Abstract: Interpreting Paleoenvironments in the Albian Pinda Formation, Cabinda, Angola, Using Palynologic and Petrographic Data

Gaponoff, Sharma L.; Anthony J. Lomando - Chevron Overseas Petroleum Co.; and Kelly Maguire - Red Rock Associates Ltd.

The Albian Pinda Formation of offshore Cabinda, Angola, contains significant petroleum reserves. High frequency cyclic mixed carbonate and siliciclastic lithologies were deposited in shallow, normal to restricted marine and coastal plain settings. Palynology data from continuous 60? cuttings composites was used to recognize large scale sequential changes in environmental conditions. This gives accurate environmental determination in combination with petrography and wireline logs.

Palynology data was Interpreted using two separate statistical approaches to illustrate transgressions, regressions and paleoecological events. The first compares changes in frequency of taxa occurrence within six defined ecological groups. The second, Detrended Correspondence Analysis, compares presence/absence with relative abundance of respective taxa, resulting In paleoecologically related groups.

Results provide excellent correlation between environmental determinations from this statistical palynology approach and facies Interpretations from thin section petrography, and provide decisive evidence in ambiguous lithologies. This type of interdisciplinary approach strengthens our recognition of paleobiological and lithological responses to paleoenvironmental and facies variations across the Pinda shelf. Improved confidence in a variety of geologic applications is achieved, which Include regional studies, paleoreconstructions, sequence stratigraphy and correlation across listric faults.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil