• First zircon age constraint on the Pichhore orbicular granitoid. • Giant orbicules with diverse morphologies and multi-shelled structures. • U–Pb zircon dating indicates a 2.56 Ga crystallization age. • Zircon reveal ∼3.5 Ga crustal reworking linked to Neoarchean magmatic activity. • Sm–Nd isotopes support anatectic origin from ancient crustal sources. We present the first U–Pb zircon geochronology and comprehensive geochemical analysis of a rare orbicular granite from Pichhore, Bundelkhand Craton, India. This previously undated rock unit is exposed over a small area of approximately 0.0012 km². The granite exhibits remarkable features, including large orbicules (up to 30 cm in diameter) with diverse morphologies, such as circular, elliptical, single- and multi-shelled structured composed of coarse-grained quartz, plagioclase, K-feldspar, muscovite, and biotite. U–Pb zircon dating reveals three age populations: inherited grains at 3495 ± 16 Ma, 3488 ± 20 Ma, and 3295 ± 14 Ma, reflecting older TTG sources, and a discordia upper-intercept age of 2565 ± 42 Ma interpreted as the crystallization age. Whole-rock Nd isotopes (εNd(t) = −3.25) indicate significant reworking of Paleoarchean crust. Geochemical data (SiO 2 : 71.68–74.77 wt%; Al 2 O 3 : 13.40–15.46 wt%; K 2 O: 5.68–8.05 wt%) and consistent plagioclase compositions suggest orbicule formation through single-stage crystallization from a water-rich, high-K granite melt under fluid-saturated conditions. The 2.56 Ga age correlates with the peak Neoarchean granitoid magmatism and regional crust stabilization, underscoring prolonged crustal recycling in a dynamic continental margin.
No takes yet. Share an insight, caveat, or question.
Singh et al. (2026) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: