High-resolution 40Ar/39Ar geochronology of volcanic rocks from the Siebengebirge (Central Germany)—Implications for eruption timescales and petrogenetic evolution of intraplate volcanic fields

Two distinct age groups of melilitites, foidites, and basanites from the southern Central European Volcanic Province reflect lithospheric heterogeneity

“…Basanites, alkaline basalts, and tholeiites formed throughout the Oligocene and the early Miocene in Lusatia (Eger Graben; ~ 35-27 Ma), the Siebengebirge (~ 31-22 Ma), the Westerwald (~ 25 Ma), the Rhön (24-18 Ma), and the Vogelsberg (~ 17-14 Ma), occasionally associated with latites, trachytes, and phonolites without a clear chronological sequence (Abratis et al 2007;Bogaard et al 2001;Büchner et al 2015;Kolb et al 2012;Linthout et al 2009;Mayer et al 2014;Mertz et al 2007;Przybyla et al 2018). Trachytic tuffs are also reported for the Wetterau in the northernmost Cenozoic successions of the URG (~ 26 Ma; Neuhaus 2010).…”

“…gm groundmass, WR wholerock, am amphibole, phl phlogopite, sa sanidine, bt biotite, czt calzirtite, zrl zirconolite ◂ Pfänder et al 2018), and sometimes with age gaps as in the Eifel (Lustrino and Wilson 2007). In other regions, primitive rocks follow more differentiated ones, in turn succeeding primitive rocks (Büchner et al 2015;Przybyla et al 2018;Ulrych et al 2011Ulrych et al , 2013Ulrych et al , 2016. Such compositional sequences have been attributed to pre-, syn-, and post-rift stages (e.g., Eger Graben; Ulrych et al 2011), differentiation due to magmatic plumbing systems (e.g., Siebengebirge; Przybyla et al 2018), and/or different sources and depths of melt generation (e.g., Heldburg region, Kaiserstuhl, Eger Graben; Braunger et al 2018;Ghobadi et al 2021;Pfänder et al 2018;Ulrych et al 2016).…”

“…In other regions, primitive rocks follow more differentiated ones, in turn succeeding primitive rocks (Büchner et al 2015;Przybyla et al 2018;Ulrych et al 2011Ulrych et al , 2013Ulrych et al , 2016. Such compositional sequences have been attributed to pre-, syn-, and post-rift stages (e.g., Eger Graben; Ulrych et al 2011), differentiation due to magmatic plumbing systems (e.g., Siebengebirge; Przybyla et al 2018), and/or different sources and depths of melt generation (e.g., Heldburg region, Kaiserstuhl, Eger Graben; Braunger et al 2018;Ghobadi et al 2021;Pfänder et al 2018;Ulrych et al 2016). Likewise in the southern CEVP, the high temporal, spatial, and compositional variability of the individual regions on the one hand, and the compositional similarities of coeval occurrences on the other hand, refer to heterogeneities in the sub-lithospheric mantle beneath Central Europe (Puziewicz et al 2020).…”

“…Likewise in the southern CEVP, the high temporal, spatial, and compositional variability of the individual regions on the one hand, and the compositional similarities of coeval occurrences on the other hand, refer to heterogeneities in the sub-lithospheric mantle beneath Central Europe (Puziewicz et al 2020). The temporal trend for primitive rocks in the southern CEVP from melilite-free nephelinitic-basanitic rocks to melilitebearing olivine nephelinites and olivine melilitites may indicate decreasing partial melting degrees, greater formation depths, a thicker lithosphere, a more carbonate-accentuated source, and/or a reduced influence of assimilation and fractional crystallization for the latter (e.g., Bogaard and Wörner Abratis et al 2007;Aziz et al 2010;Büchner et al 2015;Fekiacova et al 2007;Ghobadi et al 2021;Gregor 2003;Harangi et al 2010;Harangi et al 2015;Hurai et al 2013;Keller et al 2002;Koban and Schweigert 1993;Kraml et al 1995Kraml et al , 1999Kraml et al 2006;Lenz et al 2015;Lexa et al 2010;Linthout et al 2009;Lukács et al 2018;Lutz et al 2013;Mayer et al 2014;Mertz et al 2000;Mertz et al 2007;Mertz et al 2015;Molnár et al 2019;Nowell et al 2006;Pfänder et al 2018;Przybyla et al 2018;Rasser et al 2013;Riisager et al 2000;Schleicher et al 1990;Schmitt 2006a;Schmitt et al 2007;Schubert et al 2015;…”

“…In the northern part of the CEVP, numerous occurrences of volcanic rocks have been dated by modern 40 Ar/ 39 Ar techniques (e.g., Abratis et al 2007;Büchner et al 2015;Linthout et al 2009;Mayer et al 2014;Mertz et al 2000Mertz et al , 2007Mertz et al , 2015Pfänder et al 2018;Przybyla et al 2018;Schubert et al 2015;Shaw et al 2010;Singer et al 2008;van den Bogaard 1995). In the southern CEVP, however, modern geochronological studies are rare (Fekiacova et al 2007;Keller et al 2002;Schmitt et al 2007) and precise ages for many regions and individual localities in the southern CEVP are still lacking and existing ages mostly represent old K-Ar whole-rock data (Baranyi et al 1976;Horn et al 1972;Lippolt et al 1963Lippolt et al , 1973Lippolt et al , 1975Lippolt 1983), which have been shown to be erroneous or at least imprecise in several cases (e.g., Baranyi et al 1976;Keller et al 2002;Lippolt et al 1963).…”