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DISTRICT SURVEY REPORT OF NAMAKKAL DISTRICT
DISTRICT SURVEY REPORT
OF NAMAKKAL DISTRICT
PREFACE
In Compliance to the Notification Issued by the Ministry of Environment, Forest
and Climate change Dated 15.01.2016, the preparation of District survey report
of minor minerals is in accordance appendix 10 of the notification. It is also
mentioned here that the procedure of preparation of District Survey Report is as
per notification guidelines. Every effort have been made to cover mining
locations, areas & overview of Mining activity in the district with all its relevant
features pertaining to geology & mineral wealth in replenishable and non-
replenishable areas. This report will be a model and guiding document which is a
compendium of available mineral resources, geographical set up, environmental
and ecological set up of the District and is based on data of various departments,
published reports and websites. The data may vary due to flood, heavy rains and
other natural cliamities. Therefore, it is recommended that Sub Divisional Level
Committee may take into consideration all its relevant aspects / data while
scrutinizing and recommending the application for EC to the concerned
Authority.
SURVEY REPORT
OF
NAMAKKAL DISTRICT
As per Gazette notification of 15th January 2016 of Ministry of Environment,
Forest and Climate Change a Survey shall be carried out by the District
Environment Impact Assessment Authority (DEIAA) with assistance of
irrigation department, Drainage department, Forest department, Mining
department and Revenue department in the district for preparation of District
Survey Report as per the sustainable Miner mineral mining guidelines to ensure
identification of areas of aggradations or deposition where mining can be
allowed; and identification of areas of erosion and proximity to infrastructural
structures and installations where mining should be prohibited and calculation
of annual rate of replenishment and allowing time for replenishment after
mining in that area.
Every effort have been made to cover mining locations, areas & overview of
Mining activity in the district with all its relevant features pertaining to geology
& mineral wealth in replenish-able and non-replenish-able of particular areas.
The mineral potential is calculated based on field investigation & geology of the
catchment area. Also as per the site conditions and locations, depth of minable
mineral is defined. The area for removal of the mineral in a particular area is
decided depending on geo-morphology & other factors, it can be 10% to 40% of
the area. Other constituents like clay soil and silt are excluded as waste while
calculating the mineral potential of particular mining area. This District Survey
Report shall form the basis for application for environment clearance,
preparation of reports and appraisal of projects. The report shall be updated once
every five years.
1.0 INDRODUCTION:
Namakkal district is bounded by Salem district on the north; on the east by Attur
taluk of Salem district, Perambalur and Tiruchirapalli District's; by Karur District on
the south and on the west by Erode district.(Namakkal District profile, SouthIndia
Online) Namakkal District comes under the North Western Agro climatic zone of Tamil
Nadu. It is situated in the dividing portion of two watersheds between Cauvery and the
Vellar System with the Taluks of Attur, Rasipuram and Namakkal on the East and
Salem, Omalur and Mettur on the West. Tiruchengode taluk alone is placed under
Western Agroclimatic zone Namakkal District, Govt of Tamil Nadu Besides the above
two zones, Kolli and a few isolated hills and ridges are scattered over Namakkal,
Rasipuram and Tiruchengode and along with the valleys and rolling hills, make up the
characteristic topography of the district.
Fig.No.1: NAMAKKAL DISTRICT AND TALUK MAP
The Namakkal District lies in the interior of Tamilnadu between the North
Latitudes 11° 00' 00" to 11° 36' 10" and East Longitudes 77° 40' 00" to 78° 30' 00". The
total geographical area of the District is 3404.3 sq. km. The district has been is divided
into four taluks namely, Namakkal, Thiruchengode, Paramathi and Rasipuram and
fifteen administrative blocks. The location of the study area is shown in the Figure 1.
