Vindhyan Basin

Vindhyan Basin

Kaimur Sandstone

Vindhyan basin lies in the central part of India. Bundelkhand craton lies in the east and Aravalli-Delhi  fold belt in the west. CITZ lies in the south. 

Vindhyan basin is named after Vindhyan mountains of Madhya Pradesh where they are best developed.

They covers an exposed area of about 60,000 sq km and concealed area of about 1,62,000 sq km under the Deccan traps and Indo-gang. alluvium. 

The thickness of basin is 5-6 km.

The sedimentation was started in mesoproterozoic and continued till mid cambrian.

It has ultramafic pipes containing diamonds. 

Structure 

The basin is mostly undisturbed and unmetamorphosed.

Great Boundary Fault is present on western margin which brought Vindhyans against Aravalli. The throw of this fault is ~1500 m.

The basin has shape of large flat syncline.

Stratigraphy

Succession of Vindhyan has been divided into 2 parts; lower and upper Vindhyan. Lower Vindhyan is consisted of only Semri group while Upper Vindhyans have Kaimur, Rewa and Bhander groups.

Lower Vindhyan

Semri group represents the lower Vindhyan.

It overlies the Bijawar group, and seperated by basal conglomerates. Lowest unit is Khairagarh limestone.   

Khairagarh limestone is overlain by Porcellinite formation. It is equivalent to Malani rhyolites suit of Rajasthan.

Next is Kheinjua formation, it has stromatolites. Their age is controversial but agrees on ~1260 million years.  

Rohtas formation contains Suket shales and Nimbahera limestone. 

Depositional environment

Marine environment was dominant. Calcarious rocks and stromatolites show the presence of shelf enviornment.

Upper Vindhyan

Upper Vindhyan overlies Semri group with well marked unconformity of red jasper pebbles at Son valley and Dhar forest. In other places, it directly overlies the Bijawar rocks.

Rewa group has diamond containing ultramafic pipes.

Upper Bhander sandstone are reddish in colour.

Depositional environment

Fluvial processes were dominated. Evidences are unidirectional ripple marks and other structures. Red colour of upper Bhander sandstone indicates arid conditions.

Ripple marks in Kaimur sandsone.

Economic value

• Panna mines, Majhgawan in Madhya Pradesh have diamond deposits.
• Bijaigarh shale have beds of pyrite but are not of much economic value.
• Sandstone mining is done in Bhander group.