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The MOS model (acronym coming from the French MOdèle Simplifié) was born from the desire to have a simple tool that can quantify the contribution of the diffusive reactive environment to the alteration of a vitrified nuclear waste package in deep geological disposal conditions. In the model, this environmental contribution consists partly of the ability of iron, metallic casing corrosion products, and argillite to consume silicon, and partly of the brake on diffusive transport provided by silicon through the successive layers of environmental material. It is a modeling tool serving as an intermediary between operational modeling for the calculation of the source term from the glass, mathematically more simple and giving higher upper margins, and models that use geochemistry and transport, giving greater accuracy for the interactions between glass and its environment. The goal of the MOS model is to calculate the possible impact of silicon reactive diffusion on the alteration rate within the different layers of material surrounding nuclear glass. This article lists the simplifying hypotheses on which the MOS is based, presents the digital resolution method for an environment consisting of several successive layers with different reactivity and transport properties, and explains the model's implementation. [ABSTRACT FROM AUTHOR]

In this study, laser ablation–multicollector–inductively coupled plasma–mass spectrometry (LA–MC–ICP–MS) of apatites and LA–ICP–MS of zircons are used to collect U–Pb geochronological data, Rb–Sr isotope chronology is used to analyze alkaline feldspar and plagioclase, and archival apatite geochemistry data for the exposed Naitoushan basalt and Heishigou dike in the Changbaishan Tianchi volcano (CTV) are accessed to examine the petrogenesis and determine the origin of basaltic magmatism in the CTV. The Naitoushan basalt and Heishigou dike formed at 22.2–18.7 and 0.230–0.218 Ma, respectively. In situ oxides, volatiles, trace element geochemistry and Sr–Nd isotopes of apatite are reported for two samples. Most apatites are in the early crystallization phase and form inclusions in plagioclase that are euhedral or subhedral. They have higher MgO and K2O/Na2O concentrations; lower F and Cl concentrations; Ba, Sr, Nb, Ta, Zr, Hf, K, and Ti depletion; and Th, U, Ce, Pb, P, and Nd enrichment. All apatite samples are enriched in light rare earth elements (REEs) relative to heavy REEs and have relatively homogeneous Th/U, Zr/Hf, La/Sm, and Nd/Tb ratios and Sr–Nd isotopic compositions; thus, their host magmas potentially have the same magmatic origin as oceanic island basalt. The apatite La, Yb, and U contents, Eu/Eu* and La/Yb values, and high REE contents show a weak crystallization sequence in the mafic magma. This study demonstrates that the pre-shield and post-shield mafic magmas in the CTV were likely derived from an enriched mantle source with an I-type signature related to the rollback of the Pacific plate. [ABSTRACT FROM AUTHOR]

The content and distribution of precious metals in fine-grained bottom sediments, accumulated in the technogenic period (last decades) in the southwestern part of the Chukchi Sea, have been studied. The ubiquitous or local enrichment of the sediments with silver, gold, platinum, and palladium according to the average for the Earth's crust, as well as their enrichment with gold and palladium relative to pre-technogenic (Late Holocene) deposits, was shown. Differences in the conditions of the accumulation of precious metals in the Late Holocene and modern sediments were shown. Sources of input were determined, and the possibility of technogenic enrichment of the sources was proved by the methods of multicomponent statistical analysis of the total chemical composition of the sediments. [ABSTRACT FROM AUTHOR]

In recent years, a new Algoma-type banded iron formation (BIF) deposit has been discovered in the Lanling area of the North China Craton. However, its underlying formation origins remain elusive. To effectively address this issue, in this work, the major trace and rare earth elements were analysed to characterize their sources and formation environments. From their major geochemistry results, it was proven that the Lanling BIF is mainly composed of SiO2 + Fe2O3T with small amounts of Al2O3, MnO, K2O, CaO, MgO, Na2O, P2O5, and TiO2. After performing Post-Archean Australian Shale (PAAS) normalization, according to rare earth elements (REE) and yttrium (Y) (REE + Y = REY) analyses, it was demonstrated that light rare earths are depleted. On the contrary, heavy rare earths are enriched. In addition, La, Eu, and Y are positive anomalies, while Ce is a slightly negative anomaly. According to the REE geochemistry and REE-related parameters analyses, it was extracted that the ore-forming materials of Lanling BIF were mainly derived from the mixture of seawater and hydrothermal materials. Moreover, the formation of deposits is closely associated with seafloor hydrothermal fluids. Additionally, based on the negative Ce anomalies and REY characteristics, it was speculated that BIF formed in reducing conditions in Lanling. Our work provides valuable insights suggesting that the BIF in the study area is closely related to the volcanic sedimentary rock series, as well as to the possible existence of pyroclastic materials. [ABSTRACT FROM AUTHOR]

This study investigates the diagenetic history and timing of hydrocarbon migration in the lower Permian Ingleside Formation as revealed in the Ingleside roadcut at Owl Canyon area, Colorado. Fourteen beds were identified within the studied exposure and are composed of quartz arenite sandstone, limestone, dolomite, or siltstone. Observations from outcrop and thin sections, including calcite veins, carbonate-hosted vugs, and carbonate cement, indicate carbonate mobility throughout the outcrop. Stylolites parallel to bedding were probably formed by pressure solution related to compaction, and pressure solution of carbonates is one possible source of carbonate that could have precipitated in veins or as a cement. The Ingleside Formation was affected by other diagenetic processes, including feldspar dissolution and alteration and several stages of cementation. Hematite, calcite, dolomite, kaolinite, and quartz overgrowth cements are the major types of cements identified within the studied exposure. Hematite cement was determined to have precipitated very early, followed immediately by the precipitation of poikilotopic carbonate cement. Blocky calcite and blocky dolomite cements, the most common cements within the formation, formed after the hematite and poikilotopic cements. Kaolinite cement may have precipitated in association with feldspar dissolution and alteration or occurred with feldspar dissolution during modern weathering. Hydrocarbon migration may have taken place before the of the blocky carbonate cement. The CaO in sandstone samples is due to the occurrence of calcite and dolomite cement. The MgO in sandstone samples is related to dolomite content. Furthermore, the low concentration of K2O in sandstone samples could be attributed to the low proportion of K-feldspar, and other K-rich minerals and possibly reflects loss of K during diagenesis. The relationship fact that S and MgO are both more abundant in samples from the middle and upper parts of the outcrop than in deeper samples suggests that they were added by diagenetic fluids. This study of the Ingleside outcrop provides insights on the diagenesis, possible timing of possible hydrocarbon migration through the Ingleside Formation, and geochemical and mineralogical composition of the exposure, which was used to interpret the diagenetic history throughout the outcrop. Therefore, it adds to the understanding of hydrocarbon migration and hydrocarbon pathways in this part of the Denver Basin. [ABSTRACT FROM AUTHOR]

The carbonate rocks in the eastern part of NE Turkey are situated within the Pontide paleo-magmatic arc and are frequently in contact with granitoid formations, often hosting skarn mineralization in the region. These carbonate rocks, typically found on ridges and hillsides exhibit predominant orientations along east–west, northeast-southwest, and northwest-southeast directions. A part of limestone, named as biomicrite, metamorphosed and display a saccharoidal texture. Comprised mainly of calcite, with less secondary quartz and iron oxide minerals, these carbonate rocks are classified as Fe-poor calcio-carbonate and magnesio-carbonate, having higher CaO and LOI contents. Marble and recrystallized limestone with granoblastic texture mainly comprise of calcite, less quartz, magnetite, and hematite. Marble classification diagrams suggest calcic skarn mineralization, indicated by decreasing CaO (or CO2) and increasing MgO from limestone to marble (or skarn). Strontium contents deviate slightly from the lithosphere carbonate average, while low Rb contents, attributed to skarn metamorphism, indicate the absence of K-bearing minerals. The high Al2O3/SiO2 in the carbonate rocks can points out hydrothermal activity and carbonate disengagement can indicate to actualize at temperatures that can affect Ce and Al mobilities. The low authigenic U value, low U/Th and Ni/Co ratios in carbonate rocks have been implied that protolith constituents deposited under oxic conditions. Positive Eu anomalies in limestone and marble suggest the influence of hydrothermal fluids. Carbon and oxygen isotope values in marble are similar with those of metamorphic and skarn marbles, indicating a magmatic origin. Overall, mineralogical and geochemical analyses propose a uniform source and/or geological process for all studied marbles. [ABSTRACT FROM AUTHOR]

