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Hrubcová et al. - 2017 - Active magmatic underplating in western Eger Rift, Central Europe

Hrubcová et al. - 2017 - Active magmatic underplating in western Eger Rift, Central Europe

Pavla Hrubcová and Václav Vavryčuk, researchers of the Institute of Geophysics of the Czech Academy of Science, investigated in cooperation with their colleagues active magmatic underplating in western Eger Rift.

The Eger Rift, active element of the European Cenozoic Rift System, is associated with intense Cenozoic intraplate alkaline volcanism and system of sedimentary basins. The intracontinental Cheb Basin at its western part displays geodynamic activity with fluid emanations, persistent seismicity, Cenozoic volcanism, and neotectonic crustal movements at the intersections of major intraplate faults. In this paper, we study detailed geometry of the crust/mantle boundary and its possible origins. Based on seismic data from reflection and refraction profiles and from local seismicity, we identify significant lateral variations of the high-velocity lower crust and relate them to mantle-derived fluids and petrology. The observations point to a local-scale magmatic emplacement at the base of the continental crust within a new rift environment. The concept of magmatic underplating is evidenced by detecting two types of lower crust: a high-velocity lower crust with pronounced reflectivity and a high velocity reflection-free lower crust. The character of the underplated material enables to differentiate timing and tectonic setting of two episodes with different times of origin of underplating events. Spatial and temporal relations to recent geodynamic processes suggest active magmatic underplating in the intracontinental setting.

 


Fig. 1: The interpreted cross section of 9HR reflection profile showing two types of lower crust in west Bohemia at the western edge of the Eger Rift indicating the extent of the late Cenozoic magmatic underplated body at crust-mantle boundary. The blue bars represent the extent of the Cheb Basin (CB) and Mariánské-Lázně (ML) degassing centers at the surface; the red bar represents the extent of seismicity projected at the surface.

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