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Environmental Geosciences (DEG)

Abstract

Environmental Geosciences, V. 20, No. 1 (March 2013), P. 17–29.

Copyright copy2013. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

DOI: 10.1306/eg.10231212008

New constraints on buried Triassic basins and regional implications for subsurface CO2 storage from the SeisData6 seismic profile across the Southeast Georgia coastal plain

Olusoga M. Akintunde,1 Camelia C. Knapp,2 James H. Knapp,3 David M. Heffner4

1Department of Earth and Ocean Sciences, University of South Carolina, Columbia, South Carolina; [email protected]
2Department of Earth and Ocean Sciences, University of South Carolina, Columbia, South Carolina; [email protected]
3Department of Earth and Ocean Sciences, University of South Carolina, Columbia, South Carolina; [email protected]
4Department of Earth and Ocean Sciences, University of South Carolina, Columbia, South Carolina; [email protected]

AUTHORS

Olusoga M. Akintunde did this work as part of his Ph.D. at the University of South Carolina. He received his M.S. degree in geophysics from Stanford University, and his M.Tech. in exploration geophysics and B.Tech. in applied geophysics from the Federal University of Technology, Akure, Nigeria. His research involves seismic imaging, rock physics, and petrophysics for subsurface characterization and fluid monitoring.

Camelia C. Knapp is an associate professor of geophysics at the University of South Carolina. Her areas of research involve active source seismology for applications in petroleum exploration, marine gas hydrates, and subsurface characterization for CO2 storage. She received her B.S. degree in geophysical engineering from the University of Bucharest, Romania, and her Ph.D. in geophysics from Cornell University.

James H. Knapp is a professor of geology and geophysics at the University of South Carolina. His research interests are in regional tectonics, structural geology and basin analysis for applications in hydrocarbon exploration, subsurface CO2 storage, and characterization of gas hydrate reservoirs. He received his B.S. degree in geology from Stanford University and his Ph.D. in structural geology and tectonics from Massachusetts Institute of Technology.

David M. Heffner is a Ph.D. candidate at the University of South Carolina. He earned an M.S. degree in geological sciences from the University of South Carolina, and a B.S. degree in computer science and a postbaccalaureate major in earth and environmental science from Furman University. His research focuses on the rift tectonics of the southeastern North American margin.

ACKNOWLEDGEMENTS

We thank our colleagues John M. Shafer, Mike Waddell, Adrian Addison, Duke Brantley, and Mark Evans from the Earth Sciences Resources Institute, Columbia, South Carolina, for their contributions toward this work. We also thank Bill Clendenin and Scott Howard of the South Carolina State Geological Survey for providing valuable references and helpful discussions on the South Georgia Rift basin. Dr. Pradeep Talwani, an emeritus professor at University of South Carolina–Columbia, provided helpful feedback on the manuscript. We thank the DEG editorial board and the two reviewers for their excellent reviews. The well logs used for this study were provided by the Southern Company based in Georgia. The S6 line was licensed and made available by Geophysical Pursuit, Inc. We thank Landmark Graphics, Inc., for providing the ProMAX 2-D seismic processing and analysis software. This material is based on a work supported by the U.S. Department of Energy under award number DE-FE0001965.

This paper was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.

ABSTRACT

Reprocessing of the SeisData6 coastal plain profile was motivated by the need to provide enhanced subsurface imaging critical to site characterization studies for CO2 storage within the South Georgia Rift (SGR) basin. The objectives were to identify and interpret subsurface reflectors for evidence of the buried Triassic basin and its underlying characteristics. Our new interpretation, supported by analysis of well data, has helped substantiate the presence of a Triassic basin beneath the coastal plain sediments in Southeast Georgia. This basin is approximately 2.2 km (1.7 mi) deep and 170 km (106 mi) wide and appears to coincide with the subsurface convergence of the southwest and northeast extensions of the Riddleville and Dunbarton basins that are subsidiaries of the main SGR. It is characterized by distinctively higher seismic velocities relative to the overlying coastal plain sediments and manifests a series of subhorizontal reflectors below the topmost reflector. We reinterpreted the topmost reflector to originate from a change in velocity and density between the Cretaceous coastal plain sediments and the underlying Triassic rocks. This does not always originate from the Pre-Cretaceous basalt contrary to previous interpretations. The interpreted absence of basalt from this study is consistent with Heffner et al. (2012) showing that basalt is not prevalent throughout the SGR basin. Seismic discontinuities in the southeast of the basin suggest Triassic normal faults. Our data show no clear evidence for the Augusta fault that was identified in other studies in the vicinity of the Piedmont–coastal plain boundary in Georgia and South Carolina.

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