2.0 PHYSICAL FEATURES & GEOGRAPHICAL AREA:
a) Brief detail of Namakkal District
S.NO ITEMS STATISTICS
i)
GENERAL INFERMATION
a) Geographical area(S.q.km) 3404.3 sq.km
b) Administrative divisions as on 31.03.2007
c) Number of Taluk 05
d) Number of Block 15
e) Number of villages 454
f) Number of Panchayats 331
ii) Population
(as on 2011Censes)
Total population
Total- 1495661
Male- 760409
Female-735252
iii) Average annual rainfall (mm) 650 - 900
Geomorphology
I. Major physiographic
Units
Upland plateau region with hill
ranges and undulating plain.
ii. Major Drainages Cauvery, Tirumanimutar
iv)
Landuse (Sq.km)
a) Forest area
b) Net area sown
c) Cultivable waste
439 Sq.km
1765 Sq.km
48 Sq.km
v) Major soil types Red soil, Black soil, Brown soil,
Alluvial soil & mixed soil.
vi)
Area under principal crops
a) Paddy 18832Ha-9.20%
b) Groundnut 47639Ha-23.0%
c) Sugarcane 13278Ha-6.4%
d) Oil seeds 20073Ha-12%
e) Fodder 38010Ha-18.5%
vii)
Irrigation by different
sources
Number of area irrigated (Ha)
Number
Area irrigated
(Ha)
i) dug wells 75961 40879
ii) Tube wells /Bore wells 5144 21730
iii) Tanks/ ponds 259 799
iv) Canals 3 4915
v) Other sources --- 5995
vi) Net irrigated area 74318Ha
vii) Cross irrigated area 88146 Ha
viii) Predominant Geological
formations
Alluvium, Colluvium, Laterite,
Granite, Dolerite, Quartzite,
Charnockite and Granite
Gneiss.
ix)
Hydrogeology
i) Major water bearing
formations
Alluvium, Colluvium,
weathered &fractured Granite
Gneiss, Charnockite.
ii)Pre-monsoon depth to water
level 1.20 – 14.33m bgl.
iii) Post-monsoon depth to water
level 0.86 – 16.60m bgl.
x) Long term water level trend in 10
years(2006-16)in m/yr
Annual
Rise
(m/year) Fall (m/year)
Min:0.0335
Max:0.6159
Min:0.0186
Max:0.9738
xi)
Ground water exploration by CGWB (As on 31-03-2016)
a) Number of exploratory wells
drilled 14
b) Number of observation wells
drilled 07
c) Number of Piezometers drilled
under Hp 13
d) Depth of range(m) 76.61 – 300.00
e) Discharge(lps) 0.50 – 15.26
f) Specific capacity ( Lpm/m ) 4.491 – 57.85
g) Transmissivity (m2/day) 2 - 45
xii)
Ground water quality
i) Presence of chemical
constituents more than
permissible limit
TH as Ca CO3, NO3, F
ii) Type of water NaCl & mixed type
xiii)
Dynamic ground water
resources
a) Annual replenishable ground
water resources 493.51
b) Total Annual ground water
draft for all purposes. 514.31
c) Projected demand for
domestic and industrial uses
up to 2025
24.47
d) Stage of ground water
development 106%
EFFORTS OF ARTIFICIAL RECHARGE & RAINWATER
HARVESTING
I. Project completed by
CGWB Number of
structures Amount
spent
Construction of Subsurface
Dyke at Kunavelampatti under
central sectore scheme
16. MAJOR GROUND WATER
PROBLEMS AND ISSUS
1) High level of ground
water development.
2) Declining of ground water
level and drying of
shallow wells.
3) Inclidence of fluoride in
ground water.
4) Local pollution of surface
and ground water by
industrial units.
b) Administrative Details
Namakkal district is divided into 5 taluks. The taluks are further
divided into 15 blocks, which further divided into 39 villages.
Adiministrative set-up of Namakkal District
S.
No
Taluk Area
(sq.km)
No.of
Villages
Block No.of
Villages
1 Namakkal 1244.6 117 Namakkal 23
Puduchatram 30
Sendamangalam 17
Erumaipatti 25
Kolli Hills 7
Mohanur 15
2 Paramathi
velur
523.06 60 Paramathi 23
Mohanur 11
Kabilarmalai 26
3 Rasipuram 817.48 102 Rasipuram 25
Vennandur 30
Namagiripet 38
Kolli Hills 9
4 Tiruchengode 844.16 112 Tiruchengode 38
Mallasamudram 27
Elachipalayam 29
Pallipalayam 18
Total 3429.3 391 391
c) Drainage
Cauvery River, which is perennial in nature, flows along the western
and southern boundaries of the district. Tirumanimuttar river, which is
the the most important tributary of Cauvery in the district and traverses
the district before its confluence with Cauvery at Nanjai Edayar village of
Paramathi taluk. A samall area in the northern part, which is drained
mainly by vasista and Sweta Nadi Rivers, which are tributation of vellar
River.
d) Irrigation Practices
The nine – fold land use classification for the district is given below
S.No Classification Area
1 Forests 43909
2 Barren & Uncultivable Lands 24743
3 Land put to non agriculture uses 38302
4 Cultivable Waste 4781
5 Permanent pastures & other
grazing lands
6684
6 Groves not included in the area
sown
3854
7 Current Fallows 28375
8 Other Fallow Lands 9143
9 Net Area sown 176544
Total 336335
The data available indicate that an area of about 74318Ha is under
irrigated agriculture. Dug wells are the major source of water for
irrigation in the district, accounting for about 55% of the total area
irrigated in the district. Canals and tanks account for about 8% each.
The block wise and source wise net area irrigated in Ha is given below
S.
No
Block
Net area irrigated by
Total
Net
Area
irrigated
Canals Tanks Tube
wells
Ordinary
wells
Other
sources
1 Elachipalayam 0.00 0.00 2410 1506 0.00 3916
2 Erumaipatti 0.00 1268 1120 5622 218 8228
3 Kabilarmalai 3149 0.00 0.00 3507 3050 9706
4 Kolli hills 0.00 0.00 6.00 0.00 788 794
5 Mallasamudram 0.00 2724 142 1567 0.00 4433
6 Mohanur 412 206 757 5318 8.00 6701
7 Namagiripet 0.00 0.00 291 4893 20.00 5204
8 Namakkal 0.00 0.00 96 1667 0.00 1763
9 Pallipalayam 1209 0.00 296 2383 986 4874
10 Paramathi Velur 337 0.00 95 5983 0.00 6415
11 Puduchatram 0.00 0.00 258 4059 0.00 4317
12 Rasipuram 0.00 0.00 496 1711 0.00 2207
13 Sendamangalam 0.00 0.00 130 5413 1057 6600
14 Thiruchengode 1040 0.00 406 4564 0.00 6010
15 Vennandur 0.00 0.00 242 2908 0.00 3150
Total 6147 4198 6745 51101 6127 74318
e) RAINFALLS AND CLIMATE
The district receives the rain under the influence of both southwest
and northeast monsoon. The northeast monosoon chiefly contributes to the
rainfall in the district. Most of the precipitation occurs in the form of
cyclonic storms caused due to the depressions in Bay of Bengal. The
southwest monosoon rainfall is highly erratic and summer rains are
negligible.
Rainfall data from six stations over the period 1901 – 2000 were
utilized and a perusal of the analysis shows that the normal annual
rainfall over the district varies from about 640 mm to 880 mm. It is the
minimum around paramathi in the southwestern part of the district. It
gradually increases towards north, northeast and east and attains a
maximum around Rasipuram in the northern part.
The district enjoys a tropical climate. The weather is pleasant
during the period from Novermber to January. Mornings are more humid
than the afternoons, with the humidity exceeding 78% on an average. In
the rest of the year the afternoons are driver, the summer afternoons
being the driest.
The hot weather beings early in March, the highest temperature
being felt in April and May. Weather cools down progressively from about
the middle of June and by December; the mean daily maximum
temperature drops to 30.20 C, while the mean daily minimum drops to
19.20C and 19.60C in January in Salem and Mattur Dam respectively.
Though the maximum temperatures in February are about the same as in
July, the nights are much cooler in February. Being an interior district,
the diurnal range of temperature is large, particularly in the dry and hot
seasons. In February-March the mean diurnal range of temperature is as
high as 13.70C while in October – November it is only about 90C.
3.0 GEOMORPHYLOGY AND SOIL TYPES
a) Geomorphology
Namakkal district forms part of the upland plateau region of Tamil
Nadu with manly hill ranges, hillocks and undulating terrain with a
gentle slope towards east.
The prominent geomorphic units identified in the district through
interpretation of satellite imagery are
i) Structural hills,
ii) Bazada zone,
iii) Valley fill,
iv) Pediments
v) Shallow pediments
vi) Deep Pediments.
