balasore report

Field tRip RepoRt

Semester 4

December 2015

Geographical Location: Balasore, North Orissa,

India

Geological Location: Singhbhum Craton

Team Name – Eclogite

Project by-

ABHIJEET SONI(14GG20003)

ARUSHI CHAUHAN (14EX20005)

AVINASH VENKATESH(14EX20006)

HIMESH KOTHARI(14EX20012)

KETAN KUMAR(14GG20019)

MUKESH CHANDAK(14EX20019)

RISHIKANTA JENA(14EX20025)

Acknowledgement

All our group members have contributed significantly in compiling

this project. However, it would not have been possible without the

kind support and help of our professors, Prof.ArindamBasu and

Prof.Abhijeet Mukherjee. We would like to extend our sincere

thanks to both of them.

We are highly indebted to Mr. Bikas Kumar Ram and Mr. Hemant

Singh for his guidance and constant supervision, providing

necessary information regarding the fieldtrip and for his extensive

support in completing the report.

INDEX INTRODUCTION

Objective

Study area and its Stratigraphy

Geological field work done in and around Balasore Location

Lithology Study of different composition Granite Geological structures

Data Analysis and Discussion

Rock samples pictures

Appendix

INTRODUCTION

Objective :To study the Geological aspect of the region around Balasore(North

Orrisa). Observing the different composition of minerals in Singhbum granite to

know the stratigraphy of the area. To observe the different grades of weathering.

This report is a brief synopsis of the Field Trip for the second year students of

2014-19 UG Batch of the Department of Geology and Geophysics, Indian Institute

of Technology, Kharagpur dated 7/12/2012 to 15/12/2012.

The area under analysis and observation is geographically located in Balasore,

North Orissa. Geologically, this region is a part of the Singhbhum Craton which is

considered to be one of the oldest and the first formed landmasses on Earth. The

Singhbhum Craton is an approximately 40000 sq. kms batholithic mass having

varied geological features, most of them relating to as old as the Pre-Cambrian Age.

According to Geological Survey of India, the region is well known for its rich

deposits of iron and copper. The rocks found in this region are Singhbhum Granite,

Hornblende Gneiss, Hornblende Granite, Dolerite, Granophyre and Red Laterite

rocks. Very old rocks like OMG(Older Metamorphic Group) and OMTG(Older

Metamorphic Tonalite Gneiss) which dates back to 3-4 Billion years.

Location-1 : NILAGIRI

Latitude – 21̊ 27 ̍ 53.4 ̎ N

Longitude – 86̊ 46 ̍ 11.8 ̎ E

Location on GSI Map

Location (fig 1.1)had singhbhum granite which are 3.8 billion years old. The

presence of an Unconfirmity is identified as unconsolidated sediments are present at

very close distance (according to the map).

According to Geological Survey of India, SinghbhumGranite ,a type of older metamorphic rock(OMG approx. 3.8billion years) is found in Nilagiri region. Considerable vegetation and light colored minerals are present in

The Nilagiri region, which is 25 km South West (SW) of Balasore , comprises of Crystalline Rocks.

: NILAGIRI

.1)had singhbhum granite which are 3.8 billion years old. The


close distance (according to the map).

According to Geological Survey of India, SinghbhumGranite ,a type of older metamorphic rock(OMG approx. 3.8billion years) is found in Nilagiri region. Considerable vegetation and light colored minerals are present in the nilagiri region.

The Nilagiri region, which is 25 km South West (SW) of Balasore , comprises of

.1)had singhbhum granite which are 3.8 billion years old. The


According to Geological Survey of India, SinghbhumGranite ,a type of older metamorphic rock(OMG approx. 3.8billion years) is found in Nilagiri region.

the nilagiri region.

The Nilagiri region, which is 25 km South West (SW) of Balasore , comprises of

On observing the rocks different minerals are identified on the basis of Lustre ,

Colour and Cleavage Planes and textures.

The minerals in the rocks are determined to be Quartz(fig 1.2), Plagioclase Feldspar, Muscovite (Small Quantity), Orthoclase Feldspar ( Small Quantity) and a Black Mineral (which cannot be easily determined) .

Quartz has Vitreous lustre and has no Cleavage Sets

Plagioclase Feldspar is White to Yellow in Colour, has lustre Sub-Vitreous and shines more than Quartz has cleavage sets.

Muscovite is a white coloured flaky mineral, having single cleavage plane.

Joints – A fracture dividing rock into two sections that have not moved away from each other . They occur in parallel sets and are distinguished from fractures and fault planes.

Fractures do not occur in parallel sets over a region but joints do occur

Faults are the fractures dividing rock into two sections that have moved away from each other.

Formation of Joints -

When magma crystallizes beneath the surface of the earth, Some parallel isothermal planes subnormal to which the stresses are maximum puts the either side of rock apart to form Joints.

