Yanshanian magmatic hydrothermal superimposed mineralization in Jinkeng Sn-Cu polymetallic deposit,eastern Guangdong Province
The Jinkeng Sn-Cu polymetallic deposit is located in northeastern part of the Lianhuashan fault in Guang-dong Province.It has long been hotly debated about its genesis.Hydrothermal cryptoexplosive breccia is first dis-covered in Mashan ore section of Jinkeng Sn-Cu polymetallic deposit by core logging and petrographic observa-tion,and the hydrothermal activity can be divided into 5 stages in detail.On this basis,this paper carried out de-tailed zircon U-Pb dating of granitic breccia in hydrothermal cryptoexplosive breccia,and detailed in-situ sulfur isotope analysis of sulfide.The granite have zircon U-Pb age about 150 Ma,have εHf(t)values ranging from-8.20 to-4.55,and Hf model ages(TDM2)of 1.72～1.49 Ga,suggesting that the granite formed by the partial melting of Mesproterozoic crustal material,and contain a minor mantle-derived component.In-situ sulfur isotope analysis of sulfides show that there are obvious differencesed in sulfur isotopic composition of sulfides from different stages.Significantly,the sulfur isotope changes in pyrite of different stages before crushing(Py-Ⅰ:-0.65‰ to 1.11‰,n=5)and after deformation(Py-Ⅱ:1.30‰to 1.93‰,n=5),and the δ34S of chalcopyrite associated with Py-Ⅱis 1.42‰to 1.87‰(n=16).Chalcopyrite in the third stage have high δ34S values ranging from 3.69‰to 4.32‰(n=4),in which the δ34S value of chalcopyrite in cryptoexplosive breccia cement(Ccp-Ⅲa:3.69‰to 3.74‰),which is slightly lower than that in quartz-chlorite vein(Ccp-Ⅲb:4.29‰to 4.32‰).The pyrite from the fourth stage have lower δ34S value(Py-Ⅳ:-4.87‰,n=1;Ccp-Ⅳ:-3.07‰,n=1).Considering that the tin deposits in Jinkeng and its adjacent area are mainly formed in～144 Ma,while the copper deposit is formed in 170～150 Ma.It is considered that there are at least two magmatic and hydrothermal events in Jinkeng deposit,in which the granitic magmatic activity derived from crust-mantle mixing of～150 Ma may be an important magmatic event to trigger Cu mineraliza-tion in the mining area.This work could hopefully promote the Sn and Cu prospecting along Lianhuashan fault belt.
国家科技期刊平台
NSTL
万方数据
