胶东伟德山地区铜钼多金属矿锆石U-Pb法测年及其地质意义

U-Pb dating of zircons from the Weideshan molybdenum copper polymetallic deposits in Jiaodong Peninsula, China, and its geological significance.

伟德山地区构造位置上处于苏鲁——大别造山带鲁东段,该区广泛出露中生代燕山晚期花岗岩,岩体内部及外围已发现十余处钼、铜及多金属矿床(点),为一重要的多金属矿产地。本文利用LA-ICP-MS锆石U-Pb同位素定年技术对该区两个典型矿床矿化花岗岩开展了年代测定,获得了两个岩浆锆石U-Pb法加权平均年龄分别为113.4±1.8Ma和114.2±2.1Ma,与前人所测得的该区花岗岩SHRIMP锆石U-Pb同位素年龄108±2Ma,117.7±2.9Ma～113.4±2.5Ma较一致,结合中国东部地区花岗岩体与其相应的有色金属矿化时间差异的研究成果,认为伟德山地区铜钼成矿时代应在110Ma左右,属燕山晚期多金属成矿亚系列。区域上的研究表明,该区成岩成矿作用处于早白垩世古太平洋板块相对亚洲大陆俯冲导致的弧后扩张环境,为中国东部岩石圈减薄过程中壳幔相互作用的产物。

The Weideshan area, located in the Ludong district of the Sulu-Dabie Orogen, is a very important polymetallic mineralization zone. There are a series of medium-and small-sized Mo-Cu-Pb-Zn-Au-Ag polymetallic deposits （occurrences） distributed in and around the Weideshan granite, which is the main rock in the area. The U-Pb dating of the zircons of the mineralization granites from two typical deposits were measured, and all the zircons are magmatic origins. The weighted average U-Pb ages of the zircons from the two granites are separately 113.4±1.8Ma and 114.2±2.1Ma,identical with the results （108±2Ma, 117.7±2.9Ma～113.4±2.5Ma） by zircon SHRIMP technique measured before. Based on the studies on the difference between the granites and the related mineralization forming age in East China, it was suggested that the copper and molybdenite mineralization in Weideshan area was about 110Ma, belong to the Yanshanian polymetallic deposits metallogenetic series. Coupled with previous researches, it was suggested that the petrologenesis and metallogenesis in Weideshan area was probably the result of crust-mantle interactions under the geodynamic setting of the lithospheric thinning and extension.