Chinese Science Bulletin

, 47:259 | Cite as

Post-collisional lithosphere delamination of the Dabie-Sulu orogen

Discussion

Abstract

The consistence between the first rapid cooling time (226–219 Ma) of the untrahigh pressure metamorphic (UHPM) rocks in the Dabie Mountains and the formation time (205–220 Ma) of the syncollisional granites in the Qinling and Sulu areas suggests that the first rapid cooling and uplift of the UHPM rocks may be related to breakoff of subducted plate. Therefore the second rapid cooling and uplift (180–170 Ma) of the UHPM racks needs a post-collisional lithosphere delamination which resulted in the granitic magmatism with an age of about 170 Ma. In addition, the rapid rising of the Dabie dome in the early Cretaceous (130–110 Ma) and the corresponding large-scale magmatism in the Dabie Mountains need another lithosphere delamination. The geochronology of the post-collisional mafic-ultramafic intrusions and geological relationship between the mafic-ultramafic intrusions and granites suggest that partial melting was initiated in the mantle, and then progressively developed in the crust, suggesting a mantle upwelling underneath the Dabie Mountains. The unusual fractional trend of the gabbros characterized by lower SiO2 content (46.24%) corresponding to lower MgO content (4.53%) and their typical geochemistry features of the lower crust suggest underplating of the mantle derived magma and interaction between the magma and lower crust before their intrusion. Lithosphere delamination could be the dynamic cause of the mantle upwelling and underplating. The seismic tomography results of the Dabie Mountains and adjacent areas clearly show lithosphere thinning below the north and south sides of the Dabie Mountains. Because there is no Cenozoic magma event in the Dabie Mountains, the lithosphere thinning may result from delamination of thickened lithosphere mantle after collision. In addition, both the lower velocity zone in the 40 km depth and the basin + dome + basin coupling relationship in the Dabie Mountains also suggest the lithosphere delamination and underplating on the two sides of the orogen.

Keywords

lithosphere delamination post-collisional magmatism seismic tomography Dabie-Sulu orogen mantle upwelling and underplating 

