Naslov
Holocene evolution of the delta plain of Neretva River (Croatia) and its potential for reconstructing the relative sea-level changes

Autori
Fontana, ALessandro ; Felja, Igor ; Juračić, Mladen ; Rossato, Sandro ; Mazzini, Ilaria

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

Izvornik
6th Regional Scientific Meeting on Quaternary Geology: Seas, Lakes and Rivers Ljubljana, 27–29 September 2021 Book of abstracts E-book © 2021, Geološki zavod Sovenije, Ljubljana / Petra Jamšek Rupnik, Ana Novak - Ljubljana, 2021, 22-23

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

Mjesto i datum
Ljubljana, Slovenija, 27.09.2021. - 29.09.2021

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Holocene, Neretva River, Adriatic, sea-level changes, delta

Sažetak
Neretva River developed the largest delta plain along the Istrian and Dalmatian coast and this evolution has been favoured by the wide mountain basin of the river and the occurrence in the upper part of the catchment of siliciclastic rocks. This setting allowed the sedimentary supply of the fluvial system and permitted a Holocene progradation of about 15 km along the final sector of the Neretva river valley. The aim of this research is to describe the succession of depositional facies which developed during Holocene in a sector of the Neretva River delta plain. A main goal is to collect and assess the availability of high-quality index points for reconstructing past Relative Sea Level (RSL), selecting a protected site where the direct action of marine waves had not been felt and the coastal deposits directly sedimented over the bedrock. For this purpose, sedimentological, chronological and paleontological features of two adjacent sediment cores were analysed, sampling the Holocene sequence in the wetlands near Opuzen and reaching the Mesozoic substrate. The paleontological investigations analysed the foraminifera, ostracoda and mollusc associations, mainly consisting of benthic foraminifera and ostracods, that are abundant microorganisms in shallow and marginal-marine environments and are widely applied in the analysis of Holocene sea- level changes and in paleoenvironmental reconstructions of estuarine systems. The research is also supported by the analyses of grain size, radiocarbon and carbonate content. The vertical markers of the RSL have been described with a standardized methodology, following the recent IGCP protocol developed for creating database of past sea-level index points (e.g. Vacchi et al., 2016). Here we present the results related to the cores NER5 and NER6, which were drilled 5 m a part one form the other along the flank of a limestone hill, up to found the bedrock, and they reached 4.9 and 8.2 m of depth, respectively. The base of sediments on top of the limestone bedrock is dating to 3.2 cal BP and its meaning is that sediment started to arrive in that moment, while before the area was already submerged by the sea, but there were no favourable conditions to record the paleo-environment. The combined use of sedimentological and paleontological analyses of two sediment cores and 14C dating allowed recognizing different depositional environments and their succession in the marginal part of the Neretva delta plain during Holocene highstand. These interpretations permit to reconstructing sea-level and give some constraining features for documenting the evolution of Neretva delta area in the last 3000 years. The top portion of both cores, from 3.2 m of depth in NER6, consists of paludal deposits that are representative of the moment in which Neretva River passed the threshold of Opuzen and blocked the outflow of the fresh water coming from the tributary valleys and created a freshwater swamp/ lacustrine environment. Since that moment that is dated about 100-200 AD the situation has been remained almost stable. In both cores, before anthropogenic deposition on top (last 100-200 years) there was only accumulation of plant remains.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Interdisciplinarne prirodne znanosti

POVEZANOST RADA