The Neoarchean Qingyuan greenstone belt (QGB) is located at the northeastern margin of the North China Craton (NCC) and has experienced amphibolite- to granulite-facies metamorphism. The supracrustal rock assemblage is composed of biotite-hornblende (Bt-Hb) monzonitic gneiss, garnet-biotite-hornblende (Grt-Bt-Hb) monzonitic gneiss, Grt-Bt-Hb plagioclase gneiss, amphibolite and orthopyroxene-biotite-hornblende (Opx-Bt-Hb) plagioclase gneiss. This study involves thorough field and petrographic observations, whole-rock geochemistry and LA-ICP-MS zircon U‒Pb ages of these rocks to constrain the Neoarchean geodynamic setting of the QGB. Zircon U‒Pb dating indicates that these metavolcanic rocks formed during 2.57‒2.52 Ga and experienced subsequent regional metamorphism at 2.52‒2.47 Ga. Lithological and geochemical characteristics show that the QGB protoliths were tholeiitic to calc-alkaline basalts, andesites, dacites and rhyolites. The andesite-dacite-rhyolite assemblage exhibits high SiO2 and Mg# values, low Yb and Y contents, strongly fractionated chondrite-normalized REE patterns and depletion in Nb, Ta, Ti and P, resembling Phanerozoic adakites. These geochemical characteristics suggest an origin from the partial melting of a subducted slab interacting with mantle wedge material. The tholeiitic to calc-alkaline basalts exhibit slightly LREE-enriched chondrite-normalized REE patterns and negative Nb and Ti anomalies, like island arc basalts. These basalts might have originated by partial melting of a mantle source affected by metasomatism from subduction-derived fluids and melts. The lithological associations and geochemical characteristics imply that the Qingyuan greenstone belt developed in a continental margin arc setting. [ABSTRACT FROM AUTHOR]

Reliable reconstructions of tephrostratigraphy and emplacement mechanisms of Early to Middle Miocene volcaniclastic deposits across the Alpine-Mediterranean region may yield important clues as to the nature, spread, volume, magnitude and frequency of large silicic eruptions of the Carpathian-Pannonian Region. Here we report on a sequence of Middle Miocene volcaniclastic deposits intercalated with lacustrine strata from the Livno-Tomislavgrad Basin, part of the Dinaride Lake System. We applied a multi-proxy approach to elucidate their source, decipher their emplacement mechanism, and evaluate their basin-scale and regional correlativity. New high-precision zircon geochronology (~ 14.32 Ma) reveals their simultaneity with numerous volcaniclastic deposits (and their alteration products) widely spread across the Alpine-Mediterranean region. Additionally, their correlativity is confirmed at the scale of the Livno-Tomislavgrad Basin, based on similar lithostratigraphy, mineralogy and volcanic glass geochemistry. Newly obtained zircon Hf isotope data imply that Livno-Tomislavgrad Basin distal volcaniclastic deposits and ~ 14.36 Ma Harsány ignimbrite of the Carpathian-Pannonian Region had shared a parental eruptive center. However, different volcanic glass geochemistry, bolstered by the high-precision geochronology, suggests distinct eruption events, implying more frequent explosive volcanism of the Carpathian-Pannonian Region during Middle Miocene than previously recognized. We suggest that the ~ 14.32 Ma fine fallout tephra, deposited in the distal basin in the Dinarides (> 400 km from the source), was likely re-mobilized by water-driven hillside erosion from the extensive paleo-relief, and further transported via land-derived gravity flows. Upon entering the lake, the gravity flows likely transformed into subaqueous sediment density flows. These deposited ~ 1 to 7-m-thick overall graded volcaniclastic turbidites, thinning away from the presumed source of tephra re-mobilization. Although over-thickened, the ~ 14.32 Ma Livno-Tomislavgrad Basin volcaniclastic deposits can still serve as a reliable tephro- and tectono-stratigraphic markers due to their rapid mode of accumulation. Schematic illustration of the formation of studied ~14.32 Ma volcaniclastic successions of the SE Livno-Tomislavgrad Basin, Dinaride Lake System [ABSTRACT FROM AUTHOR]

The Sierra de Famatina of northwestern Argentina contains one of the best Cambro-Ordovician stratigraphic records of the SW Gondwana margin. Two lithotectonic belts (Calalaste–Narváez and Famatina–Valle Fértil), separated by master faults, preserve evidence of two former volcano-sedimentary basins (Eastern and Western, respectively). The Calalaste–Narváez Lithotectonic Belt consists of an Ediacaran to early Cambrian basement unconformably overlain by a 490–480 Ma cover of very low-grade volcano-sedimentary and volcanic succession that presumably formed in an extensional tectonic regime. In contrast, the Famatina–Valle Fértil Lithotectonic Belt comprises a basement consisting of the late-lower-to-middle Cambrian metasedimentary Achavil and Negro Peinado formations unconformably overlain by meta/sedimentary and metavolcanic rocks ranging in age from the late Cambrian to the Middle Ordovician (ca. 490–460 Ma). This belt includes the Famatinian Cordilleran-type magmatic arc active mainly at ca. 473–468 Ma, coeval with andesite to rhyolitic volcanism (Suri and Las Planchadas formations). Rhyolitic tuffs of ca. 473 Ma (εNdi = − 4.1) were found in the La Aguadita Formation, allowing this unit to be re-assigned to the late Floian. The oldest magmatism of the Sierra de Famatina is characterized by isotopically evolved (εNdi = − 5.1) rhyolitic tuffs of ca. 490 Ma in the Bordo Atravesado Formation, which was coeval with deposition of Mn-enriched hydrothermal cherts. This early Famatinan volcanism contrast with that of similar age and isotopically less evolved occurred in the Calalaste–Narváez Lithotectonic Belt suggesting variations of the source of magmas across the space and time within the Famatinan Orogenic Cycle. We propose that both described lithotectonic belts likely diverge northwards into Chile and Peru, wrapping around the Arequipa–Antofalla Proterozoic block. [ABSTRACT FROM AUTHOR]

Deep biospheric anaerobic microbial sulfate reduction and oxidative sulfur cycling have been studied in long sediment cores mainly acquired as part of IODP explorations. The most remarkable observation in many of these studies is the existence of an active sulfur cycle in the deep subsurface sediments that have very low organic carbon content and are presumably refractory. Here, we investigate the interstitial sulfate concentrations and sulfur isotope ratios in a 290 m-long sediment core collected from the eastern Arabian Sea at a water depth of 2663 m. Continuous decrease in porewater-sulfate concentrations with depth (up to 75 mbsf) coupled with enrichment in δ34SSO4 values suggests organoclastic sulfate reduction (OSR) processes attributed to the activity of sulfate-reducing bacteria (SRB) and retention of labile organic substrates amenable to the SRBs. Below a depth of 75 mbsf, the absence of further reduction in sulfate concentration indicates insufficient labile substrate to drive sulfate-reduction activity. An increase in sulfate concentrations at the deeper subsurface (below 128.5 mbsf) coupled with decreasing δ34SSO4 values may be attributed to the oxidation of Fe-sulfide to sulfate. The increase in porewater alkalinity in the lower part of the core has been linked to the silicate degradation process by CO2 produced via the dissolution of CaCO3. Compilation of previous studies from this core, along with our investigation, intrigues future research on organic matter reactivity and microbiological activity in deeper subsurface under oligotrophic depositional regimes. [ABSTRACT FROM AUTHOR]

The Pannonian Basin is one of the best natural laboratories in the world to study the lithospheric response to continental extension and subsequent tectonic inversion. Here we address the topic of lithospheric structure by a combined geochemical and magnetotelluric analysis, which has been carried out in the framework of the Pannon LitH2Oscope project. The main objective was to detect the resistivity distribution over the entire lithosphere by magnetotelluric measurements, considering the lithological resistivity properties and relate the results to the structure and evolution of the Pannonian Basin. The Pannon LitH2Oscope MT array was used to estimate the depth of the Lithosphere-Asthenosphere Boundary (LAB), considering the legacy MT data and compared to previous estimates for the region. Using the MT and geomagnetic response functions, major structural zones of the Pannonian basin, such as the Mid-Hungarian Shear Zone or fault systems like the Makó Trough and the Békés Basin, were also imaged. In addition, we used the apparent resistivity soundings to compare 1D resistivity models computed from geochemistry and obtained from field MT measurements. This comparison provided new constrains for the composition, fluid and melt content variations at the local lithosphere-asthenosphere boundary. The Pannon LitH2Oscope MT dataset and the results presented in this paper provide input for more complex 3D inversions and further investigations of the lithospheric structure in the Carpathian-Pannonian region. [ABSTRACT FROM AUTHOR]