References

  1. 1.
    Kay, R. W., Kay, S. M., Delamination and delamination magmatism, Tectonophysics, 1993, 219: 177.CrossRefGoogle Scholar
  2. 2.
    Gao, S., Zhang, B.-R., Jin, Z.-M. et al., How mafic is the lower continental crust? Earth Planet. Sci. Lett., 1998, 161: 101.CrossRefGoogle Scholar
  3. 3.
    Wu, F.-Y., Sun, D.-Y., Zhang, G.-L. et al., Deep Geodynamics of Yanshan Movement, Geol. J. China. Univ. (in Chinese), 2000, 6(3): 379.Google Scholar
  4. 4.
    Li, S.-G., Jagoutz, E., Chen, Y.-Z., Sm-Nd and Rb-Sr isotopic chronology and cooling history of ultrahigh pressure metamorphic rocks and their country rocks at Shuanghe in the Dabie Mountains, central China, Geochim. Cosmochim. Acta, 2000, 64: 1077.CrossRefGoogle Scholar
  5. 5.
    Li, S.-G., Xiao, Y.-L. et al., Collision of the North China and Yangtze Blocks and formation of coesite-bearing eclogites: Timing and processes, Chem. Geol., 1993, 109: 89.CrossRefGoogle Scholar
  6. 6.
    Li, S.-G., Wang, S.-S., Chen, Y.-Z. et al., Excess argon in phengite from eclogite: Evidence from dating of eclogite minerals by Sm-Nd, Rb-Sr and 40Ar/39Ar methods, Chem. Geol., 1994, 112: 343.CrossRefGoogle Scholar
  7. 7.
    Li, S.-G., Li, H.-M., Chen, Y.-Z. et al., Chronology of ultrahigh-pressure metamorphism in the Dabie-Sulu belt—II. Zircon U-Pb isotopic system, Sci. in China, Ser. D (in Chinese), 1997, 27(3): 200.Google Scholar
  8. 8.
    Ames, L., Tilton, G. R., Zhou, G., Geochronology and isotopic character of ultrahigh-pressure metamorphism with implications for collision of the Sino-Korean and Yangtze cratons, central China, Tectonics, 1996, 15: 472.CrossRefGoogle Scholar
  9. 9.
    Chavagnac, V., Jahn, B.-M., Coesite-bearing eclogites from the Bixiling complex, Dabie Mountains, China: Sm-Nd ages, geochemical characteristics and tectonics implications, Chem. Geol., 1996, 133: 29.CrossRefGoogle Scholar
  10. 10.
    Hacker, B.R., Ratschbacher, L., Webb, L. et al., U/Pb zircon ages constrain the architecture of the ultrahigh-pressure Qinling-Dabie Orogen, China. Earth Planet. Sci. Lett., 1998, 161: 215.CrossRefGoogle Scholar
  11. 11.
    Zhang, B.-R., Luo, T.-C., Gao, S. et al., Geochemical Study of the Lithosphere, Tectonics and Metallogenesis in the Qinling-Dabieshan Region (in Chinese), Wuhan: Press of China Univ. of Geosciences, 1994, 110–123.Google Scholar
  12. 12.
    Sun, W.-D., Li, S.-G., Chen, Y.-D. et al., Zircon U-Pb dating of grantoids from South Qinling, central China and their geological significance, Geochimica (in Chinese), 2000, 29(3): 209.Google Scholar
  13. 13.
    Lu, X.-X., Wei, X.-D., Xiao, Q.-H. et al., Geochronological studies of repakivi granites in Qinling and its geological implications, Geol. J. China Univ. (in Chinese), 1999, 5(4): 372.Google Scholar
  14. 14.
    Davies, J. H., Blanchenburg, F. V., Slab breakoff: A model of lithosphere detachment and its test in the magmatism and deformation of collisional orogens, Earth Planet. Sci. Lett., 1995, 129: 85.CrossRefGoogle Scholar
  15. 15.
    Zhong, Z. Q., Suo, S.-T., You, Z.-D., Regional-Scale Extensional Tectonic Pattern of ultrahigh-pressure and Highpressure metamorphic belts from the Dabie Massif, China, in Ultrahigh-Pressure Metamorphism and Geodynamics in Collision-type Orogenic Belt: Final Report of the Task Group III-6 of the International Lithosphere Project (eds. Ernst, W. G., Liou, J. G.), Columbia: Bellwether Publishing Ltd., 2000, 161–169.Google Scholar
  16. 16.
    Hacker, B. R., Ratschbacher, L., Webb, L. et al., What brought them up? Exhumation of the Dabie Shan ultrahigh-pressure rocks, Geology, 1995, 23: 743.CrossRefGoogle Scholar
  17. 17.
    Wang, G.-C., Yang, W.-R., Structure and chronological evidence of the Luotian dome in the core of the eastern Dabie Mountains, central China, Earth Sci. (in Chinese), 1996, 21(5): 524.Google Scholar
  18. 18.
    Sang, L-K., Wang, R.-J., Zhang, Z.-M. et al., Late Yanshanian granites in the Jiuzihe-Tiantangzhai area and uplift of the core of the Dabie orogenic belt, Acta Geol. Sinica (in Chinese), 2000, 24(3): 234246.Google Scholar
  19. 19.
