Application of a mass movement susceptibility model in the heterogeneous Miocene clastic successions of the Slovenj Gradec Basin, northeast Slovenia

In Slovenia, mass movements are not only a threat to the population, but also a major environmental and social science challenge. Lithologically heterogeneous areas have been found to be problematic, and the Miocene Slovenj Gradec basin (in northeast Slovenia) is one such area. For this area, we developed landslide and rockfall susceptibility maps based on detailed geological research combined with statistical modeling schemes. Crucial factors include lithological composition, land use, geological structural elements, slope curvature, aspect and inclination, and bed dipping. The approach taken in the development of mass movement susceptibility maps presented here is transferable to other areas defined by heterogeneous lithology. Such maps could prove useful spatial planning, forestry, environmental protection, landscape architecture, and other fields

Geochemical and mineralogical approaches in unraveling paleoweathering, provenance, and tectonic setting of the clastic sedimentary succession (Western Central Paratethys)

Pronounced tectonic and paleogeographic changes were detected in the Alpine–Pannonian region during the Miocene at the interface between the Alps, the Dinarides, and the Pannonian Basin. To understand the major tectonic, paleogeographic, and paleoclimatic changes during this period, geochemical and mineralogical investigations were carried out on the fine-grained clastic sedimentary rocks in the Tunjice Hills. The paleoweathering indicates a cold and/or arid to a warm and humid period. The paleoclimate and the regional climatic conditions correspond well with the Middle Miocene Climatic Optimum. The mineral composition shows an abundance of quartz and calcite. Quartz is associated with detrital origin from volcanic and metamorphic rocks of the Eastern and Southern Alps and with authigenic processes in sediments. Calcite is related to authigenic origin formed in shallow marine environments and to detrital provenance from the Southern Alps. Not all discriminant functions based on major oxides provided adequate results in determining the tectonic setting. The source rocks were subjected to oceanic island arc and collision. Moreover, sedimentation was influenced by both active and passive margin settings. The former is related to the Alpine collision, which continued from the Cenozoic onward, and the latter is connected to the processes associated with the formation of the Pannonian Basin System, which began in the late Early Miocene

