Search Results (1,209)

Petrological knowledge on weathering processes controlling the mobility of chemical elements is still limited in the dry tropical zone of Cameroon. This study aims to investigate the mobility of major and trace elements during rhyolite weathering and soil formation in Mobono by understanding the mineralogical and elemental vertical variation. The studied soil was classified as Cambisols containing mainly quartz, K-feldspar, plagioclase, smectite, kaolinite, illite, calcite, lepidocrocite, goethite, sepiolite, and interstratified clay minerals. pH values ranging between 6.11 and 8.77 indicated that hydrolysis, superimposed on oxidation and carbonation, is the main process responsible for the formation of secondary minerals, leading to the formation of iron oxides and calcite. The bedrock was mainly constituted of SiO₂, Al₂O₃, Na₂O, Fe₂O₃, Ba, Zr, Sr, Y, Ga, and Rb. Ce and Eu anomalies, and chondrite-normalized La/Yb ratios were 0.98, 0.67, and 2.86, respectively. SiO₂, Al₂O₃, Fe₂O₃, Na₂O, and K₂O were major elements in soil horizons. Trace elements revealed high levels of Ba (385 to 1320 mg kg⁻¹), Zr (158 to 429 mg kg⁻¹), Zn (61 to 151 mg kg⁻¹), Sr (62 to 243 mg kg⁻¹), Y (55 to 81 mg kg⁻¹), Rb (1102 to 58 mg kg⁻¹), and Ga (17.70 to 35 mg kg⁻¹). LREEs were more abundant than HREEs, with LREE/HREE ratio ranging between 2.60 and 6.24. Ce and Eu anomalies ranged from 1.08 to 1.21 and 0.58 to 1.24 respectively. The rhyolite-normalized La/Yb ratios varied between 0.56 and 0.96. Mass balance revealed the depletion of Si, Ca, Na, Mn, Sr, Ta, W, U, La, Ce, Pr, Nd, Sm, Gd and Lu, and the accumulation of Al, Fe, K, Mg, P, Sc, V, Co, Ni, Cu, Zn, Ga, Ge, Rb, Y, Zr, Nb, Cs, Ba, Hf, Pb, Th, Eu, Tb, Dy, Ho, Er, Tm and Yb during weathering along the soil profile. Full article

The eastern Tianshan region in the Central Asian Orogenic Belt (CAOB) is characterized by multiple complex tectonic activity of uncertain historical contribution to the construction of the CAOB. This study utilizes a multi-proxy geochemical approach to characterize I-type monzogranite pluton rocks and their associated hornblende-rich dioritic enclaves to decipher the tectonic and magmatic evolution of the Xigebi area, eastern Tianshan. Zircon geochronology indicates a Triassic and Permian crystallization age of ca. 224.2 ± 1.7 Ma and ca. 268.3 ± 3.0 Ma for the host monzogranites and the dioritic enclaves, respectively. Major, trace and rare earth element distribution, together with Hf isotope systematics displaying noticeable positive εHf(t) anomalies for both rock types, point to partial melting of meta-mafic rocks in an intraplate extensional setting. The diorite was formed by the melting of lower crustal meta-igneous rocks mixed with mantle melts, and the monzogranite, predominantly from deep crustal meta-basalts contaminated by shallow metasedimentary rocks, with some degree of mixing with deeply sourced mantle magma. While both the host monzogranites and their dioritic enclaves are the products of upwelling magma, the younger Triassic monzogranites captured and preserved fragments of the dioritic Permian lower continental crust during crystallization. These multiple stages of magmatic underplating and crustal reworking associated with vertical stratification of the juvenile paleo-continental crust suggest the monzogranites and diorites indicate a change from a post-collisional setting to a regional intraplate regime on the southern margin of the CAOB. Full article

