Northward extrusion of the ultrahigh-pressure units in the southern Dabie metamorphic belt, east-central China

AbstractThe East Kunlun Orogen (EKO) is the NW part of the Central China Orogenic Belt, which records the evolutionary history of the Proto- and Palaeo-Tethys Oceans from the Cambrian to the Triassic. An Early Palaeozoic eclogite belt has been recognized in recent years, which extends discontinuously for ∼500 km as three eclogite-bearing terranes. In this study, we report an integrated study of zircon grains from mica-schists accompanying the eclogites, in terms of mineral inclusions, U–Pb age systematics and P–T conditions. The presence of coesite is identified, as inclusions within the metamorphic domain of zircons, which provides unambiguous evidence for subducted terrigenous clastic rocks of the Proto-Tethys Ocean exhumed from coesite-forming depths. U–Pb dating of the metamorphic zircons yields a concordia age of 426.5 ± 0.88 Ma, which is likely to be the time of ultrahigh-pressure metamorphism in the Kehete terrane. P–T calculations suggest that metapelite may have experienced a clockwise P–T path with peak P/T conditions of 685 ± 41 °C and >28 kbar, and equilibrated at 482–566 °C and 5.6–8.9 kbar during subsequent exhumation. The high-pressure – ultrahigh-pressure (HP-UHP) metamorphic belt within the EKO may have formed by collision between the Qaidam Block and the South Kunlun Block, as a consequence of the closure of the Proto-Tethys Ocean.

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Geochemistry of high-pressure to ultrahigh-pressure granitic melts produced by decompressional melting of deeply subducted continental crust in the Sulu orogen, east-central China

Geochimica et Cosmochimica Acta ◽

10.1016/j.gca.2020.08.005 ◽

2020 ◽

Vol 288 ◽

pp. 214-247 ◽

Cited By ~ 1

Author(s):

Kun Zhou ◽

Yi-Xiang Chen ◽

He-Zhi Ma ◽

Yong-Fei Zheng ◽

Xiao-Ping Xia

Keyword(s):

High Pressure ◽

Continental Crust ◽

Central China ◽

Ultrahigh Pressure ◽

East Central ◽

Decompressional Melting

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Precise Re-Os Dating of Molybdenite from the Northern Dabie Molybdenum Belt in Central China and its Geodynamic Implications

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.1035 ◽

2012 ◽

Vol 535-537 ◽

pp. 1035-1038

Author(s):

Jun Ping Li ◽

Yong Feng Li ◽

Ke Jia Xie

Keyword(s):

North China ◽

Central China ◽

Metamorphic Belt ◽

Dabie Orogen ◽

East Central ◽

The North ◽

Metallogenic Belt ◽

Vein Type ◽

Granite Porphyries ◽

Granitoid Intrusions

The Dabie orogen of east-central China marks the boundary between the North China and Yangtze Cratons, and is characterized by juxtaposition of the ~400Ma Tongbai metamorphic belt and the ~220Ma South Qinling-Dabie metamorphic belt. The Triassic collision between the North China and Yangtze Cratons which generated numerous granitoid intrusions such as the Shangcheng, Xingxian and Lingshan intrusions, and other small stocks, such as Tangjiaping, Dayinjian, Mushan and so on. Those shallow-emplaced granite porphyries are closely related to porphyry-skarn Mo and Mo-W deposites, forming the Dabie molybdenum metallogenic belt. Molybdenum deposits occur in the endo- and exocontact zones of the porphyry, include with three major types of Mo mineral systems, i.e., porphyry, less porphyry-skarn and vein-type. The ore-forming ages of the molybdenum deposits in Dabie area are mainly cluster 127.8±0.9~113.1±7.9Ma. The pulse is the product of the transformation of the tectonic regime from NS- to nearly EW-directions in East China.

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