INTRODUCTION
Significant mineral deposits of iron, nickel, aluminium and clays develop
by residual concentration in different environments with certain specific
evolutions. Among them bauxite and laterite are principle ore deposits.
In 1807 a Surgeon, Francis Buchanan of British East India Company,
firstly introduced word “laterite” (Buchanan, 1807). He observed reddish-brown
colored weathered material in a few places in South India, particularly in wet and
tropical conditions. This material was rich in secondary oxides and hydroxides of
iron and aluminium that he called “laterite”/brick material. Mineralogically,
laterite consists predominantly of mineral assemblages of goethite (Fe2O3. H2O),
boehmite {AlO(OH)}, gibbsite {Al(OH)3}, hematite (Fe2O3), aluminium
hydroxides, kaolinite and quartz. Another significant mineral bauxite that forms
residual deposit was firstly termed by Pierre Berthier in 1821 and was named after
the village Les Baux in southern France, where it was first found, enriched with
alumina.
Laterites and bauxites are produced in tropical soils by weathering, which
enriches iron (laterites) and alumina (bauxites) as well as trace elements such as
nickel, gold, phosphorus, and niobium to ore grade. Laterites and bauxites can be
redeposited into sedimentary sequences, and remain as ores if not transported far
and diluted with other materials. The age of redeposited laterites and bauxites, and
of bauxitic and lateritic paleosols, can be established from the geologic age of
overlying rocks, an approach especially effective in paleosols within sequences of
isotopically datable volcanic rocks (Gregory J. Retallack, 2010).
The Yilgarn Craton is one of the world's principal mineral provinces, with
considerable resources of gold, nickel, bauxite and iron ore, as well as lesser
amounts of a wide range of other commodities. As such, it is a major target for
exploration. However, as most of the Craton has been exposed to sub-aerial
conditions since at least the Late Proterozoic, it has had a long history of
weathering and erosion under a wide variety of climatic conditions, resulting in a
widespread and complex regolith cover. This diverse and extensive regolith poses
considerable difficulties for exploration as well as opportunities in terms of
different sample media and the formation of resources within the regolith itself.
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INTRODUCTION
The development of appropriate geochemical exploration procedures has been the
subject of considerable research by government, university and industry for nearly
50 years (Anand and Butt, 2010).
Although „bauxite‟ is an ore of aluminium, but petrologically, it has been
considered as rock with mineral assemblage of gibbsite, boehmite and diaspore. It
is a member of lateritic family it is characterized by a particular enrichment of
free aluminium-hydroxide. Bauxite is a mixture of mono-aluminium and trialuminium hydrates, with the impurities of titanium, calcium and iron oxides.
Genetically, laterite/bauxite cap parent rocks like basalts, syenites, granites,
arkoses, marl, shale and arkosic sandstones and exposed in the form of regoliths.
Most suitable environment for the formation of laterite/bauxite is freely drained
and strongly leached. Another common loci for bauxite is Karst topography,
where it occurs in caves and solution cavities in limestone. Besides being a
primary material for extraction of aluminium it‟s also used in making refractories,
abrasives, chemicals and cement. It is also used as a fluxing material in steel
melting and in Ferro-alloy industries in place of fluorspar and as absorbent in
refining kerosene.
Most of the Indian bauxite deposits are under the capping of laterite over a
variety of rock types. They are the product of sub aerial weathering and
laterisation of variety of rocks, although the important deposit of Madhya
Pradesh, Chhattisgarh, Maharashtra, Gujarat, Bihar and Karnataka are distributed
on Deccan Trap lava flows. (IBM, 1987) & they classified Indian bauxite in three
major types:
 Continuous: Regular deposits with consistency in grades and thickness;
 Lenticular: Fairly extensive deposits with sharp grade fluctuations; and
 Pocket deposits of inconsistent grades and erratic nature.
Indian bauxite resources are confined to peninsular shield excepting the
occurrences in Jammu in the Extra Peninsular region. In the Peninsular region
about 85% of the total reserve is associated with „high level‟ laterite occurring
along the eastern and western coasts of which nearly 74% of the reserve is
restricted to east coast. About 10% of the total reserves occur amidst inland
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INTRODUCTION
plateaux. The major bauxite deposits of India are generally associated with laterite
occurs as cappings and blankets on the plateaus of high elevation between 700 m
to 2100 m above MSL in parts of Orissa, Andhra Pradesh, Bihar, Madhya
Pradesh, Maharashtra, Karnataka and Tamil Nadu. In contrast, there are coastal
and „low level‟ bauxite deposits found along the coastal tracts of Gujarat,
Karnataka and Kerala (after GSI, 1994).
The important bauxite deposits occur with the „high level‟ laterites in the
