Biostratigraphic and sedimentological analysis of Triassic beds at Preddvor

Na jugovzhodnem pobočju hriba Kozjek nad Mačami pri Preddvoru je bilo odkrito zaporedje tankoplastnatih dolomitov, apnencev in laporjev. V diplomskem delu sem posnela sedimentološki profil zaporedja, ga skušala umestiti med že znane litostratigrafske enote Kamniško-Savinjskih Alp, ter s pomočjo mikrofosilov določila starost enote. Na terenu sem odvzela šest vzorcev za konodontno analizo in 13 vzorcev apnenca za zbruske. Na podlagi zbruskov sem določila osem mikrofaciesov in sicer: laminirani bioklastični peloidni wackestone (?), laminirani mudstone, rekristalizirani wackestone, mudstone s posamičnimi ploščicami iglokožcev, foraminiferni peloidni wacke/packstone, ostrakodni peloidni packstone in ostrakodni peloidni grainstone ter bioklastični intraklastični packstone. Rezultati konodontnih analiz so bili negativni, v zbruskih pa je prisotna foraminifera Pilammina densa, ki je značilen fosil srednjega in zgornjega anizija. Prisotnost sinsedimentno splazelih plasti kaže na sedimentacijo na nagnjenem morskem dnu. Primerjava mikrofaciesov s standardnimi mikrofaciesi ne daje enoznačne interpretacije sedimentacijskega okolja. Odlaganje plasti bi tako lahko potekalo v poglobljeni laguni znotraj platforme, ali na pobočju nekoliko globljega morskega bazena. Relativno majhna debelina plasti kaže, da globina lagune ali bazena ni presegla par 10 m. Posneto zaporedje se litološko precej dobro ujema z opisom Strelovške formacije, ki je bila do sedaj starostno opredeljena zgolj na podlagi superpozicije.A sequence of thin-layered dolomites, limestones and marls was found on south-eastern slope of hill Kozjek above Mače near Preddvor. In this diploma work I recorded sedimentological log of the sequence, tried to place it among the already known litostratigraphic units of the Kamnik-Savinja Alps and determine the age of the unit with the help of microfossils. Therefore, six samples were taken for conodont analysis and 13 samples of limestone for thin sections. Eight microfacies types were identified from thin sections: laminated bioclastic peloid limestone (?), laminated mudstone, recrystallized wackestone, mudstone with individual echinoderm plates, foraminiferal peloid wacke/packstone, ostracode peloid packstone and ostracode peloid grainstone and bioclastic intraclastic packstone. Conodont analysis proved to be negative, but microfossil foraminifera Pilammina densa was found in thin sections. The latter is typical for the middle to upper Anisian epoch. The presence of slumps indicates sedimentation on a sloping seabed. Comparison of microfacies with standard microfacies does not give unambigous interpretation of the sedimentary environment. The deposition of layers could take place in a deepened lagoon inside the platform, or on the slope of slightly deeper sea basin. Relatively small thickness of succession indicates that the depth of the lagoon or pool did not exceed a couple of tens of meters. The recorded sequence lithologically corresponds with the description of the Strelovec formation. Thus far, the age of the latter was defined solely on the basis of superposition