--> Abstract: Sequence Biostratigraphy, by P. R. Thompson and W. H. Abbott; #90987 (1993).

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THOMPSON, PETER R., and WILLIAM H. ABBOTT, ARCO Exploration and Production Technology Company, Plano, TX

ABSTRACT: Sequence Biostratigraphy

Geologists seek patterns from maps and cross sections; biostratigraphers usually provide checklists and range charts. When the geologist asks for the environment of deposition he is given a paleobathymetry. If the interpreter talks about "time," does he want a geological age or a seismic velocity? We can no longer spend our time quietly putting names on objects: we must integrate our observations so that the geologist can make an informed decision.

The geological investigation of a seismic line is known as Sequence Analysis; the paleontological evaluation of geological ages and depositional settings is here termed Sequence Biostratigraphy. Display the results of the normal fossil census as a depth-scaled plot with curves of relative and absolute abundance, simple diversity, and cumulative frequency versus coarse fraction mineralogy. Suggest lithology with wireline logs such as gamma ray, spontaneous potential, resistivity or induction; annotate samples which contain glauconite, mica, or shell-hash. Stratigraphic units and ages on one side of the plot, a coastal onlap curve on the other side, and the judicious use of color throughout, all help the non-biostratigrapher "see" the interpretation.

Two geological time-slice maps can be generated for each depositional sequence: the relative regression and the later maximum flooding. Use color or patterns to delineate shallow to deep bioacies that suggest lithofacies. Superimposed, the maps suggest areas where reservoir-proneunits are sealed by impervious ones.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.