A 300 kyr record of past hydroclimate change from alluvial fans in the southern Central Andes
Abstract
Alluvial fans are hypothesised to record signals of past hydroclimate changes in their depositional chronologies and slopes. However, direct tests of this hypothesis have been limited due to challenges in precisely dating the responses of alluvial fans to past climate forcing. Here, we present a new chronology of alluvial-fan deposition at the Sierra de Aconquija in the southern Central Andes (27 S) spanning $300 kyr and based on 35 cosmogenic 10 Be-derived exposure ages and eight infrared-stimulated (IRSL) and optically stimulated luminescence (OSL) ages. The ages reveal that fan deposition was phased with past climate changes. Orbitally-forced weakening and strengthening of the South American Summer Monsoon coincided with fan aggradation during dry episodes and incision during wetter episodes, consistent with predictions from alluvial-channel models. These results are in precise agreement with independent palaeoclimate constraints spanning timescales of 10 3 to 10 5 years. Fan aggradationincision cycles record a predominant influence of precession-induced variations in precipitation, although climate shifts as rapid as 1 kyr also triggered incision, and fan architecture appears to be further modulated by orbital eccentricity cycles. Incision events on the fans coincide with the ages of moraines in the headwater catchments, including those formed during the Younger Dryas and Last Glacial Maximum. Furthermore, the fan chronology indicates dry conditions in the southern Central Andes during Heinrich Stadial 1, suggesting that enhanced precipitation during this episode was limited to more northerly latitudes. Our results demonstrate that climate change exerts a primary control on simple, source-to-sink sedimentary systems and show that alluvial fans can, in some cases, be utilised as terrestrial palaeoclimate archives with which the spatio-temporal variability of past climate changes can be constrained.
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BibTeX
@article{darcy2026record,
title = {{A 300 kyr record of past hydroclimate change from alluvial fans in the southern Central Andes}},
author = {Mitch K d'Arcy and Taylor F Schildgen and Stéphane Bonnet and Walter Duesing and Stefanie Tofelde and Duna C Roda‐boluda and Hella Wittmann and Jürgen Mey and Andrew S Murray and Ricardo N Alonso and Manfred R Strecker},
journal = {Earth Surface Processes and Landforms},
year = {2026},
month = nov,
doi = {10.1002/esp.70006},
url = {https://ut-toulouseinp.hal.science/hal-05852332v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - A 300 kyr record of past hydroclimate change from alluvial fans in the southern Central Andes
AU - Mitch K d'Arcy
AU - Taylor F Schildgen
AU - Stéphane Bonnet
AU - Walter Duesing
AU - Stefanie Tofelde
AU - Duna C Roda‐boluda
AU - Hella Wittmann
AU - Jürgen Mey
AU - Andrew S Murray
AU - Ricardo N Alonso
AU - Manfred R Strecker
PY - 2026
DA - 2026/11/04
JO - Earth Surface Processes and Landforms
DO - 10.1002/esp.70006
UR - https://ut-toulouseinp.hal.science/hal-05852332v1
AB - Alluvial fans are hypothesised to record signals of past hydroclimate changes in their depositional chronologies and slopes. However, direct tests of this hypothesis have been limited due to challenges in precisely dating the responses of alluvial fans to past climate forcing. Here, we present a new chronology of alluvial-fan deposition at the Sierra de Aconquija in the southern Central Andes (27 S) spanning $300 kyr and based on 35 cosmogenic 10 Be-derived exposure ages and eight infrared-stimulated (IRSL) and optically stimulated luminescence (OSL) ages. The ages reveal that fan deposition was phased with past climate changes. Orbitally-forced weakening and strengthening of the South American Summer Monsoon coincided with fan aggradation during dry episodes and incision during wetter episodes, consistent with predictions from alluvial-channel models. These results are in precise agreement with independent palaeoclimate constraints spanning timescales of 10 3 to 10 5 years. Fan aggradationincision cycles record a predominant influence of precession-induced variations in precipitation, although climate shifts as rapid as 1 kyr also triggered incision, and fan architecture appears to be further modulated by orbital eccentricity cycles. Incision events on the fans coincide with the ages of moraines in the headwater catchments, including those formed during the Younger Dryas and Last Glacial Maximum. Furthermore, the fan chronology indicates dry conditions in the southern Central Andes during Heinrich Stadial 1, suggesting that enhanced precipitation during this episode was limited to more northerly latitudes. Our results demonstrate that climate change exerts a primary control on simple, source-to-sink sedimentary systems and show that alluvial fans can, in some cases, be utilised as terrestrial palaeoclimate archives with which the spatio-temporal variability of past climate changes can be constrained.
SN - 0197-9337
SN - 1096-9837
ER -