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In high-level nuclear waste (HLW) repositories, concrete and compacted bentonite are designed to be employed as buffer materials, which may raise a problem of interactions between concrete and bentonite. These interactions would lead to mineralogy transformation and buffer performance decay of bentonite under the near field environment conditions in a repository. A small-scale experimental setup was established to simulate the concrete-bentonite-site water interaction system from a potential nuclear waste repository in China. Three types of mortars were prepared to correspond to the concrete at different degradation states. The results permit the determination of the following: (1) The macro-properties of Gaomiaozi (GMZ) bentonite (e.g. swelling pressure, permeability, the final dry density, and water content of reacted samples); (2) The composition evolution of fluids from the synthetic site water-concrete-bentonite interaction systems; (3) The sample characterization including Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Under the infiltration of the synthesis Beishan site water (BSW), the swelling pressure of bentonite decreases slowly with time after reaching its second swelling peak. The flux decreases with time during the infiltrations, and it tends to be stable after more than 120 d. Due to the cation exchange reactions in the BSW-concrete-bentonite systems, the divalent cations (Ca and Mg) were consumed, and the monovalent cations (Na and K) were released. The dissolution of minerals in the bentonite such as albite causes Si increasing in the pore water. It was concluded that the hydro-mechanical property degradation of bentonite takes place when it comes into contact with concrete mortar, even under low-pH groundwater conditions. The soil dispersion, the uneven water content, and the uneven dry density in bentonite samples may partly contribute to the swelling decay of bentonite. Therefore, the direct contact with concrete has an obvious effect on the performance of bentonite.

The Mélange in Lamphun Province, situated in the southern region of the Chiang Mai-Chiang Rai Suture Zone (CMCRSZ), remains inadequately explored. This study employs field investigations and petrographic analysis to delineate the characteristics of the CMCRSZ Mélange, identifying nine distinct rock units. These units include Carboniferous quartz arenite interbedded with fine-grained sedimentary rocks, Permian lithic graywacke, Permian limestone hosting Pseudodaliolina sp. and Schwagerinid sp., Triassic chert containing Anisian radiolarian fossils, and ocean island basalt. This area exhibits complex folding and thrusting, accompanied by granitic intrusions and low-grade metamorphic rocks within a finer-grained sedimentary matrix. Stratigraphic assessments trace the primary material of the accretionary complex to the upper strata of the oceanic plate stratigraphy. Geochemical analyses indicate the mafic rocks as alkaline to subalkaline basalts, indicative of formation through an alkaline magma series, a conclusion supported by rare-earth element patterns. Sr/Nd isotope classification suggests ocean island tectonics for these rocks. The formation of the CMCRSZ Mélange occurred during the Paleo-Tethys oceanic crust subduction beneath the Indochina Terrane at the Permian-Triassic Boundary, accumulating diverse materials in a dynamically evolving tectonic context. Furthermore, S-type Triassic granites emerged post-collision during the Indosinian Orogeny following the thrusting of the CMCRSZ onto Sibumasu.

The Arctic region is covered with numerous small lakes whose ecosystems are vulnerable to current climate warming and resultant changes in water temperature, ice-cover duration and lake levels. Data on thermal features of these lakes are sparse, which hinders our understanding of the possible ecosystem impacts of the warming climate and climate feedbacks at larger spatial scales. We investigated spatial–temporal variations of lake surface water temperatures (LSWT) in 12 Arctic lakes in north-west Finnish Lapland and explored the predominant drivers of LSWTs by continuous year-round observations. The lake surface temperature data were recorded using thermistors at bi-hourly resolution during the years 2000, 2007–08 and 2019–2021. A large regional heterogeneity was observed in the timing of the maximum and minimum LSWTs and the overall patterns of the annual cycle. Our results reveal that July air temperature, maximum lake depth and altitude explained most of the variance in the summer LSWT (> 85%). The remaining variance was related to geographic location (longitude and latitude), lake morphometric features, such as lake area and catchment area, and certain physico-chemical characteristics, such as Secchi depth and dissolved organic carbon content. Our results provide new insights into thermal responses of different types of small Arctic lakes to climate change.

Abstract Diverse applications and tremendous usefulness of siliciclastic sedimentary sands make investigation into their mechanics of behaviour very essential globally. This study examines the convergence or otherwise of the specimens in compression; physical, fabric, chemical and mineralogical characteristics and their relationships with compression behaviour; shape characteristics, possible particle breakage and their overall effect on the behaviour of siliciclastic sedimentary sands obtained from two locations. The findings are as follows; (a) Siliciclastic sedimentary sands are poorly graded and coarse in nature. (b) The fabrics are characterized by aggregation of sub rounded particles and smaller particles tend to combine with fines to form coatings around bigger particles. (c) Chemical compositions are predominantly silica and alumina and heamatite are significant. (d) Quartz dominates the mineralogy and the other minerals are muscovite, albite, orthoclase and chlorite. (e) The samples have convergent behaviour and the compressibility is not significantly different but lower than the related materials. (f) The original particle is sub round in shape and the particles become sub angular after the test with no relationship between particle shape and compression behaviour. (g) The particle breakage is linked to coarser nature of the specimens and the overall effect of particle breakage on the compression behaviour of siliciclastic sedimentary sand is small.

This study aims to contribute to understanding the processes influencing the spatial distributions of trace metal elements in surface sediments of Brenne's ponds (France) and assess potential pollution levels in the area. It was motivated by the lack of knowledge regarding the hydrogeochemical dynamics of limnic entities, which are ponds. To achieve this, 25 sediment samples were collected from Pond Thomas , considered as a ‘sentinel pond’, and underwent analysis for grain size, total organic carbon (TOC) concentrations, and trace metal elements (TMEs) (specifically Cu, Ni, Pb, As, Zn, Cr, and Cd). The results revealed that trace metal elements are primarily concentrated in two areas: the northwest section and the upstream region in the southern part of the pond. Applying various pollution indicators such as the enrichment factor (EF), geo-accumulation index (Igeo), and potential ecological risk index (RI), it was found that Pb and As are the most enriched elements, with respective EFs of 3.5 and 4.9. Their average concentrations exceed geochemical background values by 4 and 5.68 times in certain samples. The sediments in the southern part of the pond showed moderate contamination levels for As and Pb, with moderate to severe pollution (2 < Igeo < 3), reaching a maximum Igeo of 2.26 for As. Although the RI values across the pond are relatively low, Cd and As still pose moderate potential ecological risks. Additionally, principal component analysis and Pearson correlation analysis indicated two sources of TMEs in the area: Zn, As, Ni, Cd, Pb, and Cr are primarily from natural sources, while Cu appears to have a local anthropogenic origin.

Abstract The use of tracers, particularly isotope geochemistry tracers, is the most efficient method for understanding and providing fresh perspectives on hydrologic processes. The purpose of this study is to determine the stable isotope and geochemical characteristics of groundwater alluvial aquifers in eastern Ethiopia. Samples of water from rainfall, surface water, and groundwater sources were gathered and analyzed. The research discovered that EC, pH, and TDS fluctuated from 871 to 6090 μS/cm, 6 to 8.2, and 558 to 3898 mg/L, correspondingly. In both regions major cation and anion concentrations fall in the order of Ca2+ > Na+ > Mg2+ > K+ and SO4 2− > HCO3 − > Cl− > NO3 − respectively. The most common water types are mixed Na-Mg-Ca, Ca-Cl, Na-Cl, and Ca- HCO3 −. Hydrogeochemical experiments revealed that carbonate and silicate weathering and ionic exchanges primarily govern the supply of important ions in the waters and the geochemical history. The stable isotopic compositions vary from − 2.772 to − 0.418 ‰ with a mean value of− 1.772 ‰, for oxygen and from− 10.37 to 1.01 ‰ with a mean value of− 4.306 ‰ for hydrogen. The results show precipitation has been found to have more enriched isotope compositions than groundwater. In other words, both the hydrogen and oxygen isotope of groundwater are depleted than the precipitation isotope composition. The findings contribute to our knowledge of the stable isotope and geochemistry and are useful in determining the primary compositions of groundwater, water type, and the hydrogeochemistry of semi-arid areas.

