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We report the discovery of an important new cryptotephra within marine sediments close to Cape Hallett (northern Victoria Land), in the western Ross Sea, Antarctica. The cryptotephra is fully characterized for its texture, mineralogy and major- and trace-element data obtained on single glass shards. On the basis of geochemical composition, the cryptotephra is unequivocally correlated with the proximal deposits of an explosive eruption of the poorly known Mount Rittmann volcano, situated in northern Victoria Land. The cryptotephra is also correlated with a widespread tephra layer, which was erupted in 1254 C.E. and is present in numerous ice-cores and blue ice fields across East and West Antarctica. The characteristics of the tephra indicate that it was produced by a prolonged, moderate energy, mostly hydromagmatic eruption. This is the first time that a cryptotephra has been identified in marine sediments of the Ross Sea and in ice cores. It provides an important new and widespread stratigraphical datum with which the continental cryosphere and marine sedimentological records in Antarctica can be correlated. Moreover, from a purely volcanological point of view, the discovery further confirms the occurrence of a long-lasting, significant explosive eruption from Mount Rittmann in historical times that produced abundant widely dispersed fine ash. The study also highlights the inadequacy of current hazard assessments for poorly known volcanoes such as Mount Rittmann, located at high southern latitudes.

In the framework of geosite management, specific targeted symbols for geomorphological legends are still lacking. Concerning geosites of geomorphological interest, geomorphological mapping requires targeted symbols in relation to goals and applications, either concerning geomorphic hazards and risk detection or the enhancement of resources, in particular those related to cultural heritage and, hence, geoheritage. A new methodology for mapping geo(morpho)heritage on geomorphological maps is presented in this paper. Nine iconic examples from the Italian landscape, selected in different morphogenetic and morphoclimatic contexts, are proposed to test the methodology in relation to point, polyline and polygon features. Moreover, guidelines for mapping are suggested according to the importance of the site and to the complexity of processes characterizing each case study.

Time-series analyses of satellite images reveal that sea ice extent in the Ross Sea has experienced significant changes over the last 40 years, likely triggered by large-scale atmospheric anomalies. However, resolving how sea ice in the Ross Sea has changed over longer timeframes has until now remained more elusive. Here we used a laminated sediment piston core (14.6 m) collected from the Edisto inlet (Western Ross Sea) to reconstruct fast ice dynamics over the last 2.6 ka. Our goal was to first understand the climate expression of selected well-defined sediment laminae and then use these characteristics for reconstructing past sea ice behaviour across the whole sedimentary sequence. We used the recently established sea ice diatom biomarker proxy IPSO25 in combination with diatom census counts and bulk analyses. Analyses performed on a suite of discrete laminae revealed statistically significant differences between dark and light laminae reflecting different depositional conditions. Based on their respective biogeochemical fingerprints, we infer that dark laminae accumulated during sea ice thaws in early summer. Under these conditions, laminae contain relatively high concentrations of IPSO25 and display an enriched delta C-13 composition for the bulk organic matter (OM). While diatom assemblages in dark laminae are relatively homogenous, as the thaw continues later in the summer, Corethron pennatum becomes the dominant diatom species, resulting in the formation of light laminae characterized by low IPSO25 concentrations. Since C. pennatum can migrate vertically through the water column to uptake nutrients and avoid competition in oligotrophic waters, its high concentration likely reflects stratified and ice-free surface waters typical of late summer. Down-core trends show that the correlation between sediment brightness and geochemical fingerprint (i.e., IPSO25 and delta C-13) holds throughout the record. Based on the knowledge gained at lamina level, our down-core high-resolution reconstruction shows that the summer fast ice coverage changed dramatically during the late Holocene. Specifically, we conclude that the Edisto inlet experienced regular early summer opening between 2.6 ka, and ca. 0.7 ka, after which, coastal fast ice persisted during summer months and ice-free conditions became less frequent. Comparison with previous regional ice core data suggests that the sudden cooling recorded over the Victoria Land Coast region since 0.7 ka might potentially explain our observation of persistent summer fast ice in the Western Ross Sea. Our study has shown that multi-proxy data derived from laminated sediments can provide hitherto unknown detail regarding past summer sea ice dynamics in coastal Antarctic regions. (C) 2020 Elsevier Ltd. All rights reserved.

Alle pendici del Pic Chiadenis (alpi Carniche, Udine) si apre una cavità (4846/2714FR) nelle quale è stato individuato un signifcativo deposito di ghiaccio che, sulla base delle analisi effettuate, risulta essersi formato tra gli anni sessanta e gli anni ottanta del secolo scorso e che ormai è quasi del tutto scomparso. La grotta ha fornito anche indizi di neotettonica e presenze di mineralizzazioni aragonitiche: per tutti questi aspetti la cavità potrebbe essere utilizzata come "laboratorio sotterraneo naturlae" ai fini dello studio applicato del carsismo di alta quota.

