4. BASTAR CRATON
• Bastar craton covers an area of 1,30,000
• It is bounded by the Godavari Graben in the
• Mahanadi graben in the north-east.
• CITZ (central Indian tectonic zone) forming
part of the Satpura mobile belt in the north.
• Eastern Ghats mobile belt in the east and
Daccan trap cover in the west.
5. The important lithotectonic
association in the craton :
• Gneissic complex (Sukma,Amgoan), with granites of
different ages(Dongargarh, Malajkhnad, Kanker, Jharim,
• Granulite belts ( Bhopalpatnam, Kondagaon)
• Kotri –Dongargarh orogen.
• Isolated fold belts of Bengpal, Sakoli and Sonakhan
• Mafic dyke Swarms (Bijapur, Gidam, Kondagaon,
• Proterozoic ‘purana’ basins ( Abujhmar, chattisgarh,
Khariar, Indravati, Pranhita-Godavari etc.
6. Generalised stratigraphy of Bastar craton
Kotri-Dongargarh orogen Rest of craton
1800-2000Ma chilpi Group 1800-2000Ma Chilpi group=sakoli group
~2300 Dongergarh Granite ~2300 Malajkhand granite
~2300Ma Nandgaon Group
~2400Ma Bailadila Group
2300Ma Sonakhan group
2500-2600Ma Bengpal Group 2500-2600Ma Bengpal group
~3000Ma Amgaon group
2600Ma Bhopalpatnam and kondagaon
granulites, sukma granites
~3000Ma Sukma group
> 3000Ma gneissic Complex with vestiges of 3500-3600 Ma events
7. DESCRIPTION OF STRATIGRAPHY
• Sukma group
large swaths and widespread enclaves of
supracrustal within the TTG gneisses are the
oldest suites of the craton called the Sukma
group.sukma is also exposed prominently in the
south and east of Bailadila hills,near
Gidam,Dantewara,Bijapur and Pakhanjur,and as
scattered enclaves up to Dongargarh Granite.
8. Lithology of Sukma Group
TTG gneisses (~3.0Ga)
Banded iron formation(BIF)
Amphibolites and ultramafics
Diopside calc-silicate rocks and
Basement unknown (but may be 3.5Ga gneissic)
9. STRUCTURE AND METAMORPHISM:
• Structure in sukma group are complex, as the
rock are scattered. Major folds are found in
• Metamorphism is of low-pressure type.
• AGE : Rb-Sr isochron ages of 2500-2600 Ma
3500-3600Ma determined by U-Pb and
SHRIMP zircon. The age of sukma group is rekoned
at ~3000 Ma.
10. AMGAON GROUP
• Amgaon Group occurs in a ~100 km wide belt to
the south of sakoli belt around Gadchiroli, where
sukma type lithologies occure within migmatites
and grade into granulites in the NW extensions of
Bhopalpatnam granulite belt.
• The amgaon enclaves consist of quartzite, calc
silicate rocks, marbles, chromoferous ulteramafic
and subordinate BIF.
• Amgoan group of enclaves is marked by
• AGE : The age of amgaon group is uncertain..
11. GRANULITE BELTS
• Bhopalpatnam granulite belt(Bh):
• Bh is about 300km long and 30-40km wide,
and trend NW-SE to the north of godavari
graben,corresponding to the Karimnagar granulite belt of
dharwar craton in the south.
• Kondagaon granulite belt(Kg):
• Kn granulite belt is a 70 km long, NS
trending belt occuring to the north of Indravati basin. It
appears to be an uplifted horst like structure.
• The Kg granulite belt indicates ages arround
13. BENGPAL GROUP
• Bengpal group occure in a synclinorium
plunging SSE that extend from Bailadila to
Tulsi Dongar hills close to the Eastern ghat
mobile belt. The lithology of bengpal group is
Andalusite .phyllite and schist and
Quartz-sericite schist and sericite
14. STRUCTURE OF BENGPAL GROUP
• Bengpal group invovled in complex isoclinal to
reclined folding. Bengpal belt appears to form
a regional synclinorium plunging towards
• Most of the dates are Rb-Sr isochrones of
15. KOTRI DONGARGARH OROGEN
• BAILADILA GROUP-
• Bailadila Hills, representing the type area for
BaildilaGroup, form the southernmost part of
the Kotri- Dongargarh orogen..
• The iron ore deposite extend from the north
of Bailadila to Rowghat and Dalli-Rajhara that
contribute iron ores to the Bhilai Steel Plant .
16. Bailadila Group
Banded iron formation
Chloritic and sericite
phyllites with local
interbeds of polymict
conglomarete and minor
bands of mafic-
17. NANDGAON GROUP
• Bailadila Group is uncomformably overlain by a
sequence of bimodal felsic to mafic volcanics
belonging to Nandgaon Group that is well
exposed between Dongargah Granite and
• Nandgaon group is not extensively deformed ,
but N-S trending fold and fault are fairly common.
The Rhyolites of Nandgaon group yield Rb-Sr
whole rock isochron ages of ~2300 Ma.
19. KHAIRAGARH GROUP
• The Sandstone –Basalt alternations of Khairagarh
group overlie the Nandgaon group and Dongargarh
Granite. It is separates from the Nandgaon Group by an
eruptive unconformity marked by Dongargarh Granite.
• The age of this Group is uncertain.
• Lithology- Ghogra SST
• Mangikhuta Basalt
• Karutola SST
Khairagarh Group Sitagota Basalt
• Bortalao SST
20. CHILPI GROUP
• The predominently low Grade metasediments
of chilpi group are well exposed in the type
area of chilpi ghatsection on the Chilpi-
Bilaspur road. The main rock unit of the group
are chloritic and sricite phyllites and banded
• The age of chilpi group is not known with
certainty, it may be >1800 Ma old, by
comparision with Sakoli and Khairagarh Group
21. SAKOLI GROUP
• Sakoli Group covering an area of 3500 square km
, is a triangular belt, which occurs at the three
major tectonic trend lines viz. The satpura mobile
belt, kotri-dongargarh belt, and parallel to tha
• The triangular outcrop pattern of sakoli and
sauser belt was described in earlier litrature as
• The rock assemlage of the belt is metapelites
with subordinate felsic to mafic bimodal
22. LITHOLOGY OF SAKOLI GROUP
Pawani Formation Slate, phullite,arkose, quartz-
arenite and conglomarete
Bhiwapur Formation Mainly metapelites
Dhabetekri Formation Mainly metabasalts,with minor
Gaikhuri Formation Conglomarete ,coarse
arenite,minor pelites and BIF
Amgaon Gneiss and Supracrustals
23. SONAKHAN GROUP
• The Isolated ,NW-Trending Sonakhan belt
covering an area of 1000 square km. since the
Sonakhan belt is predominently a volcanic belt,
• It has been termed as schist belt or greenstone
• Arjuni Formation
• Baghmara Formation/Bilari