Organic geochemical investigations were performed on sediments of Leg 130 to reconstruct the depositional environment of the Ontong Java Plateau. The Miocene to Quaternary sediments collected during the drilling campaign are characterized by extremely low organic carbon contents. As indicated by C/N ratios and Rock-Eval data, most of the organic matter is probably of marine origin. Based on mass-accumulation rates of organic carbon, the paleoproductivity for the Miocene-Pliocene and the late Pliocene-Pleistocene time intervals as well as the modern surface-water production were estimated. The productivity values of the surface sediments (25-59 gC/m2/yr) reflect the various influences of the equatorial upwelling cell on the different sites. The accumulation rates of organic carbon are generally low; however, they show a distinct increase at 8 Ma and a decrease at 2 Ma.

Supplement to: Stax, Rainer; Stein, Ruediger (1993): Long-term changes in the accumulation of organic carbon in Neogene sediments, Ontong Java Plateau. In: Berger, WH; Kroenke, LW; Mayer, LA; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 130, 573-584