In the master's thesis, I described and stratigraphically placed the sequence of limestone breccias around the area of Mt. Matajur. The area of research is located on the northern slope of the mountain, about 5 km southeast of Kobarid (NW Slovenia). Structurally, the area is located at the transition between the External Dinarides and the Southern Alps. The area most likely belongs to the External Dinarides, more specifically to the Trnovo Nappe. The latter consists of the Mesozoic succession of the Dinaric Carbonate Platform. The northern edge of the platform, where the succession preserved on Mt. Matajur was likely positioned, has already begun to disintegrate and drown in the Jurassic. For this reason, the post-drowning developments of the Mt Matajur area are generally similar to those of the southern margin of the Slovenian Basin, but are more condensed, show more stratigraphic gaps, and are generally more calcareous.
I reambulated and expanded the pre-existing geological map of the Mt Matajur area and logged two detailed sedimentological sections, covering most of the Jurassic and part of the Cretaceous succession. The field work was followed by a microfacies analysis. The Jurassic formations were dated on the basis of foraminifers.
Jurassic succession of the Mt. Matajur begins with the Lower Jurassic, shallow-marine ooidic limestone, followed by the deep-marine limestone sequence of Middle to Upper Jurassic age, including two layers of limestone breccias, which are the main subject of this research. The breccias are overlain by calcarenites and cherty micritic limestones, which gradually turn into the Bianconetype micritic limestone that terminates the Jurassic sequence. Following unconformity, Lower Cretaceous limestone breccias, calcarenites and micritic limestones with cherts deposited, followed by red Scaglia rossa type limestone. The sequence ends with the uppermost Cretaceous flysch that begins with basal limestone breccia that is followed upwards by a flysch development, which still contains limestone-brecciamegabeds.
The limestone breccia unit is Middle Jurassic in age, as determined by foraminifer Protopeneroplis striata Weynschenk. These beds formed by debris flows that originated from the disintegrating northern margin of the Dinaric Carbonate Platform. It correlates with the limestone blocky breccias of the same age, which deposited along the entire southern margin of the Slovenian Basin, with the difference that the gravitational events on Mt. Matajur are of smaller dimensions.
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