Zircon Trace Element Geochemistry of Yanshanian Biotite Granite from Longyuanba Complex in the Eastern Nanling Range and Its Geological Significance
In order to study the character of magmatic source materials and pegtrogenetic processes of the highly fractionated granites in Nanling range,the zircon trace elements are analyzed by LA-ICP-MS from the Yanshanian biotite granite in Longyuanba complex,eastern the Nanling range.The results indicate that zircon can be divided into two groups based on its trace element composition:the first group is zircon crystallized in a relatively early stage of magma evolution,without fine-grained inclusions such as apatite.The second group consists of zircons crystallized in a relatively late stage of magma evolution,containing a certain amount of fine-grained inclusions such as apatite.The magma crystallization temperature of the Yanshanian biotite granite in Longyuanba is 667～916 ℃,with an average of 761 ℃;The oxygen fugacity is lg f(O2)=-14.3～-12.5,the relative oxygen fu-gacity(△FMQ)is-1.4～0.3,and the average is-0.2.The magma underwent strong separation and crystalli-zation of minerals such as apatite,sphene,zircon,and plagioclase,ultimately forming a highly differentiated Ⅰ-type biotite granite.
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