A minimum age for the active Barren Island volcano, Andaman Sea

Barren Island of Andaman Sea is the only active volcano in the Indian subcontinent. While the volcano has erupted sporadically many times over the last ∼70 ka, it is not known when it formed and breached the sea surface. To provide estimates for the timing of these events, we dated two tephra (ash)...

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Bibliographic Details
Published in:Current science (Bangalore) 2013-04, Vol.104 (7), p.934-939
Main Authors: Ray, Jyotiranjan S., Pande, Kanchan, Awasthi, Neeraj
Format: Article
Language:English
Subjects:
Age
Earth sciences
Lava
Marine
Oceans
Plagioclase
Plate tectonics
Seas
SPECIAL SECTION: EARTH SCIENCES
Tephra
Volcanic ash
Volcanoes
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Summary:Barren Island of Andaman Sea is the only active volcano in the Indian subcontinent. While the volcano has erupted sporadically many times over the last ∼70 ka, it is not known when it formed and breached the sea surface. To provide estimates for the timing of these events, we dated two tephra (ash) layers older than 42 ka and generated by this volcanism in a previously studied marine sediment core collected ∼32 km southeast of the island using the newly established modern 40Ar–39Ar facility in India. The 40Ar–39Ar plateau ages of plagioclase separates from successive tephra layers at 310 and 375 cm are 1.8 ± 0.4 (2σ) Ma and 1.5 ± 1.8 (2σ) Ma respectively. We interpret the more robust age of 1.8 Ma as the time of crystallization of plagioclase grains. As this age is very much older than the depositional age of the tephra layer (∼61 ka), we infer that it represents the age of older rocks present in the plumbing system of the volcano that were blown out with later pyroclastic eruptions and therefore, sets a strict younger limit to the time of formation of the volcano.
ISSN:0011-3891