28. MINERALOGY AND GEOCHEMISTRY OF ALTERATION PRODUCTS IN LEG 81 BASALTS1 A. Desprairies and C. Bonnot-Courtois, Université de Paris-Sud

• Main Authors: C. Jehanno, Centre Des Faibles Radioactivités, S. Vernhet, Université De Paris-sud, J. L. Joron
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pala; Northeast Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.488.2558; http://www.deepseadrilling.org/81/volume/dsdp81_28.pdf

Alteration products of basalts from the four holes drilled during Leg 81 were studied and found to be characterized by the widespread occurrence of trioctahedral clay minerals (Mg smectite to chlorite). In some cases zeolites (analcite, chabazite) are associated with the saponite. A more oxidizing stage is marked by a saponite-celadonite association, pre-senting the geochemical characteristics of hydrothermal processes. Later stages of alteration are represented by pala-gonitization and subaerial weathering at two sites. These different alteration processes of basalts from Leg 81 record the paleoenvironment during the first opening stages of the Northeast Atlantic Ocean in the Paleocene-Eocene periods.