Sedimentna evolucija slovenjgraškega bazena v neogenu

Ivančič, Kristina (author), Šmuc, Andrej (mentor), Novak, Matevž (comentor)

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.

• Language: Slovenian
• Keywords: sedimentacijsko okolje, provenienca, miocen, pobočni masni premiki, sekvenčni cikli
• Work type: Doctoral dissertation
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-113226
• COBISS.SI-ID: 1530462
• Publication date in RUL: 15.12.2019

Secondary language

• Language: English
• Title: Sedimentary evolution of Slovenj Gradec basin in neogen

Abstract

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.

• Keywords: depositional environment, provenance, Miocene, slope mass movements, sequence cycles