The Delhi Supergroup represents a prominent Proterozoic supracrustal sequence within the Aravalli mountain range of northwestern India, largely exposed in Rajasthan and parts of Haryana. It records a significant chapter of basin evolution, sedimentation, and later deformation.

Lithostratigraphy

In the North Delhi Fold Belt, the succession is broadly divided into three groups:

• Raialo Group: The basal unit dominated by limestones, dolomites, and associated mafic volcanic rocks, reflecting an early rifting stage with shallow marine deposition.
• Alwar Group: Overlying the Raialo, it is dominantly arenaceous, characterized by thick quartzite successions interbedded with schists and volcanic flows, deposited in a high-energy clastic environment.
• Ajabgarh Group: The youngest unit, composed of phyllites, schists, calc-gneisses, and impure marbles with volcanic associations, representing deeper water, quieter depositional conditions.

These groups form linear NE–SW trending belts, collectively termed the Delhi Fold Belt, showing complex polyphase folding and metamorphism.

Distribution

The Supergroup extends for hundreds of kilometers along the Aravalli trend, from Delhi in the northeast through Haryana into Rajasthan. Major exposures occur in the North Delhi Fold Belt (e.g., Alwar basin) and parts of the South Delhi Fold Belt.

Economic Significance

The Delhi Supergroup is an important mineral host.

• Metallic minerals: Copper is notably concentrated in the Ajabgarh and Alwar Groups (e.g., Khetri, Alwar), with minor lead-zinc occurrences.
• Building materials: Quartzites of the Alwar Group and marbles/limestones of the Raialo and Ajabgarh Groups are widely quarried, historically used in architecture.
• Industrial minerals: Localized occurrences of minor industrial minerals are also reported.

Thus, the Delhi Supergroup is both geologically and economically significant, combining insights into Proterozoic tectonics with valuable mineral resources.