Long-Lasting (65 Ma) Regionally Contrasting Late- to Post-Orogenic Variscan Mantle-derived Potassic Magmatism in the Bohemian Massif Luka ´  sKrmı´ cek 1,2,3 *, Rolf L. Romer 4 , Martin J. Timmerman 5 , Jaromı ´r Ulrych 1 , Johannes Glodny 4 , Antonı ´n P  richystal 3 and Masafumi Sudo 5 1 Institute of Geology of the Czech Academy of Sciences, Rozvojova ´ 269, CZ-165 02 Prague 6, Czech Republic; 2 Brno University of Technology, Faculty of Civil Engineering, AdMaS Centre, Veve  rı ´ 95, CZ-602 00 Brno, Czech Republic; 3 Department of Geological Sciences, Faculty of Science, Masaryk University, Kotla ´ rska ´ 2, CZ-611 37 Brno, Czech Republic; 4 GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam, Germany; 5 Institut fu ¨ r Geowissenschaften, Universita ¨ t Potsdam, Karl-Liebknecht-Strasse 24, Haus 27, 14476 Potsdam, Germany *Corresponding author. Telephone: þ420 233 087 241. Fax: þ420 220 922 670. E-mail: lukas.krmicek@gmail.com Received 17 August 2019; Accepted 1 July 2020 ABSTRACT The orogenic development after the continental collision between Laurussia and Gondwana, led to two contrasting associations of mantle-derived magmatic rocks on the territory of the Bohemian Massif: (i) a 340–310 Ma lamprophyre-lamproite orogenic association; and (ii) a 300–275 Ma lamprophyre association of anorogenic affinity. Major types of potassic mantle-derived magmatic rocks recognized in the orogenic and anorogenic associations include: (i) calc-alkaline to alkaline lamprophyres; (ii) alkaline ‘orthopyroxene minettes’ and geochemically related rocks grouped here under the new term lampyrite; and (iii) peralkaline lamproites. These three types significantly differ with respect to mineral, whole-rock and Sr–Nd–Pb–Li isotope composition and spatial distribution. The calc-alkaline lamprophyres occur throughout the entire Saxo-Thuringian and Moldanubian zones, whereas the different types of malte-derived potassic rocks are spatially restricted to particu- lar zones. Rocks of the Carboniferous lamprophyre-lamproite orogenic association are character- ized by variable negative eNd (i) and variably radiogenic Sr (i) , whereas the rocks of the Permian lamprophyre association of anorogenic affinity are characterized by positive eNd (i) and relatively young depleted-mantle Nd-model ages reflecting increasing input from upwelling asthenospheric mantle. The small variation in the Pb isotopic composition of post-collisional potassic mantle- derived magmatic rocks (of both the orogenic and anorogenic series) implies that the Pb budget of the mantle beneath the Bohemian Massif is dominated by the same crust-derived material, which itself may include material derived from several sources. The source rocks of ‘orthopyroxene mine- ttes’ are characterized by isotopically light (‘eclogitic’) Li and strongly radiogenic (crustal) Sr and may have been metasomatized by high-pressure fluids along the edge of a subduction zone. In contrast, the strongly Al 2 O 3 and CaO depleted mantle source of the lamproites is characterized by isotopically heavy Li and high SiO 2 and extreme K 2 O contents. This mantle source may have been metasomatized predominantly by melts. The mantle source of the lamprophyres may have under- gone metasomatism by both fluids and melts. Key words: 40 Ar/ 39 Ar age determination; mantle melts; mantle metasomatism; lamprophyres; lampyrites; lamproites; Sr–Nd–Pb–Li isotopes V C The Author(s) 2020. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com 1 J OURNAL OF P ETROLOGY Journal of Petrology, 2020, Vol. 61, No. 7: egaa072 doi: 10.1093/petrology/egaa072 Advance Access Publication Date: 10 July 2020 Original Article Downloaded from https://academic.oup.com/petrology/article/61/7/egaa072/5869807 by guest on 01 November 2023