Osmotic water alters the physicochemical properties and internal structures of limestone. This issue is particularly critical in tunnel construction across mountainous regions with aquifers, where pressurized groundwater can destabilize the limestone-based surrounding rock. Thus, systematic research into the physicochemical properties and pore structure changes in the limestone under pressurized water is essential. Additionally, it is essential to develop an interpretable mathematical model to accurately depict how pressurized osmotic water weakens limestone. In this research, a specialized device was designed to simulate the process of osmotic laminar flow within limestone. Then, four main tests were conducted: mass loss, acoustic emission (AE), mercury intrusion porosimetry (MIP), and fluorescence analysis. Experimental results gained from tests led to the development of a "Particle-pore throat-water film" model. Proposed model explains water-induced physicochemical and pore changes in limestone under osmotic pressure and reveals evolutionary mechanisms as pressure increases. Based on experimental results and model, we found that osmotic pressure not only alters limestone composition but also affects pore throats larger than 0.1 µm. Furthermore, osmotic pressure expands pore throats, enhancing pore structure uniformity, interconnectivity, and permeability. These effects are observed at a threshold of 7.5 MPa, where cohesive forces within the mineral lattice are surpassed, leading to the breakdown of erosion-resistant layer and a significant increase in hydrochemical erosion. [ABSTRACT FROM AUTHOR]

The Rare Earth Element (REE) geochemistry of siliciclastic sediment in the Ilaje area, eastern Dahomey basin, southwestern Nigeria was conducted to determine the provenance, geotectonic setting as well the REE economic potential in the sediments. Geochemical analysis results (ppm) revealed the concentration of La varies from 1.87–21.47 while Ce ranges from 1.16–45.98. Others include; Pr (1.07–39.56), Nd (0.71–26.02), Sm (0.42–12.51), Eu (0.20–4.66), Gd (0.27–8.79), Tb (0.29–3.97), Dy (0.28–3.62), Ho (0.22–2.76), Er (0.29–2.64), Tm (0.33–3.83), Yb (0.37–3.75) and Lu (0.29–3.03) respectively while the ∑REE ranges from 2.25 to 6686.75 ppm. The REE normalization plot is characterized by an inclined shape depletion indicating depletion trend. The patterns show an enriched Light Rare Earth Elements (LREE) and Heavy Rare Earth Element (HREE) pattern indicating upper continental crust sourced materials. The plot also revealed a negative Eu anomaly which may be associated with plagioclase fractionation in the acidic source rocks. The high ∑REE in the sediments has uncovered the economic potential of the sediments as a useful raw material resource for technological advancement. [ABSTRACT FROM AUTHOR]

Bulk geochemistry, Sr, Nd, and O–H isotope systematics are reported for the first time on banded iron formation (BIF)-hosted high-grade iron ore at the north-western segment of Congo Craton (CC). Located in Mbalam iron ore district, Southern Cameroon, Metzimevin iron ore deposit is a hematite-magnetite BIF system, dominated by SiO2 + Fe2O3 (97.1 to 99.84 wt%), with low concentrations of clastic elements e.g., Al2O3, TiO2, and HFSE, depicting a nearly pure chemical precipitate. The REE + Y signature of the iron deposit displays strong positive Eu anomaly, strong negative Ce anomaly, and chondritic to superchondritic Y/Ho ratios, suggestive of formation by mixed seawater-high temperature hydrothermal fluids in oxidising environment. The 87Sr/86Sr ratios of the BIF are higher than the maximum 87Sr/86Sr evolution curves for all Archean reservoirs (bulk silicate earth, Archean crust and Archean seawater), indicating involvement of continentally-derived components during BIF formation and alteration. The ƐNd(t) (+ 2.26 to + 3.77) and Nd model age indicate that chemical constituents for the BIF were derived from undifferentiated crustal source, between 3.002 and 2.88 Ga. The variable and diverse O and H isotope data (− 1.9‰ to 17.3‰ and − 57‰ to 136‰ respectively) indicate that the Metzimevin iron ore formed initially from magmatic plumes and later enriched by magmatic-metamorphic-modified meteoric fluids. Mass balance calculations indicate mineralisation by combined leaching and precipitation, with an average iron enrichment factor of > 2.67 and SiO2 depletion factor of > 0.99. This is associated with an overall volume reduction of 28.27%, reflecting net leaching and volume collapse of the BIF protholith. [ABSTRACT FROM AUTHOR]

The scientific question of precisely determining the northern boundary of the Qinling Orogenic Belt (QOB) with regard to the southern segment of the North China Craton (S-NCC) has been controversial and unresolved, as it is heavily covered by loess and lacks some geological evidence. In order to identify the concrete northern boundary of the QOB, this paper first reports the metabasalt discovered in the Qianhe River Basin in Northwestern China, on the foundation of petrography, mineralogy, geochronology and geochemistry analyses. Detailed regional geological survey presents that the Qianhe metabasalt (QMB) is in unconformable contact with the Mesoproterozoic Gaoshanhe Group. Moreover, there is the new laser ablation (LA) inductively coupled plasma mass spectrometry (ICP-MS) U-Pb dating for magmatic zircons that yielded a weighted mean age of 450 ± 9 Ma, revealing that the QMB occurred in the Late Ordovician rather than that in the Mesoproterozoic period as previously considered. Both major and trace elements show that the samples are characterized by the back-arc basin (BAB) basalt affinity. In addition, combined with the regional geology analysis, it stands to reason that the QMB is very similar to those of Ordovician Caotangou Group along the northern QOB (N-QOB). Accordingly, it is illuminated that the QMB belonging to the N-QOB, is more likely originated from the back-arc basin setting, and truly defines the QOB's northern boundary in this segment, which has prominent geoscientific significance for determining the tectonic boundary in the heavily loess-covered regions. [ABSTRACT FROM AUTHOR]

The Jiao-Liao-Ji Belt (JLJB) is one of the Paleoproterozoic orogenic belts within the North China Craton (NCC), whose tectonic evolution is still controversial due to multiple magmatic/metamorphic events after its formation. To tackle this controversy, we conducted petrological, geochronological, geochemical and zircon Hf isotopic studies for the meta-mafic rocks from the North Liaohe Group (NLG) in the central JLJB. 207Pb/206Pb weighted average ages of 1849 ± 36 Ma and 1853 ± 13 Ma indicate that the protoliths of the amphibolites in the Shisixian area formed at ca. 1.85 Ga. Geochemically, the amphibolites belong to tholeiitic series; while the meta-gabbros can be divided into the low-Ti and high-Ti types: the former belongs to calc-alkaline series, whereas the latter belongs to tholeiitic series. The high-Ti rocks are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs; e.g., Ba, K and Pb), and depleted in heavy rare earth elements (HREEs) and high field strength elements (HFSEs; e.g., Nb, Ta, P and Ti). These rocks display slightly positive εHf(t) values (+1.40 to +2.02). The low-Ti meta-gabbros were most likely derived from the partial melting of the enriched lithospheric mantle in the spinel stability field, which was metasomatized by subduction-related fluids and/or melts with significant contamination of crustal material, while the amphibolites and high-Ti meta-gabbros were derived from partial melting of depleted asthenospheric mantle in the spinel stability field, which was metasomatized by limited subduction-related fluids and/or melts, coupled with fractional crystallization. The lithological and geochemical characteristics show that the low-Ti meta-gabbros formed in a magmatic arc environment, the high-Ti rocks formed in the later stage of a back-arc basin; while the amphibolites formed in a post-collisional extensional environment. Combined with literature data, we suggest that the JLJB experienced a process from subduction, collision, to extension: At ca. 2.2–2.1 Ga back-arc basin opened via southward subduction of an oceanic plate followed by northward subduction at ca. 2.1–1.91 Ga, and subsequently closed to form the JLJB at ca. 1.91 Ga, which led to the Longgang-Nangrim continental collision, and post-collision extension occurred at ca. 1.85 Ga along with the collapse of the collisional orogen. [ABSTRACT FROM AUTHOR]

Prior model construction is a fundamental component in geophysical inversion, especially Bayesian inversion. The prior model, usually derived from available geological information, can reduce the uncertainty of model characteristics during the inversion. However, the prior geological data for inferring a prior distribution model are often limited in real cases. Our work presents a novel framework to create 3D geophysical prior models using soil geochemistry and borehole rock sample measurements. We focus on the Bayesian inversion, which enables encoding of knowledge and multiple non-geophysical data into the prior. The new framework developed in our research comprises three main parts, namely correlation analysis, prior model reconstruction, and Bayesian inversion. We investigate the correlations between surface and subsurface geochemical features, as well as the correlation between geochemistry and geophysics, using canonical correlation analysis for the surface and borehole geochemistry. Based on the resulting correlations, we construct the prior susceptibility model. The informed prior model is then tested using geophysical forward modeling and outlier detection methods. In this test, we aim to falsify the prior model, which happens when the model cannot predict the field geophysical observation. To obtain the posterior models, the reliable prior models are incorporated into a Bayesian inversion framework. Using a real case of exploration in the Central African Copperbelt, we illustrate the workflow of constructing the high-resolution 3D stratigraphic model conditioned on soil geochemistry, borehole data, and airborne geophysics. [ABSTRACT FROM AUTHOR]

An editorial focuses on the newly discovered Jinshui tin deposit located in the middle section of the East Kunlun Orogenic Belt in northwestern China. It highlights the mineralization age of the deposit, determined through U-Pb dating of zircon and cassiterite, and discusses its implications for exploration in this region. It reports that the Jinshui deposit represents a significant addition to the known tin deposits in the area, with the ages of mineralization and magmatic activity.

