Pliocene deglacial event timelines and the biogeochemical response offshore Wilkes Subglacial Basin, East Antarctica
Pliocene deglacial event timelines and the biogeochemical response offshore Wilkes Subglacial Basin, East Antarctica
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DOI：
10.1016/j.epsl.2018.04.054
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发表时间：
2018-07-15
影响因子：
5.3
通讯作者：
Riesselman, Christina R.
中科院分区：
文献类型：
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作者：
Bertram, Rachel A.;Wilson, David J.;Riesselman, Christina R.
在比现在更温暖的上新世期间，格陵兰岛和西南极洲的冰盖显着减少，这可能是全球平均海平面上升约 10 米的原因。任何超出此范围的海平面上升都需要东南极冰盖（EAIS）的贡献。先前的研究已经提供了来自地质记录的低分辨率地球化学证据，表明在 EAIS 的低洼地区（例如威尔克斯冰下盆地），冰层反复进退。然而，撤退事件的发生率和机制受到的限制较少。在这里，我们展示了威尔克斯冰下盆地近海 IODP 站点 U1361A 上新世中后期三个时间间隔内的轨道分辨海洋碎屑沉积物来源数据，以及冰筏碎片和生产力代理数据。我们的新数据表明，上新世沉积物来源的变化与海洋生产力的增加同时发生，而这种变化的开始以冰筏碎片质量积累率的峰值为标志。沉积物来源和海洋生产力变化的一致性反对冰流之间沉积物输送的转变，相反表明冰消变暖引发了冰山崩解率的增加，随后冰缘向内陆退缩。威尔克斯冰下盆地内从冰川消退开始到内陆冰缘退缩的时间尺度约为数千年。这一地质证据证实了冰盖模型确定的退缩率，以及上新世中晚期间冰期期间东南极冰盖最脆弱地区之一等效海平面上升约 3 至 4 m 的贡献。 (C) 2018 作者。由 Elsevier B.V. 出版
Significantly reduced ice coverage in Greenland and West Antarctica during the warmer-than-present Pliocene could account for similar to 10 m of global mean sea level rise. Any sea level increase beyond this would require contributions from the East Antarctic Ice Sheet (EAIS). Previous studies have presented low-resolution geochemical evidence from the geological record, suggesting repeated ice advance and retreat in low-lying areas of the EAIS such as the Wilkes Subglacial Basin. However, the rates and mechanisms of retreat events are less well constrained. Here we present orbitally-resolved marine detrital sediment provenance data, paired with ice-rafted debris and productivity proxies, during three time intervals from the middle to late Pliocene at IODP Site U1361A, offshore of the Wilkes Subglacial Basin. Our new data reveal that Pliocene shifts in sediment provenance were paralleled by increases in marine productivity, while the onset of such changes was marked by peaks in ice-rafted debris mass accumulation rates. The coincidence of sediment provenance and marine productivity change argues against a switch in sediment delivery between ice streams, and instead suggests that deglacial warming triggered increased rates of iceberg calving, followed by inland retreat of the ice margin. Timescales from the onset of deglaciation to an inland retreated ice margin within the Wilkes Subglacial Basin are on the order of several thousand years. This geological evidence corroborates retreat rates determined from ice sheet modeling, and a contribution of similar to 3 to 4 m of equivalent sea level rise from one of the most vulnerable areas of the East Antarctic Ice Sheet during interglacial intervals throughout the middle to late Pliocene. (C) 2018 The Authors. Published by Elsevier B.V.