HAL : insu-00576322, version 1

DOI : 10.1016/j.gr.2011.02.013

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Gondwana Research 20 (2011) 498-515

Syn-collisional channel flow and exhumation of paleoproterozoic High Pressure rocks in the Trans-North China Orogen: the critical role of partial-melting and orogenic bending

Pierre Trap 1, Michel Faure 2, Wei Lin 3, Romain Augier 2, Antoine Fouassier 2

(2011)

Within the paleoproterozoic Trans-North China Orogen, the High-Pressure Belt (HPB) is made of high-pressure (~ 15 kbar) mafic granulites hosted in migmatitic gneisses. In this contribution, we document a set of structural analyses acquired over the whole HPB. We also proposed a morphological subdivision of the partially molten rocks that compose the HPB according to changes in melt fraction. A compilation of the P-T and radiochronological data carried out over the last 15 years is presented. The results highlight the concurrent effect of oroclinal bending and partial-melting in controlling the exhumation of the deeply buried continental crust. During ongoing compression of the thickening orogenic root, onset of partial-melting at peak metamorphism is responsible for a first strength drop that enhanced an eastward lateral flow. Radiometric ages show that the deep crust was partially molten over a 50 Ma lasting period during which it evolved in a diatexite core mantled by metatexites. This was responsible for a second strength drop with strain concentrated along the diatexite/metatexite boundaries, as exemplified by the newly documented Datong-Chengde Shear Zone, a ~ 400 km-long normal shear zone with a sinistral strike-slip component that accommodated the final uprise of the high-pressure rocks.

1 :	Laboratoire Chrono-environnement
	CNRS : UMR6249 – Université de Franche-Comté
2 :	Institut des Sciences de la Terre d'Orléans (ISTO)
	Université d'Orléans – CNRS : UMR6113 – Université François Rabelais - Tours – INSU
3 :	State Key Laboratory of Lithospheric Evolution
	Institute of Geology and Geophysics, Chinese Academy of Sciences

domaine

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Planète et Univers/Sciences de la Terre/Tectonique Sciences de l'environnement/Milieux et Changements globaux

mots-clés : High-pressure rocks – Exhumation – Partial melting – Channel flow – Trans-North China Orogen

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Contributeur : Nathalie Pothier <>

Soumis le : Vendredi 24 Juin 2011, 11:17:39

Dernière modification le : Mardi 23 Août 2011, 14:54:23