Herman,F., Rhodes,E.J., Braun,J. and Heiniger,L.(2010): Uniform erosion rates and relief amplitude during glacial cycles in the Southern Alps of New Zealand, as revealed from OSL-thermochronology. Earth and Planetary Science Letters, 297, 183-189.

『OSL(光学的刺激ルミネッセンス)−熱年代測定法から明らかになった、ニュージーランドの南部アルプスにおける氷河サイクル中の均一な浸食速度と起伏量』


Abstract
 Glaciers and rivers control the shape of the high relief topography of mountain ranges However, their relative contribution in response to climatic oscillations and tectonic forcing and whether landscapes can reach equilibrium conditions during the Quaternary are still unclear. Here we introduce a new thermochronometer of exceptionally low closure temperature (ca. 30-35℃) based on Optically Stimulated Luminescence (OSL) dating and illustrate how it may be used to measure relief evolution and exhumation rates within the last glacial cycle in the Southern Alps of New Zealand, one of the most tectonically active orogens and an area that has experienced rapid, high magnitude climate changes. We find that exhumation rates have remained steady over the last glacial cycle and match rates observed at a million year timescale. This suggests that, despite an extreme exhumation rate of the order of 800 m in 100 ka, and the fact that in the last ca. 11-18 ka most hillslope sides have changed from U to V-shape valleys and have been dissected by debris-flows, landslides and rock avalanches, the mean exhumation rates have remained nearly constant. This may imply that tectonics, not climate, has a primary control on the rates of exhumation in tectonically active and wet mountain belts. On the contrary, tectonically active mountain ranges might not attain equilibrium on similar timescales in weathering and/or transport limited landscapes as, for example, in arid regions.

Keywords: OSL dating; thermochronology; glacial erosion; relief change; stochastic inversion; thermal modeling』

1. Introduction
2. OSL-thermochronology
3. Geological setting and sample collection
4. OSL measurements
5. Inversion of the thermochronological data to infer exhumation rates and the evolution of relief
6. Discussion
7. Conclusions
Acknowledgements
Appendix A. Supplementary data
References


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