following four regions of dissected table lands, viz.;
(1) The Eastern Ghats Orissa and Andhra Pradesh (East Coast Bauxite Belt)
(2) Plateaus bordering Bihar and Madhya Pradesh
(3) Maikala range of Madhya Pradesh (Amarkantak deposits)
(4) The Western Ghats
Besides these smaller and isolated bauxite deposits also occur at :
(i) Shevaroy hills, Kolli hills and Kodaikanal in Nilgiri-Palni hill ranges of
Tamil Nadu
(ii) Seoni, Kaimur and Malwa plateaus and Kaskal –Bailadila range of Madhya
Pradesh
(iii) Vindhyan plateau bordering Uttar Pradesh and Madhya Pradesh
(iv) Kharagpur hills in Mongher district, Bihar
(v) Kumbla in Kerala
(vi) Bauxite in Jammu, J & K State.
1.1 STUDY AREA AND ITS APPROACH
The area of study Mainpat Plateau falls in Surguja district in Chhattisgarh
state, India (Fig. 1.1). It is located in Survey of India toposheet numbers 64 N/1,
N/5 and N/6 lying between longitudes E83°08‟ to 83°25‟ and latitudes N22°41‟ to
22°55‟. The plateau is located about 45 km SSE of Ambikapur, the District
Headquarter of the Surguja. Area is conveniently approachable in all seasons by
well connected by road, from District Headquarter (45 km) and that reaches upto
the top of the plateau. The nearest rail head is Bishrampur (SE Railway) situated
at a distance of 65 km from the study area and nearest air ports is Raipur
(Chhattisgarh) and Ranchi (Jharkhand). Sitapur is the main townships and tehshil
headquarter 28 km from the study area.
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INTRODUCTION
FIGURE -1.1 MAP SHOWING STUDY AREA (MAINPAT PLATEAU) IN
SURGUJA DISTRICT, CHHATTISGARH. (Map not to scale)
1.2 OBJECTIVE OF STUDY
The bauxite deposits are not uncommon in India. Bauxite capping occurs
on many litho-units. Among them Vindhyans and Deccan traps are particularly
underlains the deposits of bauxite. Bauxite reserves in the Chhattisgarh-Madhya
Pradesh state are of the order of 277.76 million tonnes which is approximately
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INTRODUCTION
9.14% of the country‟s total reserves. In Chhattisgarh Bilaspur, Surguja, Raigarh,
Korba, Jashpur, Kanker, Kawardha and Bastar districts are major locations and
the reserve is about 96 million tonnes (CG, DGM-2003-04). Laterite cappings
cover a total area of more than 1500 sq. km. In undivided M.P., following areas
account for more than 80% of the total reserve:
i)
Extension of Bihar plateau region into the districts of Surguja, Raigarh and
Bilaspur.
ii) The plateau region forming the Maikala Hill range (Amarkantak deposit)
in the districts of Shahdol, Bilaspur, Rajnandgaon, Mandla and Balaghat.
Rest of the bauxite reserve occurs in Keskal and Bailadila ranges in Bastar. In
the Mainpat area, Directorate of Geology & Mining (DGM), Chhattisgarh has
established reserves of 33 million tonnes of bauxite. In this plateau bauxite
deposits occur at flat top hills at an elevation 1000 m to 1160 m above MSL in the
form of laterite cappings over Deccan Trap basalt. Bauxite occurs as
discontinuous lenticular and tabular bodies persisting down to a depth of 10 – 12
m from surface. Gibbsite is the main constituent mineral. The bauxite is having
high TiO2 upto 17%. Out of this much of ore reserves of the area are to be
determined in the study area. Available literature reveals that an extensive
research work must be carried out to explore the geology, structure, chemistry and
setup of the formation of bauxite. Thus author took this challenge for his doctoral
research.
1.3 PREVIOUS WORK
Lot of work has been carried out in India and abroad, in an effort to
determine the economic use of bauxite. Fox (1923), Bardossy and Aleva (1990)
did extensive work on bauxites. Velton (1972) carried out a detailed work on
geochemistry and mineralogy of the different bauxite deposits of the world.
A large number of scientific publications are available on Indian laterites
and bauxites. Major bauxite deposits of India were explored and studied mainly
by workers of Geological Survey of India (GSI) among them Roy Choudhary
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INTRODUCTION
(1958), Roy Choudhary et al. (1964 and 1968) are pioneer workers, who Indian
presented a detailed report on Amarkantak bauxite deposits near, Phutkapahar
(Madhya Pradesh) and Ranchi-Lohardaga lateritic bauxite (Bihar).
Bauxite derived from sub aerial weathering of Deccan trap basalt
particularly in Madhya Pradesh, Chhattisgarh, Maharastra and Gujarat have been
attempted by many workers Fox (1923); Sinor (1923); Chatterjee (1951); Murthy
(1952); Roy Choudhary et al. (1964, 1968). However, on the basis of structural,
mineralogical and lithological evidences Ghosh and Dutta (1978) have shown that
Phutkapahar bauxite deposit of Madhya Pradesh was derived from the Gondwana
sandstone. Though the topic is still on debate where many workers considered its
origin from Deccan trap or basalt. Another significant contribution received from
various schools of thoughts about the bauxite originated from Vindhyans of
Central India. Many workers (Swarup, 1973; Murthy et al., 1981; Rao, 1981;
Mehta, 1984; Kalsotra et al., 1986) have described the origin of these deposits by
weathering of Vindhyan shale or sandstone but it was not yet fully proved.
Balasubramaniam (1978) and Sahastrabudhe (1978) carried out a detailed study
on Western Ghat bauxite deposits.
A detailed account on the discovery of Eastern Ghat bauxite and its
resource evolution in the province (Andhra Pradesh and Orissa) has been prepared
by Geological survey of India (1977). These deposits are found on khondalite
(quartz-garnet-sillimanite-gneiss). Khondalite is an acidic rock containing about
80-85% silica in the form of fine grained quartz (Raman, 1976, 1978, 1981; Rao
and Raman, 1979; Raman et al., 1980; Nandi and Slukin, 1983). This discovery
has shifted attention of many geologists from basic to acidic rocks as new source
of bauxite. Eastern Ghat deposits are known for their large reserve, which is
estimated to be higher than 2100 million tones.
The derivation of bauxite from the charnokitic rocks (hypersthene granite)
is also known from the Shevaroy hills in Tamil Nadu. These deposits are fairly
silica rich and overlie the charnokites (Balasubramaniam and Nagarajan, 1978).
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INTRODUCTION
Ray Choudhary (1958), Agrawal et al. (1974), Khan & Pandaya (2000),
Mainkar & Minj (2003), Dhekaware & Chouhan (2005) and Kankane & Sai
(2005) are some of the pioneer workers in this field who worked on the proposed
study area for exploration purposes.
The exploration at Mainpat was carried out by Directorate of Geology and
Mining of Chhattisgarh to categories the ore and its quantity. Agrawal, Vaidya
and Jain (1974) worked on exploration of bauxite of Barima and Khandraja blocks
Mainpat plateau. Khan and Pandaya (2000) reported on prospecting of metal
grade bauxite in Barima area, Mainpat plateau. Mainkar and Minj (2003) worked
on survey and demarcation of bauxite pockets in Jaspur and Surguja District.
Kankane and Sai (2005) worked on rapid survey for demarcation of Bauxite
deposit in Mainpat area. Dhekaware & Chouhan (2005) reported on prospecting
of bauxite in Bijlhwa area Mainpat plateau.
1.4 PHYSIOGRAPHY AND DRAINAGE
The high-lands of Surguja district have peculiar 'pat formations' –
highlands with small tablelands. The Mainpat, Jarang, Jonka, Jamira and the
Lahsun are the major pats of the district. The average height of area is above 600
metres (2,000 ft). Some of peaks are – Mailan 1,226 metres (4,022 ft), Jam 1,166
metres (3,825 ft), Parta Gharsa 1,159 metres (3,802 ft), Kanda Dara 1,149 metres
(3,770 ft), Chutai 1,131 metres (3,711 ft), and Karo 1,105 metres (3,625 ft). There
are number of other peaks. North–west Surguja is hilly in nature and moving
westwards, three distinct steps may be marked out: the first from Shrinagar on the
east to the low-lands of Patna and Khargawan, the second from thence to the
uplands around Sonhat and the third beyond Sonhat to above a height of 1,033
metres (3,389 ft). Central Surguja is a low basin through which the Rihand and it's
tributaries flow.
The Mainpat Plateau exhibits an even flat topped topography. The northern
part of the area is Kamleswarpur (1116m) and western part of the area is Parpatiya
(1158m). The average height of the plateau is 1050m MSL. The major rivers/nala
i.e. Manchari nala, Magarda nala, Ghungata nala and Ghagi nala flowing
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INTRODUCTION
northernly, play an important role in draining the area and showing the Dendritic
drainage pattern. All the nalas flows from the area and are tributaries of Mand and
Barnai Rivers. Detailed geomorphology and drainage has been discussed in the
later chapters.
1.5 FLORA & FAUNA
The Mainpat plateau tops are generally monotonously free from vegetation
but for a few grooves of Sarai occur along with spreaded shrubs. A dense
evergreen shrub 1-3m height with reddish dark, blabrous leaves 12 cm to 15 cm
long, lanccolate margin toothed, petioles 1.25 to 2.550 cm long flowers in short
long axillary‟s spikes and corolla bilabiate is white with purple stamens
abundantly present in bauxite bearing area. The local name is Siktapushi where as
the botanical name of this shrub is “Justicia adhatota Linn.” (Patel et al., 2005).
The rest area covered by brown and whitish soil and being used for cultivation.
Hilly slope terrains are very much covered with different floral species. The
important floral species are Sarai, Sal (Shore arobusta), Teak, Mahua (Madhulika
latifolia), Tendu (Diospyros melanoxylon), Amla (Emblica officivalis), Mango
(Mangiferapyros indica), Jamun (Eugenia jambolana), Saja (Terminalia
tomentosa) and Bel (Aegle marmeto).
The faunal species are Elephant, monkey (Semnipithecus entellus), Indian
wolf (Cannislupus), rabbit and bear (Melasus).
1.6 CLIMATE
According to Trewartha's classification the Surguja falls in AW (AW
denotes Tropical Swanah region) class which is based on temperature and
vegetation. The chief feature of this climate is long dry period. However, on the
basis of vegetation type, the climate of the area is deciduous to Semiarid. During
summer temperature ranges from 150C to 450C while in winter season temperature
fall down to 90C and rainy season starts from middle of June and ends by middle
of September. Average rainfall during the year ranges from 150 cm to 200 cm.
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INTRODUCTION
1.7 SCOPE OF THE STUDY
The present work covers following:

