Variability in magnetic grain transported by the marine currents in the mid latitude South Indian Ocean and in the Mozambican channel during the interstadials
Abstract
Bulk magnetic parameters such as volume low field susceptibility (k), Anhysteretic Remanent magnetization (ARM) and Isothermal Remanent Magnetization (IRM) were measured in cores MD94103 and MD002375. These cores were taken by the french R.V vessel Marion Dufresne at mid south latitude locations in the Indian Ocean, during the PACIMA and ANTAUS cruises conducted in 1994 and 2000, respectively. In this sector of the South Indian ocean, magnetic grains are mainly magnetite, and they are transported by the Antarctic circum current (ACC) from the Crozet-Kerguelen plateau area to the sites of the studied cores. A strong variability in the amount of deposited magnetite characterizes interglacials MIS 5, 7, 9 and 11. ARM divided by k, a classical proxy for magnetite grain size, documents concomitant variations, with smallest magnetite grains associated to lowest levels of magnetite concentration. This suggests that the strength of the ACC has varied though time during these interstadials. Bulk magnetic parameters were also measured in core MD022584, taken in the Mozambican channel during the SWAFT-MOZAVITE cruise of the R.V. Marion- Dufresne in 2002. ARM divided by k signal of core MD022584 resembles that of cores MD94103 and MD002375. It suggests that current strength in the Mozambican channel and in the mid South Indian Ocean were closely connected during these interglacials. However, susceptibility signals differ in the two sectors. Implications for south Indian oceanic circulation will be discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMPP11A1360M
- Keywords:
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- 1512 Environmental magnetism;
- 1635 Oceans (1616;
- 3305;
- 4215;
- 4513);
- 4936 Interglacial;
- 4962 Thermohaline