地质学报2025，Vol.99Issue(7)：2189-2202,14.DOI:10.19762/j.cnki.dizhixuebao.2024027
湘南晚白垩世风成砂岩及其环境气候意义
Late Cretaceous eolian sandstones in southern Hunan Province:Indicative of paleo-environment and climate
摘要
Abstract
Eolian sandstones serve as valuable climatic proxies in paleoclimatic analyses.However,for the Late Cretaceous eolian sandstones in South China,studies on lithofacies,paleoclimatic indicators,and paleowind systems remain limited and debated.This study integrates lithofacies,texture,and paleowind direction analyses of eolianites from the Honghuatao Formation in the Changsha,Li-You,and Cha-Zi basins of middle-southern Hunan.Our results reveal reddish and yellowish-orange sandstones characterized by large,high-angle cross-bedding.Laminal sets are often 3～10 m thick,reaching up to～20 m.Fine sand dominates the detrital grains,exhibiting medium to good roundness and sorting.Reddish-brown and/or dark-brown Fe-varnish commonly coats quartz edges,while dish-,V-,and crescent-shaped impact scars are prevalent on quartz surfaces.The sandstones display grain-supported and Fe-mud matrix textures,with reactivation(R),interdune migration(I),and superimposition(S)surfaces bounding the dunes.These features collectively indicate that the sandstones of the Honghuatao Formation are of eolian origin.These eolianites were deposited atop the underlying Luojingtan alluvial fan conglomerates,with both lithofacies laterally interfingering.The alluvial fan lithofacies is characterized by pulse debris and muddy gravity current sediments,indicative of an arid alluvial environment.The coexistence of eolian sandstones and arid alluvial fan lithofacies suggests a(semi-)arid climate,possibly under relatively cool conditions.The limited basin distribution and association with proximal-source alluvial fan facies indicate that Late Cretaceous eolian sandstones accumulated in an intermontane dune environment rather than in a sand-sea desert.Two dominant sets of paleowind directions,SE and NE,are recognized from the eolian sandstones.These directions are inconsistent with modern planetary wind systems.We propose that these two sets of prevailing wind directions may represent a superposition of imprints from modern planetary,East Asian monsoon,and local reflection-refraction wind systems.关键词
古气候/古环境/风成沙丘/古风系/晚白垩世/湖南Key words
paleoenvironment/paleoclimate/paleowind system/Late Cretaceous/Hunan引用本文复制引用
李祥辉,王旌羽,郑辰予,刘芮岑..湘南晚白垩世风成砂岩及其环境气候意义[J].地质学报,2025,99(7):2189-2202,14.基金项目
本文为国家自然科学基金项目(编号42172106,41372106)资助的成果. （编号42172106,41372106）
