Tentative Revision of the Global Pliocene-Pleistocene Sequences Based on the Sequence Stratigraphy in the Gulf of Mexico
WORNARDT, WALTER W., JR., Micro-Strat, Inc. and Rice University, Houston, TX, and PETER R. VAIL, Rice University, Houston, TX
The Pliocene-Pleistocene sequence chronostratigraphy presented in our paper is based on a vast amount of data obtained from more than 100 wells drilled over the past eight years in the south additions and deep-water areas in offshore Texas and Louisiana, Gulf of Mexico. This high-resolution biostratigraphic data base consists of individual checklists with the abundance, diversity, occurrences, and ranges of planktonic and benthic foraminifers and calcareous nannofossils plotted against depth. The benthic foraminifers have been interpreted largely for their paleobathymetric significance and result in a water-depth curve for each well studied. These wells have been further calibrated by having a portion of the study wells tied to sequence stratigraphic interpretations of seismic record ections through a two-way-time log or synthetic seismogram.
The Pliocene and Pleistocene is tentatively divided into 14 fourth-order sequences from 3.0 to 0 Ma and three third-order cycles from 5.5 to 3.0 Ma. Each of the cycles is bounded by a sequence boundary and has an age-dateable maximum flooding surface. Depending on location, each sequence may have lowstand, transgressive, and highstand systems tracts within the basin. The age (Ma) of the sequence boundaries are third-order, 5.5, 4.2, 3.8, fourth-order, 3.0, 2.6, 2.4, 1.86, 1.4, 1.0, 0.82, 0.72, 0.62, 0.52, 0.42., 0.32, 0.22, 0.12, and 0.02. Within these sequence boundaries are the 5.0, 4.0, 3.4, 2.7, 2.45, 2.0, 1.47, 1.3, 0.92, 0.76, 0.66, 0.56, 0.46. 0.36, 0.26, 0.16, and 0.06 Ma maximum flooding surfaces, respectively.
All of the condensed sections associated with the maximum flooding surfaces, systems tract boundaries, and sequence boundaries in the Pliocene-Pleistocene can be recognized and traced on well logs and seismic record sections in the offshore Texas and Louisiana areas.
AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)