基于高光谱岩心扫描的蚀变矿物光谱特征分带及其在找矿勘查中的应用——以山东省郗山稀土矿为例

Spectral Characteristics Zoning of Altered Minerals Based on Hyperspectral Ccore Scanning and Its Application in Ore Prospecting and Exploration——Taking Xishan Rare Earth Mining Area as an Example

本文对郗山稀土矿进行实物地质资料数字化工作的基础上,重点对该矿钻孔岩心进行高光谱扫描,利用光谱诊断特征进行蚀变矿物识别,识别出热液蚀变矿物主要有蒙脱石、伊蒙混层、伊利石、高岭石、碳酸盐矿物、金云母、绿泥石、白云母、蛋白石、石膏等,其中与稀土矿化关系密切的主要为金云母、绿泥石,总结了蚀变分带特征,提取主要蚀变矿物的光谱特征参数,实现主要蚀变矿物在钻孔垂向上的半定量表达。对主要蚀变矿物各自特征峰位置进行特征峰位移统计,发现主要蚀变矿物各自特征峰位移明显区域与矿化(矿体)段(热液蚀变带区域)具有良好对应一致性。其中,Al-OH峰位,即2200nm特征峰位置(Pos2000),在2190~2220nm之间进行“漂移”,且普遍大于2205~2210nm部位能准确指示热液蚀变带区域,可用于指示成矿环境,确定找矿方向及预测找矿,是郗山矿区稀土矿体找矿的又一重要标志。

On the basis of digitizing physical geological data of Xishan mining area,hyperspectral scanning of the borehole cores in the area have been carried out.By using spectral diagnostic characteristicss,altered minerals have been identifed.The hydrothermal altered minerals identified are mainly montmorillonite,illite,kaolinite,carbonate minerals,phlogopite,chlorite,muscovite opal and gypsum.Phlogopite and chlorite are closely related to rare earth mineralization.The characteristics of alteration zoning have been summarized,and spectral characteristic parameters of main alteration minerals have been extracted to realize the semi-quantitative expression of main alteration minerals in the vertical direction of the borehole.According to the statistics of the characteristic peak displacement of main altered minerals,It is found that the obvious characteristic peak displacement areas of main altered minerals have good correspondence with the mineralization(ore body)section(hydrothermal alteration zone area).Among them,the peak position of Al-OH,that is,the position of the characteristic peak(Pos2000)of 2200nm drifts between 2190~2220nm,and is generally larger than 2210nm.It can accurately indicate hydrothermal alteration zone area,and be used to indicate the ore-forming environment,determine the prospecting direction and predict the prospecting.It is another important indicator of rare earth ore body prospecting in Xishan mining area.By using this method,ore leakage has been found in the drill holes ZK5-1 and ZK48-3.It is verified that hyperspectral analysis technology can improve the exploration quality of rare earth ore in Xishan area,and provide some references for prospecting and exploration of the same type rare earth deposit.