Deposits of pyroclastic mass flows at Bibby Hill (Pliocene, James Ross Island, Antarctica)

Sedimentological study of the southern slopes of Bibby Hill (relic of a Pliocene tuff cone) allows recognition of twelve lithofacies and three facies associations. Deposits of pyroclastic currents (both low- and high density pyroclastic currents) dominate over the deposits of pyroclastic flows. Products of suabaerial resedimented pyroclastic deposits play minor role. Vertical distribution of facies associations within the studied succession is not uniform. These differences in the distribution of facies associations are interpreted as response to variations in the intensity and type (Surtseyan, Taalian) of phreato-magmatic eruptions, water availability and morphology of the cone

Bedload geochemical and petrophysical signature of the Algal and Bohemian streams, James Ross Island, Antarctic Peninsula

This study presents the first geochemical and petrophysical data on the composition of the bedload sediments transported by the Algal and Bohemian Stream, and the latter’s prominent tributary: the Dirty Stream. The catchments of these rivers are partially glacierised, with only 2% and 6% ice cover in the Algal and Bohemian stream catchments, respectively. Therefore, the primary sources of liquid water to these rivers are snowmelt and active layer thawing. This study shows that the Cretaceous marine sedimentary rocks deposited in the back-arc James Ross Basin, which underlies the studied rivers, represent the main constituent of fluvial bedload. This is in contrast to suspended sediment loads, whose composition is a mixture of volcanic rocks from the surrounding James Ross Island Volcanic Group. This also suggests that bedload is only transported for a distance of few hundreds of metres, while suspended sediment load is transported throughout the Algal and Bohemian streams to the sea. It is anticipated that this work will serve as the source of data for further studies from fluvial geomorphology to river ecology

Sedimentary petrological characteristics of lateral and frontal moraine and proglacial glaciofluvial sediments of Bertilbreen, Central Svalbard

Bertilbreen is a valley glacier located in the central part of the Spitsbergen Island, Svalbard. Glacier bedrock is composed of Devonian Old Red facies sedimentary rocks, Carboniferous clastic sedimentary rocks and Carboniferous to Permian limestones. Cobble clasts from the right-hand lateral moraine, frontal moraine and proglacial glaciofluvial sediments were studied. The upper part of the lateral moraine is composed mostly of passively transported supraglacial debris (originally unmodified scree, snow and scree/rock avalanche deposits) with a small proportion of actively transported clasts or reworked glaciofluvial sediments. Clasts in the middle part of the lateral moraine originate predominantly from the frontal moraine of a small glacier in the lateral valley. The lower part of the lateral moraine and frontal moraine of Bertilbreen are rich in subglacially transported material, which is supported by isometric clast shapes, roundness degree and common clast surface striations. Coarse gravel forms longitudinal bars in the glaciofluvial stream flowing from the glacier front. In the southern mouth of the valley, the proglacial stream grades into a braided outwash fan. Clast nature is affected by the source from the surrounding glacial deposits and bedrock outcrops, the impact of glaciofluvial transport on the clast nature increases in the braided outwash fan. Clast shapes are primarily influenced by bedding and fractures of source rocks, but are also significantly influenced by the type and proximity of material sources. Striation is cleared away the clast surface during the glaciofluvial transport. A morphostrati-graphically older glaciofluvial terrace formed by glaciofluvial sediments deposited during the glacier advance culminating during the Little Ice Age (LIA) is located at the southern end of the valley. The comparison of active proglacial stream sediments and those from older glaciofluvial terrace was done using the coarse pebble fraction

Foraminifera from the Upper Cretaceous of northern James Ross Island (Antarctica): a preliminary report

The Cretaceous biostratigraphy of the James Ross Island region is generally based on palynomorphs and macrofossils (bivalves, ammonites). During geological mapping of the northern James Ross Island a number of samples from Upper Cretaceous lithologies were gathered to test the presence of foraminifers as a possible tool for stratigraphic evaluation of Upper Cretaceous strata. Limited number of samples did not provide foraminiferal content large enough to give relevant information for biostratigraphic conclusions. Samples from older sediments of Whisky Bay and Kotick Point formations (Albian – Turonian) were either not fossiliferous or contained scarce specimens of agglutinated foraminifers. Foraminiferal assemblages from younger sediments of Hidden Lake and Santa Marta formations (Coniacian – Campanian) contained species with both agglutinated and calcareous types of tests. Many of studied marine sediments were barren of foraminifers, probably due to late diagenetic secondary decalcification. Taxonomy of low-diversified assemblages was carried out and a biostratigraphical and palaeobiogeographical significance discussed

Stabilisation of geodetic points in the surroundings of Johann Gregor Mendel Station, James Ross Island, Antarctica

The article is focused on issuing of the permanent stabilisation of geodetic points in the periglacial environment. Periglacial environment of ice-free areas of northern James Ross Island is characterised by specific geomorphological processes connected with freezing and thawing and mass movement processes in the superficial part of the ground. Variable intensity of periglacial processes creates main limitations for traditional methods of permanent geodetic point’s stabilisation. This article describes periglacial processes with regards to the traditional stabilisation methods and suggests alternative solutions, which were practically applied and verified on the ice-free area of Ulu Peninsula, northern James Ross Island

Biodiversity of freshwater algae and cyanobacteria on deglaciated northern part of James Ross Island, Antarctica. A preliminary study.

