Wright State University CORE Scholar Browse all Theses and Dissertations Theses and Dissertations 2019 Investigating an Apparent Structural High in Seismic Data in North Terre Haute, Indiana, Through First-Arrival Traveltime Tomography and Gravity Analysis Daniel Grant Koehl Wright State University Follow this and additional works at: https://corescholar.libraries.wright.edu/etd_all Part of the Earth Sciences Commons, and the Environmental Sciences Commons Repository Citation Koehl, Daniel Grant, "Investigating an Apparent Structural High in Seismic Data in North Terre Haute, Indiana, Through First-Arrival Traveltime Tomography and Gravity Analysis" (2019). Browse all Theses and Dissertations. 2153. https://corescholar.libraries.wright.edu/etd_all/2153 This Thesis is brought to you for free and open access by the Theses and Dissertations at CORE Scholar. It has been accepted for inclusion in Browse all Theses and Dissertations by an authorized administrator of CORE Scholar. For more information, please contact [email protected]. INVESTIGATING AN APPARENT STRUCTURAL HIGH IN SEISMIC DATA IN NORTH TERRE HAUTE, INDIANA, THROUGH FIRST-ARRIVAL TRAVELTIME TOMOGRAPHY AND GRAVITY ANALYSIS A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science By DANIEL GRANT KOEHL B.S. Tennessee Technological University, 2017 2019 Wright State University WRIGHT STATE UNIVERSITY GRADUATE SCHOOL April 30, 2019 I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Daniel Grant Koehl ENTITLED Investigating an Apparent Structural High in Seismic Data in North Terre Haute, Indiana, Through First-Arrival Traveltime Tomography and Gravity Analysis BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science. _________________________________ Ernest C. Hauser, Ph D. Thesis Director _________________________________ Chad R. Hammerschmidt, Ph D. Chair, Department of Earth & Environmental Sciences Committee on Final Examination ______________________________ Ernest C. Hauser, Ph D. ____________________________ Doyle R. Watts, Ph D. ____________________________ David F. Dominic, Ph D. ____________________________ Barry Milligan, Ph D. Interim Dean of the Graduate School ABSTRACT Koehl, Daniel Grant, M.S., Department of Earth and Environmental Sciences, Wright State University, 2019. Investigating an Apparent Structural High in Seismic Data in North Terre Haute, Indiana, Through First-Arrival Traveltime Tomography and Gravity Analysis This study focuses on northern Terre Haute, Indiana, where seven 2D seismic reflection time sections were collected by CountryMark and donated to Wright State University. Geologically, the area is on the eastern margin of the Illinois Basin. Two of these seismic lines display significant relief along a continuous, high-amplitude horizon approximately 180 milliseconds in two-way traveltime depth. This horizon was previously interpreted by CountryMark to be a Silurian reef core of the type common in this region of the Illinois Basin; however, other seismic lines within the data set display no relief. Furthermore, borehole logs within the area show no such relief at the equivalent depth of around 1700 feet. Therefore, the apparent structural high is an artifact within the two seismic lines, and can be called velocity pull- up. Various analyses were conducted to examine the causes of this velocity pull-up. The near-surface, within this region, contains many surfaces that may give rise to a velocity pull-up, including (1) the layer of weathered Pennsylvanian bedrock; (2) the Mississippian-Pennsylvanian Unconformity; and (3) an unconformity within Pennsylvanian section. It is possible that each of these surfaces could have enough relief to induce the observed velocity pull-up, and these possibilities were evaluated utilizing a combined analysis of Bouguer gravity, first-arrival traveltime tomography, passive seismic, and well log correlation. These multiple analyses show there is no Silurian reef core but a more complex velocity-inducing feature from a combination of the Mississippian-Pennsylvanian Unconformity and a shallower paleovalley fill. iii TABLE OF CONTENTS Page LIST OF FIGURES ................................................................................................ vi LIST OF ACRONYMS .......................................................................................... ix 1.0 INTRODUCTION ............................................................................................ 1 1.1 Prologue ................................................................................................ 1 1.2 Purpose of Study ................................................................................... 1 2.0 GEOLOGIC SETTING .................................................................................... 4 2.1 General Description .............................................................................. 4 2.2 Stratigraphy of southwestern Indiana ................................................... 4 2.2.1 Ordovician ..................................................................... 4 2.2.2 Silurian ......................................................................... 5 2.2.3 Devonian ....................................................................... 7 2.2.4 Mississippian ................................................................. 8 2.2.5 Pennsylvanian ............................................................... 10 2.2.6 Quaternary Deposition .................................................. 11 3.0 NOTABLE RESEARCH .................................................................................. 13 3.1 General Description .............................................................................. 13 3.2 Velocity-Inducing Structures ................................................................ 13 3.2.1 Silurian Reefs ................................................................ 13 3.2.2 Pennsylvanian Channel-fill Sandstones ........................ 18 3.2.3 Mississippian-Pennsylvanian Unconformity ................ 21 4.0 METHODS ....................................................................................................... 23 4.1 Overview ............................................................................................... 23 4.2 Seismic Reflection ................................................................................ 24 4.2.1 Acquisition .................................................................... 24 4.2.2 Processing ..................................................................... 25 4.3 Seismic Data Reprocessing Method ..................................................... 27 iv 4.3.1 General Description ...................................................... 27 4.3.2 Geometry ....................................................................... 27 4.3.3 Preprocessing ................................................................ 33 4.3.4 Trace Editing ................................................................. 57 4.3.5 Geometry and First Break QC ...................................... 60 4.3.6 Initial Model .................................................................. 63 4.3.7 Forward Modeling Inversion ........................................ 67 4.4 HVSR .................................................................................................... 71 4.5 Gravity .................................................................................................. 73 4.5.1 Acquisition .................................................................... 73 4.5.2 Reduction and Residualization ..................................... 75 5.0 Discussion ......................................................................................................... 85 5.1 General Description .............................................................................. 85 5.1.1 Tomography Modeling ................................................. 85 5.1.2 Gravity Reduction and Residualization ........................ 92 5.2 Interpretation of Tomography ............................................................... 93 5.3 Possible Errors ...................................................................................... 97 5.4 Industry Implications ............................................................................ 98 6.0 Conclusion ........................................................................................................ 99 6.1 Summary ............................................................................................... 99 6.2 Future Work .......................................................................................... 99 References ........................................................................................................ 100 Appendix .......................................................................................................... 103 v LIST OF FIGURES Figure Page 1. Study Area ........................................................................................................ 2 2. Seismic Line CM69 .......................................................................................... 3 3. Seismic Line CM70 .......................................................................................... 3 4. Vigo County in the Illinois Basin ..................................................................... 4 5. Wabash Platform from Whitaker (1988) .........................................................