1300 km long late Pleistocene-Holocene shelf edge barrier reef system along the western continental shelf of India: Occurrence and significance

Abstract

A detailed analysis of echosounding and side-scan sonar data collected from the western continental margin of India has revealed the presence of prominent shelf edge reefs, concentrated mostly on the central and the southern parts. Their depth of occurrence varies between 85 and 136 m. The reefs are 1-12 m high and 0.1-2.6 km wide (av. 700 m). Morphologically, they may be classified into (1) simple and (2) complex types. The former are single and broad or narrow (av. width 350 m), while the latter are generally massive (av. width 950 m) with several superimposed peaks. Sub-bottom profiles indicate the presence of paleolagoons. This reef system, more than 1000 km long, trends NNW-SSE i.e., parallel to subparallel to the present-day shoreline. It is surmised that coral/algal reef growth commenced with the advent of the Holocene trangression and favorable antecedent topography, and continued until early Holocene. Subsequently, rapid sea level rise drowned the reefs. The shelf edge reefs, therefore, are part of "relict, submerged" barrier reef system and reflect late Pleistocene/early Holocene shoreline