河淮地幔亚热柱的演化及其对华北地区成矿的控制作用

The Formation of Hehuai Sub-mantle Plume and Its Controlling to the Mineralization in North China

本文依据华北地台东部的地球物理测深资料、火山－岩浆活动、沉积建造特征及构造演化历史，提出河滩地区是中生代以来强烈隆升的地幔亚热柱。亚热柱的强烈上升使岩石圈下部发生热减薄，上地壳发生裂陷，新生界堆积厚达５－９ｋｍ。岩石圈热减薄仅至６０－８０ｋｍ。金、银等成矿元素除部分来自赋矿围岩之外，其主要部分来自地核，并以气态随地幔热柱向上运移，当其进入亚热柱阶段时，部分转变为液态．呈气－液混合相随亚热柱运移，当伞状外展亚热柱被造山带陡倾韧性剪切带切割时，气－液相全、银随深熔岩浆或沿韧性剪切带向上迁移，并在幔枝（变质核杂岩）构造的有利扩容带富集成矿。

ased on the geophysical prospecting, volcanic-magmatic activities, sedimentary formation and structural evolution in eastern part of North China platform, it is proposed that Hehuai area has been an intensively uplifted submantle plume since the Mesozoic. Duo to the intensive uplifting of the submantle plume, the lower lithosphere was thinned and the .upper crust was down faulted. Cenozoic sediments are up to 5-9km thick. The lithosphere was only 60-80km thick.The uplifting submantle plume was blocked at the bottom of lithosphere. The mantle plume.changed into half-spherical (shaped like a umbrella) and extended towards the surroundings. This made the middle-lower crust form gently declined detachmenting flow deformation layer (low velocity layer). As the mantle-crust interface gradually increased to 100-160km towards the surrounding, inadequate gravity resulted in uplifting of the crust and formed orogenic zone along the margin of the submantle plume. Meanwhile, the sharply declined ductile shearing zone in the axis of the orogenic zone cut off gently declined crust-mantle detachmenting flow deformation zone,the depressure and unloading made the soften rocks form anatectic magyna. Anatectic magyna melted some country rocks and intruded along the ductile shearing zone, this speeded up the uplifting of orogenic zone and formed the third class tectonic unit of the montle plume-mantle branch structure. The cover was openly detachmented in the place of quickly uplifting area. meta-morphosed basement rocks were exposed to form typical metamorphic core complex.Mineralization elements (such as An and Ag) which mainly came from the core moved up as gas with the mantle plume. In the submantle environment, some gaseous mineralization elements changed into liquid and moved up as gas-liquid mixture. When the umbrella-like extended submantle plume was cut off by sharply declined ductile shearing zone in orogenic belt, gas-liquid Au and Ag immigrated up with the anatectic magma along the ductile shearing zone and concentrated in favorable place to form industry deposits in mantle branch structure (metamorphic core complex).