--> Sequence Stratigraphy in Structurally Complex areas: Integration of Multidisciplinary Data Sets, Columbus Basin, Trinidad, by L. Wood, M. Henry, B. Lanan, L. Spencer, P. Belanger, K. Ortmann, N. Engelhardt-Moore, D. Pocknall, and T. Romero; #90986 (1994).

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Abstract: Sequence Stratigraphy in Structurally Complex areas: Integration of Multidisciplinary Data Sets, Columbus Basin, Trinidad

L. Wood, M. Henry, B. Lanan, L. Spencer, P. Belanger, K. Ortmann, N. Engelhardt-Moore, D. Pocknall, T. Romero

Sequence stratigraphic techniques have revolutionized the way stratigraphers map and correlate strata. However, in non-passive margin basins explorationists often abandon sequence stratigraphic models due to multiple variables complicating development of basin stratigraphy. Developing accurate geologic models in such areas requires the integration of multidisciplinary data sets. Such a data set, including well logs, palynology, micropaleontology, oxygen isotopes, lithologic samples and seismic, was used to develop a geologic model for the Pliocene-Pleistocene deposits of the Columbus basin, Trinidad.

The Columbus basin is located off the eastern coast of Trinidad and the northeastern coast of Venezuela, along the margins of the converging Caribbean and Atlantic plates. Post-Miocene tectonics have resulted in transpressional structures oriented NE-SW and tensional faults oriented NW-SE. Sea level has undergone high frequency fluctuations throughout the Plio-Pleistocene. The Orinoco River, which drains the Andean Highlands, has fed enormous quantities of sediment into the basin since the late Miocene (>25,000 ft) inhibiting the presence of nannofossils and planktonic forams which are used in other basins for chronostratigraphic correlation. All of these variables have interacted to generate a complicated basin stratigraphy whose history is difficult to resolve, therefore multidis iplinary data were integrated to deconvolve the influence of climate, tectonics and sea-level change on the sedimentary record.

Large, regional faults influence the development of stratigraphic sequences by generating accommodation space resulting in significant cross-fault expansion of section (+/- 5,000 ft per fault). Sequences deposited during periods of active tectonics are characterized by rapid facies changes across the study area, while sequences deposited during periods of tectonic quiescence are characterized by lateral continuity of facies. Paleoclimatic events, interpreted from terrigenous palynomorphs and isotope data, correspond to episodes of shoreline translation. Faunal distribution and isotope data indicate water depth fluctuations and turbidity changes associated with active tectonics, shoreline translation and Orinoco River proximity.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994