ZHANG, JIE, Department of Oceanography, Texas A&M Univ., College Station, TX; J. S. WATKINS, Department of Geophysics, Texas A&M Univ., College Station, TX; J. P. SHYU, Department of Oceanography, Texas A&M Univ., College Station, TX

ABSTRACT: Plio-Pleistocene Seismic Sequence Analysis, Outer Shelf and Upper Slope, Central Offshore Louisiana, Gulf of Mexico

In the area, we identified nine 4th order sequences in the Plio-Pleistocene section using a combination of seismic, well log, and biostratigraphic data on a Landmark Workstation. The sequences are: DS(3.72 -- sequence order from Vail, 1991), DB(3.73), CM(3.81), SG(3.82 and 3.91), PAL(3.92), PA(3.93), PL(3.94 & 3.95), SA(3.96), EH(3.101), with maximum flooding surfaces respectively characterized by D. surculus, D. brouweri, C. macityrei, small Gephyrocapsa, P. lacunosa B, P. lacunosa A, P. lacunosa, "Sangamon", E. huxicyi. All abundance peaks correspond well with condensed sections. Each sequence is characterized by a succession of four different facies on well logs and seismic data. One or more high amplitude, continuous reflectors representing the basin floor fan is found in all equences. Above these are leveed channel complexes or chaotic facies which correspond to slope fans. The third facies consists of semi-continuous-to-discontinuous low-to-moderate amplitude reflectors which represent lowstand prograding complexes. Transgressive systems tracts, condensed sections and the highstand systems tracts occur at the top of the sequence. Transgressive systems tracts are characterized either by transparent reflections or are too thin to separate from the underlying systems tracts. Condensed sections are evidenced mainly by semicontinuous-to-continuous, low-to-moderate amplitude reflectors. Most growth faults were initiated by salt movement. Lowstand sediments onlap the flank of salt structures. Transgressive system tracts, highstand systems tracts, and parts of prog ading wedges may locally drape tops of salt structures.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana