Quench textures in pillow basalt from the Andaman-Nicobar Islands,Bay of Bengal,India

Tholeiitic pillow basalt from the South Andaman island, an integral part of the outer sedimentary arc of the Sunda-Burmese double chain arc system in the Bay of Bengal, is characterized by the occurrence of several morphologies of quenched crystals of plagioclase and pyroxene. Plagioclase shows a swallow tail, belt-buckle, rosette and closely spaced fan-spherulites pattern while pyroxene has elongate parallel chain, dendritic, spherulitic and finely ornamented feathery spherulitic habit. Most of these textures are identical to those reported from submarine basalts, lunar basalts, spinifex textured rocks and experimentally produced textures. The occurrence of these quench textures in the Andaman basalt suggests that they were formed by rapid cooling at 30–70°C/h in a submarine environment.