Concentrations of trace elements and stable carbon and oxygen isotope record of carbonates of ODP Leg 103 holes (Table 1)

Trace element contents (Sr, Mg, Mn, and Fe) and the composition of oxygen and carbon isotopes show that late burial diagenesis did not play an important role in pelagic carbonate chemistry in the bulk carbonates recovered from Holes 638B, 638C, and 641C (except for anoxic pore-water diagenesis in Valanginian sediments). The evolution of these different geochemical markers documents the importance and global extent of the Barremian ocean chemistry crisis. A reconstruction of paleoceanographic and climatic conditions during the Early Cretaceous is proposed. Sea level rose eustatically from the early Hauterivian to early Albian, but a rapid down and up fluctuation occurred during the Barremian. Soluble supply from the continent decreased during the Valanginian-early Hauterivian while oceanic hydrothermal supply increased. The climate cooled slightly during the Hauterivian, rapidly warmed during the Barremian, and cooled again during the Aptian.