Title

Palynostratigraphy, Palynofacies and Thermal Maturation of Cretaceous-Paleocene Sediments from the Côte D'Ivoire-Ghana Transform Margin

Abstract

Cretaceous to Paleocene sediments from Ocean Drilling Program Sites 959 to 962 in the Cote d'Ivoire-Ghana Transform Margin yield a rich assemblage of dinoflagellate cysts, few acritarchs, spores and pollen, and 12 types of dispersed organic matter. Dinoflagellate cysts proved invaluable in the refinement of shipboard-generated age determinations for Turonian to Paleocene sediments and identification of the Cretaceous/Paleocene boundary at Site 959. A few spore and pollen taxa are of stratigraphic significance. All but two samples of the tectonized basal siliciclastic sediments are barren of dinoflagellate cysts at Sites 959 and 960, but a few samples yield a very low diversity assemblage of spores and pollen. Palynofacies analysis indicates that amorphous organic matter is the dominant organic component in the sediments. However, the tectonized siliciclastic sedments are richer in identifiable terrestrially derived components (wood, black debris, and cuticles) or amorphous organic matter of terrestrial origin. Samples immediately below post-Albian unconformity surfaces at Sites 959 to 961 are enriched in wood and black debris. Thermal alteration indices (TAI) were derived from semiquantitative assessment of spore and pollen colors and used to interpret the thermal maturation of the sediments. TAI values indicate (1) a mature to overmature stage (values >2.5, occasionally dark) for the tectonized basal siliciclastic sediments at all four sites; (2) a moderately mature stage (2-2.5) for some Upper Cretaceous sediments at Sites 959, 960, and 962; and (3) an immature stage (<2) for the rest of the stratigraphic section. The most mature sediments were deposited during the syntransform phase of basin evolution.

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Cretaceous; Paleocene; Thermal Maturity

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1998 Elsevier, All rights reserved.

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