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

合作研究：RUI：原位产生的宇宙成因 36Cl 在安第斯山脉中部火山活动中的应用

• 批准号: 9523565
• 负责人: Shanaka de Silva
• 金额: $ 4.5万
• 依托单位: Indiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-07-01 至 1997-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9523565&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Application; situ

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.

9523565德席尔瓦最近对地貌学领域的一项重要贡献是发展了一种核方法，用于量化地质表面的侵蚀速度和暴露年龄。该方法依赖于对大量放射性核素和稳定核素的测量，这些放射性核素和稳定核素在暴露于宇宙射线的岩石中不断在原位产生。我们之所以选择检测36Cl，是因为它易于测量，而且适用于火山岩。我们建议校准~(36)Cl暴露年龄至600kA的方法。然后，36Cl和40Ar/39Ar方法将被应用于中央安第斯火山岩，以提供中央安第斯山脉晚更新世至全新世火山活动的年代学框架。之所以选择中央安第斯山脉进行这项初步研究，是因为它可能是世界上大陆火山活动的最好例子，其高海拔和极度干旱的环境导致火山地貌得到了极好的保存(极低的侵蚀率)。此外，由于宇宙射线的高入射通量在高海拔地区获得，宇宙成因的同位素产生率也将很高。将确定36Cl深度分布，并在可能的情况下确定36Cl/10Be的比率，以确保侵蚀速度远低于影响暴露年龄的比率。这项拟议的研究将有助于量化有关安第斯山脉中部火山活动的几个重要科学问题：(1)火山构造的生长和演化速度，(2)熔岩流的喷发频率和岩浆产生速度，(3)36Cl暴露年龄和侵蚀速度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，关于所研究过程的任何结论都可能适用于全球。