华南南雄盆地晚白垩世一古近纪红层的物源演化对区域构造体制转换的启示

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[分类号]P595；P597 [文献标志码］A

Abstract：The south China Block underwent intracontinental extension during the late Mesozoic driven by adjustments inthe subduction angleof the paleo-Pacific plate，resulting in aseries of northeast-southwest trending extensional basins，exemplified by Nanxiong Basin.These basins are characterized by terrgenous clastic strata that recorded provenance changes driven byregional tectonic activities.To investigate the geochemical characteristics and provenance of sediments from the Cretaceous to Paleogene in Nanxiong Basin，systematic sampling was conducted forthe Zhenshui，Shanghu，andNongshanFormations intheLuofuzhai andEjingling sections of the basin.Atotalof 14 sandstone and mudstone samples were analyzed for majorand trace elements，and three samples were examined for detrital zircon U-Pb ages and Lu-Hf isotopes.The whole-rock geochemical data reveal that the Zhenshui Formation was primarily sourced from felsic igneous rocks，and the Shanghu Formation was alsodominated by felsic igneous sources，but withanincreasing contribution from ancient metamorphosed sedimentaryrocks.The Nongshan Formation exhibits a more diverse provenance，with a continued dominance of felsic igneous material mixed with mafic components.The detrital zircon U-Pbagesand Hf isotopic data indicate thatthe Zhenshui Formation primarily derives from Indosinian Qingzhangshangranite plutons to the south ofNanxiong Basin，while theShanghuFormation was sourced from Caledonian granite plutons to the north and Precambrian ancient clastic rocks of the Cathaysia block.The NongshanFormation，however，is mainly sourced from Caledonianand Indosinian granite bodiesalong the basin's periphery，with Cathaysia ancient clastic rocks representing only a minor source.The provenance change suggests a tectonic regime transition in Nanxiong Basin during the late Cretaceous to early Paleogene， from extension to compresson.Subsequently， the compressional tectonic activity weakened during the deposition of the Nongshan Formation.

Key words： Nanxiong Basin； provenance analysis； sedimentary geochemistry； detrital zircon geochronology;late Cretaceous-Paleogene

华南陆块由扬子陆块和华夏陆块沿江南造山带在新元古代拼合而成（舒良树，2012；林伟等，2024）。（剩余34440字）