The geochemistry of lake sediments provides valuable information on environmental conditions and geochemical processes in polar regions. To characterize geochemical composition and to analyse weathering and provenance, 26 lakes located in six islands of the South Shetland Islands (SSI) and James Ross Archipelago (JRA) were analysed. Regarding major composition, the studied lake sediments correspond to ferruginous mudstones and to a lesser extent to mudstones. The weathering indices indicate incipient chemical alteration (Chemical Index of Alteration = 52.6; Plagioclase Index of Alteration = 57.6). The La-Th-Sc plot shows different provenance signatures. SSI lake sediments correspond to oceanic island arcs, whereas those of JRA denote a signal of continental arcs with mixed sources. In James Ross Island lake sediments are of continental arcs (inland lakes), oceanic island arcs (coastal lakes) and a middle signature (foreland lakes). Multi-elemental analysis indicates that the sediments are enriched from regional basalts in Ba, Rb, Th, Cs and U (typical of silica-rich rocks) and depleted in Cr and Co due to mafic mineral weathering. The geochemical signals identified by principal component analysis enable us to group the sediments according to the studied islands and their geomorphological characteristics. This study underlines the importance of knowing the geochemical background levels in pristine lake sediments to evaluate potential future anthropogenic effects.

As part of a project aiming to determine the lichenised fungal biodiversity of James Ross Island (Eastern coast of Antarctic Peninsula), we identified three infrageneric taxa which were previously not reported from Antarctica: Farnoldia micropsis (A. Massal.) Hertel, Gyalolechia epiphyta (Lynge) Vondrák and Placidium squamulosum var. argentinum (Räsänen) Breuss. Detailed morphological and anatomical properties of these species along with photographs based on the Antarctic specimens are provided here. In addition, the nrITS, mtSSU and/or RPB1 gene regions of the selected specimens are studied and the phylogenetic positions of the species are discussed. The DNA sequence data for Farnoldia micropsis are provided for the first time. Farnoldia micropsis and Gyalolechia epiphyta are also new to the Southern Hemisphere.

The Northern Prince Gustav Ice Stream located in Prince Gustav Channel, drained the northeastern portion of the Antarctic Peninsula Ice Sheet during the last glacial maximum. Here we present a chronology of its retreat based on in situ produced cosmogenic 10Be from erratic boulders at Cape Lachman, northern James Ross Island. Schmidt hammer testing was adopted to assess the weathering state of erratic boulders in order to better interpret excess cosmogenic 10Be from cumulative periods of pre-exposure or earlier release from the glacier. The weighted mean exposure age of five boulders based on Schmidt hammer data is 12.9 ± 1.2 ka representing the beginning of the deglaciation of lower-lying areas (< 60 m a.s.l.) of the northern James Ross Island, when Northern Prince Gustav Ice Stream split from the remaining James Ross Island ice cover. This age represents the minimum age of the transition from grounded ice stream to floating ice shelf in the middle continental shelf areas of the northern Prince Gustav Channel. The remaining ice cover located at higher elevations of northern James Ross Island retreated during the early Holocene due to gradual decay of terrestrial ice and increase of equilibrium line altitude. Schmidt hammer R-values are inversely correlated with 10Be exposure ages and could be used as a proxy for exposure history of individual granite boulders in this region and favour the hypothesis of earlier release of boulders with excessive 10Be concentrations from glacier directly at this site. These data provide evidences for an earlier deglaciation of northern James Ross Island when compared with other recently presented cosmogenic nuclide based deglaciation chronologies, but this timing coincides with rapid increase of atmospheric temperature in this marginal part of Antarctica.

The origin and nature of seal carcasses scattered around the Ulu Peninsula, James Ross Island, is examined using robust and novel multidisciplinary analysis. Spatial distribution analysis indicates their predominance at low elevations and on surfaces with negligible slope. The seals died throughout the last century. Dental cement increments indicate that the seals died in late winter, and we interpret this to show an influence of the persistence and break-up of sea ice and the appearance of pools/cracks in the northern Prince Gustav Channel on death. Specifically, after being trapped by a late winter freeze-up the seals search for open water, become disoriented by snow-covered flat valleys and move inland. Carcasses from all age groups of crabeater seal are found on land, but inland movement is less notable for Weddell and leopard seals. Although most carcasses appear to have remained unchanged during the last 10 years due to the cold and dry conditions, a few carcasses that are located in sites of snow accumulation and subsequent melting have undergone enhanced decay. Decaying seal carcasses represent loci of nutrient release in a nutrient deficient environment and are colonized by algae, cyanobacteria, lichens and mosses. This research suggests further useful studies for the future.

