Publication details

Magnetic and Structural Studies of Křivoklát-Rokycany Volcanic Complex, Barrandian, Czechia



Year of publication 2017
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description Křivoklát-Rokycany Complex is the largest area of Cambrian volcanic rocks in Barrandian Area. Generally, it consists of two structural levels: 1) Older lower level, where the most abundant rock is andesite, and 2) Younger upper level with lavas of rhyolitic character. The older andesitic structural level lies on the Cambrian sediments of Skryje-Týřovice Basin and below the rhyolitic level. Usually, it is very hard to recognize any visible magmatic lineation or foliation in rocks of the level. For that reason, the AMS fabrics were studied instead. Fortunately, structures representing magma flow as magmatic foliation and bubble prolongation in andesite were observed in few places. These few observations allowed correlation of AMS and real magmatic petrofabric. The magnetic lineation is parallel in all cases to the direction of magma flow. Therefore, the magnetic foliations can be considered as magmatic foliations representing flow surphaces, and magmatic lineation (K1) is direction of magma flow. Rhyolitic rocks in the uppermost structural level forms a lot of topographic elevations and outcroppes, where huge amount of visible flow structures is present. For that reason, the AMS studies did not need to be performed in this level. All the measured magmatic foliations around the elevations are centroclinal with increasing dip angle towards the center. More or less chaotic fluidal structures are usually present at the top of each elevation. Conclusions: 1) The Sýkořice Porphyry is not likely to be main channel for Rhyolitic volcanism in Křivoklát-Rokycany Complex as suggests diamagnetic character of the dyke in comparison with the rhyolites. 2) The AMS fabrics were calibrated with petrofabrics in few sites. Magnetic lineations and foliation coralates with magmatic lineation and foliation. 3) Elevations in the rhyolitic part may be considered as small old volcanic centers.

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