SlideShare a Scribd company logo
1 of 31
Download to read offline
INTRUSIVE IGNEOUS
ROCKS
M.RAJASEKHAR
ASST.PROFESSOR
DEPARTMENT OF CIVIL
ENGINEERING
KUPPAM ENGINEERING COLLEGE, KUPPAM
FORMS OF INTRUSIVE IGNEOUS ROCKS
• Commonly observed forms of Plutonic (intrusive) rocks
observed in the field are: dykes, sills, laccoliths, bysmaliths,
phacoliths, lopolith, volcanic necks, batholiths and
chonoliths.
• Based on the attitudes of the associated country rocks the forms
are called either as Concordant or Discordant.
DYKES: Dykes and sills are the most common forms of the
intrusive igneous bodies.
• They are discordant
• Cut across the bedding of the rocks in which
they intrude
• Vertical to steeply inclined and sheetlike
body (extensive in lateral dimension)
• Thickness vary widely from an inch upto
hundred of feet
• Injected through fractures, joints, and weak
planes
• Quartz-Dolerite dykes of Midland valley of Scotland are
about 50-60 km long and upto 30m thick. Few places some
dykes are very short upto few meters and as thin as few
cm.
Mafic
dyke
eg. Lamprophyric rocks broadly represented by kimberlites.
Lamprophyre dykes are located close to the western and
eastern margins of the Cuddapah basin in the eastern
Dharwar craton of India.
SILLS: Sills are relatively thin tabular sheetlike body that
penetrates parallel to the bedding planes.
• Laterally it may extends for 100s of km and upto 10 km in
width.
• Lateral extend mainly depends on the hydrostatic force,
temperature, degree of fluidity or viscosity, weight of
overlying sediment column.
• Since basic magma are more fluid then acidic magma-
mostly sills are made up of gabbros, dolerites and basalts
mudstone
sandstone
limestone
Spreads parallel to the bedding
planes of the rocks, hence
concordant in nature.
Example Large Sill
LACCOLITHS: It is a concordant body, with flat bottom
and convex upward. It is dome shaped.
When viscous magma is
injected rapidly along
the bedding, as it cannot
spreads it pushes up the
overlying layers and
keep on piling up.
It causes folding of the
overlying rock layers.
Figure 4-26. Shapes of two concordant plutons.
a. Laccoliths with flat floor and arched roof.
b. Lopolith intruded into a structural basin. The scale is not
the same for these two plutons, a lopolith is generally much
larger.
Structures and Field Relationships
BYSMALITH: It is cylindrically shaped body.
• It is developed when highly viscous magma is injected,
because the lateral spreading along the bedding is less it
acquires to move upwards and form cylindrical shape.
• Causes breaking of overlying rock layers.
• Their side sloping away from each other which makes them larger
and large downwards extending to greater depth
• It may be occur discordant and concordant forms of igneous rocks
• The irregular masses appears on the batholiths are called stocks
and circulars masses are bosses
• Their occurrence is commonly associated with the mountain-
building process
• These are either granites or granodiorites in composition
BATHOLITHS: are the largest kind of plutons, irregular in
shape and occupies large area.
Stocks: Are smaller irregular
bodies with 10 km in maximum
dimension, and are associated
with batholiths.
PHACOLITHS: These are concordant bodies that occurs
along the crests and troughs of the folded
sedimentary strata.
LOPOLITHS: These are basin or saucer-shaped concordant
bodies with top nearly flat and convex bottom
• They are very huge body with diameter upto 150 miles
(app. 240 km)
Lopolith
CHONOLITHS: This term is applied to all other intrusive
igneous bodies with irregular shape, i.e. the
body with no specific shape.
VOLCANIC NECK or VOLCANIC PLUGS: It is
cylindrical conduit that fed magma upward to a volcanic
vent or it is a conduit of the ancient volcano. Vary in
diameter from a few 100s of m to a kilometer or more.
These are filled up with crystalline rocks.
Shape-circular, elliptical or irregular.
TEXTURES OF IGNEOUS ROCKS
• Texture is defined as the overall appearance of a rock
based on size, shape and arrangement of interlocking
minerals
• Texture depends on their
• (a) Granularity (b) Crystalanity ( C) Shape of crystals
• Based on granularity or grain size:
Grain size depends on physical conditions that prevailed during
the time of Crystallization of magma
i.e. presence of volatiles, rate of cooling, pressure, temperature etc.
Slow cooling = larger mineral grains
Fast cooling = smaller mineral grains
PHANERIC TEXTURE
Is characterized by LARGE SIZE MINERALS which can be
easily seen by Naked eye (size at least 2mm or greater)
Coarse-grained
Phaneric
- > 5mm
Medium-grained
Phaneric
- 1 mm - 5mm
Fine-grained
Aphanitic
<1 mm
Commonly associated with the INTRUSIVE (PLUTONIC)
IGNEOUS ROCKS, because magma in the crust cools at
slower rate and have enough time to result into large mineral
grains.
Eg. Granite; Pegmatite
DIORITE
GABBRO
APHANITIC TEXTURE
Is characterized by FINE GRAINED MINERALS, which can
be seen under microscope (size < 1mm)
Commonly associated with the VOLCANIC (EXTRUSIVE)
IGNEOUS ROCKS, because magma on the surface flows
cools faster.
Eg. Basalts; Rhyolite
Basalt
Rhyolite
Obsidian
Based on crystalanity or definite shape:
• Crystals are bodies bounded by surfaces, having definite shape
by the internal arrangement of atoms
i.e. Solidification of minerals from the gaseous or liquid states or from solutions
Crystalanity grouped into three types based upon the shape of
crystals formation they are
Holo Crystalline
: A rock composed of
mostly crystals
Hemi crystalline
: A rock composed of partly
crystals and glassy
Holo hyaline
: A rock composed of
completely glassy matter
Based on Shape of the crystals
• The pattern or fabric of a rock depends on the shape as well as
relative size and arrangement of the minerals.
The shape of the mineral grains in igneous rocks may be broadly
grouped into three types
Euhedral
: Minerals are developed
equally in size and shape
and are completely
bound with faces
Sub hedral
: Minerals are developed
partially or to an intermediate
state
Anhedral
Minerals are developed
irregular shapes because their
growth is controlled by
neighboring materials
This happens when slow cooling is followed by rapid cooling.
Phenocrysts = larger crystals, matrix or groundmass = smaller
crystals
]PORPHYRITIC TEXTURE
Is a distinctive mixture of large and fine grained mineral grains
ANDESITE PROPHYERY
Phenocrysts of Amphibole Ground mass mainly of
Plagioclase feldspar (Na/Ca)
Forms of igneous rocks
Forms of igneous rocks
Forms of igneous rocks

More Related Content

What's hot

primary sedimentary structures
primary sedimentary structuresprimary sedimentary structures
primary sedimentary structurespolarocky
 
Foliation and lineation
Foliation and lineationFoliation and lineation
Foliation and lineationSaad Raja
 
Rock cleavage, foliation and lineation and their various types of formations
Rock cleavage, foliation and lineation and their various types of formationsRock cleavage, foliation and lineation and their various types of formations
Rock cleavage, foliation and lineation and their various types of formationsSharik Shamsudhien
 
Primary structures of sedimentary and igneous rocks
Primary structures of sedimentary and  igneous rocksPrimary structures of sedimentary and  igneous rocks
Primary structures of sedimentary and igneous rocksOmer M. Ahmed
 
Southern granulite
Southern granuliteSouthern granulite
Southern granuliteSANDIP1992
 
Metamorphic textures
Metamorphic  texturesMetamorphic  textures
Metamorphic texturesPramoda Raj
 
Shear zones.
Shear zones.Shear zones.
Shear zones.urbez
 
Stress and strain ellipsoid
Stress and strain ellipsoidStress and strain ellipsoid
Stress and strain ellipsoidPramoda Raj
 
SEDIMENTARY BASINS OF INDIA.pptx
SEDIMENTARY BASINS OF INDIA.pptxSEDIMENTARY BASINS OF INDIA.pptx
SEDIMENTARY BASINS OF INDIA.pptxBARKAVE BALUSAMY
 
Sedimentary structure
Sedimentary structureSedimentary structure
Sedimentary structurePramoda Raj
 
Ichnology,classification & significance of trace fossil
Ichnology,classification & significance of trace fossilIchnology,classification & significance of trace fossil
Ichnology,classification & significance of trace fossilUjjavalPatel16
 
Mantle melting and Magmatic processes
Mantle melting and Magmatic processesMantle melting and Magmatic processes
Mantle melting and Magmatic processesAnanya21Mittal
 
Lineation And Linear structural
Lineation And Linear structuralLineation And Linear structural
Lineation And Linear structuralSaif Abo Khashaba
 

What's hot (20)

Forms of igneous rocks
Forms of igneous rocksForms of igneous rocks
Forms of igneous rocks
 
primary sedimentary structures
primary sedimentary structuresprimary sedimentary structures
primary sedimentary structures
 
Foliation and lineation
Foliation and lineationFoliation and lineation
Foliation and lineation
 
Rock cleavage, foliation and lineation and their various types of formations
Rock cleavage, foliation and lineation and their various types of formationsRock cleavage, foliation and lineation and their various types of formations
Rock cleavage, foliation and lineation and their various types of formations
 
Primary structures of sedimentary and igneous rocks
Primary structures of sedimentary and  igneous rocksPrimary structures of sedimentary and  igneous rocks
Primary structures of sedimentary and igneous rocks
 
Southern granulite
Southern granuliteSouthern granulite
Southern granulite
 
Metamorphic textures
Metamorphic  texturesMetamorphic  textures
Metamorphic textures
 
Shear zones.
Shear zones.Shear zones.
Shear zones.
 
Paleozoic stratigraphy
Paleozoic stratigraphy Paleozoic stratigraphy
Paleozoic stratigraphy
 
Anorthosite
AnorthositeAnorthosite
Anorthosite
 
Classification of Sandstone
Classification of SandstoneClassification of Sandstone
Classification of Sandstone
 
Stress and strain ellipsoid
Stress and strain ellipsoidStress and strain ellipsoid
Stress and strain ellipsoid
 
Lamprophyre
LamprophyreLamprophyre
Lamprophyre
 
THE ORE-BEARING FLUIDS
THE ORE-BEARING FLUIDSTHE ORE-BEARING FLUIDS
THE ORE-BEARING FLUIDS
 
SEDIMENTARY BASINS OF INDIA.pptx
SEDIMENTARY BASINS OF INDIA.pptxSEDIMENTARY BASINS OF INDIA.pptx
SEDIMENTARY BASINS OF INDIA.pptx
 
Sedimentary structure
Sedimentary structureSedimentary structure
Sedimentary structure
 
Lineation
Lineation Lineation
Lineation
 
Ichnology,classification & significance of trace fossil
Ichnology,classification & significance of trace fossilIchnology,classification & significance of trace fossil
Ichnology,classification & significance of trace fossil
 
Mantle melting and Magmatic processes
Mantle melting and Magmatic processesMantle melting and Magmatic processes
Mantle melting and Magmatic processes
 
Lineation And Linear structural
Lineation And Linear structuralLineation And Linear structural
Lineation And Linear structural
 

Similar to Forms of igneous rocks

Lecture 03 igeneous rock
Lecture 03 igeneous rockLecture 03 igeneous rock
Lecture 03 igeneous rockHamza Chaudhry
 
Plugs and plutons.
Plugs and plutons.Plugs and plutons.
Plugs and plutons.poojaumishra
 
Igneous rock, Engineering Geology, Semester IV GTU
Igneous rock, Engineering Geology, Semester IV GTUIgneous rock, Engineering Geology, Semester IV GTU
Igneous rock, Engineering Geology, Semester IV GTUketgold
 
Igneous structure and genesis (structural geology)
Igneous structure and genesis (structural geology)Igneous structure and genesis (structural geology)
Igneous structure and genesis (structural geology)Shivam Jain
 
11 formation of rock layers
11 formation of rock layers11 formation of rock layers
11 formation of rock layersAriel Motas
 
Structure of Igneous Rocks
Structure of Igneous RocksStructure of Igneous Rocks
Structure of Igneous Rockssatyamsahu61
 
Lecture # 02, 03 316 geology and earth quake engineering 5th
Lecture # 02, 03  316 geology and earth quake engineering  5thLecture # 02, 03  316 geology and earth quake engineering  5th
Lecture # 02, 03 316 geology and earth quake engineering 5thEngrHayatHussain
 
ON petrology-geology.ppt
ON petrology-geology.pptON petrology-geology.ppt
ON petrology-geology.pptDrAnirbanMandal
 
11formationofrocklayers-201115152616.pptx
11formationofrocklayers-201115152616.pptx11formationofrocklayers-201115152616.pptx
11formationofrocklayers-201115152616.pptxcjoypingaron
 
Characteristics of sedimentary rocks
Characteristics of sedimentary rocksCharacteristics of sedimentary rocks
Characteristics of sedimentary rocksDr Robert Craig PhD
 
1. UNIT _ I Building Materials Stones.pptx
1. UNIT _ I Building Materials Stones.pptx1. UNIT _ I Building Materials Stones.pptx
1. UNIT _ I Building Materials Stones.pptxraju863386
 

Similar to Forms of igneous rocks (20)

Igneous rocks
Igneous rocksIgneous rocks
Igneous rocks
 
1 igneous
1 igneous1 igneous
1 igneous
 
Lecture 03 igeneous rock
Lecture 03 igeneous rockLecture 03 igeneous rock
Lecture 03 igeneous rock
 
Engg geology
Engg geologyEngg geology
Engg geology
 
Plugs and plutons.
Plugs and plutons.Plugs and plutons.
Plugs and plutons.
 
Igneous rock, Engineering Geology, Semester IV GTU
Igneous rock, Engineering Geology, Semester IV GTUIgneous rock, Engineering Geology, Semester IV GTU
Igneous rock, Engineering Geology, Semester IV GTU
 
L01_Intoduction.pptx
L01_Intoduction.pptxL01_Intoduction.pptx
L01_Intoduction.pptx
 
Igneous structure and genesis (structural geology)
Igneous structure and genesis (structural geology)Igneous structure and genesis (structural geology)
Igneous structure and genesis (structural geology)
 
Building Stones.pdf
Building Stones.pdfBuilding Stones.pdf
Building Stones.pdf
 
Building Stones
Building StonesBuilding Stones
Building Stones
 
E.g ex 3 igneous rocks (2015-16 )
E.g  ex 3 igneous rocks (2015-16 )E.g  ex 3 igneous rocks (2015-16 )
E.g ex 3 igneous rocks (2015-16 )
 
11 formation of rock layers
11 formation of rock layers11 formation of rock layers
11 formation of rock layers
 
Structure of Igneous Rocks
Structure of Igneous RocksStructure of Igneous Rocks
Structure of Igneous Rocks
 
Lecture # 02, 03 316 geology and earth quake engineering 5th
Lecture # 02, 03  316 geology and earth quake engineering  5thLecture # 02, 03  316 geology and earth quake engineering  5th
Lecture # 02, 03 316 geology and earth quake engineering 5th
 
