【研究目的】 “图谱合一”的GF-5 AHSI国产卫星高光谱数据可以根据光谱精细特征进行蚀变矿物的直接识别，一次过境成像即可获取宽幅大面积高光谱数据，能够为陆域自然资源调查提供重要的数据支撑，本文开展了GF-5高光谱数据蚀变矿物提取、分析与验证研究，以期推动国产卫星高光谱数据在地质领域的深化应用。【研究方法】建立了GF-5高光谱数据预处理和蚀变矿物填图技术流程，在改进传统光谱角匹配算法基础上提出了一种整体谱形-吸收峰位协同的光谱匹配新方法，应用python语言开发了相应的算法模块，在甘肃省花牛山地区开展了矿物填图应用，综合分析了岩性-构造-蚀变多源地学要素，应用野外地质调查和ASD光谱测量方法对蚀变矿物提取结果进行了验证。【研究结果】应用GF-5高光谱数据成功提取了花牛山地区的9种蚀变矿物，分别为褐铁矿、赤铁矿、绿泥石、方解石、白云石、短波云母、中短波云母、中长波云母、长波云母，编制了整景3600 km2的蚀变矿物分布图。该地区定向分布的白云石和方解石矿物反映了碳酸盐成分的沉积/变质地层的地表出露情况，绿泥石矿物揭示了富含角闪石矿物地质体的分布，褐铁矿和赤铁矿矿物反映了与酸性花岗岩有关的热液活动，短波云母主要分布在二长花岗岩体内，中短波云母反映了中酸性岩体与敦煌岩群老地层接触带等特殊构造部位的热液活动，中长波云母与北东向断裂构造关系密切，长波云母暗示存在早石炭世之前的热液活动。【结论】 GF-5高光谱数据能够提取褐铁矿等9种蚀变矿物，结果证实蚀变矿物填图结果可信。不同蚀变矿物在地质涵义方面存在较大差异，碳酸盐矿物与沉积/变质地层关系密切，云母矿物更多反映了与中酸性岩体及断裂构造有关的热液活动。本文认为GF-5高光谱数据可有效服务于地质体快速识别和界线修编、新鲜样品采样定位等自然资源领域基础地质调查和矿产地质勘查工作。
This paper is the result of mineral exploration engineering.
[Objective]The GF-5 AHSI satellite hyperspectral data, featured by the integration of both image and spectrum, can be utilized to directly identify alteration minerals according to their fine spectral characteristics. Large-area wide-range hyperspectral data can be easily obtained by one transit imaging, which can well support the survey of land natural resources. This work extracted alteration minerals using the GF-5 hyperspectral data, and conducted further analysis and field verification, in an attempt to promote the deepening application of China's satellite hyperspectral data in geological field.[Methods]Technical workflows of preprocessing GF-5 hyperspectral data and alteration mineral mapping were established. Based on the improvement of the traditional spectral angle matching algorithm, a new spectral matching method of the whole spectral shape synergy with absorption peak position was proposed, and the corresponding algorithm module with the Python language was developed. Taking the Huaniushan area of Gansu Province as an example, we conducted mineral mapping, and comprehensively analyzed multi-source geological elements including lithology, structure, and alteration. The extracted alteration minerals were then verified by field survey and ASD spectral measurements.[Results]Nine types of alteration minerals were successfully extracted using the GF-5 hyperspectral data, i.e., limonite, hematite, chlorite, calcite, dolomite, short-wave sericite, medium-to short-wave sericite, medium-to long-wave sericite and long-wave sericite, to describe the distribution of alteration minerals with an area of 3600 km2. The directionally distributed dolomite and calcite minerals reflect the surface exposure of sedimentary or metamorphic strata with carbonate composition. Chlorite minerals reveal the distribution of geological bodies rich in amphibole. Limonite and hematite minerals are indicative of the hydrothermal activities related to acid granites. Short-wave sericite was mainly distributed in the monzogranite. Medium-to short-wave sericite is suggestive of the hydrothermal activity of special structural section such as the contact zone between intermediate and acid rock masses and the old Dunhuang Complex. Medium-to long-wave sericite was closely related to the NE-trending fault. Long-wave sericite indicates the presence of hydrothermal activity before the Early Carboniferous.[Conclusions]The GF-5 hyperspectral data can extract nine types of alteration minerals including limonite, and the field verification confirms the reliability of alteration mineral mapping. Different alteration minerals may be interpreted from varying aspects. Carbonate minerals are inferred to be closely related to sedimentary or metamorphic strata, while sericite minerals mostly reflect hydrothermal activities related to intermediate to acid rock mass and fault structure. It is considered that the GF-5 hyperspectral data can rapidly identify geological bodies, and can help to revise geological boundary and locate fresh samples, which will effectively serve the basic geological survey and mineral geological exploration in the field of natural resources.
孙雨,刘家军,赵英俊,翟德高,柳振江,张亚峰,张方方,田丰,秦凯. 基于GF-5高光谱数据的蚀变矿物填图及地质应用——以甘肃省瓜州县花牛山地区为例[J]. 中国地质, 2022, 49(2): 558-574.
SUN Yu, LIU Jiajun, ZHAO Yingjun, ZHAI Degao, LIU Zhenjiang, ZHANG Yafeng, ZHANG Fangfang, TIAN Feng, QIN Kai. Alteration mineral mapping based on the GF-5 hyperspectral data and its geological application——An example of the Huaniushan area in Guazhou County of Gansu Province[J]. Geology in China, 2022, 49(2): 558-574(in Chinese with English abstract).