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

Abstract

Abstract:The maar-diatreme volcanic structure in the vicinity of the village of Lomnice near the town of Bruntál (North Moravia, Czech Republic) has been investigated using a set of geophysical methods including ground magnetometry, gravimetry and electrical resistivity tomography. The structure was detected by an aerial magnetic survey in the second half of the 20 th century. Since its discovery only limited information about this buried structure has been available. The coherence of the magnetic anomaly of 190 nT and Bouguer anomaly of -4.7 mGal indicates a volcanic origin of the structure. The funnel-shaped maar-diatreme structure is filled with lacustrine clay and colluvium of Carboniferous greywacke, which forms the country rock. The surface diameter of the structure is about 600 m, the depth is more than 400 m. The spatial association with other volcanic centers in the surroundings of the town of Bruntál infers the relative dating of the Lomnice maar. The phreatic eruption and maar-diatreme formation could be an indirect consequence of effusive activity of the nearby Velký Roudný volcano. The Lomnice structure is the first Plio-Pleistocene maar-diatreme ever described in North Moravia and Silesia.

Introductory Chapter: Updates in Volcanology – From Volcano Modeling to Volcano Geology

“…Volcano gravimetry has developed dramatically in recent years and became a fundamental tool to understand activity changes inside a volcano and hence use collected in situ or near real-time data to estimate volcanic alert status in active volcanoes [24][25][26][27][28][29]. Gravimetry studies also been used to detect various volcanic structures such as maar-diatreme volcanoes and establish the geological origin of sediment field terrestrial basins, which indeed not as simple process as we might think [30][31][32][33]. Similarly, gravimetry has been applied successfully to describe the internal architecture of large volcanoes [34] as well as relatively small-scale features as cavities in lava flows [35].…”