A complex magmatic system beneath the Kissomlyó monogenetic volcano (western Pannonian Basin): evidence from mineral textures, zoning and chemistry

摘要: Abstract Kissomlyo is a small-volume Pliocene alkaline basaltic eruptive centre located in the monogenetic Little Hungarian Plain Volcanic Field (western Pannonian Basin). It consists of sequence pyroclastic and effusive units: early tuff ring (unit1), pillow columnar jointed lava (unit2), spatter cone (unit3). The overlain by unit lacustrine sediments which suggests significant time gap volcanic activity between formation emplacement flow. High-resolution investigation mineral textures, zoning chemistry as well whole-rock geochemical analyses were performed on stratigraphically controlled samples order to characterize magmas represented distinct units reveal evolution deep magmatic system. Based bulk rock geochemistry, compositionally similar erupted surface during entire activity. However, olivine crystals show diverse patterns compositions reflecting various deep-seated processes. Five different types occur samples. Type1 olivines represent phenocryst sensu stricto phases, i.e., crystallised situ from host magma. other evidence for textural compositional disequilibrium single consisting portions having origins. Type2a type2b have antecrystic cores are derived two primitive based their spinel inclusions. Type4 reverse whose low-Fo antecrysts more evolved magmas. type3 type5 xenocrysts originated subcontinental lithospheric mantle. These surrounded high-Fo or growth zones suggesting that xenocryst incorporation occurred at levels stages magma evolution. Olivine-hosted inclusions three groups. Group1 spinels very Al-rich (0–0.22 Cr#) coexist with type2a olivines, group2 44.5–62.3 Cr#s s.s. (type 1) while group3 rich Cr (68.4–81.3 appear olivines. integrated analysis four environments involved into bear petrogenetic processes playing role batches: fractional crystallization, (+ spinel) recycling, incorporation, recharge interaction multiple small packets multi-level Clinopyroxene-melt thermobarometry yields an average pressure 6.6 ± 0.9 kbar corresponding depth about 25 km, implying main level final clinopyroxene fractionation could around Moho (in lowermost crust). This study shows high-resolution mineral-scale carried out through sequences provide unique, detailed insight these “simple” systems crystal stratigraphy yield direct usually obscured geochemistry.