|
|
Assembly of the Saxothuringian orogenic wedge: the Variscan P-T-t record of the metasediments of Erzgebirge, Bohemian Massif
Jouvent, Marine ; Lexa, Ondrej (advisor) ; Tichomirowa, Marion (referee) ; Pitra, Pavel (referee)
The formation of collisional orogenic wedges involves complex polyphase deformation and metamorphism. This study reveals the tectonic evolution, internal architecture and the timing of the Variscan orogenic wedge evolution in the Saxothuringian Domain (Bohemian Massif). The studied area is the Erzgebirge Crystalline Complex, characterized by numerous occurrences of the (U)HP rocks. In contrast, the surrounding metasediments have been scarcely studied, although they provide an important link between deep subduction and mid-crustal processes. Using field structural geology, petrology, thermodynamic modelling and geochronology (monazite U-Pb and mica 40 Ar/39 Ar dating), we constrained the P-T conditions and timing of four deformation events (D1-D4) identified by structural analysis. Several transects from the low-grade hanging wall phyllites to the footwall medium-grade micaschists have been investigated. The first M1-D1 event is characterized by HP-LT minerals (garnet, chloritoid, phengite, paragonite, and rutile) defining the S1 foliation with an M1 peak pressure conditions increasing from 13 kbar and 520řC in phyllites to 25 kbar and 560řC in micaschists. The corresponding geothermal gradient of 6-11řC/km is typical for subduction environments. The M2-D2 event corresponds to the deformation and...
|
guest ::
