Jinping Nickel-copper Deposit Mechanism

In recent years , a series of significant and new undstandings have been achieved following the basic geological researchs including: the important fundamental study on the constitution-lava-transformation strip, the geological evolution process, the minerogenetic effection and the minergenetic series. These achievements are favorable for further study on metallogenesis of basic-ultrabasic mixed rock strip in Jinping, Yunnan Province.This paper is mainly focused on profound discussion on metallogenetic mechanics of Jinping nickel-copper ore deposit. The rock mass III (ore contained) is especially concerned. Based on petrography, we hope to obtain the intrusion mode and time. From the tectonics (especially faults) of this deposit area, we hope to illustrate how regional faults control the spreading mode of intrusion tunnel for rock belt and rock mass. Based on systematic analysis of constant and minor elemental characteristics in all the petrography belts (including ore body), we hope to study the evolution process of each petrography belts (including ore body). We also wanted to find out the self-alteration--geochemistry evolution process and the rock mass and ore body how to surffer the reformation of tectonic effection and the subsequent hydrothermal superimposed metamorphism.According to our investigation on rock mass Ⅲ in Jinping nickel-copper ore deposit, some results as follows were obtained.l.The intrusion period of rock mass-ore body was analysised. Based on integrated analysis, isochronal 1 ine age of Re-Os isotopes of Baimazhai nickel-copper sulfides is 249 Ma. Thus we considered that the intrusion period of Baimazhai basic-ultrabasic rock is in late Hercynian.2.Constant, minor and rare earth elements in each petrography belt and ore body were systematically analysed. According to which the rock mass-ore body evolution process were considered to be trans-evolution sequences: gabbro-augite peridotite-peridotite-ore body.3.Systematic analysises was carried out on the characteristics of protogenetic self-alteration and the subsequent hydrothermal superimposed metamorphism of the rock mass and ore body. The result showned that the gas-liquid fluid, produced by crystallization differentiation of basic-superbasic lava of Baimazhai diamictite, have eroded the premature olivine and augite, leading to self-alteration. Furthermore, in later geological evolution, such rock mass have endured extra carbonation and talcumation.4.Faults control factors were systematically analysed. We determined that the rock belt and the rock mass of the research area has endured intensive nappe process. The ore body now is not situated in initial intrusion site.5. The reformation of superimposition after intrusion of rock mass and ore body was investigated. The result showed that after intrusion of lava, vast scale reformation of superimposition has also happened in Himalayan Period.Totally speaking, this research is valuable in basic and economic geological research.