Convergence accommodation and kinematics in orogenic systems

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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.