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Late Pleistocene landscape evolution in south-central Chile constrained by luminescence and stable cosmogenic nuclide dating

Katrin Rehak, Samuel Niedermann, Frank Preusser, Manfred R. Strecker and Helmut P. Echtler
Late Pleistocene landscape evolution in south-central Chile constrained by luminescence and stable cosmogenic nuclide dating
Geological Society of America Bulletin (July 2010) 122 (7-8): 1235-1247

Abstract

Landscapes in tectonically active regions develop in response to a complex interplay between rapid tectonic deformation and surface processes. In order to understand the evolution of these environments and distinguish between the different factors, it is fundamental to identify and quantify geomorphic processes and rates on different time scales. The forearc of south-central Chile provides an ideal setting to elucidate the response of surface processes to climatic and tectonic forcing. However, in contrast to northern Chile, this region has attracted little attention due to difficulties in quantifying the age of geomorphic surfaces. We use luminescence and stable cosmogenic nuclides ( (super 3) He, (super 21) Ne) on conglomeratic units in the Central Depression and fluvial valley fills in the Coastal Cordillera to constrain exposure and burial ages of these units that form major landscape elements in the southern Chilean forearc. Our data indicate that disturbances in the drainage network are controlled by local uplift, which may be caused by deformation above an active blind thrust. In the Coastal Cordillera, local short-term uplift rates reach a minimum of 0.27 mm a (super -1) and are on the same order as late Quaternary minimum incision rates of 0.15 mm a (super -1) to 0.43 mm a (super -1) . The valley fills in the Coastal Cordillera have depositional ages of 80 ka and 255 ka, respectively. Exposure ages of the extensive alluvial surfaces in the Central Depression cluster between 135 ka and 175 ka and between 240 ka and 280 ka. Hence, the deposition of these surfaces broadly coincides with marine isotope stages (MIS) 6 and 8 and appears to be climatically driven.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 122
Serial Issue: 7-8
Title: Late Pleistocene landscape evolution in south-central Chile constrained by luminescence and stable cosmogenic nuclide dating
Affiliation: Universitaet Potsdam, Institut fuer Geowissenschaften, Golm, Federal Republic of Germany
Pages: 1235-1247
Published: 201007
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 91
Accession Number: 2010-050197
Categories: Quaternary geologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2010045
Illustration Description: illus. incl. sect., 3 tables, geol. sketch map
S38°30'00" - S37°30'00", W73°30'00" - W73°00'00"
Secondary Affiliation: Helmholtz-Zentrum Potsdam, DEU, Federal Republic of GermanyUniversitaet Bern, CHE, Switzerland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, 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: 201027
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