(Table T1) Major and trace element concentrations of fine-grained sediments of ODP Hole 210-1276A

Inorganic chemical composition and downhole variation of major and trace elements yields useful insights into the sediment provenance and paleoceanography of deep-sea sediments of deepwater continental margins. Here, fine-grained sediments were chemically analyzed at ~10-m intervals from the Eocene to Albian section at Site 1276. These sediments represent a time when background hemipelagic sedimentation was continuously beneath, or near, the calcite compensation depth (CCD). Additional samples were analyzed from the upper Paleocene-middle Eocene time interval to determine whether a volcaniclastic component is present, as suggested by petrographic studies of the coarser size fraction. Sediments recovered near the bottom of the hole show the effects of contact metamorphism adjacent to a sill of alkaline basalt. The overlying thick (~700 m) Albian succession (lithologic Unit 5) is indicative of a dominantly terrigenous source. Redox-sensitive trace elements (e.g., Cu, Ni, V, and Cr) are concentrated in organic-rich layers (black shales) that can be partially correlated with oceanic anoxic Events 1a-1d and 2. Beginning around the Cenomanian/Turonian boundary, a profound change took place to more oxidizing, slowly depositing sediments throughout the North Atlantic, characterized by relative enrichment in Fe, Mn, and related trace metals (e.g., Cu, Ni, and Cr). Similar background conditions persisted until the Eocene when local conditions at Site 1276 became more reducing, as indicated by more subdued colors and lower MnO contents. Moderate upwelling along the Newfoundland continental margin during the Eocene is suggested by the presence of relatively high values of silica coupled with opaline silica. Phosphate and associated trace elements (e.g., Ce and Y) are locally enriched, suggesting relatively high primary productivity. However, productivity was lower than on the conjugate Iberia margin at Deep Sea Drilling Project Site 398. Fine-grained terrigenous sediments at Site 1276 probably were mainly derived from the Grand Banks (e.g., Avalon uplift) and finally accumulated in deep water below the CCD mainly as mud turbidites and hemipelagites.