The southern Great Xing’an Range is located in the overlap zone of the Paleo-Asian Ocean metallogenic domain and the Circum-Pacific metallogenic domain. It hosts numerous Sn-polymetallic deposits, such as Weilasituo, Bianjiadayuan, Huanggang, and Dajing, and witnessed multiple episodes of magmatism during the Late Mesozoic. The study area is situated within the Huanggangliang-Ganzhuermiao metallogenic belt in the southern Great Xing’an Range. The region has witnessed extensive magmatism, with Mesozoic magmatic activities being particularly closely linked to regional mineralization. We present petrographic, zircon U-Pb chronological, lithogeochemical, and Lu-Hf isotopic analyses of the Yexilinhundi granites. The results indicate that the granite porphyry and granodiorite were emplaced during the Late Jurassic. Both rocks exhibit high SiO₂, K₂O + Na₂O, differentiation index (DI), and 10,000 Ga/Al ratios, coupled with low MgO contents. They show distinct fractionation between light and heavy rare earth elements (LREEs and HREEs), exhibit Eu anomalies, and have low whole-rock zircon saturation temperatures (T_zr), collectively demonstrating characteristics of highly fractionated I-type granites. The εHf(t) values of the granites range from 0.600 to 9.14, with young two-stage model ages (T_DM2 = 616.0~1158 Ma), indicating that the magmatic source originated from partial melting of Mesoproterozoic-Neoproterozoic juvenile crust. This study proposes that the granites formed in a post-collisional/post-orogenic extensional setting associated with the subduction of the Mongol-Okhotsk Ocean, providing a scientific basis for understanding the relationship between the formation of Sn-polymetallic deposits and granitic magmatic evolution in the study area. Full article

This article presents the potential use of a humic agent called ‘Superhumate’, obtained from weathered coal from the Shubarkol deposit in Kazakhstan. The experiment was conducted using model solutions and surface mine water samples from the “Degelen” site at the Semipalatinsk Test Site. The adsorption of heavy metals and toxic elements using the “Superhumate” agent was carried out under dynamic conditions using a chromatographic column. Tests were conducted at a natural pH range of 5–8 (mine waters) and with a model solution at pH 1.7. Assessing the sorption efficiency of this preparation revealed that at pH 1.7, the agent does not adsorb elements such as Cd, Cu, Pb, and Zn. Under dynamic experimental conditions, using the preparation for mine waters at natural pH levels (pH 5–8), elements such as Be, Sr, Mo, Cd, Cs, Zn, and U were efficiently adsorbed at levels of 60–95%. The sorption efficiency of Pb ions was found to be almost independent of pH. The experimental results obtained with mine water samples indicate that alkaline solutions have the highest sorption efficiency, with pH ≥ 7, which is attributed to the solubility of the agent. Full article

The Central Asian Orogenic Belt (CAOB) represents a crucial area for understanding the tectonic evolution of the Paleo-Asian Ocean and surrounding orogenic systems. This study investigates the petrology, geochronology, and geochemistry of volcanic and clastic rocks from Well HFD3 in the northern Songliao Basin, which provides key insights into the tectonic development of this region. Zircon U–Pb dating of tuff samples from the Linxi Formation provides an accurate age of 251.1 ± 1.1 Ma, corresponding to the late Permian. Geochemical analyses show that the clastic rocks are rich in SiO₂ (63.5%) and Al₂O₃ (13.7%), with lower K₂O/Na₂O ratios (0.01–1.55), suggesting low compositional maturity. Additionally, the trace element data reveal enrichment in light rare earth elements (LREEs) and depletion in Nb, Sr, and Ta, with a negative Eu anomaly, which indicates a felsic volcanic arc origin. The Chemical Index of Alteration (CIA) values (53.2–65.8) reflect weak chemical weathering, consistent with cold and dry paleo-climatic conditions. These findings suggest that the Linxi Formation clastic rocks are derived from felsic volcanic arcs in an active continental margin environment, linked to the subduction of the Paleo-Asian Ocean slab. The sedimentary conditions reflect a gradual transition from brackish to freshwater environments, corresponding with the final stages of subduction or the onset of orogeny. Full article

