东昆仑哈日扎多金属矿区花岗斑岩与闪长岩LA-ICP-MS锆石U-Pb年龄及其地质意义

    LA-ICP-MS zircon U-Pb age and geological significance of granite porphyry and diorite in the Harizha polymetallic ore district, East Kunlun Mountains

    • 摘要: 哈日扎多金属矿区具有多期成矿作用,成矿母岩为闪长岩、花岗斑岩和花岗岩。通过对闪长岩和花岗斑岩进行LAICP-MS锆石U-Pb测年,获得3个样品锆石年龄。样品TC22-3为闪长岩,年龄集中在413±5.4~433±5.5Ma之间,年龄加权平均值为424.7±4.8Ma;DK19-1为花岗斑岩,年龄集中在233±2.4~251±2.9Ma之间,年龄加权平均值为242.6±2.6Ma;DK23-1为花岗斑岩,206Pb/238U年龄集中在235±4.0~262±6.5Ma之间,年龄加权平均值为245.8±3.4Ma。样品DK23-1和DK19-1的锆石年龄代表印支期岩体年龄,与东昆仑地区印支期发生过较大规模岩浆活动事件相耦合,并且指示了哈日扎矿区主要的成矿年代;样品TC22-3形成时代为志留纪,记录了东昆仑早古生代的岩浆活动,也说明在志留纪该矿区已经发生了矿化现象。另外,东昆仑地区的晚志留世花岗岩可能与东昆仑早古生代洋盆闭合后的碰撞造山作用有关。

       

      Abstract: The Harizha ore district has multiple periods of mineralization and the ore-forming parent rocks are granite porphyry, diorite and granite The authors obtained three zircon LA-ICP-MS U-Pb ages from diorite and granite porphyry. Samples TC22-3, DK19-1 and DK23-1 are dioritic granite porphyry and granite porphyry respectively. Sample TC22-3, DK19-1 and DK23-1 have the ages of 424.7±4.8Ma, 242.6±2.6Ma and 245.8±3.4Ma, respectively. Sample DK19-1 and DK23-1 ages belong to Indosinian period and reflect large-scale magmatic activities and also indicate major metallogenic chronology of the Harizha ore district. Sample TC22-3 records the Early Paleozoic magmatic events in the East Kunlun Mountains and can also explain the existence of the Silurian mineralization. The other Late Silurian granite was related to the collision orogenesis after closing of the Early Paleozoic ocean basin.

       

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