GEOMORPHOLOGY , GEOLOGY AND MINERAL RESOURCES
| Geomorphology, Geology
and Mineral Resources
the state of Tripura represents the western fringe of typical “ridge and
valley” province of the late Tertiary fold mountain belt, commonly known
as Indo-Burman ranges (Purbanchal range). The general elevation varies
between 780 m in the north eastern part to 15 m in the western part above
mean sea level. Five prominent roughly north south trending anticlinal
strike ridges traverse the state from east to west; these are Jampui,
Sakhantlang, Longtarai, Athramura and Baramura. This strike ridges form
the watershed of the Meghna basin of Bangladesh fed by Khowai, Haora,
Juri, Manu, Dhalai, Deo, Longai, Muhuri, Feni and Gomoti rivers. Ten physiographic
units have been identified by the Geological Survey of India (1999) in
the State of Tripura which are given below Table-11.
Table-11 : Physiographic unit of Tripura
[Source: Mukherjee, Bhatacharrya and Sribastav, GSI, 1999]
The state of Tripura exhibit an wide array of sedimentary rocks characteristics of marine-mixed-fluvia type origin ranging age from upper most Oligocene (38 million years from present time) to Recent period. These sediments, according to GSI, have been laid down in the Surma basin during Tertiary age (which lasted for 65 million years) in an wide range of environmental conditions governed by local tectonic movement. Tectonically, the region now comprises a series of sub-parallel arquate, elongated, doubly plunging folds arrange in north south direction. These folds for anticlines separated by wide flat sinclines.
group of sediments during different geological age are shown in Table-12
surveys in the region reveal the presence of sub-surface flatus. The part
of Surma basin in Tripura Mizoram area lies in close proximity to the
Shillong plateau in the north and Aracan Yoma belt to the east. Tripura
is therefore located in seismically active zone; because of inherent character
of sediments of these areas even the minor shock during earthquake may
cause devastating particularly landslides (Mukherjee et.al., GSI, 1999)
The mineral resources of any state provide an avenue for economic development but the process of mining may have extensive impact on land, soil and water resources. The mining projects have as a consequence become a part of development sector requiring environmental clearance under Environmental Protection Act, 1986, EIA Notification 1994
In Tripura, the mineral resources are mainly glass sands, limestone, plastic clay and hard rock; all of these material are being used to a variable degree. However, the single most important resource in the state is oil and natural gas. ONGC or Oil and Natural Gas Commission has initiated massive exploration programme in the State, details of which are dealt later.
As for the other minerals, Table-13 provides an account of locations, deposit, current uses, etc. Details of clay deposit in Tripura has been dealt in the State of Environment Report for Tripura (1989). The impact of mining and quarrying of mineral resources in Tripura has so far been insignificant.
Table- 13 : Mineral Resource of Tripura
GSI Report 1982, 1999]
the total geographical area of Tripura, 76% can be marked as of “Tertiary”
origin and 24% belong to Quaternary period; none of these contain any
major mineral resource. A GSI Report of 1982 provide a list of Non-metallic
and metallic mineral vis-a-vis their location
or otherwise in Tripura (Table-14) indicating the poor profile.
Resource potential in Tripura
GSI Report 1982]
The current production of natural gas in estimated
at one million cubic meters per day. The available figure for 1990-91
to 1997-98 shows a fast increasing rate of production from 70 million
tonnes per year in 1990-91 to 2.7x in 8 years reaching 196 million tonnes