A number of hill ranges are located in the eastern in the eastern and
northeastern parts of the district, whereas the southern, western and
northern parts of the district are plain to undulating, dotted with a few
isolated hillocks. The important hill ranges in the district are Kollimalai
hills, Bodamalai hills, Naraikinaru hills and pachamalai hills. The
highest peak in the district is the Kollimalai hill with an elevation of
1293m above MSL. Other important peaks are kedda malai and Melur
hill in the Bodamalai hill range.
b) Soils
The soils of Namakkal district can be broadly classified into 5 major
soils type viz., Red soil, Black soil, Brown soil, Alluvial and Mixed soil.
Major part of the district covered by Red soil. Block soils are mostly seen
in Namakkal taluk. Beown soil occupies only a small portion of
Tiruchengode taluk and the alluvial soil is seen along the river courses in
Namakkal, paramathi and Tiruchengode taluks. Mixed soil is the second
major second major soil type occurring all the taluks of the district.
c) GROUND WATER SCENARIO:
i) Hydrogrology
Namakkal district is underlain entirely by Archaean Crystalline
with Recent alluvial deposits occurring along the river courses and
Colluvium at the foot hills. The important aquifer systems in the district
are constituted by weathered & fractured crystalline rocks and Colluvial
deposits.
The porous formations in the district are represented by alluvium
and colluviums. The alluvial deposits are confined to the major river
courses only. Ground water occurs under phreatic conditions. The
maximum saturated thickness of these aquifers is up to 5 m depending
upon the northern parts of the near by hill ranges comprising sands and
gravels. The maximum saturated thickness of the aquifers is up to 20 m
depending upon the topographic conditions. Ground water occurs under
phreatic conditions.
The hard consolidated crystalline rocks of Archean age represent
weathered and fractured formations of Granite gneiss, Granite,
Charnokite and other associated rocks. Ground water occurs under
phreatic conditions in the weathered mantle and under semi- confined
conditions in the fractured zones. The thickness of weathered zone in the
district while range from < 1m to 30m. It is within the depth of 20 m in
major part of the district, they are more than 20 m. The depth of the dug
wells ranged from 7 to 45m bgl. The yield of the open wells range from <
50 to 200 m3/ day in weathered crystalline rocks and up to 400 m3/ day in
recent alluvial formations along major drainage courses.
The yield of bore wells drilled down to a depth of 40 100 m, by
various state agencies manily for domestic purposes ranged from 90 to
360 liters per hour. The yield of successful bore wells drilled down to a
depth of 300 m bgl during the ground water exploration programme of
Central Ground Water Board range from < 1 to 15 Ips. The aquifer and
well parameters of the wells show wide variation.
The depth to water level in the district varied between 1.20 – 14.33 m
bgl during pre monsoon depth to water level and varied between 0.86 –
16.60 m bgl during post monsoon depth to water level.
The seasonal fluctuation shows a rise in water level, which ranges
from 0.03 to 3.51 m bgl. The piezometric head varied between 1.35 to 9.40
m bgl during pre monsoon and G.l to 13.00 m bgl during post monsoon.
Aquifer parameters
Aquifer Parameters Weathered
Residuum
Fractured Aquifer
Transmissivity( m2/day) <1 - 100 2-106
Storativity - 9.6 X 10-5 – 4.3 X 10-2
Specific yield 0.015 -
ii) Ground water Resources
The ground water resources have been computed jointly by Central
Ground Water Board and State Ground & Surface Water Resources and
Developmetn Centre. The salient feature of the computations is furnished
below. The computation of ground water resources available in the district
has been done using Gec 1997 methodology.
iii) Ground water Quality
Ground water in phreatic aquifers in Namakkal district is in general
colorless, odorless and predominantly alkaline in nature. The specific
electrical conductance of ground water in phreatic zone during May 2006
was in the range of 1300 to 7080 in the district. It is between 2000 and
4000 µS/cm at 250 C in the major part of the district.
It is observed that only in selected places of the distrct, the ground
water is suitable for drinking and domestic uses in respect of all the
constituents. The total hardness as CaCO3 as well as nitrate is observed
to be in excess of permissible limits in about 66 and 86 percent of samples
analysed. Fluoride in excess of the drinking water limit of sulphates was
in excess of the drinking water limit of 400 mg/l.
The incidence of high total hardness and fluoride is attributed to the
composition of lithounits constituting the aquifers in the district, whereas
the nitrate pollution is most likely due to the use of fertilizers and other
improper waste disposal. Excess of fluoride is observed in place such as
Venandur, udaiyarpalayam, Talamabadi, V.G.patti and Mohanur.
