Extension Model of Crustal Uplifting in Western Shandong

Abstract

Abstract Block faults, as the dominant tectonic framwork of western Shandong, were formed by the linked extensional fault system through two extensional movements during the Meso‐Cenozoic. Both of the extensional movements experienced the same evloutional process: first, the upper crust was pulled apart to form faults; then the Tai‐Lu‐Yi (Taishan‐Lushan‐Yishan) fault block occurring in the footwall of the extensional fault was uplifted, which induced the shallow‐level detachment movement along the early Precambrian and Palaeozoic unconformity; the “branching” fault in the upper part of the deep‐level detachment layer propagated. As the shallow detachment moved towards the north and the deep one towards the south, the Tai‐Lu‐Yi fault block acted as the common footwall of both the southern and northern detachment systems. The Tai‐Lu‐Yi fault block rebounded and uplifted as the overlying material was pulled apart to cause an unloading. Sialic material of the mid‐crust below the deep detachment flowed to and accumulated in the free space below the rebounding uplifted body and thickened the body; whereas the mid‐crust thinned under the graben systems. The rebounding uplifted body cooled, and then the graben system was occluded, which resulted in the crust‐mantle isostatic adjustment and asthenospheric convection. As a result of the two extensional movements, the uplifted central Shandong block with the Tai‐Lu‐Yi area as the core stands highly above the surrounding plain characterized by graben systems. The present Mount Taishan forms the climax of the uplift.