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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 >Emplacement of shallow dikes and sills beneath a small basaltic volcanic center - The role of pre-existing structure (Paiute Ridge, southern Nevada, USA)
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Emplacement of shallow dikes and sills beneath a small basaltic volcanic center - The role of pre-existing structure (Paiute Ridge, southern Nevada, USA)

机译：在一个小的玄武岩火山中心下埋设浅堤和门槛-既有结构的作用（美国内华达州南部的派伊特里奇）

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摘要

Late Miocene sills and dikes in the Paiute Ridge area of southern Nevada were emplaced in an extensional setting beneath a small volume, alkali basaltic volcanic center. Dikes (400-5000 m long, 1.2-9 m wide) mostly occupy pre-existing E-dipping normal faults. Elastic deformation of the wall rocks alone cannot explain dike dimensions; inelastic deformation, wall rock erosion by flowing magma, and syn-emplacement extension of the host structural system also contributed to dike widths. After primarily subvertical emplacement, flow focused toward the southern end of one of the dikes to form a volcanic conduit. This dike and a fault-hosted radial dike subsequently were subject to high pressures due to transient volcanic processes. Three small sills (extending laterally up to similar to 500 m, and 20-46 m thick) and two larger sills (each having lateral dimensions similar to 1 km) locally branch off some dikes within similar to 250 m of the paleosurface. Individual small sills extend only into the hanging wall blocks of the faults that host their parent dikes, and are connected to the dikes by stems that are only a few tens of meters wide; elsewhere along their strikes the parent dikes extend above the sills. This mode of sill emplacement was caused by local rotation of principal stresses related to the intersection of the dike-hosting fault planes with the complex contact between relatively strong Paleozoic carbonates and weak Tertiary tuffs. Orientation of bedding planes in the tuffs controlled the direction of sill propagation. The three most areally extensive sills formed lopoliths with sagging roofs, indicating interaction with the free surface. (c) 2006 Elsevier B.V All rights reserved.
机译：内华达州南部Paiute Ridge地区的中新世晚期坎石和堤坝被放置在一个伸展的环境中，位于少量的碱性玄武岩火山中心之下。堤防（长400-5000 m，宽1.2-9 m）占据了先前存在的电子浸入正常断层。仅靠围岩的弹性变形不能解释堤的尺寸。非弹性变形，流动岩浆对围岩的侵蚀以及主体结构系统的同位扩展都对堤宽产生了影响。在主要是垂直下陷之后，流向堤坝之一的南端集中，形成火山管道。由于短暂的火山作用，该堤防和断层径向堤防随后遭受高压。三个小门槛（横向延伸至类似500 m，厚度为20-46 m）和两个大门槛（每个横向尺寸近似于1 km）在大约250 m的古地表内局部分流了一些堤防。单个小门槛仅延伸到承载其母堤的断层的悬挂墙块中，并通过仅几十米宽的茎与堤相连。沿他们罢工的其他地方，母堤坝延伸到门槛上方。这种基坑定位模式是由与堤坝主断层平面相交以及相对强的古生碳酸盐和弱的第三凝灰岩之间的复杂接触相交的主应力的局部旋转引起的。凝灰岩中的铺垫平面方向控制着窗台的传播方向。平面上最宽的三个门槛形成了带有下垂屋顶的石柱，表明与自由表面的相互作用。 （c）2006 Elsevier B.V保留所有权利。

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