Continental crust formation on early Earth controlled by intrusive magmatism
Continental crust formation on early Earth controlled by intrusive magmatism
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DOI：
10.1038/nature22042
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发表时间：
2017-05
期刊：
影响因子：
64.8
通讯作者：
A. Rozel;G. Golabek;C. Jain;P. Tackley;T. Gerya
中科院分区：
文献类型：
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作者：
A. Rozel;G. Golabek;C. Jain;P. Tackley;T. Gerya
早期地球的全球地球动力学机制在板块构造开始之前就已经存在，至今仍存在争议。由于地质和地球化学资料表明太古宙地幔温度较高，年轻岩浆活动比现今地球更强烈，因此提出了两种不同的壳幔相互作用模式：以火山活动为主的类木卫一热导管构造体制和以侵入岩浆活动为主的“深成粘盖”构造体制，这被认为适用于金星的动力学。两种构造体制都能产生原生英云闪长岩-奥长花岗岩-花岗闪长岩（TTG）陆壳，但岩石圈地温、陆壳产出率以及TTG组分比例差异较大，这意味着热管假说和深成岩黏盖假说可以用自然数据进行检验。在这里，我们调查创建原始TTG一样的大陆地壳使用自洽的全球热化学对流与岩浆过程的数值模型。我们表明，火山活动为主的热管构造模型的结果在寒冷的地壳地热，是不能产生类似地球的原始大陆地壳。相比之下，侵入岩浆活动为主的深成粘盖构造制度的结果在较热的地壳地热，并能够复制所观察到的各种TTG岩石的比例。使用一个系统的参数研究，我们表明，典型的现代喷发效率不到40%，导致生产的三个主要的原始地壳成分的预期量以前报告的现场数据，（低，中，高压TTG）。因此，我们的研究表明，前板块构造太古宙地球在全球范围内运作的深圳湾软盖政权，而不是在一个木卫一样的热管政权。
The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature,and more intense juvenile magmatism than in the present-day Earth,, two crust–mantle interaction modes differing in melt eruption efficiency have been proposed: the Io-like heat-pipe tectonics regime dominated by volcanism,and the “Plutonic squishy lid” tectonics regime governed by intrusive magmatism, which is thought to apply to the dynamics of Venus,,. Both tectonics regimes are capable of producing primordial tonalite–trondhjemite–granodiorite (TTG) continental crust,but lithospheric geotherms and crust production rates as well as proportions of various TTG compositions differ greatly,, which implies that the heat-pipe and Plutonic squishy lid hypotheses can be tested using natural data. Here we investigate the creation of primordial TTG-like continental crust using self-consistent numerical models of global thermochemical convection associated with magmatic processes. We show that the volcanism-dominated heat-pipe tectonics model results in cold crustal geotherms and is not able to produce Earth-like primordial continental crust. In contrast, the Plutonic squishy lid tectonics regime dominated by intrusive magmatism results in hotter crustal geotherms and is capable of reproducing the observed proportions of various TTG rocks. Using a systematic parameter study, we show that the typical modern eruption efficiency of less than 40 per cent leads to the production of the expected amounts of the three main primordial crustal compositions previously reported from field data,(low-, medium- and high-pressure TTG). Our study thus suggests that the pre-plate-tectonics Archean Earth operated globally in the Plutonic squishy lid regime rather than in an Io-like heat-pipe regime.