Limited impact of Quaternary glaciations on denudation rates in Central Asia

Puchol, Nicolas; Charreau, Julien; Blard, Pierre‐Henri; Lavé, Jérôme; Dominguez, Stéphane; Pik, Raphaël; Saint‐Carlier, Dimitri; Team, Aster

doi:10.1130/b31475.1

Cited by 37 publications

(66 citation statements)

References 83 publications

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“…Samples for measurement of cosmogenic 10 Be were collected from sandstones and conglomerates exposed at the base of 3.5-to 6-m-high road cuts to minimize modern cosmogenic nuclide production that could skew paleo-erosion rate estimates. Our approach to estimating paleo-erosion rates in foreland sediments is similar to that originally described by Charreau et al (37) and also applied in more recent studies (38,39). Measured 10 Be represents the sum of at least three components:…”

Section: Study Area and Methodsmentioning

confidence: 99%

“…Because erosion rate in semiarid watersheds of the central Andes is primarily correlated with precipitation (36), transient excursions in erosion rate over <400,000-y timescales should be a robust proxy for paleoprecipitation. Erosion rates are estimated by measuring cosmogenic 10 Be in ancient fluvial sediments deposited in foreland basin sequences, which record the erosion rate in their source watersheds (37)(38)(39). This approach yields a powerful proxy because it integrates landscape processes over a large region (10 4 -10 5 km 2 ) and provides a continuous record that can be precisely dated using magnetostratigraphy and tephrachronology.…”

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confidence: 99%

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Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Amidon

Fisher

Burbank

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Although Earth’s climate history is best known through marine records, the corresponding continental climatic conditions drive the evolution of terrestrial life. Continental conditions during the latest Miocene are of particular interest because global faunal turnover is roughly synchronous with a period of global glaciation from ∼6.2–5.5 Ma and with the Messinian Salinity Crisis from ∼6.0–5.3 Ma. Despite the climatic and ecological significance of this period, the continental climatic conditions associated with it remain unclear. We address this question using erosion rates of ancient watersheds to constrain Mio-Pliocene climatic conditions in the south-central Andes near 30° S. Our results show two slowdowns in erosion rate, one from ∼6.1–5.2 Ma and another from 3.6 to 3.3 Ma, which we attribute to periods of continental aridity. This view is supported by synchrony with other regional proxies for aridity and with the timing of glacial ‟cold” periods as recorded by marine proxies, such as the M2 isotope excursion. We thus conclude that aridity in the south-central Andes is associated with cold periods at high southern latitudes, perhaps due to a northward migration of the Southern Hemisphere westerlies, which disrupted the South American Low Level Jet that delivers moisture to southeastern South America. Colder glacial periods, and possibly associated reductions in atmospheric CO2, thus seem to be an important driver of Mio-Pliocene ecological transitions in the central Andes. Finally, this study demonstrates that paleo-erosion rates can be a powerful proxy for ancient continental climates that lie beyond the reach of most lacustrine and glacial archives.

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Section: Study Area and Methodsmentioning

confidence: 99%

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confidence: 99%

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Amidon

Fisher

Burbank

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Magnetostratigraphic studies show that local rates of sediment accumulation have been relatively steady at about 0.2 mm year −1 over the last 10 Myr (Charreau et al ., , ; Lu et al ., , ). The erosion rate in the high range has been estimated to be between 0.1 and 1 mm year −1 in the last 9 Myr with an excursion to 2–2.5 mm year −1 at the onset of Quaternary glaciations according to cosmogenic isotope measurements in exposed piedmont deposits (Charreau et al ., ; Puchol et al ., ). Guerit et al .…”

Section: Geological Setting Of the North Piedmont Of The Eastern Tianmentioning

confidence: 97%

“…Magnetostratigraphic studies show that local rates of sediment accumulation have been relatively steady at about 0.2 mm year À1 over the last 10 Myr (Charreau et al, 2005(Charreau et al, , 2009Lu et al, 2010bLu et al, , 2013. The erosion rate in the high range has been estimated to be between 0.1 and 1 mm year À1 in the last 9 Myr with an excursion to 2-2.5 mm year À1 at the onset of Quaternary glaciations according to cosmogenic isotope measurements in exposed piedmont deposits (Charreau et al, 2011;Puchol et al, 2016). Guerit et al (2016) estimated erosion rates of around 0.135 mm year À1 for the last 300 kyr from the mass balance of 10 alluvial fans in the northern piedmont of the Eastern Tian Shan.…”

