我国广西壮族自治区是世界喀斯特地貌分布最广、类型最全的区域之一，天坑是喀斯特地区特有的地貌形态，对喀斯特地貌及演化的研究具有重要意义。原地宇生核素在地表岩石中的积累与岩石样品在地表的暴露时间和侵蚀速率的大小有关，利用长寿命的放射性核素可以对几千年到百万年间的暴露年龄和侵蚀速率进行测定。喀斯特地区岩石的主要成分是碳酸钙，钙是宇宙射线产生长寿命放射性核素Cl-36的主要靶元素，Cl-36 能在岩石中快速产生并积累成为测定灰岩暴露年龄和侵蚀速率的理想核素。本工作将利用高灵敏的加速器质谱技术测定岩石中原地宇生核素Cl-36含量来研究广西乐业大石围天坑的暴露年龄，从而为研究大石围天坑的形成、演化以及此地区新构造抬升速率、古气候及地质环境演变等提供基础数据和研究方法，从而进一步为研究中国隆升带地质构造，南亚次大陆与亚欧板块的作用，以及喜马拉雅山脉及青藏高原的形成过程提供研究基础。

Guangxi Zhuang Autonomous Region in southern China is one of the most typical karst relief areas with various forms. Tiankeng is a typical Karst relief of Late Quaternary Period, which plays an important role in researching the surface shape and evolution of the Karst relief. The concentration of in-situ Cl-36 in the surface rock is depended on the exposure time and erosion rate of the rock. The exposure age and erosion rate can be measured by long half-life radionuclide in a timescale from thousands years to million years. The main component of the rock of Karst relief is calcium carbonate, and Ca-40 is the target element by fast cosmic ray reaction to produce Cl-36. Cl-36 is the ideal radionuclide to measure the erosion rate and exposure time of limestone, for it’s high production rate and fast accumulation. This study is the first application of 36Cl measurements with exposure dating for karst Tiankeng samples of carbonate rocks (calcite) from Da Shiwei Tiankeng, Leye County, Guangxi. The purpose of this work is provide the basic data and research methods for investigating the formation, evolution, local tectonic uplift rates of Da Shiwei Tiankeng, and then for the further researches of Chinese uplift belt, the collisions between the South Asian Subcontinent and the Eurasian plate, and the formation of the Himalayas and the Tibetain Plateau.