HR: 0800h
AN: PP41C-0689    [Abstracts]
TI: The Biomarker Inventory, Trace, and Source of Heinrich Events and Heinrich-type Layers (MIS 8-16) in the North Atlantic
AU: Hefter, J
EM: jens.hefter@awi.de
AF: Alfred-Wegener-Institute for Polar and Marine Research (AWI), Am Alten Hafen 26, Bremerhaven, 27568, Germany
AU: * Stein, R
EM: ruediger.stein@awi.de
AF: Alfred-Wegener-Institute for Polar and Marine Research (AWI), Am Alten Hafen 26, Bremerhaven, 27568, Germany
AU: Sinninghe Damsté, J S
EM: damste@nioz.nl
AF: Royal Netherlands Institute for Sea Research (NIOZ, Department of Marine Biogeochemistry and Toxicology, PO Box 59, Den Burg, Texel, 1790 AB, Netherlands
AB: Multiple cores from different locations in the North Atlantic were recovered during IODP Expeditions 303/306. We have investigated the biomarker distributions of identified Heinrich layers (HL) and ambient glacial/interglacial samples from Site U1305, located in the Labrador Sea in proximity to the former major iceberg discharge pathway derived via the Hudson Strait from the Laurentide-Ice-Shield (LIS).
A unique association of a multitude of "petrogenic" compounds such as benzohopanes, D-ring monoaromatic 8,14-secohopanes, rearranged diasterenes, mono- and triaromatic steranes, isorenieratene-derivatives as well as characteristic pristane/n- C₁₇ and pristane/phytane ratios ideally allows to distinguish organic matter from HL compared to adjacent samples. They therefore are regarded and can be used as organic-geochemical tracers not only for the occurrence of Heinrich Events of the last glacial cycle but also for older Heinrich-like events.
We present a biomarker based high resolution record of such events during a time interval from about 320-460 kyr at Site U1313 (MIS 10-12) and an extended record (MIS 8-16) of Heinrich-type events from Site U1308, i.e. from positions near the Mid-Atlantic Ridge and distal to the LIS.
In addition, the HL-specific biomarker association provides circumstantial evidence to derive from a relatively immature, Paleozoic marine rock deposited under occasional photic zone anoxic conditions, that is today located on the Laurentide/Canadian shield. Reinvestigation of available geologic and organic-geochemical data allowed narrowing down this assumed source to an Ordovician oil shale close to Hudson Strait, that indeed bears a striking resemblance in terms of biomarker distributions when compared to the specific association of compounds from samples of Heinrich Events.
DE: 1051 Sedimentary geochemistry
DE: 1055 Organic and biogenic geochemistry
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4924 Geochemical tracers
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting