Ice shelf history from petrographic and foraminiferal evidence, northeast Antarctic Peninsula

first_imgA detailed record of late Pleistocene deglaciation followed by mid-Holocene ice shelf breakup and late Holocene re-growth iscontained in continental shelf sediments in the northern Larsen area, northeast Antarctic Peninsula. The zero age of core tops isconfirmed by new and published 210Pb profiles, and 70 accelerator mass spectrometer (AMS) 14C dates on bulk organic carbon definesedimentation rates of 7.6–92 cm/ka. The varied geology in the local ice drainage basins facilitates the use of ice-rafted debris (IRD)provenance in determining the presence or absence of ice shelves. All inshore cores contain an interval of non-local IRD in the postglacialsection, demonstrating widespread ice shelf breakup in the mid-Holocene. Both breakup and re-growth may have taken centuriesand there are no widespread debris layers associated with breakup. Cores beyond and up to 30km inside the historical ice shelf limitexhibit a varied IRD provenance throughout the Holocene, suggesting the maximum ice shelf limit may date only from the Little Ice Age.Benthic foraminiferal assemblages are related to water masses and position on the continental shelf and have been modified bytaphonomic processes. Nevertheless we discern a deglaciation signal in Prince Gustav Channel of a calcareous spike in predominantlyagglutinated assemblages, and this is repeated at the time of mid-Holocene ice shelf breakup. The inferred mid-Holocene warm periodoccurred later in the northern Larsen area than on the west coast of the Antarctic Peninsula.last_img

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