Evidence of Neoarchean adakitic alkaline magmatism in the Eastern Dharwar Craton

Archean alkaline magmatism is exceptionally rare in the geological record, offering valuable insights into Archean tectonic processes, mantle evolution, and crustal growth. This study presents in situ titanite U-Pb geochronology, trace element geochemical data, and bulk-rock geochemical results for an adakitic syenite pluton from the Danduvaripalle area of the Eastern Dharwar Craton, southern India. The investigated pegmatoidal leucocratic syenite forms an undeformed, oval-shaped plug with an NNE-SSW orientation, emplaced in a regional extensional to transtensional crustal setting. The syenite is predominantly composed of pure end-members of alkali feldspar, aegirine-augite, diopside, titanite, actinolite, apatite, and magnetite.Bulk-rock geochemical analyses indicate a metaluminous nature, exhibiting highly fractionated REE patterns with marked middle REE depletion, resulting in an overall spoon-shaped REE profile typical of melts affected by high-pressure amphibole and garnet fractionation. The rocks exhibit elevated La/Yb (>45) and Sr/Y (>100) ratios, with pronounced heavy REE depletion (Yb < 0.7 ppm, Y < 8 ppm), which confers a distinct adakitic geochemical signature. Extreme Lu/Gd ratios (