Kaladgi and Bhima Basin

Kaladgi Basin

Kaladgi basin is an E-W trending irregular basin It is underlain by the basement

granitoids(Peninsular Gneiss Dharwar Batholith) of the Dharwar Craton in the South and East and underlain by the Deccan Trap in the North

I t covers an area of about 8300 sq kmIt is made of the older Kaladgi sequence and the

younger Badami sequence occuring in separate sub-basinal areas.

It is not spatially associated either with mobile belt or with terrain boundaries and hence it is not marginally deformed.

• Kaladgi basin hosts vast recourses of limestone and dolomite, as well as building and ornamental stones, besides minor iron ore.

BAGALKOT

GROUP

Badami Group(285)

Katageri Limestone (150)Kerur Arenite (135) Angular Unconformity

Limestone, shaleConglomerate,arenite,shale

Intrusives Quartz veins, pegmatites, dolerite dykes

Simikeri Subgroup(1150)

Hosakatti Argillite(700)Arlikatti Dlolmite (130)Niralkerr Breccia (40)Kundargi Quartzite (280) Disconformity

Argillite Dolomite, hematite bedChert BrecciaConglomerate, quartzite, argillite

LokapurSub-group(2750)

Yadahalli Argillite (60)Muddapur dolomite (5650Chikshillikeri Limestone (800)Yargatti Argillitte (720)Mahakut Breccia (130) Saundatti Quartzite (475)

ArgilliteDolomite,Limestone,argilliteLimestone,shaleArgillite,dolomite Chert brecciasConglomerate, quartz, shale

Nonconformity and angular Conformity

Gneisses/Granites and Schist Belts of Dharwar craton

LithologyThe older succession of Kaladgi basin is called the

Bagalkot Group which corresponds to the Cuddapah Supergroup, and the upper succession is called the Badami group.

Bagalkot GroupThe Bagalkot group is divided into :

(1) Lokapur Subgroup and(2) Simikeri Subgroup

Bagalkot Subgroups(1) Lokapur Subgroup :

Yadahalli Argillite (60) Argillite (Purple to Grey)

Muddapur dolomite (565) Stromatolite Dolomite(grey)-topLimestone(grey)-middleArgillite -bottom

Chikshillikeri Limestone (800) Limestone/Dolomite(Naganur)-topThe limestone is variegated and grey coloured and associated with shale and are intricately folded.

Yargatti Argillitte (720) Argillite(grey stromatolitic Dolomite)-topIntercalations of manganiferous shale, hamatite beds and Limestone

Mahakut Breccia (130) Breccia consisting of pink microcrystalline silica with angular fragments of chert and occurs as lenses in Shale

Saundatti Quartzite (475) Conglomerate, Quartzite, Shale

Bagalkot Subgroups(2) Simikeri subgroup

Hosakatti Argillite(Thick highly foloded argillite . Has thin interbeds of hematite and dolomite)

Arlikatti Dolomite(Banded hematite jasper and hematite schists (BIF) underlies the stromatolite dolomite-chert-limestone-argillite unit

Niralkerr Breccia(Massive and oolitic chert (novaculite) and chert breccias)

Kundargi Quartzite(Thick-bedded mature quartzite and purple laminated shale)

Intrusives

Numerous Pegmatites and Quartz veins, and a few Dolerite dykes intrude

the Bagalkot Group.

Badami groupIt is essentially an horizontal to low-dipping

arenaceous succession with minor shale.The basal Kendur conglomerate in Kerur Arenite

overlies the basement granitoids and schists, as well as Bagalkot Group with a major unconformity

The main red sandstone unit forming flat-topped hills contains the famous Badami cave temples

Sedimentary structures such as ripple marks, cross beds, groove casts, parting lineations and convolute laminations abound in this sandstone

Badami GroupKatageri Limestone(150) Consists of a lower chocolate

brown laminated shale with thin siltstone and liomestone interbeds, overlain by an upper variegated flaggy limestone with shale partings.

Kerur Arenite(135) The basal Kendur conglomerate in Kerur Arenite overlies the basement granitoids and schists, as well as Bagalkot Group with a major unconformityThe sandstone is overlain by olive shale and grey sandstone

Sedimentary Environment of Kaladgi BasinBagalkot group commences with deposition along

a transgressive coast, progressively deepening through a tidal flat and shallow shelf, to offshore with abundant carbonates to the plateform

Shale, dolomite, with chert, BIF and manganiferous horizons in the succession suggest quiet shelf to lagoonal environment

Badami Group is essentially a coastal to shallow shelf deposit

Palaeocurrents indicate northwesterly paleoflow for Bagalkot Group and south Westerly paleoflow for Badami Group

Structure of Kaladgi Basin Bagalkot Group occupying the middle of the elongate

basin is characterized by a series of tight to isoclinal, doubly plunging anticlines and synclines with WNW-ESE axial trace, which are locally refolded by N-S trending folds.

Concomitant with deformation, the rocks are metamorphosed, with sandstone becoming quartzite, shale becoming phyllite and micritic carbonate becoming microsparite.

Badami Group with gentle dips shows large amplitude open folds. Major E-W faults cut across the basin at Sirur, Saundatti and B.N. Jalihal.

Life in the Kaladgi BasinRocks of Bagalkot Group are reported to contain

algal mats and acritarchs, besides a variety of Stromatolites.

Presence of microstromatolites such as Yelma digitata suggest early Riphean age for Bagakot Group, which is also supported by isotopic dating of Chitradurga dolomite at 1600-1700 Ma.

Badami Group also contains acritarchs and trace fossils that suggest Vendian age.

Bhima Basin

Bhima Basin The Bhima basin is situated to the northwest of Cuddapah

basin and Northeast of Kaladgi basin It consists dominantly of limestone It covers an area of 5200 sq.km It overlies the granitic basement of Eastern Dharwar

craton with a profound unconformity and has faulted contacts at many places. Deccan Trap overlies Bhima Basin in the North.

The sediments have an aggregate thickness of about 270m

The Basin is well known for its large reserves of Limestone and the newly discovered Uranium occurrence near Gogi.

Lithology of the Bhima BasinBHIMA GROUP

Andola Subgroup (30-70m)

Harwal Shale (5-10m)-The Katamdevarahalli limestone is gradational with the overlying Harwal shale, which marks the top of Andola Subgroup.Katamdevarahalli Limestone (10-40m) –Graduated from the Shales of the Disconformable beds through a sequence of flagstones and siliceous limestonesHalkal Formation (15-20m) -is marked by chert and limestone pebble conglomerate forming the base of Andola subgroup.-----------------------Disconformity--------------------------------

Sedam Subgroup (65-215m)

Shahaabad limestone is flaggy, variegated, and grey, with rare chert interbeds and is used in cement industry .(45-130m)Rabanpalli Formation commences with conglomerate and ‘grit’ beds. The conglomerates consists of clasts of vein quartz, feldspar and tourmaline set in a siliceous matrix and is exposed near Kachaknur and Muddebihal. Arkosic and quartz arenite, siltstone, laminated olive shale and well-exposed purple shale overlie the conglomerate horizon. (20-85m)

Structure and Life of Bhima BasinBhima sediments are practically horizontal, but are

disturbed along transverse faults, the most important one being Gogi where it has cut across the Shahabad Limestone and basement granite, and is marked by limestone breccia and uranium mineralization.

Microbiota and palynofossils are compatible with the Neoproterozoic age of the Bhima Group.