(Table 1) Geochemistry at DSDP Hole 76-534A

Mineralogical and geochemical investigations carried out on Callovian to upper Cenozoic basalt and sediments of Hole 534A are the bases for paleoenvironmental interpretations. The clay mineralogy primarily reflects events that occurred on the American continent (tectonics, morphology, alteration and pedogenesis, climate), except in the basalt and at the precise basalt/sediment contact where in situ alteration and local metamorphic effects exist. The inorganic and organic geochemistry mainly reflects the influence of and increasing distance from the spreading center during the first stages of sedimentation, the terrigenous influence from the Valanginian upward, and the bottom reducing or oxidizing conditions linked to the widening and deepening of the ocean affected by global tectonics.