Magnetic fabrics of the NE part of the Central Bohemian Plutonic Complex

BÁRTA, Ondřej and Rostislav MELICHAR. Magnetic fabrics of the NE part of the Central Bohemian Plutonic Complex. In 13th Meeting of the Central European Tectonic Studies Group. 2015. ISBN 978-80-7075-880-9.

Basic information

• Original name: Magnetic fabrics of the NE part of the Central Bohemian Plutonic Complex
• Name in Czech: Magnetická stavba severovýchodní části středočeského plutonického komplexu
• Authors: BÁRTA, Ondřej and Rostislav MELICHAR.
• Edition: 13th Meeting of the Central European Tectonic Studies Group, 2015.

Other information

• Original language: English
• Type of outcome: Conference abstract
• Field of Study: 10500 1.5. Earth and related environmental sciences
• Country of publisher: Czech Republic
• Confidentiality degree: is not subject to a state or trade secret
• Organization unit: Faculty of Science
• ISBN: 978-80-7075-880-9
• Keywords in English: AMS; Benešov type; tectonics movements

Abstract

The study is focused on the NE margin of the Central Bohemian Plutonic Complex, Bohemian Massif, Czech Republic. Plutonic rocks from this area are known as “Benešov type” and they are usually represented by amphibole-biotite granodiorites. Over 350 samples were taken using a portable drill at 26 sampling sites covering almost all study area. AMS (Anisotropy of magnetic susceptibility) data were used to characterize the magnetic fabric. These results were compared with mesoscopic structural observations and, at some sites, also with microstructures. The AMS method showed several different magnetic fabrics and variations in the shapes of the AMS ellipsoid and the magnetic fabric intensity in the area. The degree of anisotropy varies from 1,033 to 1,132. The shape parameter T varies from medium prolate (-0,483) to strongly oblate (0,777). Most of samples have prolate ellipsoid of deformation. The value of shape parameter increases from east to west. Relatively low bulk magnetic susceptibility of measured samples (0,67x10-4SI – 4,08x10-4SI) suggests that the AMS signal is caused by paramagnetic minerals. Magnetic fabrics (Figure 1) are usually homogenously oriented through the Benešov type. Magnetic lineations dip to the NW or N at low angels. Most of magnetic foliations dip to the W. AMS fabric in the Benešov type can be interpreted as deformation fabric of orogenic collapse.