The master's thesis with the title "Lower Triassic Carbonate Clastic Sequence with Limonite Formations near Klada" was conducted in the Klada area near Ig, south of Ljubljana Our research focused on the Lower Triassic sedimentary sequence of clastics and carbonates, which exhibited a distinct clastic development unlike other manifestations of the Werfen Formation's releases. Within the fine-grained part of the sequence, we discovered limonite formations of a unique nature. To comprehend the geological phenomenon, we recorded a 138 m stratigraphic profile and extracted two detailed profiles within it. Based on lithological characteristics, we classified the lithological sequence into three lithostratigraphic units (LE). To precisely determine lithologies, we prepared 29 petrological thin sections and 2 slides. We conducted geochemical and mineralogical analyses on the samples and examined the slides under a scanning electron microscope.
In the first lithostratigraphic unit (LE1), we placed coarse-grained clastics that could be partially classified as Carboniferous-Permian clastics. In the second lithostratigraphic unit (LE2), we assigned sequences of clastics of either Permian or Lower Triassic age. In the third lithostratigraphic unit (LE3), we described the alternation of clastics and carbonates of the Lower Triassic Werfen Formation.
As a particularity of the upper part of LE3, we described cellular textures of limonite formations within poorly cohesive clay layers. To understand these formations, we conducted mineralogical and geochemical analyses of the formations and the surrounding poorly cohesive clay on questioned samples and slides.
Based on the results, we estimate that the limonite formations within the poorly cohesive clay are a result of the percolation of meteoric water enriched with mobile iron and manganese through fractures and areas of higher porosity and permeability.
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