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Aridity-induced Miocene canyon incision in the Central Andes

F. J. Cooper, B. A. Adams, J. D. Blundy, Kenneth A. Farley, R. E. McKeon and A. Ruggiero
Aridity-induced Miocene canyon incision in the Central Andes
Geology (Boulder) (August 2016) 44 (8): 675-678


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 approximately 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.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 44
Serial Issue: 8
Title: Aridity-induced Miocene canyon incision in the Central Andes
Affiliation: University of Bristol, School of Earth Sciences, Bristol, United Kingdom
Pages: 675-678
Published: 201608
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 30
Accession Number: 2016-069350
Categories: StratigraphyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2016221
Illustration Description: illus. incl. sketch map
S20°00'00" - S20°00'00", W69°30'00" - W69°30'00"
Secondary Affiliation: University of Tubingen, DEU, GermanyCalifornia Institute of Technology, USA, United StatesBHP Billiton, CHL, Chile
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201633
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