Naslov
Multivariate relationships and spatial distribution of geochemical characteristics of Lower Paleogene bauxites in Croatia

Autori
Kovačević Galović, Erli ; Ilijanić, Nikolina ; Peh, Zoran ; Miko, Slobodan ; Hasan, Ozren

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Bul. Shk. Gjeol. special issue 2014/2 ; Proceedings of XX CBGA Congress, Tirana, Albania / Beqiraj, Arjan ; Ionescu, Corina ; Christofides, Georgios ; Uta, Andreea ; Goga Beqiraj, Enkeleida ; Marku, Sokol - Tirana, Albania, 2014, 216-216

Skup
XX CBGA Congress, Tirana, Albania, 24-26 September 2014

Mjesto i datum
Tirana, Albanija, 24.09.2014. - 26.09.2014

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Bauxite, Croatia

Sažetak
For a long time, bauxites were treated only as an aluminum ore, focusing all research towards their detection, exploitation and refining. Despite a great number of mineralogical and chemical analyses from bauxite deposits and occurrences in Croatia being available in various studies and professional reports, the bauxite genesis was largely underestimated. Only lately, the models of orogenic evolution of the Adriatic Carbonate Platform (AdCP) region have underlined the importance of a number of hiatuses of variable duration marked by bauxitic deposits. Since bauxites are recently recognized as tectonic and climatic event markers at regional unconformities, new investigations call for additional correlative studies within and across different stratigraphic horizons, thus enabling the utilization of this immense potential indispensable in building the regional models of platform evolution. Croatian bauxites are hosted in carbonate rocks marking the regional unconformities between several stratigraphic levels of which the Lower Paleogene bauxites are specifically targeted, owing to their variable time span of emplacement (Lower Cretaceous to Lower Eocene) within the AdCP as the extent of subaerial exposure during the stratigraphic gaps is of particular importance in understanding the origin of bauxites. The main purpose of this investigation was to assess the geochemical contrast (aided by qualitative mineralogical analysis) among the several groups of Lower Paleogene bauxites previously defined in relation to their paleographical/paleotectonic settings and thus gain un understanding of the conditions and intervening processes prevailing on the emergent carbonate platform. A total of 50 bauxite samples of Lower Paleogene age were collected from various sites in Istria, on North Adriatic islands, in North Dalmatia and in Central Dalmatia and chemical and mineralogical analysis was performed on bulk samples. Multiple discrimination analysis (MDA) is a statistical technique that by maximizing between- group variance in comparison to the variance within each group is particularly useful when applied to distinguish between several pre- defined groups based on the great number of observations. Two discriminant function models (DFM) were created and four groups of bauxites have been neatly separated into their characteristic compartments according to specific combinations of major and trace elements. These models expound characteristic conditions and processes prevailing in the karst environment during subaerial exposure of the carbonate platform. In both models, the first discriminant function explains the most part of the system variability. The major-element DFM demonstrates a lower degree of separation between groups (86 %) with respect to the trace- element DFM (100 %) owing to the fact that major elements participate in a variety of processes during the sedimentary cycle, thus creating a mixed geochemical signal. Trace-element DFM proves itself as a more helpful predictive tool and more suitable for both discriminating and identifying purposes as the accumulation or depletion of trace elements usually narrows the scope of research to some particular segment of the cycle.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA