内蒙古干珠尔善德银铅锌矿床的短波红外光谱研究

内蒙古干珠尔善德银铅锌矿床是一处构造裂隙充填型脉状矿床,其围岩蚀变作用强烈,伊利石-绢云母类蚀变矿物广泛发育于围岩中,与银铅锌矿化作用密切相关。对围岩开展短波红外光谱测量,可以计算蒙脱石-伊利石-绢云母类矿物的伊利石结晶度(SWIR-IC),从而定量地确定该类蚀变作用的强度。该方法有效性试验研究表明,SWIR-IC与(Pb+Zn)%的品位具有很好的正相关关系,即围岩的伊利石-绢云母化蚀变作用越强,铅锌矿化作用也越强。通过对干珠尔善德详查区进一步开展短波红外光谱测量,在地表圈出了5处规模较大的SWIR-IC异常(IC1~IC5),其中IC1和IC4异常与银铅锌矿化带的位置相一致,IC5则可以作为下一步找矿的靶区。在热液脉状银铅锌矿床的勘查工作中,对围岩开展系统的短波红外光谱测量工作,可以定量地显示伊利石-绢云母化蚀变的强度,指示热液活动中心,从而寻找银铅锌矿体的所在,但需同时确认绢云母是否为热液蚀变成因。

Short-wave infrared spectroscopy study on wall rock alteration of the Ganzhuershande silver-lead-zinc deposit in Inner Mongolia

The Ganzhuershande Ag-Pb-Zn deposit in Inner Mongolia is a structural crack filling vein-type deposit, with intense wall rock alteration. Illite-sericite group minerals developed pervasively in the wall rock, which are closely associated with the Ag-Pb-Zn mineralization. Short-wave infrared spectra tests on wall rock permits to calculate the illite crystallinity (SWIR-IC) of smectite-illite-sericite group minerals, thus further determining the alteration intensity. The results of method validity tests show that SWIR-IC is positively correlated to the grade of (Pb+Zn)%. In other words, the more intense the sericitization developed, the stronger the Pb-Zn mineralization occurred. The short-wave infrared spectra measurement over the Ganzhuershande detailed exploration district has delineated a total of five SWIR-IC anomalies on the surface (IC1 ~ IC5). The IC1 and IC4 are coincident with Ag-Pb-Zn mineralization zones, and the IC5 will be the next exploration target. During the exploration program of hydrothermal vein-type Ag-Pb-Zn deposits, short-wave infrared spectra survey for wall rock can determine the intensity of illite-sericite alteration quantitatively and indicate the center of hydrothermal activity. However, whether the origin of sericite is hydrothermal should be also confirmed.