Naslov
Origin of Recent Organic-Rich Sediments from Morinje Bay (Northern Dalmatia, Croatia): Aspects of Hydrological and Hydrogeological Impact

Autori
Bačani, Andrea ; Koch, Georg ; Bergant, Stanislav ; Šparica, Marko ; Viličić, Damir ; Dolenec, Tadej ; Vreča, Polona ; Ibrahimpašić, Haris

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

Izvornik
Abstracts, Scientific Sessions, Part 2, 32nd International Geological Congress, Florence / - Firenza : München, 2004

Skup
32nd International Geological Congress

Mjesto i datum
Firenca, Italija, 20.08.2004. - 28.08.2004

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
hydrogeology; trophic level; palynofacies; organic-rich marine sediments; Morinje Bay; Croatia

Sažetak
Depositional history of Morinje Bay begun approximatively 4, 5ka B. P. as the Eocene carbonate-clastic basement ofMorinje depression was inindated by the sea ingression due to the ongoing Holocene sea-lebel rise. Morinje-Bay represents an restricted, shallow marine (<2m) environment characterised by varying seawater temperatures as well as fluctuating salinities caused by seasonally enhanced evaporation, continuous freshwater supply through onshore and submarine springs and surface runoff episodes. The freshwatersupply is associated with hydrology and karst-hydrology of the wider area of Morinje Bay. The major amount of the fresh water flows into the Bay by the Dabar stream with a catchment area of103km2.The Dabar is the torrential stream with maximum 5-year discharge of 46 m3/s. Coastal onshore springs and offshore springs significantly contribute to the fresh water inflow. Their yields depend on hydrological conditions ; however, some of them never dry out. Withinthe Morinje Bay environment, organic-rich deposits accumulate mostly as clayey-sandy silts. Palynological and D13C composition shows that the sedimentary organic matter consists on average of 2/3 marine and 1/3 terrestrial organic matter. Palynofacies of the sediments is dominated by amorphous organic matter (AOM) which is mostly derived from phytoplankton, bacteria and marine macrophytes. Frequent framboidal pyrite inclusions within the lipid-rich AOM as well as the measurements of the Eh and Ph indicate oxygen-depleted depositional conditions at a sedimentation rate approximately 1m/1ka. High organic matter content of the sediments, mostly AOM, suggests enhanced primary bioproduction, i. e. eutrophic conditions of the Morinje Bay ecosystem. An important indicator of primary bioproduction is the quantity of phytoplankton which is controlled by a combination of ecological factors (supply and concentration of nutrients, thermohaline relations, light). These factors are significantly influenced by the karst hydrology and hydrogeology. This is well examplefied in Morinje Bay where the phytoplankton activity measured durin April and June fits with the pattern of an naturally eutrophicated ecosystem. The hydrological and hydrogeological impact on the trophic level, i. e. enhanced primary bioproduction, has been recently recorded also within similarRecent ecosystems along the Croatian coast where organic-rich sediments accumulate.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Rudarstvo, nafta i geološko inženjerstvo

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