What brought them up? Exhumation of the Dabie Shan ultrahigh-pressure rocks

Publisher Website
Google Scholar
Abstract
Metamorphic coesite and diamond in the Dabie Shan, eastern China, testify to sub- duction of continental crust to >100 km depth. Exhumation of these ultrahigh-pressure rocks through the crust encompassed two stages. (1) South-dipping foliation, southeast- plunging stretching lineation, lineation-parallel isoclinal folds, and boudins indicate ex- treme subhorizontal shortening and subvertical extension during top-to-northwest shear- ing at 200-180 Ma. Syntectonic recrystallization occurred at eclogite and amphibolite facies temperatures and at pressures below coesite stability. (2) Northwest-southeast sub- horizontalextensionfrom133to122Mawasconcentratedwithinanasymmetricstructural dome in a magmatic complex that forms the northern half of the Dabie Shan. Pluton cores at deep structural levels have weak hypersolidus fabrics, and pluton carapaces are mylo- nitic gneisses formed at upper amphibolite facies conditions. Deformation is concentrated in greenschist facies mylonites and ultramylonites along the Xiaotian-Mozitang detach- mentfaultatthenortherntopographiclimitoftheDabieShan.Ourpreferredexhumation model involves two stages: Triassic indentation—vertical extrusion and erosion—followed by Cretaceous plate margin transtension.

This publication has 0 references indexed in Scilit: