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Toothpaste lava from the Barren Island volcano (Andaman Sea)

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Title Toothpaste lava from the Barren Island volcano (Andaman Sea)
 
Creator SHETH, HC
RAY, JS
KUMAR, A
BHUTANI, R
AWASTHI, N
 
Subject INDIAN-OCEAN
GROOVED LAVA
MOUNT-ETNA
FLOW-FIELD
EMPLACEMENT
CLASSIFICATION
PAHOEHOE
BASALT
HAWAII
TUMULI
volcanism
lava flow
basalt
toothpaste lava
Barren Island
Andaman Sea
 
Description Toothpaste lava is a basaltic lava flow type transitional between pahoehoe and aa and has been described from Paricutin, Kilauea and Etna volcanoes. Here we describe a spectacular example of toothpaste lava, forming part of a recent (possibly 1994-95) aa flow on the active volcano of Barren Island (Andaman Sea). This flow of subalkalic basalt shows abundant squeeze-ups of viscous toothpasate lava near its entry into the sea. The squeeze-ups are sheets and slabs, up to several meters across and tens of centimeters thick, extruded from boccas. They are often prominently curved, have striated upper surfaces with close-spaced, en echelon linear ridges and grooves, broad wave-like undulations perpendicular to the striations, and sometimes, clefts. Textural, geochemical, and Sr-Nd isotopic data on the squeeze-ups and the exposed aa flow core indicate very crystal-rich, viscous, and isotopically very homogeneous lava. We envisage that a greatly reduced speed of this viscous flow at the coastline, possibly aided by a shallowing of the basal slope, led to lateral spreading of the flow, which caused tension in its upper parts. This, with continued (albeit dwindling) lava supply at the back, led to widespread tearing of the flow surface and extrusion of the squeeze-ups. The larger slabs, while extruding in a plastic condition, curved under their own weight, whereas their surfaces experienced brittle deformation, forming the en echelon grooves. The extruded, detached, and rotated sheets and slabs were carried forward for some distance atop the very slowly advancing aa core, before the flow solidified. (C) 2011 Elsevier B.V. All rights reserved.
 
Publisher ELSEVIER SCIENCE BV
 
Date 2012-06-26T07:34:08Z
2012-06-26T07:34:08Z
2011
 
Type Article
 
Identifier JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH,202(1-2)73-82
0377-0273
http://dx.doi.org/10.1016/j.jvolgeores.2011.01.006
http://dspace.library.iitb.ac.in/jspui/handle/100/14147
 
Language English