Geological Field Work in and
around Maithon & Jitpur
Department of Geology, Durgapur Govt. College
B. Sc. HONOURS
|
1st SEMESTER
NAME: ARITRA BANERJEE
COLLEGE ROLL NO. : 24GELH006
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The geological field work was conducted at Maithon, Kalyaneshwari in West
Burdwan district , was arranged for the 1stYear Geology Honours students of
Durgapur Govt. College
DESCRIPTION OF THE FIELD AREA
Location :- Maithon
Latitude :- 23°46.919’ N
Longitude:- 86°49.710’ E
Temperature:- 20*- 24*C
The area falls under the Survey of India Toposheet no - 73/I/13 .
Duration of field work – 28th Nov to 1st Dec, 2024
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1.To learn the fundamental methods like measurement of attitude of beds and foliation of rocks ,map
orientation ,plotting locations on map etc which are essential for geological field work.
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2.To study the different exposures of sedimentary rocks with fossil bearing units, igneous and
metamorphic rocks.
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3. To study the litho units in terms of their location, hand specimens, along with the measurement of
structural data (attitude of linear and planar structures, true bed thickness) and understanding the
modes of occurrence of the different litho units and their inter relationships.
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4.Also to learn about the use of the geological instruments (Brunton Compass, hammer, pocket
lens, diagonal scale) and to collect samples for future references.
STRATIGRAPHIC COLUMN :-
TALCHIR (ODISSA),
GONDOWANA
UNCONFORMITY
PRECAMBRIAN
Chota Nagpur
Gneissic Complex
(GRANITIC GNEISE,
AMPHIBOLITE)
KAHARBARI (JITPUR),
BARAKAR,
BARREN MEASURE
(KULTI),
RANIGUNJ
We have covered 15 locations in an around Maithon, starting from L
1 to L 15
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Brunton Compass: It is used to get directional degree measurements (azimuth) through use of the
Earth's magnetic field. Holding the compass at waist-height, we look down into the mirror and lines up the target,
needle, and guide line that is on the mirror.
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Hammer & Chisel: Another important tool for us was the hammer. A hammer for geological
purpose must have a chisel opposite to the flat end. The chisel helpful in breaking rocks for taking samples.
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Diagonal Scale: For measuring both the length (of small dimensions) and the angle between two
linear elements, a diagonal scale is used. It is a simple 15cm scale with markings of degrees like a
protractor from 0°-90°.
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Pocket Lens: Last but not the least is the simple 10x pocket lens. It has optical magnification of 10x
and is indispensable while identifying the mineral composition of a rock.
Strike and Dip Measurement :1.
Considered the foliation plane.
2.
Placed the Brunton compass horizontally on the rock as the water drop of cylindrical container point
at the marked point.
3.
Marked the point on the rock as a line , called strike line.
4.
Then adjusted the compass in such a way so that the drop of round container should come in the
centre and measured the angle towards north. This is called strike.
5.
Thereafter to measure Dip direction we measured perpendicular to the strike . To measure Dip we
were focusing the clinometer scale at 0 with Brunton compass scale , then adjusted the drop of
circular scale as the drop focus at the centre of the circle of the container , took reading of
Clinometer scale . This is called Dip and at which direction the foliation plane allied is called Dip
direction .
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Back Bearing Process :- To plot our location with respect to other land form we use back
bearing process . Firstly we choose an landform , then adjust it as it’s top most point ,the pin
point of brunton compass allied in the same line of brunton’s mirror , then take the reading of
the point and same procedure apply in another landform then from the angle of those points
draws two straight line . Those lines are intersect at which position , was our location .
Trench and Plunge :- The measurement of trench is the same process like strike and
plunge is the same process like Dip for Lineation .
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Recognition of rock types:
All the three types of rocks (Igneous, Sedimentary and Metamorphic) are found in Maithon.
The recognition of these different types of rocks during field work was done basically by
distinguishing their mineral content, dominant texture and a lot of help from the
teachers.
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Metamorphic rocks: They are dominantly composed of biotite, amphibole, quartz
and feldspar. The mineralogy is not much distinctive from igneous rocks, but their
texture is very different from the latter. The mafic and felsic parts of the rocks are
generally compositionally segregated into thin or thick bands known as schistosity or
gneissosity of the rocks.
