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中国典型斑岩铜矿遥感蚀变分带模型研究

The Study of Remote Sensing Alteration Zoning Model of Chinese Typical Porphyry Copper

【作者】 姚佛军

【导师】 毛景文; 杨建民; 张玉君;

【作者基本信息】 中国地质大学(北京) , 矿物学、岩石学、矿床学, 2012, 博士

【摘要】 斑岩铜矿是全球重要的矿床类型之一,其铜资源量占全球的50%以上。斑岩铜矿具有非常好的蚀变分带,利用遥感研究它的蚀变分带是一种有效的手段。论文从蚀变矿物的光谱特征入手,对电子跃迁产生的吸收和分子振动产生的吸收进行机理研究,研究了矿物物质成分、形成温度、分子键能与光谱吸收的关系,归纳总结了成矿热液对应的蚀变矿物在ASTER遥感数据各波段的吸收特征。并以此为基础,选择高寒山区的西藏多不杂斑岩铜矿矿集区、戈壁荒漠区的新疆土屋斑岩铜矿、植被覆盖区的江西德兴斑岩铜矿为代表,在成矿地质背景和矿床地质分析研究的基础上,建立了斑岩铜矿的遥感蚀变分带模型:岩浆热液期钾氢蚀变矿物晕在岩体和围岩形成蚀变矿物分带特征,即从岩体中心向外围围岩,岩浆热液温度逐步降低,形成的蚀变矿物温度也从中高温向中低温过渡,蚀变分带顺序为钾硅化带、绢英岩化带、泥化带和青磐岩化带,各蚀变分带蚀变矿物波谱特征具有显著区别,能够利用遥感技术进行提取,提取结果与实际蚀变分带情况对应关系非常好。本次研发出斑岩铜矿遥感蚀变分带信息提取的技术方法,包含了数据分析、信息提取和异常分类三大步骤,核心是信息提取,信息提取主要模型是比值法、斜率法、相关吸收深度法和主成分分析法,该模型的建立是在矿床岩矿石波谱测试分析的基础上进行的。论文从分子键振动和电子跃迁产生光谱吸收特征与元素丰度的关系入手,对多龙矿集区内地球化学采样数据进行分析,发现铜含量变化对ASTER光谱特征吸收有一定的影响。根据这个特征,利用铜元素的含量变化关系,通过四个特征指标相关比值、斜率指数、相关吸收深度指数和多项式指数的建立,利用多元回归分析,反演了区域内铜元素的地球化学特征,结果与1:5万实测地球化学结果相近似。论文根据雷达数据对构造识别明显的特点,对江西德兴斑岩铜矿、新疆土屋斑岩铜矿和西藏多不杂矿集区内断裂特征进行识别,识别效果比较好,雷达对分析矿田构造具有实用意义。最后论文通过对斑岩铜矿构造背景,岩浆岩特征、围岩特征、矿床构造特征、蚀变特征、元素分带特征、地球化学特征、地球物理特征的总结,并归纳了斑岩铜矿的蚀变分带模型、斑岩铜矿的遥感地球化学特征,斑岩铜矿雷达构造特征,遥感影像和岩性增强特征,建立了斑岩铜矿的遥感找矿模型,并在西藏多龙矿集区区域上进行了应用,共优选了7个靶区。

【Abstract】 The porphyry copper deposit is one of the important type of copper deposits of world. It’s copper resources acconted for more than 50% of the world’s copper. The porphyry copper deposit has a very good alteration zoning, which is used for study by remote sensing as an effective means. This paper studied the absorption mechanism of spectrum derived from the molecular vibrations or the electronic transition, which was the relationship of the mineral composition, the mineral formation temperature, the molecules key and the mineral spectral absorption, and summarized the alteration mineral absorption features of hydrothermal fluids in ASTER remote sensing data. Based on that, the Duolong porphyry copper ore concentratioin of Tibet of the alphine mountains, the Tuwu porphyry copper deposit of Xinjiang of the Gobi desert and the Dexing porphyry copper deposit of Jiangxi of the vegetation cover were studid as the typical deposits, to analyze and research their the mineralization geological background and mineral geological features, and the model of remote sensing alteration zoning of the porphyry copper deposits was built. In this model, the alteration zoning was formed due to the potassium hydrogen alteration halo of the magmatic hydrothermal fluids, which included potassium silicification, phyllic zone, mud zone and propylitic alteration zone from high-temperature to low-temperature of the magmatic hydrothermal fluids. It’s results extraction using the model was consistent with the actual alteration zoning. The extraction method is porphyry copper alteration zoning information extraction techniques developed in this paper, which contained the data analysis, the information extraction and anomalies classification. The information extraction was the core of that, in which the main models were the ratio method, the slope method, the absorption depth method and the principal component analysis, based on the test and analysis of the rock and mineral spectrum.In this paper, the relationship of the element abundances and the spectral absorption characteristics of the vibration of molecular bonds and the electronic transitioin was studied as foundation, then geochemical sampling data were analyzed. The ASTER remote sensing spectral bands absorption features was associated with the copper content, on which the geochemical inversion using multiple regression analysis of the ratio, the slope index, the aborption depth index and the polynomial index of remote sensing based. The results were similar with 1:50000 measured geochemical results.The faults features of Duolong porphyry copper ore concentratioin of Tibet, the Tuwu porphyry copper deposit of Xinjiang and the Dexing porphyry copper deposit of Jiangxi were identified according to the radar data significant features on the fracture. The results were very good. The analysis of the structures of ore field using radar data had practical significance.Finally, the remote sensing model was built based on the metallogenic tectonic background, the characteristics of the magmatic roks and the surrounding rocks, structural characterisitics, the alteration features, the elements zoning features, the geochemistry and geophysical characteristics, the remote sensing alteration zoning model, the remote sensing geochemical characteristics, the structural features of radar data, the remote sensing images and lithological enhancement characteristics of the porphyry copper deposits, which was applied in mineral prospecting on Duolong ore concentratioin of Tibet, the target were preferred.

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