新疆拉依克勒克隐伏斑岩矿床的发现、Re-Os同位素定年及地质意义

琼河坝是新疆环准噶尔斑岩成矿带中一个重要矿集区,在地表已发现数个斑岩型铜矿,但由于戈壁滩等第四系覆盖,给以地表矿化线索为主的找矿工作带来诸多困难。近年,利用综合地球物理探测手段,在第四系覆盖区取得重大深部找矿成果,在琼河坝中南部的拉依克勒克地区,发现一个深部斑岩铜(钼)矿床。该矿床是通过地表大比例尺激电扫面,确定一个北西走向、长5000m、宽500~1000m形态较完整的激电异常,通过钻探验证发现的。含矿岩体为一英云闪长岩体,不仅铜(钼)已经达到中型规模,金、铅锌也有很好的前景。在紧邻斑岩矿体的东南部位,还存在一个隐伏的矽卡岩型富铜-铁矿体。本文在对英云闪长岩的蚀变作用、地球化学、成矿特征研究基础上,对蚀变岩中6件辉钼矿样品的Re-Os同位素年龄做了测定,其加权平均模式年龄为411.1±2.4Ma,与本地区其它斑岩矿床的成矿年龄基本一致,进一步确证了琼河坝地区上志留到下泥盆世是区内重要的斑岩型铜多金属成矿期。这对进一步明确琼河坝地区斑岩型矿床的成矿环境和找矿方向有重要意义。

Discover of Layikeleke insidious porphyry deposit in Xinjiang, Re-Os isotope dating and its geological implications

Qiongheba ore concentration area was important component of porphyry copper metallogenic belt in Junggar, Xinjiang. Several porphyry copper deposits have been found in this area, but the extensive distribution of the Gobi desert makes surface prospecting difficulty in this area. In recent years, successfully use of comprehensive geophysical exploration methods in this area, has made a new buried copper (molybdenum) porphyry deposit found. The findings was mostly based on surface Induced Polarization (IP) methods, which defined a NW-trending, 5000m long and 500~1000m wide IP anomaly, and deep drilling. The drilling verification indicates that the IP anomaly caused by concealed copper (molybdenum) mineralization tonalite body. The tonnage of the deposit has reach to medium large size in copper (molybdenum), the associated gold and lead-zinc are also in good prospect. A concealed skarn type copper iron-rich ores which close the tonalite body is also found. Based on the preliminary study on petrology, geochemistry, metallogenic characteristics of tonalite, the Re-Os isotope dating was carry out on the six molybdenite samples, the weighted mean age is 411.1±2.4Ma. It is consistent with mineralization age of porphyry copper deposit in this area. These age characteristics further evidenced that there is a magma-hydrothermal polymetallic mineralization event in this area during the Upper Silurian and Lower Devonian. All these indicate that Layikeleke metallogenic province has great prospection potential, and has important significance in deepening our understanding of magmatic hydrothermal metallogenesis in this area.