With regard to irrigation suitability based on specific electrical
conductance and sodium Absorption Ratio it is observed that ground water
in the phreatic zone may cause high salinity hazard and medium to high
alkali hazard when part of the district while ground water for irrigation.
iv) Status of Ground water development:
The estimation of groundwater resources for the district has shown
that 8 blocks are over exploited and 2 blocks are under “critical” category.
Tamil Nadu Water supply and Drainage ( TWAD) Board is the
Government agency responsible for providing drinking water supplies to
the urban and rural populace in the distric. The water requirements of
the habitations are met with either through surface water sources or
through surface water sources or through various Mini Water supply
schemes or integrated water resources. The status of urban and rural
water supply in the district as in March is furnished below
Total Number of Rural Habitants : 2875
Not Covered : 395 (0-9 LPCD)
Partly Covered : 1422 (10-39 LPCD)
Fully Covered : 1058 (>40 LPCD)
The habitants of 5 Municipalities of the district are provided with 70 – 90
LPCD water and the habitants 19 special Panchayats are provided with
20 – 70 LPCD water. Dug wells have traditionally been the most common
ground water abstraction structures used for irrigation in the district,
with yields ranging from <50 to 200 m3/day in weathered crystalline rocks
and up to 400 m3/day alluvial formations along major drainage courses.
4.0 GROUND WATER MANAGEMENT STRATEGY:
i) Groundwater Development:
In view of the comparatively high level of ground water development
in the major part of the district and the quality problems dug to geoogenic
and anthropogenic factors, it is necessary ground water resources in the
district.
The development of ground water for irrigation in the district is
mainly through dug wells tapping the weathered residuum. The yields of
dug wells are improved at favourable locations by construction of
extension bores, which are 40 to 70m deep. Bore wells have also become
popular as the source for irrigation in the district in recent years. Dug
wells with extension bores wherever necessary is ideal for hard rock areas
whereas large diameter dug wells with radials is suitable for alluvial
areas. The map showing the development prospects for the district.
ii) Water Conservation and Artificial Artificial Recharge
CGWB had prepared a master plan to augment groundwater potential
by saturating the shallow aquifer taking into consideration the available
unsaturated space during post monsoon and available uncommitted
surplus run off. Subsequently, computations have been made for Drought
prone Area Programme (DPAP) for over exploited and critical blocks in the
districts warranting immediate attention. Institute of Remote Sensing,
Anna University had prepared block wise maps demarcating potential
zones for artificial recharge for the state of Tamil Nadu. Subsequently,
state Government agencies have constructed artificial recharge structures
with their own fund or with fund from central Government, dovetailing
various government programmes.
Ministry of Water Resoures, Government of India has initiated Dug
well Recharge scheme in the state. The scheme is being implemented by
the Nodal Department with the technical guidance of CGWB. The subsidy
for small and marginal farmers and 2000/- for the other farmers is credited
to the beneficiaries bank account through NABARD. The scheme after
implementation will prove to be beneficinal to the irrigation sector. The
available uncommitted surplus run off has to be recomputed, taking into
consideration the quantum of recharge affected through existing irrigation
dug wells also. The existing structures and uncommitted surplus flow
should be considered for further planning of artificial recharage
programme.
On the basis of experimental studies, it has been found that desilting
of existing tanks followed by percolation pond with recharge wells,
recharge shafts are economical.
There is considerable scope for implementation of roof – top
rainwater harvesting in the district. Recharge pits / shafts / trenches of
suitable design are ideal structures for rainwater harvesting in such areas.
Central Ground Water Board is also providing free technical guidance for
implementation of rooftop rainwater harvesting schemes.
iii) GROUNDWATER RELATED ISSUES & PROBLEMS
The ground water development in the district, in general, is high
when compared to many other districts in the state. 10 out of 15 blocks in
the district have district have been categorized as either overexploited or
critical. The trend analyes of historical ground water level data also
indicate a long-term fall in a major part of the district.
Based on the factors mentioned, it is inferred that a major part of
the district could be considered vulnerable to various environmental
impacts of the district could be considered vulnerable to various
environmental impacts of water level depletion such as declining ground
water levels, drying up of shallow wells and decrease in yield of bore wells.
