Early Palaeozoic high-pressure granulites from the Dunhuang block, northeastern Tarim Craton: constraints on continental collision in the southern Central Asian Orogenic Belt

摘要: The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary collages in world, and records a prolonged sequence subduction-accretion collision processes. Tarim Craton located at southernmost margin CAOB. In this study, discovery early Palaeozoic high-pressure (HP) granulites from Dunhuang block northeastern reported, these rocks are characterized through detailed petrological geochronological studies. peak mineral assemblage HP mafic granulite garnet + clinopyroxene plagioclase quartz rutile, which overprinted by amphibolite facies retrograde metamorphic assemblages. calculated P-T conditions metamorphism � 1.4-1.7 GPa 800 C. 0.7 700 zircon grains show homogeneous CL-images, low Th ⁄ U ratios flat HREE patterns yield weighted mean 206 Pb 238 age 444 ± 5 Ma. associated kyanite-bearing gneiss garnet-mica schist similar 429 3 435 4 Ma, respectively. c. 440-430 Ma interpreted to mark timing block. results study suggest that experienced continental subduction prior collisional orogeny between southern CAOB, area could be considered as southward extension It suggested eastern part involving CAOB may have occurred 120 earlier than western Tianshan orogen.