28. Mineralogy and geochemistry of alteration products in leg 81 basalts 1

A. Desprairies (1) , C. Bonnot-Courtois (1) , C. Jehanno (2) , S. Vernhet (1) , J.L. L Joron (3) , Laboratoire P Sue

1 UP11 - Université Paris-Sud - Paris 11
2 Centre des Faibles Radioactivités
3 LPS - Laboratoire Pierre Süe

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, presenting the geochemical characteristics of hydrothermal processes. Later stages of alteration are represented by palagonitization 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.

Domaines: Océan, Atmosphère; Interfaces continentales, environnement

A. Desprairies, C. Bonnot-Courtois, C. Jehanno, S. Vernhet, J.L. L Joron, et al.. 28. Mineralogy and geochemistry of alteration products in leg 81 basalts 1. Initial Reports of the Deep Sea Drilling Project, 81, U.S. Government Printing Office, 1984, ⟨10.2973/dsdp.proc.81.128.1984⟩. ⟨hal-03516507⟩