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Coesite eclogite facies metamorphic tectonite: Evidence for ultrahigh pressure deformation

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Chinese Science Bulletin

Abstract

An ultrahigh pressure ductile shear mélange crops out on the beach of Yangkou Bay near Qingdao City. The mélange is composed of weakly deformed blocks in a highly ductilly flow mylonites. Ultrahigh pressure metamorphic (UHPM) tectonite includes strongly deformed eclogite and mylonitized eclogite. Coesite occurs in the tectonite as both interstitial mineral and inclusions in garnet and omphacite, indicating that the deformation took place in the stability field of coesite (800–850°C, >30 GPa) in the upper mantle. Coesite is rounded or short prismatic grains with undulatory extinction, and often fractured, suggesting brittle deformation. Garnet is also characterized by brittle fractures and sometimes necked and slightly elongated. Omphacite is elongated, with long axis preferred orientation. Undulatory extinction, subgrains and dynamically recrystallized grains suggest plastic flow of omphacite. Ultrahigh pressure metamorphic tectonite was probably formed in the ductile shear zone during the early stage of exhumation of the ultrahigh pressure metamorphic rocks. Its kinematic indicators point to the transport direction of the UHPM slab during the early stage of exhumation.

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References

  1. Henry, C., Michard, A., Chopin, C., Geometry and structural evolution of ultra-high-pressure and high-pressure rocks from the Dora-Maira massif, Western Alps, Italy, Journal of Structural Geology, 1993, 15: 965.

    Article  Google Scholar 

  2. Michard, A., Henry, C., Chopin, C., Structures in UHP rocks: a case study from the Alps, Ultrahigh Pressure Metamorphism (eds. Coleman, R., Wang, X.), Cambridge University Press, 1995, 132–158.

  3. Wallis, S. R., Ishiwatari, A., Hirajima, T., Occurrence and field relationships of ultrahigh-pressure granitoid and coesite eclogite in the Su-lu terrain, eastern China, Journal of the Geological Society, London, 1997, 154: 45.

    Article  CAS  Google Scholar 

  4. Hacker, B. R., Ratschbacher, L., Webb, L., What brought them up? Exhumation of the Dabieshan ultrahigh-pressure rocks, Geology, 1995, 23: 743.

    Article  Google Scholar 

  5. Stöckhert, B., Renner, J., Rheology of crustal rocks at ultrahigh pressure (eds. Hacker, B. R., Liou, J. G.), When Continents Collide: Geodynamics and Geochemistry of Ultrahigh Pressure Rocks, Dordrecht: Kluwer Academic Publishers. 1998, 57–95.

    Google Scholar 

  6. Jin, Z. M., Zhang, J., Green II, H. W., Eclogite rheology: implications for subducted lithosphere, Geology, 2001, 29: 667.

    Article  CAS  Google Scholar 

  7. Hirajima, T., Ishiwatari, A., Cong, B. et al., Coesite from Mengzhong eclogite at Donghai County, northeastern Jiangsu Province, China, Mineralogical Magazine, 1990, 54: 579.

    Article  Google Scholar 

  8. Enami, M., Zang, Q., Quartz pseudomorph after coesite in eclogite from Shangdong Province, east China, American Mineralogist, 1990, 75: 381.

    CAS  Google Scholar 

  9. Wang, Q., Ishiwatari, A., Zhao, Z., Coesite-bearing granulite retrograded from eclogite in Weihai, eastern China: a preliminary study, European Journal of Mineralogy, 1993, 5: 141.

    CAS  Google Scholar 

  10. Yang, J., Godard, G., Kienast, J. R. et al., Ultrahigh-pressure (60 kb) magnesite-bearing garnet peridotes from northeastern Jiangsu, China, J. Geology, 1993, 101: 541.

    Article  CAS  Google Scholar 

  11. Ye, K., Yao, Y., Katayama, I. et al., Large areal extent of ultra-high-pressure metamorphism in the Sulu ultrahigh-pressure terrane of East China: new implications from coesite and omphacite inclusions in zircon of granitic gneiss, Lithos., 2000, 52: 157.

    Article  CAS  Google Scholar 

  12. Zhang, R. Y., Liou, J. G., Partial transformation of gabbro to coesite bearing eclogite from Yangkou, the Sulu terrain, eastern China, Journal of Metamorphic Geology, 1997, 15: 183.

    Article  CAS  Google Scholar 

  13. Li, S., Sun, W., Ge, N. et al., Eclogite facies ophiolite mélange in Qingdao: Its petrologic evidence and P-T path, Acta Petrologica Sinica (in Chinese), 1992, 8: 351.

    Google Scholar 

  14. Ye, K., Cong, B., Ye, D., The possible subduction of continental material to depth greater than 200 km, Nature, 2000, 407: 734.

    Article  PubMed  CAS  Google Scholar 

  15. Okay, A. I., Petrology of a diamond and coesite-bearing metamorphic terrain: Dabie Shan, China, European Journal of Mineralogy, 1993, 5: 659.

    CAS  Google Scholar 

  16. Gebauer, D., Schertl, H. P., Brix, M. et al., 35 Ma old ultrahigh pressure metamorphism and evidence for very rapid exhumation in the Dora Maira massif, Western Alps, Lithos., 1997, 41: 5.

    CAS  Google Scholar 

  17. 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 and Planetary Science Letters, 1998, 161: 215.

    Article  CAS  Google Scholar 

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Authors and Affiliations

  1. LTE Lab, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029, Beijing, China

    Zhongyan Zhao, Aiming Fang & Liangjun Yu

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  1. Zhongyan Zhao
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  2. Aiming Fang
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  3. Liangjun Yu
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Correspondence to Zhongyan Zhao.

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Zhao, Z., Fang, A. & Yu, L. Coesite eclogite facies metamorphic tectonite: Evidence for ultrahigh pressure deformation. Chin. Sci. Bull. 47, 1388–1392 (2002). https://doi.org/10.1360/02tb9306

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  • DOI: https://doi.org/10.1360/02tb9306

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