The Ouarzazate Group in the Anti-Atlas Belt of southern Morocco, part of the West African Craton (WAC), is a significant Proterozoic lithostratigraphic unit formed during the late Ediacaran period. It includes extensive volcanic rocks associated with the early stages of Iapetus Ocean opening. Zircon U-Pb dating and geochemical analyses of the Oued Dar’a Caldera (ODC) volcanic succession in the Saghro Massif reveal two major eruptive cycles corresponding to the lower and upper Ouarzazate Group. The 1st cycle (588–563 Ma) includes pre- and syn-caldera volcanic succession characterized by basaltic andesite to rhyolitic rocks, formed in a volcanic arc setting through lithospheric mantle-derived mafic magmatism and crustal melting. A major caldera-forming eruption occurred approximately 571–562 Ma, with associated rhyolitic dyke swarms indicating a larger caldera extent than previously known. The 2nd cycle (561–543 Ma) features post-caldera bimodal volcanism, with tholeiitic basalts and intraplate felsic magmas, signaling a shift to continental flood basalts and silicic volcanic systems. The entire volcanic activity spans approximately 23–40 million years. This succession is linked to late Ediacaran intracontinental super-eruptions tied to orogenic collapse and continental extension, likely in association with the Central Iapetus Magmatic Province (CIMP), marking a significant transition in the geodynamic evolution of the WAC. Full article

The Chagai porphyry copper belt is a major component of the Tethyan metallogenic domain, which spans approximately 300 km and hosts several giant porphyry copper deposits. The tectonic setting, whether subduction-related or post-collisional, and the deep dynamic processes governing the formation of these giant deposits remain poorly understood. Mafic microgranular enclaves (MMEs), mafic dikes, and multiple porphyries have been documented in the Saindak mining area. This work examines both the ore-rich and non-ore intrusions in the Saindak porphyry Cu-Au deposit, using methods like molybdenite Re-Os dating, U-Pb zircon ages, Hf isotopes, and bulk-rock geochemical data. Geochronological results indicate that ore-fertile and barren porphyries yield ages of 22.15 ± 0.22 Ma and 22.21 ± 0.33 Ma, respectively. Both MMEs and mafic dikes have zircons with nearly identical ²⁰⁶Pb/²³⁸U weighted mean ages (21.21 ± 0.18 Ma and 21.21 ± 0.16 Ma, respectively), corresponding to the age of the host rock. Geochemical and Sr–Nd–Hf isotopic evidence indicates that the Saindak adakites were generated by the subduction of the Arabian oceanic lithosphere under the Eurasian plate, rather than through continental collision. The adakites were mainly formed by the partial melting of a metasomatized mantle wedge, induced by fluids from the dehydrating subducting slab, with minor input from subducted sediments and later crust–mantle interactions during magma ascent. We conclude that shallow subduction of the Arabian plate during the Oligocene–Miocene may have increased the flow of subducted fluids into the sub-arc mantle source of the Chagai arc. This process may have facilitated the widespread deposition of porphyry copper and copper–gold mineralization in the region. Full article

The Raohe subduction–accretion complex (RSAC) in the Wandashan Block, NE China, comprises ultramafic rocks, gabbro, mafic volcanic rocks, deep-sea and hemipelagic sediments, and trench–slope turbidites. We investigate the basalts within the RSAC to resolve debates on its origin. Zircon U-Pb dating of pillow basalt from Dadingzi Mountain yields a concordant age of 117.5 ± 2.1 Ma (MSWD = 3.6). Integrating previous studies, we identify three distinct basalt phases. The Late Triassic basalt (210 Ma–230 Ma) is characterized as komatites–melilitite, exhibiting features of island arc basalt, as well as some characteristics of E-MORB. It also contains high-magnesium lava, suggesting that it may be a product of a juvenile arc. The Middle Jurassic basalt (around 159 Ma–172 Ma) consists of a combination of basalt and magnesium andesite, displaying features of oceanic island basalt and mid-ocean ridge basalt. Considering the contemporaneous sedimentary rocks as hemipelagic continental slope deposits, it is inferred that these basalts were formed in an arc environment associated with oceanic subduction, likely as a result of subduction of the young oceanic crust. The Early Cretaceous basalt (around 117 Ma) occurs in pillow structures, exhibiting some characteristics of oceanic island basalt but also showing transitional features towards a continental arc. Considering the regional distribution of the rocks, it is inferred that this basalt likely formed in a back-arc basin. Integrating the formation ages, nature, and tectonic attributes of the various structural units within the RSAC, as well as previous research, it is inferred that subduction of the Paleo-Pacific Ocean had already begun during the Late Triassic and continued into the Early Cretaceous without cessation. Full article

