Decastronema barattoloi (DE CASTRO), characteristic fossil of the Palaeocene and the Eocene peritidal sediments from the Adriatic carbonate platform

The renewed deposition in the Palaeogene and the oldest part of the non-interrupted Palaeocene succession is characterized by the presence of Decastronema barattoloi (DE CASTRO), cyanobacterial tubes originally described in the Apennines. The reinterpretation of limestones from several sections located in the Kras region (NW part of the AdCP: Basovizza, Dolenja vas, Sopada, Čebulovica) confirmed the presence of these microfossils in peritidal sediments of Danian age (SBZ 1). The Cuisian (Late Lower Eocene) sediments, from eastern Istria (Brnjci section), Cres Island (Koromačna Cove section) and Ravni kotari (Benkovac–Korlat section) contain individuals of this species in great numbers. The cyanobacterial tubes are scattered in laminated, fine grained mudstones and wackestones, immediately above the Cretaceous sediments (occasionally above bauxites or breccias). The Decastronema-bearing sediments pass upward into the Foraminiferal limestones of Cuisian age (SBZ 11, based on conical agglutinated foraminifera and alveolinids), allowing the age determination of the cyanobacterial remnants. The Palaeocene specimens are minute (up to about 180 μm long), thick walled tubes that occur with the index fossil Bangiana hanseni DROBNE. The Eocene forms accompanied by ostracods, pelecypods, and miliolid and rotaliid foraminifera are segmented tubes, up to 400 mm long and usually thin walled

Microfacies of Mesozoic Carbonate Rocks of Slovenia

Carbonate rocks of Mesozoic age are widespread in Slovenia where they consitute about 40 % of its territory, and attaining total thickness of more than 5000 metres. With respect to microfacies almost all structure types can be recognized, the limestones and dolomites being formed in various sedimentary environments, such as in openand in restricted parts of carbonate shelf, in lagoons and on coastal plains, in different types of reefs, on slopes and in the basin. Carbonate sedimentation was often accompanied also by the supply of terrigenous material and products of volcanic activity. Among diagenetic processes in investigated carbonate rocks the most extensive are dolomitization and silicification.In the present text 250 microscopic photographs of characteristic limestones and dolomites from Slovenian territory are assembled. In the introductory part, to which for orientation schematic stratigraphic columns are added,the geologic development od these carbonate rocks is briefly outlined. For the sake of completeness in presenting the »carbonate era« in the overview, Upper Permian limestones and dolomites are also described next to Mesozoic beds

Lower Jurassic beds at Preserje near Borovnica (Central Slovenia)

Described is a 50 m thick cross-section, which includes 26 cyclothems. Beds of biomicritic, in some places oolitic, limestone are interrupted by dolomitized laminites, thinner beds of flatpebble conglomerate,and rarely stromatolites. The bedrock of the cross-section is sparitic dolomite. The contact between Triassic and Jurassic is not included in the cross-section. Lithological varieties indicate sedimentation in the subtidal zone in the protected part of a shallow shelf within the Adriatic Dinaric carbonate platform with occasional connection with the open sea. Dolomite in the laminites and flatpebble conglomerate is of early diagenetic origin.It developed through capillary concentration of pore solutions in intratidal and supratidal environment. The Lower Jurassic age of the limestone is determined by Palaeodasycladus mediterraneous Pia algae. Chemical analyses include Ca, Mg, as well as, Sr, Fe, Mn and Na. Beds containing dolomite of early diagenetic origin are rich with Fe and Na

Deep-water Triassic and Jurassic beds from Mt. Kobla (W Slovenia)

This contribution deals with geological setting of Mt. Kobla which is situated in the central part of the Bohinj ridge, and brings a review of the previous geological studies in the area.The first detailed studies are closely related to a 6334 m long Bohinjska Bistrica–Podbrdo railway tunnel which was opened in 1906. The tunnel is constructed just under the peak of Mt. Kobla and encompasses 8 lithological members. The second period of intensive geological studies is related to elaboration of the Basic Geological Map, scale 1:100.000, Sheet Tolmin that were carried out from 1969–1987. During this time, Middle Triassic to Late Cretaceous existence of Slovenian Basin and two platforms in western Slovenia was established. In the past decade geological studies in the area have been focused on detailed stratigraphy and lithology. The analysis of conodont assemblages and foraminifers indicates that a part of limestone classified in Basic Geological Map as Lower Jurassicare actually of the Upper Triassic age.Jurassic sediments in Mt. Kobla were settled in deep-marine environment of the Slovenian Basin. Limestone breccias and calcarenites were transported by gravitational currents from the shelf edge to the slope and to the basin. In Lower Jurassic calcarenite with abundant reworked ooids and crinoids occur

