1300 KM LONG LATE PLEISTOCENE-HOLOCENE SHELF EDGE BARRIER-REEF SYSTEMALONG THE WESTERN CONTINENTAL-SHELF OF INDIA - OCCURRENCE AND SIGNIFICANCE

A detailed analysis of echosounding and side-scan sonar data collected from the western continental margin of India has revealed the presenc e of prominent shelf edge reefs, concentrated mostly on the central an d 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). Morp hologically, they may be classified into (1) simple and (2) complex ty pes. The former are single and broad or narrow (av. width 350 m), whil e the latter are generally massive (av. width 950 m) with several supe rimposed peaks. Sub-bottom profiles indicate the presence of paleolago ons. This reef system, more than 1000 km long, trends NNW-SSE i.e., pa rallel to subparallel to the present-day shoreline. It is surmised tha t coral/algal reef growth commenced with the advent of the Holocene tr ansgression and favorable antecedent topography, and continued until e arly Holocene. Subsequently, rapid sea level rise drowned the reefs. T he shelf edge reefs, therefore, are part of ''relict, submerged'' barr ier reef system and reflect late Pleistocene/early Holocene shoreline.