Monthly Average Temp., Humidity & Rain fall of
(Max=Maximum, Min=Minimum, Mean=Mean of
Temperature, all unit in Degree Celsius, Rain fall is of Monthly Total in
PHYSIOGRAPHY, GEOLOGY AND MINERAL RESOURCES
The major geomorphic features observed in the state are topographic highs
(hills) and depressions, valleys, flats and slopes sculptured on the surface in
a linear fashion. In Tripura the topographic highs and depressions are in all
cases coincident, respectively, with the anticlinal and synclinal structures of
the rock formation. A number of broad and elongated valleys, as for example,
Agartala-Udaipur-Sabrum, Khowai-Teliamura-Amarpur-Silachari etc. are located
between the north-south trending, parallel to sub- parallel high ranges
(topographic highs) such as the Baramura-Deotamura ranges, Atharamura ranges,
Langtari ranges, Shakan ranges, and the Jampui hill ranges. The main rivers are
the Khowai, Doloi, Manu, Jun and Langai flowing towards the north, and those
flowing towards west are the Gomati, Muhuri and Feni. The drainage patterns are
of dendnitic, parallel to sub-parallel and rectangular types.
The study of rocks of Tripura dates back to 1908 when H.C.
Dasgupta first classified the folded sedimentary rocks into 'Coal measures' and
'Tripura Group'. The rocks encountered in Tripura State range in age from Lower
Tertiary (40 million years old) to Recent (less than 1 million years old). These
sedimentary rocks are derived from the sediments that were deposited in a mobile
trough known as the Barail geosyncline. The shallowing of this large basin was
followed by the deposition of sediments in the continental slope-rise segments
and then by the deposition in unstable foredeep. The deposition in each type of
basin and environment is beautifully reflected in the rocks showing distinctive
characteristics. The continuity of deposition of the sediments is marked by
breaks known as unconformity, and deformational disturbances have been
beautifully recorded in the rocks and carefully demarcated by the geologists.
This geotectonic cycle finally ended by regional elevation of the platform and
uplift of the basin to give rise to the present geomorphic features.
Thus, the sedimentary rocks of Tripura can be divided
into 'Formations', 'Sub-Group' and 'Group' on the basis of their lithological
composition, depositional characteristic and structural features.
The oldest rocks of Tripura,
known as the Surma Group are characterised by repetitions of massive, well-
bedded sandstone and gray and olive shale in equal proportion at the bottom
followed upwards by repetitions of thinly laminated chiefly argillaceous rocks
like siltstone shale, mudstone, etc. The presence of features like current
bedding 'ripple-drift cross laminations', 'load-casts', 'turbidite structures',
'flame structures', etc. clearly indicate that the basin in which the sediments
were deposited was highly disturbed by movements.
This group of rocks has been
divided into the Bhuban and Boka Bill Sub-Groups, based on the lithological
characters of the rocks. These rocks of the Surma Group are overlain by another
group of sedimentary rocks known as the Tip am Group. Based on their
lithological characters, the rocks of the Tipam sandstone Sub-Group can be
further divided into smaller units known as the Manu Bazar formation at the
bottom and the Champanagar formation on top of it. The Manu Bazar formation
consists of fairly bedded, fine to medium grained sandstone with thin layers of
sandy shale, siltstone and sandy mudstone. The upper part of Tipam known as the
Champanagar formation consists of coarsegrained sandstone with occasional thin
layers of sandy shale and abundant lumps of silicified wood. These rocks were
deposited in near shone condition of deposition. The youngest rock group of
Tripura is known as Dupi Tila Group. The rocks included are sandy clay, clayey
sandstone, all coarse-grained ferruginous sandstone with thin layers of plastic
clays, while silica sand and laterite. Towards the basal part of the Group,
there is a conglomerate bed in which pebbles of clay-stone and siltstone are
embedded in a matrix of sand and clay.
Overlying all the above
rocks, are the unconsolidated sediments like coarse sand, sandy clay, silt, silt
clay, clayey silt and clay, which were deposited by the recent fresh water
channels and in back swamps. In Tripurã the sedimentary rock beds are elongated
in a north-south direction and folded into compressed antidines alternating with
broad very gently depressed syndines. The rock layers are displaced by
sub-vertical faulting predominantly in E-W direction. the axial plane of folding
is chiefly in a north-south direction and produced possibly due to compressional
forces from the East-West direction.
Go to Top
Mineral Resources of Tripura:
The most important mineral potential possibility of Tripura is oil and natural
gas which are being explored by the Oil and Natural Gas Commission. Several gas
seepages were reported by S.N. Sen of the Geological Survey of India in 1956,
near Ampi Bazar, Saikhanbari headwaters of the Channel, Chara stream and about
2 km. W. N. W. of Kiphclapaaa village.
Deposits of white sand with an average silica content above 98 per
cent and suitable for the manufacture at ordinary coloured glasswares occur
along the bank of Bijai nadi stream in Bisramganj with an estimated reserve
1,60,000 tonnes, near old Agartala with an estimated reserve of 50,000 tonnes,
and at Purba and Paschim Champ amura. The sand deposits occur below ito 2.5
thick overburden of soil or clay.
On the recommendations of the
Geological Survey of India, a glass factory was set up at Arundhutinagar near
Agartala with a capacity of 2 tonnes of glassware per day. Sand deposits located
at Agartala may meet the demand of raw material for the production of soda ash
for use in the existing soap factory in Tripura.
White plastic clay suitable for the manufacture of coloured ceramic products
occur at several places near Agartala, Dharmanagar and Bisramganj areas. Small
deposits have been reported from the Teliamura-Ampi Bazar road cutting, and near
Khowai and Jogindernagar.
Grey plastic clay has been
located on the hill-sides near Paschim Champamura with a reserve of 914 tonnes,
in Ranir Bazar with a reserve of 20,000 tonnes, at Sekerkot with an estimated
reserve of 60,800 tonnes. Grey and white plastic clay occur at Tarkarjala
village, Mohanpur, and Latiachhara areas. Most of the clay deposits are
comparatively small in dimension but they are suitable for the manufacture of
ordinary coloured potteries, roofing tiles, etc. Batch samples of some of these
clays have been sent recently to Ceramic factories for Pilot plant tests.
Small occurrences of pyritiferous non-cacing variety of lignite occur in the
rocks on the western flank of Unkoti Kalangshi hill, north of Kumarghat, at
Betaga and Sabrum. The lignite bands are thin and under considerable rock cover
and so cannot be worked economically.
Sporadic occurrences of occasionally fossiliferous siliccou
limestone have been reported from the Sakhan and Jampui ranges. These
occurrences however are of not much economic importance.
In the state there is no hard and durable rock suitable for use as
road metal and for building purpose except the moderately hard calcareous
sandstone concretions. The shale deposits in the Atharamura range can be used
for the manufacture of clay-cement-nodules to be used as road metal for which
there is a great local demand.
The lateritised conglomerate
moorum with quartz pebble is being extensively quarried for road metal. Grey-coloured,
tough calcareous sandstone found in Gagrachara can be used as road metal.
The Geological Survey of India is actively collaborating with the
state Government for the construction of the Manu Earth Dam which is proposed to
be constructed at the upper reaches of the Manu river, for flood control and
irrigation. A gravity type of brick and stone concrete dam with a reservoir at
the upper reaches of the Gomati river has been constructed for the generation of
hydel power from two generators, each having a 5 MW capacity. The Geological
Survey of India was actively associated with the construction of the hydel
project. There is a proposal for construction of a dam in the upper reaches of
the Khowai river to control seasonal floods and improve irrigation.
Go to Top