Zpravodaj Hnědé uhlí 2019, 59(2)
Indications of two unknown maar-diatreme volcanoes of Quaternary age near Libá in western Bohemia by gravity survey
In the year 2014, we have identified two crater formations in the morphology of the terrain resembling volcanic structure of maar/diatreme at the Ztracený rybník nature reserve. They are located northwest of Cheb in the western Bohemia on the territory formed by the Smrčiny/Fichtelgebirge granite massif. In the same year we have carried out gravity survey on the profiles as well as at random points according to the accessibility of the terrain. Measurements were difficult especially at the bottom of the larger crater of Ztracený rybník due to the swampy surface, which is very unstable for gravimetric measurement. After the data processing we produced the gravimetric map, which showed two very significant negative anomalies correlating with the bottoms of the craters. The negative amplitudes of the anomalies were in excess of -3 mGal for the larger crater of Ztracený rybník and -2 mGal in the smaller structure. The accordance between gravity feature and geomorphology was very similar to the Mýtina Maar that was confirmed by exploration drill in 2007. Due to the relatively sharp shaped morphology of both craters, we assume that they are Quaternary structures.
Keywords: maar, volcanic structure, gravity survey, West Bohemia
Published: June 1, 2019 Show citation