INTRUSIVE IGNEOUS ROCKS

Содержание

1. INTRUSIVE IGNEOUS ROCKS
2. FORMS OF INTRUSIVE IGNEOUS ROCKSCommonly observed forms
3. DYKES: Dykes and sills are the most
4. Quartz-Dolerite dykes of Midland valley of Scotland
5. eg. Lamprophyric rocks broadly represented by kimberlites.
6. SILLS: Sills are relatively thin tabular sheetlike
7. Spreads parallel to the bedding planes of the rocks, hence concordant in nature.
8. LACCOLITHS: It is a concordant body, with
9. BYSMALITH: It is cylindrically shaped body.It is
10. Their side sloping away from each other
11. Stocks: Are smaller irregular bodies with 10
12. PHACOLITHS: These are concordant bodies that occurs
13. CHONOLITHS: This term is applied to all
14. VOLCANIC NECK or VOLCANIC PLUGS: It is
15. TEXTURES OF IGNEOUS ROCKSBased on granularity or
16. PHANERIC TEXTUREIs characterized by LARGE SIZE MINERALS
17. Commonly associated with the INTRUSIVE (PLUTONIC) IGNEOUS
18. DIORITE
19. GABBRO
20. APHANITIC TEXTUREIs characterized by FINE GRAINED MINERALS,
21. BasaltRhyolite
22. Obsidian
23. This happens when slow cooling is followed
24. ANDESITE PORPHYRYPhenocrysts of AmphiboleGround mass mainly ofPlagioclase feldspar (Na/Ca)
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FORMS OF INTRUSIVE IGNEOUS ROCKSCommonly 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

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Слайд 1INTRUSIVE IGNEOUS ROCKS

Слайд 2FORMS 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.

FORMS OF INTRUSIVE IGNEOUS ROCKSCommonly observed forms of Plutonic (intrusive) rocks observed in the field are: dykes,

Слайд 3DYKES: 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

DYKES: Dykes and sills are the most common forms of the intrusive igneous bodies.They are discordantCut across

Слайд 4Quartz-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.

Quartz-Dolerite dykes of Midland valley of Scotland are about 50-60 km long and upto 30m thick. Few

Слайд 5eg. 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.

eg. Lamprophyric rocks broadly represented by kimberlites. Lamprophyre dykes are located close to the western and eastern

Слайд 6SILLS: 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

SILLS: Sills are relatively thin tabular sheetlike body that penetrates parallel to the bedding planes.Laterally it may

Слайд 7Spreads parallel to the bedding planes of the rocks, hence

concordant in nature.

Слайд 8LACCOLITHS: 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.

LACCOLITHS: It is a concordant body, with flat bottom and convex upward. It is dome shaped.When viscous

Слайд 9BYSMALITH: 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.

BYSMALITH: It is cylindrically shaped body.It is developed when highly viscous magma is injected, because the lateral

Слайд 10Their side sloping away from each other which makes them

larger and large downwards extending to greater depth

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.

Their side sloping away from each other which makes them larger and large downwards extending to greater

Слайд 11Stocks: Are smaller irregular bodies with 10 km in maximum

dimension, and are associated with batholiths.

Слайд 12PHACOLITHS: 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

Слайд 13CHONOLITHS: This term is applied to all other intrusive igneous

bodies with irregular shape, i.e. the body with no specific

shape.

Слайд 14VOLCANIC 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.