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

0409162昆斯这是一项多学科的研究，以解决地球上最高的沿海山脉-阿拉斯加南部和加拿大西北部的圣埃利亚斯山脉的演变。 这个造山带是在过去几百万年里，随着雅库塔特块体（一个大陆-海洋板块）试图俯冲到阿留申岛弧-海沟系统的东端之下而发展起来的。 圣伊莱亚斯山脉长约500公里，宽约150公里，是地壳汇聚引起的快速抬升与快速移动的大型温带冰川区域系统引起的快速折返之间动态平衡的产物。 大多数沉积物要么沉积在宽阔的大陆架上，要么沉积在深海扇中，并提供了伴随造山运动的构造、气候、侵蚀和海平面变化事件的完整记录。 该项目的总体目标是为圣埃利亚斯造山带开发一个综合模型，该模型考虑了区域板块构造过程、结构发展和快速侵蚀的相互作用。 研究的重点是系统内的变形从上地幔流动到近地表断裂和折返的划分。 这项研究将调查斜碰撞的地球动力学的条件下，将允许PI解决几个重要的和基本的问题：-强烈的第四纪冰川侵蚀重新分布质量在造山带足以改变区域变形模式，并已集中侵蚀沿着深冰川山谷足以本地化地壳应变？变形是如何划分为岩石圈缩短和隆起与拆离地壳的侧向挤压，强烈的侵蚀是否影响这种划分？造山运动主要是由浮力海洋高原俯冲还是由附着在异地洋壳上的小微大陆块碰撞驱动的？解决这些问题具有广泛的意义，了解斜碰撞的地球动力学一般，不同的机制在发展中的作用远场造山效应，和控制侵蚀的发展过程中的滑动分割斜收敛。 该项目还对小型大陆板块相对于海洋高原的俯冲/增生如何促成大陆变形，以及这些碎片最终在构造地壳拼贴中的命运产生了一般性影响，这几乎是所有大陆的典型特征。 具体来说，P.I.s提出了一个多学科的方法，涉及地震学家（地下成像和地震活动性），地质学家，大地测量学家，冰川学家，地质年代学家和地球动力学建模。

0409162KoonsThis 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 development of far-field orogenic effects, and the control of erosion on development of slip partitioning during oblique convergence. The project also has general implications for how subduction/accretion of small continental terranes versus oceanic plateaus contribute to deformation of the continents, and ultimately the fate of these fragments in construction of the crustal collage which is typical of virtually all continents. Specifically, the P.I.s propose a multidisciplinary approach involving seismologists (subsurface imaging and seismicity), geologists, geodesists, glaciologists, geochronologists, and geodynamic modelers.