Article abstract
Nature Geoscience 1, 793 - 799 (2008)
Published online: 26 October 2008 | doi:10.1038/ngeo334
Subject Categories: Geomorphology | Palaeoclimate and palaeoceanography | Structural geology, tectonics and geodynamics
Quaternary tectonic response to intensified glacial erosion in an orogenic wedge
Aaron L. Berger1, Sean P. S. Gulick2, James A. Spotila1, Phaedra Upton3, John M. Jaeger4, James B. Chapman5, Lindsay A. Worthington2, Terry L. Pavlis5, Kenneth D. Ridgway6, Bryce A. Willems7 & Ryan J. McAleer1
Abstract
Active orogens are thought to behave as internally deforming critical-taper wedges that are in rough long-term equilibrium with tectonic influx and erosional outflux. Spatial and temporal variations in climate are therefore hypothesized to have a significant influence on denudation, topography and deformation of orogens, thereby affecting wedge taper. However, the impact of the most severe transition in Northern Hemisphere climate during the Cenozoic era—the onset of glaciation—has hitherto not been empirically documented. Here we analyse the spatial patterns of denudation and deformation, and their temporal variations, in the heavily glaciated St Elias orogen in southern Alaska. Low-temperature thermochronometry, thermokinematic modelling and offshore seismic reflection and borehole data suggest that the global-scale intensification of glaciation in the middle Pleistocene epoch enhanced glacier growth and caused ice streams to advance to the edge of the continental shelf. This led to focused denudation across the subaerial reaches of the orogen and burial of the actively deforming wedge toe by the eroded sediment. We propose that this climatically driven mass redistribution forced a structural reorganization of the orogen to maintain critical taper. Our empirical results thus support decades of numerical model predictions of orogenesis and provide compelling field evidence for the significant impact of climate change on tectonics.
- Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA
- Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, J. J. Pickle Research Campus, Austin, Texas 78758, USA
- Department of Geological Sciences, 5790 Edward T. Bryand Global Sciences Center, University of Maine, Orono, Maine 04469, USA
- Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA
- Department of Geological Sciences, U. Texas El Paso, El Paso, Texas 79968, USA
- Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907, USA
- Department of Geology and Environmental Geosciences, Northern Illinois University, 312 Davis Hall, Normal Road, DeKalb, Illinois 60115, USA
Correspondence to: Aaron L. Berger1 e-mail: alberger@vt.edu
Correspondence to: James A. Spotila1 e-mail: spotila@vt.edu
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