高校地质学报2012，Vol.18Issue(2)：291-306,16.
秦岭早中生代壳幔岩浆混合作用——来自东江口花岗岩体闪长质包体的地球化学证据
Early Mesozoic Crust- and Mantle-Derived Magmatic Mixing in the Qinling Orogeny: Evidence From Geochemistry of Mafic Microgranular Enclaves in the Dongjiangkou Pluton
摘要
Abstract
The zircon U-Pb ages of 218 Ma and 224 Ma have been obtained from the Dongjiangkou granitoids and their mafic enclaves, respectively. The disequilibrium magmatic textures can be found in the mafic enclaves, which have some K-feldspars similar to those of host granitoids and needle-like apatite formed under a quenching condition, indicating a two-end member magmatic mixing in the early Mesozoic. The two-end member magmatic mixing resulted in similar geochemical compositions and strong homogenization of Sr-Nd-Pb isotopes between host granitoids and their mafic enclaves. However, Hf isotopic composition of the mafic enclaves shows a wide range of ΕHF(T) That varies from -4.58 to 3.31, registering the source features of two-end member magma. Thus, the positive εHf(t) values (> 10) of zircons from the contemporary mafic enclaves provide evidence that the mafic magma was derived from the depleted mantle. While, host granitoids with negative εHf(t) values (<10) of zircons were products of partial melting of the Mid-Proterozoic mantle-derived basic rocks. Since then, the distinct crust- and mantle-derived magmas were mixed around 224 Ma, resulting in a large number of granitic intrusions with abundant mafic enclaves during the early Mesozoic in the Qinling orogeny.关键词
早中生代/闪长质包体/岩石地球化学/壳幔岩浆混合作用Key words
Early Mesozoic/ mafic enclave/ petro-geochemistry/ crust-and mantle-derived magmatic mixing分类
天文与地球科学引用本文复制引用
李雷,张成立,周莹,田会全,李小菲..秦岭早中生代壳幔岩浆混合作用——来自东江口花岗岩体闪长质包体的地球化学证据[J].高校地质学报,2012,18(2):291-306,16.基金项目
国家自然科学基金重点项目(40830314) （40830314）
西北大学大陆动力学国家重点实验室科技部专项基金联合资助 （）
