Depositional Processes and Evolution of an Upper Pleistocene Mississippi Fan Channel (0.7-0.6 Ma), Northern Deep Gulf of Mexico
Christopher H. Morton1 and Paul Weimer2
1 BP Exploration, Houston, Texas
2 University of Colorado, Boulder, Colorado
Mississippi Fan channel # 10, ca. 0.7-0.6 Ma, is located in the western Atwater Valley protraction area. A detailed interpretation of a 3-dimensional seismic data set, 5.5 mile by 11.5 mile, was conducted to evaluate the updip evolution of the channel-fill and associated sediments. The thick nature of the sequence, 800 meters and extreme amounts of lateral migration of the channel fill made this sequence ideal for studying depositional processes in detail.
Three main architectural elements are channel-fill, levees, and slides. Channel-fill sediments are characterized by high amplitude and sub-parallel reflections that are commonly one to three reflections in occurrence. Eleven discrete channels could be traced through the data set. Levees are characterized by lower amplitudes and are parallel to subparallel with an external wedge shape near the flanks of the channel and that taper away from it. Several erosional surfaces and subfacies (truncation surfaces, isolated high amplitudes, slides, and reflection free or extremely deformed zones) are present within the levee-overbank sediments that reflect the complex sedimentary processes within the levee. Slides are characterized by a variety of seismic facies and are distributed in many positions throughout the sequence. Externally they are rotated, faulted, folded, and thrusted sediments. Three types of slides are present within sequence 10; slides from levees into channels, slides within the levees away from the channels, and slides that deform portions of the entire levee. The complex juxtaposition of and evolution of facies have important implications for reservoir modeling and the development of submarine fan channels.
AAPG Search and Discovery Article #90032©2004 GCAGS 54th Annual Convention, San Antonio, Texas, October 10-12, 2004