Trace element signatures of Peruvian and Chilean upwelling sediments

The continental margin off Peru and Chile is characterized by very high organic matter (OM) flux modulating the water column/sedimentary redox state significantly and having an impact on the global carbon cycle. Bulk sediment redox/bio-sensitive trace elements - promising tracers for (paleo) environmental reconstructions - were studied with respect to the influence of surface water productivity, early diagenetic OM remineralisation, sulfate reduction and pyrite formation. The context between the specific trace element availability in sea water, the accumulation of specific trace elements in biodetritus and the recording of these signals in Peruvian sediments could be clearly demonstrated. An overwhelming fraction of Mn and Co is already remobilized from particles settling through the Peruvian oxygen minimum zone (OMZ) implying a strongly reducing but non-sulfidic watercolumn. The sulfidic conditions within OMZ sediments are indicated by the extreme enrichments of e.g. Cd, Mo and Re. The suboxic conditions for sediments below the OMZ are indicated by moderate Cd, Mo contents but high Re contents. Cadmium, Cu, Zn, Ni, Cr, Ag, and Tl predominantly accumulate via biogenic pre-concentration in plankton remains whereas Re, Sb, As, V, U and Mo are enriched in accordance with seawater trace element availability. Off central Chile, the OMZ is smaller and weaker with implications for the trace element signature. Despite of lower accumulation of trace elements the enrichment mechanisms must be similar to those off Peru. A comparison of global upwelling sediment chemistries yields that two types of upwelling sediments are discernable due to their different degree in trace element accumulation.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Oldenburg

Year

2004

Author dc:creator

• Böning, Philipp

• [Keine Schlagwörter von Autor/in vergeben.]

Repository record source_url

http://oops.uni-oldenburg.de/116

OAI identifier oai:identifier

oai:oops.uni-oldenburg.de:116