Paleoenvironmental Interpretation of Tomboy Field, Offshore Western Niger Delta, Nigeria

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Author(s) S. O. Obaje | E. A. Okosun
Pages 628-638
Volume 2
Issue 9
Date September, 2013
Keywords Paleoenvironmental interpretation, Tomboy Field, western Niger delta, Nigeria

The aim of the study is to delineate the paleoenvironments of deposition in the study area using identified foraminifera specimens and lithofacies. The area of study is located in the Tomboy field of the offshore western Niger Delta area of Nigeria. The ratios between Textulariina, Miliolina and Rotaliina plotted in a foraminiferal morphogroup triangular cross-plot and the biometric analysis of foraminifera’s abundance and diversity indicated shelf paleoenvironment of deposition. Also, the ratio of planktic to benthic foraminifera (P/B ratio) of 25.92%/74.08% corroborated the paleodepths of inner to outer neritic (shelf) environment of deposition. In addition, the calculated average of 82.51%/17.49% percentage ratios of calcareous benthic to arenaceous benthic foraminifera (FOBC/FOBA) in the five wells indicated shallow marine paleoenvironment. Three paleodepths of inner neritic, middle neritic and outer neritic were characterised by indicator fossils such as Cassidulina neocarinata THALMANN, Textularia sp. DEFRANCE, Eponides eshira DE KLASZ & RÉRAT, Quinqueloculina seminulum LINNÉ, Uvigerina auberiana D’ORBIGNY, Ammonia beccarii LINNÉ, Nonionella sp., Globocassidulina subglobosa BRADY, Cancris auriculus FITCHTEL & MOLL, Amphicoryna scalaris caudata BATSCH, Spiroplectammina carinata CUSHMAN and Quinqueloculina microcostata NATLAND, Uvigerina peregrina CUSHMAN, Uvigerina subperegrina CUSHMAN & KLEINPELL, Bulimina aculeata BROTZEN and Florilus ex. gr. N. costiferum CUSHMAN, etc. Finally, the assessed lithofacies such as clay, silt, poorly to well sorted fine- to coarse- grained sands and the presence of fossil accessories such as micro-mollusc and echinoid remains, etc., also agreed with the paleodepths of inner neritic to outer neritic.

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