Microfacies analysis of the Upper Triassic (Norian) “Baca Dolomite”: early evolution of the western Slovenian Basin (eastern Southern Alps, western Slovenia)

Year, pages: 2010, 293 - 308

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 “Baca Dolomite”, which has, until now, been poorly investigated due to a late-diagenetic 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.

Gale, L. 2010. Microfacies analysis of the Upper Triassic (Norian) “Baca Dolomite”: early evolution of the western Slovenian Basin (eastern Southern Alps, western Slovenia). In Geologica Carpathica, vol. 61, no.4, pp. 293-308. 1335-0552. DOI: https://doi.org/10.2478/v10096-010-0017-0

Gale, L. (2010). Microfacies analysis of the Upper Triassic (Norian) “Baca Dolomite”: early evolution of the western Slovenian Basin (eastern Southern Alps, western Slovenia). Geologica Carpathica, 61(4), 293-308. 1335-0552. DOI: https://doi.org/10.2478/v10096-010-0017-0