Delhi Supergroup rocks are exposed in the Aravalli Mountains as a NE-SW trending ling linear belt from Delhi in the north-east through southeastern Haryana and Central Rajasthan to the north-eastern pat of Gujrat in the south-west. These rocks are strongly deformed and metamorphosed, only isolated hills and ridges made up of Delhi rocks. Delhi supergroup of rocks are exposed in two belts North Delhi Fold Belt (NDFB) and South Delhi Fold Belt (SDFB)
The NDFB has been divided into three groups : Raialo, Alwar and Ajabgarh from older to younger respectively.
In the SDFB rocks are consists of mainly two units named as Gogunda Group and Kumbhalgarh Group. Gogunda group is consists of arneceous sequence of uartzite and interbedded schist and metabsic rocks. The Kumbhalgarh Group is consists of pelitic schist, calc-gneiss and impure marble.
Gogunda = Alwar
Kumbhalgarh = Ajabgarh
Raialo Group :-
There is occurence of a sequence of conglomerate and quartzite overlain by basic volcanics and volcanic breccia and tuff. It also contains carbonate rocks.
Alwar Group :-
It is arenaceous facies sequence. Basal part is derived form BGC and made up of granitic rocks. The succession contains several sill-dyke bodies of epidiorite of both intrusive and extrusive nature. The Alwar group in northern are is seen to lie over the Raialo group with an unconformable contact while it is directly over the Aravalli supergroup in the southern area.
Ajabgarh Group :-
The transition beds between the Alwar Group and Ajabgarh Group are represented by calcareous facies in the Alwar area is named as Kushalgarh Limestone. Limestone shows coarse and crystalline character, which is attributed to high-grade metamorphism. There are few horizons of brecciated rocks collectively known as Hornstone breccia.
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