地质学中的压力与深度关系讨论:颗粒尺度压力差到岩石圈构造超压研究新进展

发布时间：2018-06-16 01:24

本文选题：压力差 + 构造超压　；参考：《地学前缘》2017年02期

【摘要】：地质学中普遍采用的压力与深度转化方法是基于阿基米德定律,该定律适用于重力场中的静流体压力条件下的压力与深度关系。然而,由于岩石圈的高黏度与各向异性特性和构造差应力作用,决定了岩石圈内的压力分布和应力分布受多种因素影响。基于近期新发表的研究成果,介绍了从颗粒尺度压力差到岩石圈构造超压研究新进展,讨论了地质学中的压力与深度关系问题。近期研究表明,与静压状态下获得的压力分布与深度关系相比,在差应力条件下获得的变质反应压力和相变压力要复杂得多。在差应力条件下,从微观尺度的变质反应和岩石颗粒间尺度到不同地质体之间、地壳内部构造带和岩石圈尺度都存在局部压力非均匀分布(构造超压)。在强烈隆升的高原地区,在高程差的重力势作用下也可以出现构造超压。这种压力非均匀的存在决定了变质反应压力和矿物相变压力不等同于静岩压力。热-力学耦合数值模拟结果显示,由于偏应力作用,在大陆碰撞造山带42km深度,构造超压达到2.2GPa,局部压力达到3.4GPa,远高于平均静岩压力。由此推测,在40~50km深度,就有可能出现高压-超高压变质作用。因此,根据变质反应和矿物相变确定的压力不能直接换算成岩石圈深度。
[Abstract]:The commonly used pressure and depth transformation method in geology is based on Archimedes' law, which is applicable to the relationship between pressure and depth under hydrostatic pressure in gravity field. However, the pressure distribution and stress distribution in the lithosphere are influenced by many factors due to the high viscosity, anisotropy and tectonic differential stress of the lithosphere. Based on the recently published research results, this paper introduces the new progress in the study of the pressure difference between granular scale and lithospheric tectonics, and discusses the relationship between pressure and depth in geology. Recent studies show that the pressure of metamorphic reaction and the pressure of phase transition under differential stress are much more complex than those obtained under static pressure and the relationship between the pressure distribution and the depth. Under the condition of differential stress, from the metamorphic reaction of microscale and the scale of intergranular rock to different geological bodies, there is a non-uniform distribution of local pressure (tectonic overpressure) in the crustal inner tectonic belt and lithospheric scale. Tectonic overpressure can also occur in strongly uplifted plateau areas under the action of gravity potential of elevation difference. The existence of this non-uniform pressure determines that the metamorphic reaction pressure and the mineral phase transition pressure are not equal to the static rock pressure. The results of thermal-mechanical coupling numerical simulation show that the tectonic overpressure is 2.2 GPA and the local pressure is 3.4 GPA at the depth of 42km in the continental collision orogenic belt, which is much higher than the average static rock pressure. Therefore, it is inferred that high pressure-ultra high pressure metamorphism may occur at the depth of 40~50km. Therefore, the pressure determined by metamorphic reaction and mineral transformation can not be directly converted into lithospheric depth.
【作者单位】：中国地震局地质研究所地震动力学国家重点实验室;
【基金】：国家自然科学基金项目(41374184) 地震动力学国家重点实验室自主课题(LED2013A05,LED2015A04)
【分类号】：P542.5

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