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大陆稳定受陆地风化作用驱动

 2024/6/11 14:54:52 《最新论文》 作者:科学网小柯机器人 我有话说(0人评论) 字体大小:+

美国宾夕法尼亚州立大学Reimink, Jesse R.研究小组近日取得一项新成果。经过不懈努力,他们的最新研究揭示了陆地的风化作用使大陆稳定下来。该项研究成果发表在2024年5月8日出版的《自然》上。

据悉,地球上富硅的大陆花岗岩在类地行星中是独一无二的,对评价行星的宜居性至关重要。克拉通代表了永存的大陆碎片,约占地球大陆地壳的50%左右,但克拉通稳定的机制仍然是个谜。30-25亿年前,在中太古代晚期和新太古代时期,形成了大片强分化的地壳。该地壳含有丰富的花岗岩类岩石,其中U、Th、K的含量较高;这些火成岩的形成代表了大陆地壳稳定的最后阶段。

研究表明,由海平面以上大陆块的出现引发的陆地风化作用,促进了壳内熔融和过铝花岗岩类岩浆的生成。这导致了新太古代大陆地壳成分结构的重组。陆上风化作用将产热元素集中到陆源沉积物中,这些陆源沉积物被纳入地壳深部,在那里它们驱动地壳融化和化学分层,这是稳定克拉通岩石圈所必需的。

陆地风化作用与地壳最终分化之间的因果关系链,意味着克拉通稳定是大陆形成的必然结果。在地球历史上,放射成因产热的平均速度是现在的两倍,而富含产热元素的沉积岩的产生解决了一个长期存在的问题,即为什么许多克拉通在新太古代时期保持稳定。

附:英文原文

Title: Subaerial weathering drove stabilization of continents

Author: Reimink, Jesse R., Smye, Andrew J.

Issue&Volume: 2024-05-08

Abstract: Earth’s silica-rich continental crust is unique among the terrestrial planets and is critical for planetary habitability. Cratons represent the most imperishable continental fragments and form about 50% of the continental crust of the Earth, yet the mechanisms responsible for craton stabilization remain enigmatic. Large tracts of strongly differentiated crust formed between 3 and 2.5billion years ago, during the late Mesoarchaean and Neoarchaean time periods. This crust contains abundant granitoid rocks with elevated concentrations of U, Th and K; the formation of these igneous rocks represents the final stage of stabilization of the continental crust. Here, we show that subaerial weathering, triggered by the emergence of continental landmasses above sea level, facilitated intracrustal melting and the generation of peraluminous granitoid magmas. This resulted in reorganization of the compositional architecture of continental crust in the Neoarchaean period. Subaerial weathering concentrated heat-producing elements into terrigenous sediments that were incorporated into the deep crust, where they drove crustal melting and the chemical stratification required to stabilize the cratonic lithosphere. The chain of causality between subaerial weathering and the final differentiation of Earth’s crust implies that craton stabilization was an inevitable consequence of continental emergence. Generation of sedimentary rocks enriched in heat-producing elements, at a time in the history of the Earth when the rate of radiogenic heat production was on average twice the present-day rate, resolves a long-standing question of why many cratons were stabilized in the Neoarchaean period.

DOI: 10.1038/s41586-024-07307-1

Source: https://www.nature.com/articles/s41586-024-07307-1

来源:科学网 小柯机器人

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