The Archipelago Group: current understanding
The geology and stratigraphy of the Archipelago Group are reviewed and new data presented to improve understanding. Major lithofacies are bioclastic limestones, bioturbated mottled marlstones, micritic limestones, trace fossil-bearing mudstones, quartzose sandstones and reworked volcanic material of Mio-Pliocene and Pleistocene age. The succession overlies the Pre-Neogene submarine fan turbidites and tectonic mélanges of ophiolite derivation and Mithakhari rocks, and is overlain by Quaternary deposits of late Pleistocene–Holocene age. The Neogene sequences were deposited in wave- and current-agitated shallow-marine intertidal and relatively deeper-water subtidal, nearshore and offshore shelfal environments. The existing stratigraphic framework is examined and suggestions made for improvement.
Figures & Tables
The Andaman–Nicobar Accretionary Ridge: Geology, Tectonics and Hazards
Rocks exposed across the hundreds of islands that belong to the 800 km long Andaman–Nicobar archipelago provide a condensed window into the active subduction zone that separates the India–Australia plate from the over-riding Burma–Sunda plate. Despite a strategic and seismically active location the Andaman-Nicobar ridge has seen comparatively little research. This Memoir provides the first detailed and comprehensive account of geological mapping and research across the island chain and adjacent ocean basins. Chapters examine models of Cenozoic rifting of the Andaman Sea and the regional tectonic and seismogenic framework. A detailed critical review of the Andaman–Nicobar stratigraphy, supported by new data, includes arc volcanism and a description of Barren Island, India’s only active volcano. Seismic history and hazards and the impacts of the 2004 earthquake and tsunami are also described. The volume ends with an examination of the region’s natural resources and hydrocarbon prospects.