Petrogenesis and geological significance of rhyolitic volcanic rocks from the Ningyuancun formation in eastern Songnen block

The Mesozoic volcanic successions in the eastern Songnen Block provide critical constraints on regional tectonic evolution and crustal growth processes, owing to their diagnostic geochemical signatures. This study addresses a research gap by investigating the Ningyuancun Formation rhyolites through integrated petrographic and whole-rock geochemical analyses (major/trace elements), aiming to delineate their petrogenetic mechanisms, magma provenance, and geodynamic setting. These rhyolitic volcanics display characteristic I-type granitoid affinities: peraluminous high-K calc-alkaline compositions with elevated SiO 2 and alkali contents, moderate Mg-Fe ratios. These rocks display low ΣREE, LREE-enriched chondrite-normalized patterns with HREE depletion and weak Eu anomalies. Negative SiO 2 correlations with Al 2 O 3 -MgO–TiO 2 –CaO–TFeO–P 2 O 5 in Harker diagrams, coupled with Sr-Rb/Sr, Sr-Ba, and La-(La/Yb)N covariations, indicate fractional crystallization of amphibole, ilmenite, apatite, feldspar. Bulk compositions confirm derivation from partial melting of evolved continental crust, while regional syntheses constrain emplacement to an active continental margin regime during westward subduction of the Mudanjiang slab beneath the Songnen Block.