Structural and Lithological Influences on the Tony Grove Alpine Karst
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Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-2016 Structural and Lithological Influences on the onyT Grove Alpine Karst System, Bear River Range, North-Central Utah Kirsten Bahr Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Geology Commons Recommended Citation Bahr, Kirsten, "Structural and Lithological Influences on the onyT Grove Alpine Karst System, Bear River Range, North-Central Utah" (2016). All Graduate Theses and Dissertations. 5015. https://digitalcommons.usu.edu/etd/5015 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. STRUCTURAL AND LITHOLOGICAL INFLUENCES ON THE TONY GROVE ALPINE KARST SYSTEM, BEAR RIVER RANGE, NORTH-CENTRAL UTAH by Kirsten Bahr A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Geology Approved: ______________________________ ______________________________ W. David Liddell, Ph.D. Robert Q. Oaks, Jr, Ph.D. Major Professor Committee Member ______________________________ ______________________________ Thomas E. Lachmar, Ph.D. Mark R. McLellan, Ph.D. Committee Member Vice President for Research and Dean of the School of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2016 ii Copyright © Kirsten Bahr 2016 All Rights Reserved iii ABSTRACT Structural and Lithological Influences on the Tony Grove Alpine Karst System, Bear River Range, North-Central Utah by Kirsten Bahr, Master of Science Utah State University, 2016 Major Professor: Dr. W. David Liddell Department: Geology The fracture-dominated Tony Grove alpine karst system in the Bear River Range in north-central Utah, has caves ranging from 5 m deep, consisting of solution-enlarged single fractures, to the large, 374 m deep, Main Drain Cave, characterized by a series of vertical drops and horizontal passages. The caves in the Tony Grove area are developed throughout the 510 m thick Fish Haven and Laketown Dolomites. The Swan Peak Formation, consisting of orthoquartzite and shale, underlies the dolomites. Surface fracture measurements (n=3502) yielded two distinctive sets of fractures. The northeast-southwest sets had a mean orientation of 41±0.7° and the northwest- southeast set had a mean orientation of 126±0.9°. Subsurface fracture measurements (n=194) yielded a similar northeast-southwest set with a mean of 45±4° and a northwest- southeast set with a mean of 133±5°. Of the sixteen caves surveyed for fractures and iv passages, fifteen were controlled by fractures, although some caves had both fracture- and non-fracture-controlled passages. Only one cave was entirely non-fracture controlled, likely due to a change in lithology. Main Drain Cave, the only cave with long horizontal passages, was surveyed for both fracture and stratigraphic influences on horizontal cave development. Results indicate some sections are controlled by southeast-trending-fractures and other sections are controlled by southwest-dipping-bedding planes. Alternatively, parts of the down-dip- oriented sections may be influenced by southwest-oriented fractures. Stratigraphic control in this cave includes cherty layers that appear to hinder down-cutting of passages into lower stratigraphic units. Surface mapping determined that there is a southeast-oriented fold pair east of the Logan Peak Syncline, consisting of the Naomi Peak Syncline and the Cottonwood Canyon Anticline. The anticline merges with the Logan Peak Syncline near the head of Cottonwood Canyon. The Naomi Peak Syncline continues north-northeast through the Tony Grove area and may divert water from the Tony Grove area to Wood Camp Hollow Spring in Logan Canyon. The anticline acts as a divide between groundwater traveling southwest to Dewitt Spring and south-southeast to Wood Camp Hollow Spring. The Swan Peak Formation appears to act as a barrier to groundwater movement into the underlying formations, separating the Tony Grove system from underlying systems. (242 pages) v PUBLIC ABSTRACT Structural and Lithological Influences on the Tony Grove Alpine Karst System, Bear River Range, North-Central Utah Kirsten Bahr Caves are access points into the subsurface for humans, water, and, in many cases, contaminants. Many caves are connected via a series of conduits that carry water from one cave to another and, eventually, to a spring. However, because most of these conduits are inaccessible, it is difficult to determine the pathway groundwater takes on its way to the spring. The primary objective of this study was to examine the effects of folds, fractures, and rock type upon the formation and orientation of cave passages as well as groundwater flow patterns in the Tony Grove alpine karst system. Although water from this system is not a source for human consumption, studying this relatively easily-accessible system allowed insight into how water travels through alpine karst systems. This may potentially aid in future studies of other similar systems that are used as a source of water for human consumption. The karst system was characterized by geologically mapping the surface and subsurface. Previous studies and non-toxic water-tracing techniques were also used to aid the assessment of how water travels underground from the study area to the spring. The findings indicate that the development of caves in the Tony Grove area is highly influenced by the fractured rock. The folded rock and its geologic orientation, as well as impermeable rock layers, also influence how water travels through this karst system. vi ACKNOWLEDGMENTS I would like to express my sincere gratitude towards all the volunteers that made this project possible. I would especially like thank Gregory (JR) Schenk, W. David Liddell, Nathan Giles, Heather Smith, Jeremiah (JD) Armentrout, David Wrobel, Scott Pratt, Steve Gunderson, John Cox, Colter Davis, Mark Szorik, Lance Dickey, Sean Ingersoll, and Heather Davis for their time in safely collecting cave data in the harsh, cold climate of the Tony Grove caves. I would also like to thank Michael Strange, Matt Rahmeyer, W. David Liddell, Rebekah Wood, Taron Wood, Mark Bahr and Vaughn Bahr for their time spent collecting data on the surface, Lawrence (Larry) Spangler for his knowledge and support in karst hydrology and dye tracing, Peter Hartley for his knowledge of Main Drain Cave and the Tony Grove area, and Eric Sodja for his assistance with ArcGIS. I want to thank David Schurtz (Tony Grove Cave Survey of the Utah Cave Survey), Brandon Kowallis, Max Barker, Vern Bowden (Idaho Cave Survey), and the Salt Lake Grotto for permission to use their cave maps in this publication as well as Jon Jasper for the use of his digitized cave data. Lastly, I would like to thank my committee members, Dr. W. David Liddell, Dr. Thomas E. Lachmar, and Dr. Robert Q. Oaks, Jr., for their expertise, support, and patience throughout the entire project. Kirsten Bahr vii CONTENTS Page ABSTRACT ....................................................................................................................... iii ACKNOWLEDGMENTS ................................................................................................. vi LIST OF TABLES ...............................................................................................................x LIST OF FIGURES .......................................................................................................... xii INTRODUCTION ...............................................................................................................1 General Statement ....................................................................................................1 Objectives and Hypotheses ......................................................................................2 Study Area ...............................................................................................................3 BACKGROUND .................................................................................................................6 Stratigraphy ..............................................................................................................6 Structure .................................................................................................................10 Overview of Karst Hydrology ...............................................................................15 Caves in the Tony Grove Study Area ....................................................................18 Previous Work .......................................................................................................19 Tony Grove Hydrology ..........................................................................................20 METHODS ........................................................................................................................23 Mapping .................................................................................................................23 Geologic Mapping .....................................................................................23 Fracture Mapping .......................................................................................23 Stratigraphic Section ..............................................................................................27