Abstract:The Julian Alps (western Slovenia) structurally belong to the eastern Southern Alps. The Upper Triassic succession mostly consists of shallow water platform carbonates of the Dolomia Principale-Dachstein Limestone system and a deep water succession of the Slovenian Basin outcropping in the southern foothills of the Julian Alps. In addition to the Slovenian Basin, a few other intraplatform basins were present, but they remain poorly researched and virtually ignored in the existing paleogeographic reconstructions of the eastern Southern Alps. Herein, we describe a deepening-upward succession from the Tamar Valley (north-western Slovenia), belonging to the Upper Triassic Tarvisio Basin. The lower, Julian-Tuvalian part of the section comprises peritidal to shallow subtidal carbonates (Conzen Dolomite and Portella Dolomite), and an intermediate carbonate-siliciclastic unit, reflecting increased terrigenous input and storm-influenced deposition (Julian-lowermost Tuvalian shallow-water marlstone and marly limestone of the Tor Formation). Above the drowning unconformity at the top of the Portella Dolomite, Tuvalian well-bedded dolomite with claystone intercalations follows (Carnitza Formation). The latter gradually passes into the uppermost Tuvalian-lowermost Rhaetian bedded dolomite with chert and slump breccias, deposited on a slope and/or at the toe-of-slope (Bača Dolomite). Finally, basinal thin-bedded bituminous limestone and marlstone of Rhaetian age follow (Frauenkogel Formation). The upper part of the Frauenkogel Formation contains meter-scale platform-derived limestone blocks, which are signs of platform progradation. The Tarvisio Basin may have extended as far as the present Santo Stefano di Cadore area, representing a notable paleogeographic unit at the western Neotethys margin.
Abstract:The Slovenian Basin represents a Mesozoic deep-water sedimentary environment, situated on the southern Tethyan passive margin. Little is known about its earliest history, from the initial opening in the Carnian (probably Ladinian) to a marked deepening at the beginning of the Jurassic. The bulk of the sediment deposited during this period is represented by the Norian-Rhaetian "Bača Dolomite", which has, until now, been poorly investigated due to a latediagenetic dolomitization. The Mount Slatnik section (south-eastern Julian Alps, western Slovenia) is one of a few sections where the dolomitization was incomplete. Detailed analysis of this section allowed us to recognize eight microfacies (MF): MF 1 (calcilutite), MF 2 (pelagic bivalve-radiolarian floatstone/wackestone to rudstone/packstone), MF 3 (dolomitized mudstone) with sub-types MF 3-LamB and MF 3-LamD (laminated mudstone found in a breccia matrix and laminated mudstone found in thin-bedded dolomites, respectively) and MF 3-Mix (mixed mudstone), MF 4 (bioturbated radiolarian-spiculite wackestone), MF 5 (fine peloidal-bioclastic packstone), MF 6 (very fine peloidal packstone), MF 7 (bioclastic wackestone) and MF 8 (crystalline dolomite). The microfacies and facies associations indicate a carbonate slope apron depositional environment with hemipelagic sedimentation punctuated by depositions from turbidites and slumps. In addition to the sedimentary environment, two "retrogradation-progradation" cycles were recognized, each with a shift of the depositional setting from an inner apron to a basin plain environment.
The "Podpe~ limestone" outcropping south of Ljubljana (Central Slovenia), deposited at the northern edge of the Dinaric Carbonate Platform, comprises mostly dark grey and black thick bedded oolitic limestone, and is renowned for several horizons of lithiotid bivalves. Foraminifera, especially Orbitopsella spp., are rather frequent, but no detailed distribution of foraminiferal taxa was given. Furthermore, documentation of foraminiferal species is scarce, with few photographs. In order to give a comprehensive picture of foraminiferal assemblage of the "Podpe~ limestone" and its distribution, three sections were measured in detail and sampled. The foraminiferal assemblage consists of 17 species, described in detail. On the basis of foraminifera, the investigated part of the "Podpe~ limestone" belongs to the Lituosepta recoarensis and Orbitopsella praecursor biozones of early Late Sinemurian and Early Pliensbachian age, respectively. Izvle~ekTemno sivi in ~rni plastnati ooidni "podpe{ki apnenec", ki ga najdemo južno od Ljubljane (osrednja Slovenija), je nastajal na severnem robu Dinarske karbonatne platforme in je znan po ve~ horizontih litiotidnih {koljk. Poleg ostale makrofavne, so v njem dokaj pogoste tudi foraminifere, posebno Orbitopsella spp. Žal so ta poro~ila slikovno slabo dokumentirana in ponavadi brez natan~ne stratigrafske umestitve. Da bi prou~ili celotno foraminiferno združbo in razpon posameznih taksonov, sem posnel tri detajlne sedimentolo{ke profile. Na podlagi presekov v zbruskih sem dolo~il 17 vrst bento{kih foraminifer in ugotovili, da raziskani del združbe "podpe{kega apnenca" pripada Lituosepta recoarensis in Orbitopsella praecursor bioconama zgodnje poznesinemurijske in zgodnjepliensbachijske starosti.
This study presents the results of the conodont biostratigraphy and microfacies analysis carried out on the pelagic limestones of the Upper Triassic Dovško Section in Slovenia, which represents the eastern part of the Slovenian Basin. The age of the section ranges from the Lacian 1 to the Alaunian 1. The Lacian part of the succession is predominantly characterized by the representatives of the genus Ancyrogondolella. Transitional morphologies towards Alaunian faunas first appear in the Lacian 3 and become common during the Lacian-Alaunian transition. This evolutionary development coincides with a shift in microfacies from a dominantly radiolarian-bearing mudstone-wackestone-packstone to a filament- dominated wackestone-packstone, and the formation of small neptunian dykes, which may reflect environmental perturbations and/or a change in basin geometry. The proliferation of the genera Epigondolella and Mockina is observed in the Alaunian part of the section, though the genus Ancyrogondolella is still present in this interval. Systematic description of the conodont taxa is provided, and seven new species and two new subspecies are established. The new advances will be of great value in further biostratigraphic studies, especially in areas without ammonoid faunas, and in the reconstruction of the paleogeography of the Slovenian Basin.
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