Provenance of Early Triassic Clastic Rocks and Its Constraint on Tectonic Evolution of Lijiang Basin,Upper Yangtze Block
Zhu Min
Meng Lifeng
Li Ye
Chen Xinwei
Wu Hongxiang
Abstract：Lijiang basin is a multi-plate confluence zone located in the southwestern margin of the Yangtze block.The study for the provenance of the Lower Triassic reveals the source-sink system of the southwestern Yangtze block and its spatio-temporal relationship with the western Gondwana arc basin system.Field observations and microscopic identification show that the sandstones of the Lamei Formation in Heqing region are mainly derived from the proximal transport of felsic volcanic rocks.The detrital zircons exhibit single age peaks of～254 Ma and～255 Ma,corresponding to the timing of felsic magmatic activity in the Emeishan Large Igneous Province(ELIP),and are consistent with interior/non-orogenic magmatic zircon trace element signatures,distinguishing them from those in arc orogenic belts.The εHf(t)values of the Lu-Hf isotopic analysis indicate the provenance of the sandstones of Lamei Formation are from the felsic rocks of the ELIP.Whole-rock geochemical data show that the Lamei Formation shares similar trace element characteristics with the Emeishan rhyolites,porphyries and syenites.A comprehensive analysis suggests that the materials of the Lamei Formation originate from the proximal transport of rhyolite,trachyte and syenite from ELIP.During the Early Triassic,the Lijiang basin functioned as a passive continental margin sedimentation area,primarily receiving materials from the ELIP,with no contributions from the western arc-basin system.
Keywords：Lower TriassicLijiang basinprovenance analysisdetrital zircon U-Pb agechronologywhole-rock geochemistryLu-Hfisotope
Publication Date：2025-11-30
Online Publishing Date：2025-12-15(First online date of this platform, not the publication date of the document)
Pages：18( 4424-4441 )