c. 1.85 Ga HP granulite-facies metamorphism in the Dunhuang block of the Tarim Craton, NW China: evidence from U-Pb zircon dating of mafic granulites

Mafic granulites of the Dunhuang block, eastern Tarim Craton, record high-pressure granulite-facies metamorphism followed by a medium-to low-pressure granulite-facies metamorphic overprint, suggesting a clockwise P-T path and implying an environment of collisional orogenesis. Zircon U-Pb ages of two samples are 1834 +/- 12 Ma and 1842 +/- 5 Ma. Mineral inclusions in zircon indicate that these ages record the high-pressure granulite-facies event, suggesting that the Tarim Craton may be related to the c. 1.85 Ga assembly of the Columbia supercontinent. Similar c. 1.85 Ga metamorphism in both the Dunhuang block and the Alxa block of the North China Craton supports their correlation across the Altyn Tagh fault.