Detrital Zircon LA-ICP-MS U-Pb Age of Late Carboniferous to Early Permian Sandstones in Central Great Xing'an Range and Its Geological Significance

Zhao Yingli; Liu Yongjiang; Li Weimin; Feng Zhiqiang; Wen Quanbo; Liang Chenyue

Abstract：Northeast China,located in the eastern part of the Central Asian orogenic belt (CAOB),is composed of several mi-cro-blocks (e.g.Erguna block,Xing'an block,Songliao block and Jiamusi block).However the suturing locations,timing and the amalgamation processes among the micro-blocks are still unclear.This study focuses on the systematic study on petrogra-phy and detrital zircon LA-ICP-MS U-Pb ages of the Late Carboniferous to Early Permian sandstones from the Baoligaomiao Formation in the Moguqi area,Central Great Xing'an range,in order to reveal the tectonic background of the provenances and constrain the evolution history of the Xing'an and Songliao blocks.Petrographically,detrital compositions show that the inves-tigated sandstones are immature,probably due to rapid erosion,transportation,and diagenetic processes,as well as nearly supplying from the source area.Additionally,the abundance of volcanic lithic reveals that the magmatic provenance dominates. Meanwhile,the cathodoluminescence (CL)images,Th/U ratios and REE pattern of analyzed zircons also imply the igneous origin.Zircon U-Pb ages obtained from the analyzed samples are mainly concentrated in 282—360 Ma (n＝134),with the peaks at ca.290 Ma,305 Ma,325 Ma and 350 Ma.By combining our new geochronological data with previous regional reports,it is concluded that the provenance of the sandstones is possibly derived from the subduction-and syn-collision-related Paleozoic magmatic arc along the Moguqi-Nenjiang-Heihe areas.Furthermore,the youngest zircon U-Pb ages of 282±4 Ma (sample 15MG10)and 287±4 Ma (sample 15MG11)give the lower limit age of sediments.Comparing the detrital zircon U-Pb concen-trations of the Late Carboniferous to Early Triassic sandstones in the Suolun-Moguqi areas,it is found that there is no differ-ence between the Late Carboniferous to Early Permian clastic components in the Xing'an block and the Middle Permian to Early Triassic ones in the Songliao block,indicating the above mentioned two blocks have been amalgamated before Late Carbonifer-ous period along the Hegenshan-Heihe suture zone.