A new species of Antarctoxylon is described from the Coniacian Hidden Lake Formation of James Ross Island as A. mixai Sakala, sp. nov. This angiosperm fossil wood shows a unique combination of features in having indistinct growth ring boundaries, scalariform perforation plates with about 30 bars and rays both narrow (1–6-seriate) and very wide (up to 18-seriate). Its systematic affinities and exact living relative at the specific, generic or even familial level cannot be specified. Along with Weinmannioxylon nordenskjoeldii from James Ross Island and the angiosperm woods from the Williams Point on Livingston Island, this record provides further evidence of the earliest record of arboreal angiosperms in Antarctica.

The oldest record of the hexanchiform sharks from the Southern Hemisphere and the second chondrichthyan report known from Carboniferous to Early Cretaceous beds in Antarctica is given. The material was collected in late Aptian rocks of the Kotick Point Formation outcropping in the western part of James Ross Island, near Antarctic Peninsula. It consists of an isolated tooth assignable to a hexanchiform different from the other described genera. The tooth shows putative plesiomorphic cusp (few cusps, no serrations) and apomorphic root characters (relatively deep, quadrangular). It could be related to a species close to the origin of Hexanchus (unknown in beds older than Cenomanian).

Zircon and apatite fission track (AFT) thermochronology was applied to the James Ross Basin sedimentary rocks from James Ross and Seymour islands. The probable sources of these sediments were generated in Carboniferous to Early Paleogene times (∼315 to 60 Ma). The total depths of individual James Ross Basin formations are discussed. The AFT data were modelled, and the thermal history model was reconstructed for samples from Seymour Island. The first stage after a period of total thermal annealing (when the samples were above 120°C) involved Late Triassic cooling (∼230 to 200 Ma) and is followed by a period of steady cooling through the whole apatite partial annealing zone (PAZ, 60–120°C) to minimum temperature in Paleocene/Early Eocene. The next stage was the maximum burial of sedimentary rocks in the Eocene (∼35 Ma, 1.1–1.8 km) and the final cooling and uplift of Seymour Island sedimentary rocks at ∼35 to 20 Ma.

A new fossil genus of decapod Crustacea, belonging to the family Polychelidae is described from James Ross Island, Antarctic Peninsula. The specimen was obtained from a block of reworked Jurassic tuffaceous black shale belonging to the Ameghino (= Nordenskjöld) Formation in the Lower Cretaceous Kotick Point Formation. This is the first report of fossil Polychelidae in the Southern Hemisphere.

A sedimentary sequence, c. 5–6 km thick, extending from the Kimmeridgian–Upper Eocene crops out in the James Ross Island area, northern Antarctic Peninsula. This succession is the most important onshore Late Cretaceous–Tertiary sequence in Antarctica and is probably one of the most significant Cretaceous sequences in the Southern Hemisphere. However, the understanding of the geological and palaeontological evolution of the area has been limited by an incomplete knowledge of the biostratigraphy of this region. Palynological studies are providing a finer resolution biostratigraphical zonation scheme than previously possible. This paper reviews the stratigraphy of the basin fill succession and provides a framework for the papers published in this Special Issue.

The Lagrelius Point Formation (?Barremian–Aptian) is the basal unit of the Gustav Group and crops out on the north-west coast of James Ross Island. It consists of about 250 m of coarse-grained siliciclastic rocks. The type section of the Lagrelius Point Formation is defined here from just south of Lagrelius Point. The measured section comprises the uppermost 80 m of the unit and mainly consists of clast-supported, boulder, cobble to pebble conglomerates; very coarse to medium-grained sandstones occur rarely. Four sedimentary facies are recognized. A disorganized conglomerate facies (1) is interpreted as having been deposited from non-cohesive debris flows and high density gravelly turbidity currents. Inversely graded conglomerate facies (2) and normally graded to graded stratified conglomerate and pebbly sandstone facies (3) reflect sedimentation from high density gravelly turbidity currents. Massive and parallel stratified sandstone facies (4) is thought to record deposition from high density sandy turbidity currents. Two types of facies assemblages have been recognized. A major channel assemblage, represented by the lower part of the measured section and the minor channel assemblage forming the upper part of the section. The total succession is thought to represent the aggradation of a major submarine braided channel followed by the establishment and subsequent infill of a series of minor channels in a marginal terrace.