The article focuses on the role of microbial sulfate reduction (MSR) in carbon sequestration within marine sediments. It examines how MSR contributes to the formation of authigenic carbonates, enhances organic carbon retention through organic sulfur formation, and influences overall carbon burial efficiency. It highlights its significance in long-term carbon storage and climate regulation, particularly in the context of expanding anoxic zones due to climate change.

The results of detailed mineralogical and geochemical studies of precious metals from ultrabasic rocks of the Ariadnoe massif (Sikhote-Alin orogenic belt) are presented. The presence of several varieties of gold with different ratios of Ag, Cu, and Hg has been revealed. Isoferroplatinum predominates among platinum minerals. The isotopic composition of ultrabasite sulfides corresponds to the mantle source, while basites are characterized by isotope–light sulfur, indicating the possibility of participation in the oreogenesis of crustal rocks. Isotope-carbon analysis of igneous rocks indicates that they contain derivatives of deep fluids and isotope-light biogenic matter of sedimentary rocks. The presented data show that mantle and crustal processes were involved in the formation of ore-bearing intrusions of ultrabasic–basic rocks. The association of ilmenite, gold, and platinum in ultrabasites and basites, a derivative of these processes, can serve as a search criterion for the detection of industrially promising sources of strategic metals. [ABSTRACT FROM AUTHOR]

A comprehensive study of the Maastrichtian–Danian boundary rocks in the Klementyev Mountain section (eastern Crimea) was carried out. The lithological characteristics of carbonate, carbonate–clayey, and clastic rocks are scrutinized. The dynamic of changes in the benthic and planktonic foraminiferal assemblages is analyzed. The geochemical and isotopic data were obtained for this section for the first time. The stratigraphic range of the upper Maastrichtian and lower Danian has been specified. The late Campanian–early Maastrichtian age of the underlying rocks has been confirmed for the first time. Sediments of the Klementyev Formation were deposited in a deep-sea pelagic paleoenvironment on the submerged part of the outer shelf, whereas the overlying Lower Danian sediments were deposited in shallow waters of the inner shelf with terrigenous sedimentation and high hydrodynamic activity. [ABSTRACT FROM AUTHOR]

The Cornubian Batholith (SW England) is an archetypal Variscan rare metal granite with potential for Li-mica mineralization. We present a petrographic, trace element and multivariate statistical study of micas from the Cornubian Batholith granite series and related hydrothermally altered units to assess the role of magmatic vs subsolidus processes and of fluxing elements (F and B) on the Li cycle during the evolution of the system. The mica types are as follows: (1) magmatic, which include Fe-biotite, protolithionite I and phengite-muscovite from the most primitive granites, and zinnwaldite I from more fractionated lithologies; (2) subsolidus, which encompass high-temperature autometasomatic Li-micas and low-temperature hydrothermal muscovite-phengite. Autometasomatic species include protolithionite II, zinnwaldite II and lepidolite, which were observed in the most fractionated and hydrothermally altered units, and occur as replacements of magmatic micas. Low-temperature hydrothermal Li-poor micas formed via alteration of magmatic and autometasomatic micas or as replacement of feldspars, and albeit occur in all studied lithologies they are best represented by the granite facies enriched in metasomatic tourmaline. The evolution of micas follows two major trends underlining a coupling and decoupling between the Li(F) and B fluxes. These include as follows: (1) a Li(F)-progressive trend explaining the formation of protolithionite I and zinnwaldite I, which fractionate Li along with Cs, Nb and Sn during the late-magmatic stages of crystallization, and of zinnwaldite II and lepidolite forming from the re-equilibration of primary micas with high-temperature Li-B-W-Tl-Cs-Mn-W-rich autometasomatic fluids; (2) a Li(F)-retrogressive trend explaining the low-temperature hydrothermal muscovitization, which represents the main Li depletion process. Trace element geochemistry and paragenesis of late muscovite-phengite support that muscovitization is a district-scale process that affected the upper parts of the granite cupolas through acidic and B(Fe-Sn)-saturated hydrothermal fluids associated with metasomatic tourmalinization, which were mixed with a low Eh meteoric component. [ABSTRACT FROM AUTHOR]

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 SO42− > 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. Article Highlights: Provides information on stable isotope and geochemical modeling, as well as a comparison of two Ethiopian catchments. The key finding of the study is the stable isotope composition, water type, geochemical process, and various ion activity of groundwater. It is fundamental research for a data-scarce and understudied semi-arid climatic area. [ABSTRACT FROM AUTHOR]

This research investigates the present status and decadal variability of element distributions in the marine sediments off Doha, on the east coast of Qatar. Twenty elements were considered from 11 sediment sampling stations and 3 dust sampling stations by grouping them into major elements, toxic elements, and other trace elements. The results show elevated concentrations of certain toxic and trace elements, including Ba, Be, Co, Cr, Cu, Fe, Mg, V, Zn, Mg, and Ti, in the nearshore region, primarily influenced by the settling of dissolved elements under weak hydrodynamic circulations in the Doha Bay. The relatively higher currents in offshore enable quick advection and dispersion of the elements. On the other hand, the dust deposits have caused significant contributions to the Al, As, Mg, Ca, Sr, Fe, Zn, and Cd concentrations. Decadal variability is evident in element concentrations, which are linked to the urbanisation of the capital city in the State of Qatar. The Cu, Ni, V, Zn, and Cd concentrations indicate a notable increase in recent years compared to the last two decades, with values of about 20.7, 17.9, 25.0, 25.9, 0.66 ppm in 2022. In contrast, a few other elements fluctuate between the decades/years. The results pointed out the increased elemental concentrations in the bay due to the vast expansion of infrastructure facilities in the vicinity of Doha Bay in recent years. The Geoaccumulation Index resulted in a slight pollution of Cd, while other elements are unpolluted. The Degree of Contamination reveals low degree of contamination of sediments, and the Pollution Load Index illustrates no significant pollution in the sediments off Doha. [ABSTRACT FROM AUTHOR]

The contemporary scientific investigations delves into the mechanisms of migration, distribution, and fractionation of rare earth elements and yttrium (REE + Y) in aqueous environments characterized by humid and arid sedimentogenesis. This particular facet has been employed to solve numerous fundamental inquiries pertaining to lithology and paleolimnology. The manner in which REE + Y behave in water bodies within the cryolithozone remains largely unexplored. By evaluating the concentration levels and distribution patterns of REE + Y in the waters and sediments of the lakes situated in the Ukok Plateau and the Ulagan depression, under the prevailing conditions of cryolithogenesis as the primary geochemical process transforming rocks, soils, and sediments, we were able to augment the existing comprehension of nival sedimentation. In all the lakes examined, the content of REE + Y in the water exhibits a similar magnitude as that of small lakes in other landscape zones of the southern Western Siberia, while the content level of REE + Y is greater in the bottom sediments. The concentrations, distribution and fractionation of REE + Y vary from lake to lake and are determined by several factors: the chemical properties of REE + Y in solutions, the intensity of transformation of host rocks and the mineral forms of the REE + Y in the rocks (minerals). The concentrations, distribution and fractionation of REE + Y in bottom sediments vary slightly from lake to lake except for the contents of Eu, Y, La. The content of Eu, Y, La in the bottom sediment of the lake is influenced by a combination of factors, including their concentrations in the water, the redox conditions of diagenesis, and the mineral composition of the bottom sediment, particularly the amount of accessory minerals. [ABSTRACT FROM AUTHOR]

