Geochemical study of Ambaji − Sendra granitoids and mafic dykes from the South Delhi fold belt, NW Indian shield: Implications for magma generation, emplacement and geodynamic evolution

Abstract

This study presents a comprehensive account of geochemical data on the granitoids of Ambaji-Sendra Terrain and associated mafic dykes. These granitoids, interpreted as S–type, I-type and A-type, lack a consensual interpretation probably due to the study of only those rocks which are exposed in Sendra region. We identified that these granitoids are A-type (A2- subtype) granites. There are two petrogenetic groups of the granitoids having exclusive crustal and crust-mantle interactive origins which are supported by their mineralogy and structure. The associated dykes also display two distinct geochemical groups one with within-plate character and other with typical arc signatures. Whole body of evidence suggests that magma for the granitoids and dykes was generated during the closure of Delhi Ocean. The simultaneous emplacement of granitoids started during subduction process and culminated after the collision or/ accretion of Delhi arc with eastern crustal block, consequent to the Rodinian assembly mechanism.

Keywords

• South Delhi Fold belt
• Aravalli craton
• NW Indian shield
• Rodinia connection