Secular cooling and crystallization of partially molten Archaean continental crust over 1 Ga

IF 2 4区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY
Olivier Vanderhaeghe , Célia Guergouz , Cécile Fabre , Stéphanie Duchêne , David Baratoux
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引用次数: 15

Abstract

The protracted tectonic and magmatic record of cratons over the Archaean Eon has been classically interpreted in terms of long-lived shallow-dipping subduction or repeated mantle plumes. In this paper, we use the 1D conductive heat equation to model the evolution of the geotherm of a generic felsic-dominated Archaean cratonic nuclei solely considering the secular decay of radioactive isotopes (238U, 235U, 232Th, and 40K), responsible for heat production in the crust. Using a range of plausible parameters for crustal thickness, lithospheric thickness, and surface heat flux, this modelling shows that Archaean crust was characterized by an initially high geothermal gradient at 3.5 Ga, with a Moho temperature close to 900 °C, and that it might have remained partially molten for about one billion years. The existence of a partially molten crust for an extended period of time offers an alternative option to shallow-dipping subduction or repeated mantle plumes for the understanding of the peculiar tectonic evolution of Archaean cratons marked by (i) protracted high-temperature metamorphism and magmatism associated with crustal differentiation, and (ii) widespread deformation characterized by structural domes attributed to the development of crustal-scale gravitational instabilities.

1ga以上部分熔融的太古代大陆地壳的长期冷却和结晶
太古宙克拉通漫长的构造和岩浆记录被经典地解释为长期的浅倾俯冲或重复的地幔柱。在本文中,我们使用一维导热方程来模拟一个以硅质为主的太古宙克拉通核的地热演化,并考虑了地壳中负责产热的放射性同位素(238U、235U、232Th和40K)的长期衰变。利用地壳厚度、岩石圈厚度和地表热通量等一系列合理的参数,该模型表明,太古代地壳在3.5 Ga时具有较高的地温梯度,莫霍温度接近900℃,并且可能在大约10亿年的时间里保持部分熔融状态。部分熔融地壳的长期存在,为理解太古宙克拉通的特殊构造演化提供了一种替代浅倾俯冲或重复地幔柱的选择,其特征是(i)与地壳分异有关的持久高温变质和岩浆作用,以及(ii)由于地壳尺度重力不稳定性的发展而以结构穹隆为特征的广泛变形。
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来源期刊
Comptes Rendus Geoscience
Comptes Rendus Geoscience 地学-地球科学综合
CiteScore
2.80
自引率
14.30%
发文量
68
审稿时长
5.9 weeks
期刊介绍: Created in 1835 by physicist François Arago, then Permanent Secretary, the journal Comptes Rendus de l''Académie des sciences allows researchers to quickly make their work known to the international scientific community. It is divided into seven titles covering the range of scientific research fields: Mathematics, Mechanics, Chemistry, Biology, Geoscience, Physics and Palevol. Each series is led by an editor-in-chief assisted by an editorial committee. Submitted articles are reviewed by two scientists with recognized competence in the field concerned. They can be notes, announcing significant new results, as well as review articles, allowing for a fine-tuning, or even proceedings of symposia and other thematic issues, under the direction of invited editors, French or foreign.
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