Geochemical Characteristics And Genesis Of Copper Deposit In Yimenchang Copper Deposit, Yunnan Province

Tongchang copper deposit locates in the Yimen copper ore field east metallogenic belt of the KunYang rift, which is in southwest of Yangtze platform, Yunnan Province. It is one of the most representative ore deposit in the ore field. The thesis based on tutor’s program of the Enterprises and universities of "Study on the metallogenic regularity and predication of ore deposit of Tongchang or Periphery copper deposit (NO. KKK0201321099) ". Based on the analysis of the ore forming geological setting, geology characteristics, geochemical characteristics, and ore forming geological conditions of the deposit, the source of ore-forming materials, the ore-controlling factors, the genesis of deposit and etc are studied. Typical ore body of Tongchang copper deposit and ore-deposit geochemistry are the important research object in the thesis, The Main achievements are obtained as follows:1.This paper studies suggest that there are two major copper deposit mineralization type in Tongchang copper deposit:Tongchang style and Jianshan style, Or copper deposition and hydrothermal copper. Tongchang style layers along the stratigraphic distribution but Jianshan style copper layers are not controlled.2.Tongchang style copper layers along the stratigraphic distribution, and the ore bodies appears in bedded, near-bedded and lenticular shapes in the Kunyang group Luoxue formation. Ore mineral assemblage of Tongchang style is relatively simple, the major valuable metallic minerals is bornite and the minor is chalcopyrite. the size range of its particle is from 0.05mm to 0.25mm and most of them not enough 0.10mm. The ore has micorite-microcrystalline texture and bedding and seams structure. Jianshan style copper layers are not controlled by stratum and its ore bodies occur in more complex section of structures of Kunyang group Luoxue formation or Etouchang formation. Chalcopyrite is the main objective of ore mineral in Jianshan style and it has a relatively large particle size range 0.01mm-1.54mm, a big part of particle’s size range between 0.05-0.25mm,but which is greater than 0.25mm constitute a high proportion and even more, some particle’s size bigger than 1 mm. The ore texture includes metasomatic texture and separation of the solid solution texture and the structures mainly include fine stockwork structure and disseminated structure.3.The ratio of Co/Ni are between 0.51-1.74, and average value is 1.062 in Tongchang style copper, which shows the reason of deposition and diagenesis. Relevantly, it ran up to 2.65 and demonstrated hydrothermalism.4. Research of sulfur isotope geochemistry shows that Tongchang style copper had a origin of deposition and diagenesis, but Jianshan style copper originated abyssal sulfur recharge5.By researching the characteristics of the Pb isotope from Tongchang copper deposit, we recognized that the Jianshan style ore stemmed from the Magma of deep within the earth and has withstood the assimilation of crust. The ore forming fluids come from the magma mainly, mixed the later period substance of crust.6.The metallogenic material Tongchang type orebodies are mainly from strata, and affe cted by the late hydrothermal in a certain extent. Orebodies by strata, lithology and lithofacies palaeogeographic control, metallogenic epoch and the ore bearing strata formatio n time consistent; Orebodies by strata, lithology and lithofacies palaeogeographic control, m etallogenic epoch and the ore bearing strata formation time consistent; metallogenic material of Jianshan type orebody mainly comes from deep, orebodies are influenced by lithology and structure, metallogenic epoch is Jinning period.7. There are two major copper deposit mineralization type in Tongchang copper deposit, Witch is a metallogenetic model of copper deposition and hydrothermal superimposition copper.