This paper documents the zircon U–Pb ages, whole-rock geochemistry, and Sr–Nd–Pb isotopes of the Mesozoic granites in the central part of the North Qilian Orogenic Belt to provide information on the tectonic evolution and crustal accretion process of the Qilian Orogenic Belt. Zircon U–Pb dating yields an age of 215.3 ± 3.1 Ma, indicating that the Beidaban monzogranites formed from Late Triassic. They are characterized by high contents of SiO2, Al2O3, and K2O; are slightly peraluminous (A/CNK = 1.08–1.15); and have mineralogical assemblages of primary biotite and ilmenite, illustrating that they are shoshonitic and peraluminous S-type granite. The Beidaban monzogranites have initial (87Sr/86Sr)i values ranging from 0.71456 to 0.71867 and εNd(t) values ranging from –12.9 to –8.5 with two-stage Nd model ages of 1.69–2.04 Ga, suggesting that they originated from partial melting of the Paleo-Mesoproterozoic (Longshoushan Group) continental crustal metasedimentary rocks. Initial Pb isotopic compositions (206Pb/204Pb = 19.44–21.80; 207Pb/204Pb = 15.76–15.89; 208Pb/204Pb = 39.62–41.26) and geochemical features such as high Th/Ta (9.3–67.4, 37.4 on average) and Rb/Nb (12.5–17.1) are consistent with recycled crustal components. Combined with previous geochronological and geochemical data, we suggest that the Mesozoic granites probably formed in a post-collisional tectonic setting and that the North Qilian Orogen Belt experienced comprehensive intracontinental orogenesis after the closure of the Qilian ocean. [ABSTRACT FROM AUTHOR]

Salinity is a crucial property of water body and is essential for the restoration of paleoecology and paleoenvironment. However, the theoretical method of application of elemental geochemical proxies to paleosalinity reconstruction is still underdeveloped. Moreover, accurate determination and reconstruction of paleosalinity and its variation in an offshore lacustrine basin have been extremely challenging thus far. This study presents detailed elemental geochemical investigations from the Zhanhua Sag in the southern Bohai Bay Basin to reconstruct the salinity variation in the Paleogene Eocene Shahejie Formation (50.8–33.9 Ma). Based on the variation of strontium barium ratio (Sr/Ba) and boron gallium ratio (B/Ga), we determined three typical salinity types of water body: salty water (Sr/Ba>0.5, B/Ga>6), brackish water (0.2

Reservoir modeling consists of two key components: the reproduction of the historical performance and the prediction of the future reservoir performance. Industry-standard reservoir simulators must run fast on enormous and possibly unstructured grids while yet guaranteeing a reasonable representation of physical and chemical processes. However, computational demands limit simulators in capturing involved physical and geochemical mechanisms, especially when chemical reactions interfere with reservoir flow. This paper presents a mathematical workflow, implemented in IORSim, that makes it possible to add geochemical calculations to porous media flow simulators without access to the source code of the original host simulator. An industry-standard reservoir simulator calculates velocity fields of the fluid phases (e.g., water, oil, and gas), while IORSim calculates the transport and reaction of geochemical components. Depending on the simulation mode, the geochemical solver estimates updated relative and/or capillary pressure curves to modify the global fluid flow. As one of the key innovations of the coupling mechanism, IORSim uses a sorting algorithm to permute the grid cells along flow directions. Instead of solving an over-dimensionalized global matrix calling a Newton–Raphson solver, the geochemical software tool treats the species balance as a set of local nonlinear problems. Moreover, IORSim applies basis swapping and splay tree techniques to accelerate geochemical computations in complex full-field reservoir models. The presented work introduces the mathematical IORSim concept, verifies the chemical species advection, and demonstrates the IORSim computation efficiency. After validating the geochemical solver against reference software, IORSim is used to investigate the impact of seawater injection on the NCS Ekofisk reservoir chemistry. Article Highlights: The IORSim sorting algorithm decouples the nonlinear geochemical reaction calculations into recurring one-dimensional problems to assure numerical stability and computation efficiency. To the best of our knowledge, this work presents the mathematical concept, implementation, and application of topological sorting for the first time on (industry) field-scale problems. IORSim combines topological sorting with basis swapping and splay trees to significantly reduce computation times. Moreover, a high-speed forward simulation mode was developed to allow the post-advection of chemical components to visualize species distribution, water chemistry, and mineral interactions. If the geochemical reactions interfere with the fluid flow, the IORSim backward mode uses relative permeability curves to update the global fluid flow at each time step. We validate the implemented topological scheme on a reservoir grid, show the computation efficiency, and compare the impact of explicit, implicit, and grid refinement on numerical dispersion. The decoupled flow simulator and geochemical reaction calculations allow seamless integration of full-field reservoir models that contain complex geological structures, a large number of wells, and long production histories. The computation capabilities of IORSim are demonstrated by simulating and reproducing the impact of seawater injection in the southern segment of the giant Ekofisk field (more than 50 years of injection and production history). IORSim shows that seawater injection changed the Ekofisk mineralogy and impacted the produced water chemistry. In the investigated Ekofisk case, seawater promoted calcite dissolution and led to the precipitation of magnesite and anhydrite. Moreover, surface complexation modeling revealed that sulfate is adsorbed on the calcite surface. [ABSTRACT FROM AUTHOR]

Exploration in the mining sector results in the accumulation of extensive databases encompassing diverse geochemical datasets. The efficient processing of this multivariate data necessitates the application of advanced Python data analysis tools. Such an approach is essential for the extraction of criteria that will inform and optimize future exploration and mining operations. In this study, we utilize the Python language to explore the database of Aura Energy Company established within the uranium exploration project in the regions of Oued El Foula and Aïn Sder, where a total of 1065 drilling wells have been executed. The uranium deposit in Oued El Foula and Aïn Sder is of a surficial type and results from alteration and erosion of granites. Overall, economic concentrations of uranium are near the surface (with a depth of less than 10 m) and hosted in unconsolidated rock (mainly in colluviums) and igneous rocks (mainly granites). The uranium deposit exhibits an economic association with vanadium and thorium. The granites in the regions of Oued El Foula and Aïn Sder form from the melt at the upper continental crust. In addition, these granites show enrichment in LILE and depletion in HFSE which is a characteristic of alkaline granites resulting from wet melting and evolved melt. [ABSTRACT FROM AUTHOR]

Gold mineralisation in Goz-Beida within the southern Ouaddai massif in eastern Chad is hosted by quartz veins oriented NW-SE to NE-SW in Abilelaï and ENE-WSW to NE-SW in Kalaka. Quartz in the veins from both sites is brecciated with foliated wall-rock selvages and cut across Neoproterozoic metasedimentary rock. Alteration minerals include quartz, pyrite, chalcopyrite, galena, covellite, telluride, hematite, magnetite, sericite and chlorite, with the quartz and pyrite assemblage closely associated with gold mineralisation. The phases of hydrothermal alteration include silicification, sulphidation, ferruginisation, sericitisation and chloritisation. Parameters that consistently define alteration in the wall-rock include silicification, sulphidation, carbonitisation and K-feldspar alterations. Paragenetic and micro-structural characterisation of the vein minerals reveals that the gold-bearing veins might have been emplaced during brittle/ductile deformation events within a shear zones. The gold grains are alloyed with Ag. Gold grains that occur as inclusions in pyrite from Abilelaï show fineness values that vary between 438 and 860 and are characterised by inclusions of galena and telluride. The occurrence of galena as inclusions in gold and pyrite reflects a hydrothermal quartz vein sulphide system possibly related to a fluid system with inputs from the granitoids in the area. Free gold grains from Kalaka show fineness values that range from 903 to 922. The primary Ag content of the gold is typical of granitoid-related vein systems. Such high fineness values can be attributed to sulphidation as the dominant mechanism for ore deposition. Electron microprobe analysis on sulphide phases in the vein and wall-rock in Abilelaï depicts a Au-Ag-Pb assemblage. Analysis on sulphides and telluride phases in quartz veins from Kalaka reveals a characteristic Au-Ag-Pb-Te assemblage. Thus, brecciated stockwork sulphide and telluride-bearing veins and the wall-rock within an arc setting in prospective mining sites are the main target for gold in Goz- Beida. [ABSTRACT FROM AUTHOR]

