The Strata, Characteristics Of Rocks And Provenance Analysis Of Meishan Group In The Northern Margin Of The Dabie Orogenic Belt, China

The Meishan Group is a suite of slightly metamorphosed sedimentary strata in thenorthern margin of the Dabie Orogen, and it recorded the information of the provenanceand the Paleozoic tectonic evolution. However, the age, sedimentary environment andtectonic background of the strata have been controversial for a long time. The MeishanGroup is mainly distributed in Quanjun, Liqiao and Sanxianshan area of Jinzhai inAnhui. The paper analyse the compositions of major trace and rare elements, the detritalcompositions of sandstone and the U-Pb isotope dating of detrital zircons in the studyarea, and investigate the tectonic attribute and evolution of the provenance. Thelithofacies mainly includes conglomerates, sandstones and siltstones, as well as a smallamount of volcano rocks and metamorphic rocks. Medium-fine grain quartz sandstone,feldspar-quartz sandstone and lithic greywacke are the major types of the rocks in thestudy area. The detrital of sandstones, trace element and REE contents of the MeishanGroup sandstones in Jinzhai area reveal that the source rocks of the Meishan Groupwere formed under a tectonic setting of continental island arc, active continental marginand passive continental margin in the northern margin of Dabie Orogen. The chemicalindex of aiteration corrected (CIAcorr.) of the detrital rocks in Qunjun area are78.73%,whitch indicates that the provenance had mostly experiencel strong chemical weathering.According to the U-Pb ages of LA-ICP-MS of78detrital zircon grains, the source rocksof Meishan Group detrital rocks came from terrains with five different geological times,most391-477Ma and623-991Ma, second1037-1589Ma,1733-2498Ma and2539-2943Ma. These reveal that the Meishan Group sediments were derived fromdifferent provenance, including the Early Paleozoic island-arc system of the northernQinling, Late Proterozoic basement of Yangtze Craton and Middle Proterozoic-MiddleArchaean basement of North China Block．...