Isotopic Helium as an Indicator of the Terestrial Exposure Age of Minerals and Implications for Surface Processes

3 He在暴露在地表的矿物质中积累 因为宇宙射线会使较小的原子核从 靶核。 因为宇宙射线的通量和产生 速率受到很好的限制，宇宙起源部分 矿物中3 He的测定， 4地球表面丰富的矿物可以用来 来计算矿物的暴露年龄 这些知识可以 可以用来研究在地球上发生的各种过程， 从100年到几百万年 年 测量涉及岩石中的3 He和4 He丰度 其暴露年龄受到地质条件的限制 证据和常规的K-Ar或14 C测年方法。 样品将从冰川表面（Sierras）取芯， 近期熔岩流（W.美国，夏威夷）。 在斯克里普斯 同位素实验室，研究人员将测试放射性气体 分离技术和氖的可能功效， 放射成因年代测定 了解表面的暴露年龄， 第四纪地层学的重要应用， 地貌学，研究化学和机械侵蚀 率，并可能有应用程序，以了解地震 反复无常和其他群众运动现象。

3He accumulates in minerals exposed at the earth's surface because cosmic rays cause spallation of smaller nuclei from target nuclei. Because the cosmic ray flux and production rates are fairly well constrained and the cosmogonic component of 3He in minerals can be determined, measurement of 3He and 4He abundances in minerals at the earth's surface can be used to calculate the exposure ages of minerals. This knowledge can be used to study a variety of processes that take place at the earth's surface on a time scale of 100 years to several million years. Measurements involve the 3He and 4He abundances in rocks whose exposure ages are fairly well constrained by geologic evidence and by conventional K-Ar or 14C dating methods. Samples will be cored from glaciated surfaces (Sierras) and recent Lava flows (W. United States, Hawaii). In the Scripps Isotopic Laboratory, researchers will test radiogenic gas separation techniques and the possible efficacy of neon for radiogenic dating. Knowledge of the exposure age of surfaces will have important applications in Quaternary stratigraphy and geomorphology, in the study of chemical and mechanical erosion rates, and may have applications to understanding seismic recurrences and other mass movement phenomena.