24. ORGANIC CARBON ACCUMULATION AT SOUTHEAST GREENLAND SITE 918: IMPLICATIONS ON PALEOENVIRONMENT AND PALEOCEANOGRAPHY DURING LATE CENOZOIC TIMES¹

Rainer Stax²

ABSTRACT

Site 918 was drilled in the western part of the Irminger Basin to sample sediments comprising major changes in paleoclimate and paleoceanography of the last 51 m.y. Organic geochemical investigations were performed to study the quality and quantity of organic matter within the distinct lithologic units. At Site 918, changes in the lithologic composition recognized in the sedimentary column correlate very well with changes in the organic fraction, which is used for paleoenvironmental reconstructions. The accumulation of organic carbon at Site 918 is mainly controlled by the interaction between surface-water productivity, bottom-water oxygenation, burial rates, and terrigenous organic supply. One of the main organic constituents is plant detritus deposited in preglacial times. Planktonic organic material dominates during glacial times (i.e., the last 5 m.y.).

¹Saunders, A.D., Larsen, H.C., and Wise, S.W., Jr. (Eds.), 1998. Proc. ODP, Sci. Results,152: College Station, TX (Ocean Drilling Program).
²Institute for Geology and Mineralogy, Erlangen University, Schloßgarten 5, 91054 Erlangen, Federal Republic of Germany. rstax@geol.uni-erlangen.de