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ABSTRACT: Taxonomy and Paleoecology of the Marginulina Zone, Cameron and Calcasieu Parishes

DESSELLE, BRUCE ALLEN, Consulting Geologist and Paleontologist, Metairie, LA

A total of 168 benthonic foraminifera are noted from five wells in Cameron and Calcasieu parishes with the intention of interpreting the paleoecology and taxonomy of the upper Oligocene Marginulina zone. Sixteen undescribed benthonic species or morphotypes of previously described species are present.

Well cuttings from the five wells were analyzed at 30-ft intervals. The study wells are oriented in a northeast-southwest transect approximately paralleling the paleocoast line.

Paleoecological interpretations were made by analyzing nonspecific (species diversity, planktonic:benthonic ratio, etc.) and specific (morphological variation, species predominance, etc.) faunal characteristics. These quantitative and qualitative faunal characteristics indicate that deposition of the Marginulina sediments occurred at a minimum depth indicative of present-day outer neritic environments. Deposition may have occurred at greater depths because nonspecific and specific faunal characteristics are indicative only of upper depth limits. The toxonomic study was fundamental to the paleoecologic analysis.


AAPG Search and Discovery Article #91014©1992 AAPG GCAGS and GC-SEPM Meeting, Jackson, Mississippi, October 21-23, 1992 (2009)