Abstract:

Post-collisional Cu-Au-Ni-Co-Pt-Pd-Sc porphyry, [Duck Creek porphyry system (DCPS)], with overlying Au-Te-Bi-W-HRE epithermal mineralisation, [Highway epithermal system (HES)] has been discovered in the core of the Mitakoodi anticline, southwest of Cloncurry. Xenotime and monazite geochronology indicates mineralisation occurred between ~1490 and 1530 Ma. Host rock lithologies show widespread potassic and/or propylitic to phyllic alteration. Paragenesis of porphyry sulphides indicate early crystallisation of pyrite, followed by chalcopyrite, with bornite forming by hydrothermal alteration chalcopyrite. Cu sulphides also show the effect of supergene oxidation alteration with rims of covellite, digenite and chalcocite. Redox conditions deduced from V/Sc systematics indicate that the DCPS contains both highly oxidized (typical of porphyries) and reduced lithologies, typical of plume generated tholeiitic and alkaline suites. Ni/Te and Cu/Te systematics plot within the fields defined by epithermal and porphyry deposits. Duck Creek chalcophile and highly siderophile element (Cu, MgO and Pd) systematics resemble data from porphyry mineral systems, at Cadia, Bingham Canyon, Grasberg, Skouries, Kalmakyr, Elaisite, Assarel and Medet. SAM geophysical inversion models suggest the presence of an extensive porphyry system below the HES. A progressive increase in molar Cu/Au ratios with depth from the HES to the DCPS, supports this conclusion. Three metal sources contributed to the DCPS-HES viz., tholeiitic ferrogabbro, potassic ultramafic to mafic system and a Fe and Ca-rich alkaline system. The latter two imparted non-crustal superchondritic Nb/Ta ratios that are characteristic of many deposits in the eastern Mount Isa Block. The associated tholeiite and alkaline magmatism reflect mantle plume upwelling through a palaeo-slab window that had accreted below the eastern flank of the North Australian craton following west verging collision by the Numil Terrane. Discovery of this linked mineral system provides a new paradigm for mineral exploration in the region.

Abstract: Papua New Guinea is one of the least studied regions in the Southwest Pacific, and large areas of the country, such as the Fly Plat-form, remain poorly understood due to limited exposure and access constraints. This study presents the first documentation of basaltic volcanism on the Fly Platform, based on new field discoveries at Mea-hill and Yemsigi, two areas located approximately 25 km apart. Inte-grated field observations, petrography, mineral chemistry, and whole-rock geochemistry show that both basalt suites were derived from a similar magma source but record contrasting emplacement histories. Meahill basalts, which include welded tuffs and highly ve-sicular basalt units, reflect rapid magma ascent, vigorous degassing, and locally explosive activity. In contrast, the massive, less vesicular porphyritic basalts at Yemsigi preserve a quieter emplacement history, but with more extensive post-magmatic alteration. Geochemical sig-natures from least altered rocks of both suites support an intraplate origin with similarities to Pliocene-Pleistocene lava fields of Northeast Queensland. The origin of the intra-plate basaltic magmatism is enig-matic, but both young volcanic provinces correlate spatially with a lower mantle anomaly that may represent residual slab material and a seated-seated magma source. These findings provide further insight into the tectono-magmatic evolution of the Fly Platform region and highlight the need for continued geological investigation in this underexplored district.

