Whole-rock Ar-Ar dating for low-grade metavolcanics within the Dabie orogen and its geological significance

A perspective view on ultrahigh-pressure metamorphism and continental collision in the Dabie-Sulu orogenic belt

“…Shallow-level detachment in the interior of the upper crust (mainly between sedimentary cover and crystalline basement) is argued to occur during the Triassic continental collision [31] , forming tectonic wedge along the suture zone in the early stage of continental subduction. This argument is based on the observations that low-grade metaigneous rocks of mid-Neoproterozoic protolith ages occur in the northern margin and interior of the Dabie-Sulu UHP zones [29,[92][93][94][95][104][105][106][107] and that impure marbles in the southern margin of the North China Block are primarily volcanosedimentary rocks of mid-Neoproterozoic ages but underwent Triassic highgrade metamorphism [108] . The tectonic wedging mechanism also provides resolution to occurrence of the so-called low-grade metavolcanics within the Dabie UHP zone that would be subducted to mantle depths but did not acquire the UHP record [109] .…”