    Chen, J., Xie, Z., Liu, S. et al., Cooling age of Dabie orogen, China, determined by 40Ar-39Ar and fission track techniques, Sci. in China, Ser. D, 1995, 38(6): 749.Google Scholar
  20. 20.
    Liou, Y.-S., Lo, C.-H., Tsai, C.-H. et al., Thermochronological study of the Dabie Shan ultrahigh-pressure metamorphic terrane, east central China, J. of Geol. Soc. China, 1999, 42(2): 159.Google Scholar
  21. 21.
    Ma, C.Q., Li, Z.C., Ehlers, C. et al., A post-collisional magmatic plumbing system: Mesozoic granitoid plutons from the Dabieshan high-pressure and ultrahigh-pressure metamorphic zone, eastcentral China, Lithos., 1998, 45: 431.CrossRefGoogle Scholar
  22. 22.
    Wei, C.-J., Zhang, L.-F, Wang, S.-H., The Mesozoic high-K granitoids in the eastern Dabie Mountains and its geological implications, Sci. in China, Ser D (in Chinese), 2000, 30(4): 355.Google Scholar
  23. 23.
    Chen, T.-Y., Niu, B.-G., Fu, Y.-L. et al., Geochronology of Yanshanian magmatism and metamorphism in the hinterland of the Dabie Mountains and their geological significance., Acta Geol. Sinica (in Chinese), 1991, 65: 329.Google Scholar
  24. 24.
    Xue, F., Rowley, D. B., Tucker, R. D., et al., U/Pb zircon ages of granitoid rocks in the North Dabie complex, eastern Dabie Shan, China, J. of Geology, 1997, 105: 744.CrossRefGoogle Scholar
  25. 25.
    Wang, D.-Z., Ren, Q.-J., Qiou, J.-S. et al., Geological and geochemical characteristics of shoshonite series in eastern China and mineralization, Acta Geol. Sinica (in Chinese), 1999, 70: 23.Google Scholar
  26. 26.
    Li, S-G., Hong, J.-A., Li, H.-M. et al., U-Pb zircon ages of the pyroxenite-gabbro intrusions in Dabie Mountains and their geological implications, Geol. J. China Univ (in Chinese), 1999, 5(3): 345.Google Scholar
  27. 27.
    Ge, N.-J., Hou, Z.-H., Li, H.-M. et al., U-Pb zircon age of the mafic-ultramafic rocks from the Shacun, Yuexi area in the Dabie Mountains, Chinese Sci. Bull (in Chinese), 1999, 44(19): 2110.Google Scholar
  28. 28.
    Li, S-G., Nie, Y.-H., Liu, D.-L. et al., Interaction between subducted comtinental crust and the mantle—I. Major and trace element geochemistry of the syncollisional mafic-ultramafic intrusions in the Dabie Mountains, Sci. in China, Ser. D, 1998, 41: 545.CrossRefGoogle Scholar
  29. 29.
    Li, S.-G., Nie, Y.-H., Hart, S.R. et al., Interaction between subduted continental crust and the mantle—I. Sr and Nd isotopic geochemistry of the syncollisional mafic-ultramafic intrusions in the Dabie Mountains, Sci. in China, Ser. D, 1998, 41(6): 632.CrossRefGoogle Scholar
  30. 30.
    Jahn, B.-M., Wu, F.-Y., Lo, C.-H. et al., Crust-mantle interaction induced by deep subduction of the continental crust: geochemical and Sr-Nd isotopic evidence from post-collisional mafic-ultramafic intrusions of the northern Dabie complex, central China, Chem. Geol., 1999, 157: 119.CrossRefGoogle Scholar
  31. 31.
    Xu, P.-F., Sun, R.-M., Liu, F.-T. et al., Seismic tomography showing subduction and slab breakoff of the Yangtze block beneath the Dabie-Sulu orogenic belt, Chinese Sci. Bull., 2000, 45, 70–73.CrossRefGoogle Scholar
  32. 32.
    Anhui Bureau of Geology ad Mineral Resources, Regional Geology of Anhui Province (in Chinese), Beijing: Geol. Publ. House, 1987, 382–394.Google Scholar
  33. 33.
    Li, Z. X., Collision between the North and South China blocks: A crustal-detachment model for suturing in the region east of the Tanlu fault, Geology, 1994, 22: 739.CrossRefGoogle Scholar
  34. 34.
    Chung, S.-L., Trace element and isotope characteristics of Cenozoic basalts Around the Tanlu Fault with implications for the eastern plate boundary between North and South China, J. Geol., 1999, 107: 301.CrossRefGoogle Scholar
  35. 35.
    Hopper, J.R. and Buck, W.R. Styles of extensional decoupling, Geology, 1998, 26: 699.CrossRefGoogle Scholar
  36. 36.
    Zhu, G., Xu, J.-W., Sun, S.-Q., Isotopic age evidence for the timing of strike-slip movement of the Tan-Lu fault zone, Geol. Review (in Chinese), 1995, 41(5): 452.Google Scholar

Copyright information

© Science in China Press 2002

Authors and Affiliations

  1. 1.Department of Earth and Space SciencesUniversity of Science and Technology of ChinaHefeiChina

Personalised recommendations