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Sediment production in large river basins throughout the Quarternary

第四纪大河流域的产沙量

基本信息

批准号：
210713946
负责人：
Dr. Hella Wittmann-Oelze
金额：
--
依托单位：
Fachrichtung Geochemie, Hydrogeologie, Mineralogie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/210713946?language=en
关键词：
Sediment production large river basins

项目摘要

Late‐Cenozoic global cooling has been suggested to be associated with a global increase in sedimentation rates, which is interpreted to be due to an increase in mountain erosion rates. Both enhanced mountain building and changes in climate are associated with increased erosion and silicate weathering that consumes atmospheric CO2. However, it has been hypothesized recently that an increase in global continental erosion in the last 10 million years did not take place at all. Rather, the observed worldwide increase in sedimentation rates is suspected to be a measurement artifact introduced by the different time scales over which sedimentation was measured, and the incomplete preservation of the sediment record.Here, it will be tested whether erosion rates have increased over the late Neogene by analyzing preserved sedimentary records and modern river sediment for their cosmogenic nuclide concentrations. Quartz in buried river sediment carries a memory of the rivers´ basin‐wide denudation rate, in the form of in situ‐produced cosmogenic nuclides (10Be, 26Al). Thus denudation rates, being the sum of erosion and weathering, can be reconstructed throughout the past several million years. Samples from sedimentary records and modern sediment from the largest river basins on all continents (e.g. the Amazon, Mississippi, Ganges, Congo, Murray‐Darling, Danube), covering > 33×106 km2 of Earth´s surface, will be measured for their cosmogenic nuclide concentrations, thereby obtaining a statistically significant coverage of global erosion in several time slices. Analyzing this record at coarse time resolution will provide average, long‐term sediment production rates that will allow to decipher the feedbacks between weathering, erosion and atmospheric CO2 levels.

晚新生代全球变冷已被认为与全球沉积速率的增加有关，这被解释为由于山地侵蚀速率的增加。增强的造山活动和气候变化都与侵蚀和硅酸盐风化的增加有关，而侵蚀和硅酸盐风化会消耗大气中的二氧化碳。然而，最近有一种假设认为，在过去的1000万年里，全球大陆侵蚀的增加根本没有发生。相反，观测到的世界范围内沉积速率的增加被怀疑是由于测量沉积的不同时间尺度和沉积记录保存不完整而引起的测量误差。在这里，通过分析保存下来的沉积记录和现代河流沉积物的宇宙核素浓度，将测试在新近纪晚期侵蚀速率是否增加。埋藏的河流沉积物中的石英以原位产生的宇宙核素的形式携带着河流流域范围内剥蚀速率的记忆（10Be, 26Al）。因此，剥蚀率，即侵蚀和风化的总和，可以重建过去几百万年的剥蚀率。来自各大洲最大河流流域（如亚马逊河、密西西比河、恒河、刚果河、墨累—达令河、多瑙河）的沉积记录和现代沉积物样本，覆盖了地球表面100 33×106平方公里，将测量它们的宇宙成因核素浓度，从而在几个时间片中获得具有统计意义的全球侵蚀覆盖范围。以粗时间分辨率分析这一记录将提供平均的、长期的沉积物生成速率，从而破译风化、侵蚀和大气二氧化碳水平之间的反馈。