Joints control the stability of rock because the magma while crystallizing separates into different rock along joint planes.

OBSERVATIONS –

Most of the rocks are Hard and Massive.

Distinct joint sets are observed in the rocks with moderate joint spacing.

Rocks are mostly weathered due to exposure to air, water and other physical conditions.

On the basis of our observation, we identified that there were three different clusters of joints as shown in stereogram.

Fig 1.1:Location Overview Fig 1.2: Quartz Cluster spread in the area

The attitude data of rocks were collected and are shown below:

TABLE 4:

Stereonet of the collected data :-

STEREONET 1

Location-2/6: MIRGUNI

Latitude – 21̊ 27 ̍ 1.9 ̎ N

Longitude – 86̊ 45 ̍ 24.54 ̎ E

Location on GSI Map

According to Geological Survey of India, Newer Dolerite Dykes intruded through

Singhbhum or Hornblende Granite basement

In this location newer dolerite dykes intruded through singhbhum granite basement, the country rock (Hornblende Granite). The region was a mining site. The site has a deep water reservoir, formed due to mining activities. Parts of the left over dykes were observed in some parts surrounding the reservoir with blackish appearance presumably comprising Dolerites.

The rocks are hard and massive. The Country rock of the region was granite with more content of Hornblende in it that’s why named as Hornblende Granites.

: MIRGUNI


Singhbhum or Hornblende Granite basement is found in Mirguni(Fig

In this location newer dolerite dykes intruded through singhbhum granite basement, ock (Hornblende Granite). The region was a mining site. The site has a

deep water reservoir, formed due to mining activities. Parts of the left over dykes were observed in some parts surrounding the reservoir with blackish appearance

Dolerites.



is found in Mirguni(Fig-2.1).

In this location newer dolerite dykes intruded through singhbhum granite basement, ock (Hornblende Granite). The region was a mining site. The site has a

deep water reservoir, formed due to mining activities. Parts of the left over dykes were observed in some parts surrounding the reservoir with blackish appearance


There are two types of rocks in the region –

1. Country Rock (Hornblende Granites) 2. Doleritic Dykes ( Comprising of Dolerites)

Hornblende Granite contains Quartz, Plagioclase Feldspar, Hornblende (In higher quantity than Singhbhum granites), Orthoclase Feldspar (Small Quantity), which are identified through their lustre, colour and cleavage planes.

Silica Veins are found in most of the rocks. It mainly comprises of Quartz. When Hydrothermal fluid extrudes up to the surface and settles in the country rock ,since Quartz is the last phase to crystallize according to Bowen reaction series ,Quartz settles in the fractures of the rocks hence forming the quartz Veins.

The colour of the rocks changes to yellow due to the action of rainwater, air and other factors (Physical Weathering).

The Country rock (Hornblende Granite ) is intruded by Dykes . The dykes mostly comprises of Dolerites which constitutes of Orthopyroxene and Plagioclase Feldspar. Dolerites are Hypabyssal igneous rocks. Although these are Plutonic igneous rocks which are formed beneath the surface, they come up to the surface mainly due to land upliftment and weathering, both of which are continuous processes and have been going on for about 3.8 billion years.

OBSERVATIONS –

Based on the stereonet plot, it is observed that 3 sets of joint planes are present in this region.

The Basement Rocks appeared to have gneissic trace over them. It is due to Instantaneous release of pressure over the rocks thus forming foliations over them.

Fig-2.1 : Location Overview Fig-2.2 : Specific joint sets

We visited Mirguni as our first site. A huge Dolerite Dyke which intruded the

country rock, Hornblende gniess made the whole exposure at Mirguni. Only some

parts of the dyke were observed as most parts had been taken out for economic

purpose. The rocks at the site had broken along the cooling joint planes(Fig-2.2)

due to some mining activities. The region also unconsolidated rocks broken off

from the country rock and dolorite dyke. Normally, Granite has very less amount of

hornblende but is rich in Biotite (about 4-5%) but the hornblende Granite/Gneiss

observed had considerable amount of Biotite along with Quartz and Plagioclase

with conspicuous amount of hornblende in the matrix. Quartz veins were found in

most of the rocks.The dyke cross-cutted the country rock which showed that the

dyke was younger than the country rock.

Thermal Exfoliation:Release of locked in stresses due to change in temperature.The

orthoclase content in the rock is more giving it a flashy colour.Sudden change in

atmospheric conditions induces uneven irregural expansions and contraction in rock

minerals which are different for different minerals resulting in foliation.

Contact Metamorphism:Metamorphosed granites are observed. It occurs due to

doleriticintrusion,which provides required conditions for metamorphism.

