Naslov
Geochronology and evolution of tufa deposits at Roški Slap in Krka National Park, Croatia

Autori
Dominguez-Villar, David ; Krklec, Kristina ; Cukrov, Neven ; Cheng, Hai ; Edwards, Lawrence R.

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

Izvornik
XIX INQUA Congress 2015 Quaternary Perspectives on Climate Change, Natural Hazards and Civilization / - Nagoya : International Union for Quaternary Research (INQUA), 2015

Skup
XIX INQUA Congress 2015 Quaternary Perspectives on Climate Change, Natural Hazards and Civilization

Mjesto i datum
Nagoya, Japan, 26.07.2015. - 02.08.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
tufa ; Krka ; geochronology ; Roški slap

Sažetak
Roški Slap is one of the key scene sites within the Park due to its impressive active tufa barrage system within a canyon. Ancient tufa sediments are preserved in the canyon walls, having a total height of 22.5 m over the current river level (m c.r.l.). The cascade facies of these sediments suggest the existence of a barrier-lake tufa system (B-LS). A large block of this deposit (1.5-13.5 m c.r.l.) collapsed at some point as a result of the erosion of the B-LS. Between the block and the canyon wall there is a mamelar tufa. This is a typical facies of tufa bearing lakes and represents the formation of a 2nd B-LS slightly downstream, with a lake at least 7 m in depth and sediments reaching a minimum height of 8.5 m c.r.l. We used U-Th to establish the chronology of these ancient tufas and try unravelling how much time took to erode the 1st B-LS. Four dates from the 1st B-LS provided dates from 123 to 130 ka BP with uncertainties ranging from 0.9 to 1.3 ka. Eight dates from the 2nd B-LS provided dates from 122 to 130 ka BP with uncertainties ranging from 2.3 to 3.8 ka. The 230Th/232Th activity ratios of 11 to 88 suggest that true ages might be slightly younger than the dates here reported. However, the initial 230Th correction of dates using the isochron method does not provide better chronologies since at least two sources of 232Th might be present. Despite a limited uncertainty in the accuracy, we can conclude that both phases of B-LS were deposited during the Last Interglacial Period. Our dating uncertainty is large enough to prevent us differentiating the ages of these two ancient tufa systems, suggesting a relatively fast erosion episode between both of them.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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