Chaohu Lake is a representative lake in China that suffers from severe eutrophication and algal blooms. Understanding the changes in the lake’s eutrophic condition over time is essential for its restoration and management under the background of global changes and regional sustainability. In this context, the compositions of carbon and nitrogen isotopes (δ 13Corg and δ 15N, respectively), total organic carbon (TOC), total nitrogen (TN), and carbon–nitrogen ratio (C/N) were analysed to depict the history of eutrophic state of Chaohu Lake, and its relationship with environmental changes. The result show that before the 1950s, the primary productivity of the lake was low. During the period from the 1950s to the 1970s, primary productivity increased substantially due to eutrophication. From the 1970s to the present, as a result of the construction of the Chaohu Floodgate Station, water replacement in the semi-closed Chaohu Lake gradually slowed and nutrients began to accumulate more rapidly. These conditions led to enhanced lake productivity and rapid eutrophication, mainly caused by intensified human activities and increased exogenous inputs. Our findings suggest that the geochemical records (δ 13Corg, δ 15N, TOC, TN, and C/N ratios) in sediment for Chaohu Lake are capable of recording important shifts in the temporal evolution of lake-water trophic state.

This study utilised lithogeochemistry and stable isotope geochemistry to assess the gold mineralisation in the host rocks of the Abansuoso area. It also studied the isotopic signature of hydrothermally altered and unaltered rocks as a tool for the preliminary prospecting of gold in Ghana’s Birimian belt. The research identified a close association between Au and As, Mo, and W, which is characteristic of orogenic gold deposits. The mineralised and unmineralised rocks show similar content of major and trace elements which suggests that the mineralisation did not significantly affect the primary composition of the mineralised rocks. The concentrations of δ18O (8.9‰ to 17.4‰, n = 22, mean = +13.7‰) and δD (−117 to −33‰, n = 22, mean = −57.9‰) in the rocks are comparable to those from other Birimian regions in Ghana and West Africa. The lack of variation in δ18O suggests a system buffered by rocks, with metamorphic fluid originating from rocks with identical δ18O values. However, the effect of mineralisation on the δD values of rocks is substantially more apparent than its effect on the δ18O values of the rocks.

The problems of geoenvironmental consequences of mining operations are especially acute in the arctic and subarctic regions, where the spread of permafrost significantly reduces the buffering capacity of landscapes. The article presents data on the content of heavy metals in the soil cover of the transient zone between the middle taiga and north taiga landscapes of Western Yakutia under the conditions of mining operations and assesses the resistance of different types of soils to heavy metals pollution. Field and laboratory works were carried out in August 2022. The heavy metals content was determined by atomic absorption spectrometry. Specialized software was used for analysis, such as MS Excel 2013, Statistica 12.0, and QGis 3.26.1. Calculation of organic forms of heavy metals in soil solutions was performed using the NICA-Donnan model. In the course of studies, the structure of the soil cover in the Nakyn kimberlite field in the conditions of the mining industrial complex operation was determined and a sketch map of the soil cover of the territory was compiled. The geochemical series of the studied heavy metals is as follows according to the degree of concentration of heavy metals in cryolithic soils: Pb > Zn > Ni > Cu > Cd > As > Hg. Positive correlations between humus and Cd, Pb, Zn, as well as the occurrence of synergism in the Pb–Cd, Zn–Pb, Zn–Cu pairs were revealed. The soils organic matter enhances migration of heavy metals. The man-made input of Ni and Zn in cryolithic soils will lead to increase of mobile fraction. Cd is more mobile in pale-yellow carbonate and cryogenic soils. The regional background level of heavy metals for these types of soils was calculated, which can be used in future works when the intensity of mining operations increases.

Abstract The Troiseck-Floning and Rosskogel nappes are part of the Austroalpine Unit in the eastern part of the Eastern Alps. The nappes are in tectonic contact and comprise Permian to Mesozoic lower greenschist facies metamorphic metasediments, but only the Troiseck-Floning Nappe consists of a pre-Permian crystalline basement (Troiseck Complex) as well. LA-ICP-MS U–Pb zircon ages, Rb–Sr biotite ages and geochemical data unravel the geological evolution of these tectonic units from Neoproterozoic to Mesozoic times. Detrital U–Pb zircon analyses from siliciclastic metasediments of the Troiseck Complex indicate a late Ediacaran to early Cambrian deposition age of the volcanoclastic sequence. The age distribution correlates with a position along the northeastern Gondwana margin. A late Cambrian crystallization age (502.4 ± 6.8 Ma) of granitic intrusions together with evidence for Late Cambrian/Ordovician magmatism and metamorphism indicate a position at an active plate margin. Polyphase overprinting during the Variscan orogeny is recorded by Late Devonian/early Carboniferous pegmatite dikes (~ 353 Ma) that formed after an early Variscan event, while Pennsylvanian ages of overgrowth rims and inherited grains (~ 320 Ma) are evidence for late Variscan metamorphism. Rhyolitic to andesitic volcanic rocks from the Troiseck-Floning and Rosskogel nappes (271–264 Ma) concomitant with intrusions of porphyric granitoids now transformed to augen gneiss (271 Ma) yield evidence for Permian rift-related magmatism that is widely reported from the Eastern Alps and Western Carpathians. Rb–Sr biotite ages (75–74 Ma) indicate Late Cretaceous cooling below c. 300 °C. This relates to Late Cretaceous exhumation of the Troiseck-Floning Nappe following an Eo-Alpine metamorphic overprint at lower greenschist-facies metamorphic conditions. Based on the similar lithostratigraphy, analogous geological evolution and structure, the Troiseck-Floning Nappe represents the lateral extension of the Seckau Nappe. The new dataset also allows for correlations with other basement complexes that occur in the Western Carpathians.

We present a geochemical dataset and cathodoluminescence images of apatite from the Neoarchean (2610 Ma) glimmerite-carbonatite rocks from the Siilinjärvi complex, Eastern Finland. The subhedral, tapered prismatic grains are compositionally fluorapatite, with limited substitution of Ca by Sr, Na and low REE and Si contents. The Sr/Y ratios are among the highest in a global apatite comparison, comparable to those from other calcite carbonatites, dolomite carbonatites, and phoscorites. Some grains show evidence of late- or post-magmatic interaction with a carbonatite magma or a hydrothermal fluid, resulting in REE-rich overgrowth rims or recrystallized grains with abundant fluid inclusions. We interpret the high Sr/Y ratios combined with low REE contents and depleted heavy REE+Y to represent crystallization from a mantlederived carbonatite parental magma. We show that the Siilinjärvi apatite is chemically heterogeneous but with a limited range in compositions. There are noticeable compositional differences on all spatial scales from micrometer to tens of meters, i.e., within a single crystal, between crystals in a sample, between samples and the two individual sampling locations. We conclude that the intra-crystal geochemical variability in apatite is a suitable tracer of the magmatic and post-magmatic evolution of carbonatite complexes.

Four quartz monzonite – granite intrusions forming the Sorsakoski granite lithodeme, are found within the Raahe-Ladoga suture zone in Central Finland. The prevailing potassium feldspar megacrystic quartz monzonites and granites form a bimodal association with diorites and gabbros. The granitoids are mainly calc-alkaline, ferroan, per- to metaluminous, and have high Zr and REE contents. Dominant mafic minerals are biotite and hornblende, clinopyroxene and orthopyroxene are locally present. The mafic units display effects of fractionation of clinopyroxene. In our interpretation, these intrusions were emplaced during regional late stages of deformation and postcrystallisation deformation partitioned into major shear zones leaving bulk of the intrusions relatively undeformed. Based on one new (1876 ± 6 Ma) and one pre-existing (1882 ± 5 Ma) U-Pb zircon age determination, the crystallisation age of the granitoids can be assumed at ca. 1880 Ma. Based on mineralogy, petrography, geochemistry, bimodal nature of magmatism and age, we correlate these intrusions to the A-type rocks of the previously described Saarijärvi suite. This shows that the syn-orogenic A-type magmatism extended eastwards beyond the Central Finland Granitoid Complex.

