Aerosol radiative forcing over tropical Indian Ocean: modulation by sea-surface winds

Abstract

To understand the magmatic processes originating in the deep mantle and their impact on the lower crustal level, the conspicuous gravity anomalies observed over the western part of Indian mainland and contiguous Arabian Sea were modelled, integrating the available seismic information. The unified 2D and subsequent 3D density modelling of the Narmada–Tapti region suggests a 15–20 km thick high-density (3.02 g cm^–3) accreted igneous layer at the base of the crust. The thickness of this layer varies from about 8 km near Multai to about 16 km beneath the central part and about 24 km beneath Navsari in the westernmost part of the Narmada–Tapti region. Similarly, a 7–11 km thick accreted igneous layer characterizes the Eastern Basin, including the Laxmi Ridge (LR) in the northeastern Arabian Sea. Thickness of this layer varies from about 4 km beneath the northwestern part to about 11 km beneath the central part of the LR. The extension of this layer towards the southeast and ultimate connection with the Chagos– Laccadive Ridge makes the western boundary of the magmatic crustal accretion along the west coast of India. The Konkan Coast, further down south, is also characterized by a ca. 3 km thick and about 40 km wide accreted igneous layer at the base of the crust along the coastline. It is suggested that this widespreading magmatic underplating along the western part of Indian land mass and adjoining Arabian Sea is the imprint of the Deccan magmatism caused by the deep mantle plume, when the northward migrating Indian plate passed over the Reunion hot spot.