Abstract: ligocene rocks and fluids of A-1X well were conducted for source rock and fluid characterization and implying the suitable geological sites for CO2 storage from high-salinity water in sandstone reservoirs based on Rock-Eval pyrolysis, vitrinite reflectance measurement, bitumen extraction, hydrocarbon fractionation, gas chromatography, stable carbon isotope, formation water and X-Ray Diffraction analyses. Shale source rocks reveal fairly good potential of hydrocarbon generation. Compositions of gas sample in gas-related zones 1010-1110m are mainly composed of CH4, following C2+, N2, and a little content of CO2 and no noticeable of H2S. Carbon isotopes of oil and gas samples reveal the organic matters mainly derived from sapropelic and little humic sources, entering the mature stage to oil window phases. The formation water is classified as Calcium-Chloride type that contain high concentrations of total dissolved solid, salinity, and K+, Na+ and Cl- cations. This formation water is associated with deep source, and close system that are effective conditions for a large pool with good sealing capacity and not impacted by dissolution of the salt rock around. Most sandstones comprise very high visual porosities including high quartz, plagioclase and calcite minerals that are favorable conditions for subsurface pore space and CO2 injection in over saturated fluids. The popular presence of brittle minerals in the upper part of strongly fractured basement indicates this could be a good sandstone reservoir. The finding is identification of suitable candidate for storing CO2 in the saline aquifer under the active petroleum system with current oil and gas accumulations.

Abstract: The Wailukum area in North Maluku Province, Indonesia, is an ultramafic rock com-plex with a high degree of serpentinization. The mineral composition of ultramafic and mafic rocks strongly influences scandium (Sc) distribution and enrichment during lat-eritization. This study aims to analyze the element distribution, mineral composition, and rock identification in three types of geological materials in a lateritic profile which contains Sc, specifically bedrock, saprolite, and limonite. The analytical methods used are petrography, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Inductively Cou-pled Plasma (ICP), and Scanning Electron Microscopy – Energy Dispersive Spectros-copy (SEM-EDS). Results show that in the bedrock, Sc is mainly hosted in clinopyrox-ene minerals such as augite and diopside, with minor amounts in chromite, magnetite, dolomite, and anorthite. In the saprolite, Sc content decreases due to higher mobility but remains partly associated with clinopyroxene and chromite. In the limonite zone, Sc reaches maximum enrichment, primarily hosted in Fe–Mn oxides including goe-thite, magnetite, and asbolane. Among rock types, gabbro contains the highest abso-lute Sc concentration (23.25 ppm in bedrock and up to 58.5 ppm in limonite), while wehrlite records the greatest enrichment ratio, with a 9.18-fold increase from bedrock to limonite. In contrast, gabbro shows the lowest enrichment ratio (2.52-fold) despite its high initial Sc content. These patterns indicate that Sc enrichment is controlled by clinopyroxene as the primary host in bedrock, its relative stability during weathering, and the subsequent fixation of Sc in Fe, Cr, and Mn oxides within the lateritization profile.

Abstract: Geochemical, petrographic, and geochronological analyses of granitoids from Kan-chanaburi Province, western Thailand, reveal key insights into magmatic evolution and metallogenesis within the Western Granite Belt. U–Pb zircon dating identifies two main magmatic episodes: Late Triassic (227-214 Ma), and Late Cretaceous (79-68 Ma). The granitoids, including quartz monzonite, granodiorite, and quartz-rich gran-ite, are composed of quartz, plagioclase, K-feldspar, and biotite, with minor horn-blende and accessory minerals such as titanite, zircon, magnetite, ilmenite, and garnet. Magnetic susceptibility values (0.0001 × 10-3 to 0.0199 × 10-3 SI units) indicate pre-dominantly ilmenite-series granitoids, with localized magnetite-series occurrences. Geochemical data classify these intermediate to felsic plutonic rocks as calc-alkaline to shoshonitic, with a peraluminous, S-type affinity. U-Pb cassiterite and wolframite ages of 80-77 Ma suggest that W-Sn mineralization occurred during the Late Cretaceous at early-stage magmatism. The temporal and spatial distribution of these granitoids is closely linked to Pb–Zn–W–Sn mineralization, reflecting the influence of post-collisional magmatism on regional metallogenesis in the Sibumasu Terrane. This study refines the tectono-magmatic framework of western Thailand and underscores the importance of granitoid emplacement timing in controlling mineral deposit for-mation.

