Divergent drift of Adriatic-Dinaridic and Moesian carbonate platforms during the rifting phase witnessed by triassic MVT Pb-Zn and SEDEX deposits; a metallogenic approach

Early-intracontinental rifting of Pangea is result of thermal doming in Uppermost Permian time giving rise to the formation of horst-graben  structures, followed by slow subsidence, marine transgression and evaporate deposition. Consequence of incipient magmatism are numerous geothermal fields and subterrestrial hydrothermal siderite-barite-polysulfide deposits (PALINKAŠ et al, this issue). Advanced rifting magmatism as a successive stage in Middle Triassic brought intensive submarine volcanism, accompanied by coeval sedimentation of chert and siliciclastics, building up volcanogenic-sedimentary formations. Volcanic activity with explosive phases and generation of large volumes of pyroclastic rocks in the rifts produced concomitant mineralization with numerous SEDEX deposits of Fe-Mn-Ba-polysulfides. Passive continental margins flanked by the Adria-Dinaridic carbonate platform as passive continental margin of the northern Gondwanaland and Moesian carbonate platform, as a counterpart on the European passive continental margin, were divergently drifted in the coarse of the advanced rifting. A fast growing carbonate platforms, developing gradually, covered  evidences of the earlier intracontinental rifting and their ore formations. On the other hand, the carbonate platforms themselves host specific Pb-Zn deposit, well known as Mississippi valley type, (MVT) or Bleiberg-Mežica type according the traditional european terminology. Triassic MVT and SEDEX deposits are symmetrically situated on the both sides of the divergent passive margins in this early history of the Tethyan ocean.</p

Origin and K-Ar age of the phreatomagmatic breccia at the Trepča Pb-Zn-Ag skarn deposit, Kosovo: Implications for ore-forming processes

The Trepča Pb-Zn-Ag skarn deposit in Kosovo is spatially and temporarily related to the phreatomagmatic breccia of Oligocene age (~23 Ma). The deposit shows features typical for skarn deposits worldwide, including a stage of isochemical metamorphism, a prograde stage of an anhydrous, low oxygen and low sulfur fugacity character and a retrograde stage characterized by an increase in the water activity as well as by an increase in oxygen and sulfur fugacities. The mineralization is hosted by the recrystallized Upper Triassic limestone. The prograde mineralization consists mainly of Ca-Fe-Mn±Mg pyroxenes. The host recrystallized limestone at the contact with the prograde (skarn) mineralization have the increased content of Fe, Mn, Mo, As, Au, Cs, Ga, REE and Y suggesting their transport by infiltrating magmatic fluids. The decreased  d13C and  d18O values reflect a contribution of magmatic CO2. The retrograde mineral assemblage comprises ilvaite, magnetite, arsenopyrite, pyrrhotite, marcasite, pyrite, Ca-Fe-Mn±Mg carbonates and quartz. Hydrothermal ore minerals, mostly galena, sphalerite and pyrite, were deposited contemporaneously with the retrograde stage of the skarn development. Syn-ore and post-ore carbonates reflect a diminishing influence of magmatic CO2. Syn-ore carbonates are enriched in Fe, Mg, Mn, many chalcophile elements, including Ag, As, Bi, Cd, Cu, Pb, Sb and Zn, as well as in Au, Y and REE. The post-ore stage accompanied the precipitation of significant amount of Ca-rich carbonates including the travertine deposits at the deposit surface. The phreatomagmatic breccia was developed along a NW dipping contact between the ore bearing recrystallized limestone and the overlying schist. It has an inverted cone shape with the vertical extension up to 800 m and diameter up to 150-m. The upper part of the diatreme (an underground segment of the phreatomagmatic breccia) is characterized by the presence of a hydrothermally altered rootless quartz-latite dike surrounded by an unsorted polymict breccia mantle. Despite the alteration processes, the dike has a preserved porphyritic texture. Partly preserved sanidine, accompanied with the mixture of muscovite and quartz, reflects a near-neutral to weakly acidic environment. The clasts of country rocks and skarn mineralization underwent intense milling and mixing due to repeated magmatic penetrations. Sericitization of the breccia matrix, locally accompanied with minor kaolinitization, point to an increased water activity under near-neutral to weakly acidic conditions. Large fragments originally composed of anhydrous skarn minerals (pyroxenes) are usually completely altered to a mixture of fibroradial magnetite, quartz and various amount of carbonates suggesting an increase in oxygen fugacity. Their pyrite rims reflect that the increase in oxygen fugacity was followed by an increase in sulfur fugacity. The clast predominantly composed of Fe-sulfides and minor Bi-sulfides point that the increase in sulfur fugacity was locally sufficient to complete sulfidation of hedenbergite to pyrrhotite and/or pyrite. Although the phreatomagmatic breccia at the Trepča Pb-Zn-Ag skarn deposit does not carry significant amounts of the ore mineralization, its formation was crucial for the ore deposition. Phreatomagmatic explosions and formation of the breccia turned the system from the lithostatic to hydrostatic regime and triggered the retrograde stage increasing the water activity and oxygen fugacity in the system. In addition, cooling and decompression of the system contributed to more effective degassing of magmatic sulfur increased the sulfur fugacity. </p

