金沙江巧家段干热河谷黄土状物质风成成因的微形态证据  

Evidence of micromorphological for eolian origin of loess-like materials in the dry-hot valley of Qiaojia section,Jinsha River

作　　者：张殷豪 苏怀[1] 董铭[1] ZHANG Yinhao;SU Huai;DONG Ming(Faculty of Geography,Yunnan Normal University,Kunming 650500,China)

机构地区：[1]云南师范大学地理学部,昆明650500

出　　处：《第四纪研究》2025年第1期25-33,共9页Quaternary Sciences

基　　金：云南省科技人才与平台计划项目(批准号:202305AC160086);国家自然科学基金项目(批准号:42262024)共同资助。

摘　　要：金沙江巧家段干热河谷分布有一定规模的黄土状物质,尽管前人从宏观岩性特征和粒度分析的角度推测它可能是风成成因,但还缺乏微形态方面的研究。本研究通过注胶切片-偏光显微观察和石英颗粒扫描电镜图像分析的方法对比了巧家晚更新世黄土状物质(厚度约0.5 m)与典型风成沉积物(兰州九州台马兰黄土)和典型水成沉积物(昔格达组湖相沉积物)间的差异,发现巧家黄土状物质与九州台马兰黄土在微形态结构上十分相似,它们都具有典型的支架孔隙结构,碎屑颗粒多呈点状接触和支架排列,且常有淀积胶膜包裹和团粒状集粒相伴,石英颗粒表面具有碟形坑、麻坑、新月形撞击坑、弯曲脊、裂纹等结构,而水成成因的昔格达组湖相沉积物则完全没有这些特征。这一研究结果为巧家黄土状物质的风成学说补充了微形态学方面的证据。There are a certain scale loess-like materials distributed in the dry-hot valley of Qiaojia section,Jinsha River.Although predecessors supposed that it may be eolian origin by perspective of macroscopic lithologic characteristics and grain size,the micromorphological research is still deficiency.In order to perfect its eolian theory,this article employed the methods of gelatinous slicing and polarized light microscope observation,as well as analysis of quartz particles by scanning electron microscope images,to compare the differences between the Qiaojia loess-like materials and typical eolian deposit and typical aqueous deposit.The Qiaojia loess-like materials for comparison was collected from the Huatan area on the west side of the Qiaojia section,Jinsha River Valley(26°54'20.47″N,102°52'25.88″E;No obvious bedding,at least three layers of paleosols can be identified;Consists mainly of silty sand;Sampling stratum thickness about 0.5 m;Age of deposition is Late Pleistocene).The typical eolian deposit was collected from the Malan loess in Lanzhou Jiuzhoutai(36°05'51.92″N,103°47'35.36″E;Consists mainly of silty sand;Sampling stratum maximum thickness over 50 m;Age of deposition is Late Pleistocene).And the typical aqueous deposit was collected from the lacustrine sediments in Xigeda Formation,Panzhihua(26°33'09.51″N,101°56'21.57″E;Consists mainly of silty sand and clay;Sampling stratum thickness about 1.3 m;Age of deposition is Late Pleistocene).It is found that Qiaojia loess-like materials and Jiuzhoutai Malan loess are very similar in the micromorphology.They both have typical scaffold pore,and most of these clastic particles has characteristics of point contact and support arrangement,which are often wrapped by deposition coating and accompanied by aggregates.However,the lacustrine sediments of Xigeda Formation do not have these characteristics at all.The surface textures of quartz particles of Qiaojia loess-like materials and Jiuzhoutai Malan loess both has dish-shaped pits,pockmarked pits,cres

关 键 词：金沙江巧家段 黄土状物质 微形态 

分 类 号：P534.63[天文地球—第四纪地质学] P512.21[天文地球—古生物学与地层学]