Bailey, Ian; Foster, Gavin L.; Wilson, Paul A.; Jovane, Luigi; Storey, Craig D.; Trueman, Clive N.; Becker, Julia (2012): Flux and provenance of ice-rafted debris in the earliest Pleistocene sub-polar North Atlantic Ocean comparable to the last glacial maximum. Elsevier, Amsterdam, Netherlands, Earth and Planetary Science Letters, 341-344, 222-233, georefid:2013-013396
Abstract:
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 ( approximately 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-isotope composition ( (super 206) Pb/ (super 204) Pb, (super 207) Pb/ (super 204) Pb and (super 208) Pb/ (super 204) Pb) of individual ice-rafted (>150mu m) feldspars deposited at DSDP Site 611A, ODP Site 981 and IODP Site U1308 during MIS 100 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 MIS 100 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 ( approximately 23.8 ka) than that documented for MIS 5d ( approximately 106 ka). Comparison of our early Pleistocene and last glacial cycle datasets suggests that MIS 100 was characterised by abundant iceberg calving from large ice-sheets on multiple continents in the high northern latitudes (not just on Greenland). Abstract Copyright (2012) Elsevier, B.V.
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West: -30.1906 East: -14.3903 North: 55.2838 South: 49.5300
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