河南省淅川县毛堂金矿区花岗斑岩锆石U-Pb年龄、Hf同位素特征及其地质意义

毛堂金矿是位于河南省"毛堂—蒲塘铜金矿带"上的一个小型金矿,矿体主要产于老田岩体的Ⅲ号岩体中,成矿作用与隐爆角砾岩和花岗斑岩关系密切。通过对与成矿有关的隐爆角砾岩和花岗斑岩进行LA-ICP-MS锆石U-Pb同位素测年,获得其成岩年龄分别为143.0 Ma±1.2 Ma和141.4Ma±1.5Ma,代表矿床的形成时代;对花岗斑岩进行Hf同位素测试,其εHf(t)值分布范围为-3.4～4.2,平均为1.6,显示其源区为镁铁质新生地壳。毛堂金矿形成于早白垩世,受花岗斑岩、隐爆角砾岩及其构造-裂隙控制,矿床类型属于隐爆角砾岩型金矿。

Zircon U-Pb age and Hf isotopic characteristics of granite porphyry in the Maotang gold deposit, Xichuan county, Henan province and their geological significance

Maotang gold deposit is a small gold deposit located in the copper-gold belt of Maotang-Putang, Henan province. The ore body mainly occurred in the No. 3 rock mass of the Laotian intrusion. The mineralization is closely related to cryptoexplosive breccia and granite porphyry. The LA-ICP-MS zircon U-Pb isotopic dating of the cryptoexplosive breccia and granite porphyry reveals that their diagenetic ages are 143.0 Ma ±1.2 Ma and 141.4 Ma±1.5 Ma, respectively, representing the age of the deposit formation; the Hf isotopic test of granite porphyry shows that the distribution range of the values is -3.4 to +4.2, with an average of 1.6. It shows that the magma source area is the newborn mafic crust. The Matang gold deposit was formed in the early Cretaceous, controlled by granite porphyry, cryptoexplosive breccia, structures and fractures at all levels, and belongs to the cryptoexplosion breccia type.