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Tectonic synthesis of the Olympic Mountains segment of the Cascadia wedge, using two-dimensional thermal and kinematic modeling of thermochronological ages

Batt, Geoffrey E. and Brandon, Mark T. and Farley, Kenneth A. and Roden-Tice, Mary (2001) Tectonic synthesis of the Olympic Mountains segment of the Cascadia wedge, using two-dimensional thermal and kinematic modeling of thermochronological ages. Journal of Geophysical Research B, 106 (B11). pp. 26731-26746. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20121109-141537734

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Abstract

A fully coupled two-dimensional kinematic and thermal model of a steady state accretionary wedge, constrained by an extensive data set of fission track and (U-Th)/He ages for apatite and zircon, is here used to investigate the development of the Olympic Mountains segment of the Cascadia accretionary wedge. The model has two main free parameters: ε_(max), the maximum rate of erosion for a generic erosion function operating at the top of the wedge, and α, the distribution of sedimentary accretion into the wedge. The best fit values for ε_(max) and α and their confidence limits are determined through an iterative search of parameter space. This study represents the first time that such inversion methods have been used to quantify the thermal-kinematic evolution of an accretionary wedge. Our results suggest that horizontal transport plays an important role in the exhumation trajectories experienced by material passing through the Cascadia wedge. At a 95% confidence interval, 80 to 100% of the sedimentary sequence from the subducting Juan de Fuca Plate has been accreted at the front of the wedge offshore of the Olympics over the past 14 m.y. This frontally accreted material must then traverse the entire width of the wedge prior to its eventual exposure in the Olympic forearc high. Assessed in this two-dimensional framework, the fission track and (U-Th)/He age data sets from the Olympic Mountains are all best fit by ε_(max) of 0.9–1.0 mm yr^(−1), despite variation in the timescales relevant to the three chronometers. This result supports the hypothesis that the Olympic Mountains segment of the Cascadia accretionary wedge has been in a flux steady-state since ∼14 Ma. The demonstration of a flux balance across the Cascadia margin also suggests that margin-parallel transport has not had a significant role in driving uplift of the Olympic Mountains.


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http://dx.doi.org/10.1029/2001JB000288 DOIUNSPECIFIED
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Additional Information:© 2001 by the American Geophysical Union. Received 10 August 2000; accepted 25 April 2001. This work was completed while G.B. was funded by a Damon Wells postdoctoral fellowship at Yale University. Detailed and thorough reviews of this manuscript by Peter Reiners and Phil Armstrong helped to significantly improve the clarity of our arguments.
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Yale University Damon Wells Postdoctoral Fellowship UNSPECIFIED
Issue or Number:B11
Record Number:CaltechAUTHORS:20121109-141537734
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121109-141537734
Official Citation:Batt, G. E., M. T. Brandon, K. A. Farley, and M. Roden-Tice (2001), Tectonic synthesis of the Olympic Mountains segment of the Cascadia wedge, using two-dimensional thermal and kinematic modeling of thermochronological ages, J. Geophys. Res., 106(B11), 26,731–26,746, doi:10.1029/2001JB000288
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35397
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:09 Nov 2012 22:59
Last Modified:03 Oct 2019 04:27

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