西藏马攸木地区多源遥感蚀变信息提取及找矿预测

    The extraction of alteration information from multi-source remote sensing data and mineral prospecting prediction in the Mayum area, Xizang

    • 摘要:
      研究目的 随着国内外地球观测技术的不断进步,遥感技术已逐渐成为地质调查和矿产资源勘查的重要手段。西藏作为国家新一轮找矿突破战略行动的关键地区,因地表植被覆盖度低等特征,为遥感识别与提取蚀变异常信息提供了条件。基于此,以西藏马攸木地区为研究对象,开展多源遥感蚀变信息提取与综合找矿预测研究。
      研究方法 利用 Landsat-8、Sentinel-2 多光谱数据与 GF-5 高光谱数据,采用主成分分析、波段比值、混合调制匹配滤波(MTMF)等方法提取遥感蚀变异常信息,并与结合 ILR 变换与稳健主成分分析(RPCA)处理的 1∶20 万化探数据进行综合分析,同时辅以野外调查验证。
      研究结果 结果表明:①Landsat-8、Sentinel-2 多光谱数据提取的蚀变异常在空间上具有良好的一致性,高异常区主要集中于研究区中部,表现为大面积团块状铁染与羟基异常;②GF-5 高光谱数据识别出多种类型的蚀变异常信息,与多光谱提取结果相互印证;③遥感蚀变异常与以 Hg、Sb、As 为主的1∶20 万地球化学负载荷异常具有较高的空间耦合性,据此在已知矿(化)点外围圈定出多处找矿远景区;④野外查证发现磁铁矿化、孔雀石化、绿帘石化等蚀变现象,验证了遥感异常的可靠性。
      结论 上述结果进一步证实了遥感提取方法的准确性,也为研究区下一步矿产勘查工作提供了查证方向和技术支撑。

       

      Abstract:
      Objective In recent years, with the rapid advancement of Earth observation technologies, remote sensing has become an essential tool in geological surveying and mineral exploration. Xizang, as a key region in China’s new round of strategic mineral exploration initiatives, is characterized by low vegetation coverage and favorable surface exposure conditions, which provide advantageous settings for the identification and extraction of alteration anomalies. Therefore, this study focuses on the Mayum area in Xizang to conduct multi−source remote sensing−based alteration extraction and integrated mineral prospectivity prediction.
      Methods Multispectral data from Landsat−8 and Sentinel−2, together with GF−5 hyperspectral data, were utilized to extract alteration anomalies using principal component analysis (PCA), band ratio techniques, and mixture tuned matched filtering (MTMF). Meanwhile, 1∶200000−scale geochemical data were processed using isometric log−ratio (ILR) transformation and robust principal component analysis (RPCA), followed by integrated analysis with remote sensing results. Field investigations were conducted for validation.
      Results The results indicate that: ① alteration anomalies extracted from Landsat−8 and Sentinel−2 data exhibit strong spatial consistency, with high−intensity anomalies mainly concentrated in the central part of the study area, characterized by extensive iron−staining and hydroxyl alteration zones; ② GF−5 hyperspectral data identified multiple types of alteration information, showing good agreement with multispectral results; ③ remote sensing−derived alteration anomalies demonstrate a strong spatial coupling relationship with geochemical loadings dominated by Hg, Sb, and As, based on which several prospective targets were delineated around known mineralized occurrences; ④ field verification confirmed the presence of magnetitization, malachitization, and epidotization, supporting the reliability of the remote sensing interpretation.
      Conclusions The results demonstrate that the proposed multi−source remote sensing approach is effective in extracting alteration information and delineating mineralization−favorable zones, confirming its applicability and reliability for mineral prospectivity prediction in the study area.

       

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