Complex evolution of the southern margin of the North China Craton: Evidence from LA-ICPMS U-Pb dating of zircons in Zhouzhuang meta-gabbro

Zhouzhuang meta-basic pluton in Xinyang, Henan Province, locates at the southern margin of the North China Craton. It is mainly composed of plagioclase + amphibole ( + epidote). The relict-gabbro texture can be found in some samples, suggesting that the rocks belong to meta-gabbro experienced epidote-amphibolite facies-low-amphibolite facies metamorphism. Zircons of two samples were analyzed, using LA-ICPMS for U-Pb ages. Both samples give concordant upper intercept age of 859Ma, but concordant lower intercept ages of them are 356 +/- 82Ma and 234 +/- 36Ma, respectively. One sample also gives another two groups of the concordant ages with the Pb-206/U-238 ages of 616 +/- 10Ma and 442 +/- 6. 5Ma. We interpret the upper intercept age of 859Ma as the intruding age of the basaltic magmatism, corresponding to the breakup of the Rodinia Supercontinent, which recorded at the southern margin of the North China Craton; the others record that the pluton underwent subsequent metamorphism and modifications, including the rifting event at the southern margin of the North China Craton in Late Neoproterozoic, and intense modifications due to subduction and collision of the Yangtze Craton in Paleozoic and in Early Mesozoic.