Geochronology and geochemistry of Paleoproterozoic granodiorite in Liujiahe area, eastern Liaoning Province: Geological implication

A large number of granitic rock mass exposed in eastern Liaoning Province serves as a critical medium for investigating the tectonic evolution history of Paleoproterozoic Jiao-Liao-Ji orogenic belt. Through the study of petrology, chronology, and geochemistry of the Paleoproterozoic granodiorites in Liujiahe area of eastern Liaoning Province, this paper determines the genesis and further explore the tectonic attributes of Paleoproterozoic Jiao-Liao-Ji orogenic belt. The study shows that the zircon U-Pb dating of granodiorite yields a weighted mean age of 2 180.7 ± 9.0 Ma, indicating its Paleoproterozoic formation. The SiO₂ content is 66.39%-71.65%(averagely 69.11%), Al₂O₃ 11.35%-15.58% (averagely 12.67%), K₂O+Na₂O 7.22%-9.05%(averagely 7.89%), K₂O/Na₂O 0.53-0.59(averagely 0.55), with high content of CaO (0.65%-4.12%, averagely 2.44%) and MgO (0.16%-0.86%, averagely 0.51%). The sample is of calc-alkaline to high-K (calc-alkaline) series, with A/CNK of 0.63-1.10 and A/NK of 1.06-1.20, belonging to metaluminous-peraluminous rocks, characterized by low REE content, and relatively depletion of HFSEs(Nb, Ta, Ti, Ba), showing the characteristics of I-type granites. The geochemical characteristics indicate that the granodiorite is originated from the partial melting of felsic crust under low-pressure conditions, with distinct island arc magmatic features. In the tectonic discrimination diagram, all samples plot within the volcanic arc granite field, indicating the subduction-induced arc magmatism in Liao-Ji orogeny during early Paleoproterozoic (2.2-2.1 Ga).