CHEMOSTRATIGRAPHY AND GEOCHEMICAL CONSTRAINTS ON THE DEPOSITION OF THE BAKKEN FORMATION, WILLISTON BASIN, EASTERN MONTANA AND WESTERN NORTH DAKOTA by DAVID NYRUP MALDONADO Presented to the Faculty of the Graduate School of The University of Texas at Arlington in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN GEOLOGY THE UNIVERSITY OF TEXAS AT ARLINGTON December 2012 Copyright © by David Nyrup Maldonado 2012 All Rights Reserved ii Acknowledgements First, I would like to thank God for allowing me to return to school to finalize what has been a long and overdue achievement. I agree with the statement that timing is everything but hard work and perseverance played a very large role in completing this task. I would like to thank my advisor, Dr. Harry Rowe, for his patience, time, and energy during my attendance at the University of Texas at Arlington as a graduate student. This thesis would not have been possible without Dr. Rowe, Dr. Stephen C. Ruppel, and the Texas Bureau of Economic Geology in Austin, Texas. I would also like to extend thanks to Dr. John S. Wickham for his guidance and being a member of my thesis committee. I would also like to extend many thanks for Paula Burkhart our geoscience administrative assistant for her patience and understanding. I would also like to thank several members of the Texas Bureau of Economic Geology. I would also like to thank Kenneth Edwards and Josh Lambert for core handling assistance. I would also like to thank Brigham Exploration Inc., now Statoil, for contributing their cores to the Texas Bureau of Economic Geology in Austin, Texas. I would like to thank my family for their loving support and encouragement during my studies during these last several years. Finally, I would like to dedicate my academic career to the people for which I have the most love and respect, my parents. December 5, 2012 iii Abstract CHEMOSTRATIGRAPHY AND GEOCHEMICAL CONSTRAINTS ON THE DEPOSITION OF THE BAKKEN FORMATION, WILLISTON BASIN, EASTERN MONTANA AND WESTERN NORTH DAKOTA David Nyrup Maldonado, MS The University of Texas at Arlington, 2012 Supervising Professor: Harold Rowe The late Devonian-early Mississippian Bakken Formation was deposited in a structural-sedimentary intracratonic basin that extends across a large part of modern day North Dakota, eastern Montana, and the southern portion of Canada’s Saskatchewan Province. The deposition of the Bakken Formation occurred during a fascinating period of geologic time that is linked to one of the five major mass extinctions. The occurrences of these mass extinctions are recorded worldwide as organic rich mud rocks similar to the ones found in the Bakken Formation. Collectively, the Bakken Formation consists of a middle dolomitic siltstone that is representative of a transgressive deposit and is bound by regressive organic rich mud rocks deposits that were influenced by rapid flooding events induced by the late Devonian-early Mississippian seaway. Geochemical proxies, total organic carbon and stable isotopic results that were recovered from four cores provide insight into the paleoenvironmental conditions during the deposition of the Bakken Formation. Geochemical analysis and interpretation of sample suites exhibit aggregate mineralogical composition from related shifts in elemental concentrations in weight percent (wt. %) consisting of magnesium (Mg), calcium (Ca), silicon (Si), iv aluminum (Al) and iron (Fe). The occurrence of chemostratigraphic shifts from concentrations of the Bakken Formation’s bulk rock mineralogical composition represent facies changes of sedimentary packages within the middle Bakken and are linked to dolomite, calcite, quartz, pyrite, and clay (mainly illite) content. Furthermore, geochemical proxies of redox sensitive elements expressed as enrichment factors (EF) brought insight into the redox conditions during deposition of the upper and lower Bakken shales across the Williston Basin (e.g., Mo, U, V, Zn, Ni, and Cu). Molybdenum-total organic carbon (Mo-TOC) relationships, established two separate anoxic episodes that are represented by the Bakken shales and also provided insight into the degree of basin restriction the Williston Basin experienced during late-Devonian-early Mississippian time. Observed geochemical Mo-TOC relationships from the Bakken shales display similar trends of basin restriction comparable to modern silled basin analogues, specifically the Cariaco Basin (Algeo et al. 2006). The elemental shifts from Mo-TOC vs. depth profiles, demonstrate that the Bakken shales were deposited under semi-restricted conditions. Furthermore, Mo-TOC relationships also inferred water mass residence times and variable hydrographic mixing from deep basin waters from the Williston Basin. TOC and stable isotopic composition of TOC (δ¹³C) from the Bakken shales were utilized as geochemical proxies to examine the change and distribution of organic matter across the Williston Basin. Lastly, stable isotopic composition of TOC results potentially demonstrate a blend of kerogen source formed from marine organic matter (plankton) and land-plant lipids based on previous studies. v Table of Contents Acknowledgements………………………………………………………………………………iii Abstract……………………………………………………………………………………………iv List of Illustrations……………………………………………………………………………….viii List of Tables……………………………………………………………………………………...xi Chapter 1 Introduction……………………………………………………………………………1 Purpose of Study………………………….