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Lithology, monsoon and sea-surface current control on provenance, dispersal and deposition of sediments over the Andaman continental shelf

DRS at CSIR-National Institute of Oceanography

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Title Lithology, monsoon and sea-surface current control on provenance, dispersal and deposition of sediments over the Andaman continental shelf
 
Creator Damodararao, K.
Singh, S.K.
Rai, V.K.
Ramaswamy, V.
Rao, P.S.
 
Description Sediments deposited on the Northern and Eastern Andaman Shelf along with a few sediments from the Irrawaddy and the Salween Rivers are studied for their elemental, Sr and Nd concentrations and their isotope composition to identify their sources, constrain their transport pathways and assess the factors influencing the erosion in the catchment and their dispersal and deposition over the Andaman Shelf region. Major elemental compositions of the shelf sediments suggest mafic lithology such as ophiolites and ultrabasic rocks in the Irrawaddy drainage and over Indo � Burman � Arakan (IBA) ranges as their dominant source. 87Sr/86Sr ratios in sediments of the Northern and Eastern Andaman Shelf range between 0.712245 and 0.742183 whereas, εNd varies from -6.29 to -17.25. Sediments around Mergui have the highest 87Sr/86Sr and the lowest εNd values. Sr and Nd isotope composition of these sediments along with that in the potential sources suggest four major sources of these sediments to the Andaman Shelf, (i) the Irrawaddy River, (ii) the Salween River, (iii) Rivers draining the IBA ranges and (vi) Rivers draining the Western/Central granitic ranges of the Southern Myanmar and Western Thailand such as the Tavoy and the Tanintharyi Rivers. Erosion in the catchment is controlled by the precipitation and topography. Intensely focused precipitation over the higher relief of the western slopes of the IBA and western/central granitic ranges causes higher erosion over this mountainous region, supplying huge sediments through the Kaladan, Irrawaddy, Salween, and the Tanintharyi Rivers to the western Myanmar Shelf, Northern, and Eastern Andaman Shelves respectively. The majority of the sediments produced in the drainage are delivered to the shelf during the south-west monsoon which is dispersed eastward by sea-surface circulation from the mouth of the Irrawaddy Rivers towards the Gulf of Martaban and further southward. The Andaman Shelf receives very little sediment, if any, from the Ganga-Brahmaputra Delta. Higher erosion over the Western/Central granitic belt of the Southern Myanmar and Western Thailand and its importance in delivering sediments to the Eastern Andaman Shelf around the Mergui Archipelago are highlighted for the first time in this study.
 
Date 2017-03-10T09:29:01Z
2017-09-30T03:12:38Z
2017-03-10T09:29:01Z
2017-09-30T03:12:38Z
2016
 
Type Journal Article
 
Identifier Frontiers in Marine Science, vol.3; 2016; No.118 doi.org/10.3389/fmars.2016.00118
2296-7745
http://drs.nio.org/drs/handle/2264/7690
 
Language en
 
Relation Front Mar Sci
NON-SCI
 
Publisher Lausanne, Switzerland : Frontiers Media