Paleo-Mesoarchean magmatism and sedimentation in the northern part of the Singhbhum Craton: Evidence from zircon U-Pb-Hf, apatite U-Pb, and trace elements

Abstract

Archean cratons are windows into Earth’s early history. The Singhbhum Craton of India preserves an extensive record of Archean magmatism and basin formation events. This study explores magmatism and source-to-sink relationships of the basin in the northern margin of the craton. Magmatic zircon and apatite U-Pb ages from basement granite indicate a mean crystallization age of 3257 ± 19 Ma, with zircon ɛHf(t) values ranging from –2.1 to +1.7 demonstrating the role of crustal melting in magma genesis. Petrographic observations confirm a K-rich composition for this granite. The new data supports correlation of pluton formation to the later phases of the Singhbhum Granite Complex that dominates the craton’s exposure. The unconformably overlying Bisrampur Formation accumulated in a terrestrial environment. Detrital zircon U-Pb ages from the formation include unimodal age distributions between 3412 and 3300 Ma, and their ɛHf(t) values range from –1 to +3.4, with the majority (93 %) of grains having positive ɛHf(t) values. The maximum depositional age of the Bisrampur Formation is indicated by the concordia age of 3073 ± 12 Ma calculated from the three youngest zircon ages with similar ɛHf(t) values (+2.6 to +3.3). Detrital apatite ages overlap detrital zircon ages from each sample and include unimodal age fractions between 3450 and 3300 Ma. Detrital apatite trace elements suggest high- and low-grade metamorphic rocks and minor I-type granitoids and mafic igneous rocks in the source region. The new provenance data from the Bisrampur Formation, combined with previous lithofacies and paleocurrent analyses, demonstrate that these terrigenous strata were sourced from the Singhbhum hinterland and deposited during the Mesoarchean. Correlating the Bisrampur formation to other terrigenous successions in the Singhbhum Craton with well-constrained depositional ages, supports previous hypotheses of craton-wide emersion during the Mesoarchean.