Paleoproterozoic high-pressure metam
Source: Nature   Publish Time: 2016-05-23 18:17   215 Views   Size:  16px  14px  12px

Abstract: The connection between the North China Craton (NCC) and contiguous cratons is important for the configuration of the Nuna supercontinent. Here we document a new Paleoproterozoic  high-pressure (HP) complex dominated by garnet websterite on the northern margin of the  NCC. The peak metamorphism of the garnet websterite was afterB1.90 Ga when it was subducted to eclogite facies atB2.4 GPa, then exhumed back to granulite facies atB0.9 GPa beforeB1.82 Ga. The rock associations with their structural relationships and geochemical affinities are comparable to those of supra-subduction zone ophiolites, and supported by subduction-related signatures of gabbros and basalts. We propose that aB1.90 Ga oceanic fragment was subducted and exhumed into an accretionary complex along the northern margin of the NCC. Presence of the coeval Sharyzhalgai complex with comparable HP garnet websterites in the southern Siberian active margin favours juxtaposition against the NCC in the Paleoproterozoic.

Xiao W. Paleoproterozoic high-pressure metamorphism in the northern North China Craton and implications for the Nuna supercontinent[J]. Nature Communications, 2015, 6. [pdf]