Abstract Carbon isotope composition of dissolved inorganic carbon (DIC) was studied at springs, lakes and tributaries of the Plitvice Lakes. The Plitvice Lakes are a unique and complex karst lakes system consisting of 16 flow-through lakes connected by waterfalls and streams and characterized by intense calcium carbonate precipitation in the form of tufa and lake sediments. Two main springs have different 14 C concentrations due to different geology and their variations were controlled by flow rates. Further downstream, at lakes to the Korana River that outflows from the lakes, the 14 C activity and δ 13 C consistently increased down the flow. Carbon isotope composition from 2010 to 2015 was compared with the values measured 30 years earlier. The variation in δ 13 C DIC was accounted for seasonal change, while 14 C activity of surface water DIC decreased 7–12% during the 30 years. Using a semi-empiric model, it is calculated that the downstream increase is controlled by the exchange of DIC and atmospheric CO 2 carbon and by introduction of decomposed biogenic carbon from the top soil organic matter of the lakes surrounding area in almost equal proportions.

ABSTRACT The Cretaceous-Paleocene (K/P) boundary intervals are rarely preserved in successions of shallow-water limestones. Here, we describe a shallow rocky shore on the active orogenic wedge of the eastern Alps (Austria) fringed by a carbonate platform that was largely cannibalized by erosion. We compared this succession with similar nearshore environments globally, as well as the deep sea, to gain a better understanding of the environmental response to the K/P boundary transition. In the eastern Alps, Cretaceous and Paleocene lithofacies across the K/P boundary transition are separated by a hardground that formed during subaerial exposure and that terminates Upper Maastrichtian limestone with planktic foraminiferal assemblages deposited at neritic depth during zone CF3 (ca. 66.500 Ma). Above the hardground, there are beachrocks with early Danian zone P1a(1) assemblages, which indicate the hardground spans about ~600 k.y. of nondeposition and/or erosion. During the early Danian, the marine transgressive fringe fluctuated between “shoreface to emersion” environments, depositing limestones rich in bryozoans, rhynchonellids, coralline algae, and rare planktic foraminifera along with abraded, bored, and/or encrusted clasts eroded from older rocks. Repeated short subaerial exposure is marked by vadose diagenesis and hardgrounds, including an ~1.5 m.y. interval between magnetochrons C29n to C28n and planktic foraminiferal zones P1b to P1c(2). Comparison with platform carbonate sequences from Croatia, Oman, Madagascar, Belize, and Guatemala, as well as nearshore siliciclastic environments of southern Tunisia, Texas, and Argentina, across the K/P boundary transition revealed surprisingly similar deposition and erosion patterns, with the latter correlative with sea-level falls and repeated subaerial exposure forming hardgrounds. Comparison with deep-sea depositional patterns revealed coeval but shorter intervals of erosion. This pattern shows a uniform response to the K/P boundary transition linked to climate and sea-level changes, whether in shallow nearshore or deep-sea environments, with climate change tied to Deccan volcanism in magnetochrons C29r-C29n.

ABSTRACT An unusual deposit at the Cretaceous-Paleogene (K-Pg) boundary within the Adriatic carbonate platform shallow-water succession is interpreted as a major tsunamite, and a possible mechanism that links it to the Chicxulub asteroid impact on Yucatan (Mexico) is speculated. Although the K-Pg boundary hiatus is a common feature within the shallow-marine successions of the Adriatic carbonate platform, three exceptional sections were discovered that are characterized by continuous sedimentation and the event beds at the K-Pg boundary. Two sections include ~5-m-thick coarse-grained complex event beds intercalated within more than 100-m-thick successions of predominantly micritic carbonates deposited in the protected low-energy inner-platform setting, relatively proximal to the platform-margin embayments. The third section is characterized by an ~10-cm-thick event bed showing distinct soft-sediment bioturbation, and it is interpreted as a more distal section. It has been reported previously that the Chicxulub impact cratering generated an almost global tsunami, while the seismic waves caused collapses of the North American southeastern margins. It is hypothesized that the collapses could have generated a megatsunami in the Atlantic Ocean that could pass through a deep seaway between the Atlantic and western Tethys Oceans and finally terminate on the Adriatic carbonate platform, located ~10,000 km from the impact site. Considering the fact that there are potential sedimentological indications for such a huge sedimentary event in NW Africa (Morocco), focused research is needed in the region, along with landslide tsunami modeling, for a relevant evaluation of the hypothesis.

ABSTRACT An ~10-m-thick sequence of Quaternary eolian sands from the island of Vis (Croatia) was investigated with the aim to unravel and understand their origin, characteristics, and age. The sand deposit is situated in a karstic depression in the eastern part of the island at an altitude of ~100 m above sea level (a.s.l.), and it is composed of a subhorizontally laminated unit at the bottom underlying a cross-bedded unit. The sand is very well sorted and fine grained and composed predominantly of carbonate lithic fragments, which most likely originated from the Dinaric karst region. The siliciclastic component of these sands reflects a more complex lithological source, including older sedimentary (e.g., flysch successions in the area, as well as older Quaternary deposits), magmatic, and metamorphic rocks probably originating from the Inner Dinarides, which were eroded and comminuted by glacial and periglacial activity during the last glacial period, and transported toward the Adriatic foreland by major rivers such as the Cetina and Neretva. Grain size and shape characteristics of the sands as well as their sedimentary structure indicate their eolian origin. Optically stimulated luminescence (OSL) dating was applied to determine the depositional age of the sediment. The obtained ages can be correlated to the Last Glacial Maximum (oxygen isotope stage [OIS] 2), implying that during the peak of that glaciation, the central Adriatic basin was dry land, a vast plain exposed to eolian deflation.

ABSTRACT We present the results of a compositional characterization study of amphorae from the ancient Greek town of Pharos, today Stari Grad, on the island of Hvar, in central Dalmatia, Croatia. The aim of the study was to identify the provenance of amphorae unearthed in Pharos, to determine the locally produced amphorae, and to identify the provenance of imported amphorae with a scientific-based approach, using optical thin-section petrography and bulk geochemical analysis by wavelength-dispersive X-ray fluorescence on 19 samples of different types of amphorae and reference materials. The results of the analyses allowed us to identify a group of imported amphorae from Corinth or Corfu and a group of imported amphorae from southern Italy, probably from Calabria. We were also able to identify a third group of imported amphorae from an as-yet-unknown provenance/workshop. Finally, according to the geochemical composition and close match with the reference material, namely, kitchenware, only two amphorae from the examined collection could be identified as local products. The results of the compositional characterization of amphorae from Pharos show us that an ancient Greek town had trade contacts beyond the Adriatic-Ionian region, and they provide opportunities for further studies of ancient amphorae production and circulation in this part of the Mediterranean.

ABSTRACT In this paper, we review ~140 yr of investigations about pelagosite, a usually black aragonitic encrustation with a vitreous luster that forms in the splash zone of Mediterranean rocky coasts. Prior to the mid-1920s, the geologic community considered pelagosite to be a separate mineral of uncertain composition, but then in 1926, Italian mineralogist Ettore Onorato determined that pelagosite has the same structure as aragonite (orthorhombic CaCO 3 ), and also that it contained cells of blue-green algae (i.e., cyanobacteria). Once pelagosite was declassed from the status of a mineral, and its name was eliminated from catalogues and textbooks, Onorato’s documentation of the cyanobacterial cells contained in this encrustation seems to have fallen into almost total oblivion during the rest of the twentieth century. We revisited pelagosite in its original type locality, the remote southern Adriatic island of Pelagosa (today’s Croatian island of Palagruža), as well as in the Dalmatian island of Hvar. Using modern analytical methods and techniques, we redefined the mineralogical and geochemical composition of pelagosite, the nature and significance of its microbial content, and the origin of its pisolitic “tree-ring” internal structure, which probably reflects cyclic climate changes.

Abstract A strong and potentially dangerous decreasing trend in the level of water in Vrana Lake over the last three decades was analysed. This freshwater lake is a unique karst hydrology feature located on the small Adriatic island of Cres (405.71 km 2 ), which is entirely composed of carbonate rocks. The lake is situated in a large cryptodepression and its base reaches a depth of 61.3 m below mean sea-level. The lake is a complex hydrological–hydrogeological system with an average water volume of c. 220 × 10 6 m 3 . The larger geographical region has been affected by an increase in air temperature over the last c. 40 years. This exceptionally clean freshwater lake is the only source of potable water for the whole Cres archipelago. A dangerous drop in the water level of the lake started in 1983. This decreasing trend is driven by both global climate change and anthropogenic (the overexploitation of water) factors.