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The Geology of the Southern Bull Mountain Area, Jefferson County, Montana

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The Geology of the Southern Bull Mountain Area, Jefferson County, Montana Western Michigan University ScholarWorks at WMU Master's Theses Graduate College 12-1983 The Geology of the Southern Bull Mountain Area, Jefferson County, Montana Michael Edward Streeter Follow this and additional works at: https://scholarworks.wmich.edu/masters_theses Part of the Geology Commons Recommended Citation Streeter, Michael Edward, "The Geology of the Southern Bull Mountain Area, Jefferson County, Montana" (1983). Master's Theses. 1653. https://scholarworks.wmich.edu/masters_theses/1653 This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. THE GEOLOGY OF THE SOUTHERN BULL MOUNTAIN AREA, JEFFERSON COUNTY, MONTANA by Michael Edward Streeter A Thesis Submitted to the Faculty of The Graduate College in partial fulfillm ent of the requirements for the Degree o f Master o f Science Department o f Geology Western Michigan University Kalamazoo, Michigan December 1983 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. THE GEOLOGY OF THE SOUTHERN BULL MOUNTAIN AREA, JEFFERSON COUNTY, MONTANA Michael Edward S tre e te r, M.S. Western Michigan University, 1983 The Late Cretaceous-Early Tertiary Laramide orogeny was responsible for the northward tiltin g of the pre-Eocene rocks of the area. The Late Cretaceous deposition of the Elkhorn Mountains Volcanics resulted in the volcanic-Madison Group unconformity. Late Cretaceous faulting took place probably in response to caldera sub­ sidence. Laramide u p li f t erosion and downstream tra n sp ort resulted in the deposition of the Conrow Creek conglomerate and debris flows over the Lodgepole Limestone. Block faulting took place in response to regional extension probably during Late Oligocene-Early Miocene time resulting in the formation of the St. Paul's Gulch, Golden S u n lig h t, and Boulder basin fa u lts . The Oligocene Dunbar Creek Member (Renova Formation) and the Late Miocene-Pliocene Sixmile Creek Formation were deposited as stream channel and mudflow deposits in the North Boulder River basin. The sandstone units are composed of particles derived from the Boulder batholith and Elkhorn Mountains Volcanics. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGEMENTS I would like to thank the following people who made the completion of this work possible. I have Dr. Christopher J. Schmidt to thank for the idea of this study, his guidance in the field, and his useful criticism as my thesis advisor. Thanks also go to Dr. William B. Harrison III and Dr. W. Thomas Straw for their advice. I would also like to thank the Graduate College for their financial support, William G. Gierke for his companionship and transportation to Montana, and Robert Havira (Western Michigan University) for help in technical areas and with photography. I would especially like to thank Lori G riffin and family for their warm hospitality during my stay in Whitehall, Montana. Heartfelt thanks go to Kim, my wife, for her moral support and love. Michael Edward Streeter i i Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1322432 STREETER, MICHAEL EDWARD THE GEOLOGY OF THE SOUTHERN BULL MOUNTAIN AREA, JEFFERSON COUNTY, MONTANA WESTERN MICHIGAN UNIVERSITY M.S. 1983 University Microfilms internstionsi 300N.ZtebRoad,AnnAibor,MI48106 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. NOTE TO USERS Page(s) not included in the original manuscript are unavailable from the author or university. The manuscript was microfilmed as received. 72-74 This reproduction is the best copy available UMI’ Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ACKNOWLEDGEMENTS ........................................................................................ \ i i LIST OF TABLES................................................................' .............................. v LIST OF FIGURES.................................................................................................vi LIST OF MAPS vi i i INTRODUCTION ....................................................................................................... 1 PREVIOUS WORK................................................................................................... 5 REGIONAL SETTING ............................................................................................... 6 PRECAMBRIAN THROUGH CRETACEOUS STRATIGRAPHY ....................................... 14 Introduction .............................................................................................. 14 "Mississippian" Karst and Solution Breccia Development . 14 Elkhorn Mountains Volcanics-Madison Group Unconformity . 19 Late Cretaceous Igneous Intrusion ....................................................... 21 TERTIARY TO RECENT STRATIGRAPHY - BOZEMAN GROUP ............................ 22 Depositional Sequence and S trati graphic Nomenclature .... 22 Petrographic A nalysis: Dunbar Creek Member, Renova Formation .................................................................................... 23 Petrographic Analysis: Sixm ile Creek Formation ........................... 37 CONROW CREEK CONGLOMERATE ........................................................................ 45 LATE CRETACEOUS TO RECENT GEOLOGIC HISTORY ........................................... 50 STRUCTURE.............................................................................................................53 Introduction ............................................................................................ 53 Major Late Cretaceous-Early Tertiary Faults ................................... 55 Major Cenozoic F aults .................................................................................57 i i i Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Minor F a u lts ................................................................................................. 61 Structural History ................................................................................. 62 SUMMARY OF GEOLOGIC HISTORY ..................................................................... 64 Precambrian ..................................................................................................... 64 C a m b ria n ..........................................................................................................66 Devonian-Pennsylvanian ......................................................................... 66 Permian-Middle Cretaceous ..................................................................... 67 Late Cretaceous-Early Tertiary ......................................................... 67 Eocene-Recent ............................................................................................. 68 APPENDIX: MEASURED SECTIONS ..................................................................... 70 BIBLIOGRAPHY............................................. : ........................................................82 iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF TABLES TABLE 1. Modal Analysis o f Sandstone U nit from the Dunbar Creek Member, Renova Formation, Montana ................................. 34 2. Modal Analysis of Sandstone Unit from the Sixm ile Creek Formation ........................................................ 42 3. Modal Analysis o f the Conrow Creek Conglomerate M atrix ........................................................................ 45 v Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES FIGURE 1. Southwestern Montana showing
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