当前位置: X-MOL 学术Earth Planet. Sci. Lett. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Stirred not shaken; critical evaluation of a proposed Archean meteorite impact in West Greenland
Earth and Planetary Science Letters ( IF 4.8 ) Pub Date : 2021-01-11 , DOI: 10.1016/j.epsl.2020.116730
Chris Yakymchuk , Christopher L. Kirkland , Aaron J. Cavosie , Kristoffer Szilas , Julie Hollis , Nicholas J. Gardiner , Pedro Waterton , Agnete Steenfelt , Laure Martin

Large meteorite impacts have a profound effect on the Earth's geosphere, atmosphere, hydrosphere and biosphere. It is widely accepted that the early Earth was subject to intense bombardment from 4.5 to 3.8 Ga, yet evidence for subsequent bolide impacts during the Archean Eon (4.0 to 2.5 Ga) is sparse. However, understanding the timing and magnitude of these early events is important, as they may have triggered significant change points to global geochemical cycles. The Maniitsoq region of southern West Greenland has been proposed to record a ∼3.0 Ga meteorite impact, which, if confirmed, would be the oldest and only known impact structure to have survived from the Archean. Such an ancient structure would provide the first insight into the style, setting, and possible environmental effects of impact bombardment continuing into the late Archean. Here, using field mapping, geochronology, isotope geochemistry, and electron backscatter diffraction mapping of 5,587 zircon grains from the Maniitsoq region (rock and fluvial sediment samples), we test the hypothesis that the Maniitsoq structure represents Earth's earliest known impact structure. Our comprehensive survey shows that previously proposed impact-related geological features, ranging from microscopic structures at the mineral scale to macroscopic structures at the terrane scale, as well as the age and geochemistry of the rocks in the Maniitsoq region, can be explained through endogenic (non-impact) processes. Despite the higher impact flux, intact craters from the Archean Eon remain elusive on Earth.



中文翻译:

搅拌不动;格陵兰西部格陵兰陨石撞击的拟议评估

大型陨石撞击对地球的地圈,大气层,水圈和生物圈产生深远的影响。人们普遍认为,早期地球在4.5至3.8 Ga范围内受到强烈轰炸,但是在太古代Eon(4.0至2.5 Ga)期间随后发生的硼化物撞击的证据很少。但是,了解这些早期事件的时间和强度很重要,因为它们可能触发了全球地球化学循环的重大变化点。已提议在西格陵兰南部的Maniitsoq地区记录约3.0 Ga的陨石撞击,如果确认,它将是从太古宙遗留下来的最古老且唯一已知的撞击构造。这种古老的结构将提供对冲击轰击持续到太古宙时代的风格,环境和可能的环境影响的初步了解。在这里,我们使用Maniitsoq地区(岩石和河流沉积物样品)的5587个锆石的场图,年代学,同位素地球化学和电子背散射衍射图,验证了Maniitsoq结构代表地球最早已知撞击结构的假设。我们的综合调查表明,先前提出的与冲击有关的地质特征,从矿物尺度的微观结构到地层尺度的宏观结构,以及Maniitsoq地区岩石的年龄和地球化学,都可以通过内生解释(非影响)流程。尽管较高的冲击通量,但太古宙的完整陨石坑在地球上仍然难以捉摸。来自Maniitsoq地区的587个锆石晶粒(岩石和河流沉积物样本),我们检验了Maniitsoq结构代表地球最早已知撞击结构的假设。我们的综合调查表明,先前提出的与冲击有关的地质特征,从矿物尺度的微观结构到地层尺度的宏观结构,以及Maniitsoq地区岩石的年龄和地球化学,都可以通过内生解释(非影响)流程。尽管较高的冲击通量,但太古宙的完整陨石坑在地球上仍然难以捉摸。来自Maniitsoq地区的587个锆石晶粒(岩石和河流沉积物样本),我们检验了Maniitsoq结构代表地球最早已知撞击结构的假设。我们的综合调查表明,先前提出的与冲击有关的地质特征,从矿物尺度的微观结构到地层尺度的宏观结构,以及Maniitsoq地区岩石的年龄和地球化学,都可以通过内生解释(非影响)流程。尽管较高的冲击通量,但太古宙的完整陨石坑在地球上仍然难以捉摸。我们的综合调查表明,先前提出的与冲击有关的地质特征,从矿物尺度的微观结构到地层尺度的宏观结构,以及Maniitsoq地区岩石的年龄和地球化学,都可以通过内生解释(非影响)流程。尽管较高的冲击通量,但太古宙的完整陨石坑在地球上仍然难以捉摸。我们的综合调查表明,先前提出的与冲击有关的地质特征,从矿物尺度的微观结构到地层尺度的宏观结构,以及Maniitsoq地区岩石的年龄和地球化学,都可以通过内生解释(非影响)流程。尽管较高的冲击通量,但太古宙的完整陨石坑在地球上仍然难以捉摸。

更新日期:2021-01-11
down
wechat
bug