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The SPICE Project: The SP Flow Production-Rate Inter-Calibration Site for Cosmogenic-Nuclide Evaluations

SPICE 项目：用于宇宙成因核素评估的 SP 流生产率相互校准站点

基本信息

批准号：
244559995
负责人：
Professor Dr. Tibor J. Dunai, since 8/2016
金额：
--
依托单位：
Institut für Geologie und Mineralogie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/244559995?language=en
关键词：
SPICE Project SP Flow Production

项目摘要

Our proposed SPICE project will measure, for the first time and at one calibration site, accurate cross-calibrated production rates of each of the most commonly used cosmogenic nuclides (He-3, Be-10, C-14, Ne-21, Al-26, and Cl-36) integrated over the past 72 ka. The formally named SP Flow is a quartz-, olivine- and pyroxene-bearing basalt with an Ar-40/Ar-39age of 72. We are not aware of any other location worldwide where these minerals coexist in an uneroded, well-dated lava flow. The flow is preserved in the arid desert climate of northern Arizona, USA, and its unweathered appearance and the lack of soil development indicate it has undergone negligible erosion. Preliminary He-3 and Ne-21 data in pyroxene from the SP flow are consistent with a 72 ka eruption age and yield production rates (with 7 percent uncertainty) in excellent agreement with other rates reported in recent literature. The uncertainties are low due to the high-precision Ar-40/Ar-39 age.The SPICE Project will increase the accuracy of six cosmogenic nuclide production rates, and thus, will impact every published study, as well as future studies that use cosmogenic nuclides to quantify earth-surface processes. Cosmogenic nuclides have revolutionized Quaternary geology by allowing us to quantify large-scale, long-term (Myr time-scale) landscape evolution, as well as the generation and movement of sediment through drainage systems. Scientists also use cosmogenic nuclides to date glacial moraines, debris flows, landslides, lava flows, and fluvial deposits all over the world. The Quaternary science community has used this technique to study global climate change (e.g., in the Northern and Southern Hemispheres) and to assess links between climate regimes and landscape evolution. Nearly all Quaternary paleoclimate synthesis studies make use of glacial geology/chronology studies, and most of them rely in large part on cosmogenic nuclide data. Exposure-age data have contributed significantly to the climate-change debate, and exposure ages are often compared to other Quaternary age-dating methods in global-climate studies. The majority of glacial-climate scientists strive to correlate exposure-dated moraines in their own research projects with each other or with independently dated (i.e., radiocarbon, U-series, OSL, etc.) climate events at millennial time scales; however, these scientists make inferences about these correlations that are simply not justifiable when uncertainties in the absolute values of nuclide production rates and in production-rate scaling are currently estimated at 10 to 15 percent. Though impressive progress has been made over the past 20 years in determining cosmogenic nuclide production rates and improving scaling schemes, research is still needed to minimize these uncertainties to less than 5 percent. The SPICE project puts us one step closer to obtaining this lower uncertainty.

我们拟议的SPICE项目将首次在一个校准地点测量过去72 ka期间整合的每一种最常用的宇宙核素(He-3、Be-10、C-14、Ne-21、Al-26和Cl-36)的准确交叉校准产生率。正式命名的SP流是一种含石英、橄榄石和辉石的玄武岩，其Ar-40/Ar-39年龄为72。据我们所知，世界上没有任何其他地方这些矿物共存于未受侵蚀的、测年准确的熔岩流中。这条河流保存在美国亚利桑那州北部干旱的沙漠气候中，它未经风化的外观和缺乏土壤发育表明它经历了可以忽略不计的侵蚀。来自SP流的辉石中He-3和Ne-21的初步数据与72ka喷发年龄和产量产率(7%的不确定度)一致，与最近文献中报道的其他产率非常一致。由于高精度的Ar-40/Ar-39年龄，不确定度很低。SPICE项目将提高六种宇宙核素产生率的准确性，因此将影响每一项已发表的研究，以及未来使用宇宙核素量化地球表面过程的研究。宇宙成因核素使我们能够量化大规模、长期(MyR时间尺度)的地貌演变，以及通过排水系统产生和移动的沉积物，从而使第四纪地质学发生了革命性的变化。科学家们还使用宇宙成因的核素来测定世界各地的冰川冰川、泥石流、山体滑坡、熔岩流和河流沉积的年龄。第四纪科学界利用这项技术研究全球气候变化(例如，在北半球和南半球)，并评估气候制度与景观演变之间的联系。几乎所有的第四纪古气候综合研究都利用了冰川地质学/年代学研究，其中大多数在很大程度上依赖于宇宙成因核素数据。暴露年龄数据对气候变化的辩论做出了重大贡献，在全球气候研究中，暴露年龄经常被与其他第四纪年龄测定方法进行比较。大多数冰川气候科学家努力在他们自己的研究项目中将暴露年代的冰雹相互关联或与独立的年代(即放射性碳、U系列、OSL等)相关联。然而，当核素产生率绝对值和产生率比例的不确定度目前估计为10%至15%时，这些科学家对这些相关性做出的推断是完全没有道理的。尽管在过去20年里，在确定宇宙核素产生率和改进比例计划方面取得了令人印象深刻的进展，但仍需要研究将这些不确定因素降至5%以下。SPICE项目让我们离获得更低的不确定性又近了一步。