A relatively reduced Hadean continental crust and implications for the early atmosphere and crustal rheology
A relatively reduced Hadean continental crust and implications for the early atmosphere and crustal rheology
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相对缩小的冥古宙大陆地壳及其对早期大气和地壳流变学的影响
DOI：
10.1016/j.epsl.2014.02.056
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发表时间：
2014-05
影响因子：
5.3
通讯作者：
Scaillet Bruno
中科院分区：
文献类型：
--
作者：
Yang Xiaozhi;Gaillard Fabrice;Scaillet Bruno
人们普遍认为，地球在其早期吸积过程中经历了强烈的还原，然而，对距今40亿年前的地球物质进行的地球化学调查从未捕捉到从地球早期盛行的还原态到现代氧化地壳和地幔的转变。通过结合地壳成因火成锆石的现有微量元素数据，我们表明，冥古宙大陆地壳比现代大陆地壳明显减少，并且直到约 36 亿年前才经历了渐进氧化。我们认为，冥古宙大陆地壳氧化态的增加与晚饰层期间球粒陨石添加强度的逐渐下降有关。在冥古宙花岗岩地壳形成过程中，富含碳和氢的球粒陨石物质的输入肯定有利于岩浆活动的强烈减少。冥古宙期间冷、湿和减少的花岗岩岩浆作用的结合意味着除了由热还原玄武岩熔体脱气产生的富含CO和H2的火山物质之外，还产生了富含甲烷的流体，这些熔体在晚期饰面期间被输送的材料改性。当晚饰面事件结束时，地幔正常减压熔融产生的岩浆为喷发的熔岩和相关地壳提供了更多的氧化条件，释放出富含二氧化碳和水的气体。我们的模型表明，冥古宙大陆地壳可能比现在脆弱得多，有利于底板岩浆的侵入，从而使早期地球的地壳生长更快。
It is widely believed that the Earth was strongly reduced during its early accretion, however, the transition from the reduced state that prevailed during Earth's early period to the modern oxidized crust and mantle has never been captured by geochemical surveys on Earth materials as old as ∼4.0 billion years ago. By combining available trace-elements data of igneous zircons of crustal origin, we show that the Hadean continental crust was significantly more reduced than its modern counterpart and experienced progressive oxidation till ∼3.6 billions years ago. We suggest that the increase in the oxidation state of the Hadean continental crust is related to the progressive decline in the intensity of chondritic addition during the late veneer. Inputs of carbon- and hydrogen-rich chondritic materials during the formation of Hadean granitic crust must have favored strongly reduced magmatism. The conjunction of cold, wet and reduced granitic magmatism during the Hadean implies the production of methane-rich fluids, in addition to the CO- and H2-rich volcanic species produced by degassing of hot reduced basaltic melts as modified by delivered materials during the late veneer. When the late veneer events ended, magma produced by normal decompression melting of the mantle imparted more oxidizing conditions to erupted lavas and the related crust, emitting CO2- and H2O-rich gases. Our model suggests that the Hadean continental crust was possibly much weaker than present-day, facilitating intrusion of underplating magma and thus allowing faster crustal growth in the early Earth.
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影响因子：
64.8
作者：
A. Holzheid;P. Sylvester;H. O’Neill;D. Rubie;H. Palme
通讯作者：
A. Holzheid;P. Sylvester;H. O’Neill;D. Rubie;H. Palme
影响因子：
6.2
作者：
Michael E. Chang
通讯作者：
Michael E. Chang
DOI：
10.1073/pnas.1019191108
发表时间：
2011-04-05
影响因子：
11.1
作者：
Parker, Eric T.;Cleaves, Henderson J.;Bada, Jeffrey L.
通讯作者：
Bada, Jeffrey L.
DOI：
10.1016/j.cageo.2005.03.003
发表时间：
2005-07
期刊：
Comput. Geosci.
影响因子：
--
作者：
J. Huizenga
通讯作者：
J. Huizenga
影响因子：
--
作者：
W. Tonks;H. Melosh
通讯作者：
W. Tonks;H. Melosh