Badenian rhodolith in Kozjansko (E Slovenia)

Rhodolith beds are the basal transgressive unit of the several hundred metres thick Badenian succession, and are a pecuharity of the Kozjansko area.Rhodoids are mainly spherical having up to 15 cm in diameter. They are built of Lithothamnium corallinacean algae with crusty and branching texture, frequently intergrown with bryozoans. The rhodoid nuclei commonly consist of pebbles of Palaeozoic clastic rocks (quartz, phyllites), Triassic carbonates and Oligocene tuffs.The rhodolith occasionally passes into a rhodolithic conglomerate. Sparsely rhodoids of somewhat smaller dimensions also occur in lithothamnium limestone (biocalcarenite). Rhodolith was formed in nearshore, well agitated areas of the Tertiary Kozjansko basin

Younger Paleozoic, Mesozoic and Tertiary oolitic and oncolitic beds in Slovenia – An Overview

Oolitic and oncoidal rocks, microfacies, depositional environments and their stratigraphic ranges in Sloveniaare subjects of this article. Various types of calcareous ooids are present in the Upper Carboniferous, Permian andTertiary (Paleocene and Miocene) beds and specially at many levels in an up to 6000 meters thick statigraphic successionof the Mesozoic age. Sedimentological investigations have been carried out specially in the Triassic andJurassic beds. The ooids occurring in the shallow-water and intertidal carbonate environment have been groupedinto seven types and oncoids into four types. Oncoids are rather more aboundant in Carnian and Norian/Rhaetianage. Late dolomitization of some oolitic beds is next to cementation the main diagenetic feature

Mikrofazies, Diagenese und Geochemie des Dachsteinkalkes und Hauptdolomits in Süd-West-Slowenien

Eine bis zu 1000 m mächtige Schichtenfolge von karbonatischen Gesteinen des norischen und rätischen Alters ist in dem südwestlichen Teil Sloweniens als Hauptdolomit, nur in den Gebieten von Trnovski gozd und Banjska planota sind die oberen 200m überwiegend als Dachsteinkalk entwickelt.Der Hauptdolomit zeigt Markmale der loferitischen Entwicklung. Bis zum Meter mächtige Schichten von biomikritischem und körnigem Dolomit wechseln sich mit dünneren Stromatolith-und Laminit-Schichten rhytmisch ab. Das Ablagerungsmilieuvon Hauptdolomit war ein sehr flacher abgeschlossener Schelf,häufig der intertidale Bereich innerhalb der Dinarischen Karbonat-Plattform.Der Dolomit ist in der frühen Diagenese (Stromatolith-Schichten) sowie während der spätdiagenetischen Prozesse (körniger Dolomit) entstanden. Der Dachsteinkalk stellt eine laterale Fazies des Hauptdolomits vor. Das Gestein wurde in einem offenen Flachschelf abgelagert. Für ein intertidales Milieu kennzeichende Sedimenttexturen sind selten. Die Korrosionshohlräumeund intraformationelle Brekzien in dem Kalkstein zeigen auf kurzfristige lokale Varlandungen während seiner Entstehung.Auf die geochemische Zusammensetzung von Spurenelementen der Kalke und Dolomite hatten die diagenetischen Prozesse, vor allem die Dolomitisierung, weniger aber das Sedimentationsmilieu den grössten Einfluss. Die Kalksteine enthalten in Vergleich zum Dolomit allgemein zweimal mehr Sr, die Dolomite aber mehr Fe, Mn und Na. Der frühdiagenetische Dolomit ist mit den schwerenIsotopen δ013 und δC13 angereichert, wogegen der spätdiagenetische Dolomit mehr des leichten δО18 enthält. Der Kalkstein wurde bei Temperaturen um 24°C abgelagert