GRGC: Geologic and Glaciologic Records Inferred from Cosmic Ray Produced Neon at the Earth's Surface

9406016马蒂在过去的几年里，在地球表面物质中发现了几种宇宙射线产生的放射性核素(10Be、14C、26Al、36Cl)以及稳定的核素3He、21Ne和22Ne。其中一些核素现在被用作地球物理和地质现象研究的示踪剂，开辟了一个新的研究领域，可望提供有关全球变化研究中变化速度的基本数据。这样的研究需要准确的生产率，无论是现在还是过去，而这一点目前还无法获得。我们正在使用一种直接方法，通过在山区暴露相关目标来确定目前的一些生产率。此外，我们正在通过对104-1047a照射1h的样品中Ne的同位素测量，来评估宇宙线产生的核素21Ne和26Al的产额比P21/P26。我们的实验数据与600 MeV质子辐照实验中推断的中子反应是一致的(Aylmer等人，1987)，但与理论预测不一致。3He21Ne比值的测量表明，3He不完全保留在石英中。因此，预计21Ne产生率和准确的21Ne 10Be和21Ne/26Al产生率比率将为评估侵蚀率和确定地质过程(抬升、冰盖变化等)提供必要的信息。还需要进一步的校准，例如长期保留NEC的活化能，但我们现在已经准备好研究全球变化问题。我们建议研究南极冰场(海平面的主要控制单位)的长期暴露历史。我们计划评估Allan Hills地区记录的岩石的石英分离中的21Ne记录，并研究冰场附近的一个剖面，在那里测量到放射性核素26Al和10Be(Nishiizumi等人，1991年)。这些作者估计，该地区的岩石可能在没有冰盖的情况下暴露了数百万年，但警告说，需要积累稳定的核素记录来确定早期历史。我们还计划包括来自同一地区的样本，这些样本表明了非常严重的侵蚀速度。其目的是增加受“侵蚀平衡”限制的宇宙线曝光的记录时间间隔。

9406016 Marti In the last few years, several cosmic ray produced radionuclides (10Be, 14C, 26Al, 36Cl), as well as stable nuclides 3He, 21Ne and 22Ne have been discovered in terrestrial surface materials. Some of these nuclides are now employed as tracers in studies of geophysical and geological phenomena and open up a new field of study that is expected to provide essential data on rates of change in global change research. Such studies require accurate production rates, present and past, which are not currently available . We are using a direct method for the determination of some present production rates by exposing relevant targets at mountain altitudes. Furthermore, we are evaluating the production rate ratio P21/P26 of the cosmic ray produced nuclides 21Ne and 26Al by isotopic measurements of Ne in samples whic1h were exposed for 104-1047a. Our experimental data are consistent with inferred neutron reactions in a 600 MeV proton irradiation experiment (Aylmer et al., 1987), but do not agree with theoretical predictions. Measurements of the 3He21Ne ratio show that 3He is incompletely retained in quartz. Therefore, 21Ne production rates and accurate 21Ne10Be and 21Ne/26Al production rate ratios are expected to provide essential information for the evaluation of erosion rates and to define geological processes (uplift, variations in ice cover, etc.) Further calibrations, such as activation energies for long-term retention of Nec, are still required, but we are now ready for research on global change issues. We propose to study the long-term exposure history of the Antarctic ice field (the major controlling unit of the sea level). We plan to evaluate the 21Ne records in quartz separates of documented rocks from the Allan Hills region and to study a section adjacent to the ice field in which the radionuclides 26Al and 10Be were measured (Nishiizumi et al., 1991). These authors estimate that rocks in this region may have been exposed for millio ns of years without ice cover, but caution that the record of an integrating stable nuclide is required to define the early history. We plan to also include samples from the same area which indicate very erosion rates. The purpose is to increase the recorded time interval of cosmic ray exposure which is limited by the "erosion equilibrium".