地幔热柱多级演化及其幔枝构造成矿控矿——以胶西北郭家店幔枝构造为例

Multistage evolution of mantle plume and the ore-forming and ore-controlling role of mantle branch structure:A study on mineralization of the Guojiadian mantle branch structure in northwestern Jiaodong

文章简要介绍了幔枝构造成矿理论,探讨了幔枝构造的特征、单元划分、断裂构造体系以及成矿控矿作用。在燕山运动晚期,华北东部地区进入了以伸展构造为主的地幔热柱演化阶段,在胶西北地区形成了莱阳地幔亚热柱及其外围郭家店、栖蓬、牟乳等幔枝构造。其中,郭家店幔枝构造于燕山运动晚期发生强烈的构造活动,总体形成了以焦家断裂为主的拆离带和与其相交的以三山岛断裂为反向铲状断裂的构造体系,同时控制着玲珑、焦家、三山岛等一系列大型—超大型矿床的形成。在众多成矿控矿因素中,区域性断裂构造是重要的主导性因素,既为成矿流体的运移提供了通道,又为成矿储矿提供了有利空间。深源含矿流体可通过地幔热柱→地幔亚热柱→幔枝构造→有利构造扩容带,即脆韧性-韧脆性剪切带、侵入岩体的内外接触带、密集的构造裂隙带、各种脉岩与围岩的接触带等有利构造部位集聚成矿。近年来在胶西北深部勘查发现,浅部沿断裂展布的若干个大—中型金矿在其深部的成矿蚀变构造带可能是连为一体的,一起组合成为超大型金矿。

This paper briefly introduces the establishment of metallogenic theory of mantle branch structure,the characteristics,unit division and fault structure system of mantle branch structure,as well as its mineralization.During the late Yanshanian movement,the eastern part of North China entered the evolutionary stage of mantle plume dominated by extensional structures.The Laiyang mantle sub plume and its surrounding mantle branch structures,such as Guojiadian,Qipeng and Mouru,were formed in northwestern Jiaodong.The Guojiadian mantle branch structure was strongly active in the late Yanshanian,which generally formed the Jiaojia fault as a main detachment zone in the hanging wall and the Sanshandao fault as a reverse shovel fault intersecting with the Jiaojia fault,and controlled the formation of a series of large and super large deposits such as the Linglong,Jiaojia and Sanshandao gold deposits.Among many oreforming and controlling factors,regional fault structure should be an important dominant factor,which not only provides channels for the migration of ore-forming fluids,but also provides favorable spaces for the precipitation of ore-forming materials.The deep source ore-bearing fluids are concentrated and mineralized through mantle plume,sub-mantle plume,mantle branch structure,favorable structural expansion zones successively,i.e.brittle ductile-brittle shear zone,internal and external contact zone of intrusive rock mass,dense structural fracture zone,contact zone between vein rock and surrounding rock.In recent years,deep geological exploration in northwestern Jiaodong has found that several large and medium-sized gold deposits in the shallow distributed along the regional fault might be integrated in a certain depth and often became a super large gold deposit.