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Igneous rocks:
In Maithon, the igneous rocks are mostly of mafic composition,
hence dark in colour (melanocratic). Dominant mineralogy is biotite, hornblende, and
pyroxene with plagioclase feldspar. Interlocking textures are common.
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Sedimentary rocks: They are easily recognized due to their clastic texture, presence
of framework, matrix and cement. The dominant mineralogy is rounded quartz and
feldspar grains within siliceous matrix.
Location
Igneous
Sedimentory
Metamorphic
L1
Nill
Nill
Fine grain Amphibolite
(Quartz, Amphiboles,
Hornblend, Plagioclase
Feldspar.)
L2
Granite (Plagioclase
Feldspar , Mica , Quartz,
Pottas Feldspar)
Nill
Nill
L3
Nill
Nill
Hornblend Gneisse
(Amphiboles , Mica,
Quartz)
L4
Nill
Nill
Folliated Amphibolite
L5
Nill
Nill
Quartz Vein folding S
type. Amphibolitic
Gneisse.
L6
Nill
Sand Stone
Nill
L7
Nill
Sand Stone ( Mica with
Iron Leaching) , Pot hole.
Nill
L8
Nill
Fine Grains Silt Stone
Nill
L9
Nill
Nill
Granitic Gneisse ( Pottas
Feldspar , Plagioclase
Feldspar , Quartz) ,
Augen Gneisse.
L 10
Nill
Nill
Gneissic Drop Stone
(Feldspar , Quartz) ,
Location
Igneous
Sedimentory
Metamorphic
L 11
Nill
Sand Stone ,
Trace Fossil
(Rhyzocorallium ,
Planolite)
Nill
L 12
Nill
Nill
Granitic Gneisse with
Bolder Bed ,
Conglomerate
L 14
Nill
Nill
Amphibolite (Plagioclase
Feldspar , Amphiboles,
Clinopyroxene).
L 15
Nill
Nill
Amphibolite ((Quartz,
Mica, Amphiboles,
Hornblend, Plagioclase
Feldspar = Albite +
Anthrite) , Pottas
Feldspar vein , Quartz
Vein, Dolorite Vein,
L 13 :- Detail description of Maithon Dam .
Exfoliation
S type Fold
Fine Grain Amphibolite
Ripple Like Structure on Silt
Stone
Pot Hole
Silt stone
Amphibolite Gneisse With
Quartz Vein
Quartz Vein
Sand Stone
Dolorite Vein
Sharp contact with Quartz
Granitic Gneisse
Pinch and Swell
Trace Fossil
Bolder beded Sand Stone
Augen Gneisse
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Any structure, that develops prior to or during deformation of rocks are called primary structures. These are nontectonic, meaning they for during sedimentary deposition or in case of metamorphic rock, during
crystallization.
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1. CROSS BEDDING :- The drifted sandstones on the exposure at Jitpur had richly developed cross beddings.
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2. SOLE MARKS :- It was observed in Gondwana section.
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3. PLANAR LAMINA: The sandstones present behind the Kalyaneshwari temple , bank of nala which meets
with Barakar river showed excellent planar lamina as well as planar cross stratification.
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4. RIPPLE MARKS: Ripple marks were observed on the bank of Barakar river.
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5.FOLIATION PLANES (SCHISTOSITY) : Foliation planes (schistosity) were present in metamorphic rock
like amphibolites on the road side towards reservoir.
Deformational Structures
These structures show deformation that occurred during or after deposition..
1. FOLDS: Folds were observed behind Kalyaneswari Temple.
2. PINCH AND SWELL STRUCTURES: were observed behind Kalyaneswari Temple.
3.LINEATION: Lineations were present in gneissic rocks found behind the Kalyaneshwari
temple. The lineation containing rock was sand stone.
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Great thanks goes to our Teachers Prof. Dr. Supratim Pal and Prof. Dr. Pinaki Roy
for guiding us throughout the Field work.
I am thankful to my fellow classmates for their help in collecting detailed
photographs and notes.
 Thank You