高光谱标志性蚀变矿物组合在找矿预测中的应用研究——以东昆仑东—西大滩一带金矿床为例

摘要

The East Kunlun area is a very important and promising metallogenic belt in Qinghai Province,where developed an integrated orogenic gold metallogenic series.The metallogenic geological conditions in Dongdatan and Xidatan area have been analyzed in this paper.The results indicate that a good location-vacancy for metallogenic series of orogenic gold deposits exists in Dongdatan and Xidatan.Anomaly extracting results of hyperspectral data (CASI/SASI) indicate that seven types of altered minerals were mainly developed in this area,such as siderite,hornblende,chlorite,epidote,dolomite,calcite,long-medium-short wave of sericite.Different types of altered mineral groups reflect the distribution of shear zones in this region.Though developing the ground spectral measurements of the typical deposit by ASD instrument,this study summarizes the spectral characteristics of different geological units and altered minerals.It proposes that siderite + dolomite + medium wave sericite group is the iconic alteration mineral assemblages in this region.The prospecting criterion is the brittle-ductile shear zone that developed jarosite + limonitization.Combining the X-ray diffraction analysis of mineral composition in these rocks,it shows that the gold mineralization is closely related to regional metamorphism carbonate formnearation,which was controlled by the nearly EW brittle-ductile fault.Then,based on the iconic altered mineral assemblage of hyperspectrum anomaly and it predicts that there are two shear zones located in Wushibada Valley and Xidatan,with good prospecting potential of gold deposits.It also builds the gold prospecting model basing on high spectral information.%青海东昆仑是中国重要的、极富潜力的多金属成矿带,发育有完整的造山型金矿成矿系列.笔者通过东昆仑成矿带东-西大滩研究区成矿地质条件分析,认为该区存在较好的造山型金矿成矿系列空间缺位.航空高光谱遥感异常提取表明,区内发育有菱铁矿、角闪石、绿泥石、绿帘石、白云石、方解石和长-中-短波云母等7类蚀变矿物,不同类型的蚀变矿物组合较好反映出区内构造带的展布.结合区内典型矿床地面ASD光谱测量,对不同地质单元、矿化带的光谱特征分析总结.提出该区金矿床标志性蚀变矿物组合为菱铁矿+中波绢云母+白云石,地表找矿标志为黄钾铁矾+褐铁矿化发育的脆-韧性剪切带.结合矿化蚀变带的矿物成分X衍射分析,认为金矿化受近东西向脆-韧性断层控制.进而,通过标志性蚀变矿物组合找矿预测技术对区内高光谱异常进行筛选及查证.指出在西大滩、五十八大沟一带具有剪切带型金矿床良好找矿潜力,并构建该区基于高光谱信息的金矿床找矿模型.