Neoproterozoic Tectonics of the Kaliguman Shear Zone: Implications for the Delhi-Aravalli Fold Belt Contact, NW India

The Kaliguman Shear Zone (KSZ) in northwestern India marks the boundary between the South Delhi Fold Belt to the west and the Aravalli Fold Belt to the east. Structural analysis reveals a narrow, high-strain zone characterized by the development of mica schist along this boundary. The principal structural orientation trends in the NE-SW direction. Strain analysis indicates that the rocks in this zone formed under transpressional deformation conditions.

The metamorphic history of the KSZ is well-preserved in the mica schists, which predominantly contain garnet and staurolite. Petrological and textural studies have helped establish the relative crystallization sequence of mineral phases during the metamorphic events. Examination of garnet porphyroblasts reveals a complex deformation pattern, reflecting pre-, syn-, and post-tectonic events associated with fabric formation. Geothermobarometric analysis indicates that the mica schists underwent amphibolite facies metamorphism. Phase equilibria analysis, supported by PT pseudosections, shows peak metamorphic conditions at approximately 590±10 °C and 4.7 kbar. Garnet isopleth plots suggest increasing pressure and temperature during metamorphism, which is consistent with the inferred PT path. Variations in the modal abundance of index minerals further corroborate this evolutionary trajectory. These findings support a model of crustal thickening for the KSZ. The textural control monazite age data from the mica schists confirms that the shear zone was formed during the early Neoproterozoic. The study provides valuable insights into the tectonic evolution of the contact between the Delhi and Aravalli Fold Belts, highlighting the role of shear zones in accommodating deformation and facilitating metamorphic processes during Neoproterozoic orogenic events.

Keywords: Kaliguman Shear Zone, Aravalli, Delhi Fold Belt, Neoproterozoic, NW India