Incidence of fluriod in ground water in excess of permissible limits for
drinking has been reported from parts of the district, especially from the
fracture zone. Tamil Nadu Water supply and Drainage Board have
provided a number of villages in the district with fluriod – free drinking
water supplies. Excessive use of fertilizers and pesticides in agriculture
has also reportedly in localized enrichment of nitrate and other harmful
chemical in the ground water, especially in the phreatic zone.
Pollution of ground water due to Sago industry is also one of the
issues in the district. The effluents from which have caused local pollution
of surface and ground water resources.
iv) AREA NOTIFIED BY CGWA/SGWA
Central Ground Water Authority has not notified any area in the
district.Government of Tamil Nadu vide G.O.No 53 has resitricted
groundwater development for irrigation in the over exploited blocks of
Tamil Nadu. The over exploited blocks in this district are as follow.
1. Erumapetti 6. Rasipuram
2. Namagiripettai 7. Sendamangalam
3. Namakkal 8. Vennandur
4. Pallipalayam
5. Puduchatram
5.0 GEOLOGY
Namakkal district is mostly underlain by the Archaean crystalline
and metamorphic complex. The geology of the district is complicated due to
recurring tectonic and magmatic activities occurred during pre Cambrian
period. The famous sithampoondi complex which is known for its complex
geology is situated in this district. Gneisses are the oldest rocks in four
taluk of the district. It is present widely in plains. The gneisses are highly
weathered upto 30 m at some places. The charnockites are coarse grained
and their colour is bluish dark to grey. They are massive and the second
largest rock type present in the district. They are massive and less
weathered than the gneisses. They exhibit 2 to 3 distanct set of joints and
most of them are vertical with steep dips. Iron ore deposits associated with
quartz feldspathic gneiss and garnetiferous quartz gneisses are present in
some areas. These rocks are highly folded and jointed and less weathered.
Calcite quartzites and crystalline limestone are exposed in patches
in north and central parts of the district. The thickness of these bands to
few metres to ten metres and the length extends to few kilometers.
Massive and poorly jointed anorthosites bearing rocks are also found. They
are associated with wide range of Chromite, Pyroxenite, Anthophyllite,
Diopside, etc. There are number of basic intrusive of Dolerite dykes are
found in some parts of the district. They are massive and jointed poorly.
Thin veneer of alluvium is found along the course of the Cauvery and
Thirumanimuthar. Howere, alluvium of river Thirumanimuthar and river
Cauvery. Several faults and shears are occurring mostly with north east-
south west trend. They are expected to influence the course of
groundwater movement, its storage and developmental potentials in the
district.
Dunities and Peridotites
The rocks appear in the area of sithampoondi Villages of Namakkal,
which are known. Charnockites occur as lenses within the ultramafic and
hence it can be said that these intrusive are of post chanockite period.
Dunite have undergone enormorus mineralogical chalcedony etc.
magnesite occurs in the forms of the gneisses and are highly weathered
and talc occurs at many places as economic deposits. The Talcschist,
Flespathic- schist and Hornblede-schist formed by deformation of basic
igneous rocks are also seen in a few places in study area.
Pyroxenites
Pyroxenites occur in rest and south of the sithampoondi, and also
massively and poorly jointed in the Nagarmalai. Pyroxenites patches occur
in one most of the place in the chalk hills. The contact between the
pyroxenites and peridotites in not clearly identified.
Dolerite Dykes and other Intrusives
There are a number of basis dykes intruding in the country rocks.
They are massive and running in NE-SW to NNE-SSW direction in
general, parallel to the foliation direction and a few kilometers in length.
Their contact with the country rock is sheared at many places.
Granites and Syenites
The granite and syenites are massive and poorly jointed. There are
two pegmatite intrusions in the sithampoondi noticed and locally called as
“WHITE ELEPHANT ROCK”.
Laterites
The physical weathering and leaching in the flat-topped hillocks of
have rise to Laterites rich is alumina. There are also a few pockets of
bauxite in these hills. The weathering is 10 to 15m deep.
Alluvium and Talus
There is a poor deposite of alluvium along the course of the Cauvery
as it runs mostly on high land and rocky floor. So is the case with
Tirumanimuttar River which also flows on rocky floor.
Anorthosite
Sithampoondi village Tiruchengode blocks area cromite mineral, and
corumdum, olivine dunite in the rock.
Limestone
The crystalline variety of Limestone is manily available in this
district in parts of Namakkal, Tiruchengode and paramthivelur Taluks. 1.
