--> Abstract: Roles of Geologic Processes along Passive Continental Margins Suggest Dynamic Interrelationships of Cause and Effect, by Allen Lowrie and David King; #90072 (2007)

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Roles of Geologic Processes along Passive Continental Margins Suggest Dynamic Interrelationships of Cause and Effect

Allen Lowrie1 and David King2
1Consultant, Picayune, MS
2Auburn University, Auburn, AL

Using what we know about geologic processes along passive continental margins, the northern Gulf of Mexico used as a proto type, provisional primary geologic processes, i. e., tectonics, sedimentation, compaction, fluid migrations, are listed as general headings with secondary sub processes beneath. Our goal is to envision all that may be functioning in a continental margin from sea floor to basement at any given moment from the present and in differing geologic situations such as those characterizing Late Tertiary sea level oscillations. Such a compilation or checklist facilitates analyses of a given environment, be that a local area within a regional synthesis. Ranges of rates at which a specific process may operate/function aids in the visualization/comprehension of the interlocking dynamics of process interaction.
Some processes may be labeled as "geologically instantaneous events." These events include meteorite impacts, earthquakes, slow/silent earthquakes, and rapid depositional episodes. For this discussion, let us define instantaneous as an event whose overall duration lasts 1/1000th of the temporal span of those on going processes interrupted by the sudden occurrence. For example, a specific chronostratigraphic sequence whose genesis took tens of thousands of years is affected by an earthquake. The actual seismic event may last seconds to a minute with the initial results of disturbance being terminated in at most a few months. The more leisurely and later dispersion of energy/impact/disturbance may appear to be an exponential decay.
The exponential decay may have far reaching, territorially and temporally, events, effects not studied in detail.
Numerous different instantaneous events each with its own associated exponential decay create a complex and even changing stress environment. Such a dynamic stress environment impacts the extant continental margin. These cumulative impacts, instantaneous and decaying, must drive much of the overall evolution of such a continental margin.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece