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Multiple high- a ultrahigh-pressure orogenies in the Qinling Mountains boundary conditions permitting their formation and exhumation.

Research Project
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01.04.2010
 - 31.12.2010

The Qinling project aims to understand how high- and ultrahigh-pressure (UHP) metamorphic rocks form and exhume during tectonometamorphism. These investigations will (i) establish the value of four recently discovered and/or enigmatic eclogite facies (HP and UHP) events in the Qinling of central eastern China for research on HP-UHP orogeny; (ii) set up the physico-chemical and structural boundary conditions that permitted formation and exhumation of these rocks; and (iii) make first-order contributions to the understanding of the centrepiece of Chinese geology, the Qinling orogenic collage. To solve this problem, an inter-disciplinary project with international scientific partners was initiated. While our scientific partners in Germany, the research group of Lothar Ratschbacher (Freiberg University) mainly concentrates on structural geology and - in co-operation with U.S. American partners - on geochronology, the Basel working group mainly performs metamorphic petrology (PTtd-paths), HP/UHP geochemistry, and monitoring of the fluid flow in the slab. In the last two years, we made significant steps toward these goals. In the following, we highlight aspects of these goals that were not achieved yet and outline our approach for the new project. Our work centres on a final field season that addresses key aspects in the following metamorphic terranes: 1.) HP-UHP metamorphism (event 1) in the Songshugou ophiolite, southern Qinling: we will focus on working out the P-T data and the intrusion age of the ophiolite. 2.) HP-UHP metamorphism (event 2) of diamond eclogite and gneiss within accretionary complex of the northern Qinling: we will better constrain the UHP metamorphism and its retrogression. 3.) HP-UHP metamorphism (event 3) in the Huwan mélange and record of Devonian-Permian Paleotethys subduction: we need to address its P-T history, elaborate its stratigraphic range with detrital zircon geochronology, and undertake a detailed zircon study to identify those that might have been derived from eclogites and date them. 4.) HP-UHP metamorphism (event 4) during the Late Permian-Triassic collision and subduction of the leading edge of the Yangtze craton: HP/LT metamorphism in the Wudang and the Duoling: we discovered a HP/LT metamorphism in the Duoling complex and want to will link this metamorphism to similar rocks of the Tongbai and Zhangbaling/Susong belt of Dabie. 5.) HP-UHP metamorphism (event 4) in the Tongbai area: we will constrain the peak metamorphic conditions of the eclogites and get further insight into the tectonometamorphic evolution of this area.

Members (3)

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Leander Franz

Principal Investigator
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Christian E. De Capitani

Co-Investigator
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Josef Mullis

Co-Investigator