High Limestone 2. Medium grade or soapstone is composed of Talc and
stealite, which is a hydrated silicate of magnesium. It occurs in parts of
Rasipuram taluk.
Rocks and Minerals
The Black Granite (dolerite) is a ferromagnesian mineral bearing
rock; due to the presence of high specific gravity mineral in the rock type
it has heavy weight and dark colours. In this District, only two leases
were granted for Black Granite both leases are in currency, but not in
operation. The Multicoloured Granite rocks are manily available in
paramathivelur, Kabilarmalai areas. It is a light coloured, less weight
rock 6 leases were granted to extract colour Granite. In this District, out
of 6 leases, two leases are mainly functioning at present.
Gneisses
The gneisses are perhaps the oldest rocks in the namakkal occurring
widely in the plains. The general direction of foliation varies from E-W to
ENE-SWW with a high magnitude dip towards north or south east.
Segregated quartz- feldspathic and mafic layers give rise to banded
structure at some places. The Gneisses by several Ultramafic and basic
rocks parallel to the direction of foliation of the gneisses.
Charnockites
The charnockites, Namakkal are thalamalai coarse-grained and
bluish dark to grey in colour, have the second largest occupying area.
They are exposed in the Sheveroys hills. Some of the Charnockites are
garnetiferous and are massive and less weathered than the gneisses.
They show two to three distinctsets of joints most of which are vertical
with steep dips.
Magnetite – Quartzites
These rocks occur in the Valayapattilai Magnetite – quartzites are
major non-ore deposits and are associated with quartzo-felspathic
gneisses in the area. These rocks are highly and jointed.
Bauxite (Aluminum ore)
Bauxite is a hydroxide of aluminium. It occurs mainly in the kolli
hills. The total reserves of Bauxite in Kolli hills have been estimated to be
around 2.75 million tones. This ineral is available in a huge quantity on
the Kolli hills.
Magnasite
Magnesium rich corbonate rocks are otherwise called as Magnasite.
Inferior variety of Magnasite Mineral is a available in Seerappalli, and
Sithampoondi Villages of paramathy velur Taluks and mangalamedu
village in Rasipuram Taluk.
Quartz and Feldspar
Silica rich quartz and pottcesium Alumina and silica rich Feldspar
minerals are available in this District in parts of Namakkal,
Thiruchengode and Paramthy – velur Taluks. These types of minerals are
mainly formed in the pegmatite band which is occurring in several
villages of the above mentioned Taluks. At present, 25 mining leases for
these minerals are in currency.
Rough stone: The “Charnockite” and Granite Biotite gneiss rocks types
of this District is mainly used for Roughstone.
Gravel: It is a mineral, admixed with soil (hard soil produced by
cerushing of loose rocks) and fragments of weathered (easily broken) rock
pieces. It is mainly used for Road making and filling purpose. It is mainly
available in all parts of the District.
Brick Earth: This is reddish in colour, loose in nature it does not contain
fragment of rock pieces etc pure reddish soil is mainly used for the
purpose of Manufacturing of Bricks. It is mainly available in all parts the
District.
River Sand: The River sand is available only in River bed. In this
District, in Cauvery River several strectch contains sand heaps. Joints in
the area, with has experienced at least three district phase of the tectonic
movement.
Fold: The Salem – Namakkal fold Thrust Belt consists of number of low-
angle south-dipping thrust sheets demarcated by ductile shear zones. In
many places they have been steepened by refolding, along the
L.kanavaipatti shear zone south of Namakkal. Mylonites are prominently
developed in the foothills of Godumalai hill. These show kinematic
indicators, mainly S-C fabrics, rotated porphyroclasts and intragranular
faults, suggesting thrust-related tectonics with N to NE verging shear.
However, in many instances the mylonites have undergone static
recrystallisation. The mylonitisation is post-kinematic with granulite
facies metamorphism.
Peak granulite metamorphism has occurred during the F1 stage of
folding, which is characterised by isoclinals folds developed in bedding,
palnes, and represendted by BMQ layers in quartzofeldspatic gneisses.
