摘要
东秦岭钼成矿带呈近东西向沿华北大陆南缘地球化学边界展布 ,矿化表现为等间距北东向成串产出。在洛南—栾川地区深部是一个轴向近东西向且向西倾伏的幔向斜 ,其走向控制了华北块体南缘地球化学边界。沿北北东向的重力梯度带方向上 ,刚性的结晶基底发生隐性的构造破裂组合或不均匀调整作用。它们与古大陆边缘相平行的深断裂束互相叠加 ,形成格子状分布的深断裂组合 ,控制了壳幔同熔型花岗岩浆的侵位 ,形成一系列中酸性小岩体。含矿岩石类型主要有花岗斑岩、石英二长岩 ,构成了巨量的钼、钨、锌、铜、金矿化集中区。成矿地质背景和同位素年龄表明 ,控岩控矿构造与岩浆活动发生在燕山期 。
The porphyry type molybdenum ore belt in east Qinling measures more than 200km long and 20km wide,forming a NWW trending rectangle. Mineralizations are equidistantly distributed along NE direction like a string of beads. It is a typical crossed area of the geochemical steep dipping zone and geophysical gradient zone. Along a plunging mantle syncline in E W plunging direction and from the east to the west are distributed check shaped fractures which control the synergic crust mantle grano porphyry rocks in the Luonan luanchuan area. Our preliminary interpretation is as follows: The Luonan Luanchuan area at depth was a westward plunging mantle syncline with a nearly E W axis direction. The geochemical boundary was controlled by the strike direction of syncline. The geophysical gradient zone was controlled by the steep slope of the syncline. Their crossing effect caused the structural fracture assembly on the NNE direction along the rigid block margin. These superimposed upon parallel fracture bunches on the ancient continental margin, which were expressed as the check shaped distribution pattern. Under the influence of crust mantle interaction the fluid moved up along the structures to the shallower crust and formed mineral deposits. There occurs a series of small masses of early and late Yanshanian granite porphyries,diorite and various dyke rocks of acid intermediate compositions. The main controlling factors of this porphyry molybdenum ore belt were dependent on the character of magmatic activities and conditions of occurrences. The molybdenum mineralization was closely related to the highly acidic, alkali and potash rich Yanshanian small intrusive bodies. Both the rock forming and ore forming processes are structurally controlled in time and space.
出处
《高校地质学报》
CAS
CSCD
2001年第3期307-315,共9页
Geological Journal of China Universities
基金
国家自然科学基金 (编号 40 0 72 0 33)
国家科技部 973项目 (编号 :G19990 432 13)
郑州大学科研基金资助
