13 research outputs found

    Cenomanian–Turonian Oceanic Anoxic Event (OAE2) Imprint on the Northwestern part of the Adriatic Carbonate Platform and a Coeval Intra-Platform Basin (Istria and Premuda Island, Croatia)

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    The Cenomanian–Turonian boundary (CTB) on the intra-Tethyan Adriatic Carbonate Platform (AdCP) is generally characterised by a transition between microbially laminated and/or bioclastic limestones to calcisphere-rich massive limestone with bioturbated intervals, organic-rich interbeds, firmgrounds, as well as neptunian dikes, carbonate turbidites, tempestites and slumped structures. Compilation of the results from two study sites in the northwestern part of the AdCP and from previous research (on Istria Peninsula and islands in the Adriatic Sea in Croatia) provides a more complete overview of geological events and paleoenvironmental conditions that transformed the formerly contiguous shallow-marine environments during this time period. For the first time, a comparison between protected inner-platform area (Barban section) and a coeval intra-platform basin (Premuda Island section) during the CTB was made. This study utilized a combination of litho-, bio-, and microfacies studies with SEM, EDS, TOC, δ13C and δ18O stable isotope analyses. The stratigraphic successions start with shallow-marine carbonate deposits of the Milna Formation that is conformably overlain by the drowned-platform deposits of the Sveti Duh Formation on the platform and by the Veli Rat Formation in the contemporaneously developed intraplatform basin. These deposits are in turn overlain by the Gornji Humac Formation, which represents re-establishment of shallow-marine depositional systems on the AdCP, whereas the deeper water environment persisted in the intra-platform basin until the Santonian. Despite diagenetic modifications of shallow-marine carbonate deposits, the results of TOC and stable isotope analyses indicate the influence of global Oceanic Anoxic Event 2 (OAE2). Combination of local and regional synsedimentary tectonics and global Late Cretaceous sea-level changes accompanied by anoxic and hypoxic conditions, extinction of numerous benthic foraminifera, diversification and expansion of planktonic foraminifera and calcareous dinoflagellates, provide new insights into the character of the CTB interval in this part of the Tethyan realm

    Geochemistry and organic carbon data of sediment cores from Veliko jezero, Mljet, Croatia

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    To investigate the sediments deposited in the lake that was flooded due to Holocene sea level rise, two cores were sampled. Length of the cores is 459 cm (M1-A) and 407 cm (M2). Semi-quantitative geochemistry of the cores was determined by XRF core scanner in 1 cm resolution for both cores and 2 mm resolution, in the interval from 114-242 cm, for M1-A core. Additionally, total organic carbon and nitrogen were analyzed in 1 cm resolution in M1-A core in interval from 114-237 cm, while δ13C was determined in 10 cm resolution from 5 - 459 cm. Furthermore, semi-quantitative X-ray diffraction was done in 3 cm interval from 114-239 cm in M1-A core. Research was done on the eastern Adriatic coast on the Island of Mljet, Croatia, in marine lake Veliko jezero. Veliko Jezero is a submerged doline

    Vegetation History in Central Croatia from ~10,000 Cal BC to the Beginning of Common Era—Filling the Palaeoecological Gap for the Western Part of South-Eastern Europe (Western Balkans)

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    The aim of this study was to reconstruct the vegetation changes, fire history and local landscape dynamics of central Croatia (the western part of south-eastern Europe) from 9800 cal yr BP to the beginning of the Common Era. Pollen, non-pollen palynomorphs and charcoal were analysed for the first time in the aforementioned area by modern palynological methods. Three different assemblage (sub)zones were identified: “Pinus-Fagus-Quercetum mixtum” (Preboreal), “Fagus-Corylus” (Boreal) and “Alnus-Fagus” (Atlantic, Subboreal and older Subatlantic). Additionally, the oldest observation (~9800 cal yr BP) of beech pollen for continental Croatia was confirmed by radiocarbon dating. Our results indicated a possibly milder climate with less extreme temperatures and higher precipitation during the Preboreal chronozone, alongside intensive flooding, a transition from a mosaic of wetland/wet grassland communities to alder carr during the Boreal, and an unusually long multi-thousand-year period, the annual presence of alder on the mire itself. An increase in the number of secondary anthropogenic indicators can be tracked from the 6th century BC to the beginning of the Common Era. Although regional vegetation changes are insufficiently clear, our results fill a gap in the interpretation of vegetation/palaeoenvironmental changes before the Common Era in in this part of Europe
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