Brigham Young University BYU ScholarsArchive Theses and Dissertations 2008-11-11 Investigating the margins of Pleistocene lake deposits with high- resolution seismic reflection in Pilot alleV y, Utah John V. South Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Geology Commons BYU ScholarsArchive Citation South, John V., "Investigating the margins of Pleistocene lake deposits with high-resolution seismic reflection in Pilot alleV y, Utah" (2008). Theses and Dissertations. 1641. https://scholarsarchive.byu.edu/etd/1641 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]. INVESTIGATING THE MARGINS OF PLEISTOCENE LAKE DEPOSITS WITH HIGH-RESOLUTION SEISMIC REFLECTION IN PILOT VALLEY, UTAH by John V. South A thesis submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Master of Science Department of Geological Sciences Brigham Young University December 2008 BRIGHAM YOUNG UNIVERSITY GRADUATE COMMITTEE APPROVAL of a thesis submitted by John V. South This thesis has been read by each member of the following graduate committee and by majority vote has been found to be satisfactory. Date John H. McBride, Chair Date Stephen T. Nelson Member Date Alan L. Mayo Member BRIGHAM YOUNG UNIVERSITY As chair of the candidate’s graduate committee, I have read the thesis of John V. South in its final form and have found that (1) its format, citations, and bibliographical style are consistent and acceptable and fulfill university and department style requirements; (2) its illustrative materials including figures, tables, and charts are in place; and (3) the final manuscript is satisfactory to the graduate committee and is ready for submission to the university library. Date John H. McBride Chair, Graduate Committee Accepted for the Department Michael J. Dorais Graduate Coordinator Accepted for the College Thomas W. Sederberg Associate Dean, College of Physical and Mathematical Sciences ABSTRACT INVESTIGATING THE MARGINS OF PLEISTOCENE LAKE DEPOSITS WITH HIGH-RESOLUTION SEISMIC REFLECTION IN PILOT VALLEY, UTAH John V. South Department of Geological Sciences Master of Science A vast area of the northeastern Great Basin of the western USA was inundated by a succession of Plio-Pleistocene lakes, including Lake Bonneville (28 ka to 12 ka). The Pilot Valley playa, located just east of the Utah-Nevada border near Wendover, Utah, within the eastern Basin and Range Province, represents an 8 to 16 km wide and ~50 km long remnant of these lakes. The playa corresponds to the upper surface of a closed basin that is delimited by two mountain ranges, which are mantled by recent alluvial fans over which the playa sediments have prograded. In order to investigate the interaction of Plio- Pleistocene lake sedimentation and alluvial fan development, high-resolution seismic reflection profiles have been acquired near the base of both the west-bounding and the east-bounding ranges. On the western side of the basin, the seismic profiles provide images of sub-horizontal playa sediments prograding over the inclined alluvial fans. The boundary between the playa and fan sediments is marked by a prominent angular unconformity. Seismic images from the eastern side of the basin reveal a markedly different structural and stratigraphic style with down-to-the-basin normal faulting of relatively shallow Paleozoic bedrock overlain by alluvial fan deposits, which are in turn on-lapped by a thin veneer of playa sediments. The results contained herein reveal for the first time the stratigraphic relationships between Quaternary pluvial sediments as a shoreline depositional facies and the adjacent bounding fan deposits. Post-stack reprocessing of lower-resolution but deeper penetration seismic data located in an analogous basin to the southwest, provides a likely context for the Pilot Valley seismic data. The new geophysical images, when integrated with available geologic mapping and limited well control, aid in constraining how deep aquifers are locally recharged from an adjacent range. The results also clearly demonstrate the strong structural asymmetry of the range and playa system, which is consistent with a classic half-graben structure. Lastly, this study demonstrates the utility of the shallow seismic reflection method as a tool to provide high-resolution sub-surface images in the geophysically challenging environment of Basin and Range geology. ACKNOWLEDGMENTS I wish to thank the many people who helped acquire the data. Specific gratitude is extended to Stephanie Ashley, Greg Carling, Nicole Cox, Eleanor McBride, Allan South, Maxwell Okure, Mary South, and Michelle Bushman. Thanks to many people who added their counsel or advice, especially my thesis committee of John McBride, Steve Nelson, and Alan Mayo, and including Brady Tingey, Jeremy Gillespie, Greg Carling, Ron Harris, Chris Potter, Dave Tingey, William Hokanson, Wes Lifferth, and Riley Brinkerhoff. Acquisition of the seismic profile FC-03 was performed by the 2003 BYU Field Camp Students and co-supervised by Christopher E. Bexfield. I am grateful for correspondence and insights from David Miller. I express my gratitude for the owners and operators of the TL Bar Ranch for willingly offering the use of their property for conducting much of my field work. Thanks also to Spencer for helping me in the lab and to friends and family who helped by tending him. I especially wish to thank my patient wife who helped me immensely. This research was made possible through grants from the Geological Society of America, Seismic Micro-Technology, Inc. and Landmark Graphics Corporation (Halliburton). Thanks to the Department of Geological Sciences – including all the faculty and staff, the College of Physical and Mathematical Sciences, and Brigham Young University. I am very grateful I have had this opportunity to better myself, especially within such a nurturing environment. TABLE OF CONTENTS INTRODUCTION............................................................................................................. 1 REGIONAL SETTING.................................................................................................... 3 Surface Geology of Seismic Profiles ............................................................................. 5 Ground Water................................................................................................................. 7 METHODS ........................................................................................................................ 8 Seismic Data Acquisition............................................................................................... 8 Processing..................................................................................................................... 11 RESULTS ........................................................................................................................ 13 Lines FC-03 and 2........................................................................................................ 13 Line 1............................................................................................................................ 15 Line 3............................................................................................................................ 16 DISCUSSION .................................................................................................................. 19 CONCLUSION ............................................................................................................... 22 REFERENCES................................................................................................................ 26 FIGURES......................................................................................................................... 30 vii LIST OF FIGURES Figure 1 - Reference map of Pilot Valley ......................................................................... 31 Figure 2 - Simplified geology of Pilot Valley .................................................................. 32 Figure 3 - Cross section of TDS levels at the playa margin ............................................. 33 Figure 4 - Map of the Bonneville Basin............................................................................ 34 Figure 5 - Geology of Line 3, NW Silver Island .............................................................. 35 Figure 6 - Locations of springs in Pilot Valley................................................................. 36 Figure 7 - Map view of the west side of the valley from aerial photo.............................. 37 Figure 8 - Photo taken from the top of Pilot Peak ............................................................ 38 Figure 9A - Shot record from Line 2 (SIN 45) ................................................................. 39 Figure 9B - Shot record from Line 2 (SIN 412-413)........................................................ 40 Figure 10 - Stacked seismic section of Line 1. ................................................................. 41 Figure 11 - Stacked time section of Line FC-03............................................................... 42 Figure 12 - Line 2 seismic cross-section..........................................................................