Abstract:

Water quality assessment is crucial for the sustainable use and management of groundwater resources. This study was carried out in the irrigated plains of Vehari District, Punjab, Pakistan, to evaluate groundwater suitability for a managed aquifer recharge (MAR) project. Twenty-three groundwater samples were collected in June 2021 from an area of 1,522 km² and analyzed for major physicochemical parameters including electrical conductivity (EC), total dissolved solids (TDS), pH, turbidity, calcium (Ca), magnesium (Mg), chloride (Cl), alkalinity (Alk), bicarbonate (HCO₃⁻), hardness, potassium (K), sulphate (SO₄²⁻), sodium (Na), and nitrate (NO₃⁻). Water quality was assessed using WHO and PID standards, alongside derived hydrochemical indices such as sodium percentage (%Na), Kelley’s ratio (KR), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and the water quality index (WQI). The dataset was interpreted using geo-statistical, geospatial, multivariate, and correlation analyses. Cation and anion dominance followed the order Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > SO₄²⁻ > Cl⁻ > NO₃⁻. WQI results showed that 35% of samples indicate “poor,” 50% “very poor,” and 15% “unsuitable” drinking-water quality. However, irrigation suitability indices confirmed that groundwater is generally acceptable for agricultural use, though unfit for drinking. The outcomes of this study provide essential insights for groundwater management in the region, where the Punjab Irrigation Department (PID) has initiated a MAR project. Considering that the irrigation sector is the major groundwater consumer in the area, the compatibility of groundwater and surface water quality supports the implementation of MAR to enhance agricultural sustainability.

Abstract: Detailed geochemical modelling of the potential groundwater impacts of CO2 geo-sequestration requires site-specific knowledge of how mobile elements are hosted within rocks. We present a simple sequential extraction procedure analogous to pH conditions produced by different partial pressures of carbon dioxide (CO2) in contact with water. The procedure consists of three sequential steps: Water at pH 7; acetic acid–ammonium acetate at pH 5 and then at pH 3, with the amounts of specific elements extracted by each step considered with respect to whole-rock total element abundance. Our purpose in developing this procedure is three-fold: 1) identify readily mobilised suites of elements for groundwater baseline and monitor bore studies; 2) provide insights regarding the mode/s of occurrence of easily extracted elements within rock samples; and 3) suggest possible mechanisms for the mobilisation of rock-sourced elements into groundwater under neutral to moderately acidic pH that can inform reactive transport modelling of carbon storage sites. In our case study, the second step extracted most of the main mobile elements of interest.

Abstract: Birnessite is a layered manganese oxide with strong oxidizing ability, but the electronic reason for this property is still unclear. In this work, eight birnessite samples with different interlayer cations and Mn(III)/Mn(IV) ratios were studied to explore how electron affinity (EA) affects oxidation behavior. The samples were examined by XRD, XPS, SEM and UPS, and oxidation tests were carried out with Fe(II) and phenol under controlled pH and temperature. The electron affinity values ranged from 5.52 to 5.93 eV, increasing from Na⁺- to K⁺-, Ca²⁺- and Mg²⁺-birnessite. Samples with higher EA showed faster oxidation, and the Fe(II) removal rate was about 2.1 times higher than that of low-EA samples. The relationship between EA and rate constant followed an exponential trend (R² = 0.96). Surface and spectral data showed that samples with higher EA had slower Mn(IV) loss and later surface passivation. These results show that electron affinity controls the oxidizing ability of birnessite and can be used to predict and improve the performance of manganese oxides in pollutant removal and catalytic oxidation.