Paleoclimatic and paleoenvironmental reconstruction during the last 2ka using geochemical and biological proxies in marine sediments from western Ross Sea (Antarctica)

Classical karst near Trieste is the worldwide symbol of karst processes. However there are very few trails dedicated to promote and henance geological and geomorphological heritage. So we propose a trail in an area with full example of the most important epigean karst phenomena.

Around 20–25% of the Friuli Venezia Giulia region consists of karstified rocks. The geological, geographical and climatic conditions have given rise to a whole series of karst landscapes which have developed in different ways on limestone of different ages, located at different altitudes. One encounters splendid examples of alpine karst (Mt. Canin and Cansiglio–Cavallo Massif), mountain-hill karst (Mt. Ciaurlec, Julian Prealps) and marine-coastal karst. In the Classical Karst near Trieste, the worldwide symbol of karst phenomena, over 3000 caves are known while half a dozen are over 1000 m in length. There are about 80 solution and collapse dolines with a diameter greater than 100 m.

A marine sediment core collected from the Nordenskjold Basin, to the south of the Drygalski Ice Tongue, provides new sedimentological and chronological data for reconstructing the Pleistocene glacial history and palaeoenvironmental evolution of Victoria Land. The core consists of an over consolidated biogenic mud covered with glacial diamicton; Holocene diatomaceous mud lies on top of the sequence. Radiocarbon dates of the acid insoluble organic matter indicate a pre-Last Glacial Maximum age (>24kyr) for the biogenic mud at the base of the sequence. From this we can presume that at least this portion of the western Ross Sea was deglaciated during Marine Isotope Stage 3 and enjoyed open marine conditions. Our results are consistent with recent findings of pre-Holocene raised beaches at Cape Ross and in the Terra Nova Bay area.

This paper presents an integrated multiproxy approach study (sedimentological, geochemical, preliminary smear-slides diatom assemblages, and 14C ages analyses) performed on a sediment core collected in Cape Hallett Bay (Ross Sea, Antarctica). Sediments record the early Holocene rapid climate changes: buried varved diatomaceous ooze on the base of core (>9.5–9.4 ka BP) are linked to the early Holocene warming and open marine conditions. From 9.4 ka BP, the climate starts to cool (massive mud). From 8.0 to 7.8 ka BP, sandy mud sediment suggests a rapid landward recession of the local/regional glaciers, with relevant underflow inputs, together with the onset of seasonal sea-ice formation. The ages and the characteristics of the youngest sediments are related to the changed oceanographic conditions linked to the retreat of the calving front of the Ross Ice Shelf.

Karsts areas are “landscapes of special geological and geomorphologic interest which call for conservation” and can therefore be defined as potential geosites according to the definition given by Cleal et al. [2]. This communication briefly describes the geological, geomorphologic and hydrogeologic features of the most important areas in North-Eastern Italy where highly karstified – both on the surface and underground – carbonate rocks outcrop. Some of them perfectly exemplify geological and geomorphologic events and their own geological history, thus serving as cultural models not only at a local but also at a global level [1]. Typical examples of karst geosites are the Alpine Karst environment ofMt Canin and the Classical Karst near Trieste, as well as the Cansiglio – Cavallo Plateau, the limestone turbidites of Julian Prealps Flysch, the glaciokarst valleys of the Carnic Alps and the karren of the Devonian limestone.

Three gravity cores collected during the austral summer 1990–91 in different areas of the Ross Sea continental shelf have been studied. Sedimentological, micropalaeontological and chronological data show evidence for the different evolution of the Drygalski Basin, the Joides Basin and the Cape Adare area, during the late Quaternary. The advance of glaciers during LGM is well documented in the Drygalski Basin, where a basal till testifies the presence of an ice sheet anchored on the seafloor. In contrast, a glacial marine diamicton with calcareous foraminifers in the basal part of the core collected in the Joides Basin indicates that the West Antarctic Ice Sheet was not completely grounded on the seafloor during LGM. The successive deglacial phase is more or less synchronous in both basins (about 17ka B.P.) and is documented in the overlaying units by the occurrence of well-sorted sands and foraminifer colonization. A very different sediment accumulation rate between the Drygalski and the Joides Basins is probably related to higher bioproductivity and mud accumulation in the latter during the Holocene. The Cape Adare area is a different example of environmental evolution, as shown by the presence of biogenic calcareous deposits. These deposits occur throughout the entire core, but they decrease in phase with increasing terrigenous inputs, probably during interglacial times. Within this evolution, foraminiferal and ostracod assemblages are sensitive to glacial/interglacial conditions. Their higher diversity is mainly recorded during glacial time.

The results from some cruises made in order to determine the influence of the Stella river as a source of 137 Cs within the Lignano basin (Marano Lagoon, Northern Adriatic Sea) are presented. The suspended solid transport of this spring river is previously estimated. Furthermore, particle size and composition features of the Stella river particulate suspended matter are used to discuss the 137 Cs in situ K d measured in suspended matter. The pattern of salinity of water bodies in the lagoon, nearby the Stella mouth, confirm the distribution of radiocaesium in the bottom sediments.