Multiple oscillations in Neoarchaean atmospheric chemistry
Multiple oscillations in Neoarchaean atmospheric chemistry
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DOI：
10.1016/j.epsl.2015.09.018
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发表时间：
2015-12-01
影响因子：
5.3
通讯作者：
Claire, Mark W.
中科院分区：
文献类型：
--
作者：
Izon, Gareth;Zerkle, Aubrey L.;Claire, Mark W.
大氧化事件（GOE）代表了地球历史上的一个关键时刻，标志着大气中的氧气从百万分之几上升到24.5 - 23.2亿年前（Ga）的百分比水平。虽然行星氧合无疑导致了当代地球系统的诞生，但控制这种化学重组的触发器和机制仍然难以捉摸。在GOE的前奏大气的成分的定量估计是理解这一氧化事件的核心。先前对来自南非Griqualand盆地的2.65-2.5 Ga沉积物的分析引发了一幅不寻常的地球环境的诱人图片，暗示大气层周期性地由甲烷光解形成的有机颗粒层（“霾”）主导。然而，这一假设尚未得到验证。在这里，我们提出了四个新的耦合碳和四重硫同位素记录远，时间相当于（2.7-2.5 Ga），从南非和西澳大利亚州的沉积序列。这些扩展记录揭示了类似的化学地层学趋势，支持动态终端新太古代大气，在甲烷浓度升高的朦胧状态和无雾缺氧背景状态之间振荡。我们认为，这些大气畸变与气候或风化诱导的反馈增强营养物质输送所导致的生物甲烷通量增加有关。这些数据质疑一个简单的，单向的行星氧合的规范观点，并表示GOE的序曲是由地球生物圈系统内的复杂反馈控制的。(C)2015作者由爱思唯尔公司出版。这是一篇开放获取的文章，使用CC BY许可证（http：//creativecommons.org/licenses/by/4.0/）。
The Great Oxidation Event (GOE) represents a crucial juncture in Earth history, signifying the rise in atmospheric oxygen from parts per million to percent levels at similar to 2.45-2.32 billion-years-ago (Ga). Although planetary oxygenation undoubtedly led to the inception of the contemporary Earth system, the trigger(s) and mechanism(s) controlling this chemical reorganisation remain elusive. Quantitative estimates of the atmosphere's composition in the prelude to the GOE are central to understanding this oxygenation event. Previous analyses of 2.65-2.5 Ga sediments from the Griqualand Basin (South Africa) invoke a tantalising picture of an unusual Earth environment, alluding to an atmosphere periodically dominated by a layer of organic particles ("haze") formed from methane photolysis. However, as yet this hypothesis has remained untested. Here we present four new coupled carbon and quadruple sulphur isotope records from distal, time equivalent (2.7-2.5 Ga), sedimentary successions from South Africa and Western Australia. These extended records reveal similar chemostratigraphic trends, supporting a dynamic terminal-Neoarchaean atmosphere, oscillating between a hazy state at elevated methane concentrations, and a haze-free anoxic background state. We suggest these atmospheric aberrations were related to heightened biogenic methane fluxes fuelled by enhanced nutrient delivery from climatically or weathering induced feedbacks. These data question the canonical view of a simple, unidirectional planetary oxygenation and signify that the overture to the GOE was governed by complex feedbacks within the Earth-biosphere system. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).