Abstract: We have investigated the major- and trace-element composition of hydrothermal pyrite, magnetite, and titanomagnetite, and of the principal Cu-minerals chalcopy-rite and chalcocite, to constrain ore-forming processes in the northeastern Saveh district (central Urumieh–Dokhtar magmatic arc, Iran). Our data provide new con-straints on the magmatic–hydrothermal evolution and subsequent hydrothermal–supergene modification of the ore system. Titanomagnetites hosted in shallow monzo-dioritic intrusions are enriched in Ti–V–Al, plot below the magnetite–ulvöspinel join and record high crystallization temperatures (< ~500 °C) under rela-tively low oxygen fugacity. By contrast, magnetites from silica-rich hydrothermal veins are relatively Fe-rich, have very low TiO₂, formed at intermediate tempera-tures (~200–300 °C) under higher fO₂, and show pronounced depletion in Ti and V relative to monzo-dioritic oxides. Textures and oxide systematics (Al+Mn vs Ti+V; V/Ti–Fe) document repeated hydrothermal pulses, Fe²⁺ leaching and element redis-tribution during cooling and fluid–rock interaction. Geochemical trends indicate progressive evolution from a magmatic fluid to later meteoric water overprint, with decreasing As contents reflecting mixing with oxidizing meteoric waters. Vertical elemental zoning suggests that most samples represent mid- to deep-level sections of the epithermal system. Elevated Cu contents (up to 0.95 wt.%) highlight pyrite as a significant Cu host. Co/Ni ratios between 1 and 10 further corroborate a magmatic–hydrothermal origin. Chalcopyrite is the principal economic Cu carrier at Northeast Saveh. Replacement follows a temperature- and fluid-controlled pathway (chalco-pyrite → covellite → chalcocite/digenite). At lower temperatures (< ~200 °C) re-placement proceeds more slowly, producing chalcocite/digenite under prolonged reaction conditions. Chalcocite commonly occurs as thin replacement rims and fracture fills that concentrate remobilized copper. Collectively, the investigated oxide and sulfide proxies provide robust discriminants for separating magmatic versus hydrothermal domains and for vectoring toward higher-temperature feeders and zones of remobilized copper.

Abstract: The magmatic activity is crucial for identify the tectonic framework of ancient ocean. In this study, a systematically work including field survey, zircon LA-ICP-MS U-Pb dating, and whole-rock geochemical analysis is carried on to investigated the intrusive magmatic rocks of quartz diorite and granodiorite within the Meso-Tethyan Shiquanhe Ophiolitic Mélange (SQM), Tibet. Zircon U-Pb dating yields the weighted mean ages of 174.7±1.4 Ma (quartz diorite) and 178.9±1.2 Ma (granodiorite) respectively, indicating the Early Jurassic formation age. The quartz diorite is metaluminous (A/NKC = 0.77-0.95), while the granodiorite is weakly peraluminous (A/NKC = 0.95-1.21), and both of them exhibit tholeiitic–calc-alkaline geochemical characteristics and classified as I-type granites. The right-dipping rare earth element (REE) patterns, enrichment in large ion lithophile elements (LILEs: Rb, Ba, Th), and depletion in high field strength elements (HFSEs: Nb, Ta, Ti), as well as relatively high (La/Yb)N ratios represent the is-land arc TTG-like magmatism origin. Combine with the previous works, we suggest the Shiquanhe opiolitic mélange represent an island arc and back-arc assemblage rather than an independent ocean basin. Meanwhile, this Early Jurassic island arc magmatism initiated a new era of the Mesozoic mineralization in Shiquanhe area.

Abstract:

Understanding how processes of magma genesis and magma differentiation control and modify the chemical composition of erupted lavas from the geochemical measurements of the latter is an under-constrained inverse problem as there is only one known parameter – the measured composition of the erupted lava – but two unknown parameters – the chemical composition and lithology of the source before melting and how melting, crystallization, and melt-rock interactions act to alter the lava en route to the surface. In this invited contribution, we review nearly seven decades of scientific research that demonstrate the potential of U and Th decay series measurements for unraveling the complexities of oceanic magmatism. We review the underlying nuclear theory, geochemical principles, and application of the ²³⁸U, ²³⁵U, and ²³²Th decay series for (i) defining the timescales of magma genesis during decompression mantle melting, (ii) establishing the timescales of magma recharge and magma degassing, and (iii) determining the eruption ages of oceanic Quaternary volcanism.

