|Geology Of The Chandrapur District|
The district is occupied by varied rock formations. A glance at the Geological map of the district gives and idea about the varied rock formations. The district is equally rich in Mineral wealth and contributed about 29% of the value of total mineral production of the state. Hence, it felt necessary to describe the geology in a different chapter.
Strata Graphic Sequence in Chandrapur District
|Geologically, Chandrapur districts presents a variety of statigraphic units right from Archaeans to recent alluvium and laterites. The district is gifted with deposits of various minerals like coal, iron. Geological sequence of formations is as follows :|
A brief Description of each of the important geological formations commencing from the most ancient rocks is given below.
The Archaeans comprise gneisses, quartzites, banded haematite quartzites, schists with basic intrusives like pyroxenites, anphibolites etc. The rocks are intruded by several dykes, trending NE-SE, are exposed in the eastern part of Chandrapur district. The dykes are highly shared. The Archaean formations occupy 31.21% of the total area.
The archeans are the oldest rock which are metamorphosed they are comprised rocks called the older schist or unclassified crystalline which are overlain by the metamorphosed sedimentary rocks of Dharwar System and intrusive rocks of the Dharwar such as granites etc. The unclassified crystalline includes Geneisses etc. The sedimentary Dhrwarian rocks are further divided into three groups namely.
Iron Ore series.
Of these Iron Ore series and Sakoli Series are equivalent in age. Iron ore series constitutes the important iron deposits of Chandrapur District. The rocks are Quartzite's , Banded Hematite , Quartzite Schist , Phyllites etc. The rocks and associated iron ore occurs in Bramhapuri and Warora Tahsils of the Chandrapur District. The Dharwar have been intruded on a vary large scale and have been occupied by Granites, Granitoid, Gneisses .
The Vindhyans are represented mainly by flaggy and massive limestone's, shale's and sandstones. The lenticular patches of breccia with angular fragments cemented by alcareous matrix are found at places in limestone's. The limestone's are dolomitic at places. Sandstones and quartzities are hard copact and forms ridges. The limestone's occupy an extensive area in Rajura and Chimur tahsil. The Vindhyans overlie Archaeans basement with well defined unconfirmity. The area occupied by Vindhyans in the district is 23% of total area of district.
a) Cuddpah System The Cuddpah rocks which are mainly crystalline- limestone , According to some geologist the limestone beds associated with sand stones located in Warora are also to be included in the Cuddpah System.
b) Vindhyan System : A vast area in the district is occupied by the limestone , Dolomites Limestone , Purple shells and sand stones.
The area includes Warora , Bramhapuri of Chandrapur District. The limestone and Dolomites are suitable for the cement Manufacturer and as flux in metallurgy respectively.
c) Gondwana system : The older rocks , The Archeans and the Precambrian form the basin for the deposition of rocks of Gondwana System..
1) Lower Gondwana : This include the formation deposited in a glassical period and group of lower Gondwana rocks , includes hard quartzite ,Sandstones , Grits and Conglomerates and is called Mangli bed . The bed is located in Warora Tahsil
Lameta beds : These are infra-Trappe an beds are comprises sandstone often caleareous and charty lime stones and clays . the Lameta beds are located at various places along fringes of deccan trap. They also cover Gondwana rocks as seen in the coalfield near Warora.
Deccan Traps : The Deccan trap lava formation cover the major portion of the state , but occupies vary small part of the District . At the close of Mesozoic Era , major portion of the state was covered by a sub-aerial Deccan Trap lava close which spread in the form of nearly horizontal beds . The earlier flows than filling up irregularities of the than existent relief . The thickness is vary less and is about 40 Meters. Near Bothali village in Warora Tahsil.
The trap commonly shows following types
a) The compact and Harder flows often characterized by vertical Prismatic or Columnar jointing .
b) The amygdaloidal softer variants varieties usually showing in filling of Calcite etc.
c) The red bole bed representing perhaps alter ferruginous flows .
The lower Gondwanas are represented by Talchirs, Barakars and Kamthis series. The lower Gondwanas are exposed in Warora, Chandrapur, Ballarpur and Rajura Tahsil. The thickness of lower Gondwanas very laterally.
The Talchir series consists of boulder beds which are conglomeratic and pebbly in nature at the base. The olive green coloured shales and greenish yellow sandstones are the other rock types. These sandstones are rocks are exposed over a wide area stretching from west up to the boundary of Maharashtra and Andhra Pradesh. The Typical Talchir olive greenshales are exposed at village Tadali on Warora- Chandrapur road. In Wirur area, the base of Talchir formation is defined by tillites with predominance of boulders of sandstones. The tillites are succeeded by cross bedded sandstones and the Talchir` sequence is much alternated here. The total area covered by Talchir in the district is 750 sq. Kms. i.e. 7 % of the total area.
The Barakars are represented by white coloured, fine to medium grained sandstone, shales, clays and coal seams. The thickness of Barakars increases towards east and thickness in general ranges between 30-250 m. But the exposures of these rocks are scarcely seen and mostly concealed below the Kamthi sandstones, The area covered by Barakars in the district is 1% of the total area.
