALEOCURRENT STUDY 62 General Statement • 62 Procedure 63 Results • 64 Echo Canyon Conglomerate 64 TABLE OF CONTENTS CONTINUED Evanston Formation 66 Wasatch Formation 68 PEBBLE COUNT 73 STRUCTURAL HISTORY 77 General Statement 77 Phases of the Laramide Orogeny ................ 81 Early Laramide Orogeny - Late Cretaceous. 81 Late Phase of the Early Laramide Orogeny- Late Cretaceous • 83 Mid Laramide Orogeny - Late Paleocene to Early Eocene 85 Late Laramide Orogeny - Late Eocene to Early Oligocene 86 ECONOMIC AND ENGINEERING GEOLOGY 90 Landsliding 91 CONCLUSIONS . 93 BIBLIOGRAPHY 96 APPENDIX 102 Measured Section 103 VITA 113 ILLUSTRATIONS FIGURE PAGE 1. History of the stratigraphic nomenclature ... 5 2. Estimated basins of deposition in the Wasatch Hinterland 10 3. Idealized cross-section of the Wasatch Hinterland 11 4. Iron nodule from the Evanston Formation ... 17 5. Unconformity between the Wasatch and Evanston Formations 21 6« City Creek Canyon volcanics 24 7. Columnar section of the western conglomer­ ate facies of the Wasatch Formation 31 8. Large boulder in the Wasatch Formation . 32 9» Framework type conglomerate from the Wasatch Formation 34 10. Photomicrograph of the Wasatch Formation . 3 5 11. Siltstone and sandstone beds within the western conglomerate facies 36 12. Festoon cross-stratification in the Wasatch Formation 37 13. Large oncolites in limestone from the western conglomerate facies 39 14. Concentric banding in an oncolite 40 15. Photomicrograph of a probable shell frag­ ment forming the nucleus of an oncolite .... 41 16. Photomicrograph of a gastropod forming nucleus of an oncolite 42 17. Possible root fragments from the Wasatch Formation 43 18. Photomicrograph of possible Goniobasis (? ) from the western conglomerate facies .... 43 19« Fossiliferous limestone cobble of the Park City Formation 44 20. Inner cast of a turtle shell 46 21. Tertiary volcanics of the Wasatch Hinter­ land 48 22. Outcrop of the Norwood Tuff near East Canyon Reservoir 51 23. Preliminary map of the Perrys Hollow fanglomerate 53 24. Perrys Hollow fanglomerate at the mouth of Perrys Hollow • • • 54 ILLUSTRATIONS — CONTINUED FIGURE PAGE 25. Photomicrograph of the Perrys Hollow fanglomerate 54 26A. Correlation chart for the Wasatch Hinterland and western Uinta Basin 57 26B. Correlation chart for the Wasatch Hinterland and western Uinta Basin 58 27. Compass diagram for the Echo Canyon Conglomerate 65 28. Compass diagram for the Evanston Formation 67 29* Compass diagram for the Wasatch Formation 70 30. Paleocurrent vector map of the Wasatch Formation 71 31. Compass diagram for the Wasatch Formation on the Salt Lake City Salient . 72 32. Orogenic belts in Utah and Nevada 78 33. Unconformity between the underlying Echo Canyon Conglomerate and the Evanston Formation in lower Echo Canyon • 84 34. Unconformity between the Wanship Form­ ation and the Wasatch Formation 87 35. Unconformity between the folded Paleozoic beds and the Wasatch Formation 87 36. Unconformity between the Evanston Form­ ation and the Wasatch Formation 88 37. Landslide in the elastics in Echo Canyon . 92 TABLE 1. Pebble count in the conglomerates of the Wasatch Hinterland 7 5 2. Orogenic phases and results in the Wasatch Hinterland 80 3. Radiometric dates for the Late Laramide igneous deposits in the Wasatch Hinterland and adjoining areas 82 PLATE 1. Generalized geologic map of the Laramide Orogenic sediments of the Wasatch Hinterland in pocket ABSTRACT Four phases of the Laramide Orogeny are mirrored in the molasse-type sediments of the Wasatch Hinterland (Eardley, 1952, p. 52). The present nomenclature for these sediments is, from oldest to youngest: the Echo Canyon Conglomerate, Evanston Form­ ation, and Wasatch Formation. Several tools useful in separating these formations are: (1) lithologic characteristics, (2) pebble counts, (3) paleocurrent studies, (4) radiometric dating of volcanic rocks, (5) facies relationships, (6) sedimentary expressions of Laramide tectonic phases, (7) subsidence basins, and (8) correla­ tion of the sediments with similar units outside the Wasatch Hinter­ land. The Echo Canyon Conglomerate was deposited from west to east in the center of the Hinterland. The Evanston Formation con­ sists of a lower conglomerate and an upper sandstone-siltstone unit. In the Salt Lake City Salient, the City Creek Canyon volcan­ ics (tentative name) which overlie the Evanston Formation were found to be early Eocene (50 and 55 m. y. ) by radiometric dating. This date gives a maximum age for the portion of the Wasatch Formation represented in the Salient where it unconformably overlie the volcanics. The early Eocene Wasatch Formation was deposi- ted from west to east during a later phase of the Laramide Oroge but because of its large lateral extent it is divided into two facies a western conglomerate facies and an eastern sandstone-mudston facies. x INTRODUCTION A broad belt of coarse, clastic sediments occurs along the border between the Great Basin, the Rocky Mountains and the Colorado Plateaus. The sediments are similar in many respects to classic molasse deposits of the forelands of the European Alps. These molasse-type sediments form a long, narrow band of outcrops that extend almost the entire length of Utah and well into Idaho. A review by Rutten ( 1962, p. 602-603) explained that the classical molasse sediments were deposited in subsiding basins adjacent to abruptly uplifted mountain fronts. As early as 1928, Cadisch recorded orogenic phases and variations of the rising Alps by the study of the molasse and flysch sediments in the fore­ lands. During the Late Cretaceous and Early Tertiary, erosion of areas uplifted as a consequence of the Laramide Orogeny in the western United States blanketed the Wasatch Hinterland with thick sequences of molasse-type conglomerates. Hintze (1973, p. 76) commented that: One of the greatest difficulties in all of this work is in identifying the ages of various conglomerates. develop­ ment of some uncontestable means of showing the true ages of the conglomerates might modify