Abstract:

Pt-Fe alloys with abundant inclusions from the Camumbi River placer deposit, Ecuador, are derived from unknown Alaskan-Uralian type intrusion(s) within the Late Cretaceous Naranjal accreted terrane. Our previously documented silicate inclusions are increasingly fractionated from hydrous ferrobasalt to rhyolite in terms of TAS (total alkalis vs. silica). Liquid lines of descent change from tholeiitic to the calc-alkaline magma series. Here, we document seven exceptional composite inclusion parageneses of Cu–PGM (platinum-group mineral) sulfides, each exsolved from coexisting, fractionated silicate glass (melt). Differentiation is dominated by fractional crystallization in PGM bulk compositions from tholeiitic silicate melts at highest T ~1018 °C. Silicate inclusions following the lower T calc-alkaline trend coexist with sulfide PGMs likely differentiated (in terms of Pt-Rh-Pd and BMs, base metals) by incongruent melting due to decompression and S-degassing at ~983–830 °C. S-saturated sulfide melts become S-undersaturated below 845 °C. Calculated Ts are for silicate glass. Pt-rich braggite shows increasing fractionation towards Pd-rich vysotskite within one inclusion paragenesis. A late braggite–vysotskite trend is towards decreasing minor BMs. Thiospinels are dominated by cuprorhodsite. Minor thiospinels indicate Fe- then strong Ni-enrichment at lowest Ts. Decompression exsolutions, deflation and partial melting of some sulfide inclusion parageneses support rapid ascent to higher crustal levels within a deep-sourced cumulate intrusion.

Abstract: Synthesis of published and new data from Govorov and Kocebu guyots provides geochemical and chronostratigraphic constraints on hydrogenetic cobalt-rich Fe-Mn crusts from the Western Pacific Magellan Seamount Trail (MST). The history of the crusts began about 65–60 Myr ago, when the relict layer R was deposited in the Campanian–Maastrichtian and Late Paleocene along the shores of guyots. The growth of the old-generation crusts continued in the Late Paleocene–Early Eocene (Layer I-1) and in the Middle–Late Eocene (Layer I-2) in a shallow-water shelf environment. The younger layers of crusts formed in the Late Oligocene–Early Miocene (Layer I-2b), Miocene (Layer II), and Pliocene–Pleistocene (Layer III) at depths about the present sealevel. The precipitation of Fe and Mn oxyhydroxides from seawater was interrupted by several episodes of dissolution, the longest one between the old and young layers of Fe-Mn crusts (from 38 to 26.5 Ma). Fe and Mn oxyhydroxides in the crusts were affected by two global events of phosphogenesis in the Pacific: Late Eocene–Early Oligocene, from 43 to 39 Ma (Layers R, I-1, I-2) and Late Oligocene–Early Miocene, from 27 to 21 Ma (Layer I-2b). The trace element patterns in different layers of the Fe-Mn crusts are grouped using factor analysis of principal components (varimax raw) into four factors: (1) + (all REEs except Ce and La); (2) +(Ce, La, Ba, Mo, Sr, Pb); (3) +(Zr, Hf, Nb, Rb, As)/-Pb; (4) +(U, Th, Co, As, Sb, W)/-Y. The factor score diagrams highlight fields which are especially contrasting for Layers I-1, I-2 and II+III according to factors 2 and 4. Consistent REE and Y variations in Layers I-2b→II →III of the crust from Pallada Guyot correlate with gradual ocean deepening between the Late Oligocene–Early Miocene and Present when the MST guyots were submerging. Large variations in trace element contents across coeval layers may be due to hydrodynamics of currents on the guyot surfaces. Furthermore, the geochemistry of the crusts bears effects from repeated episodes of Cenozoic volcanism in the MST region of the Pacific Plate. Higher contents of Nb, Zr, As, Sb, and W in the younger layers II and III may result from large-scale volcanism, including Miocene eruptions of petit-spot volcanoes.

Abstract:

The origin of Mesozoic granites associated with the Dahutang W-Cu-Mo orefield in north Jiangxi, which host the world’s second largest tungsten deposit, remains a compelling subject despite extensive geochemical and geochronological studies. In this contribution we present new wolframite mineral and bulk-rock geochemistry and monazite U-Pb ages for the Mesozoic granites in aiming to enhance our understanding the petrogenesis of these granites and its coupling relationship with the mineralization. Two magmatic phases and four types of rocks in study area are identified, i.e., the early stage (152-147 Ma) biotite (G1) granite and the late stage (144-130 Ma) two-mica (G2)＋muscovite (G3)＋albite (G4) granite series. These two magmatic phases are temporally coincident with two mineralization stages (~150 Ma and 139-144 Ma). All the Mesozoic granites share the characteristics of high silica content, peraluminosity (A/CNK > 1.1), and low Zr+Nb+Ce+Y values (< 200 ppm), and they are derived from the partial melting of a Proterozoic crustal source. Specifically, the G1 granite, characterized by relatively high MgO (~0.5%), CaO (~1%), and low P₂O₅(0.13%-0.20%), is classified as an I-type granite. It formed via a relatively higher degree of partial melting at ~766°C (Zr saturation temperatures) driven by biotite breakdown reactions, with minor contributions from mantle-derived materials. In contrast, the G2–G4 granites series exhibits typical peraluminous S-type granite features, such as high Al₂O₃, Na₂O, and P₂O₅ (mostly >0.2%) contents, and low Sr and Ba contents. They are products of low-degree partial melting that occurred under conditions close to muscovite breakdown at ~735°C. Additionally, both granites show clear geochemical evidence of fluid interaction, as reflected by their elevated trace element and volatile contents: Sn>30 ppm, Cs >35 ppm, F >0.4%, Li >250 ppm, W 10–1000 ppm, Rb >500 ppm, K/Rb values <150, and Nb/Ta<5. The G1 granite represents a moderately fractionated melt relative to chondrites, as evidenced by its near-chondritic Zr/Hf (22.6-34.1) and Y/Ho (24.5-31.5) ratios, indicating a weaker influence of magmatic fluid-melt interaction. For the G2-G4 granites, however, intense crystal fractionation and late-stage fluid-melt interaction are well-documented by their highly variable and low ratios of Y/Ho (14.8-41.4), Nb/Ta (0.89-5.57), Zr/Hf (8.84-41.67), and K/Rb (13.96-128.29). In the long-lived, reduced, and volatile-rich aqueous environment of the G2–G4 magmas, fractional crystallization and albitization collectively enhanced the solubility and hydrothermal transport capacity of W, Sn, Li, Nb, and Ta by multiple orders of magnitude. In contrast, in the earlier, more oxidized G1 magma (which incorporated mantle materials), the exsolution and hydrothermal transport of Cu and Mo were associated with localized greisenization, but their capacity diminished with fractional crystallization. Historically, mineral exploration in the Dalutang mining area has focused primarily on W, Cu, and Mo. Based on this research, we conclude that there is significant mineral potential for rare metals (particularly Sn, Li, and Ta), and future surveys should prioritize areas adjacent to the evolved G2–G4 peraluminous leucogranites to search for new concealed mineral occurrences.

Abstract: Zibai Jade is a recently identified hydrogrossular-dominant jade originating from Shaanxi Province, China. It constitutes a polymineralic aggregate composed predominantly of hydrogrossular, with minor proportions of vesuvianite, diopside, chlorite, uvarovite, and calcite. A multi-method analytical approach was employed to characterize the jade, incorporating conventional gemological testing, polarizing microscopy, SEM, XRD, BSE, XRF, EPMA, as well as UV-Vis, infrared IR. These techniques enabled a detailed examination of its mineralogy, surface features, and color origin. The stone displays heterogeneous color distribution, featuring a base hue of light green to yellowish-green, accompanied by distinct occurrences of emerald-green spots, dark green spots, mossy green inclusions, white patches, white veinlets, and black dot with a green ring.Microanalytical results indicate that the emerald-green spots are principally composed of uvarovite. The dark green sports are dominated by hydrogrossular, diopside, and chlorite. Fibrous green inclusions consist mainly of chlorite and Cr-bearing grossular. White patches and veinlets are primarily composed of calcite. The black dot with a green ring are predominantly comprised of chromite and uvarovite.Coloration is attributed to the combined influence of Fe and Cr3+. The formation of the jade involved three mineralization stages: protolith accumulation, high-temperature metasomatism, and retrograde alteration. The interplay of these processes resulted in the development of Zibai Jade, which exhibits a dense texture and attractive coloration.

