Naslov
Organic Petrology and Geochemistry of the Jurassic Carbonates of the Karst Dinarides (Croatia)

Autori
Troskot-Čorbić, Tamara ; Španić, Darko ; Rumenjak, LJubica ; Maričić, Marija ; Stanković, Irenka

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

Izvornik
57th Annual Meeting of the International Committee for Coal and Organic Petrology, Abstracts Book / - Patras : University of Patras, 2005, 48-48

Skup
57th Annual Meeting of the International Committee for Coal and Organic Petrology

Mjesto i datum
Patras, Grčka, 18.09.2005. - 23.09.2005

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Dinarides, Jurassic, organic petrology

Sažetak
Platform carbonate deposits of the Karst Dinarides area have a stratigraphic range from the Middle Triassic (or even Carboniferous in some places) to the Middle Eocene, forming a belt nearly 700 km long and, (after reduction by younger tectonics) 80–210 km wide. Besides their significant thickness, they are characterised by frequent lateral and vertical alternations of different facies, mostly associated with different shallow marine environments but there are also carbonate slope deposits and those representing temporarily drowned platform facies and intraplatform troughs. The Jurassic part of this carbonate succession has been subdivided into 9 megafacies units (Tišljar et al., 2002). Megafacies of mudstones and wackestones deposited in lagoon and subtidal and/or isolated and restricted lagoon/deeper subtidal areas of the inner platform (lias, dogger, malm) as well as megafacies of “limestones with cherts”, deposited within intraplatform troughs with temporary or continuous connection to the open sea (malm) are the objective of this study in a sense of detailed geochemical characterization of types of organic matter and their genetic correlation. Laminated and fine-grained limestones that contain autochthonous organic matter (kerogen and associated bitumen) as well as dolomites and limestones with pores, fissures and cavities filled with migrated bitumen were collected from localities in the wider area of Velika Kapela Mt. and from “Lemeš trough” that stretches from the vicinity of Bihać in NW Bosnia towards the south into E Lika and N Dalmatia, where Jurassic intraplatform trough were formed. The results of the analyses show the presence of the kerogen type I-II in organic-rich laminated limestones, which means, the samples investigated are considered as source rocks of very high generative potential. According to microsolubility and strong yellow to yellow-orange fluorescence effect, organic matter is mixture of algal, bacterially degraded kerogen and migrated bitumen. Bitumen reflectance is from 0.20 to 0.30 % Ro. Generally, organic matter is in diagenetic stage of thermal transformation or reaches onset of oil generation. High percentages of organic bonded sulphur are evidence that organic matter formation was in marine, carbonate environment with contemporaneously sulphur incorporation in a kerogen macromolecule structure. This kind of organic facies enabled hydrocarbon generation at lower degree of thermal transformation. High degree of similarity of source rock extracts and bitumens or bituminous coatings indicates short migration phenomena.

Izvorni jezik
Engleski

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