Abstract:The study of the Early Miocene (Late Ottnangian/Early Karpatian) ostracod fauna from the Sadovi section (Mt Požeška gora, Croatia) led to several results concerning Neogene paleobiogeography and paleoecology. Brackish deposits of Late Ottnangian and Early Karpatian age have been recognized for the first time in the North Croatian Basin. These deposits indicate the first marine ingression into the Early Miocene lake in this area. Twenty-nine ostracod species were determined, including the new taxa Fabaeformiscandona slavonica nov. sp. and Herpetocypris sadovii nov. sp.
Pontian deposits of the Zagorje Basin constitute a coarsening-upward succession, which reflects the infilling style of this Pannonian sub-basin, i.e. the progradation of clastic systems into the brackish lake. Six facies differentiated correspond to lake floor, channelled slope, distal and proximal pro-delta, distal and proximal mouth bars, and lagoon/bay to swamp and alluvial environments. The deposition in the mouth-bar area was dominated by frictional forces. The upper-stage plane-bed sands are the main mouth-bar facies, which is uncommon in the geological record. The main factors for the origin of such bars include an abundant sand supply by the high-energy fluvial system(s), low-energy of the receiving basin and shallow depositional depth. Prolonged, catastrophic floods generated sustained hyperpycnal flows, which bypassed the mouth-bar area and fed the slope/pro-delta. The high ratio between sediment supply and subsidence rate resulted in a fast moving 'progradational wave', which involved the entire SW Pannonian Basin, including the Zagorje Basin.
Abstract:Deep marine Miocene deposits exposed sporadically in the Medvednica Mt. (northern Croatia) comprise pelagic organisms such as coccolithophores, planktic foraminifera and pteropods. The pteropod fauna from yellow marls at the Vejalnica locality (central part of Medvednica Mt.) encompasses abundant specimens of Vaginella austriaca Kittl, 1886, accompanied with scarce Clio fallauxi (Kittl, 1886). Calcareous nannoplankton points to the presence of NN5 nannozone at this locality. Highly fossiliferous grey marls at the Marija Bistrica locality (north-eastern area of Medvednica Mt.) comprise limacinid pteropods: Limacina valvatina (Reuss, 1867), L. gramensis (Rasmussen, 1968) and Limacina sp. Late Badenian (NN5 to NN6 nannozone) age of these marls is presumed on the basis of coccolithophores. Most of the determined pteropods on species level, except V. austriaca have been found and described from this region for the first time. New pteropod records from Croatia point to two pteropod horizons coinciding with the Badenian marine transgressions in Central Paratethys. These pteropod assemblages confirm the existence of W-E marine connection ("Transtethyan Trench Corridor") during the Badenian NN5 nannozone. Limacinids point to the possible immigration of the "North Sea fauna" through a northern European marine passage during the Late Badenian (end of NN5-beginning of NN6 zone), as previously presumed by some other authors.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.