Abstract: The He 1 Member of the Xiashihezi Formation (Upper Paleozoic) in the Ordos Basin represents typical tight sandstones. However, against the extensive tight sandstone background of the He 1 Member in the southern basin, conventional reservoirs (Φ>12%, K>1 mD) occur locally. Elucidating the genetic mechanism of these conventional reservoirs is critical for evaluating gas reservoirs in this region. Based on core descriptions and systematic sampling from cored wells, reservoir types are classified according to pore types and porosity in sandstones. Depositional microfacies, petrology, and diagenesis of each reservoir type are then investigated to ultimately elucidate the genetic mechanism of conventional reservoirs. Results demonstrate that intense compaction and quartz overgrowths are the primary controls on the development of the He 1 Member tight sandstones. Alteration of volcanic lithic fragments and volcanic ash matrix generated abundant intragranular dissolution pores and micropores within matrix, while simultaneously producing substantial illite-smectite mixed-layer clays and chlorite clays. Additionally, this process supplied silica for quartz overgrowths. Moderate amounts of chlorite coatings can inhibit quartz overgrowths, thereby preserving residual intergranular porosity. Conventional reservoirs exhibit low lithic fragment content and coexisting intergranular and intragranular dissolution porosity. Their formation requires weak compaction, intense dissolution, and weak quartz overgrowths. These reservoirs develop within high-energy transverse bars that are sealed by overlying and underlying mudstones. Such transverse bars constitute closed intrastratial-diagenetic systems with restricted mass transfer during burial. This study provides a compelling example of diagenetic heterogeneity induced by variations in sandstone architecture within fluvial successions.

Abstract: This study presents the application of Mycelial_Net, a biologically inspired deep learning architecture, to the analysis and classification of mineral images in thin section under optical microscopy. The model, inspired by the adaptive connectivity of fungal mycelium networks, was trained on a test mineral image database to extract structural features and to classify various minerals. The performance of Mycelial_Net was evaluated in terms of accuracy, robustness, and adaptability, and compared against conventional convolutional neural networks. The results demonstrate that Mycelial_Net, properly integrated with Residual Networks (ResNets), offers superior analysis capabilities, interpretability, and resilience to noise and artifacts in petrographic images. This approach holds promise for advancing automated mineral identification and geological analysis through adaptive AI systems.

Abstract: Marine deposits in Western Europe provide insight into the interplay between the warm Tethys and cooler Boreal domains, offering a climatic context for the radiation of Early Jurassic species. Reconstructions of temperature for the Hettangian and Sinemurian periods are scarce, with inferred marine temperatures of 15–20°C based on δ18O values, which are lower than those of subsequent Jurassic stages. This emphasises the necessity for supplementary data in order to enhance our comprehension of the climatic dynamics that characterised the Early Jurassic period. This study analyses 75 invertebrate samples, including 53 specimens of Gryphaea arcuata, from Early Sinemurian marine sediments in the Fresville quarry, Normandy, France. The present study employs a multi-proxy approach, utilising δ13C and δ18O values in conjunction with Sr and Mg contents, to assess the processes of fossil diagenesis, marine productivity and seawater temperatures. Significant post-depositional alteration was observed in the geochemical compositions of 22 bivalve shells assigned to the genera Pseudolimea, Plagiostoma and Chlamys, which were originally composed of aragonite. However, the low-Mg calcite shells of Gryphaea arcuata, which are renowned for their diagenetic resistance, retained the majority of their isotopic integrity. The results of the statistical analyses indicate that there was minimal late pervasive diagenesis involving meteoric waters at Fresville. This is in accordance with the typical decrease in δ13C, δ18O values and Sr and Mg contents that such processes would otherwise cause. Published isotopic data from Sinemurian marine fossils (plesiosaur and shark teeth) were used to estimate seawater δ18O (~ -1‰ VSMOW or -1.27‰ VPDB) and surface temperatures (~24°C). The calculated benthic temperatures of Gryphaea (17°C) correspond to habitats at depths of about 50 m. These findings suggest a positive hydrological balance, euhaline conditions, and elevated marine productivity in a humid tropical climate context.

