Stratigraphy and Palaeogeography of Miocene Deposits from the Marginal Area of Žumberak Mt. and the Samoborsko Gorje Mts. (Northwestern Croatia)

Abstract

Miocene sediments rimming the Palaeozoic–Mesozoic–Palaeogenerocks, form Žumberak Mt. and the Samoborsko Gorje Mts. Spatialanalysis of the setting and development of the surface Miocenestratigraphy, at the marginal areas of the Žumberak and SamoborskoGorje Mts., allows four palaeogeographic areas to be distinguished:Žumberak, Plešivica–Sveta Jana, Samobor–Sveta Nedelja and Grdanjci.In the Miocene deposits (totaling 350 m), within the area ofŽumberak, coarse-grained clastics from deltaic deposits of Pannonianage prevail. Here only, 50 m of sediments of Pliocene–Pleistoceneage overlie the Miocene deposits whereas Mesozoic carbonates representthe basement. The Plešivica–Sveta Jana area is characterizedby a 600 m sequence of Miocene deposits, mainly overlying Triassicdolomites, where finely-grained layers of marls and silts prevail.In this area, Miocene successions from the Badenian to the Pontianare characterized by a continuity of sedimentation with an inheriteddepositional environment. In the area of Samobor–Sveta Nedelja,the basement is diverse: Triassic dolomites, volcanogenic–sedimentarycomplex of Cretaceous age and a clastic–carbonate complex ofPalaeogene age. The Miocene succession shows a regressive trendfrom the Badenian to the Pontian and the total thickness is estimatedat 400 m. The area of Grdanjci differs considerably from the otherMiocene palaeorelief. An approximately 50 m-thick series of coarsegrained clastics with coal is distinguished, of unclear stratigraphic age (Ottnangian?). Miocene sediments of the Grdanjci area are represented by both a transgressive type of conglomerates and shallow water limestones of Badenian age, with a total thickness of about 100 m.The development of the Miocene stratigraphy of the Žumberakand Samoborsko Gorje Mts. is generally correlative with that in theother parts of the Pannonian area, though it does exhibit local variations.Comparison of the Miocene palaeorelief of Žumberak Mt. withthe Samoborsko Gorje Mts., together with neighbouring areas, enabledwider correlation with other parts of northern Croatia, and themore distant Western and Central Paratethys.