Geochronology and geochemistry of gneiss and migmatite from the Korla Complex in the Quruqtagh block, NW China: Implications for Proterozoic crustal evolution of the northeastern Tarim Craton

Abstract

The Korla Complex in the Quruqtagh block of the northeastern Tarim Craton records Proterozoic tectono–thermal events and provides a window to understand the role of Tarim during the Columbia–Rodinia supercontinent cycle. Here we present zircon U–Pb ages, Lu–Hf isotopic compositions and bulk–rock geochemical data of gneisses and leucosomes of migmatites from the Korla Complex. Zircon grains from the orthogneiss exhibit core–rim structure, nevertheless the core and rim domains have indistinguishable ages, and jointly defined the Paleoproterozoic metamorphism of 1842 ± 35 Ma, which was ascribed to assembly of the Tarim Craton to the Columbia supercontinent along interior accretionary orogen. The leucosomes of migmatites were formed at 814 ± 3 Ma, and the consistent Hf isotope characteristics of newly grown anatectic zircon and inherited zircon of their protolith, indicates that the migmatite was formed by in–situ crustal anatexis associated with subduction–accretion process. Therefore, it is inferred that the assembly of the Tarim Craton to the Rodinia supercontinent lasted at least until ca. 0.81 Ga. Since this accretionary orogenic event (ca. 0.81 Ga) occurred during the initial breakup stage of the Rodinia supercontinent (0.83 Ga), it indicates that the Tarim Craton was probably located at peripheral position in the Rodinia reconstruction with long-lasting peripheral subduction and accretion. Collectively, it is suggested that the Tarim Craton was involved in global scale tectonic evolution during the Columbia–Rodinia supercontinent cycle. In combination with previous studies, it is proposed that the Tarim–North China connection within the Paleoproterozoic Columbia supercontinent must have broken–up before the Tarim–South China affinity within the Neoproterozoic Rodinia supercontinent, ascribed to the breakup of Columbia supercontinent.