Milankovitch-paced erosion in the southern Central Andes

Fisher, G. Burch; Luna, Lisa; Amidon, William H.; Burbank, Douglas W.; Boer, Bas de; Stap, Lennert B.; Bookhagen, Bodo; Godard, Vincent; Oskin, M. E.; Alonso, Ricardo; Tuenter, E.; Lourens, Lucas Joost

doi:10.1038/s41467-023-36022-0

Cited by 4 publications

(2 citation statements)

References 87 publications

(173 reference statements)

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“…The southward migration of the ITCZ at this time led to heightened moisture availability throughout the Central Andes (Haselton et al, 2002;Broccoli et al, 2006;Vizy and Cook, 2007). Alluvial channels in semi-arid regions of the Central Andes are found to respond quickly to marked shifts in precipitation such as this (e.g., Schildgen et al, 2016;Tofelde et al, 2017), which also appear to drive phases of enhanced sediment evacuation to the foreland (Fisher et al, 2023).…”

Section: Impacts Of the Mid-pleistocene Transition On The Toro Basinmentioning

confidence: 96%

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Landscape response to tectonic deformation and cyclic climate change since ca. 800 ka in the southern Central Andes

Orr,

Schildgen,

Tofelde

et al. 2024

Preprint

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Abstract. Theory suggests that the response time of alluvial channel long-profiles to perturbations in climate is related to the magnitude of the forcing and the length of the system. Shorter systems may record a higher frequency of forcing compared to longer systems. Empirical field evidence that system length plays a role in the climate periodicity preserved within the sedimentary record is, however, sparse. The Toro Basin in the Eastern Cordillera of NW Argentina provides an opportunity to test these theoretical relationships as this single source-to-sink system contains a range of sediment deposits, located at varying distances from the source. A suite of eight alluvial fan deposits is preserved along the western flanks of the Sierra de Pascha. Farther downstream, a flight of cut-and-fill terraces have been linked to eccentricity-driven (100-kyr) climate cycles since ca. 500 ka. We applied cosmogenic radionuclide (10Be) exposure dating to the fan surfaces to explore (1) how channel responses to external perturbations may or may not propagate downstream, and (2) the differences in landscape response to forcing frequency as a function of channel length. We identified two generations of fan surfaces: the first (G1) records surface activity and abandonment between ca. 800 and 500 ka and the second (G2) within the last 100 kyr. G1 fans record a prolonged phase of net incision, which has been recognised throughout the Central Andes, and was likely triggered by enhanced 100-kyr global glacial cycles following the Mid-Pleistocene Transition. Relative fan surface stability followed, while 100-kyr cut-and-fill cycles occurred downstream, suggesting a disconnect in behaviour between the two channel reaches. G2 fans record higher frequency climate forcing, possibly the result of precessional forcing of climate (ca. 21/40-kyr timescales). The lack of a high-frequency signal farther downstream provides field support for theoretical predictions of a filtering of high-frequency climate forcing with increasing channel length. We show that multiple climate periodicities can be preserved within the sedimentary record of a single basin. Differences in the timing of alluvial fan and fluvial terrace development in the Toro Basin appears to be associated with how channel length affects fluvial response times to climate forcing as well as local controls on net incision, such as tectonic deformation.

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Section: Impacts Of the Mid-pleistocene Transition On The Toro Basinmentioning

confidence: 96%

“…Late Pleistocene sediment deposits are preserved ~140-160 km downstream from the headwaters of the Iruya Basin (22°S) of the northern Central Andes and record long eccentricity (400-kyr) cycles (Fisher et al, 2023). Crucially, only a single climate periodicity has been recorded in each these basins to date.…”

Section: Introductionmentioning

confidence: 99%

Landscape response to tectonic deformation and cyclic climate change since ca. 800 ka in the southern Central Andes

Orr,

Schildgen,

Tofelde

et al. 2024

Preprint

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Cosmogenic nuclide dating: Landscape evolution

Granger

2025

Encyclopedia of Quaternary Science

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Water discharge variations control fluvial stratigraphic architecture in the Middle Eocene Escanilla formation, Spain

Sharma

Whittaker

Watkins

et al. 2023

Sci Rep

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Ancient fluvial deposits typically display repetitive changes in their depositional architecture such as alternating intervals of coarse-grained highly amalgamated (HA), laterally-stacked, channel bodies, and finer-grained less amalgamated (LA), vertically-stacked, channels encased in floodplain deposits. Such patterns are usually ascribed to slower, respectively higher, rates of base level rise (accommodation). However, “upstream” factors such as water discharge and sediment flux also play a potential role in determining stratigraphic architecture, yet this possibility has never been tested despite the recent advances in the field of palaeohydraulic reconstructions from fluvial accumulations. Here, we chronicle riverbed gradient evolution within three Middle Eocene (~ 40 Ma) fluvial HA-LA sequences in the Escanilla Formation in the south-Pyrenean foreland basin. This work documents, for the first time in a fossil fluvial system, how the ancient riverbed systematically evolved from lower slopes in coarser-grained HA intervals, and higher slopes in finer-grained LA intervals, suggesting that bed slope changes were determined primarily by climate-controlled water discharge variations rather than base level changes as often hypothesized. This highlights the important connection between climate and landscape evolution and has fundamental implications for our ability to reconstruct ancient hydroclimates from the interpretation of fluvial sedimentary sequences.

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Milankovitch-paced erosion in the southern Central Andes

Cited by 4 publications

References 87 publications

Landscape response to tectonic deformation and cyclic climate change since ca. 800 ka in the southern Central Andes

Landscape response to tectonic deformation and cyclic climate change since ca. 800 ka in the southern Central Andes

Cosmogenic nuclide dating: Landscape evolution

Water discharge variations control fluvial stratigraphic architecture in the Middle Eocene Escanilla formation, Spain

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