Ice rafte debris of ODP Hole 178-1101A

Sediment drifts on the continental rise west of the Antarctic Peninsula received fine-grained sediment and ice-rafted debris (IRD) directly from the continental shelf and thus indirectly record the history of West Antarctic glaciation. Site 1101 contains a 218-m-thick, nearly continuous section extending from the late Pliocene to the Holocene. To assess the presence of calving glaciers at sea level in the Antarctic Peninsula region, the mass accumulation rate (MAR) of IRD was calculated using the weight percent terrigenous sand fraction (250 µm to 2 mm). IRD MAR is cyclic throughout, with small peaks alternating with periods of low or no IRD. Many cycles have a sawtooth pattern that increases gradually to the peak then abruptly decreases to zero. This pattern is consistent with rapid disintegration of ice streams and release of icebergs from the continental shelf. Three unusually large peaks (three to five times the size of other peaks) occurred at approximately 2.8, 1.9, and 0.88 Ma and indicate periods of intense ice rafting. […]

南极半岛西侧大陆隆上的沉积物漂移体直接接收源自大陆架的细粒沉积物与冰筏碎屑（ice-rafted debris, IRD），进而间接记录了西南极冰川作用的演化历史。1101站位拥有一套厚度达218米、近乎连续的地层剖面，其沉积年代范围覆盖上新世晚期至全新世。为评估南极半岛区域海平面处是否存在崩解冰川，研究人员通过陆源砂组分（粒径250 μm至2 mm）的重量占比，计算得到冰筏碎屑的质量累积速率（mass accumulation rate, MAR）。冰筏碎屑的质量累积速率整体呈现周期性变化，峰值时段与低值或无碎屑的时段交替出现。多数周期呈现锯齿状形态：沉积物累积量逐步攀升至峰值后，骤然回落至零。该特征与冰流快速解体、大陆架释放冰山的过程高度吻合。在约2.8 Ma、1.9 Ma及0.88 Ma时出现三次异常巨大的峰值（规模为其他峰值的3至5倍），对应冰筏作用强烈的时期。[…]