Water masses and depositional environments over the last 500 ka were reconstructed using absolute and relativeabundances of lithogenous, biogenous and redox-sensitive elements in four sediment cores from two channelleveesystems of the Wilkes Land continental slope (East Antarctica). Sediments older than the Mid-Bruhnesevent (MBE, 430 ka BP) show reduced glacial/interglacial variability in the abundance of elements associated tothe terrigenous mineral phases (i.e. Al, Ti, Fe and partly Si). This suggests minor ice-sheet size changes occurredin the Antarctic margin during the pre-MBE “lukewarm” interval. Post-MBE sediments record instead a highvariability between glacial and interglacial periods in the concentration of terrigenous and biogenous (i.e. Ca,Ba) elements suggesting larger amplitude changes in both ice-sheet size and ocean conditions toward the gradualestablishment of last glacial cycle conditions. Moreover, a marked increase of Mn during the glacial to interglacialtransitions, indicates a post-depositional migration of the redox front and re-oxidation of the surfacesediment layers linked to major changes in bottom water oxygen conditions associated to Antarctic BottomWater formation along the margin at the onset of deglaciations.

Late Pleistocene oceanographic and depositional variations along the Wilkes Land margin (East Antarctica) reconstructed with geochemical proxies in deep-sea sediments

Lucchi R;Caburlotto A;De Santis L
2020

Abstract

Water masses and depositional environments over the last 500 ka were reconstructed using absolute and relativeabundances of lithogenous, biogenous and redox-sensitive elements in four sediment cores from two channelleveesystems of the Wilkes Land continental slope (East Antarctica). Sediments older than the Mid-Bruhnesevent (MBE, 430 ka BP) show reduced glacial/interglacial variability in the abundance of elements associated tothe terrigenous mineral phases (i.e. Al, Ti, Fe and partly Si). This suggests minor ice-sheet size changes occurredin the Antarctic margin during the pre-MBE “lukewarm” interval. Post-MBE sediments record instead a highvariability between glacial and interglacial periods in the concentration of terrigenous and biogenous (i.e. Ca,Ba) elements suggesting larger amplitude changes in both ice-sheet size and ocean conditions toward the gradualestablishment of last glacial cycle conditions. Moreover, a marked increase of Mn during the glacial to interglacialtransitions, indicates a post-depositional migration of the redox front and re-oxidation of the surfacesediment layers linked to major changes in bottom water oxygen conditions associated to Antarctic BottomWater formation along the margin at the onset of deglaciations.
Wilkes Land; glaciation; Antarctic Bottom Water
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.14083/2947
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