Naslov
Microfacies and sedimentary environment of the lacustrine Island Pag Basin (Early Miocene, S Croatia)

Autori
Vranjković, Alan ; Gierlowski-Kordesch, Elisabeth ; Dragičević, Ivan ; Jakupec, Ema ; Pavelić, Davor ; Mandic, Oleg ; Harzhauser, Mathias ; Šegvić, Branimir ; Brčić, Vlatko ; de Leeuw, Arjan

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

Izvornik
Sedimentology at the crossroads of new frontiers ; Abstracts Book / - Ženeva, 2014, 723-723

Skup
19th International Sedimentological Congress ;

Mjesto i datum
Ženeva, Švicarska, 18.08.2014. - 22.08.2014

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Donji miocen; Paški bazen; jezerski karbonati
(Early Miocene; Islan Pag basin; lacustrine caronates)

Sažetak
The Island Pag Miocene succession represents the infill of the northwestern-most basin of the Neogene Dinaride Lake System (DLS). In the beginning of the Early Miocene, a series of extensional depressions were formed on the uplifted Dinaride mountain range. Faulting triggered erosion of the nearby uplifted Mesozoic-Paleogene carbonates and the formation of numerous, synchronous, carbonate-rich, shallow lacustrine basins in these depressions. The Island Pag Miocene Basin infill was logged in detail along Crnika beach. The section is located on the SW shore of Pag Bay, where outcrops over a lateral distance of nearly one kilometer are present. Paleomagnetic measurements of the Crnika section combined with biostratigraphic constraints based on mollusks and the pollen record indicate that the Pag succession was deposited between 17.1 and 16.7 Ma (Burdigalian stage of the Mediterranean ; Karpatian stage of the Central Paratethys), i.e. in the period of the Miocene Climatic Optimum (MCO ; ~17 to ~15 Ma). The Crnika section represents about a 140-meter-thick record of lacustrine deposits. The rest of the exposure contains Quaternary breccias, sandstones and clays. Sedimentological analysis and petrography of the Miocene lacustrine carbonates distinguishes five microfacies described as follows (A) Micritic mudstones comprised of very fine-grained, degraded, and/or carbonized plant remains randomly distributed throughout. (B) Charophyte biomicrite composed of micritic packstone-wackestones containing complete or silt-sized fragmented plant material (mostly stems of submerged vegetation) encrusted with carbonate with finely dispersed siliciclastic quartz grains. (C) Sandy micrite comprised of 65% micrite with 35% fine sand-sized quartz and carbonate grains dispersed randomly throughout the micrite. (D) Calcisiltite containing quartz grains in a calcitic-clayey matrix. (E) Cyanoid grainstone containing oncolites up to a few mm in diameter within a carbonate mud supported fabric with dispersed microsparite. Microfacies analysis reveals that sediment deposition in the Miocene Pag lake was dominantly in the form of authigenic lime mud induced by the photosynthetic activity of floating and submerged macrophytes as well as charophytes, algae, and possible microbes. Rooted submerged macrophytes indicate a vegetated littoral zone. Vertical microfacies patterns point to carbonate sedimentation on broad shallow, low-energy bench lake margin in one progradational regressive cycle. Lacustrine carbonates are interbedded with penecontaporaneous carbonate and siliciclastic material and coal, suggesting an overfilled lacustrine system. Tectonics and climate worked in tandem having controlled the subsidence along with the sediment and water input.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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