W0262

Characterization of Sediments from the Ocean Floor of the Venezuelan Atlantic Front using X-Ray Powder Diffraction Techniques. C. Cedeño, R. Toro, A. Vivas, D. Rosales, M. Romero, J. Contreras, G. Díaz de Delgado, J.M. Delgado, Laboratorio de Cristalografía-LNDRX, Depto. de Química, Fac. de Ciencias, Universidad de Los Andes, Mérida, Venezuela.

Our research group has undertaken the study of ocean floor sediments by X-ray powder diffraction techniques as part of a geological and environmental study of the Venezuelan Atlantic coast promoted and financed by PDVSA-INTEVEP, the Venezuelan National Oil Consortium. X-ray powder diffraction patterns were recorded using a Philips PW1250 goniometer automated by Crystal Logic, Inc., with CuKα radiation, variable divergence slit from 0-1 mm and receiving and dispersive slits of 1 and 0.2 mm, respectively. The patterns were processed and analyzed with the package JADE 5.0 (MDI). Patterns were registered on specimens prepared from (a) bulk sediments, (b) after sieving through 150 and 200 mesh, (c) wash with 18 Ohm water, (d) treatment with acetic acid/sodium acetate buffer (pH 5, adjusted with HCl, in 18 Ohm water), (e) treatment with H₂O₂, and (f) treatment with methanol, to remove soluble salts, carbonates, organic matter, at different stages. The analysis of the powder patterns by search/match techniques using the ICDD Powder Diffraction File indicated the presence of minerals commonly found in ocean floor sediments: quartz, calcite, aragonite and several clay minerals (montmorillonite, chlorite, kaolinite, illite, etc.). Rietveld refinements were carried out in a good number of diffraction patterns. Details of the analysis and its results will be presented in this contribution.