The enigmatic Yinshan fold-and-thrust belt of northern China: New views on its intraplate contractional styles

The east- to east-northeast-trending Yinshan belt lies within North China, extending westward at least 1100 km from China's eastern coast to Inner Mongolia. This intraplate Jurassic-Cretaceous belt underwent contractional and normal faulting, folding, and contemporaneous terrestrial sedimentation and magmatism. Current views on its contractional deformational style favor relatively limited "thick-skinned" faulting of Archean basement and cover units. These views are challenged, however, by recent discoveries in the eastern part of the belt of south-directed ductile nappe formation and large-displacement (>40-45 km) "thin-skinned" northward thrust faulting, both involving Archean and younger rock units. Collision of the Siberian and North China plates upon closure of a Jurassic and Early Cretaceous Mongolo-Okhotsk ocean more than 800-1100 km to the north may have been responsible for Yinshan north-south contraction. Some patterns of contraction, e.g., Jurassic-Cretaceous ductile nappe formation, appear to have been influenced by a superposed magmatic regime related to westward subduction of a Pacific basin plate beneath the North China plate.