Title: Late Quaternary Tectonics, Incision, and Landscape Evolution of the Calchaquí River Catchment, Eastern Cordillera, NW Argentina

Abstract

Unraveling the relative impacts of climate, tectonics, and lithology on landscape evolution is complicated by the temporal and spatial scale over which observations are made. We use soil and desert pavement classification, longitudinal river profiles, ¹⁰Be–derived catchment mean modern and paleo–erosion rates, and vertical incision rates to test whether, if we restrict our analyses to a spatial scale over which climate is relatively invariant, tectonic and lithologic factors will dominate the late Quaternary landscape evolution of the Calchaquí River Catchment, NW Argentina. We find that the spatial distribution of erosion rates, normalized channel steepness indices, and concavity indices reflect active tectonics and lithologic resistance. Knickpoints are spatially coincident with tectonic and/or lithologic discontinuities, indicating local base–level control by faulting. Catchment mean erosion rates, ranging from 22.5 ± 2.6 to 121.9 ± 13.7 mm/kyr, and paleo–erosion rates, ranging from 56 ⁺⁴³/ _–19 to 105 ⁺⁶⁰/ _–33 mm/kyr, are similar, possibly suggesting that Quaternary climate changes have not had a strong enough influence on erosion rates to be detected using cosmogenic ¹⁰Be. However, punctuated abandonment of pediment and strath terraces at 43.6 ^+15.0/ _–11.6, 91.2 ^+54.2/ _–22.2, and 151 ^+92.7/ _–34.1 ka and disparities between vertical incision rates and catchment mean erosionmore » rates could suggest periods of landscape transience, possibly reflecting climate cyclicity. Furthermore, our results emphasize the role of tectonic uplift and lithologic contrasts in shaping long–term erosion rates and channel morphology at the relatively local scale of the Calchaqui River Catchment, in contrast to regional–scale studies which find precipitation to exert the dominant control.« less

Authors:

McCarthy, James A. ^[1]; Schoenbohm, Lindsay M.  ^[1];

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Bierman, Paul R.  ^[2];

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Rood, Dylan  ^[3];

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Hidy, Alan J.  ^[4]

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+ Show Author Affiliations

1. Univ. of Toronto, ON (Canada)
2. Univ. of Vermont, Burlington, VT (United States)
3. Imperial College London, London (United Kingdom)
4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Publication Date:

2019-07-09

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1558859

Report Number(s):

LLNL-JRNL-666920
Journal ID: ISSN 2169-9003; 788396

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Earth Surface

Additional Journal Information:

Journal Volume: 124; Journal ID: ISSN 2169-9003

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Eastern Cordillera; longitudinal river profile analysis; 10Be catchment mean erosion rates; landscape evolution; climate and tectonics