Sedimentary evolution of Slovenj Gradec basin in neogen

Slovenjgraški bazen predstavlja zahodni robni del neogenskega Panonskega bazena in se v strukturnem smislu nahaja na meji Alp ter Panonskega bazena. V njem so se v miocenu odlagali drobno- do debelozrnati sedimenti, ki so bili do sedaj zelo slabo poznani. S pričujočo disertacijo zapolnjujem to veliko znanstveno vrzel. Z uporabo sedimentoloških, petrografskih in geokemičnih analiz ter biostratigrafskih raziskav sem določila sedimentacijska zaporedja, provenienco in tektonsko okolje ter preučevala paleogeografsko evolucijo območja Slovenjgraškega bazena. Nadalje podajam tudi oceno ekonomskega potenciala kamnin Slovenjgraškega bazena ter za območja, ki so zgrajena iz njih, podajam oceno nevarnosti pojavljanja pobočnih masnih premikov. Slovenjgraški bazen predstavlja kompleksno sedimentno enoto, na evolucijo katere so vplivali tektonika, evstatična nihanja morske gladine, bioprodukcija ter podnebne spremembe. Sedimentacija v Slovenjgraškem bazenu se je začela v karpatiju in je trajala do konca zgodnjega badenija. V zaporedju se menjavajo plasti konglomeratov, peščenjakov, meljevcev in laporovcev, ki so nastajali na kopnem (visokoenergijskem rečenem in mirnem močvirskem), v prehodnem (lagunskem in deltnem) in v plitvomorskem sedimentacijskem okolju. Menjavanje okolij je posledica treh regresijsko-transgresijskih cikov, ki so odraz globalnih sekvenčnih ciklov tretjega reda (TB 2.2, TB 2.3, TB 2.4). Bazen se je zasipal predvsem s sedimenti, ki so prihajali iz severne, severozahodne, zahodne in jugozahodne smeri. Provenienco zrn predstavljajo reciklirani orogeni, ki ustrezajo izvoru v Vzhodnih Alpah. Na sedimente sta vplivali dve tektonski okolji. Sedimenti Slovenjgraškega bazena so nastali na območju kolizijske cone, kar odgovarja koliziji Jadranske in Evrazijske plošče ter formaciji Alp. Usedali so se v območju, ki je bilo podvrženo zgodnjeneogenskemu razpiranju ter pogrezanju plošče v karpatijski subdukcijski coni in posledičnem nastanku Panonskega bazena. Kamnine Slovenjgraškega bazena imajo nizek ekonomski potencial, ker gradijo litološko pestra, majhna in lokalno omejena sedimentna telesa. V disertaciji sem testirala tudi prenosljivost modelov verjetnosti pojavljanja pobočnih masnih premikov, na večje merilo. Izdelani sta bili podrobni karti verjetnosti pojavljanja zemeljskih plazov in skalnih podorov v merilu 1 : 5.000. Modela sta se izkazala za zelo natančna in uporabna, saj sta podala zelo dober približek naravnemu stanju.The Slovenj Gradec Basin represents western margin of both, the Pannonian Basin System and the Central Paratethys. It is situated on the border of two geotectonic units: Alps and the Pannonian Basin System. It is filled with fine- to coarse-grained Miocene sedimentary rocks, which are poorly researched. The aim of the present research is to fill part of this scientific gap. Sedimentary successions, provenance, tectonic setting, paleogeographic evolution of the Slovenj Gradec Basin were investigated. The research is based on standard sedimentological procedure, petrographic, geochemical and biostratigraphic analyses. Furthermore, Neogene rocks are quite susceptibile to the formation of slope mass movements, therefore the landslide and rockfall susceptibility models for the investigated area were developed. The deposition of clastic sediments started in the Karpatian and lasted to the end of the Early Badenian. The sedimentary succession is composed of alternation of conglomerate, sandstone, siltsone and marlstone layers, formed in terrestrial (high energy fluvial and swampy), transitional (lagoon and deltaic) and shallow marine environment. Frequent alternation of sedimentional environments is related with regional and global regression-transgression cycles. The sediment input was from the north, north-west, west and south-west direction and correspond to provenance form the Eastern Alps. Sediments were subjected to two different tectonic settings: first related to collision of Adriatic and Eurasian plates, and second to the rifting and formation of the Pannonian Basin System. The area consists of coarse- and fine-grained clastic sedimentary rocks which represent high susceptibility for slope mass movements: rockfalls and landslides. Therefore, based on the rockfall and landslide susceptibility models, the susceptibility maps for mass movements were made which accurately define the areas of different probabilities for the occurrence of rockfalls and landslides. Models gave a very good approximation to the natural state

Miocene paleogeography and biostratigraphy of the Slovenj Gradec Basin: a marine corridor between the Mediterranean and Central Paratethys

The Miocene evolution of the area transitional from the Eastern Alps to the Pannonian Basin System was studied through the paleogeographic evolution of the Slovenj Gradec Basin in northern Slovenia. It is based on mapping, section logging, nannoplankton biostratigraphy, and petrography. The results are correlated with the lithological column of the borehole MD-1/05. The evolution of the basin is connected with the development of the Pannonian Basin System, and the global 3rd order cycles, which influenced the connection with the Mediterranean Sea. Sedimentation started in the Karpatian in a fluvial to lacustrine environment and terminated at the end of the Early Badenian. During this period, three transgression–regression cycles were recorded. The first transgression occurred in the Karpatian and corresponds to the TB 2.2. cycle. The sediments reflect proximity of the hinterland. After a short break in sedimentation, the Early Badenian deposition followed. It marks the second transgression into the SGB, the first Badenian, correlated with the TB 2.3 cycle. There are signs of a transitional environment, which evolved to marine in advanced stages. At the high-stand system tract, the sea flooded the entire Slovenj Gradec Basin. Subsequent reduced quantity and diversity of the microfossils marks the onset of the second regression stage. It is followed by the third transgression, the second in the Badenian, correlated with the TB 2.4 cycle. The late Early Badenian deposition continued in the lower-energy, though occasionally still turbulent environment. Silty sediments with upward increasing content of organic matter indicate shallowing of the basin, until its final diminishing. Layers of fresh-water coal already bear witness to the existence of restricted swamps. After the Early Badenian, the area of the Slovenj Gradec Basin became dry land, exposed to erosion