Freshwater algae and cyanobacteria have been studied at the James Ross Island (Ant- arctica) since the first Czech expedition to the James Ross Island area in austral summer of 2004. Main emphasis, however, has been devoted to cyanobacteria and diatoms. Therefore, recent knowledge on biodiversity of freshwater species of green algae is fragmentary. The main aim of presented study was to contribute to species list of green algae and cyanobacteria from James Ross Island. To evaluate species richness of algae and cyanobacteria, samples of water/mats from 6 different lakes, shallow ponds, and seepages located in northern deglaciated part of the James Ross Island were collected in austral summers 2012 and 2013, respectively. The samples were analysed using optical microscopy approach after transport to Czech laboratories. Algal and cyanobacterial taxa were determined according to morphological characteristics. Frequencies of individual taxa occurrence in samples were evaluated. Species richness differences between sampling sites was found. Dominating taxa differed between collection sites as well. Altogether, 41 algal and cyanobacterial taxa were found. Some species and genera: Cosmarium sp., Actinotaenium curtum, Staurastrum punctulatum and Chlorobotrys regularis are reported for James Ross Island for the first time. In some samples, there were some species that remained undetermined due to limitations of light microscopy and morphological approach.Byly studovány sladkovodní řasy a sinice ostrova Jamese Rosse, Antarktida. Výsledky analýzy biodiverzity jsou uvedeny podle charakteru stanoviště.Freshwater algae and cyanobacteria have been studied at the James Ross Island (Ant- arctica) since the first Czech expedition to the James Ross Island area in austral summer of 2004. Main emphasis, however, has been devoted to cyanobacteria and diatoms. Therefore, recent knowledge on biodiversity of freshwater species of green algae is fragmentary. The main aim of presented study was to contribute to species list of green algae and cyanobacteria from James Ross Island. To evaluate species richness of algae and cyanobacteria, samples of water/mats from 6 different lakes, shallow ponds, and seepages located in northern deglaciated part of the James Ross Island were collected in austral summers 2012 and 2013, respectively. The samples were analysed using optical microscopy approach after transport to Czech laboratories. Algal and cyanobacterial taxa were determined according to morphological characteristics. Frequencies of individual taxa occurrence in samples were evaluated. Species richness differences between sampling sites was found. Dominating taxa differed between collection sites as well. Altogether, 41 algal and cyanobacterial taxa were found. Some species and genera: Cosmarium sp., Actinotaenium curtum, Staurastrum punctulatum and Chlorobotrys regularis are reported for James Ross Island for the first time. In some samples, there were some species that remained undetermined due to limitations of light microscopy and morphological approach

Surface mass balance of Davies Dome and Whisky Glacier on James Ross Island, north-eastern Antarctic Peninsula, based on different volume-mass conversion approaches

This study presents surface mass balance of two small glaciers on James Ross Island calculated using constant and zonally-variable conversion factors. The density of 500 and 900 kg·m–3 adopted for snow in the accumulation area and ice in the ablation area, respectively, provides lower mass balance values that better fit to the glaciological records from glaciers on Vega Island and South Shetland Islands. The difference between the cumulative surface mass balance values based on constant (1.23 ± 0.44 m w.e.) and zonally-variable density (0.57 ± 0.67 m w.e.) is higher for Whisky Glacier where a total mass gain was observed over the period 2009–2015. The cumulative surface mass balance values are 0.46 ± 0.36 and 0.11 ± 0.37 m w.e. for Davies Dome, which experienced lower mass gain over the same period. The conversion approach does not affect much the spatial distribution of surface mass balance on glaciers, equilibrium line altitude and accumulation-area ratio. The pattern of the surface mass balance is almost identical in the ablation zone and very similar in the accumulation zone, where the constant conversion factor yields higher surface mass balance values. The equilibrium line altitude and accumulation-area ratio determined for the investigated glaciers differ by less than 2m and 0.01, respectively. The annual changes of equilibrium line altitude and the mean values determined over the period 2009–2015 for Whisky Glacier (311 ± 16 m a.s.l.) and Davies Dome (393 ± 18 m a.s.l.) coincide with the values reported from Bahía del Diablo Glacier on Vega Island but differ from the glaciological records on South Shetland Islands

Biodiversity of freshwater algae and cyanobacteria on deglaciated northern part of James Ross Island, Antarctica. A preliminary study.

Freshwater algae and cyanobacteria have been studied at the James Ross Island (Ant-arctica) since the first Czech expedition to the James Ross Island area in austral summer of 2004. Main emphasis, however, has been devoted to cyanobacteria and diatoms. Therefore, recent knowledge on biodiversity of freshwater species of green algae is fragmentary. The main aim of presented study was to contribute to species list of green algae and cyanobacteria from James Ross Island. To evaluate species richness of algae and cyanobacteria, samples of water/mats from 6 different lakes, shallow ponds, and seepages located in northern deglaciated part of the James Ross Island were collected in austral summers 2012 and 2013, respectively. The samples were analysed using optical microscopy approach after transport to Czech laboratories. Algal and cyanobacterial taxa were determined according to morphological characteristics. Frequencies of individual taxa occurrence in samples were evaluated. Species richness differences between sampling sites was found. Dominating taxa differed between collection sites as well. Altogether, 41 algal and cyanobacterial taxa were found. Some species and genera: Cosmarium sp., Actinotaenium curtum, Staurastrum punctulatum and Chlorobotrys regularis are reported for James Ross Island for the first time. In some samples, there were some species that remained undetermined due to limitations of light microscopy and morphological approach. We plan to sample those locations of the James Ross Island that have never been investigated before for future studie