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Origin and evolution of interdistributary delta plains; insights from Mekong River delta

Toru Tamura, Yoshiki Saito, V. Lap Nguyen, T. K. Oanh Ta, Mark D. Bateman, Dan Matsumoto and Shota Yamashita
Origin and evolution of interdistributary delta plains; insights from Mekong River delta
Geology (Boulder) (February 2012) 40 (4): 303-306

Abstract

The geometry of river deltas is considered to reflect the interplay of coastal processes, river discharge, and sediment supply. As approximately 25% of the world's population lives on deltaic lowlands, prediction of delta growth is critical. Knowledge of processes responsible for delta geometries is not well established, although such knowledge is critical for the risk management of land use and settlements on deltas. The Mekong River delta of southern Vietnam is one of the largest deltas in the world and offers a unique opportunity to understand the sedimentary evolution of mixed tide- and wave-dominated large river deltas. We constrained the three-dimensional sedimentary evolution of the delta plains, based on optically stimulated luminescence dating of beach ridges coupled with radiocarbon-dated sediment cores. Results show that the beach shoreline in the lower delta plain initiated ca. 3.5 ka by aggradation on basement shoals. The delta plain propagated laterally during the late Holocene, evolving from bars that resulted in asymmetric bifurcation of the river mouth. Asymmetry was caused by the southwestward longshore sediment drift enhanced by the winter monsoon. Bars were successively formed on the wider side of the bifurcated river mouths, and subsequently accreted seaward, being stabilized by tide effects to result in shore-perpendicular elongate delta plains. Our work, based on the Mekong delta, demonstrates for the first time that bar emergence is a key process in the long-term evolution of mixed tide- and wave-dominated deltas.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 40
Serial Issue: 4
Title: Origin and evolution of interdistributary delta plains; insights from Mekong River delta
Affiliation: National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan, Ibaraki, Japan
Pages: 303-306
Published: 20120228
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 26
Accession Number: 2012-037634
Categories: Geomorphology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2012087; accessed on March 22, 2012
Illustration Description: illus. incl. sect., sketch maps
Source Medium: WWW
N09°30'00" - N10°30'00", E105°40'00" - E107°00'00"
Secondary Affiliation: University of Sheffield, GBR, United KingdomVietnamese Academy of Science and Technology, VNM, VietnamChiba University, JPN, Japan
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: 201220

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