Meso- to Neoproterozoic zircon xenocrysts in Late Carboniferous granite from the western Xing'an Block: Record of the supercontinent evolution

Whether and how the micro-continents in eastern Central Asian Orogenic Belt, such as Xing'an Block, were involved in the evolution of Columbia and Rodinia supercontinents, is a hot issue.A large number of Proterozoic (especially Greenville age) zircon xenocrysts present in the late Carboniferous granite from the Airgin Sum area in the western Xing'an Block, provide important constraints on the connection between the Xing'an Block and the supercontinent evolution.LA-ICP-MS zircon U-Pb dating shows that the biotite monzogranite intruded into the Airgin Sum Group at 317±3 Ma, and the biotite monzogranite captured numbers of Paleo- to Neoproterozoic (1827~1768 Ma, 1556~1526 Ma, 1195~1082 Ma, 964 Ma, 665 Ma) and Early Paleozoic (485~441 Ma) zircon xenocrysts.Those Paleo- to Neoproterozoic zircon xenocrysts might be derived from the coeval magmatic rocks in the study area instead of the meta-sedimentary rocks of the Airgin Sum Group, of which the ca.1.8 Ga, 1.5 Ga and 0.95 Ga magmatism has been reported in the Xing'an Block and its adjacent regions.The variation trends of Hf isotopes and trace elements of the Proterozoic zircon xenocrysts with time correspond to the process through Columbia breakup to Rodinia assembly.For instance, the depleted Hf isotope characteristics and thicker crustal thickness revealed by 1.5~1.4 Ga zircon xenocrysts might be related to the peripheral subduction around the Columbia supercontinent.The increased Eu/Eu^* and (La/Yb)_N ratios of zircons from 1195 Ma to 1082 Ma might be related to the crustal thickening associated with the Rodinia assembly, while the higher temperatures and lower Eu/Eu^* and (La/Yb)_N ratios of 964 Ma and 665 Ma zircons are consistent with the collapse extension after the Greenville Orogeny (1080~980 Ma) and the breakup of Rodinia.These studies indicate that the Xing'an Block might have been involved in the Proterozoic supercontinent evolution.