The Andaman Archipelago

Ray, Jyotisankar

doi:10.1007/978-94-017-8029-2_21

Cited by 2 publications

(2 citation statements)

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“…The subaerial portion of the ridge is made up of >500 islands, two of which are volcanic (Narcondam and Barren; Figure a). As mentioned above, most of these islands are surrounded by coral reefs since the LGM [ Awasthi et al ., ; Ray , ], which would not have formed if the sediment discharge was significant. In addition, there exist several underwater ridges, located to the east of these islands, which may obstruct sediment discharge.…”

Section: Probable Sediment Sources and Their Compositionmentioning

confidence: 99%

“…No study as yet has confirmed the existence of sediment dispersal from the BoB into the Andaman Sea, whereas the converse has been established [e.g., Ramaswamy et al ., ; Rao et al ., ]. Andaman Islands, located within the north‐eastern Indian Ocean (Figure ) also experience heavy rainfall during the SW and NE monsoons and the rocks exposed on it are highly weatherable akin to the IBA ranges; however, limited areal extent (< 5000 km 2 ), lack of ample drainage and presence of coral reefs/underwater ridges [e.g., Ray , ] make these islands a minor source of sediments.…”

Section: Introductionmentioning

confidence: 99%

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Provenance of the Late Quaternary sediments in the Andaman Sea: Implications for monsoon variability and ocean circulation

Awasthi

Ray

Singh

et al. 2014

Geochem. Geophys. Geosyst.

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We present a geochemical and Sr-Nd isotopic study on a sediment core collected from the Andaman Sea in an attempt to reconstruct the Late Quaternary weathering and erosion patterns in the watersheds of the river systems of Myanmar and understand their controlling factors. Age control is based on nine radiocarbon dates and d18 O stratigraphy. The rate of sedimentation was strongly controlled by fluctuations of the monsoon. We identify three major sediment provenances: (1) the Irrawaddy catchment, (2) the western slopes of the Indo-Burman-Arakan (IBA) mountain ranges and the Andaman Islands, and (3) the catchments of Salween and Sittang and the Bengal shelf, with the first two contributing 30-60% of the material. Enhanced contributions from juvenile sources and corresponding positive shifts of d 18 O are observed at seven time periods (11-14, 20-23, 36, 45, 53, 57, and 62 ka) of which five are synchronous with cooling of the northern hemisphere, suggesting a link between the changes in sediment provenances and the shifting of the locus of the summer monsoon, southward from the Himalayas, without substantial reduction in intensity. Our data, and that from other cores in the region suggest that an eastward moving surface current disperses sediments, derived from the Bengal shelf and western margin of Myanmar, from the eastern Bay of Bengal into the western Andaman Sea and that its strength has increased since the LGM. The existence of this current during the LGM implies that the Andaman Sea and the Bay of Bengal were well connected during the last glacial period.

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Section: Probable Sediment Sources and Their Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Provenance of the Late Quaternary sediments in the Andaman Sea: Implications for monsoon variability and ocean circulation

Awasthi

Ray

Singh

et al. 2014

Geochem. Geophys. Geosyst.

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Chapter 12 Inner-arc volcanism: Barren and Narcondam islands

Bandopadhyay¹

2017

Memoirs

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Barren and Narcondam are active and now extinct, respectively, volcanic islands that belong to the inner-arc volcanic belt that extends from Java in the east to Burma in the north. Modern eruptions on Barren Island have been exclusively scoria cone-forming Strombolian-type activity in contrast to historic (1787–32) eruptions that witnessed a switch from scoria cone activity to abundant basaltic lava flows. Prehistoric (late Pleistocene) eruptions were alternating effusive and explosive events. The prehistoric events formed a mafic stratovolcano (island) and the associated large eruptions produced a c. 2.0 km diameter crater at the centre of the stratocone. Barren Island lavas are mainly basalts and basaltic andesites, whereas Narcondam rocks are dacite-andesite-rhyolite and contain evidence of magma mixing of both mantle and crustal material. The types of volcanoes and volcanism associated with Barren and Narcondam have been attributed to differences in tectonic setting and the nature of the basement below the volcanoes. It is likely that continental or transitional crust exists below Narcondam, in contrast to oceanic lithosphere below Barren Island.

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The Andaman Archipelago

Cited by 2 publications

References 9 publications

Provenance of the Late Quaternary sediments in the Andaman Sea: Implications for monsoon variability and ocean circulation

Provenance of the Late Quaternary sediments in the Andaman Sea: Implications for monsoon variability and ocean circulation

Chapter 12 Inner-arc volcanism: Barren and Narcondam islands

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