Sedimentation on a Salt Substrate: New opportunities in sediment experiment with a polymer layer
Dr. Wonsuck Kim
Department of Geological Sciences
Jackson School of Geoscience, University of Texas at Austin
Subsidence resulting from differential sediment loading on a mobile substrate (e.g., salt) causes two-way interaction between sedimentation and subsidence, resulting in unique morphology and stratigraphy. This interaction occurs in various depositional environments, e.g. intraslope minibasins, terminal fans, clinoforms/deltas, and aeolian dunes. Polydimethylsiloxane (PDMS), a proxy for salt has been extensively used for salt tectonics and structural studies, and now brings a new opportunity to investigate the dynamic interaction between sedimentation and subsidence in laboratory experiments. The polymer has a viscosity of 2.5e4 Pas and behaves as a linear viscous fluid that is ideal for modeling the dynamics of wet salt deformation. The Morphodynamics and Quantitative Stratigraphy Research Group at the University of Texas, Austin recently conducted a series of experiments that develop self-organizing deltas/clinoforms/terminal fans, dunes, and minibasins on top of a PDMS layer. We present a synthesis of current experimental results and discuss new opportunities and challenges for the experimentalist community in sediment experiments with a mobile substrate. The initial experimental results show the effects of 1) salt thickness that strongly controls subsidence rate, 2) intermittent sediment transport that changes depth and width of the deposit, 3) a ratio of progradation to subsidence that determines planform shape and size of the deposit, and 4) spacing between depositional bodies that modifies subsidence rate of individual deposit bodies. New experiments will aid to understand complex interplay between sediment and salt tectonics and produce new models to interpret morphology and the sedimentary record in natural systems.
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