New Findings in High-Pressure and Ultrahigh-Pressure Metamorphic Belt of Tongbaishan-Dabieshan Regions, Central China |
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| Authors: | You Zhendong Zhong Zengqiu Suo Shutian Zhang Zeming Wei Bize |
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| Abstract: | The Tongbai Dabieshan high pressure (HP) and ultrahigh pressure (UHP) belt is sandwiched between the Yangtze and the Sinokorean cratons. It connects the Qinling orogenic belt in the west and links toward the east to the Sulu ultrahigh pressure (UHP) belt. At present there is a consensus that the UHP metamorphic rocks are the products of the oblique collision between the Yangtze and Sinokorean cratons during the Triassic. However, there is still a lot of controversies about the formation and exhumation of the HP and UHP metamorphic belts. The present research work on the composition and the structural geometry and kinetics of the HP and UHP metamorphic belt has shown the following new results: (1) The overall structural geometry pattern of Dabieshan is similar to the metamorphic core complex developed in the western North America; (2) The discoveries of HP and UHP metamorphic rocks in the north of Dabieshan indicate that the significance of Shuihou Wuhe fault should be re evaluated; (3) A series of micro structural evidence, including the newly found retrograde granulite facies assemblages in the garnet pyroxenites, substantiate the extensional processes following the collision event; (4) The discovery of partial melting phenomena in the UHP metamorphic belts illuminates the relationship between the HP and UHP metamorphic rocks and their associated granite gneiss. All of these new findings will greatly improve our understanding of the formation and exhumation of the high pressure and ultrahigh pressure metamorphic belts. |
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| Keywords: | metamorphic core complex garnet pyroxenite retrogressive microstructure flecky gneiss partial melting |
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