Rare earth elements (REE) of the host rocks (Fe-siliceous rocks) and manganese ores of the Nchwaning Mine (Hotazel Formation, Kalahari manganese field) were studied. An important feature of manganese ores and host rocks (Fe-silicites) is the presence of negative and positive cerium (Ce/Ce*) and europium (Eu/Eu*) anomalies. This testifies to the complex and long history of the formation of manganese ores. Initial metal-bearing (Mn, Fe) sediments of a shallow-water basin with a negative cerium anomaly (Ce/Ce*) were enriched in europium (positive Eu/Eu*) at different stages of lithogenesis both during sedimentation (underwater discharge of hydrothermal fluids), and subsequent processes of hydrothermal transformation of the ore-bearing strata. The source of manganese could be basaltic andesites of the underlying Ongeluk Formation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A notable decrease of groundwater Na/K ratios was observed several months before the 2018 Hokkaido Eastern Iburi earthquake (M6.7) at a site approximately 20 km west of the earthquake's epicenter. To investigate the cause of the decreased Na/K ratios, we analyzed groundwater samples (commercially bottled drinking water) to assess the contribution of deep-derived fluids using Li and Sr isotopic ratios, which are reliable indicators of deep fluid contributions. No pronounced changes in the 7Li/6Li and 87Sr/86Sr ratios were observed; thus, the pre-earthquake decrease of groundwater Na/K ratios did not result from the input of deep-derived fluids. The pre-earthquake decrease in the Na/K ratio observed in this study may instead be related to CO2 influx into the aquifer. The CO2 may have leaked from carbon dioxide capture and storage (CCS), because CCS was in operation near the epicenter of the 2018 Hokkaido Eastern Iburi earthquake. Decreases of the Na/K ratios and increases of the CO2 concentrations in groundwater have been reported before other large earthquakes; thus, CO2 influx into groundwater may be a common phenomenon preceding earthquakes. [ABSTRACT FROM AUTHOR]

Neoproterozoic island arc assemblage of the Arabian–Nubian Shield (ANS) in the Eastern Desert (ED) of Egypt comprises juvenile suites of metavolcanics (MV), large amounts of meta-sedimentary rocks (MS), and voluminous metagabbros-diorites (MGD) and syn-tectonic intrusions of older granitoids (OG). We report here the updates of these four rock units in terms of classification, distribution, chemical characteristics, geodynamic evolution, metamorphism, and ages. In addition, we discuss these integrated data to elucidate a reasonable and reliable model for crustal evolution in the ANS. The main features of these rock units indicate their relation to each other and the geodynamic environment dominated by early immature oceanic island arcs to primitive continental arcs. Integrated information of the island arc metavolcanic and plutonic rocks (gabbros, diorites, tonalites, and granodiorites) furnish evidence of the genetic relationships. These include proximity and a coeval nature in the field; all protolith magmas are subalkaline in nature following calc-alkaline series with minor tholeiitic affinities; common geochemical signature of the arc rocks and subduction-related magmatism; their similar enrichment in LREEs; and similar major element compositions with mafic melts derived from metasomatized mantle wedge. The volcano-sedimentary and the OG rocks underwent multiphase deformation events whereas the MGD complexes deformed slightly. Based on the magmatic, sedimentological, and metamorphic evolutions constrained by geochronological data as well as the progressive evolutionary trend from extensional to compressional regimes, a possible gradual decrease in the subducted slab dip angle is the most influential in any geodynamic model for arc assemblage in the ED of Egypt. [ABSTRACT FROM AUTHOR]

Meso-Neoarchean fuchsite quartzites are present in different stratigraphic positions of Dharwar Craton including the oldest (~ 3.3 Ga) Sargur Group of western Dharwar Craton. The present study deals with the petrographic and geochemical characteristics of the fuchsite quartzites from the Ghattihosahalli belt to evaluate their genesis, depositional setting and the enigma involved in the ancient sedimentation history. Their major mineral assemblages include quartz, fuchsite, and feldspars along with accessory kyanite and rutile. The geochemical compositions are characterized by high SiO2, Al2O3, low MgO, CaO, strongly enriched Cr (1326–6899 ppm), Ba (1165–3653 ppm), Sr (46–210 ppm), V (107–868 ppm) and Zn (11–158 ppm) contents compared to the upper continental crust (UCC). The UCC normalized rare earth element (REE) patterns are characterized by depleted light REE [(La/Sm)UCC = 0.33–0.95] compared to heavy REE [(Gd/Yb)UCC = 0.42– 1.65)] with conspicuous positive Eu-anomalies (Eu/Eu* = 1.35–18.27) characteristic of hydrothermal solutions evidenced through the interlayered barites. The overall major and trace element systematics reflect a combined mafic-felsic provenance and suggest their deposition at a passive continental margin environment. The comprehensive field, petrographic, and geochemical studies indicate that these quartzites are infiltrated by Cr-rich fluids released during high-grade metamorphism of associated ultramafic rocks. The Sargur and the subsequent Dharwar orogeny amalgamated diverse lithounits from different tectonic settings, possibly leading to the release of Cr-rich fluids and the formation of fuchsite quartzite during or after the orogeny. These findings suggest a pre-existing stable crust prior to the Sargur Group and the link between orogenic events and various mineral deposits in the Dharwar Craton. [ABSTRACT FROM AUTHOR]

In the central north of Saudi Arabia, outcrop samples from the Cretaceous bauxite profile deposits in the Az Zabirah area were subjected to a comprehensive evaluation aimed at investigating their petrographical and geochemical characteristics using X-ray diffraction analysis (XRD), Scanning electron microscope (SEM) coupled with Energy dispersive (EDS) analysis, and X-ray fluorescence spectrometer (XRF) analysis. These bauxite deposits in the Az Zabirah area comprises of three main zones: the South zone, the Central zone, and the North zone. Petrologically, the bauxite samples predominantly consist of oolitic to pisolitic grains that are bound together by a matrix comprising bauxitic materials, iron oxides, calcite, and/or kaolinite. Mineralogical investigations indicate that the primary mineral composition of the bauxite includes gibbsite, boehmite, diaspore (kaolinite), hematite, quartz, and calcite. XRF showed that the dominant chemical components of the bauxite samples are Al2O3, SiO2, and Fe2O3. When considering the collective data from the rare earth elements (REEs) analysis (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) and chemical weathering indices such as the Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Weathering Index of Parker (WIP), it becomes evident that the Az Zabirah South Zone bauxite laterite profile at Al Ba'itha mine was formed under the influence of significant and persistent weathering conditions. The findings and methods used in this study are considered beneficial and valuable as they support mineral exploration in arid and semi-arid environments. [ABSTRACT FROM AUTHOR]

The publication presents the results of geochemical, isotopic-geochemical (Sm–Nd) and isotopic-geochronological (U–Th–Pb) studies of terrigenous rocks of the Middle Riphean (?) Nadarov Formation and the Upper Riphean (?) Nortui Formation of the northwestern part of the Argun continental massif. The composition of the deposits indicates the presence of formations of various silica content in the source area. According to Sm–Nd data, sedimentary rocks of the Nadarov and Nortui formations are characterized by negative values of εNd(t) = –6.6...–3.5 at Early Proterozoic values of Nd model age (tNd(DM) = 2.0–1.8 Ga). The U–Th–Pb dating of detrital zircon grains showed that the lower age limit of accumulation of terrigenous deposits of the Nadarov and Nortui formations falls to the Late Riphean (~775 and ~ 744 Ma, respectively). The main provenance areas for them were Late Riphean igneous rocks, with participation of Early Proterozoic rocks occurring in the Argun Massif. [ABSTRACT FROM AUTHOR]

Granulites exposed in high-grade regional metamorphic belts and exhumed as xenoliths in basaltic pipes are considered as window into the deep crust thus play a key role in constraining models of crustal processes and evolution. Here we present a detailed investigation of the tectono-metamorphic history of the two-pyroxene mafic granulite located in the southern region of the Sonapahar area. This involves conducting monazite chemical dating, analyzing petrological and geochemical characteristics, applying geothermobarometry, performing phase equilibria modeling, and tracing a pressure-temperature (P-T) path. Metamorphic P-T conditions estimated for the mafic granulite using conventional thermobarometer and winTWQ shows temperature in excess of 800°C and pressure of about 8.6 kbar, stand for high temperature granulite facies metamorphism. The metamorphic evolution path obtained from P-T pseudosection suggest a clockwise P-T evolution path, thus signify isothermal decompression and indicate rapid upliftment. Geochemical study of trace and rare earth elements (REE), suggest protolith is of tholeiite basalt in nature that is derived from back arc basin setting near to subduction zone. Additionally, the analyzed rock was examined using primitive mantle-normalized trace element spider diagram. The results indicate an enrichment in large-ion lithophile elements (Th, U, K, Pb) and a depletion in high field-strength elements (Nb, Ta, Ti). The presence of negative anomalies in Nb and Ti, coupled with elevated values of Th, K, and Pb, suggests the possibility of crustal contamination. Monazite chemical data from the studied rock reveals a peak metamorphism age of 521.3 ± 4.20 Ma, which corresponds to the Kuunga Orogeny in the later phase of global Pan-African collision. [ABSTRACT FROM AUTHOR]