Consideration is given to results of geochemical analysis of organic matter and oils of the Proterozoic (the RF-V complex) and the Paleozoic (the pay intervals D2, D3, C1-2) of the eastern part of the Volga-Urals petroleum basin. The obtained data is corroborated by results of 2D basin modeling along four regional profiles two of which are situated in the Kama and two in the Belaya parts of the Kama-Belaya aulacogen. An update is given to earlier data on degree of catagenetic alteration of oil/gas source rocks of the Riphean-Vendian play, maps of catagenesis are constructed. New evidence is provided concerning presence of Precambrian oils in the Paleozoic plays. The oils under investigation are mixed – those formed from generation products of the Precambrian (Riphean, Vendian) and Paleozoic (Devonian and Early Carboniferous) source rock intervals. The results of modeling have shown that the principal source rock intervals in the RF-V play of the Kama part of the Kama-Belaya aulacogen are deposits of the Kaltasy formation of the Lower Riphean and the Vereshchagino formation of the Upper Vendian, while in the Belaya part these are rocks of the Kaltasy, Kabakov, Olkhovo, Priyutovo, Shikhan and Leuza formations of the Riphean and the Staropetrovo formation of the Vendian. It is found that the interval of the main oil and gas window increases in the southeastward direction. In both depressions of the Kama-Belaya aulacogen, a single oil play is distinguished that functions within the stratigraphic interval from the Riphean to the Lower Carboniferous. As the principal petroleum source rock intervals within this play, Riphean-Vendian deposits are considered, reservoirs are confined to the Riphean carbonate complex, Upper Vendian and Middle Devonian clastic deposits, while the Upper Devonian – Tournaisian deposits serve as the upper seal.

Abstract The Sukhothai Historical Park, designated as a world heritage site in Thailand, encompasses the remnants of the Sukhothai Kingdom and serves as a valuable locus for geological and geoarchaeological investigations. Situated in the Sukhothai province, the region is characterized by diverse lithologies, including slate, phyllite, and laterite, as well as red bricks (synthetic materials), utilized in the construction of various ancient structures. Petrographic analysis using polarized light microscopy reveals the phyllites as the primary dimension stones, exhibiting foliated and mylonitic textures with small quartz augen. A portable X-ray fluorescence analyzer was employed for geochemical analysis and the analysis of major oxides and trace elements. The resulting data facilitated the classification of protoliths and comparison with rocks from an abandoned quarry near Saritphong Dam in the western part of the historical park. Notably, phyllites utilized in several prominent structures within the park; Wat Saphan Hin, Wat Pa Daeng 2, Wat Thap Sakae, Wat Chetuphon, Wat Sri Chum, and Wat Mangkorn Temples, exhibited similar characteristics to those in the Wat Khao Noi old quarry, as confirmed by Rubidium (Rb) and Strontium (Sr) values. The SiO2/Al2O3 and FeO/K2O ratios were pivotal in identifying the protoliths of the studied phyllites as shales. In summary, the primary dimension stones for Sukhothai Historical Park originated from the western mountain within the park, with laterites sourced from foothill areas. The presence of quartz pebbles in red bricks suggests local sediment utilization, and quartz additions were employed to enhance structural strength. This comprehensive geoarchaeological study sheds light on the geological composition of the Sukhothai Historical Park, providing valuable insights into the selection and utilization of construction materials in this historically significant site.

This study focuses on palaeoenvironmental changes in the Bottomless Lake (Tăul fără fund) Sphagnum peat bog situated near Bǎgǎu in Romania. The central research question was how the lake has changed over time, and how environmental factors and human activities have influenced the changes. By employing previous loss-on-ignition and radiocarbon analyses in addition to new radiocarbon, grain size, magnetic susceptibility and geochemical analyses, a more precise reconstruction of the bog's regeneration and erosion phases was achieved. A multi-proxy analysis of the core sequence provided crucial insights regarding the interconnections between various elements. Notably, plant-derived elements (Na, K) exhibited correlations with organic matter, and carbonate elements (Ca, Mg) with carbonate content; while Fe and magnetic susceptibility displayed changes in relation to inorganic matter content. Remarkably, the findings reflected the global 8200 cal BP and 4200 cal BP events, along with their environmental effects, within the Transylvanian Basin. There was mediaeval lakebed cleaning around 500300 cal BP, during which the deeper of two water layers was contaminated with more recent materials. The shallower water layer is connected with the modern water circulation, which reduces the apparent age of peat samples taken from its immediate vicinity.

Groundwater is utilized as a clean water source including in Pelauw and Kariu Villages. Drilling and excavating are frequent techniques utilized in the construction of wells that serve as sources of groundwater. As a result of the ocean encircling the majority of this area, salinity may infiltrate wells. Consequently, the purpose of this study was to ascertain whether seawater intrusion had occurred in 12 nearby wells. Major ion tests were carried out in the lab, while surveys and measurement fields were carried out for the sampling procedure. Ion Cl, EC, TDS, Simpson ratio, and BEX data are used in the analysis to determine whether seawater intrusion is present. Additionally, the Piper diagram is used to categorize different types of water based on the outcomes of the main ion test. The findings indicated that Cl-, EC, and TDS levels have increased at a number of the sampling sites. At point A09, there is an indication of seawater intrusion based on the BEX values, which shows a negative number. The majority of the well water, as determined by a water classification analysis using the Piper diagram, is of the calcium carbonate type. Meanwhile, the remaining portion is separated into the calcium sulfate and sodium bicarbonate types.

Over 1/3 of the Earth’s human population relies on dryland ecosystems for food and water resources. While these ecosystems are highly sensitive to changes in climate, we lack observational data as to how changes in hydrology influences plant communities. Paleoecological data for southern Arabia show woodland communities transitioned to more dry-adapted herbaceous plants, which suggests rainfall decreased across the Holocene. To assess relationships between hydrology and ecology, we employed leaf wax n-alkane distributions, δ13Cwax, and δDwax records from rock hyrax (Procavia capensis) middens in Dhofar, Oman. The biomarker properties allowed reconstruction of changes in C3/C4 vegetation and local moisture availability, in tandem with community changes represented by a published pollen record. To constrain interpretations, n-alkane analyses were conducted on herbarium specimens of leaves collected in Dhofar. For the modern specimens, xeric plants typically contained longer homologues than mesic plants. Across the fossil middens (4,038–109 cal yrs BP), the proportions of plant-wax homologues do not show major changes, and thus do not suggest a shift between xeric versus mesic plants. Similarly, δ13Cwax values indicate little or no change in the distributions of C3 and C4 vegetation. Limited δDwax data from the middens confirm overall drying occurred into the late Holocene, punctuated by a wetter pulse at ∼1.6 ka. Taken together, plant wax distributions and isotope data indicate changes in moisture availability across the late Holocene did not alter the structural composition of the plant communities and that the proportion of C3/C4 vegetation remained stable. We infer vegetation changes associated with late Holocene drying involved reshuffling of community composition and not major changes in vegetation structure. Additionally, this study demonstrates that leaf wax n-alkanes from rock hyrax middens provide a method to reconstruct changes in climate and vegetation in dryland ecosystems where other archives are scarce.

Abstract Antecedent hydrological conditions are recorded through the evolution of dissolved lithium isotope signatures (δ7Li) by juxtaposing two storm events in an upland watershed subject to a Mediterranean climate. Discharge and δ7Li are negatively correlated in both events, but mean δ7Li ratios and associated ranges of variation are distinct between them. We apply a previously developed reactive transport model (RTM) for the site to these event‐scale flow perturbations, but observed shifts in stream δ7Li are not reproduced. To reconcile the stability of the subsurface solute weathering profile with our observations of dynamic stream δ7Li signatures, we couple the RTM to a distribution of fluid transit times that evolve based on storm hydrographs. The approach guides appropriate flux‐weighting of fluid from the RTM over a range of flow path lengths, or equivalently fluid residence times. This flux‐weighted RTM approach accurately reproduces dynamic storm δ7Li‐discharge patterns distinguished by the antecedent conditions of the watershed.

Research projects in the Shashe-Limpopo Basin have witnessed significant developments in the use of conceptual frameworks and multidisciplinary approaches such as electrochemical and geochemical sequencing. Accordingly, there is now data to question the widely accepted model for the evolution of Mapungubwe State (AD 1200–1300) which argues that favourable and unfavourable regional climatic weather conditions (wet and dry) lead to the rise and decline of the State. Floodplain agropastoral activities in the middle Limpopo Valley are a widely assumed hypothesis, despite the general absence of relevant chemical signatures and archaeobotanical data. This article discusses soil sequences and chemical analyses (Inductively Coupled Plasma Atomic Emission Spectroscopy and Redox Potential) to provide a palaeoenvironmental record of water regimes in relation to Mapungubwe. Findings confirm that geochemical techniques can be used to model or predict aquifer behaviour and the occurrence of groundwater. And, as such, highlighting the need for conservation planners to carefully consider integrative scientific tools to improve conservation practices of archaeological heritage and overexploitation of groundwater resources. Although more data is required, the results obtained allows researchers to begin reframing questions concerned with the links between changing water regimes and social changes, in this case relating to the decline of Mapungubwe. The understanding is important for the management and conservation of the Mapungubwe World Heritage site and surrounding landscape.

The present study gathers mineralogical and isotopic geochemical data of 45 soil samples collected from the La Guardiense and Cantina di Solopaca wineries (Southern Italy) in order to provide useful information for the geotraceability of Falanghina white wine terroir. Mineralogical analyses show the ubiquitous presence of quartz, frequent and moderate contents of feldspars and phyllosilicates (i.e., illite/mica, kaolinite, and smectite). Rhizosphere soils from La Guardiense vineyards show a strontium isotope signature (87Sr/86Sr) ranging from 0.708604 to 0.711234 (average 0.710334; 1σ = 0.000943; n = 7) for the total fraction and a narrower range (from 0.706907 to 0.708807; average 0.708120; 1σ = 0.000641; n = 7) for the bioavailable one. For the rhizosphere soils collected from the vineyards of Cantina di Solopaca winery, 87Sr/86Sr ratios range from 0.708268 to 0.712413 (average 0.710145; 1σ = 0.001622; n = 8) and from 0.707968 to 0.709157 (average 0.708384; 1σ = 0.000409; n = 8) for the total and the bioavailable fraction, respectively. Actually, the bioavailable Sr fraction shows a narrower range of 87Sr/86Sr ratios compared to that of the total fraction, making the former more suitable for any study of wine traceability.

Abstract We perform a set of reactive transport simulations in three‐dimensional fracture networks to characterize the impact of geochemical reactions on flow channelization. Flow channelization, a frequently observed phenomenon in porous and fractured subsurface rock formations, results from the spatially variable hydraulic resistance offered by a geological structure. In addition to geo‐structural features such as network connectivity, geometry, and hydraulic resistance, geochemical reactions, for example, dissolution and precipitation, can dynamically inhibit or enhance flow channelization. These geochemical processes can change the fracture permeability leading to increased flow channelization, which are localized connected regions of high volumetric flow rates that are seemingly ubiquitous in the subsurface. In our simulations, fractures partially filled with quartz are gradually dissolved until quasi‐steady state conditions are obtained. We compare the flow field's initial unreacted and final dissolved states in terms of flow and transport observations. We observe that the dissolved fracture networks provide less resistance to flow and exhibit increased flow channelization when compared to their unreacted counterparts. However, there is substantial variability in the magnitude of these changes which implies that the channelization strongly depends on the network structure. In turn, we identify the interplay between the particular network structure and the impact of geochemical dissolution on flow channelization. The presented results indicate that geological systems that have been weathering or reactive for longer times in older landscapes are likely to have increased flow channelization compared to their equivalent but younger counterparts, which implies a time dependence on flow channelization in fractured media.

Abstract The Pleiades Volcanic Field is made up of some 20 monogenetic, partly overlapping scoria and spatter cones, erupted in the last 900 ka, cropping out from the ice close to the head of the Mariner Glacier in northern Victoria Land, Antarctica. Erupted products vary from hawaiite to trachyte, defining a complete mild Na‐alkaline differentiation trend. Mafic samples are characterized by multi‐elemental patterns typical of OIB magmas, moderately low 87Sr/86Sr (0.7037) and high 143Nd/144Nd (0.51284), with a clear within‐plate affinity, indicating a subcontinental lithospheric source. With increasing SiO2, 87Sr/86Sr ratios increase up to 0.7052 and 143Nd/144Nd decrease to 0.51277, supporting the hypothesis of open‐system evolution, with significant crustal assimilation during fractional crystallization. The erupted volume of most evolved products (∼7 km3), according to fractionation models, suggests that primitive magmas should have been more than 10 times larger, indicating the occurrence of a large magma plumbing system, unexpected for a volcanic field of monogenetic scoria cones. The occurrence of a complete fractionation trend with large magma chambers and large assimilation rate is unusual, if not unique, among the alkali basaltic volcanic fields and it is matched by a climax of activity during the last glacial maximum (30 ka), as indicated by new 40Ar‐39Ar ages (30 ± 3 ka and 25 ± 2 ka) for samples from the two most prominent edifices. Therefore, we hypothesize a role of a thick ice cap in suppressing eruptions and ultimately leading to prolonged magma residence time in the subsurface, favoring significant fractionation coupled with unusual high rates of crustal assimilation.

The role of subglacial abrasion in sustaining subglacial microbiomes is an area of growing interest. It is likely that subglacial abrasion produces a range of bio-utilisable compounds, some released from fluid inclusions in the confines of the mineral matrix and some produced via the surface free radicals that crushing produces in a variety of different minerals. As yet, the geochemical reactions which are initiated by abrasion remain poorly understood. This is largely because of the multiple potential sources and sinks of free radicals that occur in even the most simple of multi-mineralic system during crushing and subsequent wetting of the mixture. We illustrate this assertion by conducting a series of laboratory experiments where common, “simple” silicate minerals, such as quartz and feldspar, are abraded and incubated with ultra-pure water. Gaseous reaction products included CH4, H2 and CO2. The concentrations of major ions (including Na+, K+, Mg2+, and Ca2+), dissolved silicate, dissolved iron and pH of the solution during incubation are reported. These results were used to calculate HCO3− in solution and the saturation index with respect to various minerals using PHREEQCi. We found that abrasion of silicates produces bio-available gases and has the potential to increase the concentration of various weathering products in solution. Further, we found that even trace amounts of carbonates, an impurity in many natural rocks and minerals, may significantly affect the reaction products, making it challenging to concretize the reactions taking place. These results highlight the importance of conducting abrasion experiments utilising natural samples to better understand how apparently negligeable changes in mineralogy might affect the reaction products of abrasion and crushing.

Detrital and volcanic-detrital rocks from the Ifni Buttonhole and Lakhssas Plateau were analyzed to determine their provenance, compositional maturity, and alteration source. Geochemically, the sediments were classified as arkoses, lithic arenites, grauwackes, sandstones, lithic arenites, and Fe-rich sands, indicating low compositional and mineralogical maturity. A high average SiO2 concentration and low Al2O3 were consistent with a low abundance of shale and clay components. The geochemical signatures of the detrital and volcano-detrital (RDVD) rocks indicate that they have undergone a moderate to low degree of chemical alteration. The CIA study also suggests that the granitic, granodioritic rocks represent the source provenance which, during weathering and transport, supplied the detritus to the supra-crustal units. The major trace element data suggest that these rocks are largely derived from felsic igneous rocks, namely granitoids, with a minor contribution from intermediate sources. The carbonate rocks do not represent a wide variety of facies: dolomitic limestone, calcareous limestone, and calcaro-dolomitic chert. Calcitic and dolomitic samples show a linear increase in SiO2, regardless of their CaO/LOI ratio values, which remain relatively constant. The highest SiO2 contents are observed in the calc-dolomitic chert. Geochemical analysis of RDVD from the Ifni buttonhole determined their origin, maturity, and alteration. Major oxides decreased with higher silica content, indicating quartz control. Samples, formed under semi-arid conditions, show maturity under stable deposition. They suggest a felsic, recycled source, with moderate alteration and zircon enrichment during recycling. In the study area, limestones and dolomites serve as materials applicable in the building sector, suitable for all types of concrete. The Taliwine Formation harbors Lower Cambrian dolomites and limestones, ideal for mosaic aggregates. Described as variable in color, compact, homogeneous, very hard, and resistant to alteration, the plutonic rocks form prominent peaks. They exhibit both subalkaline characteristics in granitoids and an alkaline trend in dolerite dykes. Most samples display minimal alteration, indicating the reliability of their major element compositions for geochemical analyses. These granitoids constitute valuable deposits for ornamental and building rock purposes.

This paper deals with the issue of changing the conditions of the geographical environment in the postglacial and Holocene in the central part of the Karelian Isthmus. Toward paleogeographic reconstruction, a survey of the sediments of the bottom of Lake Krasnoye (Leningrad Oblast, Russian Federation) was conducted, since the lake deposits represent a reliable source of information about natural events from the past. A large amount of data obtained by X-ray fluorescence analysis of the core sample was analyzed, a lithostratigraphic description of the sediments was carried out and geophysical characteristics of the bottom sediments were interpreted. They were divided into several units that differed in the number of properties and reflected different sedimentation conditions. In the reconstruction of the past natural environment, special attention is paid to paleoclimatic and paleosedimentological issues.

The Huoshaoyun deposit in the Karakorum area of NW China is the world’s largest zinc-lead carbonate ore deposit. Here we investigate the genesis of the mineralization based on multiproxy investigations. The deposit contains zinc-lead carbonate and sulfide minerals, with smithsonite (Smt), cerussite (Cer), and sulfides accounting for 85%, 10%, and 5% of the total lead and zinc resources, respectively. Three ore-forming stages, involving Smt, Cer, and sulfides ores were summarized. The Smt mineralization is characterized by veined, massive, and stratified Smt forming horizontal sedimentary layered ore and vertical feeder veins similar to the SEDEX-type deposits. The sulfide and Cer veins display typical hydrothermal characteristics and are superimposed on the massive Smt ores. The Smt ores show high Li, Be, Cr, Y, Ba, Nd, Yb, and Zr contents, whereas the Cer veins have extremely high Sr contents (up to 3814–9174 ppm) and low Zr contents (less than 0.01 ppm). Galena and sphalerite show higher Cd concentrations compared to Smt and Cer ores.The Smt ores differ with different spatial locations, with Smt ores formed at the vent have δ66Zn values of +0.15‰ to +0.21‰, the massive Smt formed close to the vent show a value of +0.13‰, and those formed away from the vent show a value of 0.05‰, all values being close to 0. The sulfides have δ66Zn values of −0.09‰ to +0.04‰. The C-O isotopes of Smt ores are similar to both altered and unaltered host limestone, suggesting that the limestone was a potential source for carbon and oxygen. Quartz with veined Smt shows magmatic signatures with δ18OVSMOW of +1.14‰ to +2.23‰, high Pb (115–401 ppm) and Zn concentrations (390–997 ppm), whereas quartz associated with sulfide has meteoric fluid signature with the lowest δ18OVSMOW (−14‰ to −10.7‰), low Pb (11.6–49.0 ppm) and Zn (18.1–72.8 ppm) concentrations. The temperature of equilibration computed based on oxygen isotope fractionation between Smt and coeval quartz indicate a dual source with that of quartz derived from an aqueous fluid, whereas the source for Smt might involve CO2 or HCO3−.We trace multiple metallogenic stages for this deposit including exhalation, hydrothermal deposition, and fault-controlled sulfide vein formation. The largest orebody (III-1) preserves a 16 Mt reserve of Zn and was formed by crust-mantle interaction at ca. 195 Ma in the early development of the Linjitang post-arc rift system. Fluid convection, zinc enrichment driven by granitic magma, volcanic activity, and karst alteration induced by acid rain in a lagoonal environment promoted ore enrichment.

Abstract Natural gas fields with economic helium (>0.3 He %) require the radioactive decay of crustal uranium (U) and thorium (Th) to generate He and tectonic/structural regimes favorable to releasing and concentrating He. An unknown is determining the role of faults and structural features in focusing deep‐seated He sources on shallow accumulations. We tested the correlation between high‐He wells (n = 94) and structural features using a new high‐resolution aeromagnetic survey in the Four Corners area, USA. A depth‐to‐basement map with basement lineaments/faults, an intrusion map, and a flattened basement structural high map were created using Werner deconvolution algorithms by combining magnetic, gravity, and topography data with magnetic and gravity depth profiles. We show quantitatively (via analysis of variance) that a non‐random process controls the relationship between He (>0.3%) and both basement faults and intrusions: 88% of high‐He wells occur

To identify potential heavy minerals in the Mbiame floodplain in the Northwestern region of Cameroon, geochemical and petrographical data from alluvial deposits were utilized. The grains are mixed with inclusions of zircon and ilmenite, and the megacrysts come from felsic to intermediate igneous rocks like old basalt-andesite and magmatic gneiss. The Mbiame region lies between latitudes 6° 8’ and 6° 24’ N and longitudes 10° 39’ and 10° 57’ E, East of Mount Oku. One of the principal volcanic massifs on the Cameroon Volcanic Line (CVL), Mt. Oku is situated over a basement composed of migmatites, biotite diorites, and Pan-African granite-gneisses that date back to 600 Ma.The Mbiame Floodplain is located in the Pan African Fold Belt, which is made up of the Benin-Nigeria belt, which is a component of the Central African Fold Belt, and the Trans-Saharan belt. Between the Congo and West African cratons is a heavily eroded and deformed combination of Neoproterozoic plutonic and volcanic arcs and Paleoproterozoic micro-continents. The Central Cameroon Shear Zone serves as the primary lineament for the Pan African Orogeny, which is structurally separated into the Northwestern Cameroon Domain (NWC), the Adamawa-Yade Domain (AYD), and the Yaounde Domain (YD) in Cameroon.The field work was carried out during the dry season. During the field campaign, numerous bulk sediments were sampled from three (03) pits of vertical lithological succession along the left terrace of the Mbiame plain and twelve (12) were selected for laboratory analyses. The criteria for sample collection were based on texture (grain size) and color parameters. To identify the heavy minerals in the sediments and to understand the source of the sediments, the selected 12 bulk samples from the different layer of the pits were dried and sieved for heavy mineral determination. Heavy mineral separation was performed on about 2 g of the concentrate using bromoform liquid and the retained heavy minerals were mounted and observed under a petrographic microscope for optical properties identification.Twelve (12) bulk sediment samples weighing 100 g each were ground up in a mild steel pulverizer before being examined for major and trace elements. At Acme Analytical Laboratories Ltd., Vancouver, Canada, the geochemical study was carried out utilizing a combination of mass spectrometry (ICP-MS) for trace elements and inductively coupled plasma emission spectrometry (ICP-ES) for significant oxides. Lithium metaborate/tetraborate (LiBO2/Li2B4O7) flux was combined with 0.2 g of sample in crucibles, and the mixture was fused in a furnace. After the beads cooled, they were digested in ACS-grade nitric acid and then subjected to ICP-MS analysis. To calculate loss on ignition (LOI), a sample split at 1000 °C was ignited, and the weight loss was then measured. Data of this paper are further presented and discussed in Etutu et al. [1].

Geochemical data are compositional in nature and are subject to the problems typically associated with data that are restricted to the real non-negative number space with constant-sum constraint, that is, the simplex. Geochemistry can be considered a proxy for mineralogy, comprised of atomically ordered structures that define the placement and abundance of elements in the mineral lattice structure. Based on the innovative contributions of John Aitchison, who introduced the logratio transformation into compositional data analysis, this contribution provides a systematic workflow for assessing geochemical data in a simple and efficient way, such that significant geochemical (mineralogical) processes can be recognized and validated. This workflow, called GeoCoDA and presented here in the form of a tutorial, enables the recognition of processes from which models can be constructed based on the associations of elements that reflect mineralogy. Both the original compositional values and their transformation to logratios are considered. These models can reflect rock-forming processes, metamorphism, alteration and ore mineralization. Moreover, machine learning methods, both unsupervised and supervised, applied to an optimized set of subcompositions of the data, provide a systematic, accurate, efficient and defensible approach to geochemical data analysis. The workflow is illustrated on lithogeochemical data from exploration of the Star kimberlite, consisting of a series of eruptions with five recognized phases.

This paper documents the provenance and palaeoclimatic conditions of the Cretaceous Lumshiwal Formation near the western margin of the Indian plate in the Surghar Range, northwest Pakistan. The combined techniques of petrography, X-ray diffraction (XRD), and bulk rock geochemistry were utilized to reveal the source and mineral-geochemical composition and sandstone type. The petrographic analysis of the sandstones confirms the dominance of quartz, feldspar, and rock fragments, with subordinate occurrences of muscovite, magnetite, and hematite. Heavy minerals consist of tourmaline, titanite (sphene), rutile, cassiterite, monazite, and zircon. The cementing material includes ferruginous clays, jarosite, glauconite, calcite, minor dolomite, gypsum, and silica. The modal composition plot of the sandstones falls into arkose to sub-arkose, with a few lithic arkose varieties. Lithic fragments mainly include granite, with a minor occurrence of granitic gneiss, chert, phyllite, and quartz mica schist. The discriminatory provenance diagram of the sandstones suggests a transitional continental provenance. The bulk rock geochemistry of the sandstones reveals the presence of SiO2, TiO2, Al2O3, Fe2O3, FeO, MnO, CaO, MgO, Na2O, K2O and P2O5. The petrographical mineral findings were corroborated with XRD, SEM, and bulk rock geochemistry analysis (major element concentrations and their ratios), which collectively all confirm a felsic igneous source. The tectonic discrimination diagram (SiO2-log K2O/Na2O wt %) implies a dominant influx of sediment sourced from the passive continental margin of the uplifted Gondwana Indian plate. Terrigenous sediments found in the Lumshiwal Formation are interpreted to have been derived from granites and granitic gneisses of the Indian Shield. The palaeo-weathering index, including the chemical index of alteration (CIA) and the chemical index of weathering (CIW) of the Lumshiwal Formation confirms a low to moderately weathered source area. The climate discrimination plot (SiO2 versus Al2O3 + Na2O + K2O) shows that humid to semi-humid climatic conditions during the deposition of the Lumshiwal Formation.

Abstract Understanding the age and dynamics of the overriding plates allows an assessment of competing subduction initiation hypotheses. The Izu‐Bonin‐Mariana margin in the Western Pacific is a key example of initiation and hence it is important to constrain the age and origin of the oldest igneous crust of the supra‐subduction Philippine Sea Plate. We present geochronological and geochemical data of igneous rocks from the oldest ocean basins of the Philippine Sea Plate: the West Philippine and Palau Basins. Basalts from these basins have enriched geochemical characteristics similar to the EM‐2‐like mantle component found in OIB‐like basalts associated with the Oki‐Daito mantle plume. Ages of basalts from the northernmost West Philippine Basin (WPB) and the Palau Basin range from 43.5 to 50.5 Ma, which is similar to the oldest samples associated with the Oki‐Daito mantle plume (48–50 Ma). This implies that the plume contributed to magmatism from the onset of basin formation. It also provides support for the proposition that rifting of the Mesozoic arc terrane and subsequent seafloor spreading of the WPB was triggered by the arrival of the Oki‐Daito mantle plume at the base of the lithosphere. The age of these Philippine Sea Basins implies that only the Mesozoic Daito Ridge Group and the Gagua Ridge existed as Philippine Sea Plate crust before subduction initiation. A major fault activity after 37 Ma in the northernmost WPB demonstrates that careful reconstruction of the Eocene Philippine Sea Plate is critical to understanding plate dynamics during subduction initiation in the Western Pacific.

Abstract This study provides a comprehensive characterization of various hydrothermal systems in Southern Peru ranging from the faulted Precordillera's steep topography up to the volcanic High Cordillera (>4,000 m asl). The objective is to investigate thermal anomalies that may potentially serve as new geothermal resources. Our integrated approach combines: (a) geochemistry from 14 hot springs sampled throughout the Tacna region, and (b) 3D numerical modeling of coupled groundwater and heat transfer considering topography and faults embedded in homogeneous permeability. Water and gas analysis indicates that the springs located near volcanoes discharge Na‐K‐Cl waters with high temperatures (>87°C), high Total Dissolved Solid concentrations (TDS >3,452 mg/L), and free gases dominated by CO2 (>90 vol%). Springs located along the regional faults in the Precordillera discharge Ca‐SO4 and Na‐K‐Cl waters with moderate temperatures (27–53°C), intermediate TDS concentrations (464–2,458 mg/L), radiocarbon ages between 1.4 and 7.9 kyr, and free gases dominated by N2 (>95 vol%). The Aruma springs, which are located at the transition between the High and the Precordillera, display intermediate characteristics. Numerical models accurately replicate the locations and temperatures of the fault‐related springs only for permeable faults (>10−14 m2), revealing the creation of 100‐km long thermal plumes along faults, locally rising up the 150°C‐isotherm to about ∼1,000 m below the surface. This approach clearly distinguishes the spring origins, which are volcanic in High Cordillera and tectonic in Precordillera. Moreover, we highlight that steep topographic gradient and permeable reverse faults in the Andean forearc may generate considerable thermal anomalies, opening perspectives for the geothermal exploration.

Abstract The Sr‐Nd‐Hf‐Pb isotope geochemistry of the Late Miocene Tunceli Volcanics suggests that they are the products of mixed asthenospheric and lithospheric mantle melts. The combined elemental and mineral chemistry data additionally indicate that a pyroxenite component of lithospheric origin is involved in their genesis. Calculations favor melting depths of ∼2 GPa for the Tunceli lavas, that is, deeper than the current lithosphere‐asthenosphere boundary beneath Eastern Anatolia. Geochemical data suggest that during regional Neo‐Tethyan subduction, dense (i.e., pyroxenite‐bearing) domains formed by progressive melt intrusion into the lower lithosphere resulted in gravitational instabilities. This unstable density configuration eventually led to the foundering of the eastern Anatolian lithosphere in the Late Miocene, resulting in progressive melting of fusible pyroxenite‐bearing domains at asthenospheric depths. We demonstrate that these pyroxenitic melts mixed with ambient asthenospheric melts and generated the Tunceli lavas.

Granitoid intrusion of several provinces on Sumatra is correlated with Southeast Asia tectonics that have occurred since the Permian. Granites from several volcanic arc provinces are located along the western part of Sumatra Island and are found near Bukit Barisan. This study describes the geochemical character of granitoid from the Tanggamus region and its surroundings near the Bukit Barisan cluster. After megascopic description in the field, major oxides, trace elements, and rare earth elements in rock samples were measured using X-ray fluorescence and inductively coupled plasma-mass spectrometry devices. The samples were intermediate to acidic intrusive rocks with SiO2 ranging between 61.35% and 75.29%. The rocks can be described as diorite to granodiorite and were formed as a result of subduction processes. The granitic rock samples showed I-type features of A/CNK value

Identifying the sources and weathering degree of sediments in the northern deserts of China is crucial to understand the evolution of the Asian monsoon system and corresponding induced changes in surface processes. Great progress has been made in the reconstruction of paleoclimate and paleoenvironment from the Early Holocene onwards based on chronostratigraphy and proxies of aeolian sedimentary sequences in the Mu Us Desert (MUD). However, previous studies have given rise to some controversial over the timing of the Holocene optimum period, and there is a scarcity of studies on the sediment provenance evolution of the desert during the Holocene and its internal relationship with the East Asian summer (EASM) and winter (EAWM) monsoons. Here, we provide new elemental geochemical data from a fluvial–aeolian sedimentary sequence in the southern MUD; we then combine these data with other available elemental data and hydroclimatology information to investigate the characteristics of sediment source evolution and their possible connection with the EASM and EAWM on the southern margin of the MUD-desert/loess transition zone since the latter part of the Early-Holocene. The elemental composition and geochemical characteristics of the studied sedimentary sequence differed markedly in the periods before and after 6.4 ka BP, suggesting a change in the source of the sediments across this boundary. From the late Early-Holocene (10.6 cal. ka BP), sediments were dominated by the chemical weathering products of local source material, with a gradual increase in chemical weathering over time, indicating a gradual strengthening of the EASM; the EASM reached its peak Holocene strength at 8.4–6.4 ka BP, accompanied by a moderate level of chemical weathering. After 6.4 ka BP, with the weakening of monsoon precipitation, the EAWM began to strengthen, and long-distance transport of source material from the west and northwest increased; however, chemical weathering of local source material driven by the EASM remained dominant until 4.0 ka BP. After 4.0 ka BP, the EAWM became dominant, and sediments showed strong sedimentary cycles, mainly transported from long-distance sources by aeolian activity, and the MUD became an important sedimentary sink for the northern-central deserts. After 0.7 ka BP, the sediments in the MUD became a mixture of different-age sediments due to river scouring and the transport of pre-existing sediments along the shoreline. Collectively, the elemental geochemical and other proxy data from Holocene sediments on the southern margin of the MUD record an inverse relationship between the EASM and EAWM; these two monsoonal circulations have alternated in their control of the sedimentary source characteristics and geomorphological environmental evolution processes across the southern margin of the MUD during the Holocene.

Abstract High‐resolution records from past interglacial climates help constrain future responses to global warming, yet are rare. Here, we produce seasonally resolved climate records from subarctic‐Canada using micron‐scale measurements of oxygen isotopes (δ18O) in speleothems with apparent annual growth bands from three interglacial periods—Marine Isotope Stages (MIS) 11, 9, and 5e. We find 3‰ lower δ18O values during MIS 11 than MIS 5e, despite MIS 11 likely being warmer. We explore controls on high‐latitude speleothem δ18O and suggest low MIS 11 δ18O values reflect greater contribution of cold‐season precipitation to dripwater from longer annual ground thaw durations. Other potential influences include changes in precipitation source and/or increased fraction of cold‐season precipitation from diminished sea ice in MIS 11. Our study highlights the potential for high‐latitude speleothems to yield detailed isotopic records of Northern Hemisphere interglacial climates beyond the reach of Greenland ice cores and offers a framework for interpreting them.

Oceanic igneous rocks throughout the Altai-Sayan Fold Belt (ASFB) in central-southern Siberia are often considered to be late Precambrian–early Paleozoic accreted elements of oceanic crust – often of uncertain paleogeographic or geodynamic origin. We explore the role of suprasubduction zone settings in the formation of different ASFB terranes. Our study offers a non-accretionary perspective on the tectonomagmatic development of basalt-bearing units in the ASFB on the example of the forearc terrane of the Ediacaran–early Cambrian Tannuola-Khamsara island arc (herein termed Sayan-Tuvan forearc zone). We describe the geochemistry, structural geology, and stratigraphic relations of basalts of the Aldynbulak, Uttug-Khaia, and Chingin formations, which are integral parts of the Sayan-Tuvan forearc zone. The Aldynbulak basalt samples mainly fall in the compositional fields of ocean island basalts and enriched mid-ocean ridge basalts (E-MORB) and likely derived from a deep mantle source. The Uttug-Khaia and Chingin basalts are N- and E + T-MORB-like basalts, carrying forearc geochemical signatures. Specifically, the Chingin Formation contains boninite dikes and is associated with a boninite-bearing ophiolite. Boninites are commonly associated with forearc magmatism and thus a forearc formation setting is likely. Tectonic and stratigraphic considerations imply that the Aldynbulak basalts formed first, followed by the Uttug-Khaia and later the Chingin basalts and boninites. A schematic model, involving decompression melting of the mantle, is proposed for the development of the studied forearc basalt suites that are linked with the growth of the Tannuola-Khamsara island arc system 580–540 million years ago.

Sediment geochemistry is one lens through which lake sediments are studied to reconstruct local and regional environmental processes. The measurement of sediment elemental composition has historically relied on expensive and destructive methods that limit the spatial and temporal scale of study. Micro-X-ray fluorescence (µXRF) core scanning offers a non-destructive, high-resolution alternative, but its results (i.e., intensity expressed as counts per second) are considered semi-quantitative and comparison among sites requires calibration. Calibration methods are emerging, although they are not yet widely employed and require further assessment of their efficacy. Using 135 sediment samples from 48 lakes across Canada, we assessed the congruence between µXRF and conventionally measured element compositions with various normalization and calibration techniques. Normalization of µXRF data to common proxies (e.g., Ca, Si, Ti, coherence:incoherence ratio, and total counts per second) often improved correlations between µXRF and conventional data, but increases were modest and not consistent for all elements. Our results suggest that µXRF normalization techniques should be applied cautiously, as no proxy represents a “one-size-fits-all” solution. The performance of multivariate log-ratio calibration (MLC) was more consistent, yielding moderate to strong improvement of the correlations between reference and predicted element concentrations. Random forest regression models outperformed partial least squares regression models for almost all elements. MLC may be applied where knowledge of elemental concentration is of great importance, or when comparing across multiple sites with diverse sediment geochemistries. Overall, our results reinforce uncalibrated µXRF core scanning as a strong investigative tool for measuring sediment geochemistry. Although calibrated µXRF data shows promise, conventional methods for measuring sediment geochemistry are still necessary for comparing element concentrations with sediment quality guidelines.

Two fully cored boreholes, the Rødryggen-1 and the Brorson Halvø-1, were drilled in Wollaston Forland, North-East Greenland, in 2009 and 2010, respectively. The objective was to test the stratigraphic development of the Upper Jurassic – Lower Cretaceous mud-dominated succession in two different settings within the same fault block of a developing half-graben: centrally (Rødryggen-1 borehole) and near the uplifted crest of the rotating fault block (Brorson Halvø-1 borehole). The drilled deposits are equivalent to the principal petroleum source-rock sequence of the petroliferous basins of North-West Europe, Siberia, and basins off eastern Canada and provide a new record of an important phase of marine deoxygenation in the proto-North Atlantic region.

The Mongolia-Okhotsk tectonic regime had a significant impact on the tectonic evolution of Northeastern (NE) China. However, there is no consensus on the role of this regime in the geological evolution of the Xing’an Massif during the late Mesozoic. This article presents the results of zircon U–Pb geochronology, whole-rock major and trace-element geochemistry, and zircon Hf isotopic compositions for granites in the Haobugao area of the southern Great Xing’an Range, NE China, to determine their petrogenesis, source, and tectonic setting. The zircon U–Pb ages indicate that the granites crystallized at 152.7 ± 0.5 Ma. The granites exhibit high SiO2 (70.75–73.19 wt%) and K2O + Na2O (8.00–8.65 wt%) contents and extremely low MgO (0.40–0.59 wt%) and TiO2 (0.24–0.33 wt%) contents. They belong to the metaluminous, high-K calc-alkaline, and ferroan series, with mostly right-inclined REE curves, flat heavy rare earth element patterns, high 10,000 Ga/Al ratios, and intensely negative Eu anomalies. The Zr/Hf ratios are 24.2–27.7, Nb/Ta ratios are 6.4–8.9, and Y/NbN ratios are >1.2. These characteristics suggest an A2-type granite affinity. The zircon εHf values of the rocks range from +5.62 to +9.12, corresponding to T DM2 values of 621–906 Ma, indicating that juvenile materials in the Neoproterozoic may be a source of these granites. Geochemically, these Late Jurassic A2-type granites are similar to those from post-collision extension settings. The primary magma was likely derived from the partial melting of a delaminated region of the lower crust.

The use of mudbricks in Early Iron Age ramparts is an uneven feature of defensive architecture on the Iberian Peninsula. The use of mudbricks as a building material has been linked to the arrival of Levantine building traditions with the Phoenicians, and its appearance among local societies varies between the eighth and sixth centuries BC according to the public or domestic nature of the structures. In this article, we present the geoarchaeological analyses of the mudbricks used in constructing one of the defensive towers or bastions at Villares de la Encarnación (Caravaca de la Cruz, Spain). This site, endowed with two complex fortification lines and towers, is one of the main settlements for understanding the development of the Early Iron Age among the inland and mountain communities of the region. The analytical program includes wavelength dispersive X-ray fluorescence, CHN elemental analysis, and thin-section petrography and provides new data about soil procurement and manufacturing choices. These results highlight the technical and social complexity behind mudbrick constructions and the adoption of new earthen practices among Early Iron Age communities in order to build more imposing and elevated towers that might convey an image of the power and strength of these inland settlements.

The Carboniferous-Permian coal measure strata in the Qinshui Basin exhibit highly lithium (Li) enrichment, with substantial exploitation potential. To further explore the enrichment mechanism of lithium in coal measure strata, the No. 15 coal of the Taiyuan Formation from the Gaoping mine is taken as the research object, and its mineralogical and geochemistry characteristics are evaluated using optical microscopy, X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry, X-ray fluorescence, and infrared spectral. The results show that the No. 15 coal is semi-anthracite coal with low moisture, low ash, low volatility, and high sulfur. Organic macerals are primarily vitrinite, followed by inertinite, and liptinite is rare; the inorganic macerals (ash) are dominated by clay minerals (predominantly kaolinite, cookeite, illite, and NH4-illite), calcite, pyrite, quartz, siderite, gypsum, and zircon. The average Li content in the coal is 66.59 μg/g, with higher content in the coal parting (566.00 μg/g) and floor (396.00 μg/g). Lithium in coal occurs primarily in kaolinite, illite, cookeite, and is closely related to titanium-bearing minerals. In addition, Li in organic maceral may occur in liptinite. The No. 15 coal was formed in the coastal depositional system, and the deposition palaeoenvironment is primarily a wet–shallow water covered environment in open swamp facies; the plant tissue preservation index is poor, and aquatic or herbaceous plants dominate the plant type. The reducing environment with more terrestrial detritus, an arid climate, and strong hydrodynamic effects is favorable for Li enrichment in coal. The results have important theoretical significance for exploring the enrichment and metallogenic mechanisms of Li in coal.

Hydrothermal activity is widespread in sedimentary basins, but its dual effects (chemistry and temperature) on shale reservoirs are rarely discussed. In this research, we systematically collected 33 well core samples from Q1 to Q9 units in Gulong Sag, Songliao Basin, and analyzed them using a variety of analytical techniques, including a field emission scanning electron microscopy (FE-SEM), an energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), and stable C-O isotopes. Combined with the collected vitrinite reflectance (Ro), total organic carbon (TOC), and soluble hydrocarbon content data, which is the sum of free oil (pyrolysis S1) and sorb oil content (pyrolysis S2), the results show that (1) Q4 and Q8 units have large amounts of hydrothermal minerals, and its C-O isotope obviously shifts to negative, which implied those units are the main hydrothermal fluid influence area; (2) the hydrothermal activity occurred in the late depositional period of Q1–Q9 units such that its geochemistry has little effect on the proliferation of algae blooms, but its high temperature calculated by δ18O temperature formulas (around 208 °C) promoted the organic matter maturation process around Q4 and Q8; and (3) the overpressure caused by hydrothermal activity protected the shale reservoir and minimized the decrease in mineral reservoir brittleness index caused by hydrothermal fluid influence. We suggest that the shale reservoir affected by hydrothermal fluid will become a good geology “dessert”, and its upper and/or lower bounds can form an engineering “dessert” due to the precipitation of large amounts of brittle carbonate minerals.

The Lujiang–Chuzhou Metallogenic Area is an important component of the Middle–Lower Yangtze River Valley Metallogenic Belt. Despite being an important copper–gold deposit in this area, the Shanlixu skarn Cu-Au deposit has not yet been systematically studied. According to LA-ICP-MS zircon U-Pb dating, the quartz monzonite porphyry from the Shanlixu deposit is aged 137.5 ± 1.7 Ma: while it differs from the timing of the magmatism and related mineralization in the Lujiang–Chuzhou Area, it is consistent with magmatic activity elsewhere in the Middle–Lower Yangtze River Valley Metallogenic Belt. The Ce4+/Ce3+ values of zircon in the quartz monzonite porphyry vary from 204.5 to 886.5, indicating that the intrusion might have formed in an environment with high oxygen fugacity. Additionally, the quartz monzonite porphyry exhibits high contents of Al2O3, Sr, Ba, and Mg# (Mg# = Mg2+/(Mg2+ + Fe2+)) and low ratios of Y, Nb, Ta, and K2O/Na2O, showing geochemical characteristics similar to those of adakitic rocks. Based on these characteristics, it is suggested that the intrusion might have been derived from the partial melting of subducted oceanic crust under a continental arc margin setting. Furthermore, it is strongly indicated that the quartz monzonite porphyry from the Shanlixu deposit, in the Lujiang–Chuzhou Area, is closely related to Cu-Au mineralization, as suggested by the age of the intrusion, which is approximately 137 Ma. These findings provide a new direction for research and exploration in this region.

The South China Plate is an important part of the Rodinia supercontinent in the Neoproterozoic. The Rizhao area, located on the northeastern margin of the South China Plate, records multiple periods of magmatism, among which Neoproterozoic granitic gneiss is of great significance to the tectonic evolution of the South China Block. In this study, systematic petrology, geochemistry, isotopic chronology, and zircon Hf isotopic analyses were carried out on gneisses samples of biotite alkali feldspar granitic and biotite monzogranitic compositions in the Rizhao area. Geochemical analyses suggest that these granitic rocks belong to the sub-alkaline series and have high potassium contents. They are enriched in large-ion lithophile elements K, Rb, and Ba; depleted in high field strength elements P, Nb, and Ti; enriched in light rare earth elements and moderately depleted in heavy rare earth elements; and have weak to moderate negative Eu anomalies and weak negative Ce anomalies. These rocks are post-orogenic A-type granites. LA-MC-ICP-MS U-Pb dating of zircons from two biotite alkali-feldspar granitic gneiss samples yielded weighted mean ages of 785 ± 8 Ma (MSWD = 3.0) and 784 ± 6Ma (MSWD = 1.5), respectively, and a biotite monzogranitic gneiss sample yielded a weighted mean age of 789 ± 6 Ma (MSWD = 2.3). Lu-Hf isotopic analyses on zircon grains from the two types of Neoproterozoic-aged gneisses yielded negative εHf(t) values ranging from −19.3 to −8.8 and from −18.3 to −10.4, respectively, and the corresponding two-stage Hf model age ranges are 2848–3776 Ma and 2983–3682 Ma, respectively. These granites are the product of Neoproterozoic magmatic activity and are mainly derived from the partial melting of Archean continental crust. Combining the geochemical characteristics and zircon U-Pb-Lu-Hf isotopic analyses, these A-type granitic gneisses appear to have formed in an intracontinental rift extension environment during the initial break-up of the Rodinia supercontinent, as part of the supercontinent break-up process at the northeastern margin of the South China Block.

Late Carboniferous–Early Permian granitoids are widespread in the Tianshan area and their tectonic setting is controversially discussed. Our research presents fresh whole-rock geochemical and Pb isotopic data, along with zircon U-Pb ages and Hf isotopic data for representative monzonitic and granitic intrusions in the Kumishi area. The aim is to decipher their magma sources and illuminate their geodynamic evolution. Zircon U-Pb dating results reveal that biotite monzonites in the Central Tianshan Belt were emplaced at 312.7 ± 2.9 Ma, while the quartz-monzonites and syenogranites in the South Tianshan Belt were formed at 284.5 ± 2.4 Ma and 283.4 ± 3.9 Ma, respectively. The biotite monzonites generally exhibit metaluminous and high-K calc-alkaline characteristics. They have a positive εHf(t) value (+4.9–+14.1), and are enriched in LREEs and LILEs but depleted in HREEs and HFSEs. These characteristics indicate that they were derived from a mixed magma source of the lower crust and the input of components derived from the mantle wedge above the subduction zone. The quartz-monzonites and syenogranites are high-K calc-alkaline to shoshonitic I-type granites, with εHf(t) values of +14.9–+15.5 and +6.6–+14.9, respectively. They are enriched in LREEs but depleted in HFSEs (e.g., Nb, Ta, and Ti), displaying relatively flat HREE patterns and negative Eu anomalies. The genesis of these rocks is attributed to a partial melting of the lower crust in which mantle-derived magmas participated, which was triggered by an upwelling asthenosphere in a post-collisional extensional geodynamic setting. These granitoids, together with regional analysis of other magmatism in the study area, suggest that the Kumishi area has experienced an evolution from subduction to post-collision from the Late Carboniferous to the Early Permian, which constrains the local closure of the Paleo-Asian Ocean.

Although considered a crucial component of the Rodinia supercontinent, it remains uncertain how the Yangtze craton relates to the accretion and breakup of Rodinia. Here, the Huanglingmiao granitic complex (HGC), an intermediate-acid rock series that intruded on the southern Kongling terrane of the northern Yangtze craton margin, is investigated to help resolve this conundrum. Our analysis indicates that these rocks consist of tonalite, trondhjemite, granodiorite, oligoporphyritic granodiorite, porphyric biotite granodiorite, and fine- to medium-grained granodiorite dyke compositions. Collectively, this assemblage is further subdivided into two categories by their temporal, spatial, and geochemical features into early TTG-like and later granitic–dioritic units, which are composed of tonalite, trondhjemite, granodiorite, porphyritic granodiorite, and the fine- to medium-grained granodiorite dykes, respectively. Zircon U-Pb dating yields ages of 865~850 Ma for the TTG-like rocks, 844~825 Ma for the porphyritic granodiorites, and ~800 Ma for the granodiorite dykes. Combined with geochemical evidence, the data suggest that the early- and late-series rocks were formed by a partial melting of Mesoproterozoic and Paleoproterozoic crustal materials, respectively, suggesting that the vertical layering of the crust controlled the composition of the independent units. In addition, isotopic evidence points to different sources for the various rocks in the Kongling terrane and that mantle-derived materials influenced the early-series lithologies. Combined with previous studies on the northern margin of the Yangtze craton, it is inferred that the early-series rocks formed in an active continental margin environment, while the late-series rocks display within-plate boundary formation characteristics. The multiple magmatic activities revealed by this study record sequential partial melting with tectonic transition characteristics from an Andean-type to within-plate magmatism in the northern margin of the Yangtze craton. Taken together, these observations point to a strong association between these rocks, convergence, and incorporation of the northern Yangtze craton margin into the Rodinia supercontinent during the Tonian Period.