engleski

Carpathian-Badenian facies in the Mt. Medvednica area

In the area of Čučerje, on SE flanks of the Mt. Medvednica, a geological column has been investigated in marine deposits of Carpathian and Lower Badenian age. Carpathian deposits are represented by facies of massive marls with sand interlayers, and deposits of Badenian age by horizontally bedded sands with laminated marls, trough cross-bedded sandstones, horizontally bedded biocalcarenites and biocalcrudites, bioclastic tuffites and tuffs. Marls from the facies of massive marls with sand interlayers were deposited from the suspension in restricted shelf environment, and sands during temporary storm events, when material eroded from shallow environments was transported to shelf by turbulent currents. Depositional mechanism of horizontally bedded sands with laminated marls facies was similar to the aforementioned one, but deposition took place in the transitional zone between shelf and shoreface. Trough cross-bedded sandstones facies was probably formed by migration of 3D subaqueous dunes in the lower shoreface environment. Facies of horizontally bedded biocalcarenites and biocalcrudites was deposited in the upper shoreface and foreshore environments. Deposits of bioclastic tuffites facies were deposited in the transitional zone between shoreface and shelf, and those of the tuff facies in the shelf area. Succession investigated on the geological column in the area of Čučerje indicates continuous deposition from Carpathian to Lower Badenian. Facies pattern suggests progradation, i.e. regressive trend, at the transition from Carpathian to Badenian, which resulted in shift from shelf deposition towards sedimentation in the transitional zone. Further shallowing trend, i.e. progressive regression resulted in sedimentation of shoreface and foreshore deposits. Subsequent transgressive-regressive trend was marked by deposition in the transitional zone, shelf and again transitional zone environments. Deposits of the upper part of the column indicate on intensified volcanic activity in the neighbouring area, characterized by acid, rhyolitic-dacitic volcanism. Investigated oscillation of the sea level (mainly regressive trend) at the Carpathian to Badenian transition can be positively correlated with the study of the Pannonian Basin deposits (NAGYMAROSY & MÜLLER, 1988).

Karpatian; Badenian; marine sediments; Medvednica Mt.; Croatia; Pannonian Basin

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