Detrital zircon LA-ICPMS U-Pb and Lu-Hf signature from the Mesoarchean Keonjhar Quartzite: Implications for the nature of Archean continental crust and geodynamics

Abstract

The ∼715 m thick matured siliciclastics of the Keonjhar Quartzite, North of the homonymous town, Singhbhum Craton, eastern India, represents one of the best-preserved examples of sedimentation during Mesoarchean time. The LA-ICPMS U-Pb ages with peaks at 3.2 Ga, 3.1 Ga, 3.0 Ga and 2.87 Ga of the detrital zircon grains from the upper part of the Keonjhar Quartzite reveal youngest age population of ∼2.87 Ga. The Hf isotopic compositions have mean initial 176Hf/177Hf ratio of 0.280897 and low Lu/Hf ratio of 0.01. Most of the grains of the zircon population show positive εHf (+8.75 to +0.26) values with only two negative values of -0.05 and -3.27. The superchondritic Hf isotopic compositions suggest depleted mantle source, juvenile crustal components and possible role of juvenile crust formation presumably in a stagnant lid to low angle subduction geodynamic regime for the origin of granitoids that sourced the detrital zircon grains.

Keywords

• Detrital zircon
• U-Pb and Lu-Hf isotopic signature
• Keonjhar Quartzite
• Singhbhum craton
• Mesoarchean geodynamics