Convergence accommodation and kinematics in orogenic systems

在过去的15年里，我们对山脉带如何演化的认识取得了重大进展。这一进展很大程度上来自喜马拉雅地区开展的工作，那里的研究人员为暴露在那里的出土的中地壳岩石的演化开发了热力学模型。在验证这些模型所作的地质预测时，通过构建穿过出土的中地壳的详细的压力-温度-时间(变形)路径，发现了一系列隐秘的断层结构，并已在沿山链长度的不同位置被发现。这种构造的出现表明了喜马拉雅中地壳折返的历史更加复杂，其内部水平缩短和垂直增厚的程度明显高于以前认识的水平缩短和垂直增厚。由于这些断裂构造只是最近的发现，关于它们的地质特征和它们在喜马拉雅运动演化中的整体作用的数据很少。此外，这些构造的存在使以前的山脉带内部组装模型受到了质疑，这些模型主要基于喜马拉雅山脉的数据。这项拟议的研究旨在了解碰撞事件中活跃的过程，以及这些新认识的结构可能发挥的作用。为了实现这一目标，将对三个目标地区的神秘断裂结构进行全面、综合的地质调查，包括详细的野外工作和实验室分析，这些地区跨越一系列地质时代(新生代至太古宙)和造山类型(大陆-大陆至增生)。喜马拉雅、加拿大科迪勒拉和萨斯喀彻温省北部的研究区域将提供比较中下地壳内隐蔽结构在不同地质时期的演化的手段，并为新的全球相关框架提供基础，从而为我们目前的造山模式提供信息。

The past 15 years have seen major advances in our knowledge of how mountain belts evolve. Much of this progress has come from work carried out in the Himalaya where researchers have developed thermo-mechanical models for the evolution of the exhumed midcrustal rocks exposed therein. While testing geologic predictions made by these models, through the construction of detailed pressure-temperature-time(-deformation) paths across the exhumed mid-crust, a series of cryptic fault structures were discovered and have now been identified in various locations along the length of the mountain chain. The occurrence of such structures indicates a more complex history for the exhumed Himalayan mid-crust with significantly more internal horizontal shortening and vertical thickening than previously recognized. Because these fault structures are only recent discoveries, little data exist on their geologic characteristics and their overall role in the kinematic evolution of the Himalaya. Moreover, the existence of these structures calls into question previous models for the assembly of the interior of mountain belts, which have been largely based on data from the Himalaya. The proposed research aims to understand the processes active during collisional events and the role that these newly recognised structures may have played. To meet this goal, comprehensive, integrative geologic investigations, including detailed field work and laboratory analysis, will be carried out across enigmatic fault structures in three targeted areas that span a range of geologic time (Cenozoic to Archean) and orogenic types (continent-continent to accretionary). Study areas in the Himalaya, the Canadian Cordillera, and northern Saskatchewan will provide the means to compare the evolution of cryptic structures within the mid-to-lower crust across geologic time and provide the basis for a new globally relevant framework to inform our present mountain building paradigm.