The California Current and associated coastal upwelling have changed with the growth and decay of the North American ice sheets since 2.5 Ma. Because the coastal upwelling has a close relationship with biogenic productivity in surface water, analyses of biogenic components in sediments of the upwelling region enable us to reconstruct the past changes of the productivity and/or the current systems.In this study, we analyzed biogenic silica and carbonate as well as organic carbon in sediments from the northern California margin, Hole 1020B. The results show that terrigenous-free content of biogenic silica is high during interglacial periods since 800 ka and varies in correspondence with 100-k.y. glacial-interglacial cycles. On the other hand, terrigenous-free content of biogenic carbonate is high during glacial periods. These temporal variations may have been caused by changes in the origin of deep water.

DEPTH, sediment is given in mbsf.

Supplement to: Kuroda, Tomoko; Sakamoto, Tatsuhiko; Koizumi, Itaru (2000): Data Report: Temporal variations of biogenic components on the northern California margin since the late Pleistocene, Site 1020. In: Lyle, M; Koizumi, I; Richter, C; Moore, TC Jr (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 167, 1-4