Coupling between crustal superstructure, infrastructure and surface processes: test along the Himalayan orogenic front

The Earth's geosphere, atmosphere, hydrosphere and biosphere interact in diverse ways at a variety of spatial and temporal scales. Studying the impacts of climate and erosion on tectonics (the study of the Earth's crust and the forces that influence it) is one of the most active research topics in the geological sciences. The Himalaya is the archetypal mountain range formed by the collision of continents, and its southern rampart is an exceptional natural laboratory to test the interactions between Earth's interior and surface processes. For example, the Indian summer monsoon plays an essential role in erosion along the Himalaya and its intensity has varied considerably since it was established some 12 million years ago. Conversely, the movement of Himalayan tectonic plates has remained fairly steady since collision between India and Eurasia began ~55 million years ago. As the same rock types are found along the entire 2000 km-wide mountain range, observed changes in surface geology are most likely due to the variation of erosion in space and time. The formation of the Himalaya is currently explained by two contrasting tectonic models that differ in their predictions for the sequence of deformation along the main structures. The rationale of this investigation is to provide a comprehensive study of the ages of the main geological structures and erosion rates, as a field-based test of the model predictions. This will provide crucial information about the coupling of deformation between middle and upper crustal levels and ultimately about the links between deep crustal deformation and surface processes. Floods, landslides, debris flows and even earthquakes are consequences of the processes that create dynamic landscapes in tectonically-active areas. Comprehending the rate and variability of such mass transport systems on the Earth's surface and understanding the Earth's response to climate changes over geologic time will lead to better hazard forecasting. In addition to taking a leadership role in the discipline, Canada will benefit from further understanding of the underlying processes responsible for the Earth's major evolutionary steps that can inform into policy development initiatives regarding geohazard, environmental protection and climate change.