Objective The Hadean zircon and rock are critical to deepening our understanding of the developmental history of early Earth, making possible new avenues for the Pre-Archean Eon. However, the Hadean rock on Earth is only identified in Canada indeed. Comparatively, the Hadean zircon has attracted considerably more attention, as it is widespread and exhibits robust chemical and physical features that make it survive in extreme conditions, thereby providing a method of deciphering the evolution of the early Earth. It should be noted that most of the detrital or the xenocrystic zircons older than 4.0 Ga are found in Western Australia. Hadean zircon occurrences outside Western Australia have been also reported in Canada, west Greenland and China. For the first time,
SHRIMP U-Pb zircon 207 Pb/206 Pb ages were obtained from two drill cores from the basement of the Ordos Basin.A garnet-sillimanite-biotite-plagioclase gneiss(QI1-1) from the western Ordos Basin basement yielded an average age of 2031 10 Ma.Based on the mineral assemblages,the source material of the gneiss is speculated to be pelitic-felsic system.A gneissic two-mica granite(Long1-1) from the eastern Ordos Basin basement yielded an average age of 2035 10 Ma.The zircons from both samples exhibit magmatic growth pattern.The shapes of the zircons suggest that the zircons should crystallize from a granitic of felsic volcanic terrain.The ages and the characters of zircons are consisitent with the other researches in the Ordos Basin and indicate that the basement of the Ordos Basin had experienced an intensive magmatic epsode during the late Paleoproterozoic period.The date from this study suggest the possible existences of a Paleoproterozoic mobile tectonic belt in the region.The reconstruction of such a belt is critical for understanding the tectonomagmatic evolution of the western block of the North China Craton.
HU JianMinLIU XinSheLI ZhenHongZHAO YueZHANG ShuanHongLIU XiaoChunQU HongJieCHEN Hong
