摘要
The alkali-rich rocks, spreading along the suture zone of Jingsha River, refer to the alkali-rich porphyry rocks, which emplace during the Himalaya epoch in northwest of Yunnan Province, and consist of syenit, syenit porphyry, monzonite porphyry and granite porphyry. Petrological chemical analysis results suggest that silica is poor and aluminum is rich, and high potassium large ion lithophile elements （LILE）, light rare earth element （LREE） and Sr are obviously detracted in these rocks. High field strength elements （HFSE） and heavy rare earth element （HREE） are depleted, especially Nb, Ta, P and Ti. 8Eu： 0.09--1.64 shows that plagioclase does not appear fractional crystallization during the formation of alkali-rich rocks, t^348, H and O isotopes and Pb isotopes suggest that ore-forming fluid is derived from the mantle, and Pb is possibly mixed by mantle, wall rock and crust. The age of Pb in alkali-rich rocks is about 250-220 Ma. The age of alkali porphyry rock （dykes） varies from 30 Ma to 50 Ma. Alkali rocks have strong metallogenetic relation. Au mineralization is associated to the alkali magrnatic activities with a relatively high temperature, low pressure and high oxygen fugacity. However, copper mineralization is mainly associated with alkali-sub-alkali magmatic activities in a process of relatively low temperature, high pressure and lower oxygen fugacity.
The alkali-rich rocks,spreading along the suture zone of Jingsha River,refer to the alkali-rich porphyry rocks,which emplace during the Himalaya epoch in northwest of Yunnan Province,and consist of syenit,syenit porphyry,monzonite porphyry and granite porphyry.Petrological chemical analysis results suggest that silica is poor and aluminum is rich,and high potassium large ion lithophile elements(LILE),light rare earth element(LREE) and Sr are obviously detracted in these rocks.High field strength elements(HFSE) and heavy rare earth element(HREE) are depleted,especially Nb,Ta,P and Ti.δEu:0.09-1.64 shows that plagioclase does not appear fractional crystallization during the formation of alkali-rich rocks.δ34S,H and O isotopes and Pb isotopes suggest that ore-forming fluid is derived from the mantle,and Pb is possibly mixed by mantle,wall rock and crust.The age of Pb in alkali-rich rocks is about 250-220 Ma.The age of alkali porphyry rock(dykes) varies from 30 Ma to 50 Ma.Alkali rocks have strong metallogenetic relation.Au mineralization is associated to the alkali magmatic activities with a relatively high temperature,low pressure and high oxygen fugacity.However,copper mineralization is mainly associated with alkali-sub-alkali magmatic activities in a process of relatively low temperature,high pressure and lower oxygen fugacity.
基金
Project(1343-74334000019) supported by the PhD Innovation Subject of Central south University,China
Project(1960-71131100088 (CX2010B085)) supported by the Hunan Provincial Innovation Foundation For Postgraduate Students,China
