浙江遂昌金多金属矿床热液蚀变短波红外光谱分析

被誉为“江南第一金矿”的遂昌金多金属矿床(简称“遂昌金矿”)可采储量逐渐枯竭,随着找矿的深入,亟需新的找矿思路或技术手段来取得找矿突破。遂昌金矿区发育明显的热液蚀变,根据热液蚀变来指导找矿是一种可行的思路。利用短波红外光谱分析技术来解剖蚀变晕的矿物组成、组合、参数等信息,进而评估与成矿有关的关键信息。通过对地表蚀变岩、穿切金矿体的井下巷道及现存的穿切金矿体的一个钻孔和穿切钼矿体的两个钻孔进行采样和测试分析,提取出绢云母类、绿泥石类、高岭石类、蒙脱石类和碳酸盐类等蚀变矿物,其中绢云母类矿物最为发育,绿泥石类次之。结果表明:绢云母类矿物和绿泥石的短波红外光谱特征在空间上呈现规律性的变化。绢云母Al—OH吸收峰位(Pos2200)越小、吸收峰深度越深时,伊利石结晶度越高; 同时,越靠近矿体伊利石结晶度越大,Al—OH吸收峰位(Pos2200)越小,绿泥石Fe—OH吸收峰位(Pos2250)越大。这一规律表明短波红外光谱分析有助于查明矿床蚀变分带,为遂昌金矿的进一步找矿勘查提供科学依据,同时短波红外技术可以作为覆盖区同类型矿床的一种勘查手段。

Short Wavelength Infrared Spectral Analysis of Hydrothermal Alteration Associated with Suichang Gold Polymetallic Deposit in Zhejiang,China

Suichang gold polymetallic deposit in Zhejiang is gradually depleted in recoverable reserves. With the deepening of ore prospecting, new ideas or technical methods are urgently needed to make a breakthrough in prospecting. Obvious hydrothermal alteration is developed in Suichang gold mine. It is a feasible idea to guide ore prospecting according to hydrothermal alteration. The short wavelength infrared spectral analysis technology was explored to dissect the mineral composition, association, parameters and other information of alteration halo, and then the key information related to mineralization was evaluated. Minerals including sericite, chlorite, kaolinite, montmorillonite and carbonate are extracted based on the sampling and testing analysis of surface altered rock, underground roadways through gold orebodies, one existing borehole through gold orebodies and two boreholes through molybdenum orebodies. Among the alteration minerals, sericite is the most widely distributed, followed by chlorite. The results show that the short wavelength infrared spectral characteristics of sericite and chlorite present regular spatial changes. In sericite, the smaller the Al—OH absorption peak(Pos2200)and the deeper the absorption depth, the higher the illite crystallinity; at the same time, the illite crystallinity and Fe—OH absorption peak(Pos2250)of chlorite increase with decreasing distances to orebody, while the Al—OH absorption peak(Pos2200)shows the opposite trend. This rule indicates that a short wavelength infrared spectral analysis will be helpful to characterize the alteration zone of Suichang gold polymetallic deposit and provide a scientific basis for its further prospecting and exploration. In addition, the short wavelength infrared spectral analysis technology can be used as an exploration tool for the same type of deposit in other volcanic rock covered area.