| dc.description.abstract | Seafloor surveys and sediment sampling during the INDEX (Indian Deep-Sea Environmental Experiment) studies in the Central Indian Basin, resulted in identification of Test and Reference Areas, as well of establishment of baseline conditions for Benthic Disturbance. The proposed disturbance site has flat topography and low slope angles (less than 1 degree), with thick sediment cover. (approx 40-60 m). Sediment is mainly of radiolarian ooze type, dark brown to light brown in colour, intensely mottled and bioturbated with high brown or greyish intercalations in the deeper layers. Predominantly belonging to `clay-silt' size, it comprises mainly of smectites and illites and is very poorly sorted. Various chemical paramters, e.g., pH, alkalinity, phosphate, nitrie and nitrate concentrations in porewaters do not show any trend indicating non-steady state. High natural water content (>350%), low bulk density and specific gravity, as well as low shear strength indicate that the sediments are loosely packed and have low compaction. Based on radiolarian fossil zonations, the biostratigraphic ages observed in majority of the cores show youngest radiolarian zone Buccinosphaecra invaginata in the top 30-35 cms and indicates that the stratification necessary for age determination is intact. This information is being used as baseline data for assessing the impact of sediment resuspension and redistribution as a result of the benthic disturbance caused at the site and the studies are underway to assess its impact in the benthic enviornment | |
