• 主题
高级搜索  >
历史搜索 清空历史
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 >Convective destabilization of a thickened continental lithosphere
【24h】

Convective destabilization of a thickened continental lithosphere

机译：大陆岩石圈增厚的对流不稳定

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Removal or delamination of the lithospheric mantle in a late stage of mountain building is a process often invoked to explain syn orogenic extension, high temperature metamorphism, magmatism and uplift. One mechanism that could explain the lithospheric root detachment is the development of convective instabilities within the peridotitic lithosphere due to its high density. This mechanism is studied by two-dimensional convective numerical simulations in the simple case of a strongly temperature dependent viscous rheology appropriate for upper mantle rocks. We neglect here the weakening effect of a brittle rheology and of a crustal layer, and therefore we did not model tectonic deformations. Depending on the upper mantle viscosity and activation energy, a 300 km thick root can be inferred to be either indefinitely stable or to thicken with time or to thin with time. When the lithosphere is initially thicker than its equilibrium thickness, the convective flow at the base and on the sides of the lithospheric root is strong enough to cancel downwards heat conduction and to progressively remove the root. This flow is due to the finite density perturbations induced by the topography of the isotherms on the base and at the sides of the root. We derive two general parameterizations of the convective removal duration as a function of the equilibrium thickness, the thickening factor, the root width, and the rheological temperature scale. Using these relationships, and assuming that the lithospheric equilibrium thickness is about 100 km, the removal duration of a 250 km thick root ranges from 55 to 750 Myr depending on the root width. It is too small to explain the long term stability of cratonic lithospheric root, but too long to explain any sudden change in the stress and strain states in mountain belts development.
机译：在山区建筑的后期，岩石圈地幔的去除或分层是一个经常被用来解释同造山运动扩展，高温变质，岩浆作用和隆升的过程。解释岩石圈根部脱离的一种机制是由于其高密度，在橄榄岩圈岩石圈内对流不稳定性的发展。在二维热对流数值模拟的简单情况下，适用于上地幔岩石的强烈温度相关粘性流变学研究了这种机理。在这里我们忽略了脆性流变学和地壳层的削弱作用，因此我们没有对构造变形建模。根据上地幔的粘度和活化能，可以推断出300 km厚的根是无限稳定的，或者随着时间的推移变厚或随着时间变薄。当岩石圈最初的厚度大于其平衡厚度时，岩石圈根部底部和侧面的对流非常强，足以抵消向下的热传导并逐渐去除根部。这种流动是由于在根部和根部等温线的地形引起的有限密度扰动。我们得出了对流去除持续时间的两个一般参数，它们是平衡厚度，增稠系数，根部宽度和流变温度标度的函数。使用这些关系，并假设岩石圈平衡厚度约为100 km，则250 km厚的根的去除持续时间取决于根的宽度，范围为55至750 Myr。太小无法解释克拉通岩石圈的长期稳定性，而太长时间则无法解释山区开发中应力和应变状态的任何突然变化。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号