The Kamthi series comprises sandstones, silstones, variecated clays and shales. They are exposed over a wide area in Chandrapur district. In the eastern part of the district, the maximum thickness of 500 m can be expected. These sandstones are yellowish and white in colour, fine to coarse grained in and at places ferruginous in nature. These sandstones are found to be siliceous or fossiliferous at some places in the district. The area occupied by these rocks in the district is 19% of the total area.
The upper Gondwana formation is represented by Maleri series. The rock types are sandstones and shales. The sandstones are fine grained whitish coloured and calcareous un nature. The shales are of red colour and are found in a small patches in the south-eastern part of Chandrapur district. The areal extent of these rocks are very small.
Laterites are commonly seen as over Deccan traps, Kamthi sandstones and gneisses. It is generally reddish brown in colour. It is hard and thickness of which varies from a few cm. to 8 m.
In the district, Alluvium is mostly river-alluvium and comprises sand, silt and clays. It is generally found along the banks of nalas and rivers. The thickness varies from 8 to 35 m as observed along the Wardha, the Erai and the Wainganga river courses. Italso contains gravel along with sand, silt, clays at places. In Brahmapuri tahsil, patches of alluvium (about 100 sq.km.) are observed on the western bank of the Wainganga river near Brahmapuri. Similar patches of alluvium are also found of Chimur and warora along the Erai and the Andhari nadi and also around Chandrapur along the course of the Wardha reiver. The maximum thickness of alluvium is observed in Brahmapuri area.
Laterites and Alluvium together occupy together an area of 820 km. i.e. 8% of the tota area of the distrit.
The regur or black cotton soil is derived from Deccan traps commonly known as “Kali”. Red soil is most common in the area covered by gneisses and other crystalline rocks. There is a thin veneer of soil (8 to 15 m) over lying the Gondwana formation in the north-western part of the district.
Structure and Subsurface Geology
On the baisi of availble subsurface data collected during exploration of coal deposits and coal mining it is found that of all the formations in the district, the Gondwanas are structurally highly distributed on a large scale.
On a regional scale Gondwana formations can be classified as broad anticlinal structure plugging towards NNW. The Sasti, Ballarshah, Lalpeth, Mahakali, Reyatwari and Durgapur coal fields in the district are located in the eastern limb of an anticline while Ghugus, Magri, Telwase and Chinchola coal fields are located in western limb.
Chanda-Wardha Gondwana basin occuring in the district is essentially a broad graben structure. Geographical survey in Chanda-Wardha valley also shows that whole area is associated with a negative Bougar Anomaly ranging from 20 to 72 mgd. Which further confirms the graben configuration. Structurally Wardha valley basin represents by a number of faults resulting in a number of different coal fields around Chardrapur. The structural analysis of the Wardha valley shows that Gondwana formations are aligned in three sub-parallel troughs. The westernmost i.e. the Pranahita trough contains major coal resources in the area.
In Durgapur area, five major faults trending E-W have been detected with a general downshrow towards south varying from 50 ti 70 m. The entire area between Durgapur and Lalpeth Colliery lies between two major fualts with regional trend of NW-SE The same NW-SE tredning fault system are dominant between Isapur block and Durgapur in the north. This has resulted in the epetition of coal seams.
The other formation like Vindhyan, Lametas, Deccan Traps are not showing any major strucctural disturbances within the formation. The structural features noticed in these rockas
are fractures, joints and weathering. The gneisses, Vindhyan sandstones and massive basalts are weathered, jointed and fractured at a number of places. The degree of weathering os varying from moderate to hogh. The thicknesss of weathered zones normally ranges between 3 and 5 m. in gneisses and Deccan trap while it is comparatively less in Vindhyans. The depth of jointed zones also varies from place to place. The unconformity is observed between Vindhyans and Gondwanas and also between Gondwanas and Deccan Traps.
The Archaeans which are exposed in eastern part of the district are separated from other sedimentary formations by N-S trending boundary fault. The geophysical data shows that the boundary fault appears to be normal fault having a throw of about 500 to 700m.
The Archaeans basement and overlying Vindhyans are separated by district incomformity. The Kamthis and Barakars are also separated by angular infomformity and because of these the amount of dips of the two formations show discordance. The Kamthis are having low dips as compared to Barakars.
The major portion of the Archaeans are subjected to tectonic disturbances resoulting in a number of major and minor lineaments in the area. The acid intrusives such as pegmatites and brecciated qualtzites and basic dikes are also presents in the area.
On the basis of the study of aerial photographs of Chandrapur district, lineaments are fracture planes in the rock formations which are to be confirmed by field checks.
The total area of the district has been divided into eleven geomorphic units. The Structural Ridges, Structural Hills, Highly and Moderately Dissected Plateau over the Deccan Traps are grouped into geomorphological units of structural origin. The pediments/pediplains and Denudational hills are grouped into geomorphological units of denudational origin, whereas, the younger and older alluvium form the units of fluvial origin.
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