Interpretation of topography and bed properties beneath Thwaites Glacier, West Antarctica using seismic reflection methods
Interpretation of topography and bed properties beneath Thwaites Glacier, West Antarctica using seismic reflection methods
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DOI：
10.1016/j.epsl.2020.116543
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发表时间：
2020-11-15
影响因子：
5.3
通讯作者：
Voigt, Donald E.
中科院分区：
文献类型：
--
作者：
Clyne, Elisabeth R.;Anandakrishnan, Sridhar;Voigt, Donald E.
南极洲西部的思韦茨冰川（TG）在海洋强迫作用下正在损失质量。未来的演变可能导致南极西部冰原海洋盆地的消冰，这取决于当前和未来的气候强迫，但也取决于基础地形/水深测量、基础性质和在接地区内运行的物理过程。因此，了解TG内部和接地区的床型分布，并将其准确地纳入模型，以提高对撤退率和稳定性的估计是很重要的。在这里，我们通过对反射地震资料的振幅分析确定其声阻抗来估计床层的性质。我们报告了两条线的结果——纵向（l线）和横向（n线）——在离接地区内陆100公里的TG中央流线上。数据显示，地层形态和性质在空间上存在相当大的差异，这与内陆地区的类似调查结果相似。值得注意的是，我们在这里发现了同样的模式：硬（假定为基岩）材料在凸起的正面，软（假定为坡地）材料在背风面。物理认识表明，描述TG床层不同区域运动的基本流动规律可能从基岩区域的近粘性到基岩区域的近塑性变化，这为建模提供了指导。(C) 2020 Elsevier B.V.版权所有
Thwaites Glacier (TG), West Antarctica, is losing mass in response to oceanic forcing. Future evolution could lead to deglaciation of the marine basins of the West Antarctic Ice Sheet, depending on ongoing and future climate forcings, but also on basal topography/bathymetry, basal properties, and physical processes operating within the grounding zone. Hence, it is important to know the distribution of bed types of TG's interior and grounding zone, and to incorporate them accurately in models in order to improve estimates of retreat rates and stability. Here we estimate properties of the bed by determining its acoustic impedance from amplitude analysis of reflection seismic data. We report on the results from two lines - a longitudinal (L-Line) and a transverse (N-Line) - on a central flowline of TG similar to 100 km inland from the grounding zone. The data show considerable spatial variability in bed forms and properties, similar to results from a comparable survey farther inland. Notably, we find the same pattern here of hard (presumed bedrock) material on the stoss side of bumps and soft (presumed till) on the lee side. Physical understanding indicates the basal flow law describing motion over different regions of TG's bed likely varies from nearly-viscous over the bedrock regions to nearly-plastic over till regions, providing guidance for modeling. (C) 2020 Elsevier B.V. All rights reserved.