Review article: Existing and potential evidence for Holocene grounding-line retreat and readvance in Antarctica
Review article: Existing and potential evidence for Holocene grounding-line retreat and readvance in Antarctica
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DOI：
10.5194/tc-2021-360
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发表时间：
2021-12
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通讯作者：
Joanne S. Johnson;R. Venturelli;G. Balco;C. Allen;S. Braddock;S. Campbell;B. Goehring;B. Hall;P. Neff;K. Nichols;D. Rood;E. Thomas;J. Woodward
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作者：
Joanne S. Johnson;R. Venturelli;G. Balco;C. Allen;S. Braddock;S. Campbell;B. Goehring;B. Hall;P. Neff;K. Nichols;D. Rood;E. Thomas;J. Woodward
抽象的。现代冰盖表面以上和当前冰缘外侧的广泛现有地质记录表明，南极冰盖（AIS）在末次冰盛期（~20 ka）比现在更广泛。然而，在过去的几千年里，它是否比现在更小，以及（如果是的话）缩小了多少，目前只知道少数几个地点，因为直接证据位于冰盖内部或下方，很难进入。在这里，我们描述了如何后退和readvance（以下简称“readvance”）AIS接地线在全新世可以检测和量化使用冰下基岩，冰下沉积物，海洋沉积物岩心，相对海平面（RSL）记录，雷达数据，和冰芯。其中，只有冰下基岩和冰下沉积物可以提供直接的证据。海洋档案的用处有限，因为再前进通常包括早期撤退的证据。然而，记录环境变化的地层过渡可能为冰下记录的直接证据提供支持，RSL记录中存在海侵也是如此。通过独立的年龄控制，雷达揭示的冰结构和流动模式的过去变化可以用来推断冰量的变化与前浪相称。由于冰芯捕捉到了地表物质平衡、海拔高度以及大气和海洋环流的变化，这些变化已知会驱动地面线迁移，因此它们也有可能用于识别再流动。一个多学科的方法可能会提供最有力的证据支持或反对一个小于目前的AIS在全新世。
Abstract. Widespread existing geological records from above the modern ice-sheet surface and outboard of the current ice margin show that the Antarctic Ice Sheet (AIS) was much more extensive at the Last Glacial Maximum (~20 ka) than at present. However, whether it was ever smaller than present during the last few millennia, and (if so) by how much, is known only for a few locations because direct evidence lies within or beneath the ice sheet, which is challenging to access. Here, we describe how retreat and readvance (henceforth “readvance”) of AIS grounding lines during the Holocene could be detected and quantified using subglacial bedrock, subglacial sediments, marine sediment cores, relative sea-level (RSL) records, radar data, and ice cores. Of these, only subglacial bedrock and subglacial sediments can provide direct evidence for readvance. Marine archives are of limited utility because readvance commonly covers evidence of earlier retreat. Nevertheless, stratigraphic transitions documenting change in environment may provide support for direct evidence from subglacial records, as can the presence of transgressions in RSL records. With independent age control, past changes in ice structure and flow patterns revealed by radar can be used to infer ice volume changes commensurate with readvance. Since ice cores capture changes in surface mass balance, elevation, and changes in atmospheric and oceanic circulation that are known to drive grounding-line migration, they also have potential for identifying readvance. A multidisciplinary approach is likely to provide the strongest evidence for or against a smaller-than-present AIS in the Holocene.