ON petrology-geology.ppt
ON petrology-geology.pptON petrology-geology.ppt
ON petrology-geology.ppt
 
11formationofrocklayers-201115152616.pptx
11formationofrocklayers-201115152616.pptx11formationofrocklayers-201115152616.pptx
11formationofrocklayers-201115152616.pptx
 
Igneous rocks
Igneous rocksIgneous rocks
Igneous rocks
 
Characteristics of sedimentary rocks
Characteristics of sedimentary rocksCharacteristics of sedimentary rocks
Characteristics of sedimentary rocks
 
4.petrology.pptx
4.petrology.pptx4.petrology.pptx
4.petrology.pptx
 
1. UNIT _ I Building Materials Stones.pptx
1. UNIT _ I Building Materials Stones.pptx1. UNIT _ I Building Materials Stones.pptx
1. UNIT _ I Building Materials Stones.pptx
 

Recently uploaded

geometric quantization on coadjoint orbits
geometric quantization on coadjoint orbitsgeometric quantization on coadjoint orbits
geometric quantization on coadjoint orbitsHassan Jolany
 
soft skills question paper set for bba ca
soft skills question paper set for bba casoft skills question paper set for bba ca
soft skills question paper set for bba caohsadfeeling
 
Identification of Superclusters and Their Properties in the Sloan Digital Sky...
Identification of Superclusters and Their Properties in the Sloan Digital Sky...Identification of Superclusters and Their Properties in the Sloan Digital Sky...
Identification of Superclusters and Their Properties in the Sloan Digital Sky...Sérgio Sacani
 
Principles & Formulation of Hair Care Products
Principles & Formulation of Hair Care  ProductsPrinciples & Formulation of Hair Care  Products
Principles & Formulation of Hair Care Productspurwaborkar@gmail.com
 
Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...
Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...
Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...Sérgio Sacani
 
Contracts with Interdependent Preferences (2)
Contracts with Interdependent Preferences (2)Contracts with Interdependent Preferences (2)
Contracts with Interdependent Preferences (2)GRAPE
 
biosynthesis of the cell wall and antibiotics
biosynthesis of the cell wall and antibioticsbiosynthesis of the cell wall and antibiotics
biosynthesis of the cell wall and antibioticsSafaFallah
 
Human brain.. It's parts and function.
Human brain.. It's parts and function. Human brain.. It's parts and function.
Human brain.. It's parts and function. MUKTA MANJARI SAHOO
 
Pests of tenai_Identification,Binomics_Dr.UPR
Pests of tenai_Identification,Binomics_Dr.UPRPests of tenai_Identification,Binomics_Dr.UPR
Pests of tenai_Identification,Binomics_Dr.UPRPirithiRaju
 
Bureau of Indian Standards Specification of Shampoo.pptx
Bureau of Indian Standards Specification of Shampoo.pptxBureau of Indian Standards Specification of Shampoo.pptx
Bureau of Indian Standards Specification of Shampoo.pptxkastureyashashree
 
Pests of ragi_Identification, Binomics_Dr.UPR
Pests of ragi_Identification, Binomics_Dr.UPRPests of ragi_Identification, Binomics_Dr.UPR
Pests of ragi_Identification, Binomics_Dr.UPRPirithiRaju
 
SUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdf
SUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdfSUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdf
SUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdfsantiagojoderickdoma
 
001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...
001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...
001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...marwaahmad357
 
TORSION IN GASTROPODS- Anatomical event (Zoology)
TORSION IN GASTROPODS- Anatomical event (Zoology)TORSION IN GASTROPODS- Anatomical event (Zoology)
TORSION IN GASTROPODS- Anatomical event (Zoology)chatterjeesoumili50
 
RCPE terms and cycles scenarios as of March 2024
RCPE terms and cycles scenarios as of March 2024RCPE terms and cycles scenarios as of March 2024
RCPE terms and cycles scenarios as of March 2024suelcarter1
 
