TY  - JOUR
A1  - Falkowski, Sarah
A1  - Ehlers, Todd
A1  - Madella, Andrea
A1  - Glotzbach, Christoph
A1  - Georgieva, Viktoria
A1  - Strecker, Manfred
T1  - Glacial catchment erosion from detrital zircon (U-Th)/He thermochronology
BT  - Patagonian Andes
JF  - GR / AGU, American Geophysical Union: Earth surface
N2  - 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 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.
KW  - ZHe tracer thermochronology
KW  - glacial erosion
KW  - sediment production
KW  - grain
KW  - size fractions
KW  - Leones Glacier
KW  - Northern Patagonian Icefield
Y1  - 2021
U6  - https://doi.org/10.1029/2021JF006141
SN  - 2169-9003
SN  - 2169-9011
VL  - 126
IS  - 10
PB  - Wiley
CY  - Hoboken, NJ
ER  -