Glacial History of the Amundsen Sea Shelf

该奖项由极地计划办公室南极地质和地球物理计划提供，支持对阿蒙森海地区进行海洋地质调查，以更好地了解南极西部冰盖（WAIS）的冰川消退历史。WAIS可能天生不稳定，因为它是世界上最后一个海洋冰盖。与南极洲西部的其他海湾不同，从WAIS内部流入阿蒙森海的主要冰流缺乏支撑冰架。这些冰流（松岛和思韦茨冰川）的远端部分的质量平衡数据似乎处于平衡状态，或者可能变得负值。由于这两条冰流都有向冰盖中心向下倾斜的河床，无论是持续变薄还是海平面上升导致的地面线退缩都可能引发不可逆转的地面线退缩，导致冰盖解体和随之而来的全球海平面上升。阿蒙森海有限的海洋地质和地球物理数据表明，直到1000至2000年前，接地冰或冰架才占据了阿蒙森海内湾，并且这些冰可能在历史上迅速消退。该项目是对阿蒙森海大陆架西经100度至西经130度的海洋地质和地球物理的研究，该项目旨在解决WAIS科学计划优先目标H2的阿蒙森海部分：“罗斯东部、别林斯高晋海和阿蒙森海的冰川消退历史是什么？“该项目将检查阿蒙森海大陆架的测深数据，以确定以前冰-蒸汽通道的位置，并协助选择沉积物取芯地点。将进行单道地震反射研究，以确定沉积物厚度模式，帮助选择取芯地点，并定位和确定表明以前的地面冰的形态特征（例如，冰碛、冲刷、凹槽、条纹、冰碛楔和三角洲等）。取芯将集中在沿着以前的冰流线上。将在实验室中对岩芯样品进行沉积学分析，以确定是否存在基底冰碛（表明以前的冰及其以前的范围），以及钙质和硅质微体化石。将利用加速器质谱（AMS）的酸不溶性微粒有机碳碳-14测年法确定冰架断裂附近假定的末次冰盛期位置的基线和冰架后退的年代。收集的海洋地质数据和样本将与其他调查人员的调查结果相结合，以全面解释WAIS的历史。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a marine geological investigation of the Amundsen Sea region toward a better understanding of the deglaciation history of the West Antarctic Ice Sheet (WAIS). The WAIS may be inherently unstable because it is the last marine-based ice sheet in the world. Unlike other embayments in West Antarctica, major ice streams draining into the Amundsen Sea from the interior of the WAIS lack buttressing ice shelves. Mass balance data for the distal portions of these ice streams (Pine Island and Thwaites glaciers) appear to be in balance or may be becoming negative. Because both ice streams have beds that slope downward toward the center of the ice sheet, grounding-line recession resulting from either continued thinning or sea-level rise could trigger irreversible grounding-line retreat, leading to ice-sheet disintegration and consequent global sea-level rise. The limited marine geological and geophysical data available from the Amundsen Sea suggest that grounded ice or an ice shelf occupied the inner Amundsen Sea embayment until perhaps as recently as 1000 to 2000 years ago, and this ice may have retreated rapidly in historic time.This project, a study of the marine geology and geophysics of the Amundsen Sea continental shelf from 100 degrees W to 130 degrees W, is designed to address the Amundsen Sea part of WAIS Science Plan Priority Goal H2: "What is the deglaciation history in the eastern Ross, the Bellingshausen and Amundsen Seas?" This project will examine bathymetric data of the Amundsen Sea continental shelf to determine the positions of former ice-steam channels, and to aid in choosing sites for sediment coring. Single-channel seismic reflection studies will be conducted in order to determine sediment-thickness patterns, to aid in choice of coring sites, and to locate and identify morphologic features indicative of former grounded ice (e.g., moraines, scours, flutes, striations, till wedges and deltas, etc.). Coring will be concentrated along former ice flow-lines. Core samples will be analyzed in the laboratory for sedimentology, to determine whether of not basal tills are present (indicating former grounded ice and its former extent), and for calcareous and siliceous microfossils. The chronology of grounding-line and ice-shelf retreat from a presumed Last Glacial Maximum position near the shelf break will be established using accelerator mass spectrometry (AMS) carbon-14 dates of acid-insoluble particulate organic carbon.This project will share ship time in the Amundsen Sea with a physical oceanographic project. Marine geologic data and samples collected will be integrated with findings of other investigators toward developing a comprehensive interpretation of the history of the WAIS.