浙江泰顺龟湖叶腊石矿床热液蚀变短波红外光谱分析

蚀变岩帽与斑岩体关系密切,具有形成斑岩-浅成低温热液型矿床的潜力.位于浙闽交界的龟湖地区发育规模巨大的蚀变岩帽(>30 km2),形成了龟湖超大型叶腊石矿床,矿体属于岩帽的一个分带.矿床及其围岩蚀变主要由粒度微小或隐晶质的层状硅酸盐蚀变矿物组成,矿物之间差别极为细微,仅凭肉眼难以区分.短波红外光谱技术可以有效识别这些蚀...

Short-wavelength infrared spectral analysis of hydrothermal alteration associated with Guihu pyrophyllite deposit in Taishun, Zhejiang Province, China

Lithocaps are closely related to porphyry, and have the potential to find porphyry-epithermal deposits. Massive lithocaps(>30 km²) developed in the Guihu area at the border of Zhejiang and Fujian, forming the Guihu super-large pyrophyllite deposit, the ore belongs to a zone of the lithocaps. The deposits and their wall-rock alteration are mainly composed of layered silicate alteration minerals with small particle size or aphanitic, and the differences between minerals are very subtle and difficult to distinguish with the naked eye alone. Short-wave infrared(SWIR) spectroscopy can effectively identify the composition of these altered minerals. Therefore, this paper takes the Guihu super-large pyrophyllite deposit as an example, and makes a detailed study of the alteration minerals by short-wave infrared spectroscopy. The reticular sampling and short-wave infrared spectroscopic analysis of the mining area identified 17 kinds of hydroxyl-containing minerals, such as pyrophyllite, paragonite, muscovite, kaolinite, etc., and divided the surface alteration of the mining area into three phases of strong silicified zone, advanced argillitization zone and argillitization zone. Within the mining area, the low value area of the sericite mineral spectral characteristic parameter Pos2200 and the high value area of IC are mainly in the silicified and high-grade argillaceous zone, indicating a higher alteration temperature;the pyrophyllite spectral characteristic parameters Pos1400 and Pos2160 FWHM which is consistent with the abnormal value area of the sericite characteristic parameter. The abnormal value area of the above indicators coincides at about 300 m southeast of Yangtian Lake in the mining area, and there may be a hydrothermal center. Lithocaps in Guihu pyrophyllite deposit and Fujian Zijinshan high epithermal deposit have a similar alteration zone characteristics, we believe that the lithocaps have the potential of porphyry-epithermal deposit.