Collaborative Research: RUI: Application of In-situ Produced Cosmogenic 36Cl to Central Andean Volcanism

9523565 de Silva最近，对地貌学领域的一个重要贡献是开发了一种用于量化地质表面侵蚀速率和暴露年龄的核方法。 该方法依赖于对暴露于宇宙射线的岩石中原位不断产生的大量放射性核素和稳定核素的测量。 我们选择检查36 Cl是因为它易于测量和适用于火山岩。 我们建议校准36 Cl方法的暴露年龄追溯到 六百卡。 然后将36 Cl和40 Ar/39 Ar方法应用于中安第斯山脉火山岩，以提供中安第斯山脉晚更新世至全新世火山活动的年代学框架。 选择中部安第斯山脉进行这项试点研究，是因为它可能是世界上大陆火山活动最好的例子，其高海拔和极端干旱的环境使火山特征得到极好的保存（侵蚀率极低）。 此外，由于在高海拔地区获得高宇宙射线入射通量，宇宙成因同位素的生产率也将很高。 将确定36 Cl深度剖面，如果可能的话，还将确定36 Cl/10 Be比率，以确保侵蚀率远低于影响暴露年龄的侵蚀率。 拟议中的研究将有助于量化有关中部安第斯山脉火山活动的几个重要科学问题：（1）火山结构的增长和演变速度，（2）熔岩流的喷发频率和岩浆生产率，以及（3）36 Cl暴露年龄和侵蚀率与陆地卫星成像数据的相关性。 这项研究很重要，因为火山作用和构造作用密切相关，关于研究过程的任何结论都可能适用于全球。

9523565 de Silva Recently an important contribution to the field of geomorphology has been the development of a nuclear method for quantifying erosion rates and exposure ages of geological surfaces. the method relies on measurement of a number of radionuclides and stable nuclides which are continually being produced in situ in rocks exposed to cosmic rays. We have chosen to examine 36Cl due to its ease of measurement and applicability to volcanic rocks. We propose to calibrate the 36Cl method of exposure age dating up to 600 Ka. The 36Cl and 40Ar/39Ar methods will then be applied to Central Andes volcanic rocks to provide a chronological framework for late Pleistocene to Holocene volcanism in the Central Andes. The Central Andes has been selected for this pilot study because it is probably the finest example of continental volcanism in the world, and its high elevation and hyper-arid environment result in superb preservation (extremely low erosion rates) of volcanic features. In addition, since a high incident flux of cosmic rays is attained at high altitudes, cosmogenic isotope production rates will also be high. 36Cl depth profiles, and, if possible, 36Cl/10Be ratios will be determined to ensure that the erosion rate is well below that which would affect exposure ages. The proposed study will help to quantify several important scientific questions about central Andes volcanism: (1) the rate of growth and evolution of volcanic constructs, (2) the eruption frequency of lava flows and magma production rates, and (3) the correlation of 36Cl exposure ages and erosion rates with Landsat imaging data. The study is important as volcanism and tectonism are intimately related and any conclusions about the processes studied will likely be applicable globally.