Mineralogical and Geochemical Constraints on the Petrogenesis of Post-collisional Potassic and Ultrapotassic Rocks from Western Yunnan, SW China

Paleogene mafic potassic and ultrapotassic volcanic rocks in western Yunnan, China, show a compositional spectrum from potassic trachybasalt to latite (MgO = 6·24–21·8 wt %; SiO2 = 44·5–59·1 wt %). These rocks have high K2O (3·07–5·28 wt %), relatively low Na2O (0·99–4·18 wt %) and high K2O/Na2O ratios (0·91–3·89). They share geochemical features such as depletion of Ta, Nb and Ti relative to other similarly incompatible elements and enriched...