Glacial catchment erosion from detrital zircon (U‐Th)/he thermochronology: Patagonian Andes

Falkowski, S. , Ehlers, T. A. , Madella, A., Glotzbach, C., Georgieva, V. and Strecker, M. R. (2021) Glacial catchment erosion from detrital zircon (U‐Th)/he thermochronology: Patagonian Andes. Journal of Geophysical Research: Earth Surface, 126(10), e2021JF006. (doi: 10.1029/2021JF006141)

Abstract

Alpine glacial erosion exerts a first-order control on mountain topography and sediment production, but its mechanisms are poorly understood. Observational data capable of testing glacial erosion and transport laws in glacial models are mostly lacking. New insights, however, can be gained from detrital tracer thermochronology. Detrital tracer thermochronology works on the premise that thermochronometer bedrock ages vary systematically with elevation, and that detrital downstream samples can be used to infer the source elevation sectors of sediments. We analyze six new detrital samples of different grain sizes (sand and pebbles) from glacial deposits and the modern river channel integrated with data from 18 previously analyzed bedrock samples from an elevation transect in the Leones Valley, Northern Patagonian Icefield, Chile (46.7°S). We present 622 new detrital zircon (U-Th)/He (ZHe) single-grain analyses and 22 new bedrock ZHe analyses for two of the bedrock samples to determine age reproducibility. Results suggest that glacial erosion was focused at and below the Last Glacial Maximum and neoglacial equilibrium line altitudes, supporting previous modeling studies. Furthermore, grain age distributions from different grain sizes (sand, pebbles) might indicate differences in erosion mechanisms, including mass movements at steep glacial valley walls. Finally, our results highlight complications and opportunities in assessing glacigenic environments, such as dynamics of sediment production, transport, transient storage, and final deposition, that arise from settings with large glacio-fluvial catchments.

• Item Type: Articles
• Additional Information: The study was supported by the German Research Society (DFG) grant EH 329/18-1 to T. A. Ehlers, and STR 373/37-1 to M. R. Strecker. V. Georgie-va's co-authorship was supported by the Chilean Government FONDECYT Postdoctoral Grant 2020 Nº 3200375.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Falkowski, Dr Sarah and Ehlers, Professor Todd A.
• Authors: Falkowski, S., Ehlers, T. A., Madella, A., Glotzbach, C., Georgieva, V., and Strecker, M. R.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Journal of Geophysical Research: Earth Surface
• Publisher: Wiley
• ISSN: 2169-9003
• ISSN (Online): 2169-9011
• Published Online: 13 October 2021
• Copyright Holders: Copyright: © 2021 The Authors
• First Published: First published in Journal of Geophysical Research: Earth Surface 126(10): e2021JF006
• Publisher Policy: Reproduced under a Creative Commons licence
• Data DOI: 10.5880/fidgeo.2021.027