Quartz veins:Ptygmatic folding of veins are observed.Hydrothermal fluids extrudes

and settles in country rock(Hornblende Granite.Since quartz is the last phase to

crystalise according to Bowen Reaction Series hence the veins are composed of

quartz.

In the field grain size of country rock is relatively coarser than the intruded

dyke(dolerite).It is due to recrystallisation

Exfoliation surfaces was observed in the granite which happened due to diurnal

temperature difference. This happens in granite because it is hard and the

temperature variation between different layer was significant and grains are very

fine.

Fig-2.3 : Exfoliation Surface

Stereo Net of the collected Data:

STEREONET 2 AND 3

Location-3 :Bhalukasauni

Latitude – 21̊ 28 ̍ 48.6 ̎ N

Longitude- 86̊ 41 ̍ 30.9 ̎ E

Location on GSI Map

This location is about 10 kms south of Bhalukasuni Village (Fig 3.1). The site was

an active mining site with rocks having blue surface because of the active mining.

Most of the rocks were a part of igneous Dolerite with more of Dolerite (Fig 3.2),

having parallel cooling joints which were formed together in Singhbhum Granite.

There was little vegetation, plausibly because of the water seepage from the cracks

which might have been formed due to the on-going mining activities. The rocks in

this region are younger than the country rock because this is a dyke that cross-cut

the pre-existing country rock.

The country rock of the region is Diorite which can be identified through the minerals present in the rock Quartz, Plagioclase Feldspar (more abundant than Alkali Feldspar), Alkali feldspar, Hornblende, Mica (very small).

Diorite is composed of various dark coloured minerals which explain its black colouring. Diorite is a relatively finer grained than Granite rocks.

Compositional differences –

GRANITE – Content of (Alkali feldspar > Plagioclase Feldspar)

GRANODIORITE – Content of (Alkali Feldspar = Plagioclase Feldspar)

DIORITE – Content of (Alkali Feldspar < Plagioclase Feldspar)

The country Rocks of the region are older rocks .It is observed to be intruded by a dyke containing minerals Orthopyroxene and plagioclase .The dyke is fine grained , Dark Coloured . The minerals in it (plagioclase) has sub-vitreous lustre. Hence, the dyke is identified to be dolerite.

OBSERVATIONS –

The rocks showed distinct joint sets, which are parallel and very closely spaced. On plotting the data of the rocks on stereonet, clusters of poles are noticed in North-East, South-East and South – West Directions which defines specific Joint sets.

Fig-3.1:Location Overview Fig-3.2: Joint Planes

Most of the rock mass is the dolerite dyke.A huge vein of thick quartz which looks

bluish due to its thickness are found here(Fig-3.3).

Fig-3.3 : Bluish thick quartz

The collected data depicting the attitude of dolerite rocks at the site is shown

below.—

Stereo Net of the collected data:

STEREONET 4

Location-4: NARANGPUR (TOWARDS NORTH OF

BHALUKASUNI VILLAGE)

Latitude – 21° 30 ̍ 21.3 ̎ N

Longitude- 86̊ 72 ̍ 19 ̎ E

The region looked like an abandoned mining site with reddish black soil covering. A surface, one side of which has a pillow like structure and the other showing vesicular structure with distinct transition between the two. Possibly the vesicles might have formed due to release of trapped gases on cooling of lava and due to leaching.

The pillow like structure might have formed due to under water cooling of lava, water leached out most of the elements except Iron, Manganese, Aluminium and the laterite thus formed is a result of residual concentration.

Leaching – Leaching is the loss of mineral and organic solutes due to percolation. It is a mechanism of soil forming process of eluviation, which is the loss of mineral and organic colloids.

Laterization -

Billions of years ago , there might be some magma flow in the region and crystallized to form basaltic rocks. Laterites have a source rock. Thus they are called secondary rocks. The red colour is due to Ferric Oxide (Limonite – Coetite) . A possible hypothesis is that , the source rock ( Basalt) in the last millions of years has transformed to laterites .

The source rock contains (Fe-pyroxene and Feldspar). When water reacts with Fe-pyroxene and will leach out everything except Iron,Manganese and Aluminium .

When magma extrudes out from deep beneath the earth’s surface .It contains minerals like pyroxenes ,Quartz , Plagioclase etc..

Since , Pyroxene comes in contact with atmosphere having temperature around 300 Kelvin. It becomes unstable.It will convert to stable form of Ferric oxide. Quartz crystallizes at ~600°C which is much lower than Pyroxene , thus Quartz will be last to crystallize according to Bowen reaction Series hence , We observe shiny (glassy) particles in the region.

OBSERVATION -

Alternate red and black layered pattern was observed on the vertical cross sections of the site .A possible hypothesis may be that this might have formed because of several lava flows taking place at different intervals of time.

The inner surface might be more weathered because of water seepage through vesicles that acts like tunnels.