Abstract: This study investigates the Terrigenous-carbonate Sakar-type Triassic (TCSTT) and Sakar-type Triassic (STT) metasedimentary successions in the Sakar Unit, SE Bulgaria. Both share lithological similarities (alternation of carbonate-silicate schists, mica schists, marbles, and impure marbles) and are affected by post-Triassic metamorphism, but exhibit differences in metamorphic grade and provenance. The STT displays a higher metamorphic grade (low amphibolite facies) compared to the TCSTT (low greenschist facies). Petrographic observations and geochemical analyses indicate protoliths composed of arkosic sandstones, shales, and limestones, derived from a quartz-dominated source with minor contributions from intermediate magmatic sources. U-Pb geochronology of detrital zircons reveals a dominant Carboniferous age, supplemented by early Ordovician ages, consistent with the presence of Carboniferous-Permian magmatic rocks in the basement. The presence of Early Paleozoic and Cambrian-Neoproterozoic zircons in the detrital zircon populations suggests that older rocks in the basement of the Sakar Unit and Srednogorie zone are also sources of the sedimentary material. Based on immobile trace elements contents and discrimination diagrams, the siliciclastic component comes from rocks formed in a continental arc tectonic setting. REE patterns exhibit a negative Eu anomaly, inherited from the granitic source rocks.

Abstract: Underground hydrogen storage (UHS) in carbonate and siliceous formations presents a promising solution for managing intermittent renewable energy. However, experimental data on hydrogen-rock interactions under representative subsurface conditions remains limited. This study systematically investigates mineralogical and petrophysical altera-tions in dolomite, calcite-rich limestone, and quartz-dominant siliceous cores subjected to high-pressure hydrogen (100 bar, 70°C, 100 days). Distinct from prior research focused on diffraction peak shifts, our analysis prioritizes quantitative changes in mineral concentra-tion (%) as a direct metric of reactivity and structural integrity, offering more robust in-sights into long-term storage viability. Hydrogen exposure induced significant dolomite dissolution, evidenced by reduced crys-talline content (from 12.20% to 10.53%) and accessory phase loss, indicative of partial de-carbonation and ankerite-like formation via cation exchange. Conversely, limestone ex-hibited more pronounced carbonate reduction (vaterite from 6.05% to 4.82% and calcite from 2.35% to 0%), signaling high reactivity, mineral instability, and potential pore clog-ging from secondary precipitation. In contrast, quartz-rich cores demonstrated exceptional chemical inertness, maintaining consistent mineral concentrations. Furthermore, BET and BJH analyses revealed enhanced porosity and permeability in do-lomite (pore volume increased >10x), while calcite showed declining properties and quartz negligible changes. SEM-EDS supported these trends, detailing Fe migration and textural evolution in dolomite, microfissuring in calcite, and structural preservation in quartz. This research establishes a unique experimental framework for understanding hydrogen–rock interactions under reservoir-relevant conditions. It provides crucial insights into mineralogical compatibility and structural resilience for UHS, identifying dolomite as a highly promising host and highlighting calcitic rocks limitations for long-term hydrogen containment.