The Wutaishan orogenic belt within the Shanxi Province, northern China: a record of late Archaean collision tectonics

Abstract The Archaean crust of northeastern Shanxi Province, northern China, is dominated by three distinct terranes: the high-grade gneiss terranes Hengshan in the north and Fuping in the southeast, and the intervening low-grade terrane of the Wutaishan belt. The 2.5 Ga Beitai arc complex which constitutes the major part of the Wutaishan belt is interpreted as a pre-collision magmatic arc. There was a marginal-sea basin between the Beitai arc and the Fuping terrane. At the fore-arc collision stage the passive margin deposits which occurred along the western margin of the Fuping terrane became a foreland fold-thrust belt after the closure of the marginal-sea basin. The remnants of sea floor occur as a melange zone along the suture zone between the Beitai arc and Fuping terrane. Nearly at the same time, at ∼ 2.5 Ga, the back-arc oceanic lithosphere started to subduct beneath the Hengshan terrane, then the Hengshan terrane came into collision with the arc and the Fuping terrane. Some dismembered sea-floor rocks are preserved as a back-arc melange zone between the Hengshan terrane and the Beitai arc. The term ‘Wutaishan Orogeny’ should be reserved for the processes which lasted from 2600 to 2450 Ma.