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|Title:||An optical luminescence chronology for late Pleistocene aeolian activity in the Colombian and Venezuelan Llanos Quaternary Research|
|Authors:||Carr, Andrew Stephen|
Armitage, S. J.
Berrio, J. C.
|Citation:||Quaternary Research, 2016, 85 (2), pp. 299-312|
|Abstract:||The lowland savannas (Llanos) of Colombia and Venezuela are covered by extensive aeolian landforms for which little chronological information exists. We present the first optically stimulated luminescence (OSL) age constraints for dunes in the Llanos Orientales of lowland Colombia and new ages for dunes in the Venezuelan Llanos. The dunes are fully vegetated and show evidence of post-depositional erosion. Ages range from 4.5 ± 0.4 to 66 ± 4 ka, with the majority dating to 10-27 ka (Marine Isotope Stage 2). Some dunes accumulated quickly during the last glacial maximum, although most were active 16-10 ka. Accretion largely ceased after 10 ka. All dunes are elongated downwind from rivers, parallel with dry season winds, and are interpreted as source-bordering features. As they are presently isolated from fluvial sediments by gallery forest it is proposed that activity was associated with a more prolonged dry season, which restricted gallery forest, leading to greater sediment availability on river shorelines. Such variability in dry season duration was potentially mediated by the mean latitude of the ITCZ. The cessation of most dune accretion after ca. 10 ka suggests reduced seasonality and a more northerly ITCZ position, consistent with evidence from the Cariaco Basin|
|Rights:||Copyright © 2015 University of Washington. Published by Elsevier Inc. All rights reserved. This manuscript version is made available after the end of the embargo period under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/|
|Description:||The file associated with this record is under a 12-month embargo from publication in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.|
|Appears in Collections:||Published Articles, Dept. of Geography|
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|Llanos OSL ages paper_revised_final_IRIS.pdf||Post-review (final submitted)||1.91 MB||Adobe PDF||View/Open|
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