Collaborative Research: ST. Elias Erosion/tectonics Project (STEEP)

• Main Author: Koons, Peter O.
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2010
• Subjects: St. Elias Mountains; Alaska; Canada; Continental-oceanic terrane; Subduction; Orogen; Tectonics and Structure; Collaborative Research: St. Elias Erosion/Tectonics Project (STEEP); glacier*; glaciers; Yakutat
• Online Access: https://digitalcommons.library.umaine.edu/orsp_reports/253; https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1266&context=orsp_reports

This is a multi-disciplinary study to address the evolution of the highest coastal mountain range on Earth - the St. Elias Mountains of southern Alaska and northwestern Canada. This orogen has developed over the past few million years as the Yakutat block, a continental-oceanic terrane, has attempted subduction beneath the eastern end of the Aleutian arc-trench system. The ~500 km-long, 150 km-wide St. Elias mountain range is the product of the dynamic balance between rapid uplift induced by crustal convergence and rapid exhumation by a regional system of large, fast-moving temperate glaciers. Most sediments are deposited either on a broad shelf or in deepsea fans and provide a complete record of the tectonic, climatic, erosional, and eustatic events that have accompanied the orogeny. The overarching goal of the project is to develop a comprehensive model for the St. Elias orogen that accounts for the interaction of regional plate tectonic processes, structural development, and rapid erosion. The focus of the study is on the partitioning of deformation within the system from upper mantle flow to near-surface faulting and exhumation. The study will investigate the geodynamics of oblique collision under a set of conditions that will allow the PIs to address several important and fundamental questions:- Has intense Quaternary glacial erosion redistributed mass in the orogen sufficiently to change regional deformational patterns, and has focused erosion along deep glacial valleys been sufficient to localize crustal strains?- How is deformation partitioned into lithospheric shortening and uplift versus lateral extrusion of the detached crust, and does intense erosion influence this partitioning?- Is the orogeny driven primarily by subduction of a buoyant oceanic plateau or by collision of a small microcontinental block attached to allochthonous ocean crust?Addressing these questions has broad implications for understanding the geodynamics of oblique collision in general, the role of different mechanisms in ...