PSP3 employability assessment form .docx
PSP3 employability assessment form .docxPSP3 employability assessment form .docx
PSP3 employability assessment form .docxmarwaahmad357
 
Physics Serway Jewett 6th edition for Scientists and Engineers
Physics Serway Jewett 6th edition for Scientists and EngineersPhysics Serway Jewett 6th edition for Scientists and Engineers
Physics Serway Jewett 6th edition for Scientists and EngineersAndreaLucarelli
 
Application of Foraminiferal Ecology- Rahul.pptx
Application of Foraminiferal Ecology- Rahul.pptxApplication of Foraminiferal Ecology- Rahul.pptx
Application of Foraminiferal Ecology- Rahul.pptxRahulVishwakarma71547
 
Basic Concepts in Pharmacology in molecular .pptx
Basic Concepts in Pharmacology in molecular  .pptxBasic Concepts in Pharmacology in molecular  .pptx
Basic Concepts in Pharmacology in molecular .pptxVijayaKumarR28
 

Recently uploaded (20)

geometric quantization on coadjoint orbits
geometric quantization on coadjoint orbitsgeometric quantization on coadjoint orbits
geometric quantization on coadjoint orbits
 
soft skills question paper set for bba ca
soft skills question paper set for bba casoft skills question paper set for bba ca
soft skills question paper set for bba ca
 
Identification of Superclusters and Their Properties in the Sloan Digital Sky...
Identification of Superclusters and Their Properties in the Sloan Digital Sky...Identification of Superclusters and Their Properties in the Sloan Digital Sky...
Identification of Superclusters and Their Properties in the Sloan Digital Sky...
 
Principles & Formulation of Hair Care Products
Principles & Formulation of Hair Care  ProductsPrinciples & Formulation of Hair Care  Products
Principles & Formulation of Hair Care Products
 
Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...
Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...
Digitized Continuous Magnetic Recordings for the August/September 1859 Storms...
 
Data delivery from the US-EPA Center for Computational Toxicology and Exposur...
Data delivery from the US-EPA Center for Computational Toxicology and Exposur...Data delivery from the US-EPA Center for Computational Toxicology and Exposur...
Data delivery from the US-EPA Center for Computational Toxicology and Exposur...
 
Contracts with Interdependent Preferences (2)
Contracts with Interdependent Preferences (2)Contracts with Interdependent Preferences (2)
Contracts with Interdependent Preferences (2)
 
biosynthesis of the cell wall and antibiotics
biosynthesis of the cell wall and antibioticsbiosynthesis of the cell wall and antibiotics
biosynthesis of the cell wall and antibiotics
 
Human brain.. It's parts and function.
Human brain.. It's parts and function. Human brain.. It's parts and function.
Human brain.. It's parts and function.
 
Pests of tenai_Identification,Binomics_Dr.UPR
Pests of tenai_Identification,Binomics_Dr.UPRPests of tenai_Identification,Binomics_Dr.UPR
Pests of tenai_Identification,Binomics_Dr.UPR
 
Bureau of Indian Standards Specification of Shampoo.pptx
Bureau of Indian Standards Specification of Shampoo.pptxBureau of Indian Standards Specification of Shampoo.pptx
Bureau of Indian Standards Specification of Shampoo.pptx
 
Pests of ragi_Identification, Binomics_Dr.UPR
Pests of ragi_Identification, Binomics_Dr.UPRPests of ragi_Identification, Binomics_Dr.UPR
Pests of ragi_Identification, Binomics_Dr.UPR
 
SUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdf
SUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdfSUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdf
SUKDANAN DIAGNOSTIC TEST IN PHYSICAL SCIENCE ANSWER KEYY.pdf
 
001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...
001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...
001 Case Study - Submission Point_c1051231_attempt_2023-11-23-14-08-42_ABS CW...
 
