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Zircon Ages of the Haizhou Group in the Southern Part of the Sulu Ultrahigh Pressure Orogenic Belt and Geological Significances

WANG Xiu-li1, LI Xiang-hui1,2, CHEN Fu-kun1,3, LI Qiu-li1, GUO Jing-hui2   

  1. 1. Laboratory for Radiogenic Isotope Geochemistry, Institute of Geology and Geophysics, Chinese Academy of Sc/enees, Belting 100029
  • Received:2006-09-20 Revised:2006-09-20 Online:2006-09-20 Published:2006-09-20

Abstract: Constraints of age and isotopic compositions on the metamorphic rock units exposed in the southern part of the Dabie-Sulu ultrahigh pressure orogenic belt are essential for the study of regional stratigraphic comparison and further for understanding tectonic process and evolution of this orogen. In this study, Nd isotopic compositions and ages of detrital zircon of schists from the Haizhou Group in the southern part of the Sulu terrain are presented. Detrital zircon gains of three schist samples collected from the Yuntai Formation of the upper Haizhou Group yielded ages clustering around 740 to 800 Ma. Initial εnd (800 Ma) values and two-stage depleted-mantle Nd modal ages of the schist samples range from - 12.8 to - 8.8 and from 2.1 to 2.4 Ga. These ages and isotopic characteristics of the Yuntai schists are similar to those of paragneisses exposed in the Susong area of the Dabie Mountains and indicate a relatively single sedimentary source. Combined with a regional stratigraphic comparison, ages of the detrital zircons can place a constraint of Neoproerozoic age, later than about 740 Ma, for the deposition time of the Yuntai Formation. The sedimentary material was likely originated from Neoproterozoic magmatic rocks having an affinity of the Yangtze block.