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In the Triassic suture between the Sino-Korean and Yangtze cratons,the Qinling-Dabie metamorphic complex includes three tectonic units: a northern migmatitic terrane( P < 20 kb),a central UHP coesite- and diamondbearing eclogite belt(20 ~ 40 kb),and a southern HP blueschist-eclogite belt(5 ~ 12 kb). Protoliths include continental basement of late Archean to Proterozoic granitic gneiss complexes,and mid-to late Proterozoic bimodal volcanics,platform carbonates,and turbidite sequences including peraluminous sediments. Some early Paleozoic rocks are included as protoliths in the HP belt. The metamorphic complex is segmented into several large blocks by NE-SW trending faults. Three( Dabie,Hongan and Wudan) occur in central China,and an eastern extension,the Su-Lu block is displaced to the north by the Tanlu fault. The UHP rocks are best exposed in the Dabie and Su-Lu blocks,whereas HP blueschists occur throughout the Hongan and Wudan blocks. Widespread occurrence of conjugate faults in the metamorphic complex suggests differential doming after tectonic juxtaposition of the UHP and HP units at shallow crustal levels. Eclogites of the UHP belt occur as blocks in ultramafic rocks,marble and gneiss and as thin layers interbedded with gneiss; some contain coesite and coesite pseudomorphs in garnet,omphacite,kyanite and epidote. Microdiamond inclusions in garnet have been reported. C-type glaucophane-bearing eclogites are restricted to the Hongan HP belt and contain paragonite instead of kyanite. The coherent HP terrane displays progressive zonation from transitional blueschist / greenschist,through greenschist and epidote amphibolite to eclogite assemblages. The UHP and HP belts possess similar metamorphic trends,deformation features and record clockwise P-T paths. Disposition of the UHP belt to the north of the HP belt,the northward increase in metamorphic grade,and the southward vergence of structures suggest formation during northward underflow of a microcontinent beneath the Sino-Korean craton prior to early Mesozoic collision. Great differences in metamorphic pressure suggest that tectonic juxtaposition of these units occurred by extrusion of subducted continental fragments.
In the Triassic suture between the Sino-Korean and Yangtze cratons, the Qinling-Dabie metamorphic complex includes three tectonic units: a northern migmatitic terrane (P <20 kb), a central UHP coesite- and diamondbearing eclogite belt (20-40 kb) , and a southern HP blueschist-eclogite belt (5-12 kb) Protoliths include continental basement of late Archean to Proterozoic granitic gneiss complexes, and mid-to late Proterozoic bimodal volcanics, platform carbonates, and turbidite sequences including peraluminous sediments. Some early Paleozoic rocks are included as protoliths in the HP belt. The metamorphic complex is segmented into several large blocks by NE-SW trending faults. Three (Dabie, Hongan and Wudan) occur in central China, and an eastern extension, the Su-Lu block is displaced to the north by the Tanlu fault. The UHP rocks are best exposed in the Dabie and Su-Lu blocks, where HP blueschists occur throughout the Hongan and Wudan blocks. Widespread occurrence of conjugate faults in the metamorphic complex suggests differential doming after tectonic juxtaposition of the UHP and HP units at shallow crustal levels. Eclogites of the UHP belt occur as blocks in ultramafic rocks, marble and gneiss and as thin layers interbedded with gneiss; some contain coesite and coesite pseudomorphs in garnet , omphacite, kyanite and epidote. Microdiamond inclusions in garnet have been reported. C-type glaucophane-bearing eclogites are restricted to the Hongan HP belt and contain paragonite instead of kyanite. The coherent HP terrane displays progressive zonation from transitional blueschist / greenschist, through greenschist and epidote amphibolite to eclogite assemblages. The UHP and HP belts taken on similar metamorphic trends, deformation features and record clockwise PT paths. Disposition of the UHP belt to the north of the HP belt, the northward increase in metamorphic grade, and the southward vergence of structures suggest formation during northward underflow of a microcontinent beneaththe Sino-Korean craton prior to early Mesozoic collision. Great differences in metamorphic pressure suggest that tectonic juxtaposition of these cells occurred by extrusion of subducted continental fragments.