Eastern dharwar craton

1. SEMINAR
ON
EASTERN DHARWAR CRATON

2. C0NTENTS
 INTRODUCTION
 DHARWAR CRATON
 EASTERN DHARWAR CRATON
 STRATIGRAPHY OF EDC
 GREENSTONE BELTS OF DHARWAR SUPERGROUP
 CLOSEPET GRANITE
 VERTICAL ZONATION OF THE CLOSEPET GRANITE
 REGIONAL METAMORPHISM
 CONCLUSION
 REFERENCE

3. INTRODUCTION
 A large portion of a continental plate that has been
relatively undisturbed since the Precambrian era and
includes both shield and platform layers.
 The word craton was first proposed by
the German geologist L. Kober in 1921 as "Kratogen",
referring to stable continental platforms.
 There are five Craton in Indian shield:-
Dharwar Craton
Bastar Ctaton
Singhbhum Craton
Aravalli craton
Bundelkhand Craton

4. TECTONIC MAP OF INDIAN SHIELD

5. DHARWAR CRATON
 Archean Dharwar Craton covers a total area of 4.5 lakh
sq.kms.
 Bounded by Pan-African Pandyan Mobile belt (PMB)
towards the south, Cretaceous Deccan traps towards
the north, Proterozoic (Purana) Kaladgi and Bhima
basins, Neoproterozoic Eastern Ghats mobile belt
towards (EGMB) toward east, Arabian sea towards the
west and Archean Karimnagar granulite belt (KGM)
toward north east
 It consists of the greenstone schists belts, charnokites,
grey gneiss,quarzite, marble, BIF, and the younger
granites.
 Divided into Eastern and Western Dharwar Craton
seperated by the Chitradurga Shear Zone.

7. STRATIGRAPHY

8. CLASSIFICATION OF EDC
 The component units are:
 OLDER GNEISS: Older gneiss are not widespread in
EDC, isolated U-Pb Zircon dates of over 3000 Ma are
seen in some gneissic outcrops along the Western and
Eastern margin of Greenstone belts like Kolar and the
Ramagiri. (Putative basement).
 WARANGAL GROUP: Lithologies mainly belong to
quartzite–pelite-carbonate consisting of fuchsite
quartzite, quartz pebble conglomerate, calc silicates,
marble , cordierite -anthophyllite rocks, BIF.
o These suites are similar to that of Sargur Group but for the
lesser development of mafic and ultramafic suites ,it is
named as Warangal Group.
o Run parallel trends to those of Dharwar schist belts having
similar metamorphic and migmatic history.

9. GREENSTONE BELTS OF DHARWAR SUPERGROUP
 EDC is characterised by volcanics-dominated,
sediment-impoverised and gold rich greenstone belts,
in contrast of WDC.
 The greenstone belts are engulfed all sides by younger
granatoids.
 The Yeswantanagar Formation of the Sandur belts has
similarity to that of Bababuddan Group intruded by
granite.
 Most of the greenstone belts are corelatable with that
of the Chitradurga belt of WDC.
 The greenstone belts of EDC form linear arrays and
are called superbelts or composite belts-extends
underneath the cuddapah Basin .

11. IMPORTANT GREENSTONE SUPERBELTS OF EDC :
 Ramagiri (Penakachela-Sirigeri)-Hungund
superbelt:-
Ramagiri-Penekacherla-Sirigeri Greenstone Belt,
Hundgund Greenstone Belt
 Kolar-Kadiri-Jonnagiri-Hutti superbelt:-
Kolar Greenstone Belt,Kadiri Greenstone Belt,
Jonnagiri Greenstone Belt, Hutti Greenstone Belt
 Veligallu-Raichur-Gadwal superbelt:-
Veligallu Greenstone Belt, Raichur Greenstone Belt,
Gadwal Greenstone Belt,
 Sandur superbelt

12. Hutti Greenstone belt
 Rich in gold mineralisation called as Hutti Maski belt
with southern extension to Siruguppaa
 Cover an area of about 670 km2 consist of basic
volcanic suite, minor BIF in basic acidic volcanics,
greywackes and polymict, granite-clast conglomerate.
 The Hutti-Maski belt has a NNW-SSE trend with a
sharp hook shaped bend in the north towards SE.
 The hook shape of the belt can be attributed to cross
folds and also to the diapiric nature of the two phases
of granatiod intrusions into the greenstone belt.

14. Kolar Greenstone Belt
 Narrow linear schist belt intruded by diapric granites
of Patna and Bisanattam, and by granodioritic gneisses
on all sides.
 It consists of amphibolites, BIF, cordierite-silliminite-
fuchsite quarzites, calc-sillicate rocks, manganiferous
chert and carbonate.
 The overlying pillowed, agglomeratic and variolitic
amphibolites are essentially tholeiites.

15. INDEX
1. mafic rock
2. volcanoclastic
sediments
(champion gneiss)
3. Banded
ferruginous chert
4. granite and gneiss
5. granitic pluton
Geological sketch map of Kolar Schist belt

16. CLOSEPET GRANITE
 It is a unique linear body consisting of diverse granitic
types.
 The granites have easterly convexity that mirrors the
configuration of the schist belts.
 Named after the town of Closepet, named for Major
Close, a British Army officer and now known as
Ramanagaram.
 It is 200 km long and 20-30 km wide plutonic belt
bounded by shear zones
 High precision Zircon ages of granite from different
laboratories define a narrow age of 2510-2530 Ma.
 It is divisible into two parts-southern and the northern
separated near Kalyandurga by a Gap area.
 The closepet granite is divided in to 3 depth zones 1.Root
Zone, 2.Transfer Zone, 3.Intrusion Zone with a gap
zone.

17. VERTICAL ZONATION OF THE CLOSEPET GRANITE

18. REGIONAL METAMORPHISM
 It is of low-pressure facies series with typical pelitic
assemblages of andalusite-cordierite-staurolite in
amphibolite facies grading into cordierite-garnet-
silliminite-hypersthene in granulite facies.
 Metamorphic P-T conditions of EDC range from
670˚C/3kb in Sandur belt in the north, through
710̊C/4-5 kb in the middle to 750̊C/6-7kb in
Krishnagiri-Dharmapuri area.
 Low pressure metamorphism of EDC is caused by the
abundance of younger granite providing the advective
heat, which was lack in WDC.

19. CONCLUSION
 Dharwar Craton is a classical greenstone-granite
terrain, divided into Western and Eastern Dharwar
Craton.
 It is separated by the Chitradurga Shear Zone close to
the Closepet Granite.
 EDC consists of the older gneisses, greenstone belts of
Dharwar super group, Closepet Granite and
charnokites.
 It is one of the best studied terrain of Peninsular India.
 EDC is regarded as an Archean batholith that accreted
on to the craton in the west along a diffuse zone of
interaction

20. REFERENCE
 Geology of India by M.Ramakrishnan and R. Vaidyanathan.
Published by Geological Society of India: Vol.I, 2008 page:
48-50, 99-180
 WEB:
www.google.com:-
www.mindat.org/loc-49196.html
wikipedia.org/wiki/Dharwar_Craton