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1 13312 Lamplight Village Ave., Austin, Texas 78727; giovanni{at}austin.rr.com
2 Bureau of Economic Geology, The University of Texas at Austin, Austin, Texas 78713
3 Bureau of Economic Geology, The University of Texas at Austin, Austin, Texas 78713
Guglielmo received his Ph.D. from the University of California-Santa Cruz in 1991. A recipient of the UCSC Best Ph.D. Dissertation Proposal award and the University of California President's Post-Doctoral Fellowship, he joined the Applied Geodynamics Laboratory of the Bureau of Economic Geology in 1993 where he was a research associate. Examples of his research are at http://www.utexas.edu/research/beg/giovanni/.Vendeville received his Ph.D. from the Université de Rennes, France, in 1987. He specializes in experimental modeling of tectonic processes with emphasis on gravity tectonics, salt tectonics, and extensional tectonics. He was the co-recipient of two honorable mentions from the SEPM/AAPG (1993) and AAPG (1990) with Martin P. A. Jackson. He is currently a research scientist at the Bureau of Economic Geology, the University of Texas at Austin.
Martin Jackson's early career included lunar structures, mineral exploration, and Precambrian geology. He received his Ph.D. from the University of Cape Town in 1976 and joined the Bureau of Economic Geology in 1980, where he directs the Applied Geodynamics Laboratory. A recipient of AAPG's Sproule Award (with S. J. Seni), Matson Award, and Dott Award, he lectured in AAPG's Structural Geology School, was an AAPG Distinguished Lecturer, and served six years as Associate Editor for the AAPG Bulletin and GSA Bulletin.
Palinspastic restorations elucidate geologic and hydrocarbon-migration histories in salt provinces; however, salt dissolution and salt flow in and out of the section plane make it difficult to determine the shape of salt bodies before deformation, which hampers accurate restorations. Three-dimensional computer visualization of a physical model and analysis of isochores provide clues to the original shape of allochthonous salt bodies that were emplaced during extension and later compressed.
Initially, tabular salt (simulated by viscous silicone) was regionally extended as synkinematic sediments accumulated. Extension triggered the rise of reactive salt walls that subsequently were shortened coaxially. Contraction produced curvilinear faulted folds, pop-ups, detachment anticlines, and pinched-off salt walls. Salt was squeezed to higher levels through fault-bounded vents in the roof. Three generations of stacked salt sheets were extruded and later acted as structural detachments.
Isochore plots in the overburden show how patterns of sedimentation, deformation, and underlying salt changed through time. Isochores of prekinematic strata recorded only strain, with thinned belts recording early extension and paired, thickened belts recording late shortening. In contrast, isochores of synkinematic strata recorded mostly deposition on exposed structures, with thicks recording salt expulsion, block grounding, and roof collapse and thins recording diapir rejuvenation. Synkinematic isochores also recorded the former shape of subsequently shortened allochthonous salt, showing palinspastically how the weaker salt absorbed much more shortening than the stronger sediments encasing it. Isochore analysis thus improves two-dimensional and three-dimensional restorations of salt tectonics.
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  E. Roca, M. Sans, and H. A. Koyi Polyphase deformation of diapiric areas in models and in the eastern Prebetics (Spain) AAPG Bulletin, January 1, 2006; 90(1): 115 - 136. [Abstract] [Full Text] [PDF]
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