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首页> 外文期刊>Antarctic science >Sedimentology of lower Pliocene to Upper Pleistocene diamictons from IODP Site U1358, Wilkes Land margin, and implications for East Antarctic Ice Sheet dynamics
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Sedimentology of lower Pliocene to Upper Pleistocene diamictons from IODP Site U1358, Wilkes Land margin, and implications for East Antarctic Ice Sheet dynamics

机译：IODP站点U1358，威尔克斯土地边缘的下新世至上更新世双生子的沉积学及其对南极东部冰盖动力学的影响

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摘要

During the early Pliocene a dynamic marine-based ice sheet retreated from the Wilkes Land margin with periodic ice advances beyond Last Glacial Maximum position. A change in sand provenance is indicative of a more stable Mertz Glacier system during the Late Pleistocene. East Antarctic Ice Sheet (EAIS) dynamics were evaluated through the analysis of marine diamictons from Integrated Ocean Drilling Program (IODP) site U1358 on the Adélie Land continental shelf. The warmer than present conditions of the early Pliocene coupled with the site's proximity to the landward sloping Wilkes Subglacial Basin provided the rationale for the investigations at this site. Based on visual core descriptions, particle size distributions, and major and trace element ratios, we interpret the origin of lower Pliocene strata by intermittent glaciomarine sedimentation with open-marine conditions and extensive glacial advances to the outer shelf. Heavy mineral analyses show that sand-sized detritus in the lower Pliocene strata was sourced from local intermediate to high-grade metamorphic rocks near Mertz Glacier. In contrast, Pleistocene diamictons exhibit a larger contribution from a prehnite-pumpellyite greenschist facies suggesting supply via iceberg rafting from northern Victoria Land. From this sedimentological evidence, we postulate a shift from a dynamic EAIS margin in the early Pliocene to possible stabilization in the Pleistocene.
机译：在上新世早期，一个动态的基于海洋的冰盖从威尔克斯陆地边缘退缩，并且周期性的冰超前超过了最后冰川最大的位置。沙源的变化表明晚更新世期间更稳定的梅尔茨冰川系统。通过分析来自AdélieLand大陆架上的综合海洋钻探计划（IODP）站点U1358的海洋双曲子，评估了南极东部冰盖（EAIS）的动力学。上新世初期的天气比现在温暖，再加上该地点靠近陆坡倾斜的威尔克斯次冰川盆地，为该地点的调查提供了依据。基于视觉核心描述，粒度分布以及主要元素和微量元素比率，我们通过间歇性冰川海洋沉积和开放海洋条件以及广泛的冰川向外层架推进来解释上新世地层的成因。大量矿物分析表明，上新世下部地层的沙粒碎屑来自于梅尔茨冰川附近的局部中级至高级变质岩。相比之下，更新世的铁硅土表现出较大的绿橄榄石-粉晶铝石绿岩相，表明通过维多利亚州北部的冰山漂流来供应。从这一沉积学证据中，我们假设从上新世早期的动态EAIS边缘向更新世可能的稳定过渡。

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