Spatial Variation in Radar-Derived Basal Properties of Rutford Ice Stream, West Antarctica
Spatial Variation in Radar-Derived Basal Properties of Rutford Ice Stream, West Antarctica
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雷达衍生的南极洲西部拉特福德冰流基础特性的空间变化
DOI：
10.1002/essoar.10505715.1
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Schlegel R
中科院分区：
文献类型：
--
作者：
Schlegel R
众所周知，冰流和冰川下的基本性质是冰流动力学的控制因素，因此，由于冰川动力学的变化，对它们的了解对于预测海平面至关重要。基本性质、过程和地形也推动了冰下地貌的形成。以前在稀疏空间覆盖范围内使用地震声阻抗测量来描述拉特福德冰流(西南极洲)下的床层特性。在这里，我们从15×17公里的地面雷达数据网格中推导出地层属性，其覆盖范围和采样比以前的地震研究要高得多。利用由地震波阻抗得到的沉积物孔隙度(范围为0.4-0.5)标定了地表雷达数据中的地层反射幅度。研究发现，地层性质在空间上是可变的，有些地区由低孔隙度物质组成，有些地区由软质沉积物组成。地震和地面雷达资料的对比表明，低孔隙度物质为固结沉积或沉积岩。巨型冰川线理(MSGL)普遍存在于海床上，由软的、高孔隙度的、可能变形的沉积物组成，这与以前对MSGL的解释一致。我们发现，有些MSGL的顶部反射率高，被解释为覆盖在高孔隙度沉积物上的水体，而一些地貌周围的谷底和上游端则由低孔隙度物质组成。结合这些不同的观察，我们对地貌顶部出现水的可能解释施加了限制。
Basal properties beneath ice streams and glaciers are known to be a control for ice flow dynamics, hence knowledge of them is crucial for predicting sea level due to changes in glacial dynamics. Basal properties, processes and topography also drive the formation of subglacial landforms. Bed properties beneath Rutford Ice Stream (West Antarctica) have previously been described using seismic acoustic impedance measurements at a sparse spatial coverage. Here, we derive bed properties in a 15 x 17 km grid of surface radar data with coverage and sampling much higher than previous seismic studies. Bed reflection amplitudes in surface radar data were calibrated using sediment porosities (ranging from 0.4 – 0.5) derived from seismic acoustic impedance. We find the bed properties are spatially variable, consisting of low porosity material in some areas and soft sediment in other areas. Comparison of seismic and surface radar data imply the low porosity material to be a consolidated sediment or sedimentary rock. Mega-scale glacial lineations (MSGLs) are ubiquitous on the bed and consist of soft, high porosity, probably deforming sediment, consistent with previous interpretations of MSGLs. We find some MSGLs have high reflectivity on their crest, interpreted as water bodies overlying high porosity sediment, whereas the trough around and the upstream end of some landforms consist of low porosity material. Integrating these different observations, we place constraints on possible explanations for the occurrence of water on the crest of landforms.
南极冰下水文学：当前知识和未来挑战
影响因子：
1.6
作者：
D. Ashmore;R. Bingham
通讯作者：
R. Bingham