Petrology of the prehistoric lavas and dyke of the Barren Island,Andaman Sea,Indian Ocean |
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| Authors: | M A Alam D Chandrasekharam O Vaselli B Capaccioni P Manetti P B Santo |
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| Institution: | (1) Department of Earth Sciences, Indian Institute of Technology, 400 076 Bombay, Mumbai, India;(2) Department of Earth Sciences, University of Florence, 50121 Florence, Italy;(3) Institute of Volcanology and Geochemistry, University of Urbino, 61029 Urbino, Italy;(4) CNR-Institute of Geosciences and Earth Resources, 56124 Pisa, Italy |
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| Abstract: | Although Barren Island (Andaman Sea, Indian Ocean) witnessed several volcanic eruptions during historic times, the eruptions
that led to the formation of this volcanic island occurred mainly during prehistoric times. It is still active and currently
in the fumarolic stage. Its volcanic evolution appears to be characterized by a constructive phase with the piling up of lava
flows and scoria deposits and Strombolian activities, followed by a sudden collapse of the main cone. Deposits of a possible
caldera-forming eruption were not recognized earlier. After a period of peri-calderic hydromagmatic activity, whose deposits
presently mantle inner and outer caldera walls, a new phase of intracalderic Vulcanian activities took place. A prominent
dyke in the SE inner side of the caldera wall was recognized. Petrographically the lava flows and dyke are similar but they
differ in their chemical composition (viz., SiO2, MgO, Ni, Cr) significantly. Similarity in major, minor and trace element composition (viz., K/La, K/Nb, K/Rb, K/Ti ratios)
of these rocks together with Chondrite normalized trace element (Rb, Ba, Sr, P, Zr, Ti and Nb) and REE (La, Ce, Nd and Y)
patterns of the Barren Island prehistoric lava flows and dyke and low-K lavas of Sunda Arc indicates that Barren Island must
have evolved from a source similar to that of Sunda Arc lavas during the Quaternary Period. |
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| Keywords: | Barren Island lava flows dyke petrology Sunda Arc |
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