Palaeostress analysis based on multiple inversion in 9-dimensional space in relation to hydrothermal calcite veins in the SE margin of the Elbe Fault Zone (Bohemian Cretaceous Basin, the Czech Republic)
Abstrakt
Palaeostress analysis based on multiple inversion of fault-slip data in 9-dimensional space in the area of the SE margin of the Elbe Fault Zone (E part of the Bohemian Cretaceous Basin, the Czech Republic) reflects five palaeostress phases. Formation of syntectonic calcite veins mostly took place at 500-1000 m depth.
Homogenisation temperature of fluid inclusions (~80 °C) and only subtle variations in fluid salinity point to syntectonic calcite vein formation from a single fluid source and one-step crystallisation. Fluid trapping occurred at 82-84 °C and 4.84-9.67 MPa.
Both oxygen isotope composition of the fluid (δ(18)O(fluid) = 2 promile V-SMOW) and fluid salinity (~3 wt. % eq. NaCl) reflect formation of calcite veins from formation waters expelled from the Cretaceous strata.
Compressional phase D1 (σ1 trending ~N-S) is documented in a regime of reverse faults and strike-slip faults which indicate Europe-Africa coupling and N-directed thrusting of the Alps in the Palaeogene-Early Oligocene. Extensional phase D2 (σ3 generally trending N-S to NE-SW) is indicated by the formation of oblique to normal faults and accompanied by volcanic intrusions in the Middle Oligocene-Early Miocene.
Palaeostress phase D3 (σ1 trending ~NE-SW) reflects Early Miocene compression in the Eastern Alps. Palaeostress phase D4 (σ3 in the direction WNW-ESE) is a result of crustal extension in the Eastern Alps and the Western Carpathians.
Compressional palaeostress phase D5 (σ1 generally trending NW-SE to WNW-ESE) is evidenced by reverse faults and strike-slip faults from the Pliocene. (C) 2021 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.