Section: Geological Setting Of the North Piedmont Of The Eastern Tianmentioning

confidence: 99%

Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate‐driven aggradation–incision cycles

et al. 2017

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Transient sediment storage and mixing of deposits of various ages during transport across alluvial piedmonts alters the clastic sedimentary record. We quantify buffering and mixing during cycles of aggradation-incision in the north piedmont of the Eastern Tian Shan. We complement existing chronologic data with 20 new luminescence ages and one cosmogenic radionuclide age of terrace abandonment and alluvial aggradation. Over the last 0.5 Myrs, the piedmont deeply incised and aggraded many times per 100 kyr. Aggradation is driven by an increased flux of glacial sediment accumulated in the high range and flushed onto the piedmont by greater water discharge at stadialinterstadial transitions. After this sediment is evacuated from the high range, the reduced input sediment flux results in fluvial incision of the piedmont as fast as 9 cm/yr and to depths up to 330 m. The timing of incision onset is different in each river and does not directly reflect climate forcing but the necessary time for the evacuation of glacial sediment from the high range. A significant fraction of sediments evacuated from the high range is temporarily stored on the piedmont before a later incision Accepted ArticleThis article is protected by copyright. All rights reserved.phase delivers it to the basin. Coarse sediments arrive in the basin with a lag of at least 7 to 14 kyrs between the first evacuation from the mountain and later basinward transport. The modern output flux of coarse sediments from the piedmont contains a significant amount of recycled material that was deposited on the piedmont as early as the Middle Pleistocene. Variations in temperature and moisture delivered by the Westerlies are the likely cause of repeated aggradation-incision cycles in the north piedmont instead of monsoonal precipitation. The arrival of the gravel front into the proximal basin is delayed relative to the fine-grained load and both are separated by a hiatus. This work shows, based on field observations and data, how sedimentary systems respond to climatic perturbations, and how sediment recycling and mixing can ensue.

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“…They identify a transient increase in paleoerosion rate at the onset of Northern Hemisphere continental glaciation approximately 2.5 Ma to 1.7 Ma, which they attribute to glacial modification of the sediment source region. However, follow‐up studies of more sections in central Asia did not replicate this result [ Puchol et al , ]. Val et al [] used paleoerosion rates from sediments exposed within the Argentine Precordillera convergent belt to show how the dynamics of river incision introduce lag between tectonic uplift and erosional response.…”

Section: Introductionmentioning

confidence: 99%

Steady ¹⁰Be‐derived paleoerosion rates across the Plio‐Pleistocene climate transition, Fish Creek‐Vallecito basin, California

et al. 2017

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Rates of erosion over time provide a valuable tool for gauging tectonic and climatic drivers of landscape evolution. Here we measure 10Be archived in quartz sediment from the Fish Creek‐Vallecito basin to resolve a time series of catchment‐averaged erosion rates and to test the hypothesis that aridity and increased climate variation after approximately 3 Ma led to an increase in erosion rates in this semiarid, ice‐free setting. The Fish Creek‐Vallecito basin, located east of the Peninsular Ranges in Southern California, is an ideal setting to derive a Plio‐Pleistocene paleoerosion rate record. The basin has a rapid sediment accumulation rate, a detailed magnetostratigraphic age record, and its stratigraphy has been exposed through recent, rapid uplift and erosion. A well‐defined source region of uniform lithology and low erosion rate provides a high, reproducible 10Be signal. We find that paleoerosion rates were remarkably consistent between 1 and 4 Ma, averaging 38 ± 24 m/Myr (2σ). Modern catchment‐averaged erosion rates are similar to the paleoerosion rates. The uniformity of erosion over the past 4 Myr indicates that the landscape was not significantly affected by late Pliocene global climate change, nor was it affected by a local long‐term increase in aridity.

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Limited impact of Quaternary glaciations on denudation rates in Central Asia

Cited by 37 publications

References 83 publications

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate‐driven aggradation–incision cycles

Steady ¹⁰Be‐derived paleoerosion rates across the Plio‐Pleistocene climate transition, Fish Creek‐Vallecito basin, California

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Limited impact of Quaternary glaciations on denudation rates in Central Asia

Cited by 37 publications

References 83 publications

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate‐driven aggradation–incision cycles

Steady 10Be‐derived paleoerosion rates across the Plio‐Pleistocene climate transition, Fish Creek‐Vallecito basin, California

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Steady ¹⁰Be‐derived paleoerosion rates across the Plio‐Pleistocene climate transition, Fish Creek‐Vallecito basin, California