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SHRIMP U-Pb and CAMECA 1280 oxygen isotope results from ancient detrital zircons in the Caozhuang quartzite, Eastern Hebei, North China Craton Evidence for crustal reworking 3.8 Ga ago [查看] SIMONA.WILDE、JOHNW.VALLEY、NORIKOT.KITA、AARONJ.CAVOSIE、DUNYILIU

ABSTRACT. The Caozhuang quartzite, located in Eastern Hebei Province in the eastern part of the North China Craton, has long been known to contain the oldest detrital zircon population in China. A suite of 30 zircons with preliminary ages >3.7 Ga were selected for detailed SHRIMP U-Pb and CAMECA 1280 oxygen isotope analyses.SHRIMP U-Pb dating reveals that ages range from 3860 to 3135 Ma, the former being the oldest 207Pb/206Pb zircon age so far obtained from the North China Craton. Values of 18O range from 5.4 to 7.5 permil, similar to Archean igneous zircons worldwide, but the average value for the 30 zircons is 6.6 permil, which is 0.3 permil higher than suite averages for detrital zircons from the Jack Hills and Beartooth Mountains and nearly 1 permil higher than magmatic zircons from igneous rocks of the Superior Province and Barberton. These elevated values of 18O suggest reworking of a significant amount of juvenile crust, older than 3.8 Ga, that underwent a low temperature supracrustal history and was distributed throughout the source region in northeast China.