Vp. Rao et M. Veerayya, SUBMARINE TERRACE LIMESTONES FROM THE CONTINENTAL-SLOPE OFF SAURASHTRA-BOMBAY - EVIDENCE OF LATE QUATERNARY NEOTECTONIC ACTIVITY, Current Science, 71(1), 1996, pp. 36-41
Bathymetric and shallow seismic data from the continental slope off Sa
urashtra-Bombay indicate wide submarine terraces at 130, 145 and 170 m
and reefal structures at 320-360 m water depths, 10 cm thick slabs of
limestones are recovered from the 130 m depth terrace, Some of these
limestones consist of thin micrite layer on the top and a sandy laver
below and others are similar to calcarenites. They contain > 95% arago
nite and minor high- and low-magnesium calcite. Acicular aragonite cem
ents occur as isopachous crusts, Dissolution and clotting of aragonite
needles and drusy calcite in the interstices indicate cementation of
the limestones at intertidal conditions. The age of the limestones is
11,900 years BP. These imply that the 130 m depth terrace was at inter
tidal depths at about 12,000 years BP. The eustatic sea-level, however
, was at -90 m at 12,000 years BP. This disparity suggests neotectonic
activity and subsidence by about 40 m on the Saurashtra-Bombay region
some time after 12,000 years BP.