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Exhumation of the central Wasatch Mountains, Utah: 1. Patterns and timing of exhumation deduced from low-temperature thermochronology data

Armstrong, Philip A. and Ehlers, Todd A. and Chapman, David S. and Farley, Kenneth A. and Kamp, Peter J. J. (2003) Exhumation of the central Wasatch Mountains, Utah: 1. Patterns and timing of exhumation deduced from low-temperature thermochronology data. Journal of Geophysical Research B, 108 (B3). Art. No. 2172. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20130419-114812746

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Abstract

The Wasatch Mountains are often cited as an example of normal fault growth and footwall flexure. They represent a tilted footwall at the edge of the Basin and Range extensional province, a major rift basin. Thus understanding the detailed spatial and elevation changes in coupled thermochronometer data, and how these changes can be interpreted, may aid in the analysis of thermochronometer data from other extensional regions around the world. We present a dense data set from the Cottonwood Intrusive Belt (CIB) of the Wasatch that includes apatite fission track (AFT), zircon fission track (ZFT), and apatite (U-Th)/He ages. ZFT, AFT, and apatite (U-Th)/He ages are 10, 5, and 3 Ma, respectively, adjacent to the Wasatch fault. AFT and (U-Th)/He ages increase slightly with distance east of the fault until about 15–20 km, where a more abrupt increase in these ages occurs at or near the Silver Fork-Superior fault zone. ZFT and AFT ages are concordant with 31–38 Ma pluton emplacement ages on the eastern side of range. Modeling of the data leads to the following interpretation: (1) Early cooling and ∼3–4 km of exhumation for the middle and eastern parts of the range occurred in the late Oligocene-middle Miocene. (2) Beginning at 10–12 Ma, the locus of exhumation shifted westward toward the present range front, where the rocks cooled from >200°C in the last 10–12 Myr. Our data and interpretations are consistent with a model in which the locus of faulting and exhumation shifted opposite the direction of tilt, similar to that predicted by rolling-hinge extensional models. However, this westward shift and rapid Miocene to recent exhumation may be a local effect superimposed on lower fault displacement and exhumation rates elsewhere along the Wasatch.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1029/2001JB001708DOIUNSPECIFIED
http://onlinelibrary.wiley.com/doi/10.1029/2001JB001708/abstractPublisherUNSPECIFIED
Additional Information:© 2003 American Geophysical Union. Received 11 December 2001; revised 27 September 2002; accepted 1 October 2002; published 29 March 2003. We thank W. Parry, R. Bruhn, B. Kowallis, and K. Constenius for supplying sample splits for this study and E. Reinert, L. Cannon, M. Perkins, and L. Hedges for help with sample collection and preparation. Discussions of Wasatch geology with J. Bartley, R. Bruhn, B. Kowallis, and K. Constenius are greatly appreciated. R. Donelick supplied the Cf-252 irradiations. This paper greatly benefited from reviews by R. Ketcham, S. Thompson, and Associate Editor J. Braun. Research was funded by NSF grant EAR-9805073 to Armstrong and Chapman.
Funders:
Funding AgencyGrant Number
NSFEAR-9805073
Subject Keywords:Wasatch Mountains, exhumation, fission track, helium dating
Issue or Number:B3
Record Number:CaltechAUTHORS:20130419-114812746
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130419-114812746
Official Citation:Armstrong, P. A., T. A. Ehlers, D. S. Chapman, K. A. Farley, and P. J. J. Kamp, Exhumation of the central Wasatch Mountains, Utah: 1. Patterns and timing of exhumation deduced from low-temperature thermochronology data, J. Geophys. Res., 108(B3), 2172, doi:10.1029/2001JB001708, 2003
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38040
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:23 Apr 2013 16:08
Last Modified:03 Oct 2019 04:53

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