The Role of Magma Mixing in the Petrogenesis of Eocene Ultrapotassic Lavas, Western Yunnan, SW China

Abstract Magma mixing is a widespread magmagenic process. However, its significance in the formation of ultrapotassic magmas has been largely overlooked so far as they are commonly thought to originate directly from mantle and ascend rapidly through crust. The Hezhong lavas Western Yunnan (SW China) (basaltic) trachy-andesitic composition. These rocks display porphyritic textures with olivine, clinopyroxene (Cpx), spinel, phlogopite occurring both phenocryst glomerocryst. Disequilibrium complex zonation crystals observed. Specifically, based on textural compositional characteristics, olivines can be classified into three different populations: two populations characterized by highly moderately magnesian normal chemical core-rim (Fo~94–86 Fo~89–79 Fo~91–89 Fo~86–84, respectively). third population lacks obvious crystal zonation, but individual exhibit some variety at lower Fo contents (Fo83–76). Similarly, four Cpx spinel phenocrysts recognized terms texture Notably, reverse zoning contains ‘green-core’ surrounded colourless rim. Hence, variations mineral assemblage, types inclusions, compositions, all phenocryst/glomerocryst minerals divided groups. Mineral Group I (MG I) consists high cores zoned phlogopite. MG II only includes green reversed (green-core Cpx), III composed micro without rims large phenocrysts. Comparing these groups relevant typical temporally spatially associated igneous rocks, we suggest that could have derived compositions resembling an olivine lamproite trachyte, respectively. overall bulk-rock geochemical isotopic features also agree process between endmembers. infer played key role petrogenesis crystallized mixed magmas. Our study highlights inferring caution must taken when using bulk magma deduce source signatures.