Crust evolution in Southeast China: evidence from Nd model ages of granitoids
Tóm tắt
Nd isotopic compositions of 58 granitoids in South China have been reported in this paper. These data together with other published data reveal that granites with Nd model ages(tDM) greater than 1.8 Ga are distributed mainly in three areas: southwestern Zhejiang-northwestern Fujian, two sides of the Wuyi Mountain and Wanyangshan-Zhuguangshan. These granites are believed to be derived from partial melting of old crust in these areas. The Mesozoic granites withtDM < 1.6 Ga are distributed in three zones: the Gangang structural zone, Nanling latitudinal structural zone and Fujian-Zhejiang coastal zone. These zones may have been an extensional tectonic setting and mantle-derived components or magmas may have been involved to different extents in the granite formation. Based on Nd model ages of granites and published chronological data of mafic and ultramafic rocks, it is believed that the crust in South China experienced episodic accretions, among which the early-middle Proterozoic is the most important period of crustal accretion.
Tài liệu tham khảo
Holmden, C., Dickin, A. P., Paleoproterozoic crustal history of the southwestern Grenville Province: evidence from Nd isotopic mapping, Can. J. Earth. Sci., 1995, 32: 472.
Chen, J. F., Nd, Sr, Pb isotope tracer and continental crust evolution of SE China, in Chemical Geodynamics ((ed. Zheng, Y. F.) (in Chinese), Beijing: Science Press, 1999.
Wang, Y. X., Zhao, Z. H., Bao, Z. W. et al., Geochemistry of granitoids from Zhejiang Province and crustal evolution— II. Proterozoic granitoids, Geochimica (in Chinese), 1997, 26(6): 57.
Shen, W. Z., Xu, S. J., Wang, R. C. et al., Isotopic geochemical characteristics of Jinning period granitoids around the Yangtze plate, in Chemical Geodynamics ((ed. Zheng, Y. F.) (in Chinese), Beijing; Science Press, 1999.
Huang, X., DePaolo, D. J., Study of sources of Paleozoic granitoids and the basement of South China by means of Nd-Sr isotope, Acta Petrologica Sinica (in Chinese), 1989, 5(1): 28.
Wang, Y. X., Zhao, Z. H., Bao, Z. W. et al., Geochenistry of granitoids from Zhejiang Province and crustal evolution—I Phanerozoic granitoids, Geochimica (in Chinese), 1997, 26(5): 1.
Zhu, B. Q., Theory and Application of Isotope System in Earth Science (in Chinese), Beijing: Science Press, 1998.
Gan, X. C., Zhao, F. Q., Jin, W. S. et al., The U-Pb ages of Early Proterozoic-Archean zircon captured by igneous rocks in South China, Geochimica (in Chinese), 1996,25(2): 112.
Shen, W. Z., Zhu, J. C., Liu, C. S. et al., Age of formation of Southeast China continental crust: the Nd isotopic model age evidence, J. Nanjing University Earth Sciences, in Chinese), 1989, (3): 82.
Jin, W. S., Sun, D. Z., Deep Crustal Structure of South China and its Evolution (in Chinese), Beijing: Geological Publishing House, 1997.
Hu, X. J., Xu, J. K., Tong, Z. X. et al., The Precambrian Geology of Southwestern Zhejiang Province, Precambrian Geology (in Chinese), Beijing: Geological Publishing House, 1991.
Fu, S. C., Chen, J. M., Lin, W. S., Geological characteristics of Upper Archaeozoic Tianjingping Formation (Arzt) in western Jianning, Fujian Province, Geology of Fujian (in Chinese), 1991, 10(2): 103.
Fu, S. C., Zhang, K. G., Geological characteristics of Late Archean metamorphic rocks in the Qiuyuan area of Pucheng Couny, Fujian Province, Geology of Fujian (in Chinese), 1994, 13(3): 193.
Li, X. H., Timing of the Cathaysia Block formation: constraints from SHRIMP U-Pb zircon geochronology, Episode, 1997, 20(3): 188.
Yuan, Z. X., Zhang, Z. Q., Sm-Nd isotopic characteristics of granitoids in the Nanling region and their petrogenetic analysis, Geological Review (in Chinese), 1992, 38(1): 1.
Deng, J. R., Zhang, Z. P., Gan-Hang tectonic zone and its geological significance, Uranium Geology (in Chinese), 1989, 5(1): 15.
Liu, C. S., Zhu, J. C., Shen, W. Z. et al., Classification and source materials of continental crust transformation series granitoid in South China, Acta Geologica Sinica (in Chinese), 1990, 64(1): 43.
Chen, J. F., Zhou, T. X., Li, X. M. et al., Sr-Nd isotopic composition of Mesozoic igneous rocks from southeastern China and its tectonic sginificance, in Studies of Structure and Evolution of the Continental and Oceanic Lithosphere of SE China ((ed. Li, J. L.) (in Chinese), Beijing: China Sci. Technol. Publ. House, 1992, 119–130.
Ling, H. F., Shen, W. Z., Huang, X. L., Nd-Sr isotopic composition of granitoids of Fujian and their significance, Acta Geologica Sinica, in press.
He, B. C., Liu, C. S., Zhu, J. C., Discussions on the age and source materials of tin-bearing granites, western side of Wuyi Mountain, J. Nanjing University (Earth Science, in Chinese), 1990, (1): 53.