Glacial catchment erosion from detrital zircon (U-Th)/He thermochronology
- 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 degrees 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 thatAlpine 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 degrees 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.…
Author details: | Sarah FalkowskiORCiDGND, Todd EhlersORCiDGND, Andrea MadellaORCiDGND, Christoph GlotzbachORCiDGND, Viktoria GeorgievaORCiDGND, Manfred StreckerORCiDGND |
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DOI: | https://doi.org/10.1029/2021JF006141 |
ISSN: | 2169-9003 |
ISSN: | 2169-9011 |
Title of parent work (English): | GR / AGU, American Geophysical Union: Earth surface |
Subtitle (English): | Patagonian Andes |
Publisher: | Wiley |
Place of publishing: | Hoboken, NJ |
Publication type: | Article |
Language: | English |
Date of first publication: | 2021/10/11 |
Publication year: | 2021 |
Release date: | 2024/04/11 |
Tag: | Leones Glacier; Northern Patagonian Icefield; ZHe tracer thermochronology; glacial erosion; grain; sediment production; size fractions |
Volume: | 126 |
Issue: | 10 |
Article number: | e2021JF006141 |
Number of pages: | 26 |
Funding institution: | German Research Society (DFG)German Research Foundation (DFG) [EH 329/18-1, STR 373/37-1]; Chilean Government FONDECYT Postdoctoral Grant 2020 [3200375]; Projekt DEAL |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
DDC classification: | 5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften |
Peer review: | Referiert |
Publishing method: | Open Access / Hybrid Open-Access |
License (German): | CC-BY-NC - Namensnennung, nicht kommerziell 4.0 International |