TORSION IN GASTROPODS- Anatomical event (Zoology)
TORSION IN GASTROPODS- Anatomical event (Zoology)TORSION IN GASTROPODS- Anatomical event (Zoology)
TORSION IN GASTROPODS- Anatomical event (Zoology)
 
RCPE terms and cycles scenarios as of March 2024
RCPE terms and cycles scenarios as of March 2024RCPE terms and cycles scenarios as of March 2024
RCPE terms and cycles scenarios as of March 2024
 
PSP3 employability assessment form .docx
PSP3 employability assessment form .docxPSP3 employability assessment form .docx
PSP3 employability assessment form .docx
 
Physics Serway Jewett 6th edition for Scientists and Engineers
Physics Serway Jewett 6th edition for Scientists and EngineersPhysics Serway Jewett 6th edition for Scientists and Engineers
Physics Serway Jewett 6th edition for Scientists and Engineers
 
Application of Foraminiferal Ecology- Rahul.pptx
Application of Foraminiferal Ecology- Rahul.pptxApplication of Foraminiferal Ecology- Rahul.pptx
Application of Foraminiferal Ecology- Rahul.pptx
 
Basic Concepts in Pharmacology in molecular .pptx
Basic Concepts in Pharmacology in molecular  .pptxBasic Concepts in Pharmacology in molecular  .pptx
Basic Concepts in Pharmacology in molecular .pptx
 

