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Aridity-induced Miocene canyon incision in the Central Andes

Cooper, F. J. and Adams, B. A. and Blundy, J. D. and Farley, K. A. and McKeon, R. E. and Ruggiero, A. (2016) Aridity-induced Miocene canyon incision in the Central Andes. Geology, 44 (8). pp. 675-678. ISSN 0091-7613. https://resolver.caltech.edu/CaltechAUTHORS:20160713-140128252

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Abstract

The relationship between the rise of the Andean mountain chain and the onset of aridity on its western margin is poorly understood. Canyon incision on both the eastern and western flanks of the chain is interpreted generally as a direct response to increased rock uplift, but may equally have been the result of climate change. Here we record some of the oldest canyon incision on the western Andean margin by tracking the downward migration of the local water table using (U-Th)/He hematite geochronology on vertical drill-core transects. Our data constrain the incision history of the Quebrada de Parca canyon in northern Chile from ca. 16 Ma to the present day. The erosional and topographic response of the Quebrada de Parca river suggests that incision was induced by a switch to a more arid climate in the middle Miocene, which reduced regional precipitation and river discharge. Geomorphic analysis of the modern river suggests that the Central Andes have gained only ∼700 m of elevation since incision began, and had therefore reached at least 50% of their current elevation by middle Miocene time. We thus conclude that the onset of aridity at ca. 16 Ma occurred subsequent to the main Andean uplift.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1130/G38254.1DOIArticle
http://geology.gsapubs.org/content/44/8/675PublisherArticle
http://geology.geoscienceworld.org/content/44/8/675PublisherArticle
Additional Information:© 2016 Geological Society of America. Manuscript received 5 January 2016; Revised manuscript received 19 June 2016; Manuscript accepted 23 June 2016; First published on July 12, 2016. This work was funded by BHP Billiton. We are grateful to Jean des Rivières for granting access to the drill core, the geologists at Cerro Colorado mine for assistance with sampling, Donny Hutton for logistical support in Chile, and Lindsey Hedges for help with the laboratory analyses. We thank Matthew Rossi for comments on an earlier version of the manuscript; Simon Lamb, Matthew Jungers, and an anonymous reviewer for their detailed and helpful reviews; and Jim Spotila for editorial handling.
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Funding AgencyGrant Number
BHP BillitonUNSPECIFIED
Issue or Number:8
Record Number:CaltechAUTHORS:20160713-140128252
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160713-140128252
Official Citation:Aridity-induced Miocene canyon incision in the Central Andes F.J. Cooper, B.A. Adams, J.D. Blundy, K.A. Farley, R.E. McKeon, A. Ruggiero Geology Aug 2016, 44 (8) 675-678; DOI: 10.1130/G38254.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69010
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:28 Jul 2016 17:38
Last Modified:03 Oct 2019 10:18

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