Holocene Delta Evolution and Depositional Models of the Mekong River Delta, Southern Vietnam
Holocene Delta Evolution and Depositional Models of the Mekong River Delta, Southern Vietnam
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DOI：
10.2110/pec.05.83.0453
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
T. Ta;V. L. Nguyen;M. Tateishi;I. Kobayashi;Y. Saito
中科院分区：
文献类型：
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作者：
T. Ta;V. L. Nguyen;M. Tateishi;I. Kobayashi;Y. Saito
摘要：越南南部的湄公河三角洲是一个典型的潮汐和波浪主导的混合三角洲，形成于最近6 ~ 8天的广阔三角洲平原。该地区自末次海平面低洼以来的晚更新世-全新世序列由一个切谷填充物组成，包括晚更新世至早全新世的河流-河口沉积和全新世的三角洲沉积。三角洲沉积由早全新世沉积和中、晚全新世沉积组成。近3天来，前积三角洲由潮控三角洲演变为目前的波控与潮控混合三角洲，呈现出海岸环境剧变的特征。潮控三角洲的主要特征是陆下三角洲平原上红树林发育，沉积物跨岸扩散，沉积相受潮影响。该三角洲以潮波为主导，在陆下三角洲平原上为滩脊体系，沉积物呈滨岸扩散，三角洲前缘地形陡峭，河口近端沉积物粒度较粗，远端沉积物粒度较细。随着海平面的变化，河口海岸体系由河口向三角洲演化，潮汐主导的三角洲的形成标志着高地体系域的开始。
A BSTRACT : The Mekong River Delta in southern Vietnam is a typical mixed tide- and wave-dominated delta with a wide delta plain formed during the last 6 to 8 ky. The late Pleistocene–Holocene sequence in this region since the last sea-level lowstand is composed of an incised-valley fill, comprising late Pleistocene to early Holocene fluvial to estuarine sediments, and Holocene deltaic sediments. The deltaic sediments are composed of early Holocene aggradational sediments and progradational sediments of middle to late Holocene age. The progradational delta has evolved from a tide-dominated delta to the present mixed wave- and tide-dominated delta during the last 3 ky and shows a sudden regime shift of coastal environment. The tide-dominated delta was characterized by a well-developed mangrove forest on the subaerial delta plain, cross-shore sediment dispersal, and tide-influenced sedimentary facies. The tide- and wave-dominated delta exhibits a beach-ridge system in the subaerial delta plain, longshore sediment dispersal, and a steep delta-front topography, in which the sediments of the proximal river-mouth area are coarse-grained and those more distal are fine-grained. As river-mouth coastal systems evolve from estuaries to deltas in response to sea-level changes, the formation of a tide-dominated delta marks the initiation of the highstand systems tract.