The upper layer of the soil is hard while the lower layer is soft. Also, the upper layer is vesicular , but the lower layer is having fine grained particles due to percolation of water.

Location-5 : DAHANIMARA

Latitude – 21̊ 28 ̍ 46.4 ̎ N

Longitude – 86̊ 45 ̍ 28.6 ̎ E

Location on GSI Map

This location (fig-5.1)showed us the whole

rock) to grade-6(soil).The soil layers had huge boulders known as “Core stones”

which might have been formed due to seepage of chemical weathering agent

through the fractures and joint planes.

The country rock of the region is Singhbhum Granite which can be identified by its

constituent minerals which are Hornblende (dark coloured), K

These minerals are identified on the basis of

It is fine grained and discoloured

Singhbhum Granite more Hornblende and Feldspar grains are altered.

In one of the selected areas the top soil layer is 5

grading of weathering of rocks below the topsurface

increases.

In the other area weathering grade of these rocks vary laterally significantly.The top

layer is grade 4 weathered while the underlying rocks are harder and show 2

weathering, this may primarily attribute to the i

5.1)showed us the whole process of weathering from grade

6(soil).The soil layers had huge boulders known as “Core stones”


through the fractures and joint planes.

region is Singhbhum Granite which can be identified by its

constituent minerals which are Hornblende (dark coloured), K-Feldspar and Quartz.

These minerals are identified on the basis of color, lustre and cleavage planes.

It is fine grained and discoloured due to weathering. In weathered part of


In one of the selected areas the top soil layer is 5-6 grade weathered while the

grading of weathering of rocks below the topsurface changes from 4


layer is grade 4 weathered while the underlying rocks are harder and show 2

weathering, this may primarily attribute to the influence of joints present there.

process of weathering from grade-1(bed

6(soil).The soil layers had huge boulders known as “Core stones”


region is Singhbhum Granite which can be identified by its

Feldspar and Quartz.

color, lustre and cleavage planes.

due to weathering. In weathered part of


6 grade weathered while the

changes from 4-6 as the depth


layer is grade 4 weathered while the underlying rocks are harder and show 2-3

nfluence of joints present there.

Fig-5.1 : Location Overview Fig-5.2 : Weathered Rocks

Stereonet of the collected data is :-

STEREONET 5

Location-6: MIRGUNI

Latitude – 21̊ 27 ̍ 1.9 ̎ N

Longitude – 86̊ 45 ̍ 24.54 ̎ E

Location on GSI Map

Location 7: PANCHALINGESHWAR: PANCHALINGESHWAR

Fig-5.1 : Location

The rocks observed here are called Granophyre (Fig 5.1). They are massive and

rounded due to the presence of feldspar in relatively higher amount. The minerals

that are identified (on the basis of colour, lustre,cleavage sets) to be present in large

amount are plagioclase feldspar, Quartz, Orthoclase feldspar.

The rocks are hard, fabricated and no joint planes are observed due to large in-

locked stresses acting within it. The hardness of these rocks could also be attributed

to its minerology and its typical microstructure.

Discussion

The Singhbhum Craton has rocks of various chronolological periods, different

geological features and evidences leading to various interesting hypothesis

regarding its formation.

The field trip starts at Nilagiri Region where we can find the oldest rocks of about

2.9 bya. The Singbhum Granite of about 2.9bya of Archaean Age, Newer Dolorite

Dykes and very young Proterozoic Laterite Deposits were found in the locations.

The region has a varied structural and lithological diversity. The hardness of the

rocks varied from easily crushable weathered Laterite to very hard Granophyre. The

Granophyre was highly massive and rounded whereas the Dolerite had sharp edges.

Distinct joint sets were observed in Singhbhum Granite, Hornblende

Granite/Gneiss, Dolerite but they were negligible in Granophyre and Laterite

Deposits.

Mineralogical differences were most prominent among the sites visited. Chemical

transformation of the minerals changed the rock type from Singhbum granite to

Hornblende Gniess. This all happened due to the magmatic differentiation during

the formation of rocks. Location-1 and Location-2 had newer Dolerite Dykes

whereas Locations 3,4,5 did not have any traces of Dolerite Dyke. Joint Planes were

more prominent and clearly visible at Location no. 1 and 2 compared to Locations

3,4,5. Location 3 gave us a complete picture of the grades of weathering(Fig-6).

The hardest rock we came across was Grannophyre found at location 5.

Fig-6 : Weathering Profile

Some Rock samples we came across during this field trip

Quartz Dolerite

Hornblende Granite

STEREONET 1 DATA :

APPENDIX

STEREONET 3 DATA:

STEREONET 4 DATA:

FUNDAMENTALS OF HISTORICAL GEOLOGY and STRATIGRAPHY

- RAVINDRA KUMAR (2006)

balasore report

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