扬子西南盐源盆地中—晚三叠世砂岩锆石U-Pb年代学及其构造意义OA北大核心

During the Triassic period,the Yanyuan Basin served as a window for studying geological events such as the closure of the Paleo-Tethys Ocean on the western margin of the Yangtze Plate.It experienced a transition from passive continental margin to foreland basin sedimentation.Through field data collection of three profiles in the Yantang area,sandstone petrography,paleoflow analysis,and detrital zircon U-Pb geochronology analysis,combined with previously reported data,the lithofacies and paleogeographic characteristics of the Middle-Late Triassic sandstone and detrital zircon age spectrum in the Yanyuan Basin show differences,revealing different provenance systems:during the Middle Triassic Ladinian to Late Triassic Carnian,the sedimentation in the Yanyuan Basin was mainly influenced by the overall uplift of the western Yangtze Plate,indicating an internal provenance from the Yangtze Plate;while during the Late Triassic Norian,the basin began to receive material from the western Qiangtang multi-arc basin system,reflecting the influence of the western Sanjiang orogenic belt on the formation of the Yanyuan Basin,and marking the commencement of the comprehensive basin-mountain transformation process in the western Yangtze region.