Naslov
Late Quaternary sedimentological and geomorphological processes in the Prološko Blato karst polje (Imotsko polje, Croatia)

Autori
Ivkić Filipović, Ivona ; Ilijanić, Nikolina ; Miko, Slobodan ; Hajek Tadesse, Valentina ; Hasan, Ozren ; Kordić, Branko

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

Izvornik
Book of abstracts / Jamšek Rupnik, Petra ; Novak, Ana - Ljubljana : Geološki zavod Slovenije, 2021, 44-44

Skup
6th Regional Meeting on Quaternary Geology: Seas, Lakes and Rivers

Mjesto i datum
Ljubljana, Slovenija, 27.09.2021. - 30.09.2021

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
karst lakes, karst poljes, lake sediments, Holocene

Sažetak
Prološko Blato is a karst wetland situated in the NW part of the Imotsko polje (Dalmatian hinterland). It is a typical example of Dinaric karst polje, with many hydrogeological and geomorphological features such as lakes, springs, estavelles, making it suitable for multidisciplinary paleolimnological research. We conducted percussion drilling in the polje and geophysical survey (GPR, geoacoustics), supported with aerial photogrammetry, to determine the paleoenvironmental conditions, geomorphological and hydrological changes from the Late Pleistocene through the Holocene. Two sediment cores (6, 5 m and 9, 2 m long) were analyzed by multiproxy approach (sedimentology, mineralogy, geochemistry, micropaleontology) and radiocarbon dating, to determine the time-span of the lake sediments and timing of significant sedimentary changes. Results show that the Last Glacial Period (from ~30 ka cal yr BP to the Early Holocene) is marked by sedimentation of fluvial and possibly fluvioglacial material, that was transported from the mountainous area of western Herzegovina (elevations greater than 2000 m) into the karst polje depression. Numerous dolines (sinkholes) distributed along the NW part of the polje served as depocenters for sedimentary material, while the morphology of these dolines implies their relatively young age of formation and active karstification processes. The Early Holocene (9, 3 - 8 ka cal yr BP) is characterized with siliciclastic sedimentation in an „early lake“ environment of the Prološko Blato, while the Early-Late Holocene (8 – 0, 8 ka yr BP) is marked by the lake deepening and authigenic carbonate sedimentation of lake marl, rich in ostracods, gastropods, and Charophytes. A distinctive lithological change in sedimentation occured at approximately 800 cal yr BP, from lake marl to greyish-brown clay, associated with transition from lacustrine to floodplain environment. Most probably, it is caused by the formation of the Prološko Lake in the eastern part of the Prološko Blato, associated with dissolution processes of limestones, and roof collapsing into an underground cavern, similar to the famous collapse dolines Red Lake and Blue Lake near the city of Imotski. This event corresponds to the well-known period of significant seismic activity in the Dinarides between 1000 and 1200 yr AD. The Imotski region is a seismically very active region, where earthquakes and their primary and secondary effects are historically well documented. The „collapse“ hypothesis is investigated by the paleolimnological research methods since we identified several historical and geomorphological evidence of collapse doline formation, usually after a stronger earthquake (M>5). Final results will contribute to our understanding of the geomorphological and sedimentological processes in the high karst zone of the Dinarides and will give us an insight into the timing and circumstances of the formation of karst lakes in the NW part of the Imotsko Polje.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA