%0 Journal Article %T Variable origin of clinopyroxene megacrysts carried by Cenozoic volcanic rocks from the eastern limb of Central European Volcanic Province (SE Germany and SW Poland) %+ Géosciences Environnement Toulouse (GET) %A Matusiak-Małek, Magdalena %A Puziewicz, Jacek %A Ntaflos, Theodoros %A Woodland, Alan %A Uenver-Thiele, Laura %A Büchner, Jörg %A Grégoire, Michel %A Aulbach, Sonja %< avec comité de lecture %J Lithos %V 382 %8 2021 %D 2021 %Z 2021Litho.38205936M %R 10.1016/j.lithos.2020.105936 %Z Sciences of the Universe [physics]Journal articles %X Clinopyroxene megacrysts occurring in Cenozoic mafic alkaline volcanic rocks from the northern margin of the Bohemian Massif (SW Poland, SE Germany) could be subdivided by colour and Mg# (Mg/(Mg + Fetot)) in three groups. Megacryst with the highest Mg# = 90.0-91.5 ("high Mg#", HMg#) is transparent and strongly Light Rare Earth Element (LREE) depleted and contains abundant orthopyroxene lamellae. The clinopyroxene megacrysts with "medium Mg#" (MMg#) values (76.8-83.4) are transparent to light grey and are all LREE-enriched. The group with the lowest Mg# (LMg#; 62.2-74.6) is intensively coloured (from grey to green) and may enclose apatite, Ti-magnetite or pseudomorphs after amphibole. The "low Mg#" (LMg#) clinopyroxenes are LREE-enriched, and some display positive Zr-Hf anomalies.

The single HMg# megacryst records pressures ~1GPa and temperature of 1280 °C, pointing to its mantle origin. It is the first megacryst described in European lavas and possibly worldwide, which shows affinity to Depleted MORB Mantle (DMM). The MMg# megacrysts formed from fractionating mafic magmas at variable pressures and temperatures - from those corresponding to mantle depths (>1 GPa, 1230-1350 °C) to lower/middle crustal values (0.5-0.9 GPa, 1120-1150 °C). The parental melts for this group are isotopically related to the Cenozic volcanic rocks from the study area. The LMg# megacrysts crystallized from strongly alkaline melts, mostly at lower- to middle-crustal pressures (0.4-1.0 GPa). Their parental melts were also related to Cenozoic volcanism, but their strongly evolved nature resulted in local, but significant enrichment in Zr and Hf. The LMg# megacrysts from three localities in Poland are the first evidence of strongly alkaline magmatism in the north-easternmost part of Cenozoic European Volcanic Province. %G English %2 https://insu.hal.science/insu-03661476/document %2 https://insu.hal.science/insu-03661476/file/1-s2.0-S0024493720305715-main.pdf %L insu-03661476 %U https://insu.hal.science/insu-03661476 %~ IRD %~ INSU %~ METEO %~ UNIV-TLSE3 %~ CNRS %~ CNES %~ OMP %~ OMP-LMTG %~ OMP-GET %~ UNIV-UT3 %~ UT3-INP %~ UT3-TOULOUSEINP