26. COMPARATIVE LOGGING RESULTS IN CLAY-RICH LITHOLOGIES ON THE BARBADOS RIDGE 1

M.J. Jurado,2 J.C. Moore,3 and D. Goldberg 4

ABSTRACT

Logging-while-drilling (LWD) data and open-hole wireline logs were acquired during Ocean Drilling Program Leg 156 in the Barbados accretionary prism, through the décollement, and into the underthrusting plate. Analysis of the LWD data indicates that the logs are suitable for qualitative and quantitative interpretations, whereas the quality of the wireline logs was adversely affected by poor hole conditions during acquisition. Inversion on LWD data provide porosity and compositional models for the Leg 156 sites. A key question addressed is the effect of compositional and bound water on porosity estimates. The combined analysis performed on Hole 948A LWD density and neutron porosity logs and natural gamma-ray spectral data is used to study the effect of compositional and bound water from the log response. We found a qualitative correlation between LWD log response, physical property measurements, and compositional changes derived from cores. LWD data also reflect the main tectonic and stratigraphic features recognized at Site 948 and allow identification of similar features at Site 947.

1 Shipley, T.H., Ogawa, Y., Blum, P., and Bahr, J.M. (Eds.), 1997. Proc. ODP, Sci. Results,156: College Station, TX (Ocean Drilling Program).
2 Geophysikalisches Institut, Universität Fridericiana Karlsruhe, Hertzstrasse 16, 76187 Karlsruhe, Federal Republic of Germany. mjjurado@ija.csic.es
3 Earth Sciences Department, University of California, Santa Cruz, Santa Cruz, CA 95064, U.S.A.
4 Borehole Research Group, Lamont Doherty Earth Observatory, Columbia University, Palisades, NY 10964, U.S.A.