Brigham Young University BYU ScholarsArchive Theses and Dissertations 2011-11-10 Sequence Stratigraphy of Basal Oquirrh Group Caronates (Bashkirian) Thorpe Hills, Lake Mountain, Wasatch Front, Utah Andrew D. Derenthal Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Geology Commons BYU ScholarsArchive Citation Derenthal, Andrew D., "Sequence Stratigraphy of Basal Oquirrh Group Caronates (Bashkirian) Thorpe Hills, Lake Mountain, Wasatch Front, Utah" (2011). Theses and Dissertations. 2705. https://scholarsarchive.byu.edu/etd/2705 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Sequence Stratigraphy of the Basal Oquirrh Group (Bashkirian) Carbonates, Thorpe Hills, Lake Mountain, Wasatch Front, Utah Andrew D. Derenthal A thesis submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Master of Science Scott M. Ritter, Advisor Thomas H. Morris Brooks B. Britt Department of Geological Sciences Brigham Young University December 2011 Copyright © 2011 Andrew D. Derenthal All Rights Reserved i ABSTRACT Sequence Stratigraphy of the Basal Oquirrh Group (Bashkirian) Carbonates, Thorpe Hills, Lake Mountain, Wasatch Front, Utah Andrew D. Derenthal Department of Geological Sciences Master of Science The Early Pennsylvanian (Bashkirian/Morrowan) Bridal Veil Limestone of north- central Utah was deposited in the eastern portion of the rapidly subsiding Oquirrh basin. The 420 meter-thick Bridal Veil Limestone displays distinct cyclicity formed by stacked, meter to decameter scale high-frequency sequences and their constituent parasequences. Though no one ideal cycle may be defined for the Bridal Veil Limestone, each high- frequency sequence and parasequence contains a general shallowing upward trend that ranges from anaerobic to dysaerobic mudstone at the base to skeletal wackestone to mud- dominated packstone, capped by heterozoan grain-rich carbonates or siliciclastic tidalites. Cycles bounded by exposure surfaces, indicated by micro-brecciation, rhizoliths, laminated calcite or silica crusts, rip-up clasts, centimeter-scale teepee structures, and/or pronounced erosional relief are termed high-frequency sequences. Those bounded by marine flooding surfaces are defined as parasequences. Thusly defined, the Bridal Veil Limestone is divided into 25 high-frequency sequences designated BVL-1 through BVL- 25. Overall, two distinct sets of high-frequency sequences may be observed in the Bridal Veil Limestone. Sequences comprising the lower half of the formation (BVL-1 through BVL-12) are thicker, muddier, and less sand-prone than sequences in the upper half of the formation (BVL-13 through BVL-25), indicating an overall change in oxygenation, depositional texture, and accommodation upward in the section. Tracing of key beds and surfaces between the Thorpe Hills, Lake Mountain, and the Wasatch Range (spanning a distance greater than 50 miles) reveals that deposition was remarkably uniform across the southeastern part of the Oquirrh basin which we herein designate the Bridal Veil sub-basin and distinct from coeval formations in the southern Oquirrh basin, Ely basin, and Wyoming shelf. Mudstone and wackestone textures comprise a large portion of the formation by volume. Grain-rich carbonates are almost exclusively heterozoan in composition, indicating that the sub-basin was subphotic to aphotic through Early Pennsylvanian time. ii Acknowledgements I am deeply indebted to all those who assisted in the completion of this project. I owe special thanks to Dr. Scott Ritter, who not only offered help and expertise, but also, friendship and counsel throughout my undergraduate and graduate endeavors at Brigham Young University. I doubt I will meet another person who is so generous in giving of his time and talents and who displays such a love for teaching and learning. I would also like to thank Dr. Tom Morris, Dr. Brooks Britt, and Dr. Eric Christiansen for their input to the study. Of my fellow students and friends, I thank Chris Spencer, Kevin McGuire, Corey Dong, Sean Derenthal, and Christian Derenthal for assistance in field work. The research for this project was made possible by generous funding from Dr. Scott Ritter. Thank you to my wife, Tracy, an elect woman, for her patience and strength, and to my family. iii Table of Contents INTRODUCTION .............................................................................................................. 1 BACKGROUND AND GEOLOGIC SETTING................................................................ 2 METHODS ......................................................................................................................... 3 MICROFACIES DESCRIPTIONS .................................................................................... 4 MF 1: Anaerobic Mudstone ............................................................................................ 4 Description .................................................................................................................. 4 Interpretation .............................................................................................................. 5 Occurrence .................................................................................................................. 5 MF 2: Dysaerobic Spiculite Mudstone ........................................................................... 5 Description .................................................................................................................. 5 Interpretation .............................................................................................................. 6 Occurrence .................................................................................................................. 6 MF 3: Dysaerobic Sparse Skeletal Wackestone ............................................................. 7 Description .................................................................................................................. 7 Interpretation .............................................................................................................. 7 Occurrence .................................................................................................................. 7 MF 4: Aerobic Mudstone to Sparse Skeletal Wackestone .............................................. 8 Description .................................................................................................................. 8 Interpretation .............................................................................................................. 8 Occurrence .................................................................................................................. 9 MF 5: Skeletal Wackestone ............................................................................................ 9 Description .................................................................................................................. 9 Interpretation .............................................................................................................. 9 Occurrence .................................................................................................................. 9 MF 6: Mud-dominated Skeletal Packstone ................................................................... 10 Description ................................................................................................................ 10 Interpretation ............................................................................................................ 10 Occurrence ................................................................................................................ 11 MF 7: Wackestone Caprock .......................................................................................... 11 Description ................................................................................................................ 11 Interpretation ............................................................................................................ 11 iv Occurrence ................................................................................................................ 11 MF 8: Skeletal Packstone Caprock ............................................................................... 12 Description ................................................................................................................ 12 Interpretation ............................................................................................................ 12 Occurrence ................................................................................................................ 13 MF 9: Mixed Grain Packstone to Grainstone Caprock ................................................. 13 Description ................................................................................................................ 13 Interpretation ............................................................................................................ 13 Occurrence ................................................................................................................ 14 MF 10: Mixed Siliciclastic/Carbonate