FEATURES OF SYN-TECTONIC MAGMATIC FLOW IN THRUST AND STRIKE-SLIP BELTS: COMPARED WITH MYLONITE AND GNEISS IN CHINA

Syn-tectonic magmatic flow, which typically occurs along continental margins or in orogenic belts constrained by tectonic stresses, may indicate re-melting of middle-lower crust, tectonic setting of the magmatic plutons or the reactivation of cratonic basement. Also, the differences between magmatic flow and metamorphic gneiss and mylonite constitute important problems that should be reconsidered in modern petrology and structural geology. The northern margin of the North China block hosts Late Carboniferous granitoid plutons (320-300 Ma) showing evidence of magmatic flow contain a south-vergent shallow-dipping transposition foliation and recumbent folds. The occurrence of southward magmatic flow formed in compressional tectonic setting from north to south indicates the reactivation of North China cratonic basement.

Granitoid plutons emplaced at Early Cretaceous with NE-SW trending distribution, which scattered along Changle-Nanao ductile shear zone in southeastern China are syn-strike-slip magmatic/sub-magmatic flow. These granitoids, same time as the ductile shear zone, show intense schlieren layering of mafic and felsic minerals, k-feldspar phenocrysts aligned, elongated and lenticular microgranitoid enclaves aligned parallel to the magmatic fabrics without internally deformation. Syn-ductile shear magmatic flow was contemporaneous with oblique subduction of the West Pacific Plate beneath the Eurasian continent.