Evolucija rudonosnih fluida u olovno-cinčanom ležištu Mežica, Slovenija

master's thesis

• Title (english): Evolution of ore-forming fluids at the Mežica Pb-Zn deposit, Slovenia
• Author: Matea Marenković
• Mentor: Andrea Čobić (mentor)
• Mentor: Sabina Strmić Palinkaš (mentor)
• Committee member: Andrea Čobić (predsjednik povjerenstva)
• Committee member: Nenad Tomašić (član povjerenstva)
• Committee member: Karmen Fio Firi (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Geology); Zagreb
• Defense date and country: 2019-12-16, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Geology; Mineralogy and Petrology

Abstract

Brojne Pb-Zn pojave poznate su u trijaskim sedimentima Istočnih i Južnih Alpa, kao i duž Periadrijastkog lineamenta (npr. Topla, Bleiberg, Mežica), ali porijeklo tih ležišta je i dalje sporno. Olovno-cinčano ležište Mežica predstavlja klasičan primjer za ovaj tip mineralizacije. Ležište je smješteno u Sjevernim Karavankama Istočnih Alpi u Sloveniji. Mineralizacija se nalazi u trijaskim platformnim karbonatnim naslagama. Ležište je formirano tijekom kasnog trijasa do rane jure pod utjecajem termalnih fluida u ekstenzijskom režimu. Glavni rudni minerali su galenit i sfalerit, dok su kalcit i dolomit glavni jalovinski minerali. Provedene analize fluidnih inkluzija ukazuju da je glavni mehanizam nastanka Pb-Zn ležišta Mežica miješanje rudonosnog fluida koji je prenosio metale s razrijeđenim fluidima vjerojatno meteorskog porijekla. Smanjeni salinitet destabilizira metal-kloridne komplekse i smanjuje sposobnost fluida u prenošenju metala, te omogućava precipitaciju rudnih minerala. Postrudni karbonati formirani su pod utjecajem CO2 koji potječe iz oksidacije organske tvari ukazujući da je organska tvar iz dolomita mogla doprinijeti reduktivnim uvjetima u sustavu. Podaci fluidnih inkluzija dobiveni iz wulfenita i supergenih karbonata ukazuju da je fluid bio razrijeđena vruća voda.

Abstract (english)

Numerous Pb-Zn occurrences are known in Triassic sediments of the Eastern and Southern Alps as well as along the Periadriatic Lineament (e.g. Topla, Bleiberg, Mežica) but the origin of these deposits is still somewhat controversial. The Mežica Pb-Zn ore deposit represents a classic example for this type of mineralization. The deposit is located in the Northern Karavanke geotectonic unit of the Eastern Alps in Slovenia. The mineralization is hosted by Triassic platform carbonates. The deposit was formed in Late Triassic to Early Jurassic by thermally driven fluid flow during the crustal extension. Galena and sphalerite are the main ore minerals while calcite and dolomite are the most common gangue minerals. Obtained fluid inclusion data suggest that the main mechanism for formation of the Pb-Zn Mežica deposit is mixing of metal-bearing brines with deluted fluids of presuamably meteoric origin. The decreased salinity destabilized metal-chloride complexes and reduced the fluid capacity to transport base metals, enabling precipitation of ore minerals. Post-ore carbonates formed under the influence of CO2 originating from oxidation of organic matter, indicating that organic matter from host dolomite might have contributed to reductive conditions in the system. Fluid inclusions data obtained from wulfenite and supergene carbonates revealed that the descending fluids were deluted hot water.

• Keywords: fluidne inkluzije; karbonati; Mežica; Pb-Zn rudno ležište; sfalerit
• Keywords (english): carbonate; fluid inclusions; Mežica; Pb-Zn ore deposit; sphalerite
• Language: croatian
• URN:NBN: urn:nbn:hr:217:817361
• Study programme: Title: Graduate university study of Geology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra geologije (magistar/magistra geologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-01-21 09:34:53