Detrital Zircon U-Pb Geochronology Characteristics and Geological Significance of the Ebian Group in the Western Yangtze Block
[Objective]The Ebian Group in the western Yangtze Block has traditionally been regarded as a represen-tative lithostratigraphic unit of the Late Mesoproterozoic in South China.The sedimentation age and provenance characteristics of the Ebian Group can provide important constraints for reconstructing the Meso-Neoproterozoic tectonic evolution of the Yangtze Block under the background of the assembly of the global Rodinia supercontinent.[Methods]In this study,petrological and detrital zircon U-Pb geochronological analyses were conducted on metasedimentary rocks of the Ebian Group.[Results]The detrital zircon ages of two metamorphic fine-grained litharenite sandstones from the Jiadanqiao Formation of the Ebian Group range from 1 950 Ma to 900 Ma.The main relative probability peaks are ca.910,1 570,and 1 730 Ma,with secondary peaks at ca.1 130,1 390,1 840,and 2 500 Ma.The maximum depositional ages are 908±8 Ma(MSWD=0.10,n=5)and 905±5 Ma(MSWD=0.52,n=9),respectively.[Conclusions]Combined with regional geological data,the depositional age of the Jiadanqiao Forma-tion of the Ebian Group is constrained as 910-860 Ma.The sediment source was magmatic rocks in the western Yangtze Block,with a predominant direction towards the south.Thus,formation likely occurred during the Early Neoproterozoic micro-block assembly and can be associated with the global assembly of the Rodinia supercontinent.
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