Bengal Basin

This shallow marine sedimentary basin coupled with the Bengal Fan beneath the Bay of Bengal to form the largest sedimentary dispersal system known in the modern world.

[4] The Bengal basin was initiated during the breakup of Gondwanaland in the late Mesozoic Era.

The theories are:[4] The Bengal Basin has a thin, gently sloping alluvial cover in the western and northern parts, which thickens basin-ward.

It lies between the 'saddle' of the Garo-Rajmahal gap (submerged ridge) in the south and the Himalayan Front, which is part of the Indian states of West Bengal and Bangladesh.

The western sub-basin portion belonging to West Bengal is characterized by gentle eastward slopes and numerous step faults with small displacements.

The subsurface consists of layers of sandstone, red shale, grit and gravel.

The Dhananjaypur Formation at the base of the Rajmahal trap is identified as the early stage of subsidence on the eastern side of the west margin fault.

This sub-basin has deposits of rock from the Rajmahal and Jayanthi hills and alluvium from the Bhagirathi River.

[4][5] The southeastern sub-basin is bounded on the west by the Eocene shelf-break and the easternmost edge of the CTFB.