贵州荔波黑洞碎屑沉积物宇宙成因核素^(26)Al/^(10)Be埋藏年龄  

COSMOGENIC NUCLIDES ^(26)Al AND ^(10)Be BURIAL AGE OF BLACK CAVE SEDIMENTS,LIBO OF GUIZHOU,CHINA

作　　者：刘彧[1,2] 王世杰[1,3] 刘秀明[1,3] 徐胜 Derek Fabel 罗维均[1,3] 

机构地区：[1]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002 [2]中国科学院大学,北京100049 [3]中国科学院普定喀斯特生态系统观测研究站,普定562100 [4]Scottish Universities Environmental Research Centre,East Kilbride,G750 QF,UK [5]Department of Earth Science and Geography,University of Glasgow,Glasgow,G12 8QQ,UK

出　　处：《第四纪研究》2013年第3期437-444,共8页Quaternary Sciences

基　　金：中国科学院战略性先导科技专项项目(批准号:XDA05070400);中国科学院知识创新工程方向性项目(批准号:KZCX2-YW-306);国家重点基础研究发展规划项目(973项目)(批准号:2006CB403200)共同资助

摘　　要：河流下切在岩溶区形成的多级层状洞穴,记录了地体隆升和地貌演化历史,但由于测年手段的限制,国内在这方面的研究一直进展不大。近年来,运用宇宙成因核素得到洞穴碎屑沉积物埋藏年龄的方法,已成为反演山地区域构造-地貌演化的新途径。本文尝试运用宇宙成因核素^(26)Al/^(10)Be埋藏测年技术,对属于贵州荔波地区4层洞穴系统的黑洞(第二层)碎屑沉积物进行年龄测定,假设样品进洞前无埋藏史,测年结果显示黑洞年龄至少有1.06±0.23Ma,并且该地区三岔河流域的侵蚀速率为55.1±2.3m/Ma。这是对该地区洞穴测年的一次新探索,体现出洞穴沉积物宇宙成因核素埋藏测年技术在我国晚新生代地质地貌演化研究方面具有良好的应用前景。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 w

关 键 词：26A1 10Be 埋藏测年 黑洞 贵州荔波 

分 类 号：P597.3[天文地球—地球化学] P931.5[天文地球—地质学]