1 Introduction Sanjiang tectonic-magma belt is one of the most potential resources’metallogenic belts in China.Cenozoic alkali-rich porphyry-type gold polymetallic mineralization system is a significant characteristi...1 Introduction Sanjiang tectonic-magma belt is one of the most potential resources’metallogenic belts in China.Cenozoic alkali-rich porphyry-type gold polymetallic mineralization system is a significant characteristic of thisbelt.Chenghai-Binchuan tectonic belt,located in the western margin of the Yangtze block,is an important part展开更多
The authors studied the geochemistry, zircon U-Pb ages, Hf isotope of the granite porphyry and its petrogenesis and tectonic setting in the studied area. The zircon U-Pb dating indicates the formation of the granite p...The authors studied the geochemistry, zircon U-Pb ages, Hf isotope of the granite porphyry and its petrogenesis and tectonic setting in the studied area. The zircon U-Pb dating indicates the formation of the granite porphyry is in Early Cretaceous （ 125.1 ± 1.5 Ma）. The granite porphyry has high-SiO2 and alkali-rich features, which belongs to high-K talc-alkaline series rocks （ A/CNK = 0. 95%-1. 25% ）. The analyses of trace elements show the characteristics of a swallow-shaped REE distribution pattern with enrichment in LREEs and most of LILEs and HFSEs, depletion in Ba, Sr, Nb, P and Ti, and especially strong depletion in Eu, which indicates the granite porphyry belongs to the aluminous A-type granite. Their εHf（t） range from 5.94 to 8.80 with Hf two-stage model ages （TDM2 ） of 620 Ma to 803 Ma. Combining with the regional tectonic background, we conclude that the source of the rocks is the new crust materials accreted from depleted mantle in Neoproterozoic and is the product of partial melting of middle and lower crustal rocks, which may be suffered from the dual impact of the subduction of the Palaeo-Pacific Ocean and the closure of the Mongol-Okhotsk Ocean.展开更多
The characteristics of the chemical composition of the richalkali granite porphyries are poor in SiO2, with mean content of 6919%, but rich in alkali and high in potash. The mean content of (K2O+Na2O) is 985%. K2O is ...The characteristics of the chemical composition of the richalkali granite porphyries are poor in SiO2, with mean content of 6919%, but rich in alkali and high in potash. The mean content of (K2O+Na2O) is 985%. K2O is much greater than Na2O, mean value of K2O/Na2O is 210. As shown by the REE analysis, REE contents is lower. Compared with the granite of south China, the richalkali granite porphyry hase higher LREE, and no anomaly of europium (δEu=087). Its genetic type belongs to A type graritoid.展开更多
基金financially supported by the geological survey program of China Geological Survey(1212011120607)the basic research program of Yunnan Nonferrous Metals Geological Bureau(20131300001)
文摘1 Introduction Sanjiang tectonic-magma belt is one of the most potential resources’metallogenic belts in China.Cenozoic alkali-rich porphyry-type gold polymetallic mineralization system is a significant characteristic of thisbelt.Chenghai-Binchuan tectonic belt,located in the western margin of the Yangtze block,is an important part
文摘The authors studied the geochemistry, zircon U-Pb ages, Hf isotope of the granite porphyry and its petrogenesis and tectonic setting in the studied area. The zircon U-Pb dating indicates the formation of the granite porphyry is in Early Cretaceous （ 125.1 ± 1.5 Ma）. The granite porphyry has high-SiO2 and alkali-rich features, which belongs to high-K talc-alkaline series rocks （ A/CNK = 0. 95%-1. 25% ）. The analyses of trace elements show the characteristics of a swallow-shaped REE distribution pattern with enrichment in LREEs and most of LILEs and HFSEs, depletion in Ba, Sr, Nb, P and Ti, and especially strong depletion in Eu, which indicates the granite porphyry belongs to the aluminous A-type granite. Their εHf（t） range from 5.94 to 8.80 with Hf two-stage model ages （TDM2 ） of 620 Ma to 803 Ma. Combining with the regional tectonic background, we conclude that the source of the rocks is the new crust materials accreted from depleted mantle in Neoproterozoic and is the product of partial melting of middle and lower crustal rocks, which may be suffered from the dual impact of the subduction of the Palaeo-Pacific Ocean and the closure of the Mongol-Okhotsk Ocean.
文摘The characteristics of the chemical composition of the richalkali granite porphyries are poor in SiO2, with mean content of 6919%, but rich in alkali and high in potash. The mean content of (K2O+Na2O) is 985%. K2O is much greater than Na2O, mean value of K2O/Na2O is 210. As shown by the REE analysis, REE contents is lower. Compared with the granite of south China, the richalkali granite porphyry hase higher LREE, and no anomaly of europium (δEu=087). Its genetic type belongs to A type graritoid.
