--> Abstract: Calcareous Nannofossil Biostratigraphy and Abundance Patterns in Northern Central Gulf of Mexico, Offshore Louisiana, by J-P. Shyu and J. S. Watkins; #91012 (1992).

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ABSTRACT: Calcareous Nannofossil Biostratigraphy and Abundance Patterns in Northern Central Gulf of Mexico, Offshore Louisiana

SHYU, JIH-PING, and JOEL S. WATKINS, Texas A&M University, College Station, TX

Calcareous nannofossils from eight wells in Green Canyon, Eugene Island South Addition, and Ship Shoal South Addition areas have been studied. The main objectives of this study are to delineate condensed sections from nannofossil checklists and abundance patterns and to study their relationships with depositional environment.

Altogether, 26 condensed sections have been identified in the middle Miocene to Pleistocene sequences. The youngest condensed section was characterized by the lowest occurrence of Emiliania huxleyi (0.275 Ma). The first downhole occurrences of predominant small Gephyrocapsa and Helicosphaera sellii are often found together in the 0.9 Ma condensed section, which could be due to the occurrence of hiatus or reduction in sediment accumulation rate. Results of this study correlate well with other published data but show more detail in the upper Pleistocene, lower Pliocene, and Miocene.

Redeposited nannofossils are more abundant in the upper Pleistocene than in the older sediments. This mainly reflects shifts in depocenters. Patterns of redeposited nannofossil abundance are generally inversely correlative with patterns of indigenous nannofossils. Redeposited nannofossil abundance peaks are not as useful as indigenous nannofossil abundance peaks, but some could help in local correlations.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)