| 湘东宏夏桥和板杉铺岩体LA-MC-ICPMS锆石U-Pb年龄及地质意义 |
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| 关键词:Hongxiaqiao Banshanpu zircon U-Pb South China Paleozoic intracontinental orogeny |
| 基金项目:中国地质科学院地质力学研究所基本科研业务费项目(编号: DZLXJK201403);中国地质调查局地质调查项目“华南深部结构探测” (编号: 12120114067801);国家专项“深部探测技术与实验研究”(编号: SinoProbe-08-01) |
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| LA-MC-ICPMS Zircon U-Pb Geochronology of the Hongxiaqiao and Banshanpu Granitoids in Eastern Hunan Province and Its Geological Implications |
| Internal structures and crystallization ages of zircons from the Hongxiaqiao and Bashanpu granitoids were analyzed using the CL technology and the LA-MC-ICPMS zircon U-Pb method, and the results show that the Hongxiaqiao granodiorite and Banshanpu monzonitic granite yield U-Pb zircon ages of 423~421 Ma and 422~421 Ma, respectively. Reliable geochemical data suggest that the two granitoids are metaluminous to peraluminous and share geochemical characteristics of typical adakitic rock, as expressed by high Sr/Y and La/Yb ratios and negative εNd(t) ratios, implying that they might have originated from partial melting of the thickened crust of South China during the Early Paleozoic period. Our geochronoglcial data, coupled with available isotopic ages related to regional magmatism and metamorphism, suggest that two stages of tectono-thermal events feature the Early Paleozoic intracontinental orogeny within South China. The earlier compressional event occurred at ca. 460~420 Ma and was characterized by widespread folding of pre-Devonian strata, crustal thickening and anatexis, migmatization and high-grade metamorphism. The later extensional event occurred at ca. 420~385 Ma and was characterized by the generation of post-orogenic granites as well as locally distributed transitional shearing and retrograde metamorphism. |
| LI Jian-hua,ZHANG Yue-qiao,ZHANG Yue-qiao,MA Zhi-li,LI Yong.2015.LA-MC-ICPMS Zircon U-Pb Geochronology of the Hongxiaqiao and Banshanpu Granitoids in Eastern Hunan Province and Its Geological Implications[J].Acta Geoscientica Sinica,36(2):187-196. |
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