--> Abstract: Stochastic Modeling Of Chirp Sonar Facies: Quantification Of Processresponse Relationships On A Muddy Shelf, The Yellow Sea Continental Margin, by P. J. Pearce and L. R. Bartek, III; #90928 (1999).

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PEARCE, P. J., and L. R. BARTEK, III
Department of Geology, University of Alabama, Tuscaloosa, AL

Abstract: Stochastic Modeling of Chirp Sonar Facies: Quantification of ProcessResponse Relationships on a Muddy Shelf, The Yellow Sea Continental Margin

Approximately 5024 km of chirp sonar data collected in the Yellow Sea is being examined to determine depositional process-response relationships active in the basin from the late Pleistocene to the present. Seismic facies are objectively identifed, mapped, and interpreted in a sequence stratigraphic context to delineate contemporaneous depostional environments. Factor analysis, Markov chain analysis and ANOVA are used to produce a quantitative model of the statistically significant spatial and temporal distribution of seismic facies.

Preliminary seismic facies analysis of chirp sonar data reveals the presence of a regional irregular surface of locally high relief, interpreted as the oxygen isotope stage 2 sequence boundary. This surface shows evidence of erosional truncation of low amplitude, high frequency, laterally continuous, highstand deposits of oxygen isotope stages 3 or 5. The unconformity is overlain by laterally extensive chaotic and inclined facies that bears strong resemblance to seismic facies associated with lowstand braided fluvial deposits. The chaotic package is bounded above by a parallel, highly continuous surface with minor relief, and is interpreted as the first major transgressive surface. Above this surface, the uppermost facies are characterized by high to low amplitude parallel, continuous or reflection free facies that are interpreted as strata deposited via settling of sediment from suspension. This uppermost interval contains additional minor surfaces, probably indicating multiple transgressive events and has a trend of thickening to the northwest. Reflection terminations at the sea floor indicate recent, localized scour, probably associated with tidal currents.

Boundary conditions present in the Yellow Sea are analogous to foreland basin settings. Both are characterized by high sedimentation rates, shallow water depths, and close proximity to sediment sources. The quantitative and reproducible model produced in this investigation that relates processes to sedimentary facies for this set of depositional boundary conditions creates an opportunity to compare facies distributions produced in basins with different boundary conditions. These comparisons provide an opportunity to use relatively limited data sets to determine whether potential reservoirs exist in analogous basins.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas