∼100 km thick, is rigid. Segments of this spherical shell–lithospheric plates are drifting over a ductile asthenosphere. On the continents, the lithosphere includes the Earth's crust, ∼40 km thick, which is underlain by peridotitic rocks of the mantle. In most areas, at depths ∼20–40 km the continental crust is composed of basalts with density ∼2900kg m−3. At temperature and pressure typical for this depth, basalts are metastable and should transform into another assemblage of minerals which corresponds to garnet granulites and eclogites with higher densities 3300–3600 kg m−3. The rate of this transformation is extremely low in dry rocks, and the associated contraction of basalts evolves during the time ≥108 a. To restore the Archimede's equilibrium, the crust subsides with a formation of sedimentary basins, up to 10–15 km deep.Volumes of hot mantle with a water-containing fluid emerge sometimes from a deep mantle to the base of the lithosphere. Fluids infiltrate into the crust through the mantle part of the lithosphere. They catalyze the reaction in the lower crust which results in rock contraction with a formation of deep water basins at the surface during ∼106 a. The major hydrocarbon basins of the world were formed in this way. Infiltration of fluids strongly reduces the viscosity of the lithosphere, which is evidenced by narrow-wavelength deformations of this layer. At times of softening of the mantle part of the lithosphere, it becomes convectively replaced by a hotter and lighter asthenosphere. This process has resulted in the formation of many mountain ranges and high plateaus during the last several millions of years. Softening of the whole lithospheric layer which is rigid under normal conditions allows its strong compressive and tensile deformations. At the epochs of compression, a large portion of dense eclogites that were formed from basalts in the lower crust sink deeply into the mantle. In some cases they carry down lighter blocks of granites and sedimentary rocks of the upper crust which delaminate from eclogitic blocks and emerge back to the crust. Such blocks of upper crustal rocks include diamonds and other minerals which were formed at a depth of 100–150 km."> 加速地壳的非线性破坏 - raybet雷竞app,雷竞技官网下载,雷电竞下载苹果

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体积 6 |文章的ID 564943 | 10 页面 | https://doi.org/10.1155/S1026022601000322

加速地壳的非线性破坏

e . v . Artyushkov¹

¹地球物理联合研究所，B. Gruzinskaya 10，莫斯科123810，俄罗斯

收到了 2001年1月3日

摘要

地球的上部——岩石圈层， ∼ 厚100公里，坚硬。这些球形壳-岩石圈板块漂移在一个韧性软流圈上。在大陆上，岩石圈包括地壳， ∼ 40千米厚，下面是地幔的橄榄岩。在大多数地区，在深处 ∼ 20-40公里的陆壳由密度较大的玄武岩构成 ∼ 2900 公斤米 − 3. 。在这个深度典型的温度和压力下，玄武岩是亚稳的，应该转变成另一种矿物组合，对应于石榴石花岗岩和榴辉岩，密度更高，3300-3600公斤米 − 3. 。在干燥的岩石中，这种转化的速率非常低，同时玄武岩的收缩也在这段时间内不断演变 ≥ 10 8 a.为了恢复阿基米德平衡，地壳下沉形成沉积盆地，深可达10-15公里。大量的热地幔和含水的流体有时从深地幔涌向岩石圈的底部。流体通过岩石圈的地幔部分渗入地壳。它们催化下地壳的反应，导致岩石收缩并在地表形成深水盆地 ∼ 10 6 世界上主要的油气盆地都是这样形成的。流体的渗入大大降低了岩石圈的粘度，这一点可以从岩石圈的窄波长变形中得到证明。在岩石圈的地幔部分发生软化时，它就会被更热、更轻的软流圈所取代。在过去的几百万年里，这一过程导致了许多山脉和高原的形成。正常情况下岩石圈是刚性的，整个岩石圈的软化使其产生强烈的压缩和拉伸变形。在挤压时期，下地壳玄武岩形成的密集榴辉岩大量深陷到地幔中。在某些情况下，它们把较轻的花岗岩和上地壳的沉积岩带下来，这些岩石从羽化岩块中脱层，然后出现在地壳中。这些上层地壳岩石包括钻石和其他矿物，它们形成于100-150公里的深度。

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