The aim of this paper is to characterise the internal structures and ice-flow history of representative valley glaciers in Svalbard and infer from them dynamic changes over centennial timescales. Three polythermal and one cold valley glacier are investigated using field- and laboratory-based techniques and remote sensing. Structures along flow-unit boundaries indicate that ice-flow configuration in three of the glaciers has remained stable spanning the residence time of the ice. Deformation of a flow-unit boundary in the fourth reveals an ice-flow instability, albeit one that has been maintained since its most recent advance. Macro-crystallographic, sedimentological and isotopic analyses indicate that basal ice is elevated to the glacier surface, as shown by entrained sediments and enrichment in heavy isotopes. In narrow zones of enhanced cumulative strain, new ice facies are generated through dynamic recrystallisation. The surface density of longitudinal foliation is shown to represent the relative magnitude of cumulative strain. Geometric similarities between flow-unit boundaries in Svalbard valley glaciers and larger scale longitudinal surface structures in ice sheets suggest that deformation mechanisms are common to both.

A calcium-silicate xenolith (no. 11) from the ignimbrite of the Upper Chegem Caldera in Kabardino-Balkaria, Russia, has revealed a diverse mineral assemblage with As- and B-bearing phases from the apatite supergroup such as the svabite and johnbaumite–hydroxylellestadite series, in addition to cahnite and datolite. Three distinct zones of variable arsenic content have been investigated. Notably, the outermost altered zone adjacent to the ignimbrite hosts the highest concentration of arsenic and arsenate minerals. A detailed structural analysis using Raman spectroscopy was carried out to investigate the distribution of boron and arsenic in tetrahedral coordination. This has provided the basis for describing a solid-solution system between hydroxylellestadite, svabite and johnbaumite and can be used as a novel technique for identifying apatite-supergroup minerals. One aim of the analysis was to elucidate the origin of various elements and content levels, particularly in relation to the distance from the xenolith–ignimbrite contact. The presence of boron and arsenic, probably derived from ignimbrites, highlights the important role of volcanic rocks as potential contributors of these elements in mineral formation processes.

This work presents the results of an investigation of an assemblage of secondary Sc-minerals from the intraplutonic metaluminous pegmatite Kožichovice II, Třebíč Pluton, Czech Republic. The assemblage was formed by hydrothermally-induced dissolution of primary Sc-enriched (≈1.6 wt.% Sc2O3) columbite-(Mn) followed by in situ reprecipitation of volumetrically dominant fersmite (≈0.16 wt.% Sc2O3) and minor nioboheftetjernite (ScNbO4). Subsequent hydrothermal processes resulted in the formation of fluorcalciomicrolite + Sc-minerals (thortveitite + kristiansenite) + titanite. The mass balance calculations (based on EPMA-derived mineral compositions, mineral proportions obtained from TIMA automated mineralogy and textural observations) revealed that the amount of Sc released from the replaced mass of columbite-(Mn) is significantly higher than the amount of Sc incorporated in the mass of the secondary minerals. This indicates that part of the Sc was mobilised and released to the host rocks (pegmatite and granite). The secondary mineral assemblages indicate elevated Ca activity in the alteration fluids. Other occurrences of Sc-minerals in pegmatites (Baveno Pluton and Heftetjern pegmatite) show remarkable similarities in the paragenetic position of Sc-minerals (late hydrothermal/replacement minerals), including the high activity of Ca in fluids during their formation. The high activity of Ca in fluids during the metasomatic replacement of Sc-enriched precursors causes the formation of the volumetrically dominant Sc incompatible phases, followed by a local supersaturation of Sc resulting in the crystallisation of secondary Sc-minerals.

As a natural clay mineral, halloysite (Hal) possesses a distinctive nanotubular morphology and surface reactivity. Hal calcined at 750°C (Hal750°C; 0.0, 1.0, 2.0, 4.0, 6.0, 8.0 wt.%) was used to replace ground granulated blast furnace slag (GGBFS; 50.0, 49.5, 49.0, 48.0, 47.0, 46.0 wt.%) and fly ash (FA; 50.0, 49.5, 49.0, 48.0, 47.0, 46.0 wt.%) for the preparation of geopolymer in this study. The effects of the replacement ratio of Hal750°C on setting time, compressive strength, flexural strength, chemical composition and microstructure of the geopolymer were investigated. The results indicated that Hal750°C did not significantly alter the setting time. The active SiO2 and Al2O3 generated from Hal750°C participated in the geopolymerization, forming additional geopolymer gel phases (calcium (aluminate) silica hydrate and sodium aluminosilicate hydrate), improving the 28 day compressive strength of the geopolymers. When the amount of Hal750°C was 2.0 wt.%, the 28 day compressive strength of the ternary (GGBFS-FA-Hal750°C-based) geopolymer was 72.9 MPa, 34.8% higher than that of the geopolymer without the addition of Hal750°C. The special nanotubular morphology of residual Hal750°C mainly acted like reinforcing fibres, supplementing the flexural strength of the geopolymer. However, excessive Hal750°C addition (>4.0 wt.%) reduced compressive and flexural strength values due to the low degrees of geopolymerization and the porous microstructure in the ternary geopolymer. These findings demonstrate that the appropriate addition of Hal750°C improved the compressive strength of geopolymers prepared using GGBFS/FA, which provides essential data for future research and supports the utilization of low-value Hal-containing clays in geopolymer preparation.

Parisite-(Nd) (IMA2024-013), ideally CaNd2(CO3)3F2, as the Nd-dominant analogue of parisite-(Ce), occurs in dolomitic marble in the Bayan Obo Fe–Nb–REE deposit, Inner Mongolia, China. It is associated with calcite, aegirine, magnetite, hematite, fluorite, riebeckite, bastnäsite-(Ce), baryte, aeschynite-(Ce), aeschynite-(Nd), monazite and parisite-(Ce). Parisite-(Nd) occurs as subhedral to anhedral irregular grains from 0.02 mm to 1 mm. Parisite-(Nd) is transparent, yellowish-brown colour, with pale yellow streak and displays vitreous to resinous lustre. Cleavage is distinct on pseudo-{001}; fracture is uneven, or conchoidal. The Mohs hardness is 4 to 5, and it is brittle. The calculated density of parisite-(Nd) is 4.357 g/cm3. Parisite-(Nd) is pseudo-uniaxial (+), ω = (1.679) and ε = (1.754). The empirical formula is (Ca0.945Fe0.058Sr0.015Ba0.007)Σ1.025(Nd0.967Ce0.529La0.191Pr0.137Gd0.070Sm0.029Th0.022Y0.016Nb0.011Ho0.003)Σ1.975(CO3)3F1.893OH0.023. The Raman spectra of parisite-(Nd) show strong and sharp peaks at 1113, 1090, 825, 635 and 1608 cm–1 and moderate to weak bands centred at 255, 392, 739, 924, 1183, 1228, 1296, 1640, 2247, 2924 and 3065 cm–1. Powder X-ray diffraction and TEM studies give the following results: monoclinic, space group: Cc (# 9), a = 12.3283(13) Å, b = 7.1185(4) Å, c = 28.4633(37) Å, β = 98.529(14)°, V = 2470.28(42) Å3 and Z = 12.

The relevance of education and outreach (E&O) activities about the Antarctic Treaty has been recognized at the Antarctic Treaty Consultative Meetings (ATCM) and at the Committee for Environmental Protection (CEP). This study examines the key topics and the target audiences detailed in papers submitted to the ATCM on E&O. Since the Antarctic Treaty entered into force in 1961, a total of 216 ATCM papers on E&O have been produced. The number of papers has increased substantially since the mid-1990s. ‘Science’ (76.9%) and ‘Wildlife/Biodiversity/Environment’ (75.5%) were the most addressed topics in these papers, while the ‘Public’ (81.0%) and those attending ‘Schools’ (69.0%) are the main target audiences. ‘Science’ in ATCM papers increased ~120-fold from 1961–1997 to 2015–2023, while ATCM papers discussing engagement with the ‘Public’ increased ~40-fold during the same period. ‘Climate change’ was first mentioned in 2006, and the number of papers per year increased fourfold by 2015–2023. This study shows the increasing interest in E&O through time, addressing key topics to relevant audiences related to the Antarctic region. From an educational perspective, attention should be paid to emerging topics (e.g. equity, diversity and inclusion), and the engagement of early-career professionals and educators should be made a priority.

Modern fluvial sediments provide important information about source-to-sink process and regional tectono-magmatic events in the source area, but many factors, e.g., chemical weathering, sedimentary cycles and source-rock types, can interfere with the establishment of the source-sink system. The Lalin River (LR) and the Jilin Songhua River (JSR) are two important tributaries of the Songhua River in the Songnen Plain in NE China. They have similar flow direction, topography and identical climate backgrounds, but have notably different parent-rock types in the headwater, which provides an opportunity to explore the influencing factors of river sediment composition. To this end, the point bar sediments in the two rivers were sampled for an analysis of geochemistry (including element and Sr-Nd isotopic ratios), heavy mineral and detrital zircon U-Pb dating. The results are indicative of the fact that the two rivers have the similar geochemical composition (e.g., elements and Sr isotopes) as well as chemical weathering (CIA = 51.41–57.60, CIW = 59.68–66.11, PIA = 51.95–60.23, WIP = 56.00–65.47, Rb/Sr = 0.38–0.42) and recycling (SiO2/Al2O3 = 5.79 and 5.03, ICV = 1.0 and 1.2, CIA/WIP = 0.81–1.03) characteristics, showing a major control of climate on the low-level weathering and recycling of the river sediments. However, there are significant differences in the detrital zircon U-Pb age (a significant Mesozoic age peak for the LR but an additional Precambrian peak for the JSR), Nd isotope ratio (−6.2812–8.5830 and −8.1149–10.2411 for the LR and the JSR, respectively) and to a certain extent heavy mineral composition (e.g., for the < 63 μm fraction, a dominance of hornblende and magnetite in the LR, but haematite-limonite in the JSR) in the two river sediments, indicating that source rocks largely control the composition of the river sediments. Some of the major tectono-magmatic events (e.g., crustal growth and cratonisation of the North China Craton, closure of the Paleo-Asian Ocean, subduction and rollback of the Paleo-Pacific plate) occurring in the eastern Songnen Plain are well documented in the JSR sediments but not in the LR, the difference of which is largely regulated by the source rocks in the source area.

Different two-dimensional structural units of layered silicate minerals have different chemical and reaction properties. Sulfuric acid solution mineral-leaching systems with pH of 2.0, 4.0 and 6.0 were constructed to investigate the differential dissolution properties of lizardite (1:1 type), chlorite and talc (2:1 type minerals) and the chemical kinetic mechanism of the mineral–water interface reaction. The results showed that the dissolution efficiency of Mg in lizardite is higher than that of chlorite and talc in acidic environments (pH of 2.0, 4.0 and 6.0). The dissolution efficiency of Mg in chlorite is greater than that of talc for acidic environments when pH is 2.0 and 4.0, but chlorite and talc have nearly identical Mg dissolution efficiencies at a pH of 6.0. This phenomenon is related to the defect site on the tetrahedral sheet of chlorite and is controlled by the change of the dissolution efficiency of Al. The dissolution rates of Mg and Si in lizardite, chlorite and talc decreased with the increase of reaction time in the acidic medium for pH = 2.0, 4.0 and 6.0, and there are two linear dissolution trends at different pH values. The dissolution efficiencies of Mg and Si in lizardite, chlorite and talc were simulated and predicted by establishing a logistic model. It was found that the maximum dissolution efficiency of 2:1 type minerals chlorite and talc are only 4.72% and 1.58%, which is much lower than that of 1:1 type lizardite. This research on the reaction mechanism and dissolution kinetics of lizardite, chlorite and talc not only helps to deepen the understanding of the mineral–water interface interaction, but also reveals the different rules for Mg, Si and Al dissolution in different types of trioctahedral mineral–water interface reactions, and provides a crystal chemical basis for the ion migration and action mechanism of minerals.

The study area Sonapahar is an integral part of Shillong Meghalaya Gneissic Complex (SMGC), which is located in the Northeastern part of India. This complex mainly comprises metamorphic formations spanning from Upper Amphibolite to Ultra-high temperature granulite, interspersed with various igneous intrusions. In this study, particular attention is directed towards unravelling the metamorphic history of Mg-Al granulite. For the very first time, we establish the pressure–temperature (P-T) trajectory of the Mg-Al granulite from Sonapahar, SMGC. Employing conventional thermobarometry along with winTWQ analysis, the inferred metamorphic conditions for this granulite reveal temperatures exceeding 900°C and pressures of approximately >8 kbar. These conditions firmly indicate the presence of ultra-high-temperature metamorphism. By utilizing the Perple_X software in the MnO-Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2-Fe2O3 compositional system, we construct a P-T pseudosection. This gives a clockwise P-T path, signifying an episode of cooling (+ minor decompression). Such a pattern also suggests rapid cooling of the tectonically-thickened crust. Concurrently, a geochemical exploration of trace and rare earth elements in the rocks offers further insights. These investigations give an idea about the protolith, having a clay-to-sandstone in nature. Additionally, chemical data from monazite within the studied rock provide a weighted mean age of 682 Ma for the peak metamorphic stage. This age aligns with the global Pan-African orogenic events. The biotite K-Ar isotopic geochronology from the symplectite position provides decompression history or cooling age of 442 Ma. This age corresponds to a period after the last peak metamorphic phase that occurred during the Pan-African thermal event.

Peatlands, covering approximately one-third of global wetlands, provide various ecological functions but are highly vulnerable to climate change, with their changes in space and time requiring monitoring. The sub-Antarctic Prince Edward Islands (PEIs) are a key conservation area for South Africa, as well as for the preservation of terrestrial ecosystems in the region. Peatlands (mires) found here are threatened by climate change, yet their distribution factors are poorly understood. This study attempted to predict mire distribution on the PEIs using species distribution models (SDMs) employing multiple regression-based and machine-learning models. The random forest model performed best. Key influencing factors were the Normalized Difference Water Index and slope, with low annual mean temperature, with low annual mean temperature, precipitation seasonality and distance from the coast being less influential. Despite moderate predictive ability, the model could only identify general areas of mires, not specific ones. Therefore, this study showed limited support for the use of SDMs in predicting mire distributions on the sub-Antarctic PEIs. It is recommended to refine the criteria used to select environmental factors and enhance the geospatial resolution of the data to improve the predictive accuracy of the models.