Chronological implications of the paleomagnetic record of the Late Cenozoic volcanic activity along the Moravia-Silesia border (NE Bohemian Massif)

Abstract

This paper presents the results of a paleomagnetic study carried out on Plio-Pleistocene Cenozoic basalts from the NE part of the Bohemian Massif. Paleomagnetic data were supplemented by 27 newly obtained K/Ar age determinations. Lavas and volcaniclastics from 6 volcanoes were sampled. The declination and inclination values of paleomagnetic vectors vary in the ranges of 130 to 174 and -85 to -68° for reversed polarity (Pleistocene); or 345 to 350° and around 62°f or normal polarity (Pliocene). Volcanological evaluation and compilation of older geophysical data from field survey served as the basis for the interpretation of these results. The Pleistocene volcanic stage consists of two volcanic phases, fairly closely spaced in time. Four volcanoes constitute the Bruntál Volcanic Field; two others are located 20 km to the E and 65 km to the NW, respectively. The volcanoes are defined as monogenetic ones, producing scoria cones and lavas. Exceptionally, the largest volcano shows a possibility of remobilization during the youngest volcanic phase, suggested by paleomagnetic properties. The oldest one (4.3-3.3 Ma), Břidličná Volcano, was simultaneously active with the Lutynia Volcano (Poland) which produced the Zálesí lava relic (normal polarity). Three other volcanoes of the volcanic field are younger and reversely polarized. The Velký Roudný Volcano was active during the Gelasian (2.6-2.1 Ma) and possibly could have been reactivated during the youngest (Calabrian, 1.8-1.1 Ma) phase which gave birth to the Venušina sopka and Uhlířský vrch volcanoes. The reliability of all available K-Ar data was evaluated using a multidisciplinary approach.

Mesozoic and Cenozoic evolution of the Central European lithosphere

“…15, Blusztain and Hart, 1989Ladenberger et al, 2004;Badura et al, 2005), and Moravia (No. 16, Cajz et al, 2012;Ulrych et al, 2013). Some smaller volcanic fields are located separately in SW Germany: Kaiserstuhl (No.…”

Identification of a Buried Late Cenozoic Maar-Diatreme Structure (North Moravia, Czech Republic)

“…The initiation of the eruption, which created the maar-diatreme structure, can thereby be related to the activity of the nearby-located Velký Roudný volcano. Several effusive phases were documented based on radiometric dating (Table 2), with at least two main episodes (Cajz et al 2012).…”

“…The inner volcanic group in the surroundings of the town of Bruntál comprises several types of volcanic structures, including the Velký Roudný scoria cone with associated lava flows (Cajz et al 2012), the feeder vent in Břidličná or the Razová subaquatic tuffs (Barth 1977;Cajz et al 2012). The effusive rocks are mostly represented by olivine basalt, nephelinite basanite and olivine nephelinite (Barth 1977).…”

Evidences of interactions between Velký Roudný volcanic activity and its hydrous environments

“…Evidences of interactions between Velký Roudný volcanic activity and its hydrous environments (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31) Výskyty kenozoických vulkanitů v oblasti Nízkého Jeseníku sice patří co do objemu vulkanických hornin k těm méně významným oblastem, na druhou stranu jde o jedny z nejmladších projevů vulkanické aktivity Českého masivu. Erupce mafických alkalických magmat zde probíhaly během pozdního pliocénu (piacenz) a pleistocénu (gelas-calabr; Cajz et al 2012). Právě díky nízkému stáří bruntálského vulkanického pole, jak je tato oblast výskytů označována (Cajz et al 2012), jsou zde dobře zachované povrchové pyroklastické facie, ale také originální povrchové formy.…”

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Velký Roudný scoria cone represents the most prominent volcanic edifice of the Plio-Pleistocene Bruntál Volcanic Field (according to Cajz et al 2012). Various types of volcaniclastic deposits and volcanic features were interpreted in various ways in the past.

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