LATE QUATERNARY HIGH-RESOLUTION BIOMARKER AND OTHER SEDIMENTARY CLIMATE PROXIES IN A NORTHEAST ATLANTIC CORE

We studied variations in terrigenous input and sea surface temperature over the last 208 ka using a multiproxy approach, involving direct co mparison of terrigenous and marine molecular biomarker, foraminiferal abundance, and other sedimentological data for the same horizons in a single northeast Atlantic core (core T88-9P; 48 degrees 23' N, 25 degr ees 05' W, 3193 m water depth, 790 cm core length) with a well-resolve d delta(18)O stratigraphy. The abundances of three land-derived, long- chain compound classes, the n-alkanes (C-27, C-29, and C-31), the n-al kanoic acids (C-24, C-26, and C-28), and the n-alkanols (C-24, C-26, a nd C-28) show glacial/interglacial related changes in the past 208 ka which generally parallel the weight percent noncarbonate. The abundanc es of these three compound classes are higher in glacial than in inter glacial sediments. Such changes are consistent with the expected highe r dust inputs during glaciations as well as enhanced advection of part iculate matter in current systems. Ice-rafted debris (Heinrich events) may also contribute to the terrigenous biomarker record. The sea surf ace temperature (SST) signals derived from the alkenone unsaturation i ndex (U-37(K')) give an average SST during interglacial periods of 13 degrees C, which is about 3-4 degrees C higher than the average glacia l SST estimate. The U-37(K')-derived SST values dropped markedly in so me Heinrich layers, while sometimes leading the onset of the layer; th e percent Neogloboquadrina pachyderma(s), which is another frequently used qualitative temperature proxy, generally shows maxima coinciding with the layers. Our results show that most Heinrich layers were produ ced during times of intensely cold waters in the eastern North Atlanti c. They demonstrate that sufficient alkenones are present in the sedim ents for alkenone stratigraphy to be used as a tool for the assessment of short-term variations in sea surface temperatures even in these ol igotrophic North Atlantic waters.