HR: 1340h
AN: T23D-1664    [Abstracts]
TI: 3D Thermal/Mechanical Evolution Of The Plate Boundary Corner In SE Alaska
AU: * Barker, A
EM: adbarker@u.washington.edu
AF: University of Maine, University of Maine-Orono Department of Earth Sciences Bryand Global Sciences Center, Orono, ME 04469,
AU: Koons, P
EM: peter.koons@maine.edu
AF: University of Maine, University of Maine-Orono Department of Earth Sciences Bryand Global Sciences Center, Orono, ME 04469,
AU: Upton, P
EM: phaedra.upton@stonebow.otago.ac.nz
AF: University of Maine, University of Maine-Orono Department of Earth Sciences Bryand Global Sciences Center, Orono, ME 04469,
AU: Pavlis, T
EM: pavlis@geo.utep.edu
AF: University of Texas-El Paso, University of Texas at El Paso Geological Sciences, El Paso, TX 79968,
AU: Chapman, J
EM: jbchapman@utep.edu
AF: University of Texas-El Paso, University of Texas at El Paso Geological Sciences, El Paso, TX 79968,
AB: The St Elias orogen of southeast Alaska forms part of an actively deforming plate boundary corner. The corner accommodates the transition from a strike-slip lateral boundary to a convergent normal boundary. Oblique convergence of the Yakutat microplate into the corner generates early stage tectonic characteristics associated with other corner systems (e.g. Himalayan Eastern Syntaxis). In combination with the high relief, the extreme erosive processes of the region redistribute crustal material, partition tectonic strain, and influence the advection of deep crustal material. The evolution of the convergent corner is investigated using 3D numerical models and sandbox analog models. Preliminary model results indicate the deformation partitions into a narrow two-sided orogen along the lateral boundary. The pattern transitions into a wider zone of shortening bounded by inboard and outboard directed thrusts along the frontal boundary. The inclusion of erosion boundary conditions leads to nascent tectonic aneurysm behavior, involving increased strain localization and focused vertical advection of deep crustal material. Thermal models, using the 3D velocity field from these mechanical solutions, show a vertical deflection (towards the surface) of isotherms beneath the eroding region. Sensitivity of the aneurysm behavior is related to the efficiency of the imposed erosion rate (i.e. greater erosion rates led to greater bedrock uplift rates). Higher erosion rates are localized within zones containing major glacier systems in SE Alaska: Bering Glacier, Bagley Icefield, Malaspina Glacier, and Seward Glacier. Combined thermal/mechanical solutions identify the glacier valleys as rheological weakspots, defined by localized strain and differential advection of deep crustal material.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 8104 Continental margins: convergent
DE: 8177 Tectonics and climatic interactions
SC: Tectonophysics [T]
MN: 2007 Fall Meeting