赣东北地区矽卡岩典型矿物形成与演化的光谱证据:以朱溪钨多金属矿为例SCIEI北大核心CSCD

朱溪是近年来在江西塔前-赋春成矿带发现的一个世界级超大型钨铜矿床。本文采用短波红外+热红外光谱技术对矿区13个钻孔进行了光谱测量,结合岩石-矿物地球化学分析,探讨了朱溪矿床矽卡岩中典型蚀变矿物的形成与演化过程,厘定了矽卡岩形成不同阶段矿物组合的光谱特征,构建了朱溪矿床的短波红外+热红外光谱勘查模型。研究发现:(1)区内不同矿物组合形成了明显的蚀变分带,由内向外依次为绢云母(富Si)+长石(岩体顶层蚀变,多期流体叠加综合作用)→外矽卡岩:钙铝榴石+透辉石+(绢云母)→透辉石+蛇纹石+绿泥(帘)石+滑石→绢云母(富Al)+绿泥(帘)石(基底不整合面蚀变);(2)Al-OH波长的移动可指示成矿流体压力、温度及pH值的变化;(3)研究区透辉石的形成、演化与矿体之间关系密切,虽然富矿体赋存于矽卡岩形成早期的透辉石-石榴子石蚀变带,但大量矿体则赋存于矽卡岩退蚀变阶段的蛇纹石-绿泥石蚀变带;(4)矿体的形成与流体的混合作用关系极大,伊利石光谱吸收特征能够指示外部冷水(大气降水或地下水)的灌入轨迹。

Spectral introductions of typical minerals during the periods of skarn formation and evolution at Zhuxi tungsten polymetallic deposit in Jiangxi Province

The Zhuxi tungsten polymetallic giant deposit is located in the Taqian-Fuchun metallogenic belt, Jiangxi Province. By measuring 13 drill cores with SWIR and TIR spectroscopy combined with geochemical analysis, we discussed the formation and evolution process of typical skarn minerals in the Zhuxi deposit, summarized their spectral characteristics, and constructed a spectral exploration model. It was found that: (1) different mineral assemblages form obvious alteration zones, i. e., sericite + feldspar (the top layer of the rock mass, caused by multistage fluid superposition probably) -> grossular + diopside + ( sericite) -> diopside + serpentine + chlorite (epidote + talc) -> sericite + chlorite (epidote) (alteration on the basement); (2) the shift of the Al-OH wavelength 2200nm can indicate the changes in pressure, temperature, and pH value of the ore-forming fluid; (3) diopside formation and evolution have a close relationship with ore bodies. Bonanza occurs in the grossular + diopside alteration zone, and a large number of ore bodies occur in the serpentine + chlorite alteration zone. It evidenced the importance of the fluid mixing and cooling for mineralization. The ore body emerged in the early stage of skarn formation, but the real enrichment stages occurred in the retrograde alteration stage; (4) the mixing fluid plays a key role in forming the deposit, and the illite spectrum can indicate the trace of the external cold water (atmospheric precipitation or groundwater).