ASSIGNMENT
COURSE TITLE : GEOMORPHOLOGY AND TECTONICS
COURSE CODE : 108
TOPIC : ASSIGNMENT ON EVOLUTION OF BENGAL BASIN IN
PERSPACTIVE OF GEOMORPHOLOGY AND TECTONICS
SUBMITTED TO : MOMTAHINA MITU
LECTURER,
DEPARTMENT OF COASTAL STUDIES AND DISASTER MANAGEMENT
UNIVERSITY OF BARISAL
SUBMITTED BY ,
NAME :NAZRIL EAHSAN RAHIM
ROLL : 230203015
DEPARTMENT : COASTAL STUDIES AND DISASTER MANAGEMENT
SESSION :2022-23
YEAR: 1st
DATE :30/11/2024
ASSIGNMENT ON EVOLUTION OF BENGAL
BASIN IN PRESPECTIVE OF
GEOMORPHOLOGY AND TECTONICS .
Introduction
The Bengal Basin is one of the largest sedimentary basin in the world . The term Bengal
basin is used to describe geological structure of Bengal region's sedimentary basin.It is spread
across the Indian states of West Bengal and Bangladesh. The Bengal Basin has an abundance
of natural gas. Natural gas is produced in Bangladesh. Also, large reserves of crude oil have
been discovered in West Bengal.The evolution of the Bengal basin began with the rise of the
Himalayas and the collision of the Indo-Eurasian plate. The Bay of Bengal delta and coastal
land are the result of this evolution.This assignment explores the formation, development,
and current geomorphological and tectonic features of the Bengal Basin.
Geographical Overview of Bengal Basin
Bengal Basin is situated towards the north-eastern part of Indian Peninsula in the state of West
Bengal, lies tentatively between Latitudes 25°-20°30’ and Longitude 87°30 – 90° 30 and falls
in the West Bengal state of India and Bangladesh. From the geological standpoint the Bengal
Basin,in the eastern part of the Indian subcontinent, occupies a vital geographic position at the
junction of three interacting plates namely the Great India, Burma and Tibetan (Eurasian)
Plates. The basin is bordered by the Himalayan Ranges and the Shillong Massif to the north,
the Indian shield to the west and the Arakan-chin fold system of the Indo-Burma Ranges to the
east. Towards south the basin is open to Bay of Bengal.The basin is characterized by a
unique.set of geological parameters making it a prolific hydrocarbon-bearing region with an
area of about 200000 km square.
Tectonic Framework of Bengal Basin
The Bengal Basin is believed to have evolved largely over a remnant ocean basin and rifted
continental margin of eastern India (Graham et al. 1975), with at least its northern northwestern
portion underlain by continental crust (khan and Agarwal, 1993) and southern and southeastern
part underlain by ocean crust.
trending Himalayas and
-south trending Indo-Barman
Fold Belt with the CTFB as its westward extension.
e beginning of Miocene because the
continuing oblique subduction of Indian plate beneath Burma plate.
-tectonic provincesa)
Passive to extensional cratonic margin in the west, the stable shelf province
1. The central Deep Basin Province or the remnant Basin
2. The subduction related orogen in the east, the Chittagong-Trip
Depositional Pattern & Sedimental History
The Dhananjaypur Formation deposition marked the beginning of subsidence in the Bengal
Basin along the Basin Margin Fault, followed by the Bolpur and Ghatal Formations under
varying depositional conditions. Palaeocene clastics of the Jalangi Formation revealed
estuarine influences. Geophysical studies indicate faults creating horsts and grabens,
influencing sediment geometry. Cretaceous sediments in the Baidyapur Depression show
basin-ward thickening, contrasting with flat-lying Eocene layers. Middle to late Eocene
subsidence caused marine transgression and deposition of Sylhet Limestone and Kopili Shale.
The late Eocene witnessed a regression of the sea, with similar sedimentary evolution in the
Shelf and Deep Basin. The Sylhet Trough, a key depositional area, records increasing
terrigenous sediment supply from Eocene to Miocene. Miocene saw alternating sandstone-
shale deposition, transitioning to estuarine and fluvial conditions by the Pliocene. The Late
Pliocene basin became sediment-starved. Early Pleistocene sedimentation was restricted to the
eastern basin, followed by complete Holocene alluvial coverage after sea regression.
Tectonic Evolution Phases
The evolution of the Bengal Basin can be divided into several tectonic phases:
Pre-Rift and Syn-Rift Stages: The basin's initial development began with rifting
associated with the break-up of the Gondwana supercontinent. These stages set the
groundwork for future sedimentary processes and tectonic structures within the basin .
Collision Phases: The basin has undergone multiple collision phases, both soft and
hard, related to the collision of the Indian plate with the surrounding plates. This
process has resulted in substantial sediment accumulation and complex structural
formations, particularly in the eastern and northern regions of the basin .
Ongoing Compression: Current tectonic activity is characterized by the ongoing
compression of the Indian plate beneath the Burmese tectonics. This leads to active
fold and thrust belt formations, as well as the development of strike -slip faults that
significantly alter the region’s topology .
Structural Characteristics of Bengal Basin
The structural characteristics of the Bengal Basin are deeply influenced by its tectonic
activities. These include:
Fold and Thrust Belts: Notable features include the Indo-Burmese ranges that exhibit
complex folding and faulting patterns arising from tectonic compressions .
Strike-Slip Fault Zones: The basin also contains significant strike-slip fault zones
that accommodate lateral movements resulting from tectonic collisions .
Geomorphological processes in the Bengal Basin
Geomorphological processes in the Bengal Basin predominantly involve sedimentation and
erosion, heavily influenced by the monsoonal regime of the region. The Ganges-Brahmaputra-
Meghna river system plays a critical role in shaping the geomorphology of the basin, acting as
a significant sediment transport mechanism . Sediments derived from the erosion of the
Himalayas are deposited throughout the basin, contributing to its extensive deltaic formations.
The delta has further evolved due to intricate interactions between tidal forces and river
dynamics, resulting in a complex network of channels and floodplains that are continually
reshaped by sediment input and sea-level fluctuations. These processes have created a highly
dynamic environment, leading to rapid changes in landforms, sediment distribution, and
ecological systems.
conclusion
In summary, the Bengal Basin's evolution is a multifaceted narrative of tectonic movements
and geomorphological processes. The intricate relationship between these elements continues
to influence the basin's landscape, sedimentation patterns, and ecological diversity, making it
a significant focus for ongoing geological and environmental research.
This comprehensive perspective on the Bengal Basin showcases the need for further
investigations into its stratigraphy and the impacts of anthropogenic activities amid changing
climatic conditions.
The information provided reflects a synthesis of the geomorphological and tectonic dynamics
at play in the evolution of the Bengal Basin, contributing to a broader understanding of this
critical geographic and geologic region.
Refference
Ashit Baran Roy,Tectonic Framework and Evolutionary history of the
Bengal Basin , http/www.researchgate.net
http//www.en.banglapedia.org
http//www.academia.edu