Forms of igneous rocks

  • 1. INTRUSIVE IGNEOUS ROCKS M.RAJASEKHAR ASST.PROFESSOR DEPARTMENT OF CIVIL ENGINEERING KUPPAM ENGINEERING COLLEGE, KUPPAM
  • 2. FORMS OF INTRUSIVE IGNEOUS ROCKS • Commonly observed forms of Plutonic (intrusive) rocks observed in the field are: dykes, sills, laccoliths, bysmaliths, phacoliths, lopolith, volcanic necks, batholiths and chonoliths. • Based on the attitudes of the associated country rocks the forms are called either as Concordant or Discordant.
  • 3. DYKES: Dykes and sills are the most common forms of the intrusive igneous bodies. • They are discordant • Cut across the bedding of the rocks in which they intrude • Vertical to steeply inclined and sheetlike body (extensive in lateral dimension) • Thickness vary widely from an inch upto hundred of feet • Injected through fractures, joints, and weak planes
  • 4. • Quartz-Dolerite dykes of Midland valley of Scotland are about 50-60 km long and upto 30m thick. Few places some dykes are very short upto few meters and as thin as few cm. Mafic dyke
  • 5. eg. Lamprophyric rocks broadly represented by kimberlites. Lamprophyre dykes are located close to the western and eastern margins of the Cuddapah basin in the eastern Dharwar craton of India.
  • 6. SILLS: Sills are relatively thin tabular sheetlike body that penetrates parallel to the bedding planes. • Laterally it may extends for 100s of km and upto 10 km in width. • Lateral extend mainly depends on the hydrostatic force, temperature, degree of fluidity or viscosity, weight of overlying sediment column. • Since basic magma are more fluid then acidic magma- mostly sills are made up of gabbros, dolerites and basalts
  • 7. mudstone sandstone limestone Spreads parallel to the bedding planes of the rocks, hence concordant in nature.
  • 9. LACCOLITHS: It is a concordant body, with flat bottom and convex upward. It is dome shaped. When viscous magma is injected rapidly along the bedding, as it cannot spreads it pushes up the overlying layers and keep on piling up. It causes folding of the overlying rock layers.
  • 10. Figure 4-26. Shapes of two concordant plutons. a. Laccoliths with flat floor and arched roof. b. Lopolith intruded into a structural basin. The scale is not the same for these two plutons, a lopolith is generally much larger. Structures and Field Relationships
  • 11. BYSMALITH: It is cylindrically shaped body. • It is developed when highly viscous magma is injected, because the lateral spreading along the bedding is less it acquires to move upwards and form cylindrical shape. • Causes breaking of overlying rock layers.
  • 12. • Their side sloping away from each other which makes them larger and large downwards extending to greater depth • It may be occur discordant and concordant forms of igneous rocks • The irregular masses appears on the batholiths are called stocks and circulars masses are bosses • Their occurrence is commonly associated with the mountain- building process • These are either granites or granodiorites in composition BATHOLITHS: are the largest kind of plutons, irregular in shape and occupies large area.
  • 13. Stocks: Are smaller irregular bodies with 10 km in maximum dimension, and are associated with batholiths.
  • 14. PHACOLITHS: These are concordant bodies that occurs along the crests and troughs of the folded sedimentary strata. LOPOLITHS: These are basin or saucer-shaped concordant bodies with top nearly flat and convex bottom • They are very huge body with diameter upto 150 miles (app. 240 km) Lopolith
  • 15. CHONOLITHS: This term is applied to all other intrusive igneous bodies with irregular shape, i.e. the body with no specific shape.
  • 16. VOLCANIC NECK or VOLCANIC PLUGS: It is cylindrical conduit that fed magma upward to a volcanic vent or it is a conduit of the ancient volcano. Vary in diameter from a few 100s of m to a kilometer or more. These are filled up with crystalline rocks. Shape-circular, elliptical or irregular.
  • 17. TEXTURES OF IGNEOUS ROCKS • Texture is defined as the overall appearance of a rock based on size, shape and arrangement of interlocking minerals • Texture depends on their • (a) Granularity (b) Crystalanity ( C) Shape of crystals • Based on granularity or grain size: Grain size depends on physical conditions that prevailed during the time of Crystallization of magma i.e. presence of volatiles, rate of cooling, pressure, temperature etc. Slow cooling = larger mineral grains Fast cooling = smaller mineral grains
  • 18. PHANERIC TEXTURE Is characterized by LARGE SIZE MINERALS which can be easily seen by Naked eye (size at least 2mm or greater) Coarse-grained Phaneric - > 5mm Medium-grained Phaneric - 1 mm - 5mm Fine-grained Aphanitic <1 mm
  • 19. Commonly associated with the INTRUSIVE (PLUTONIC) IGNEOUS ROCKS, because magma in the crust cools at slower rate and have enough time to result into large mineral grains. Eg. Granite; Pegmatite
  • 22. APHANITIC TEXTURE Is characterized by FINE GRAINED MINERALS, which can be seen under microscope (size < 1mm) Commonly associated with the VOLCANIC (EXTRUSIVE) IGNEOUS ROCKS, because magma on the surface flows cools faster. Eg. Basalts; Rhyolite
  • 25. Based on crystalanity or definite shape: • Crystals are bodies bounded by surfaces, having definite shape by the internal arrangement of atoms i.e. Solidification of minerals from the gaseous or liquid states or from solutions Crystalanity grouped into three types based upon the shape of crystals formation they are Holo Crystalline : A rock composed of mostly crystals Hemi crystalline : A rock composed of partly crystals and glassy Holo hyaline : A rock composed of completely glassy matter
  • 26. Based on Shape of the crystals • The pattern or fabric of a rock depends on the shape as well as relative size and arrangement of the minerals. The shape of the mineral grains in igneous rocks may be broadly grouped into three types Euhedral : Minerals are developed equally in size and shape and are completely bound with faces Sub hedral : Minerals are developed partially or to an intermediate state Anhedral Minerals are developed irregular shapes because their growth is controlled by neighboring materials
  • 27. This happens when slow cooling is followed by rapid cooling. Phenocrysts = larger crystals, matrix or groundmass = smaller crystals ]PORPHYRITIC TEXTURE Is a distinctive mixture of large and fine grained mineral grains
  • 28. ANDESITE PROPHYERY Phenocrysts of Amphibole Ground mass mainly of Plagioclase feldspar (Na/Ca)