胶东地区壳-幔作用与金成矿效应

胶东矿集区的形成、演化受地幔剪切带和深部流体控制,壳-幔作用和地球动力体制转换是成矿物质活化→运移→聚集→成矿的基本动力学保障,构造应力场转换是其重要表现形式。郯庐断裂是深切地幔的成熟岩石圈断裂,是富含地幔流体的幔内剪切带,其内发生流体-热-化学-物理耦合,决定了胶东矿集区的形成与分布规律,其剪切深熔作用是成矿物质活化、运移的重要驱动力,是成岩成矿作用发生的根本原因之一。地幔流体通过壳-幔相互作用,形成碱交代热液,沿郯庐断裂带向上发散、运移,将含矿流体系统输运到更高的层位,为流体成矿作用提供了矿源。胶东金矿集中区为相对于周边的地幔隆起区,金矿床产于莫霍面的梯度变化处或变形部位,凹陷区局部隆起部位金的成矿强度明显小于其它地段。超大型矿床决定于超大型碱交代岩规模和深部流体活动强度及成矿元素的高效富集效应,在早期剪压体制下,流体组分、成岩组分和成矿组分大量交换运移;晚期剪张体制下,热液析出、交代作用和成矿作用易于发生。

CRUST-MANTLE INTERACTION AND ORE-FORMING EFFECT OF GOLD ORE DEPOSITS CONCENTRATED AREA IN JIAODONG , SHANDONG , CHINA

Metallogenic system is the component of materials system of the Earth. Metallization is one of the expression forms of dynamic functions of the Earth. The formation and evolution of deposits concentrated area is related to crust-mantle evolution and dynamic action of the Earth. Dynamics is the key to determine evolution and final results of the deposits concentrated area. The research of dynamics of formation and evolution of deposits concentrated area is a breakthrough at the traditional metallogenic theory, and it is of great theoretical and practical significance. The gold ore deposits concentrated area in Jiaodong is the product of geological processes in regional scale. Its formation and evolution are controlled by the mantle shear zone, deep-seated fluids and the maturity of continental lithosphere and deep-fault, and are closely related with the formation and evolution of the Tancheng-Lujiang Fault Zone and plate subduction-collision-jams. The occurrences and processes of deposits concentrated area are controlled by the crust-mantle interaction and the transformation of dynamic system of the Earth, and are interconnected with the formation and evolution of the Tancheng-Lujiang Wrench Fault System. The Tancheng-Lujiang Fault is mature lithosphere fault of deep mantle-cut and a fluids-bearing mantle shear zone where the coupling of fluid-heat-chemistry-physics occurred. The shear-anatexis of the Tancheng-Lujiang Fault is one of basic power generating of lithogenesis and mineralization, and is one of basic reasons of ore-forming reactivation and migration. Mantle-fluids changed into alkali metasomatizing solution by crust-mantle interaction. And with ore fluid system being migrated to upper horizon through this solution diverging and migrating along the Tancheng-Lujiang Fault, the source of ore is supplied. The gold ore deposits concentrated area in Jiaodong is a mantle upwelling area where the gold ore deposits are located at gradient variation and deformation places of Moho. The intensity of mineralization in upward district of down-warping region is minor than that of other districts. The scale of super-large alkali metasomatism, the intensity of ore fluids and enriched effect of ore-forming elements controls super-large deposits. At the end of the paper, based on the researches of the transformation of tectonic and the dynamics of metallogenesis, the authors put forward that the transformation of tectonodynamic mechanism gaves a dynamic guarantee for the mineralizing materials to react, transport, gather and mineralize, then the transformation of tectonic stress field is one of its most manifestation, and the mineralization of gold took place on the space-time interface where shear-strain deformed structural lithofacies transformed to shear-tension deformed structural lithofacies.