To study geological, geomorphological and tectonic set up of Mainpat
bauxite deposit.

To study the development of laterite profile.

To study configuration of bauxite plateau and morphology of ore body.

Mineralogical variations, transformation of minerals in the laterite profiles.

Detail geochemical study of laterite profile.

Importance and use of bauxite/laterite.

Genetic aspect of these bauxite deposits.
1.8 RELEVANCE OF THE STUDY
Since enough literature is not available to explain the geology, structure
and mineralogenic aspects of Mainpat plateau. Further the Central Indian shear
zone and its significance to mineralisation have not worked out. During the course
of this work it enlarged to prepare a model which explains the genetic aspects of
bauxite in relation to shear zone and hence, the model will be identical for
exploration of similar bauxite deposits in adjoining area.
Geomorphological factors will also be attempted to understand the bauxite
formation. Detailed geochemical studies of laterite profile of this area will provide
data regarding mineralisation in the area. Author is on the opinion that a complete
account of genesis of Bauxite of Mainpat plateau may be prepared after this
research work.
1.9 LIMITATIONS & CONSTRAINTS
Due to unavailability of enough literature on the Mainpat Plateau Bauxite
deposit author put lot of time for field work. Plateau has steep slope and
escarpments and author does not have any training on mountaineering and hence
complete and précised profile of escarpment was not attempted. Since author also
faced lot of problems regarding local language, fooding habits, convince,
remoteness of the study area, etc. Naxallite due to some political causes also
suffered research work at some movements.
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