--> Abstract: Passive Continental Margins Intermittently Migrating Basinward Represent Regional Modifications to Plate-Tectonic Scale Processes, by A. Lowrie and D. T. King, Jr.; #90090 (2009).

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Passive Continental Margins Intermittently Migrating Basinward Represent Regional Modifications to Plate-Tectonic Scale Processes

Lowrie, Allen 1; King Jr, David T.2
1 Consultant, Picayune, MS.
2 Geology, Auburn University, Auburn, AL.

Previous work describing the northern Gulf of Mexico continental margin as intermittantly migrating basinward may be viewed alternatively as sub-plate tectonic motion. With this alternative 'margin tectonics', principal motion, driven by gravity and rifting, differs from that of North American Plate and influences from ground-level/seafloor to mantle. Rifted margins contain normal faults in both the sedimentary wedge and foundering continental crust. These extensional tectonics apparently provide much of the translational margin downslope migration. Energies applied to this rifted margin cover range from "geologically instantaneous events", to rapid, slow, and continuous. Instantaneous events arise from meteor impacts, earthquakes, silent and slow earthquakes, and rapid depositional episodes and is an event whose overall duration lasts 1/1,000th or less of the temporal span of those processes interrupted by the sudden occurrence. An actual seismic event lasts seconds to minutes with initial results of disturbance ending in months. Geologically "rapid" events may last circa a century to a millenium, for example, repeated volcanic/earthquake cycles. "Slow" energy episodes, with stresses from eustatic sea level and tectonic cycles and associated sediment transportations, could have ranges from millenia to millions years. "Continuous" energies arise from gravity. These energies and their interactions drive margin tectonics. With margin migrating irregularily and sediment accumulations and removals, trans-sediment wedge stress build-ups and decreases will modify basement crust/lithosphere, continental to oceanic, which in turn could influence semi-plastic mantle. Such a temporal and spacial sweep of interrelated geologic processes could change earth system processes and how they are modeled.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009