Lithosphere differentiation in the early Earth controls Archean tectonics
Lithosphere differentiation in the early Earth controls Archean tectonics
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DOI：
10.1016/j.epsl.2019.115755
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发表时间：
2019-11-01
影响因子：
5.3
通讯作者：
Clos, F.
中科院分区：
文献类型：
--
作者：
Capitanio, F. A.;Nebel, O.;Clos, F.
在早期地球上运作的过程和形成它的构造体制受到很差的约束，反映了高度破碎的岩石记录和地球动力学条件的不确定性。早期地球动力学的大多数模型援引一个不良的移动的盖制度，涉及很少或偶发运动的岩石圈，上面的对流地幔。然而，这样的体制与太古代构造的记录并不一致，太古代构造显示出与非板块构造或板块构造相关的对比环境。在这里，我们提出了早期地球的一个机制，其中发散处的渐进熔融提取导致形成了大部分较硬的岩石圈盖，称为原板块。这些原型板块使应力传播集中在其边缘，这是当时的轨迹延伸，而不是缩短，逆冲推覆和增厚，形成相邻的原型板块。我们测试这一假设嵌入岩石圈硬化熔体提取过程中地幔对流的热力学模型，在太古代盛行的条件下。我们证明了迁移的出现，刚性的原型板，其中长期集中压缩的区域与停滞盖的残余共存，从而再现了广泛的二分法提出的太古代构造记录。这些不同的构造模式共存于一个单一的制度，是可行的，因为Hadean和持续，直到过渡到现代板块构造。(C)2019爱思唯尔B.V.保留所有权利。
The processes that operated on the early Earth and the tectonic regimes in which it was shaped are poorly constrained, reflecting the highly fragmentary rock record and uncertainty in geodynamic conditions. Most models of early Earth geodynamics invoke a poorly mobile lid regime, involving little or episodic movement of the lithosphere, above a convecting mantle. However, such a regime does not reconcile with the record of Archean tectonics, which displays contrasting environments associated with either non-plate tectonics or plate tectonics. Here, we propose a regime for the early Earth in which progressive melt extraction at sites of divergence led to the formation of large portions of stiffer lithospheric lid, called proto-plates. These proto-plates enabled stress propagation to be focussed at their margins, which were then the locus for extension as oppose to shortening, under-thrusting and thickening to form adjoining proto-cratons. We test this hypothesis embedding lithospheric stiffening during melt extraction in thermo-mechanical models of mantle convection, under conditions that prevailed in the Archean. We demonstrate the emergence of migrating, rigid proto-plates in which regions of prolonged focused compression coexist with remnants of the stagnant lid, thereby reproducing the widespread dichotomy proposed for the Archean tectonic record. These diverse tectonic modes coexist in a single regime that is viable since the Hadean and lasted until the transition to modern plate tectonics. (C) 2019 Elsevier B.V. All rights reserved.