Publication Date

April 2016


Suzanne O'Connell


Earth and Environmental Sciences


English (United States)


The Pliocene epoch (5.33-2.58 mya) is frequently studied in paleoclimatology because its climate conditions are similar to present and near future scenarios (Federov et al., 2013). Characterizing the stability of the Antarctic ice sheet during the Pliocene is therefore essential for building models on polar ice-sheet & Global Mean Sea Level (GMSL) response to warmer temperatures. Here, we present a sediment record spanning ~3-3.8 mya from Ocean Discovery Program (ODP) Site 697 in the Weddell Sea. Ice rafted debris (IRD) provenance and accumulation is analyzed to track potential stability changes in both the West and East Antarctic ice sheets. Site 697 shows large pulses in IRD accumulation in conjunction with peaks in surface ocean productivity from 3.3-3.6 mya, followed by a low IRD accumulation period from 3-3.3 mya. Mineral assemblages and 40Ar/39Ar dating of ice-rafted hornblendes/biotites links a large IRD component to bedrock eroded from Coats Land (East Antarctica) and subsequent calving from the Filchner Ice Shelf. Icebergs from this source probably traveled a large distance in a Weddell gyre before reaching Site 697, indicating that IRD pulses are of a large magnitude. If these ice-rafting events are originating from fringing ice shelves during Pliocene warmth, it could have large implications for ice sheet stability, highlighting the Weddell Sea embayment as an area of dynamic change



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