BEAUBOUEF, RICHARD T., and CARLOS PIRMEZ
Exxon Production Research Co., Houston, TX

Abstract: Mixed Sand/Mud Submarine Fan Systems: Comparing the Amazon Fan to Intra-Slope Basin Fans of the Gulf of Mexico

Despite their differences in size and physiographic setting the Amazon Fan and Pleistocene intra-slope basin fans of the western G.O.M. show many similarities with respect to stratigraphic architecture and evolution. Based on seismic, sidescan sonar, log and core interpretation, the stratigraphy of these turbidite systems include: a) low amplitude, chaotic units corresponding to Mass Transport Complexes (MTC), b) high amplitude, continuous, onlapping reflection packages corresponding to Distributary Channel-Lobe Complexes (DLC), c) moderate amplitude, continuous reflection packages that thin, and downlap away from a central channel corresponding to Leveed Channel Complexes (LCC), and d) thin, high-amplitude, continuous and draping seismic events corresponding to hemipelagic Drape Complexes (DC). These seismic units occur between prominent surfaces of erosion and onlap interpreted as sequence boundaries. Recurrent vertical stacking patterns typically include, from base to top, MTC, DLC, LCC, and DC. We interpret the basal MTC, DLC, and LCC succession to represent the lowstand system tract and the DC to represent the transgressive and highstand systems tracts of a depositional sequence. Integral to the construction of these turbidite systems are channel networks that link and provide sediment to individual depositional complexes. Submarine base level and its relation to local changes in gradient also are important controls in the sediment distribution and evolution of both intraslope and margin fan systems. In response to changes in base level, channels either aggrade or incise seeking to achieve equilibrium with prevailing sediment gravity flows. Unraveling the architecture and sedimentary processes in these modern submarine fans through high-resolution datasets is key to enhance our ability to predict resevoir characterstics in subsurface from 3D seismic data.

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