[论文解读] Applying Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) spectral indices for geological mapping and mineral identification on the Tibetan Plateau

Robert Corrie, Yoshiki Ninomiya+1 more|arXiv (Cornell University)|Jul 18, 2011

Geochemistry and Geologic Mapping参考文献 17被引用 11

一句话总结

本研究将ASTER热红外光谱指数应用于青藏高原西部-中部地区，以绘制岩性图并识别矿物，重点研究蛇绿混杂岩和缝合带岩石。该方法能有效区分石英质、碳酸盐质和硅酸盐质岩性，结果与现有地质图和野外数据高度吻合，证明了ASTER TIR数据在偏远、半干旱地区地质制图中的实用性。

ABSTRACT

The Tibetan Plateau holds clues to understanding the dynamics and mechanisms associated with continental growth. Part of the region is characterized by zones of ophiolitic melange believed to represent the remnants of ancient oceanic crust and underlying upper mantle emplaced during oceanic closures. However, due to the remoteness of the region and the inhospitable terrain many areas have not received detailed investigation. Increased spatial and spectral resolution of satellite sensors have made it possible to map in greater detail the mineralogy and lithology than in the past. Recent work by Yoshiki Ninomiya of the Geological Survey of Japan has pioneered the use of several spectral indices for the mapping of quartzose, carbonate, and silicate rocks using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) thermal infrared (TIR) data. In this study, ASTER TIR indices have been applied to a region in western-central Tibet for the purposes of assessing their effectiveness for differentiating ophiolites and other lithologies. The results agree well with existing geological maps and other published data. The study area was chosen due to its diverse range of rock types, including an ophiolitic melange, associated with the Bangong-Nujiang suture (BNS) that crops out on the northern shores of Lagkor Tso and Dong Tso ("Tso" is Tibetan for lake). The techniques highlighted in this paper could be applied to other geographical regions where similar geological questions need to be resolved. The results of this study aim to show the utility of ASTER TIR imagery for geological mapping in semi-arid and sparsely vegetated areas on the Tibetan Plateau.

研究动机与目标

• 评估ASTER热红外（TIR）光谱指数在偏远、高海拔地区地质制图中的有效性。
• 利用ASTER TIR数据识别并区分岩性，如蛇绿混杂岩、石英质岩、碳酸盐岩和硅酸盐岩。
• 评估光谱指数在探测与构造特征（如班公-怒江缝合带）相关的矿物成分变化方面的潜力。
• 为其他构造复杂、植被稀疏、野外访问受限的地区提供一种遥感制图方法。

提出的方法

• 应用由吉木义纪（Yoshiki Ninomiya）开发的ASTER热红外（TIR）数据光谱指数，以检测石英、碳酸盐和硅酸盐矿物。
• 利用ASTER在热红外波段（8.12–11.65 μm）的14个光谱带，推导出针对矿物的特定指数。
• 对ASTER TIR指数进行空间分析，以绘制青藏高原西部-中部地区岩性边界和矿物分布图。
• 将ASTER反演的矿物图与现有地质图及已发表的野外数据进行对比，以验证结果。
• 重点研究拉果错和东措附近班公-怒江缝合带区域，该区域出露蛇绿混杂岩。
• 采用图像处理技术增强光谱对比度，提高岩性判别能力。

实验结果

研究问题

• RQ1 ASTER TIR光谱指数能否在青藏高原有效区分蛇绿混杂岩与周围岩性？
• RQ2 ASTER反演的矿物图与现有地质图及野外观测相比，准确度如何？
• RQ3 在偏远、半干旱地形中，光谱指数在多大程度上可检测石英、碳酸盐和硅酸盐含量的变化？
• RQ4 ASTER TIR数据在构造复杂、难以进入的区域进行区域尺度地质制图方面具有多大潜力？

主要发现

• ASTER TIR光谱指数在青藏高原西部-中部地区成功区分了石英质、碳酸盐质和硅酸盐质丰富的岩性。
• 基于ASTER指数生成的矿物图与现有地质图及已发表的野外数据具有高度的空间一致性。
• 通过光谱指数，特别是对橄榄石和辉石敏感的指数，清晰地勾勒出与班公-怒江缝合带相关的蛇绿混杂岩。
• 该方法在半干旱、植被稀疏的地形中表现有效，因光谱对比度较高且大气干扰较小。
• 结果表明，ASTER TIR数据可在野外访问受限或不切实际的区域支持区域地质制图。