Significance of Peat on the Western Continental Shelf of India

Peat layers 2 to 30 cm in thickness, 22 to 46 m below present sea level, are found along the inner shelf of India, up to 27 km from the coast. They are rich in plant debris, organic carbon and sulfur. These organic-rich layers are not sedimentary deposits. Lack of favourable substrates, absence of sheltered habitats, high energy physical enVironments, and a very rapid sea level rise during early Holocene indicate an unfavourable paleogeography and adverse oceanographic conditions for mangrove development and in situ peat formation. On the contrary, significant siliciclastic minerals, lithogenous elements and type III kerogen suggest a continental origin of peat. Restricted thickness, limited lateral distribution, absence of matted structures and laminated deposition imply transport of organics. Anomalous ages of wood with respect to present sea level are evidences of sediment reworking. Hence, peats on the continental shelf are not transgressive deposits.