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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The internal structure of fault zones in basaltic sequences
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The internal structure of fault zones in basaltic sequences

机译：玄武岩层序断裂带的内部构造

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摘要

Normal faults in basalt along mid-ocean ridges and continental rifts play a major role in the formation of topography, advection of fluids, and the dynamics of biosphere. However, almost nothing is known of the internal structure of volcanic growth faults at depth, where many key processes take place. In this paper we present the results of scaled model experiments validated against outcrop studies of a volcanic growth fault system on Hawai'i. The analogue model uses cohesive hemihydrate powder, with carefully characterized physical properties. A cohesion of 62 Pa, friction angle of 0.71 and tensile strength of 33 Pa imply a length scaling ratio of 1:5000-50,000 between the model and the upper part of extending oceanic crust with a basalt column above a normal fault. Time lapse imagery, high resolution particle image velocimetry and field observations show ground flexure in an initial elastic stage before subvertical mode I fissures propagate from the surface downwards. Some of the mode I fractures become inactive, while others develop into massively dilatant normal faults. The dominant processes within the faults are brecciation, block rotation and gravitational transport of fragments along the fault, maintaining meter-sized cavities to a depth of several hundred meters. Even when these volcanic growth faults, are resurfaced, a pervasive dilatancy persist within the system. If circulating seawater provides a sufficient oxygen supply, the large cavities in normal faults at mid-ocean ridges could harbour large ocean floor life forms to several hundred meters depth. (c) 2006 Elsevier B.V. All rights reserved.
机译：沿中海脊和大陆裂谷的玄武岩的正常断层在地形的形成，流体的对流以及生物圈的动力学中起着重要作用。但是，对于发生许多关键过程的深部火山生长断层的内部结构，几乎一无所知。在本文中，我们介绍了针对夏威夷火山生长断层系统的露头研究进行验证的比例模型实验的结果。模拟模型使用具有粘性的半水合物粉末，具有精心表征的物理特性。内聚力为62 Pa，摩擦角为0.71，抗拉强度为33 Pa，意味着模型与正断层上方玄武岩柱延伸的大洋地壳上部之间的比例比例为1：5000-50,000。延时图像，高分辨率粒子图像测速仪和野外观察显示，在亚垂直模式I裂缝从表面向下传播之前的初始弹性阶段，地面弯曲。我的某些模式骨折变得不活跃，而另一些则发展成大量扩张的正常断层。断层内部的主要过程是沿断层的断裂，块旋转和碎屑的重力输送，将几米大小的空洞保持到几百米的深度。即使这些火山生长断层再次出现，系统中仍然存在普遍的扩张性。如果循环海水提供足够的氧气供应，那么在大洋中脊正断层中的大孔洞可能蕴藏着数百米深的大型海床生命形式。 （c）2006 Elsevier B.V.保留所有权利。

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