The Mongol-Okhotsk Ocean, which has been closing gradually from the west to the east beginning since the Late Paleozoic, was an important part of the Central Asian Orogenic Belt. It influenced the tectonic framework of Northeast Asia in the Mesozoic, especially the Late Mesozoic arc-basin system that is widely distributed in the Great Xing'an Range. However, the manner in which the Mongol-Okhotsk Ocean affected the sedimentary basin development remains poorly understood. To address this issue, we conducted U-Pb dating of detrital zircon deposited sedimentary basins of the central Great Xing'an Range. By examining the possible provenances of the detrital zircon and the structural controls of the basins, we found that a key sedimentary unit was deposited around Late Jurassic-Early Cretaceous. Its provenance was a felsic source in a back-arc setting of an active continental margin. The findings also suggest the existence of a unified geodynamic setting that affected the coeval development of basins in the northern Great Xing'an Range and the Yanshan fold-thrust belt along the northern margin of North China Craton. This research helps to better understand the complex tectonic processes which shaped the Northeast Asia during the Late Mesozoic. [ABSTRACT FROM AUTHOR]

The Hardawu granites in the eastern segment of the ultrahigh-pressure metamorphic belt, the northern Qaidam Basin, were studied by whole-rock major and trace elements and in-situ zircon U-Pb geochronology and Hf isotopes to discuss the petrogenesis and tectonic evolution. Geochronological results show that the granites have a crystallization age of 401 ± 3 Ma, suggesting that they were formed in the Early Devonian. The granites have SiO2 contents of 75.32 wt.%–76.05 wt.%, total alkali contents of 8.23 wt.%–8.36 wt.%, and K2O/Na2O ratios of 1.62–1.91. They were rich in K2O, poor in TiO2, MnO, MgO, and P2O5, and have A/CNK values of 1.05–1.07, Rittmann index δ values of 2.05–2.14, and differentiation index (DI) values of 92.85–94.18. They are high potassium calc-alkaline, weak-peraluminum, and highly differentiated I-type granites. The granites also show enrichment of large ion lithophile elements (LILE) such as Rb, Ba, and Th, and depletion of high field strength elements (HFSE) such as Nb, Ta, and Ti. The total REE concentrations range from 169 ppm to 232 ppm, with enrichments of light rare earth elements and negative Eu anomalies (δEu = 0.39–0.55). The zircon εHf(t) values range from −0.65 to −2.29, and the two-stage model ages (tDM2) changed within a small range of 1.44 to 1.54 Ga, indicating that the magma of the Hardawu granites was originated from the partial melting of Mesoproterozoic lower crustal materials. Combined with previous studies, we suggest that the Hardawu granites were formed in the extensional tectonic setting after the collision between the Qaidam Block and the central and southern Qilian Block in the Early Devonian. [ABSTRACT FROM AUTHOR]

The Gaoaobei tungsten-molybdenum deposit is a newly discovered large-scale quartz-vein-type deposit in the Nanling metallogenic belt in South China. The ore bodies are hosted in the Indosinian granites and the Cambrian Xiangnan Group slates and are controlled by NWW-oriented faults, which are obviously different from the "five-story building" model in southern Jiangxi Province. The magmatic rocks in the study area are dominated by medium- to coarse-grained biotite monzogranite, with a few NW-oriented fine-grained granite dykes. The medium- to coarse-grained biotite monzogranite and fine-grained granite dykes have zircon U-Pb ages of 229.4 ± 1. 9 Ma (MSWD = 1.5) and 164.9 ± 3.3 Ma (MSWD = 0.75), respectively, corresponding to the Indosinian and Yanshanian magmatism. The monzogranites have higher contents of FeO, CaO, K2O, P2O5, and TiO2, while the granite dykes have slightly higher contents of SiO2, Al2O3, MnO, and Na2O. Their A/CNK values are 1.11–1.75 and 1.19–2.25, and the contents of CIPW normative corundum are 1.71%–6.66% and 2.41%–9.50%, suggesting both the monzogranites and granite dykes are S-type granite. The total amount of rare earth elements in the monzogranites (from 84.7 ppm to 129 ppm) is slightly lower than that in the granite dykes (from 128 ppm to 133 ppm). The Eu/Eu* values range from 0.12 to 0.30 in monzogranites and from 0.001 1 to 0.001 3 in granite dykes, indicating the fine-grained granites underwent more intense fractional crystallization. The monzogranite and granite dykes have high 87Sr/86Sri values of 0.716 9–0.719 3 and 0.728 25–0.728 80, low εNd(t) values ranging from −10.2 to −9.6 and from −11.5 to −11.4, and TDM2 ages of 1 835–1 785 and 1 957–1 946 Ma, respectively. These isotope data indicate their origin from the remelting of the Paleoproterozoic crustal materials. Combined with regional geology, it is concluded that the medium- to coarse-grained biotite monzogranite was formed in a post-collisional extensional environment. In addition, 40Ar-39Ar dating of the greisen type tungsten-molybdenum ore gave consistent plateau age of 164.0 ± 1.2 Ma, isochronal age of 162.0 ± 2.4 Ma and anti-isochronal age of 161.4 ± 1.8 Ma. Combined with the published molybdenite Re-Os age, the Gaoaobei tungsten-molybdenum deposit was formed at ∼164 Ma, which is inferred to be genetically related to the contemporaneous finegrained granite dykes (165 Ma). The deposit was likely formed during the large-scale magmatism and mineralization event in the early Yanshanian of the Nanling Range in an intra-continental extensional environment caused by the subduction of the paleo-Pacific plate. The late and small granite dykes within the large granite plutons thus require further attention during mineral prospecting in the regions. [ABSTRACT FROM AUTHOR]

The Sangong Cu-Ni sulfide mineralized mafic-ultramafic intrusion is located on the southern margin of the Bogeda-Harlik belt, eastern Tianshan, China. The intrusion is a well-differentiated complex and is comprised of leucogabbro, gabbro, olivine gabbro, Pl-bearing peridotite, and Pl-bearing pyroxenite. The Pl-bearing pyroxenite hosts both irregularly disseminated sulfide and round droplet sulfide. The intrusive rocks have a wide range of SiO2 (42.1 wt.%–50.48 wt.%) and MgO (6.21 wt.%–22.11 wt.%), and are enriched in light rare earth elements (LREE), large-ion lithophile elements (LILE; e.g., Rb, Ba, Sr, and Pb), and palladium platinum group elements (PPGE) but depleted in high-field-strength elements (HFSE; e.g., Nb, Ta, and Ti) and iridium PGEs (IPGE). These geochemical characteristics indicate that the Sangong mafic-ultramafic intrusion was derived from high degree of partial melting of depleted mantle and interacted with subduction-related material. The low Pd/Ir (3.21–27.44) but high Ni/Cu (1.64–24.16) ratios, combined with the olivine crystals with low Fo (60.88–78.65) and Ni (54.99 ppm–1 688.87 ppm) concentrations suggest that the parental magma of the Sangong intrusion were likely high MgO basaltic in composition that experienced extensive evolution prior emplacement. The Ce/Pb ratios (5.8–13.6) and Nb/U ratios (11.6–30.3) of the intrusive rocks all range between MORB and crustal values, the Nb/Yb and Th/Yb values are close to the lower crust values, together with the low Se/S ratios [(17–100) × 10−6)] suggest that the magma experienced assimilation not only in mantle source but also in conduit, but the degree of crustal contamination is limited. The Cu/Pd ratios of the rocks range from 3.9 × 104 to 10.8 × 104, and the Cu/Zr ratios of Pl-bearing pyroxenite in the Sangong intrusion are >1, combined with the presence of sulfide droplets in the Pl-bearing pyroxenite, indicating the parental magma experienced sulfide saturation and the economical ore bodies may present in the depth of the intrusion. Furthermore, given the discovery of the Baixintan and Yueyawan deposits, we propose the Dananhu-Harlik belt as an essential prospecting target for Cu-Ni mineralization in North Xinjiang. [ABSTRACT FROM AUTHOR]

The Erlian Basin is a Mesozoic–Cenozoic rift basin with a large thick Pliocene sandstones deposit, which has important oil, gas, and uranium resources exploration potential. The paleo-sedimentary environment plays an important role in controlling the development of mineral resource. However, provenance and depositional environment of the Pliocene sandstones remain enigmatic. To address it, this study reports the whole rock geochemical compositions of sandstones from the Youqi and Siziwangqi regions to reflect the paleo-sedimentary environment. The Youqi sandstones are classified as litharenite-arkose, whereas the Siziwangqi sandstones exhibit a graywacke affinity. Furthermore, both the Youqi and Siziwangqi sandstones exhibit low CIA, PIA, ICV, and Th/U values, suggesting that their source rocks were of great maturation and experienced low to moderate chemical weathering processes. The Ni/Co, U/Th, and Ce/Ce* values in these sandstones range from 0.4 to 5.9, 0.20 to 0.37, and 0.80 to 1.09, respectively, indicating that these sandstones were formed in an oxygen-rich depositional environment. Additionally, interelement ratios such as Sr/Cu, SiO2/Al2O3, and Rb/Sr suggest a hot and arid paleoclimate during the deposition of these sandstones. Tectonic discrimination diagrams reveal a continental arc environment for the studied sandstones, Combining regional structural background, implying that the Erlian Basin was influenced by both Himalayan and the Pacific-Ocean-surrounding tectonism during the Pliocene period. [ABSTRACT FROM AUTHOR]

