Artículos de revistas
Flux and provenance of ice-rafted debris in the earliest Pleistocene sub-polar North Atlantic Ocean comparable to the last glacial maximum
Fecha
2012-07-13Registro en:
Earth and Planetary Science Letters, v. 341-344 , 2012
10.1016/j.epsl.2012.05.034
Autor
Bailey, Ian
Foster, Gavin L.
Wilson, Paul A.
Jovane, Luigi
Storey, Craig D
Trueman, Clive N.
Becker, Julia
Institución
Resumen
Relatively little is known in detail about the locations of the early Pleistocene ice-sheets responsible for ice-rafted debris(IRD) inputs to the sub-polar North Atlantic Ocean during intensification of northern hemisphere glaciation (iNHG). To shed new light on this problem,we present the first combined in-depth analysis of IRD flux and geochemical provenance of individual sand-sized IRD deposited in the sub-polar North Atlantic Ocean during the earliest large amplitude Pleistocene glacial, marine isotope stage (MIS)100( 2.52 Ma),arguably the key glacial during iNHG. IRD provenance is assessed using laser ablation lead (Pb) isotope analyses of single feldspar grains. We find that the Pb-isotopecomposition (206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) of individual ice-rafted (4150 mm)feldspars deposited at DSDP Site 611A, ODP Site 981 and IODP Site U1308 during MIS100 records a shift from predominantly Archaean-aged circum-North Atlantic Ocean continental sources during early glacial ice-rafting events to dominantly Palaeozoic and Proterozoic-aged sources during full glacial conditions. The distribution of feldspars in Pb–Pb space for full glacial MIS100 more closely resembles that documented for feldspars deposited at the centre of the last glacial IRD belt (at IODP/DSDP Site U1308/609) during ambient (non-Heinrich-event) ice-rafting episodes of MIS 2 ( 23.8 ka) than that documented for MIS 5d ( 106 Ka). Comparison of our early Pleistocene and last glacial cycle datasets suggests that MIS100 was characterised by abundant iceberg calving from large ice-sheets on multiplecontinents in the high northern latitudes (notjustonGreenland).