Convergence accommodation and kinematics in orogenic systems

在过去的15年里，我们对山带演变的认识取得了重大进展。这一进展很大程度上来自于在喜马拉雅地区开展的工作，在那里，研究人员开发出了地壳中部岩石的演化热力学模型。在测试这些模型所做的地质预测时，通过在挖掘出的中地壳中构建详细的压力-温度-时间（变形）路径，发现了一系列神秘的断层结构，现在已经在沿着山脉长度的不同位置确定了这些断层结构。这些构造的出现表明喜马拉雅中地壳的历史更为复杂，其内部水平缩短和垂直增厚的程度明显高于之前的认识。由于这些断层结构是最近才发现的，所以关于它们的地质特征及其在喜马拉雅运动演化中的总体作用的数据很少。此外，这些构造的存在对先前的山带内部构造模型提出了质疑，这些模型主要基于喜马拉雅的数据。提出的研究旨在了解碰撞事件中活跃的过程，以及这些新发现的结构可能发挥的作用。为了实现这一目标，将在三个目标区域进行全面、综合的地质调查，包括详细的野外工作和实验室分析，这些区域跨越了一系列地质时代（新生代到太古代）和造山带类型（大陆-大陆到增生）。喜马拉雅、加拿大科迪勒拉和萨斯喀彻温北部的研究区域将提供跨地质时期比较中下地壳隐构造演化的手段，并为新的全球相关框架提供基础，为我们目前的造山范例提供信息

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.**