The F1 folds has produced penetrative gnessic fabrics and are coaxially
refolded by open to tight upright F2 folds producing type 3 interference
patterns. The F2 folds are accompanied by shear bands along the limbs
that show mylonitisationed by shear bands along the limbs that show
mylonitisation and rootless folds in quarzited bands. Thus it is
interpreted 3 interfernce patterns. The F2 folds are accompanied by shear
bands along the limbs that show mylonitisation and rootless folds in
interpreted that the mylonitisation is synkinematic with F2 stage of
folding. The mylonitic foliation has been refolded by F3 folds, which have
probably removed the shear fabric to a large extent due static
recrystallisation.
The Sangakiri Shear Zone separates the Idapadi Block from the
Salem Block. The shear zone shows dip towards north. The Salem Block
shows the dominants of metagabbro/mafic granulites have been
retrograded to amphibolites near Mallasamudram. The mylonitic foliation
strickes NE-SW and dips toward E. The amphibolite shows nappe
structure over the granite geneisses. The Kanjamalai shear zone near
Kanjamalai hill takes an easterly trend. The mylonitic foliation shows
NNW dip. The Udayapatti shear zone has an E-W strike and dips toward
north. The Udayapatti development. The mylonitic foliations are E-W and
dip north and contain down dip stretching lineation. The Umayalpuram
shear zone shows the emplacement of syenite and the mylonitic foliation
shows the southerly dip.The L.kanavaipatti shear zone is the
southernmost shear zone. The mylonites it is quite evident that the finite
strain varies from one block to another.
In Salem thrust sheet the static crsytallisation is very prominent while
the Namakkal thrust sheet retains the asymmetric fabric to a large
extent.
Fault: A limited metamorphic study has been conducted on
metagabbro/mafic granulites and from the namakkal Block. In Salem
thrust the static crystallization is very prominent Salem thrust sheet the
static crsytallisation is very prominent while the Namakkal thrust sheet
retains the asymmetric fabric to a large extent.
Several Faults and shears occurring in the study area. The major
shears noted are along SE face of the shevaroys showing well marked
strike-slip cleavage. Numbers of mylonite zones are found on the Western
part of the rugumalai, 5km East of Salem, parallel to the Attur valley and
cutting across the Kollihills and achamalai hills. The shears and fault are
more in the eastern part of the namakkal, bounding the hills.
Joints: The joint are well developed in the Charnockites, granites and
ultra mafic and are moderately developed is other intrusive rocks. The
major joints are vertical at places, showing step dips. There are a few
joints trending parallel to the fold axis. Similar type joints with varying
degree of dips and trends are found in the other parts of the study area.
Lineaments: The lineament map of Namakkal district has been
prepared from the LAND SAT and IRS imageries of scale 1:250000 by
visual image interpretation. Groundwater occurrences in most of the
boreholes, located in the lineaments, they are, NE-SW trending
lineaments, they are, NE-SW trending lineaments. N-S
trendinglineaments and NW-SE trending lineaments.
Shear zone: The palght Cauvery shear zone is a major shear zone that
possibly extends into fragments of Gondwanaland. In the present study
mafic granulites occurring on either side of the CSZ in Namakkal area,
southern India are examined.Textural features recorded in
themaficgranulites are crucial in elucidating the metamorphic history of
the southern granulite terrane.
Textural and P-T study of rocks occurring on either side of the
shear zone of the namakkal area has been attempted to understand its
significance and relevance to the tectonic evolution of the area. The
present study area is situated south of Namakkal comprising a segment
in the eastern part of the CSZ. Here, the CSZ is marked by the presence
of 2-3km wide E-W trending mylonitic gneisses, which are composed of
augen shaped quartz and feldspar grains and also consist of mica and
hornblende, situated on the northern bank of the Cauvery River.
Mafic granulite and granite migmatites occur on the northern
part of the CSZ while granitic gneisses constitute the southern part. Mafic
granulites usually occur as variably sized enclaves within the granitic
gneisses of the south. Hornblende biotite gneiss occurs as a thin band sub-
parallel to CsZ in the northern part.
Slope
Slope of an area is an indicator of the infiltrationrate. The contact
period of water with with the surface is less where the slope is more and
thereby the infiltration rate will be less. In places where the slope is
relatively less, the terrain is almost plain and the contact of the run off
water with surface is highand it results in good groundwater recharge.
The contour map is prepared in 1:50000 scale from SOI topo sheets. TIN
contour map is created from contour map.Based on the TIN map, slope
map is prepared for the study area. The slope map of the study area
reveals that the slope is high in hilly terrains which are present in north
and east parts.
