Geochemical, Sr-Nd-Pb, and Zircon Hf-O Isotopic Compositions of Eocene-Oligocene Shoshonitic and Potassic Adakite-like Felsic Intrusions in Western Yunnan, SW China: Petrogenesis and Tectonic Implications

Coeval potassic adakite-like and shoshonitic felsic intrusions in the western Yunnan province of SW China are spatially and temporally associated with Eocene–Oligocene shoshonitic mafic volcanic rocks. The shoshonitic syenite and quartz monzonite intrusions are characterized by high K2O contents (4·9–6·8 wt %) and K2O/Na2O ratios (1·1–1·7), high Y (1·7–34·8 ppm) and Yb (1·50–3·16 ppm) contents, nearly flat heavy rare earth element (HREE)...