Jurassic-Cretaceous Stratigraphic and Structural Evolution of the Northern Yucatan Margin, Gulf of Mexico Basin
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JURASSIC-CRETACEOUS STRATIGRAPHIC AND STRUCTURAL EVOLUTION OF THE NORTHERN YUCATAN MARGIN, GULF OF MEXICO BASIN ---------------------------------------------------------------- A Thesis Presented to the Faculty of the Department of Earth and Atmospheric Sciences University of Houston ---------------------------------------------------------------- In Partial Fulfillment of the Requirements for the Degree Master of Science ---------------------------------------------------------------- By Andrew Steier May 2018 JURASSIC-CRETACEOUS STRATIGRAPHIC AND STRUCTURAL EVOLUTION OF THE NORTHERN YUCATAN MARGIN, GULF OF MEXICO BASIN ________________________________________ Andrew Steier APPROVED: ________________________________________ Dr. Paul Mann, Chairman ________________________________________ Dr. Jonny Wu ________________________________________ Ted Godo, Murphy Oil Corporation ________________________________________ Dr. Dan Wells, Dean College of Natural Sciences and Mathematics ii ACKNOWLEDGEMENTS I would like to thank my research advisor, Dr. Paul Mann, for his guidance during my time at the University of Houston (UH), first as an undergraduate research assistant from 2015 to 2016 and then as a graduate student from 2016 to 2018. It was thanks to his academic guidance and his industry connections that I was able to gain valuable technical skills and access to a proprietary seismic dataset that set me apart from other students competing for jobs in the oil and gas industry. Truly, I would not be in the professional situation I am today without the support of Dr. Mann. Special thanks also go to Dr. Jonny Wu and Ted Godo, whose enthusiasm and thoughtful recommendations greatly improved this thesis. And I would like to thank Dr. Shuhab Khan, who in his role as the UH Undergraduate Advisor directed me to potential research advisors when I first arrived at UH as a lost post-baccalaureate student. Thanks also go to those involved with the Conjugate Basins, Tectonics, and Hydrocarbons (CBTH) research consortium. This includes the corporate sponsors whose financial support funded my graduate studies and the company representatives who provided feedback on my project at various stages. I specifically would like to thank Mike Saunders and Laurie Geiger of Spectrum Geo for making the seismic data available to me for this study and the US and Mexican Gulf of Mexico teams at Total for helpful feedback that improved this thesis. Finally, I would like to thank the other CBTH students, both past and present, for their assistance, encouragement, and friendship during my time at UH. And personally, I would like to thank Elda Smith and Heather Anderson for originally encouraging me to pursue a career in geology. I would like to thank my family for encouraging me along the way while keeping me grounded in my overall career goals. And most of all, I thank my wife, Jennifer, who has been there every step of the way, listening with a patient ear to every frustration and sharing in every celebration. iii JURASSIC-CRETACEOUS STRATIGRAPHIC AND STRUCTURAL EVOLUTION OF THE NORTHERN YUCATAN MARGIN, GULF OF MEXICO BASIN ---------------------------------------------------------------- An Abstract of a Thesis Presented to the Faculty of the Department of Earth and Atmospheric Sciences University of Houston ---------------------------------------------------------------- In Partial Fulfillment of the Requirements for the Degree Master of Science ---------------------------------------------------------------- By Andrew Steier May 2018 iv ABSTRACT The Gulf of Mexico (GOM) basin formed during Triassic-late Jurassic rifting as the Yucatan continental block rifted to the southeast away from its northern GOM conjugate margin. During a second, late Jurassic-earliest Cretaceous drift phase, the Yucatan block rotated counter- clockwise to its current location and produced an eastward-narrowing wedge of oceanic crust beneath the central GOM. The stratigraphy and structural evolution of the Florida margin is much better understood than its northern Yucatan conjugate because previous hydrocarbon exploration has been more extensive on the Florida margin. In the northeastern GOM, the late Jurassic section near DeSoto Canyon records late Jurassic-Cretaceous gravity sliding of rafted blocks over distances of 25-40 km along a basinward-dipping layer of salt. This study uses a 117,000 km2 grid of 2D seismic data tied to published regional seismic lines and wells to describe a previously unrecognized and coeval area of widespread, gravity sliding along the less-studied, northern Yucatan margin. I define three structural domains based on their distinctive salt structures and associated deformation: 1) the northeastern study area consists of relatively undeformed, late Jurassic-Cretaceous section underlain by 0-300 m-thick salt; 2) areas in the central and southwestern study area contain late Mesozoic gravity slides defined by normal faults rooted onto a 1-4° basinward-dipping salt detachment that controlled overlying, sedimentary growth wedges separated by intervening, 300- 600 m-thick salt rollers; and 3) the distal margin of the western and central study area exhibits large salt diapirs up to 6 km tall that penetrate overlying units as young as the Pleistocene. In the central study area containing late Mesozoic gravity slides, a sedimentary unit equivalent to the productive, Oxfordian Norphlet sandstone of the deep-water northeastern GOM is identified based on its similar seismic character. Reconstructing the Norphlet-equivalent unit v to its location during Oxfordian deposition places it adjacent to an extensive area of deep-water Norphlet sandstone mapped in a previous study. The reconstruction suggests an 84,000 km2 fairway of potential aeolian, Jurassic reservoirs on the Yucatan and Campeche margins that includes areas of productive reservoirs in the southeastern Bay of Campeche which previous authors correlated with the Norphlet Formation. vi TABLE OF CONTENTS I. INTRODUCTION TO THIS THESIS………………………………………………………..1 II. JURASSIC-CRETACEOUS STRATIGRAPHIC AND STRUCTURAL EVOLUTION OF THE NORTHERN YUCATAN MARGIN, GULF OF MEXICO BASIN 1. Introduction…………………………………………………………………………………….3 2. Regional geologic setting 2.1 Tectonic evolution of the Gulf of Mexico…………………………………………….5 2.2 Structural settings of large gravity slides on the conjugate margins of the northeastern . Gulf of Mexico and the Yucatan margin of Mexico………………………………......9 2.3 Geologic setting of the Yucatan margin and the southern Gulf of Mexico..…….......11 3. Dataset…………………...………………………………………………………………..…...16 4. Structural and stratigraphic interpretation 4.1 Late Jurassic-Cretaceous seismic interpretation……………………………..……….18 4.2 Distribution of salt structures……………………………………………….………...24 4.3 Basement structure and the continent-ocean boundary……………………….………25 5. Structural evolution of the Yucatan margin 5.1 Cross-section restoration methodology………………………………………………28 5.2 Structural evolution of the northeastern Yucatan area with minimal salt……………31 5.3 Structural evolution of the central Yucatan area with prevalent salt rollers………....31 5.4 Structural evolution of the southwestern Yucatan area with widespread diapirism…37 6. Discussion 6.1 Timing of salt-assisted gravity sliding on the Yucatan margin and implications for . Gulf of Mexico basin evolution……………………………………………………...49 vii 6.2 Controls on post-salt sedimentation and structural evolution……...………………...59 6.3 Late Jurassic paleogeography and implications for hydrocarbon prospectivity……..62 7. Conclusions……………………………………………………………………………………64 8. References……………………………………………………………………………...……...68 viii Figure Captions Figure 1. The deep-water Gulf of Mexico (GOM) separates the passive margins of the Florida and Yucatan margins. The location of this study’s seismic dataset is shown in red with coverage extending from the Yucatan shelf into the deep-water GOM. Bathymetric contours are shown as blue lines at 500 m intervals……………………………………………………………………….4 Figure 2. A. The study area is shown on a basemap of the vertical gravity gradient from Sandwell et al.’s (2014) global gravity grid. Using this same grid, Nguyen and Mann (2016) mapped fracture zones and extinct spreading ridges (black) in the GOM and used their geometry to identify the Yucatan’s pole of rotation (blue) near northwest Cuba. Small circles (red) centered at the pole of rotation show the predicted opening directions for the GOM conjugate margins that include the study area of the Yucatan margin in Mexico. The mapped extent of Callovian salt on both conjugate margins is modified from Rowan et al. (2004) and is shown in pink. B. This tectonic reconstruction restores the Yucatan continental block to its paleo-position in late Jurassic time (Oxfordian; 161 Ma). During Oxfordian time, the Yucatan block transitioned from the northwest-southeast directed extension in the first phase of Triassic-middle Jurassic GOM opening to counter-clockwise rotation and seafloor spreading during the second, late Jurassic- earliest Cretaceous phase of GOM opening. During the Oxfordian, aeolian dunes of the Norphlet Formation were being deposited on both the Yucatan and northern GOM conjugate margins. The blue, dashed polygon represents the Balsas portal, which Mann et al. (2016) proposed was the entry point for Pacific seawater into the large sag basin that had formed by the end of the phase one rifting…………………………………………………………………………………………..7 Figure 3. A. A seismic cross-section from Pilcher et al. (2014) trending northeast-southwest,