Publication details
Late Pleistocenne fluvial sedimentation in the Upper Morava pull-apart basin: Stratigraphy, facial analysis and sediment provenance patterns
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| Year of publication | 2015 |
| Type | Appeared in Conference without Proceedings |
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| Description | Upper Morava Basin (UMB) is a syndepositional pull-apart basin developed at the contact of the Bohemian Massiff with the Outer Western Carphatians and drained by the Morava River and its tributaries. UMB is a 90 km long and 30 km wide graben-like depression controled by NW - SE striking fault of the Elbe-Odra zone. Tectonic activity of these faults strongly influenced the basin fill stratigraphy and structure, surface morphology and rapid switching between sources areas of its siliciclastic sediments. The basin is filled by Upper Miocene/Lower Pliocene to Pleistocene/Holocene lacustrine and fluvial sediments with maximum thickness localy exceeding 300 m. Differential tectonic uplift and subsidience in the UMB is documented in the variable depths of erosion of the preQuaternary basement as well as the relative height of terrace systems, which are preserved on the slopes of adjacent elevations and beneath the active rivers flood-plains. Stratigraphy, depositional environmental and provenance patterns of the UMB were studied from lithofacial analysis, grain-size distribution, petrophysical patterns, clast composition, heavy-mineral spectra and bulk-rock and single grain geochemistry. Four wells were drilled and several hundred-m-scale outcrops in sand pits and river banks were studied. The studied fluvial sediments are mostly coarse-grained and poorly sorted facies Gt, Gh, Gmg and Gmm (Miall 2006) forming a sedimentary bodies with thickness up to 10 meters. These sandy gravels alternated with more-fined grained sands of the facies classes Fsn, Fm, Fl and Sh. Petrophysical patterns (mass specific magnetic susceptibility, sediment colour) and element geochemistry in drill cores make it posible to observe three distinct fluvial phases. Heavy mineral data and clast composition indicate that these phases were sourced from different source areas, mostly located in the NE part of the Bohemian Massiff. OSL and 14C dating (ages from Early Saalian to Holocene) suggests that differential subsidience played an importent role in the infill of the basin. |