A plate-kinematic model for the assembly of the Bohemian Massif constrained by structural relationships around granitoid plutons
Abstrakt
This paper summarizes the current knowledge on the nature, kinematics and timing of movement along major tectonic boundaries in the Bohemian Massif and demonstrates how the Variscan plutonism and deformation evolved in space and time. Four main episodes are recognized: (1) Late Devonian-early Carboniferous subduction and continental underthrusting of the Saxothuringian Unit beneath the Teplá-Barrandian Unit resulted in the orogen-perpendicular shortening and growth of an inboard magmatic arc during c. 354-346 Ma; (2) the subduction-driven shortening was replaced by collapse of the Teplá-Barrandian upper crust, exhumation of the high-grade (Moldanubian) core of the orogen at c. 346-337 Ma and by dextral strike-slip along orogen-perpendicular NW-SE shear zones; (3) following closure of a Rhenohercynian Ocean basin, the Brunia microplate was underthrust beneath the eastern flank of the Saxothuringian/Teplá-Barrandian/Moldanubian 'assemblage'; this process commenced at c. 346 Ma in the NE and ceased at c. 335 Ma in the SW; and (4) late readjustments within the amalgamated Bohemian Massif included crustal exhumation and mainly S-type granite plutonism along the edge of the Brunia indentor at c. 330-327 Ma, and peripheral tectonothermal activity driven by strike-slip faulting and possibly mantle delamination around the consolidated Bohemian Massif's interior until late Carboniferous-earliest Permian times.