An Early Cretaceous garnet-bearing metaluminous A-type granite intrusion in the East Qinling Orogen,central China:Petrological,mineralogical and geochemical constraints  

作　　者：Jinyang Zhang Changqian Ma Zhenbing She 

机构地区：[1]Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China [2]Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China [3]State Key Laboratory of Geological Processes and Mineral Resoureex, China University of Geosciences, Wuhan 430074, China

出　　处：《Geoscience Frontiers》2012年第5期635-646,共12页地学前缘（英文版）

基　　金：supported by the Key International S & T Cooperation Project(No.2007DFA21230) of the Ministry of Science and Technology;the Natural Science Foundation of China (No.40521001,40334037,and 40903017);Nature Science Foundation of Hubei Province(No.2009CDA004);the Ministry of Education of China and the State Administration of Foreign Expert Affairs of China(No.B07039)

摘　　要：The Erlangmiao granite intrusion is located in the eastern part of the East Qinling Orogen. The granite contains almost 99 vol.% felsic minerals with accessory garnet, muscovite, biotite, zircon, and Fe-Ti oxide. Garnet is the dominant accessory mineral, shows zoned texture, and is rich in w（FeO） （14.13%--16.09%） and w（MnO） （24.21%--27.44%）. The rocks have high SiO2, alkalis, FeOt/ MgO, TiO2/MgO and low A1203, CaO with w（Na2O）/w（K20）〉 ]. Their Rb, Ga, Ta, Nb, Y, and Yb contents are high and Sr, Ba, Eu, Zr, P, and Ti contents are low. These features indicate that the Erlang- miao granite is a highly evolved metaluminous A-type. Garnet crystallized at the expense of biotite from the MnO-rich evolved melt after fractionation of biotite, plagioclase, K-feldspar, zircon, apatite, and ilmenite. The relatively high initial 878r/S6Sr ratios （0.706--0.708）, low and negative εNd （120 Ma） values （-6.6 to -9.0）, and old Nd model ages （1.5--1.7 Ga） suggest that the rocks were probably formed by partial melting of the Paleoproterozoic granitic gneisses from the basement, with participation of depleted mantle in an extensional setting.The Erlangmiao granite intrusion is located in the eastern part of the East Qinling Orogen. The granite contains almost 99 vol.% felsic minerals with accessory garnet, muscovite, biotite, zircon, and Fe-Ti oxide. Garnet is the dominant accessory mineral, shows zoned texture, and is rich in w（FeO） （14.13%--16.09%） and w（MnO） （24.21%--27.44%）. The rocks have high SiO2, alkalis, FeOt/ MgO, TiO2/MgO and low A1203, CaO with w（Na2O）/w（K20）〉 ]. Their Rb, Ga, Ta, Nb, Y, and Yb contents are high and Sr, Ba, Eu, Zr, P, and Ti contents are low. These features indicate that the Erlang- miao granite is a highly evolved metaluminous A-type. Garnet crystallized at the expense of biotite from the MnO-rich evolved melt after fractionation of biotite, plagioclase, K-feldspar, zircon, apatite, and ilmenite. The relatively high initial 878r/S6Sr ratios （0.706--0.708）, low and negative εNd （120 Ma） values （-6.6 to -9.0）, and old Nd model ages （1.5--1.7 Ga） suggest that the rocks were probably formed by partial melting of the Paleoproterozoic granitic gneisses from the basement, with participation of depleted mantle in an extensional setting.

关 键 词：GARNET A-type granite Early Cretaceous East Qinling Orogen 

分 类 号：P588.121[天文地球—岩石学] P54[天文地球—地质学]