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Major and minor element signatures of OC-rich Paleogene sediments from Lomonosov-Ridge (IODP Leg 302)

Fachliche Zuordnung Paläontologie
Förderung Förderung von 2005 bis 2010
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 12877501
 
Erstellungsjahr 2012

Zusammenfassung der Projektergebnisse

The major findings of this project and their value for the broader understanding of the Arctic Ocean are: • The organic-rich, biosiliceous Eocene sediments recovered from the Arctic Lomonosov Ridge can be classified as black shale-type deposits, geochemically and genetically comparable to e.g. Cretaceous black shales from lowlatitude settings. • Probably the closest modern analogues of this Arctic depositional setting are deep anoxic basins of the Baltic Sea (e.g. Gotland Deep). • The accumulation of organic matter was most probably supported by a combination of elevated primary productivity, and enhanced preservation under anoxic to euxinic bottom water conditions. • Even under these conditions, the Arctic Ocean was never a completely isolated ocean basin over the last ~60 million years, but had at least shallow connections to the world ocean and was episodically flushed with welloxygenated water masses. • The high biogenic opal productivity may have been significantly influenced by an increased delivery of bio-available iron that originated from rivers and/or suboxic shelf sediments. • The timing and cause of the termination of Arctic black shale deposition remains dubious, but our data strongly suggest that several periods of very low sedimentation or even sediment erosion between the middle Eocene and middle Miocene erased parts of the Cenozoic sediment record. • The first onset of modern-type, oxic conditions in the central Arctic are marked by extreme positive Ce anomalies, to our knowledge the highest ever reported from marine sediments.

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