• 责任者：Liu Yu (State Key Laboratory of Environmental Geochemistry ; Institute of Geochemistry ; Chinese Academy of Sciences ; Guiyang 550002 ; China) ; Wang Shijie
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(3)
• 关键词：洞穴沉积 ; cave deposit ; 宇宙成因核素测年 ; cosmogenic nuclide dating ; 贵州 ; Guizhou Province
• 页码：p.437-444
• 图表：illus., 1 table, 38 refs.
• 分类号：1400
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

We report the first cosmogenic nuclide burial age in Black Cave sediments from Libo at the southeastern margin of the Guizhou Plateau, SW China. For half a century,the landscape evolution of Guizhou during the Late Cenozoic has been a much debated topic in the Earth sciences due to poorly preserved surface materials and unsuitable dating methods. River downcutting in the karst area forms an abundance of multilevel caves,and provides an opportunity to integrate the cosmogenic 26Al/10Be burial dating method to determine the incision history of the river. It has been a new approach to invert the geological and landscape evolution of mountainous region in these years,by determining the cosmogenic nuclides concentrations in cave clastic sediments. There developed four level caves in Libo, and they could correspond with the fluvial terraces and deplanation surfaces. In general, the caves of altitude 800 -900m （ IV ） are the highest level caves in this area, the cave passages at 650 - 700m （ III ） are the third level, the cave passages at 520-580m（ II ） are the second level. These cave levels are hydrologically abandoned and above the modern flood zone. The cave passages under 500m（ I ） are hydrologically active and still within the modern flood zone. The Black Cave（25°18. 850＇N, 108°02. 821＇E） is located in the lkm east of Mogen Village of Dongtang, which belongs to Libo of Guizhou Province （Fig. l d）. This cave is developed in the upper carboniferous limestones,the length of cave is approximately 250m, and the altitude of cave entrance is approximately 608 （ ±5 ） m, which belongs to the second level cave of Libo. One quartz pebbles sample is collected from the section at the left side of the channel and away from the entrance about 80m. The pebbles are consist of limestone, sandstone and mudstone,and good cemented by the argillo-arenaceous materials. The size of sample pebbles are approximately 1 - 5cm with rounded edge,the grain size of quartz is approximately 0.25 ~ 0.50mm and washed into the cave from the outside Permian stratums obviously. Physical preparation,including extraction and purification from bulk samples by magnetic and density separation, were performed at the State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences. Chemical treatments, AMS measurements and stable A1 measurements were all performed at the laboratory of Scottish Universities Environmental Research Centre. The first cosmogenic 26A1/l~Be burial dating results indicate that the age of Black Cave is 1.06_＋0.23Ma at least（ assume the sample have no pre-burial history）,and the pre-burial erosion rate of sample is 55.1_＋2.3m/Ma. This is a new exploration of cave dating in this area,and it also shows a well foreground in the studies of Late Cenozoic landscape evolution in our country by eosmogenic nuclides dating method in cave sediments.