Naslov
Lake Vrana (the Island of Cres) paleolimnology during the Late Pleistocene/Holocene

Autori
Ilijanić, Nikolina ; Miko, Slobodan ; Hasan, Ozren ; Bakrač, Koraljka ; Hajek Tadesse, Valentina ; Galović, Ines

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

Izvornik
5. HRVATSKI GEOLOŠKI KONGRES s međunarodnim sudjelovanjem/5th CROATIAN GEOLOGICAL CONGRESS with international participation Osijek 23.– 25.09.2015. Knjiga Sažetaka/Abstracts Book / Marija Horvat & Lara Wacha - Zagreb : Hrvatski geološki institut, 2015, 114-114

ISBN
978-953-6907-50-2

Skup
5. HRVATSKI GEOLOŠKI KONGRES s međunarodnim sudjelovanjem/5th CROATIAN GEOLOGICAL CONGRESS with international participation

Mjesto i datum
Osijek, Hrvatska, 23.09.2015. - 25.09.2015

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Domaća recenzija

Ključne riječi
paleolimnology; lake level; vegetation history; mineralogy; geochemistry; Late Pleistocene/Holocene; Lake Vrana (Cres)

Sažetak
Paleolimnology uses multidisciplinary approach in research of lake sediment sequences, in order to define paleoenvironmental characteristics. The paleolimnological research of Vrana Lake on the island of Cres is based on one core from the central part of the lake and additional 3 cores from the shallower northern part of the lake. Color and magnetic susceptibility analysis, grain size, mineralogical and geochemical analyisis, so as palyinological, ostracod and diatom analysis on selected sediment cores were carried out. Reconstruction of the paleoenvironmental conditions through Pleistocene and Holocene (the last 15, 000 years) was done based on the sediment core from the central part of the Lake Vrana, while the cores from the shallower northern part were used to reconstruct lake level in the last 5, 000 years. The deepest sediments (6-7 m), where the dates were beyond the limit of the radiocarbon dating, show high dolomite content and clay minerals are represented by chlorite, hydroxyl interlayered vermiculite, illite and kaolinite, which reflects terra rossa soils as their source. From 5 to 3.85 m the sediments contain higher amount of calcite and dolomite, while in clay minerals fraction appears smectite, which is present in loess material in the catchment. Siliciclastic material is dominant in the lake sediments from 3.85 to 2.95 m (14.5-11.5 ka cal BP), with interruption interval from 3.45-3.30 m, which could be hiatus in sedimentation. The beginning of the Holocene (2.95 m) is characterized by the deposition of siliciclastic material (higher values of Al and other detrital elements, quartz and feldspars recorded in sediments), which is continued into the middle Holocene, until 4.5 ka cal BP (1.25 m). From that period dominant carbonate sedimentation is observed and it can be presumed that the deeper lake has been established. Magnetic susceptibility is very high in periods around 8-7.5 ka cal BP (1.90- 1.80 cm) and 7.2-6.6 ka cal BP (1.75-1.64 m), which is in the Adriatic basin defined as the maximum of the summer precipitation, indicating erosion of the siliciclastic material from the catchment (Combourieu Nebout et al., 2013). Pollen analysis has determined the establishment of the Mediterranean vegetation holm oak forests and degradation stage of holm oak trees (macchia) in Lake Vrana between 8 and 7 ka cal BP (Schmidt et al., 2000). From 4.5 ka cal BP until present wet period is observed and from the last 300 years there is increased erosion in the basin, with higher amount of detrital material. Higher values of the lightness parameter of the sediments in the cores from the northern part of the lake indicate that the higher lake level period was established after 4.5 ka cal BP.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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