Upper Cretaceous to Pleistocene melilitic volcanic rocks of the Bohemian Massif: petrology and mineral chemistry

Abstract

ratios (0.7033-0.7049) point to an additional late-to post-magmatic hydrothermal contribution. Major rock-forming minerals include forsterite, diopside, melilite, nepheline, sodalite group minerals, phlogopite, Cr-and Ti-bearing spinels. Crystallization pressures and temperatures of clinopyroxene vary widely between ~1 to 2 GPa and between 1000 to 1200 °C, respectively. Nepheline crystallized at about 500 to 770 °C. Geochemical and isotopic similarities of these rocks occurring from the Upper Cretaceous to Pleistocene suggest that they had similar mantle sources and similar processes of magma development by partial melting of a heterogeneous carbonatized mantle source.

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

“…3). However, while several studies on the petrogenesis of such rocks exist for the northern part of the CEVP (e.g., Duda and Schmincke 1985;Harmon et al 1987;Jung et al 2006;Pfänder et al 2018;Skála et al 2015;Ulrych et al 2008Ulrych et al , 2011Ulrych et al , 2013Ulrych et al , 2016, similar occurrences in the southern CEVP have been much less investigated (Blusztajn and Hegner 2002;Dunworth and Wilson 1998;Hegner et al 1995;Hegner and Vennemann 1997) and comparative work involves SiO 2 -saturated, basaltic and evolved rocks (e.g., Fig. 3 TAS diagram for the investigated rocks in the southern CEVP.…”

“…Some of them comprise large-scale lava sheets or pyroclastic deposits, while others consist of accumulations of vents, stocks, or dykes. The volcanic products investigated in the studied area (Table 1) comprise basalts, basanites, tephrites, latites, trachytes, phonolites, nephelinites, haüynites, melilitites, and carbonatites (e.g., Abratis et al 2009;Bogaard and Wörner 2003;Braunger et al 2018;Büchner et al 2015;Dunworth and Wilson 1998;Jung and Hoernes 2000;Jung et al 2005Jung et al , 2006Jung et al , 2011Kolb et al 2012;Kramm and Wedepohl 1990;Schubert et al 2015;Skála et al 2015;Ulrych et al 2016;Wörner et al 1986).…”

Exploring Causal Relationships for Geoheritage Interpretation — Variable Effects of Cenozoic Volcanism in Central European Sedimentary Tablelands

“…Subsequent brittle deformations of the crust, involving also the near-surface sedimentary packages, resulted in the origin (or reactivation) of numerous deep-seated faults, used by magma to ascend towards the contemporaneous Earth surface. In some cases, fault zones were filled by long, but narrow (a few metres at most) subvolcanic dykes (Skála et al 2015). The most famous example of such phenomenon is the 20 km long, SW-NE trending Čertova zed' (Devil's Wall) to the east of Ralsko Geopark, which is a part of a larger dyke swarm.…”

“…However, the site is not at all developed and dense vegetation makes it almost inaccessible during the plant growth season. • Čertova zed' (Czechia) -the name was given to a nearly 20-km-long basaltic dyke that cuts through the host sandstone (Janoška 2013;Skála et al 2015). According to oral tradition, the dyke used to stand out as a rock wall up to 10 m high over most of its length, but many sections were completely quarried away as a valuable stone resource.…”

40Ar/39Ar step-heating dating of phlogopite and kaersutite megacrysts from the Železná hůrka (Eisenbühl) Pleistocene scoria cone, Czech Republic

“…The Železná hůrka cinder cone is composed of scoriaceous hauyne-bearing olivine melilitite (Ulrych et al 2013;Skála et al 2015). Hradecký (1994) recognized three, 2.5 to 8 m thick sequences composed of ca.…”