Provenance Analysis of the Liantuo Formation in the Dahongshan Area,Northern Yangtze Block:Evidence from sedimentology and detrital zircon U-Pb chronology
[Objective]The Liantuo Formation is a key mid-Neoproterozoic stratigraphic unit in the Dahongshan area of the Yangtze Block,South China.Its deposition time coincides with the breakup of the Rodinia supercontinent,and it is the last sedimentary layer before the Sturtian Ice Age of the first snowball Earth.However,its deposition time and provenance need further study.[Methods]The study adopted U-Pb chronology of detrital zircons,paleoflow direction and gravel composition analysis from Liantuo Formation in this area.[Results]The sedimentation time is ca.800-714 Ma,and major peaks of detrital zircons appear at approximately 2 500 Ma,2 000 Ma,880 Ma and 820 Ma,with secondary peaks at ca.780 Ma.The provenance of the Liantuo Formation in the study area is from the depositional recycling of the Dagushi Group and Huashan Group in the lower strata,and from Archean to Neopro-terozoic magmatic rocks in the northern Yangtze Block.[Conclusions]This suggests that the provenance of the Lian-tuo Formation is mainly from the northeast of the study area.Regions in western Hubei,southeastern Hubei to north-western Jiangxi,southwestern Hubei to northern Hunan,and Dahongshan in northern Hubei,have similar detrital zircon peaks corresponding to Archean,Paleoproterozoic and Neoproterozoic ages.The distribution of magmatic rocks in the northern to southeastern Yangtze Block suggests that the provenance of the Liantuo Formation in the northern Yangtze Block produced a northerly to northeasterly supply.This implies that the paleogeographic pattern in the north-ern to southeastern margin of the Yangtze Block comprised high elevation in the north,low in the south,steep in the north and gradually sloping in the south.
Yangtze BlockNeoproterozoicLiantuo Formationdetrital zirconpaleoflow direction
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