What drove late Mesozoic extension of the northern China-Mongolia tract?
会议名称：《中国科学院地质与地球物理研究所2003学术年会》
会议日期：2003年
学科分类：070904[理学-构造地质学] 0709[理学-地质学] 07[理学]
基 金：supported by grants from Innovation Programs of Chinese Academy of Sciences (KZCX 1-07-3 KZCX 2-104)
关 键 词：Crustal extension Gravitational collapse Yinshan Daqing Shan Northern China and Mongolia
摘 要：The northern China-Mongolia tract exhibited a tectonic transition from contractional to extensional deformation in late Mesozoic *** Middle to early Late Jurassic crustal shortening is widely thought to have resulted from collision of an amalgamated North China-Mongolia block and the Siberian plate,but widespread late Late Jurassic-Early Cretaceous extension has not been satisfactorily explained by existing *** prominent features of the extensional tectonics of the northern China-Mongolia tract are:(1) Late Jurassic voluminous volcanism prior to Early Cretaceous large-magnitude rapid extension;(2) overlapping in time of contractional deformation in the Yinshan-Yanshan belt with development of extension-related basins in the interior of the northern China-Mongolia tract;and(3) widespread occurrence of alkali granitic plutonism. extensional basins and metamorphic core complexes in the Early Cretaceous.A new explanation is advanced in this study for this sequence of *** collision of amalgamated North China-Mongolia with Siberia led to crustal overthickening of the northern China-Mongolia tract and formation of a high-standing *** breakoff at depth of the north-dipping Mongol-Okhotsk oceanic slab is suggested as the main trigger for late Mesozoic lithospheric extension of that *** breakoff resulted in mantle lithospheric stretching of the adjacent northern China-Mongolia tract with subsequent ascent of hot asthenosphere and magmatic underplating at the base of the ***,these phenomena triggered gravitational collapse of the previously thickened crust,leading to late Late Jurassic-Early Cretaceous crustal extension,and importantly, coeval contraction along the southern margin of the plateau in the Yinshan-Yanshan *** proposed model provides a framework for interpreting the spatial and temporal relationships of distinct processes and reconciling some seemingly contradictory phenomena,such as the synchronous ext