Litho-stratigraphic effect on Variscan fluid flow within the Prague synform, Barrandian: Evidence based on C, O, Sr isotopes and fluid inclusions
| Authors | |
|---|---|
| Year of publication | 2012 |
| Type | Article in Periodical |
| Magazine / Source | Marine and Petroleum Geology |
| MU Faculty or unit | |
| Citation | |
| Doi | http://dx.doi.org/10.1016/j.marpetgeo.2012.01.003 |
| Field | Geology and mineralogy |
| Keywords | Bohemian Massif; Palaeozoic; Variscan orogeny; veins; fluid inclusions; stable isotopes |
| Description | The Palaeozoic sedimentary sequence of the Prague synform (Ordovician- Devonian) in the centre of the Bohemian massif underwent Variscan deformation and thermal overprint events. Variscan veins widespread throughout the sedimentary strata have precipitated from syntectonic aqueous and hydrocarbon-rich fluids. Homogenization temperatures of aqueous inclusions increased from 70 up to 226 degC in the Cambrian rocks underlying the Prague synform. Seawater, modified due to intensive water-rock interaction, was the main fluid component. Fluid flow was limited and restricted to the lithostratigraphic compartments forming a rock-buffered system. Stable isotopic modelling (C, O) and final interpretations of the confined hydrostratigraphic fluid migration was supported by the 87Sr/86Sr ratio in veins and wall rocks. Siliciclastic Cambrian and Ordovician rocks and the associated intersecting veins yielded similar isotopic signatures, and consequently the fluid migration is restricted to layer- and formation-scales. Gradually downwards increasing fluid temperature and compositional changes reflect burial at oil-window conditions. An open fluid system could be expected in proximity of major faults of the Prague syncline and at the top of the sedimentary sequence. |
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