大陆块体地球化学边界与成矿——兼论中国东秦岭金属矿集区的构造控制

THE GEOCHEMICAL BOUNDARY OF CONTINENTAL BLOCKS AND MINERALIZATION —An example from the mineral deposits concentrated area in east Qinling,China

地球块体不均一性边界存在地球化学急变带 ,控制大型矿床的分布 ;深部构造或隐性的构造面与地壳浅表形成的矿集区有明显的空间和形成机制耦合关系。地球化学急变带在大陆内部往往沿着一些古大陆边缘展布 ,与地壳下部和上地幔的深部构造或扩展到地幔的不连续面具有相联系的空间组合关系 ,反映壳幔相互作用对深部构造效应和大规模成矿热流体的控制。东秦岭金属矿化集中区的大型或超大型矿床沿古大陆边缘产出 ,并受地球化学急变带与地球物理梯度带交叉效应控制 ,揭示了深部构造对大型矿集区的制约。

Deep structures or conceal structural planes obviously have the coupling relationship with the convergent area of deposits.The geochemical steep\|dipping zone is usually distributed along the boundary of ancient continental block.Its crossing effect with geophysical gradient zone is usually presented as depression or swell of Moho discontinuity on the crossing direction with the ancient continental margin,which would lead to form deep fractures of earth crust at block margins or lead to adjustment of Earth crust texture.The deep hydrothermal liquid would rise up along the structural planes to form the convergent areas of mineral deposits.For example,Luonan—Luanchuan area in east Qinling is a typical crossed area of the geochemical steep\|dipping zone and geophysical gradient zone.The mineral deposit belt extends along E—W direction.It is controlled by the geochemical steep\|dipping zone at equidistantly,distributed along NE direction like a string of beads,controlled by a gravity gradient zone in NE direction and a mantle depression slope.Along a plunging mantle syncline on E—W plunging direction,from the east to the west are distributed check\|from fractures,controlling synergic crust\|mantle grano\|porphyry rocks at Luonan—Luanchuan area,occurring a convergent mineralization area of Mo,W,Zn and Au giant deposits.