基于红外光谱技术的西藏多不杂斑岩型Cu-Au矿床蚀变及矿化特征研究-以钻孔ZK3112为例

Alteration and Mineralization Characteristics of the Duobuza Porphyry Cu-Au Deposit in Tibet Based on Infrared Spectroscopy Technology:An Example of the Drill Hole ZK3112

多不杂斑岩型Cu-Au矿床是西藏多龙矿集区内的三大矿床之一,随着该区找矿工作逐渐向深部及外围展开,需要较新的技术方法与勘查理念。本文通过短波红外(SWIR)技术对矿区内ZK3112钻孔开展光谱填图工作,在厘清钻孔内蚀变矿物类型、空间分布及矿物组合分带的基础上,对主要蚀变矿物的波谱特征参数变化规律进行统计。研究发现绢云母Al-OH2200Pos的低值(<2200 nm)和绿泥石Fe-OH2250Pos的高值(>2254 nm)均可以指示钻孔内蚀变较强的区域,可快速定位热液矿化中心,是有效的找矿勘查标识。利用ASTER数据提取区域上羟基蚀变信息,发现在多个矿区范围内均出现了与多不杂同样的羟基异常,这说明针对蚀变矿物波谱特征所建立的找矿勘查标志可能同样适用于本区域其他同类型矿床。该研究成果可为多不杂矿床及区域内同类型矿床的找矿勘查工作提供新方法、新理念。

The Duobuza porphyry Cu-Au deposit is one of the three major deposits in the Duolong ore concentration area in Tibet.With the development of prospecting in depth and periphery,new technical methods and exploration ideas are needed.The SWIR(short-wave infrared)technique was used to conduct spectral mapping to the drill hole ZK3112 in the mining area.On the basis of clarifying the type,spatial distribution and mineral assemblage zoning of altered minerals in the borehole,statistical analysis was made on the variation rules of spectral characteristic parameters of main altered minerals.It is inferred that the low value of Al-OH2200Pos(<2200 nm)of sericite and the high value Fe-OH2250Pos(>2254 nm)of chlorite can both indicate the area with strong alteration in the borehole and quickly locate the hydrothermal mineralization center,which are effective prospecting and exploration indicators.By using ASTER data to extract regional hydroxy alteration information,it is found that the other deposits in the region also display similar hydroxy anomalies to the Duobuza deposit,which indicates that the established prospecting and exploration indicators for the spectral characteristics of altered minerals may also be applicable to other similar ore deposits in the region.The achievements provide new methods and new ideas for future prospecting and exploration of the Dubuza deposit and the same type of deposits in the region.