Late Mesozoic crust-mantle interaction and lower crust components in South China: A geochemical study of mafic granulite xenoliths from Cenozoic basalts

Science in China Series D: Earth Sciences - Tập 46 - Trang 447-460 - 2003
Jinhai Yu1, Xisheng Xu1, Xinmin Zhou1
1State Key Laboratory of Deposit Research, Department of Earth Sciences, Nanjing University, Nanjing, China

Tóm tắt

Mafic granulite xenoliths collected from Cenozoic basalts in SE China can be classified as magmatic granulite and cumulate granulite. Magmatic granulites are characterized by highly concentrated AI2O3, K2O, P2O5, Ba, Sr, Pb and REE, and low contents of Nb, Zr, Hf and Th, and have an incompatible element abundance pattern similar to that of continental arc basalts. Cumulate granulites are depleted in K2O, P2O5, Rb, Cs and Ba. These granulite xenoliths were the prod-ucts of crystallization and recrystallization of the basaltic magma underplating into crust-mantle boundary in Late Mesozoic. Sr and Nd isotopic compositions and variation trend of these mafic rocks are the result of crust-mantle mixing and controlled by assimilation and fractional crystallization process (AFC). However, trace element and major element variations were mainly controlled by fractional crystallization. The granulites are similar in geochemistry to surface Late Mesozoic gabbro and basalt in the study area, suggesting a close petrogenetic link between them. Late Mesozoic basaltic magma activities are the most important cause for the formation of extensive contemporaneous granite and rhyolite in the study area. This study and previous data indicate that the lower crust beneath South China is composed of a variety of Paleo- to Meso-proterozoic metamorphic rocks and Late Mesozoic mafic granulites.

Tài liệu tham khảo

Fan, Q. C., Liu, R. X., The high temperature granulite xenoliths in Hannuoba basalt, Chinese Science Bulletin, 1996, 41: 235–238.

Fan, Q. C, Liu, R. X., Li, H. et al., Zircon geochronology and rare earth element geochemistry of granulite xenoliths from Hannuoba, Chinese Science Bulletin, 1998, 43(18): 1510–1515.

Zhang, G., Zhou, X., Chen, S. et al., Five dimensional feature of Sr-Nd-Pb isotopic compositions of granulite and pyroxenite xenoliths from Hannuoba basalt: Geological implications, Chinese Science Bulletin, 1999, 44(7): 642–646.

Chen, S., O’Reilly, S. Y., Zhou, X. et al., Thermal and petrological structure of the lithosphere beneath Hannuoba, Sino-Korean Craton, China: Evidence from xenoliths, Lithos, 2001, 56: 267–301.

Xu, X., Zhou, X., The xenoliths from Qilin Cenozoic basaltic pipe, Guangdong Province, Acta Petrol. Sinica (in Chinese), 1995, 11(4): 441–448.

Tao, K., Xing, G., Wang, Q. et al., The study of mafic granulite xenolith from Xinchang, Zhejiang Province, Regional Geology of China (in Chinese), 2001, 20(3): 328–330.

Zhou, J., Zhang, H., Yu, Y., Magma mixing in Early Cretaceous composite lava flows in Xinchang, Zhejiang Province, Acta Petrol. Sinica (in Chinese), 1994, 10: 236–247.

Dong, C., Zhou, X., Li, H. et al., The Late Mesozoic crust-mantle interaction in southeast Fujian Province: Evidence from isotope compositions of Pingtan igneous complex, Chinese Science Bulletin, 1997, 42(6): 495–498.

Rudnick, R. L., McDonough, W. F., McCulloch, M. T. et al., Lower crustal xenoliths from Queensland, Australia: Evidence for deep crustal assimilation and fractionation of continental basalts, Geochim. Cosmochim. Acta, 1986, 50: 1099–1115.

Li, W., Zhou, X., Geochemical restriction on the petrogenesis of Late Mesozoic igneous rocks in the coastal region of Zhejiang and Fujian provinces, Progress in Natural Science (in Chinese), 2000, 10(7): 630–641.

Zhou, J., Chen, R., Qiu, J., Late Mesozoic crust-mantle interaction in the coastal region of SE China, in Origin of Late Mesozoic granitic volcanic and intrusive complex and crustal evolution in southeastern China (eds. Wang, D., Zhou, X. M.) (in Chinese), Beijing: Science Press, 2001, 116–143.

Sun, S. S., McDonough, W. F., Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes, in Magmatism in Ocean Basins (ededs. Saunders, A. D., Norry, M. J.), Geol. Soc. London, Spec. Publ., 1989, 42: 313–345.

Xie, D. K., Ma, R. S., Zhang, Y. et al., Continental Crust Creation and Plume Tectonics in South China (in Chinese), Beijing: Geology Press, 1996.

Hu, G., Zhang, B., Neodymium isotope composition and source materials of the meta-basement in central Jiangxi Province, Acta Petrol. etMin. (in Chinese), 1998, 17(1): 35–39.

Yu, J., Gui, X., Huang, L., Sr-Nd-O-H isotope compositions of Silun migmatite field in Luoding, Guangdong Province, Guangdong Geol. (in Chinese), 1991, 6(3): 73–82.

Yuan, Z., Wu, L., Zhang, Z. et al., The Sm-Nd, Rb-Sr isotopic age-dating of Mayuan Group in North Fujian, Acta Petrol. et Min. (in Chinese), 1991, 10(2): 127–132.

Yu, J. H., Shu, L. S., Metamorphism, Magmatism and tectonics in coastal region of Fujian Province, SE China, in Origin of Late Mesozoic Granitic Volcanic and Intrusive Complex and Crustal Evolution in Southeastern China (in Chinese) (eds. Wang, D., Zhou, X.), Beijing: Science Press, 2002, 40–68.

Xu, X., Zhou, X., O’Reilly, S. Y. et al., Exploration for the lower crustal material and granite genesis in Southeastern China, Acta Petrol. Sinica (in Chinese), 1999, 15: 217–223.

Zindler, A., Hart, S. R., Chemical geodynamics, Ann. Rev. Earth Plant. Sci., 1986, 14: 493–571.

Depaolo, D. J., Trace element and isotopic effects of combined wallrock assimilation and fractional crystallization, Earth Plant. Sci. Lett., 1981, 53: 189–202.

Lesher, C. E., Decoupling of chemical and isotopic exchange during magma mixing, Nature, 1990, 344: 235–237.

Hu, S., Xu, J., Tong, Z. et al., Precambrian Geology in Southwest Zhejiang Province (in Chinese), Beijing: Geology Press, 1991.

Gan, X., Li, H., Sun, D. et al., Geochronological study on the Precambrian metamorphic basement in North Fujian, Geology of Fujian (in Chinese), 1993, 12(1): 17–31.

Gan, X., Zhao, F., Jin, W. et al., The U-Pb ages of Early Proterozoic-Archean zircons captured by igneous rocks in South China, Geochimica (in Chinese), 1996, 25(2): 112–119.