基于RS技术的西藏甲玛铜多金属矿外围成矿预测研究

A study of the metallogenic prognosis for the periphery of Jiama copper-polymetallic ore,Tibet based on the RS method

甲玛铜多金属矿经过一年的勘探工作,发现矿区外围工业矿体仍未圈闭,其找矿潜力巨大。为了验证在周边区域存在矿化的可能性,笔者运用遥感技术对矿区及其周边区域进行成矿预测研究,力图能为甲玛的进一步勘查提供依据。文中运用ETM+图像进行主成分分析、比值分析、MNF变换,通过蒙赛尔变换,形成HLS图像,根据Fe3+、Si、OH-在解译图像中显示出高亮度反射的特点,设定阈值,从而提取遥感矿化蚀变信息。解译结果与矿区IKONOS图像的蚀变、岩性解译结果相吻合,蚀变提取形态一致,从而确定了ETM+图像信息提取结果的正确性,证实了在甲玛及其外围采用ETM+图像提取与矿化有关的信息是可行的。引入ETM+图像TM6波段,合成746假彩色图像进行构造信息的解译,并综合构造的、蚀变的、地质的研究成果,利用GIS技术进行信息的分层提取和叠加分析,在甲玛铜多金属矿矿区周边圈定了6个找矿远景区,这些远景区主要分布在甲玛矿区的周围及其北部一定的辐射范围内,是甲玛矿区外围找矿的重点。目前该研究区域除甲玛、驱龙外,其他地方的勘查程度均较低,但文中采用ETM+图像提取各种成矿信息,再用高空间分辨率的IKONOS图像提取成矿信息,开展对比研究,验证了圈定的找矿远景区的客观性和正确性,从而可用于指导甲玛的外围及冈底斯成矿带的区域找矿勘查实践。

After one year prospecting work at Jiama copper-polymetallic ore area,we found that the industrial orebodies spread well into the periphery of Jiama with great prospecting potential. In order to verify whether the peripheral area has mineralized and to provide the foundation for further exploration,we applied the remote sensing technique to the metallogenic prognosis of the ore district and peripheral belt. The ETM^＋ and image were used to conduct the principal component analysis,ratio analysis,and MNF transformation,and by means of Munsell transformation,the HLS image was built up. Based on the fact that the Fe^3＋,Si and OH^-displayed high brightness reflection during the image deciphering process,we set the threshold value and extracted the remote sensing metallization data. The deciphering results were coincident with the alterations and the lithological characteristics information extracted from deciphering the IKONOS images of mining areas,which demonstrated the correctness of the information extracted from the ETM^＋ and image and suggested the feasibility of using ETM^＋ and image to extract the relevant mineralization data in Jiama and its periphery. By introducing ETM^＋ and image TM6 wave band and combined with 746 false color image,the tectonic information was deciphered. Synthesizing the tectonic,alteration,and geological research results and using GIS method to conduct layering extraction of information and superimposing analysis,we delineated six perspective ore prospecting areas. These areas are mainly located on the surroundings and north of the Jiama mining area,where are the key places for ore prospecting. At present,except the Jiama and Qulong areas,most places of this region have had only low level exploration. However,by extracting various mineralization data both from ETM^＋ and image,and IKONOS image with high spatial resolution,and by making their comparison,we confirmed that the delineation of the perspective ore prospecting areas is objective and correct. In addition,this study may guide the practice of areal prospecting in periphery of Jiama and Gangdese metallogenetic belt.