The Geochemical Studies On Copper Polymetallic Deposits Of Middle-southern Part Of Lancangjiang, Yunnan Province, China

The Lancangjiang river is located in the west of Yunnan province and the southeast of Qingzang plateau. Seen from the structure,this district belongs to the structure region of Tethys-Himalayas,"Sanjiang" fold system,and the fracture-fold zone of Lancangjiang river.The geological structure of this area is complex and the types of the copper (polymetallic) deposits are plentiful. This paper draws conclusions from the studies on five typical deposits which are distributed in the west of Lanping-Simao basin. These conclusions are as follows:the types of copper deposits are different because the geological backgrounds of this area in different period are different;Songjiapo copper deposit belongs to a typical porphyry deposit,its mineral liquid mainly come from the magma that formed the Triassic eruptive rocks and effected by the subsequent geological action;Jinman copper deposit,Shuixie copper deposit and Kedengjian copper deposit are the hydrothermal type. Their mineralization liquids mainly come from the deep of the earth's crust or from the earth's mantle,and their mineralizations are constrained by fracture structure,the deposits mainly formed in Himalayanism;but the Dapingzhang deposit is a typical volcanic hosted massive sulfide deposits and its mineralization is manipulated by the Carboniferous eruptive magmatism.This paper makes systematic studies on geochemical characteristics and the geological background. To give a theoretical evidence to better explore and exploit these copper resources in this area,this paper elementarily analyses the mechanic of mineralization and put forward a model of mineralization.