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Povzetek: In this study, we focused on the Pliocene–Early Pleistocene fluvial terraces in the Velenje Basin andreconstructed the morphostratigraphy, sedimentary depositional environment, provenance and age of the graveldeposits using geomorphological, sedimentological, petrographic and chronological analyses. Geomorphologicalmapping revealed the presence of two main river‐terrace groups. The terraces in the older terrace group are severelydegraded and preserved only as remnants capping high ground, while in contrast the younger group is betterpreserved. Detailed lithofacies analyses of four selected stratigraphic sections of the older terrace group show that thegravel was deposited in a meandering and wandering environment. The gravel consists of metamorphic, igneous,volcaniclastic, clastic and carbonate lithologies derived from the north, east and west from the Paka Rivercatchments. To determine the timing of deposition, we performed isochron‐burial dating using cosmogenic 26Al and10 Be. Our new age constraints date the deposition of the older terrace group to 2.7 ± 0.3 Ma. Establishing theaggradation and incision model of the Velenje Basin documents pronounced regional tectonic uplift during thePliocene–Early Pleistocene, which led to incision and the subsequent formation of a terrace staircase.
Ključne besede: isochron‐burial dating, morphostratigraphy, provenance analysis, river terraces, Velenje Basin
Objavljeno v DiRROS: 05.09.2024; Ogledov: 106; Prenosov: 47
Celotno besedilo (7,81 MB)

Povzetek: In the southernmost outcrops of the Slovenian Basin the Middle Jurassic coarse-grained limestone breccia (mega)beds are interstratified within a succession that is otherwise dominated by hemipelagites and distal turbidites. In this paper, these beds are described as the Ponikve Breccia Member of the Tolmin Formation. We provide descriptions of the studied sections with detailed geological maps and analysis of the breccia lithoclasts. From the latter, a non-outcropping margin of the Dinaric Carbonate Platform is reconstructed. In the Late Triassic the platform margin was characterized by a Dachstein-type marginal reef. After the end-Triassic extinction event, the platform architecture remained, but the reefs were replaced by sand shoals characterized by ooids. In the late Early Jurassic and/or early Middle Jurassic a slope area might have been dissected by normal faults and a step-like paleotopography was formed. In the Bajocian, during a period of major regional geodynamic perturbations, extensional or transtensional tectonic activity intensified and triggered the large-scale collapses of the Dinaric Carbonate Platform margin producing the limestone breccias described herein. This may in turn have caused a backstepping of the platform margin, as is evident from the occurrence of Late Jurassic marginal reefs that are installed directly above the Upper Triassic and Lower Jurassic inner platform successions.
Ključne besede: Slovenian Basin, Dinaric Carbonate Platform, Middle Jurassic, limestone breccia, debris-flow, stratigraphy, Ponikve breccia
Objavljeno v DiRROS: 18.01.2023; Ogledov: 805; Prenosov: 546
Celotno besedilo (24,45 MB)
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