The Biomarker Inventory, Trace, and Source of Heinrich Events and Heinrich-type Layers (MIS 8-16) in the North Atlantic


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Jens.Hefter [ at ] awi.de

Abstract

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/<i>n</i>- C<sub>17</sub> 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.



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Conference (Poster)
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Not peer-reviewed
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Published
Event Details
Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract PP41C-0689..
Eprint ID
18327
Cite as
Hefter, J. , Stein, R. and Sinninghe Damsté, J. S. (2007): The Biomarker Inventory, Trace, and Source of Heinrich Events and Heinrich-type Layers (MIS 8-16) in the North Atlantic , Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract PP41C-0689. .


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