Quantifying basalt denudation rates and their contribution to the global carbon dioxide budget using cosmogenic Mn-53

使用宇宙成因 Mn-53 量化玄武岩剥蚀率及其对全球二氧化碳预算的贡献

• 批准号: 339625557
• 负责人: Dr. Steven Binnie
• 金额: --
• 依托单位: Scottish Universities Enviromental Research Centre (SUERC)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/339625557?language=en
• 关键词: Quantifying; basalt; denudation; rates; their

Chemical weathering of silicate rocks at the Earth's surface consumes atmospheric carbon dioxide and thus has the potential to influence global climate. In particular, the weathering of basalt rocks could be an important sink for carbon dioxide. Our understanding of what controls the chemical weathering rates of rocks has been limited by our inability to measure rates over the timescales that are relevant to land-forming processes. During the last two decades this situation has improved due to the development of terrestrial cosmogenic nuclide techniques, able to quantify denudation and thus extract rates of chemical weathering over millennial timescales and longer. Basaltic terrains have received little attention in this work, due in part to a lack of suitable target elements for cosmogenic nuclide measurements. However, recent progress has shown cosmogenic Mn-53 is able to quantify denudation rates in iron oxides, which means that it can be measured in basalt. Our overall aim is to take advantage of this new ability and to quantify the importance of basalt weathering as a global atmospheric carbon dioxide sink. To achieve this we will collect samples from two climatically diverse environments: the Paraná flood basalts in humid southern Brazil and the Etendeka flood basalts in arid Namibia. These rocks were originally extruded as one body but were split in two and separated due to the opening of the Atlantic Ocean. While they are lithologically the same, they experience very different amounts of precipitation and both are affected by dramatic temperature gradients. Cosmogenic Mn-53 concentrations in the rock samples will reveal rates of denudation and subsequently the influence that climatic factors have on rates of weathering. Additional investigations into the relationships between chemical and physical weathering, coupled with rates of denudation from nearby non-basaltic lithologies, will allow us to develop a broad understanding of the rates at which basalt weathers and the factors that control theserates.

地球表面有机硅岩的化学风化会消耗大气二氧化碳，因此有可能影响全球气候。特别是，玄武岩的风化可能是二氧化碳的重要水槽。我们对控制岩石化学风化速率的理解受到了我们无法衡量与土地形成过程相关的时间标准的速率的限制。在过去的二十年中，由于陆地宇宙基因核素技术的发展，这种情况有所改善，能够量化剥离，从而在千禧年的时间标准中提取化学风化的速率，并且更长。玄武岩地形在这项工作中很少受到关注，部分原因是缺乏适合宇宙核素测量值的目标元素。但是，最近的进展表明宇宙基因的MN-53能够量化氧化铁中的剥离率，这意味着它可以在玄武岩中进行测量。我们的总体目的是利用这一新能力，并量化玄武岩风化为全球大气二氧化碳水槽的重要性。为了实现这一目标，我们将从两个气候多样的环境中收集样品：巴西潮湿的巴拉纳洪水玄武岩和干旱纳米比亚的Etendeka洪水盆地。这些岩石最初被挤出为一个尸体，但由于大西洋的开放而被分开并分开。尽管它们在岩性上相同，但它们的降水量量非常不同，并且都受到急剧温度梯度的影响。岩石样品中的宇宙MN-53浓度将揭示剥离的速率，并随后气候因素对风化速率的影响。对化学风化和物理风化之间的关系的进一步研究，再加上附近的非巴塞尔特岩性的剥离率，将使我们能够对玄武岩晶体机和控制这些底层的因素的速率有广泛的了解。