A combined geochemical and rock-magnetic investigation of a redox horizon at the last glacial/interglacial transition

作者：Reitz A^*; Hensen C; Kasten S; Funk JA; de Lange GJ

来源：Physics and Chemistry of the Earth, 2004, 29(13-14): 921-931.

DOI：10.1016/j.pce.2004.03.013

• equatorial Atlantic Ocean
• high resolution investigation
• geochemistry
• rock-magnetics
• non-steady-state diagenesis
• Fe (2+)/Fe (3+) redoxboundary

A high-resolution study of an active Fe2+/Fe3+ redox horizon has been carried out on sediments of the central equatorial Atlantic. The multidisciplinary approach combining geochemical and rock-magnetic parameters gives evidence of the interrelation of the redox horizon with the last change from glacial to interglacial conditions (T1). Distinct enrichments of redox-sensitive elements (Mn, Fe, V, and U) reveal a characteristic depth-sequence, indicating non-steady-state diagenetic conditions caused by a decrease in productivity and an increase in oxygen content in the bottom water during T1 and a reversal during the Holocene. Thus, the redox boundaries first moved down into the sediment and subsequently upwards. The movement of the redox boundaries led to the development of conspicuous double peaks for Fe and Mn. The reconstruction based on geochemical data is supported by susceptibility and magnetization measurements of the sediments displaying well-defined anomalies in the vicinity of active and paleo redox boundaries. The combination of geochemical and rock-magnetic parameters, like the ferrimagnetic susceptibility, and total Fe concentration (chi(f)/Fe) are suitable for characterizing distinct zones of dissolution and precipitation of ferromagnetic mineral phases (e.g. magnetite). Moreo

• 出版日期2004