Aillikite dikes of carbonate–biotite composition, intersecting Paleoproterozoic banded iron formations, were discovered in the Kursk block of Sarmatia for the first time. Their age is 2.10–2.07 Ga. The aillikite dikes underwent epidote–amphibolite facies metamorphism (550°С, 2–3 kbar), and they are deformed and foliated. Primary magmatic olivine and pyroxene were not preserved. In terms of geochemistry, ultramafic lamprophyres of the Kursk block are similar to petrotypical aillikites. They are depleted in SiO2 and Al2O3 and enriched in MgO, TiO2, K2O, Cr, Ni, and Nb with highly fractionated LREE and HREE. The highly radiogenic neodymium isotopic composition is indicative of a juvenile enriched (metasomatized) mantle source of aillikites. Positive Nb and Ti anomalies suggest metasomatic alterations of the depleted lithosphere mantle by OIB melts under opening of the Tim back-arc basin. The aillikite dikes and carbonatites of the Dubravinsky complex could have been formed at different melting degrees of a single deep, lithospheric source, enriched in lithophile elements shortly before the melting episode, possibly in a suprasubduction setting about 2.1 Ga. [ABSTRACT FROM AUTHOR]

The mineralogy of some carbonate rocks from the Abakaliki Basin has been investigated to determine the depositional environment classification and assess the suitability of the rocks for application in geotechnical construction and industrial process systems. The method of investigation included field mapping and petrographic and geochemical techniques to characterize their field characteristics, mineral types and texture and chemical contents. Mapping revealed two lithologic units of sandstone and shale that associate with the carbonates in a similar sequence. The carbonates contain fossils and are composed of calcite, quartz and rockclasts. The grains have angular to sub-rounded sphericity and are dispersed in hetereolithic groundmass. The major oxide composition shows average value of 32.30wt% SiO2, 26.37wt% CaO, 7.23wt% MgO, 6.56wt% Fe2O3, 4.38wt% Al2O3, and 3.23wt% K2O + Na2O in decreasing order of abundance. Concentrations of trace elements are significantly higher (> 100 ppm) for V, Cr, Sr, Zr, Cu, Ba, Pb and Zn and comparatively lower for Sb, Ge, Ce, Y, As, Hg, Tiand Au. The studied rocks qualify as biomicrite or wackestone and range from dolomitic, through carbonaceous to siliceous limestone deposited in a wide spectrum of environment from shallow marine to transitional setting. The rocks are marginally suitable for use as aggregates due to the presence of deleterious contents of quartz and organics. For cement production, their low content of CaO, relatively high SiO2, comparatively high LOI and elevated abundances of contaminant heavy elements are major limitations. Similarly, in paper, plastic, paint, metallurgy and pharmaceutics, the rocks are unsuitable due to the constituent minerals. [ABSTRACT FROM AUTHOR]

Devonian thick–layer dolostone is widely developed in the Shawozi Formation (SWZF) of the Sichuan Basin, however, the properties of the dolomitisation fluid and its genesis require clarification. This study adopted field observations, microscopic identification, and geochemical data analysis methods that major and trace elements, rare–earth element (REE) analyses, carbon and oxygen isotopes based on 31 samples. The results showed that dolomites were divided into crystalline dolomites and calcareous dolomites. Crystalline dolomite, which is the most widely distributed, can be further divided into fine crystalline dolomite (FCD), fine–medium crystalline dolomite (FMCD), medium crystalline dolomite (MCD), and coarse crystalline dolomites (CCD). Calcareous dolomite, fine crystalline dolomite (FCD), and fine–medium crystalline dolomite (FMCD) have higher Fe, higher Mn, and lower Sr, whereas medium crystalline dolomite (MCD) and coarse crystalline dolomite (CCD) have the opposite characteristics. The REE content was lower and weak negative anomalies of Ce and Eu were apparent, indicating that dolomite was formed in a fragile redox environment and at a relatively low temperature. The δ13CPDB value had a small variation range, with an average value of 0.04‰. Although the variation range of δ18OPDB value was more extensive, most samples were concentrated in the range of -6.53‰~-2.1‰, indicating that the overall effect of diagenetic alteration was more negligible. Two dolomitisation models were developed: reflux seepage and burial dolomitisation. The reflux seepage model mainly developed calcareous dolomite, whereas the burial model mainly developed crystalline dolomite. The degree of dolomitisation increased with increasing burial depth and formation pressure. [ABSTRACT FROM AUTHOR]

As the last part of the Hercynian cycle in the Yangtze region, the Dongwu Movement included the eruption of the Emeishan large igneous province (ELIP) and was an essential event between the Guadalupian and Lopingian, which had significant implications for the paleo-oceanic environment and paleoclimate of the area. To study the changes in the sedimentary environment in the Guadalupian and Lopingian, the Zhenba section was selected, and its trace elements and rare earth elements (REEs) were analyzed. From analysis of the trace elements and REEs in the Guadalupian, the limestone samples had prominent typical shallow-water seawater deposition characteristics and were less affected by terrigenous detritus, which was in an arid oxidation environment; Sr/Cu ranged from 4 to 1381, the Rb/Sr value was low, δCe < 1, Ceanom < −0.1, Er/Nd ranged from 0.1 to 0.27, and Y/Ho ranged from 44 to 72. However, in the Lopingian, the limestone samples were more affected by terrigenous detritus, which was in a humid climate with a weak oxidation‒reduction environment; the Sr/Cu ranged from 1 to 656, the Rb/Sr value was high, δCe ≅ 1, Ceanom ≥ −0.1, Er/Nd < 0.1, and Y/Ho ranged from 26 to 44. The geochemical diagrams of TiO2‒Al2O3, Al2O3‒REE, La‒Th‒Sc, Th‒Co‒Zr/10, Th‒Sc‒Zr/10 and 87Sr/86Sr of a sample indicated that the terrigenous detritus of the sample mainly came from the South Qinling active continental margin, rather than the weathering of Emeishan basalt. Acid bentonite came from the Paleo-Tethys island arc or the island arc formed by the subduction of the South China Plate beneath the North China Plate, rather than the ELIP. This evidence supported the view that the North China Plate potentially collided with the South China Plate in middle to late Wujiaping. [ABSTRACT FROM AUTHOR]

The paper presents new data on a comparative analysis of sedimentary rocks from the Mendeleev Rise (Shamshura Seamount), presumably, of the Triassic age with the Aptian sandstones obtained by the underwater sampling of the Alpha–Mendeleev Rise during expeditions in 2012, 2014, and 2016. The geochemical characteristics of rocks are very similar, and the data from different-age samples form common fields on various diagrams. Petrographic studies revealed that the sandstones of presumably Late Triassic age, as well as the sandstones of Chukotka and Wrangel Island, are dominated by fragments of shale and felsic effusives. The Aptian samples are dominated by mafic rock fragments. In addition, sharp differences are observed in the age spectra of detrital zircon populations, indicating fundamentally different provenances for the Triassic and Cretaceous sandstones on the Alpha–Mendeleev Rise. Samples from the Shamshura Seamount are characterized by populations similar to those from Triassic rocks of Chukotka and Wrangel Island, suggesting the presence of Triassic rocks in this part of the Mendeleev Rise. [ABSTRACT FROM AUTHOR]

In the geochemical review based on records from cruises of the International Deep Marine Drilling Project (DSDP, ODP, and IODP phases) and other literature data on the main types of Pleistocene sediments in the Atlantic, tables of average arithmetic chemical composition, mean weighted chemical composition, accumulation rates, and mass accumulation rates of chemical components are presented. These tables can be used for the comparative analysis with sediments of the same or other stratons in different oceanic basins, as well as with paleoceanic sediments on the continents. The terrigenous matrix dominates within the lithogenic matter. Using methods of mathematical statistics, we revealed the main geochemical associations and major factors determining the chemical composition of studied sediments. Masses of oxides of petrogenic elements and several trace elements have been calculated for Pleistocene sediments. Average chemical composition of Pleistocene sediments is proposed for the Atlantic. [ABSTRACT FROM AUTHOR]