On The Mesozoic Tectonic Deformation Characteristics Of The Craton In Eastern China

Chinese geologists carried out a lot of research and published a series of papers about Mesozoic structure deformation in Yanshan area, northern Sino-Korean craton and in Sichuan, Guizhou, Hunan, Hubei, eastern Upper Yangtze craton. Among them, there are two ideas about Mesozoic deformation in South China, i.e., the cover detachment along the surface of unconformity, and basement-involved folding; similarly, for Sino-Korean carton, there are also two views of metamorphic core complex and basement-involved thick-skinned fold. The author did a detailed field geological survey along the Jingle-Xingtai section in central Shanxi and the Fanjingshan anticline in eastern Guizhou, and made chronological and geochemical analysis of the intrusive rocks associated with Mesozoic tectonics in the core of the Malanyu anticline. On these grounds, preliminary conclusions are drawn as follows: 1) The central Sino-Korean craton is represented by broad and gentle NE trending anticlines and synclines. Thrust faults developed at the east limbs of the anticlines of section â… -â… `, leading to strata overturning; Thrust faults developed at the both limbs of the anticlines of sectionâ…¡-â…¡`, causing the basement to push onto the sedimentary cover. Therefore, it can be seen that the Mesozoic tectonic deformation central Sino-Korean craton, is characterized by basement-involved structure, and as a result, the basement was folded together with the cover. 2) LA-MC-ICP-MS zircon U-Pb dating and petro-geochemical features of the Mesozoic intrusive rocks in the Malanyu anticline core show that this anticline was initiated in the Indosinian period, and formed finally in the Yanshanian phase â…¡. The Indosinian-Yanshanian orogeny not only contributed to the crust thickening, but also resulted in partial melting of the lower crust, bringing about the occurrence of intrusive bodies along the anticlinal core. 3) For the eastern Upper Yangtze craton, the Banxi group in the lowest part of the sedimentary cover in Fanjingshan, eastern Guizhou obviously unconformably rests on the Fanjingshan group to form a broad and gentle anticline structure, whose cleavages related to the cover folding cut through the unconformity into the basement, suggesting that the cover of the Banxi group did not slide along the surface unconformity, and that the basement of the Yangtze craton was folded together with its cover. 4)From the Hengyang-Huayingshan tectonic section, it is clear that to the east of the Jiangnan anticlinorium, the south china Caledonian basement in central Hunan was intensely folded, with the intrusion of granite rocks into the anticline core; To the west of it, the Yangtze craton basement was slightly folded; And further towards the west folding took place only in the cover which demonstrates that the Mesozoic tectonism of south China reduced from east to west.