基于岩心高光谱数据的蚀变矿物精细分类与找矿勘查应用研究——以龙宝山稀土矿区为例

Minerals Based on Core Hyperspectral Data——Taking Longbaoshan Rare Earth Mining Area as an Example

摘要:

本次工作在龙宝山矿区进行实物地质资料数字化工作的基础上，对该区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、白云母等，其中与稀土矿化关系密切的主要为金云母，总结了蚀变分带特征，同时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）对应性良好。其中，AlOH峰位，即2 200 nm特征峰位置（Pos2000），在2 190~2 220 nm之间进行“漂移”，且普遍大于2 205~2 210 nm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等方面，该特征可作为龙宝山矿区稀土矿体找矿标志。同时，利用地球化学、岩相学等方法验证了主要蚀变矿物的光谱特征参数（特征峰位移）、特定元素组合能准确识别热液中心，并对成矿环境进行了分析研究，对于该类型稀土矿产勘查具有重要指导意义。

Abstract:

Based on the digitization of physical geological data in Longbaoshan mining area, hyperspectral scanning on the drilling core in the area has been carried out. By using spectral diagnostic characterstics, alteration minerals have been identified. Hydrothermal alteration minerals mainly include montmorillonite, illite mixed layer, illite, kaolinite, carbonate minerals, gold mica, chlorite and muscovite. Among them, gold mica is closely related to rare earth mineralization. The alteration zoning characteristics have been summarized, and spectral characteristic parameters of main alteration minerals are extracted to achieve semi quantitative expression of main alteration minerals in the vertical direction of the drilling holes. Characteristics of main alteration minerals have been statistically analyzed.The spectral characteristic parameters of main altered minerals have been extracted to achieve semi quantitative expression of main altered minerals in the vertical direction of the borehole. The displacement of characteristic peaks of main altered minerals has been statistically analyzed. It is found that the areas with obvious peak displacement of main altered minerals corresponded well with the mineralization (ore body) section (hydrothermal alteration zone area). Among them, the Al-OH peak position, which is the characteristic peak position at 2200 nm (Pos2000), drifts between 2190~2220 nm and generally indicates hydrothermal alteration zone area in areas greater than 2205~2210 nm. It can be used to indicate the mineralization environment, determine the direction of prospecting, and predict prospecting. This characteristics can serve as a marker for rare earth ore body prospecting in Longbaoshan mining area. At the same time, spectral characteristic parameters (peak shift) and specific element combinations of main altered minerals are verified by using geochemical, petrographic and other methods to accurately identify hydrothermal centers. The ore-forming environment has been analyzed and studied. It has important guiding significance for the exploration of rare earth minerals.