Lifelong learning of librarians

Tema diplomskog rada cjeloživotno je obrazovanje knjižničara i kako se ono provodi u Republici Hrvatskoj. U teorijskom se dijelu rada polazi od pitanja što je cjeloživotno obrazovanje te se navodi važnost obrazovanja odraslih, koji su osnovni resurs za razvoj modernog društva. Nadalje, pobliže se objašnjava nastanak i razvoj koncepta cjeloživotno učenje koji se kasnije mijenja u cjeloživotno obrazovanje. Zatim se cjeloživotno obrazovanje promatra kroz nekoliko vrsta znanosti, odnosno kroz psihologiju, sociologiju i ekonomiku. Slijedeća je tema cjeloživotno obrazovanje knjižničara, opisuju se sva potrebna znanja koja knjižničar u suvremenom svijetu mora imati kako bi pružao što kvalitetnije usluge. Knjižničarstvo postaje profesija koja knjižničarima omogućuje ostvarivanje karijere. Stručno usavršavanje knjižničarima služi kao nadopuna znanja, a u radu se opisuju online tečajevi koji predstavljaju najelastičniji model obrazovanja. Jedan dio teorijskog dijela opisuje kakvo je poimanje cjeloživotnog obrazovanja u Hrvatskoj te su navedeni projekti koje provodi Nacionalna i sveučilišna knjižnica zajedno s projektnim partnerima. Na kraju teorijskog dijela opisuje se na koji način knjižničari pružaju potporu u cjeloživotnom obrazovanju svojih korisnika. Instrument istraživanja bila je anketa putem koje je ispitano 299 knjižničara zaposlenih u različitim knjižnicama u Republici Hrvatskoj. Anketom se željelo ispitati provodi li se cjeloživotno obrazovanje knjižničara u knjižnicama Republike Hrvatske, koliko često i na čiju inicijativu te mišljenja i stavovi ispitanika vezani uz mogućnosti cjeloživotnog obrazovanja u Hrvatskoj. Analizom rezultata ankete potvrđene su tri hipoteze (H1: Ispitanici mlađe i srednje dobne skupine češće se cjeloživotno obrazuju od ispitanika starije dobne skupine, H2: Prema mišljenju ispitanika cjeloživotno obrazovanje knjižničara slabije je zastupljeno u Republici Hrvatskoj, nego u nekim zapadnim zemljama, H5: U Republici Hrvatskoj knjižničari se rijetko obrazuju putem online tečajeva). Prema analizi rezultata odgovora ispitanika, hipoteza da jako mali broj knjižnica u Republici Hrvatskoj financira cjeloživotno obrazovanje svojim zaposlenicima djelomično je prihvaćena, a hipoteza da knjižničari s većim stupnjem obrazovanja izdvajaju više novca za cjeloživotno obrazovanje može se odbaciti