新生代有机碳循环失衡的氧化还原约束

IF 1.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY
M. Galvez
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引用次数: 3

摘要

在地质时间尺度上,大气O2的变化通常归因于陆地上有机碳(OC)和还原性硫的风化作用(大气O2的主要汇项)与海洋沉积物中有机碳和还原性硫的埋藏(大气中O2的主要来源项)之间的不平衡。但铁周期也很重要。利用地球外逸层、大陆和地幔储层之间的C、Fe、S和H通量的汇编,我证明了海洋岩石圈的热液风化和SO2的火山脱气是O2的净汇,在新生代期间约为2.7±1.1 Tmol O2/y。在同一时间间隔内,大气氧浓度接近恒定,这表明这种火成岩汇被碳、硫和铁的沉积旋回所补偿。在过去50-60 Myr期间,OC的净俯冲和净增加可能是主要的贡献,因此是大气O2的净来源。这一结果表明,新生代的氧化还原稳定状态是由太阳(光合)能量的净输入(~ 0.8 ~ 2 EJ/y)动态地维持在岩石圈的C、S和Fe循环中。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Redox constraints on a Cenozoic imbalance in the organic carbon cycle
Over geological timescales, variations in atmospheric O2 are typically attributed to the imbalance between the weathering of organic carbon (OC) and reduced sulfur on land, the major sink terms for atmospheric O2, and the burial of OC and reduced sulfur in marine sediments, the major source terms of O2 to the atmosphere. But the Fe cycle matters too. Using a compilation of C, Fe, S and H fluxes between the Earth's exosphere, continents, and mantle reservoirs, I demonstrate that hydrothermal weathering of the oceanic lithosphere and volcanic degassing of SO2 have acted as net sinks of O2, amounting to ca. 2.7 ± 1.1 Tmol O2/y, over the Cenozoic. Near constancy of atmospheric oxygen concentrations over the same interval of time suggests that this igneous sink is compensated by the sedimentary cycles of C, S and Fe. The net subduction and accretion of OC likely made the dominant contribution and, therefore, operated as a net source of atmospheric O2 over the last 50-60 Myr. This result implies that redox steady-state in the Cenozoic is dynamically maintained by a net input of solar (photosynthetic) energy, ∼ 0.8 to 2 EJ/y, into the lithospheric cycles of C, S and Fe.
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来源期刊
American Journal of Science
American Journal of Science 地学-地球科学综合
CiteScore
5.80
自引率
3.40%
发文量
17
审稿时长
>12 weeks
期刊介绍: The American Journal of Science (AJS), founded in 1818 by Benjamin Silliman, is the oldest scientific journal in the United States that has been published continuously. The Journal is devoted to geology and related sciences and publishes articles from around the world presenting results of major research from all earth sciences. Readers are primarily earth scientists in academia and government institutions.
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