Rapid Glacial Erosion at 1.8 Ma Revealed by ^4He/^3He Thermochronometry
Abstract
Alpine glaciation and river incision control the topography of mountain ranges, but their relative contributions have been debated for years. Apatite ^(4)He/^(3)He thermochronometry tightly constrains the timing and rate of glacial erosion within one of the largest valleys in the southern Coast Mountains of British Columbia, Canada. Five proximate samples require accelerated denudation of the Klinaklini Valley initiating 1.8 ± 0.2 million years ago (Ma). At least 2 kilometers of overlying rock were removed from the valley at ≥5 millimeters per year, indicating that glacial valley deepening proceeded ≥6 times as fast as erosion rates before ∼1.8 Ma. This intense erosion may be related to a global transition to enhanced climate instability ∼1.9 Ma.
Additional Information
© 2005 American Association for the Advancement of Science. Received for publication 8 August 2005; accepted for publication 7 November 2005. We thank G. Woodsworth for assistance in sample collection and providing access to the Digital Elevation Model used in Fig. 1 through collaboration with the Geologic Survey of Canada. We also thank J. M. Sisterson for help with the proton irradiation, L. M. Hedges for help with sample preparation, and M. S. Densmore. This work was supported by NSF grants EAR-0408526 and 0309779.Attached Files
Supplemental Material - Shuster.SOM.pdf
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Additional details
- Eprint ID
- 35581
- DOI
- 10.1126/science.1118519
- Resolver ID
- CaltechAUTHORS:20121120-142240847
- EAR-0408526
- NSF
- EAR-0309779
- NSF
- Created
-
2012-11-21Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences