EMPLACEMENT CONDITIONS OF THE VOLCANIC COMPLEX AT RADOBÝL, CZECH REPUBLIK

Abstract:

The volcanic complex at Radobýl is of unknown provenance and the construction mechanism(s) remain elusive. No determination has yet been made of how this volcanic complex was emplaced or how it fits in with the wider regional volcanic systems. The hypotheses are: 1) if the complex represents a nested sequence of intrusions, it is not known where the feeder source for those rocks is located; 2) if the complex represents a stacked sequence of extrusive lava flows, then there is no obvious source vent within the complex for the lava flows to have been sourced; the vent could be many kilometers away. It is also suspected that there are multiple layers of lava flows or intrusive events within the complex. This research investigates, using paleomagnetic and petrological methods, how the volcanic complex was emplaced. Using multiple core samples taken from the separate suspected layers of lava various petrological, paleomagnetic, and related tests are being run to try and determine direction of flow and relative ages of the suspected layers. Paleomagnetic data is used to try and provide the relative ages of the suspected lava flow layers (using secular variation of Earths' magnetic field), sub-volcanic deformations, and the timing duration of those flows. The rock magnetic variations are examined using hysteresis, curie point analysis (CP), alternating field demagnetization curves, and Iron-Titanium Oxide compositions of the core samples. Flow fabrics are examined using Anisotropy of Magnetic Susceptibility (AMS). Petrology (using thin sections) informs on compositional variations, grain sizes, and some aspects of the chemical makeup of the samples. Ground magnetics help define the ‘Intrusion’ geometry, polarity intensity, and thickness. This complex forms a landmark within the local landscape that is of historic and cultural significance and this study will help give the local population more information on the formation of this site.