Compound-specific radiocarbon ages of alkenones reveal rapid bottom current induced lateral sediment transport in the Panama Basin


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Stephanie.Kusch [ at ] awi.de

Abstract

Radiocarbon ages of molecular fossils like haptophyte biomarkers (alkenones) in comparison to 14C contents of calcareous microfossils like foraminifera tests can be used to identify lateral sediment transport processes. Such transport processes are a very important mode of delivery of organic matter in the ocean and occur either prior to initial deposition or following resuspension events. Lateral sediment transport processes do not impair the stratigraphy but, if unrecognized, may lead to serious misinterpretation of proxy records due to their sensitivity to the effects of sediment focusing. In our study we present 14C data of phytoplankton derived biomarkers (alkenones), co-occurring foraminifer-tests and total organic carbon (TOC). Late glacial to Holocene sediments from nearby cores ME0005-24JC and core Y69-71 from the SW Panama Basin were analysed. The age-relationships between foraminifera and alkenones and TOC do not imply significant contributions of pre-aged material. Foraminifera and alkenones show good agreement throughout the whole core section with a maximum age offset of 250yrs BP for core ME0005-24JC and 200yrs BP for Y69-71 indicating no resuspension of pre-aged alkenones. The good temporal correlation of the marine sediment constituents and TOC of less than 400yrs BP for both cores does also show insignificant contribution of pre-aged terrigenous material. Considering results from the constant flux proxy 230Th of previous studies the laterally supplied material has not been eroded elsewhere but rather is transported by bottom currents rapidly after particle formation.



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Conference (Poster)
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Not peer-reviewed
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Published
Event Details
Gordon Research Conference Organic Geochemistry 2008, Holderness, NH, USA, August 3-8.
Eprint ID
19498
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Kusch, S. , Eglinton, T. I. , Mix, A. and Mollenhauer, G. (2008): Compound-specific radiocarbon ages of alkenones reveal rapid bottom current induced lateral sediment transport in the Panama Basin , Gordon Research Conference Organic Geochemistry 2008, Holderness, NH, USA, August 3-8 .


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