16. LITHOLOGIC INTERPRETATION OF DOWNHOLE LOGGING DATA FROM THE CÔTE D’IVOIRE-GHANA TRANSFORM MARGIN: A STATISTICAL APPROACH¹

Carlos A. Gonçalves²

ABSTRACT

Downhole logging data determined during Ocean Drilling Program Leg 159 on the Côte d’Ivoire-Ghana Transform Margin correlate to a varying degree with lithological and structural features observed in core description. Statistical analysis, such as principal component analysis and non-hierarchical cluster analysis, has been employed to classify these data into lithologically similar groups to produce a statistically derived lithostratigraphy for the holes drilled.

The derived logstratigraphy is in good agreement with the lithostratigraphy defined from the study of core specimens conducted by the Shipboard Scientific Party, but also highlights some apparently anomalous sedimentary regions in the holes, which should be the focus for further examination. These regions, defined here as zones, are related either to lithological or petrophysical variations within the sediments.

¹Mascle, J., Lohmann, G.P., and Moullade, M. (Eds.), 1998. Proc. ODP, Sci. Results, 159: College Station, TX (Ocean Drilling Program).
²Laboratório de Engenharia e Exploração de Petróleo (LENEP-UENF), Macaé/RJ, Brazil. carlos@lenep.uenf.br