宇宙成因核素在地球科学中的应用

APPLICATIONS OF COSMOGENIC NUCLIDES IN THE EARTH SCIENCES

随着加速器质谱的出现 ,宇宙成因核素展示了其在地球科学中的生命力。文中介绍了宇宙成因核素的生成、示踪原理及近些年来在地球科学中的应用 ,特别着重地介绍了原地生成宇宙成因核素定年这一新的技术。宇宙成因核素是宇宙射线粒子 (包括原生和次生粒子 )与大气及岩石发生核反应所生成的新的核素 ,其在大气及岩石中的生成量可用已知物理过程定量地描述。大气生成宇宙成因核素在考古、古环境及地球各圈层的相互作用方面得到了广泛的应用 ,原地生成宇宙成因核素则在地貌学研究中扮演着重要的角色 ,成为一门新的实验技术。这门技术可以定量地描述地表的暴露历史和侵蚀速率 。

The measurement of long lived radioisotopes produced by cosmic ray in terrestrial samples has been facilitated by the development of the Accelerator Mass Spectrometry (AMS) in the 80s. This paper introduces the formation mechanism of cosmogenic nuclides, the theoretical background of their quantification, and the applications of cosmogenic nuclides in the earth sciences in recent years. A large effort is focused on the introduction of a new dating technique using the cosmogenic nuclides produced in situ. Cosmogenic nuclides are produced by interaction of cosmic ray particles (including original and secondary) with atmosphere and rock materials. The production of cosmogenic nuclides in the atmosphere and the Earth's surface can be quantified with well known physical processes. 14 C,a cosmogenic nuclide, is widely applied in archeology; and other cosmogenic nuclides produced in the atmosphere are used in the study of paleoclimate and the evolution of the outer layers of the Earth-the atmosphere, the oceans, the cryosphere, and the lithosphere.As a new dating technique, the cosmogenic nuclides produced in situ play significant roles in geomorphic research. This technique, by quantifying exposure ages and erosion rates of Earth's surface, becomes a unique tool in solving many geological problems.