胶东和鲁西地区中生代成矿作用重大差异性的内在因素

胶东和鲁西地区被沂沭断裂带所分隔 ,在中侏罗世末期 ,由于郯庐断裂带发生大规模左旋平移运动 ,二个地区最终拼合在一起。胶东和鲁西地区的金等多金属成矿作用发生在早白垩世 ,但其成矿作用的规模、矿床类型和成矿机制均存在很大的差别。研究表明 ,鲁西地区长期处于华北板块内部 ,而胶东地区则是长期处于华北板块的边缘地带 ,它曾经历了前寒武纪强烈的地质作用、早古生代洋—陆俯冲与碰撞造山作用、晚古生代缓慢隆起、印支晚期至燕山早期的陆—陆俯冲与强烈挤压以及燕山晚期岩石圈减薄与大规模构造 岩浆活动的复杂的构造环境和地质演化过程。因此可以认为 ,除上述综合地质构造作用因素外 ,中生代库拉—太平洋板块向欧亚大陆俯冲以及沂沭断裂带的强烈活动是直接导致早白垩世胶东地区产生突发性巨量成矿作用的重要的动力学条件

The intrinsic factors causing the significant differences in Mesozoic mineralization between Jiaodong and Luxi areas

Jiaodong and Luxi areas are separated by Yishu fault. These two areas were put together at the end of Middle Jurassic owing to the large-scale sinistral translative motion of Tan-Lu fault. The mineralization of gold-polymetallic ore deposits in the above two areas took place in the Early Cretaceous. But there are the significant differences in metallogenic scale, the ore deposit types and metallogenic mechanism between Jiaodong and Luxi areas. A comparative study shows that Luxi area is located within the North China Plate and Jiaodong area in the margin of the North China Plate for a long time. It should be pointed out that Jiaodong area had undergone following complex tectonic environments and geological process:the Precambrian complex geological process, the Early Palaeozoic oceanic-continental crustal subduction and collision orogeny, the Late Palaeozoic slow uplift, the continental-continental crustal subdiction and intensive compression from Late Indosinian to Early Yanshan periods, as well as the Late Yanshan lithosphere thinning and large-scale tectonic-magmatic activities. It is proposed that the subduction of the Kula-Pacific Plate beneath the Euro-Asia Plate and the intensive activities of Tan-Lu fault zone are the important dynamic conditions resulted directly in sudden occurrence of large-scale mineralization in the Early Cretaceous in Jiaodong area besides the above comprehensive geological structural factors.