Deciphering the Late Paleozoic to Mesozoic tectono sedimentary evolution of the northern Bohemian Massif from detrital zircon geochronology and heavy mineral provenance
Abstrakt
From Permian to Late Cretaceous, the northern Bohemian Massif experienced a complex intra-plate tectono sedimentary evolution involving development of at least four generations of sedimentary basins in different settings. We examine this protracted evolution using stratigraphic changes in sediment provenance, analyzed through heavy mineral assemblages and U-Pb detrital zircon geochronology (by laser-ablation ICP-MS) in Permian, Jurassic, and Late Cretaceous successions.
The provenance data point to multiple, temporally evolving sources ranging from local (e.g., the 'West Sudetic Island & apos;) through more distant from elsewhere in the Bohemian Massif to exotic, likely derived from Baltica. The latter is interpreted as a trace of now completely eroded Late Jurassic to Early Cretaceous basin that once covered the Lusatian (Lausitz) Block and received the Baltica-derived detritus from northerly fluvial and deltaic depositional systems.
We suggest that fill of this basin was recycled into the Bohemian Cretaceous Basin during progressive unroofing of the West Sudetic Island. A time-slice reconstruction of the paleogeographic and tectono sedimentary evolution of the northern Bohemian Massif is then developed to show that periods of basin development and deposition (early Permian, late early Permian to Early Triassic, Middle Jurassic-Early Cretaceous, and Late Cretaceous) were interrupted by major depositional gaps (Middle Triassic-Early Jurassic, mid-Cretaceous, and post-early Campanian).
The Mesozoic depositional episodes resulted from reactivation of major NW-SE strike-slip fault zones due to stress transfer from the North Atlantic Rift during Jurassic to Early Cretaceous, overridden by the far-field effect of convergence of Iberia, Africa, and Europe during Late Cretaceous.