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内蒙古阿拉善地区朱拉扎嘎金矿是新近发现的特大型层控改造型金矿床,该矿床以产于中元古界地层中和具有巨大的找矿潜力而引人注目。容矿岩石主要为钙质粉砂岩、粉砂质板岩。采用颗粒锆石U-Pb法和40Ar/39Ar法对成矿期花岗斑岩、成矿后期闪长玢岩和含金石英-硫化物矿体进行了年龄测定,获得成矿期花岗斑岩的锆石U-Pb年龄为(304±5)Ma,成矿后闪长玢岩为(259±6)Ma,朱拉扎嘎金矿体中石英的40Ar/39Ar年龄为(282.3±0.9)Ma。这一结果揭示,朱拉扎嘎金矿是华力西晚期形成的,这与前人采用Rb-Sr法测得矿石的等时线年龄(275±6)Ma是一致的。结合阿拉善地区的呼伦西白金矿和欧布拉格铜金矿都是华力西晚期形成的,表明华力西晚期是中国西部最重要的金(铜)矿化期。
The Zhulazaga gold deposit in the Alashan region of Inner Mongolia is a newly discovered super-large-scale stratified controlled-alteration gold deposit that has attracted the attention of the Middle Proterozoic strata and its huge prospecting potential. The ore-bearing rocks are mainly calcareous siltstone and silty slate. Granite porphyry during the ore-forming stage, diorite porphyrite and gold-bearing quartz-sulfide ore bodies during the late stage of metallogenesis were determined by U-Pb and 40Ar / 39Ar methods. The zircon U-Pb ages of the rocks are (304 ± 5) Ma, (259 ± 6) Ma after mineralization, and 40Ar / 39Ar ages of quartz in the Zhuolazaga gold deposit are (282.3 ± 0.9) Ma. This result reveals that the Zhulazaga gold deposit was formed in the late stage of the Variscian, which is consistent with the isochron age (275 ± 6) Ma measured by the Rb-Sr method. The Hulunseibai gold deposit and the Oraguela copper-gold mine combined with the Alashan region were all formed in the late stage of the Warisi, indicating that the late Variscan stage is the most important gold (copper) mineralization stage in western China.