矽卡岩型金铜矿床蚀变矿物热红外-短波红外光谱特征及其指示意义——以鄂东南鸡冠咀矿床为例

TIR-SWIR characteristics of alteration minerals and exploration implications in skarn gold-copper deposits: A case study of Jiguanzui deposit, Edongnan ore concentration area

中文关键词:热红外  短波红外  勘查标识  指针矿物  鸡冠咀

keywords:TIR  SWIR  exploration index  indicator minerals  Jiguanzui

中文摘要:矽卡岩型矿床普遍发育矿化蚀变分带特征，然而如何快速识别蚀变分带、利用蚀变分带指示找矿方向还有待深入研究。鸡冠咀是长江中下游成矿带内典型的大型矽卡岩型金铜矿床，伴生钼矿化。前人对该矿床退化蚀变阶段绿泥石和白云母开展了短波红外光谱的研究，但热红外-短波红外光谱联合，开展多种矿物勘查指标的研究相对薄弱。鉴于此，文章以典型钻孔为研究对象，在详细岩芯编录的基础上，对钻孔岩芯开展热红外-短波红外光谱分析。结果表明，石榴子石的Pos11500值小于11410 nm时指示Mo矿化，大于11410 nm时则指示Cu矿化；靠近铜矿体处，石榴子石T吸收谷Pos11500、白云母Al-OH吸收峰Pos2200和绿泥石Fe-OH吸收峰Pos2250均明显向长波方向偏移。碳酸盐矿物Pos6500高值（>6500 nm）且Pos11300高值（>11410 nm）或中等Dep2350值（反射率为0.1~0.2）、石英Pos8625高值（>8630 nm）或Pos12610高值（>12630 nm）与矿化在空间上存在较好的耦合性。因此，文章提出石榴子石Pos11500、石英Pos8625、Pos12610和碳酸盐矿物Pos6500、Pos11300、Dep2350可以作为矽卡岩型金铜矿床找矿勘查的多矿物多光谱指标，为建立矽卡岩型矿床热红外-短波红外光谱勘查标识提供参考。

Abstract:Skarn deposits commonly exhibit mineralization and alteration zoning characteristics. However, how to rapidly identify alteration zoning and utilize it to guide exploration still requires further research. The Jiguanzui deposit, a typical large skarn Au-Cu deposit with associated molybdenum mineralization in the Middle-Lower Yangtze River Metallogenic Belt, has previously been studied for chlorite and muscovite in retrograde alteration stage using short-wave infrared (SWIR) spectroscopy. However, research on multi-mineral TIR-SWIR spectroscopic integration for indicator mineral exploration remains relatively underdeveloped. This paper focuses on typical drill holes at Jiguanzui, conducting detailed drill core-logging combined with TIR-SWIR spectral analysis. The results demonstrate that: 1) Garnet Pos11500 values <11410 nm indicate Mo mineralization, while values >11410 nm correspond to Cu mineralization; 2) Near copper ore bodies, characteristic absorption peak of garnet (Pos11500), muscovite Al-OH absorption peak (Pos2200), and chlorite Fe-OH absorption peak (Pos2250) all shift significantly towards longer wavelengths; 3) Carbonate minerals with high Pos6500 (>6500 nm) and Pos11300 (>11410 nm) values combined with moderate Dep2350 (reflectance of 0.1-0.2), as well as quartz showing high Pos8625 (>8630 nm) or Pos12610 (>12630 nm) values, exhibit strong spatial correlation with mineralization. Therefore, we propose that multi-mineral spectral indicators including garnet Pos11500, quartz Pos8625/Pos12610, and carbonate Pos6500/Pos11300/Dep2350 can serve as effective exploration pointer. This study provides reference for establishing TIR-SWIR spectral exploration indicators in skarn Au-Cu deposits.