……………………………………………………1 Previous Work…………………………………………………………………………………..2 Regional Geology………………………………………………………………………………6 Devonian-Carboniferous Paleoclimate……………………………………………………..18 Research objectives....................……………..………………………………….…………19 Chapter 2 Methods………….………………………………………………….….……………21 Core Data Acquisition……………………….……………………………….….……………21 Energy Dispersive X-ray Fluorescence (ED-XRF) Analysis….………………………….22 Mudstone Calibration of ED-XRF……………………….……………………….……….…24 Additional Geochemical Analysis……………………….………………………………..…27 Chapter 3 Results………………………………………….………………….………………...28 ED-XRF and Non-ED-XRF Data………………………………………….………………...28 Chemostratigraphic Applications……………………………….………….………………..28 Diagrams…………………………………………………………………………….…………29 Chapter 4 Discussion……………………………………………….………………….……….32 Major Elements……………………………………………………………………….……….32 Three Forks Formation……………………………………………………….……….32 Bakken Formation…………………………………………………………….……….44 vi Redox Indicators Geochemical Proxies.................................................................…....50 Basin Restriction (Mo/TOC) .................................................................….....................55 Organic Composition (TOC and Stable isotopes of Organic Carbon) ..........................66 Bakken Shale Kerogen type from δ13C.................................................................……69 Chapter 5 Conclusion...................................................……………………………………..75 Future Research..........................................................……………………………………78 References....................................................................…………………………………….79 Biographical Information...............................................................…...…………………….91 vii List of Illustrations Figure 1-1 Major Paleozoic structural trends ............................................................... ……7 Figure 1-2 Present day structural features, Western Interior, United States ...................... 8 Figure 1-3 Generalized regional Montana-North Dakota cross section A-A’ ...................... 9 Figure 1-4 Regional paleography and paleostructure ....................................................... 12 Figure 1-5 Regional paleography and paleostructure ....................................................... 16 Figure 1-6 Stratigraphic column of the Williston Basin and Bakken Formation ................ 17 Figure 2-1 Geographical location of cores in research study ........................................... 21 Figure 2-2 Overview of ED-XRF instrumentation ............................................................. 23 Figure 4-1 Chemostratigraphic profile of major elements Three Forks Formation and lower Bakken Formation from west to east %Al, %Fe, %Ca, %Mg, %Si/%Al and %Si ... 33 Figure 4-2 Interpreted Upper-Devonian lithofacies map Three Forks Formation ............. 34 Figure 4-3 Cross Plot of Core A of %Ti, Mo ppm, Rb ppm, V ppm, U ppm, Zr ppm and %K versus %Al .................................................................................................................. 36 Figure 4-4 Cross Plot of Core B of %Ti, Mo ppm, Rb ppm, V ppm, U ppm, Zr ppm and %K versus %Al .................................................................................................................. 37 Figure 4-5 Cross Plot of CoreC of %Ti, Mo ppm, Rb ppm, V ppm, U ppm, Zr ppm and %K versus %Al ........................................................................................................................ 38 Figure 4-6 Cross Plot of Core D of %Ti, Mo ppm, Rb ppm, V ppm, U ppm, Zr ppm and %K versus %Al .................................................................................................................. 39 Figure 4-7 Cross Plot for Core A of %Ca, %Mg, %Si, and %K versus %Al ..................... 40 Figure 4-8 Cross Plot for Core B of %Ca, %Mg, %Si, and %K versus %Al ..................... 41 Figure 4-9 Cross Plot for Core C of %Ca, %Mg, %Si, and %K versus %Al ..................... 42 Figure 4-10 Cross Plot for Core D of %Ca, %Mg, %Si, and %K versus %Al ..................