The accurate prediction of static formation temperature (SFT) is essential for ensuring safety and efficiency in ultra-deep well drilling operations. Excessive downhole temperatures (>150 °C) can degrade drilling fluids, damage temperature-sensitive tools, and pose serious operational risks. Conventional methods for SFT determination—including direct measurement, temperature recovery inversion, and artificial intelligence models—are often limited by post-drilling data dependency, insufficient spatial resolution, high computational costs, or a lack of adaptability to complex wellbore geometries. In this study, we propose a new pseudo-3D Kriging interpolation framework that explicitly incorporates real wellbore trajectories to improve the spatial accuracy and applicability of pre-drilling SFT predictions. By systematically optimizing key hyperparameters (θ = [10, 10], lob = [0.1, 0.1], upb = [20, 200]) and applying a grid resolution of 100 × 100, the model demonstrates high predictive fidelity. Validation using over 5.1 million temperature data points from 113 wells in the Shunbei Oilfield reveals a relative error consistently below 5% and spatial interpolation deviations within 5 °C. The proposed approach enables high-resolution, trajectory-integrated SFT forecasting before drilling with practical computational requirements, thereby supporting proactive thermal risk mitigation and significantly enhancing operational decision-making on ultra-deep wells. Full article

The lower sub-member of Member 2, Dongying Formation (Paleogene) in the HHK Depression hosts an extensively developed thin-bedded beach-bar system characterized by favorable source rock conditions and reservoir properties, indicating significant hydrocarbon exploration potential. Integrating drilling cores, wireline log interpretations, three-dimensional seismic data, geochemical analyses, and palynological data, this study investigates the sedimentary characteristics, sandbody distribution patterns, controlling factors, and genetic model of this lacustrine beach-bar system. Results reveal the following: (1) widespread thin-bedded beach-bar sandbodies dominated by fine-grained sandstones and siltstones, exhibiting wave ripples and low-angle cross-bedding; (2) two vertical stacking patterns, Type A, thick mudstone intervals intercalated with laterally continuous thin sandstone layers, and Type B, composite sandstones comprising thick sandstone units overlain by thin sandstone beds, both demonstrating significant lateral continuity; (3) three identified microfacies: bar-core, beach-core, and beach-margin facies; (4) key controls on sandbody development: paleoenvironmental evolution establishing the depositional framework, secondary fluctuations modulating depositional processes, strike-slip extensional tectonics governing structural zonation, paleobathymetry variations and paleotopography controlling distribution loci, and provenance clastic influx regulating scale and enrichment (confirmed by detrital zircon U-Pb dating documenting a dual provenance system). Collectively, these findings establish a sedimentary model for a thin-bedded beach-bar system under the strike-slip extensional tectonic framework. Full article

The Permian–Triassic magmatic record in the eastern Central Asian Orogenic Belt (CAOB) provides critical insights into the terminal stages of the Paleo-Asian Ocean (PAO) evolution, including collisional and post-collisional processes following its Late Permian closure. The northeastern China region, tectonically situated within the eastern segment of the CAOB, is traditionally known as the Xingmeng Orogenic Belt (XOR). This study integrates zircon U-Pb geochronology, whole-rock geochemistry, and zircon Hf isotopic analyses of intermediate-acid volcanic rocks and intrusive rocks from the former “Tongjiatun Formation” in the Faku area of northern Liaoning. The main objective is to explore the petrogenesis of these igneous rocks and their implications for the regional tectonic setting. Zircon U-Pb ages of these rocks range from 260.5 to 230.1 Ma, indicating Permian–Triassic magmatism. Specifically, the Gongzhuling rhyolite (260.5 ± 2.2 Ma) and Gongzhuling dacite (260.3 ± 2.4 Ma) formed during the Middle-Late Permian (270–256 Ma); the Wangjiadian dacite (243 ± 3.0 Ma) and Wafangxi rhyolite (243.9 ± 3.0 Ma) were formed in the late Permian-early Middle Triassic (256–242 Ma); the Haoguantun rhyolite (240.9 ± 2.2 Ma) and Sheshangou pluton (230.1 ± 1.7 Ma) were formed during the Late Middle-Late Triassic (241–215 Ma). Geochemical studies, integrated with the geochronological results, reveal distinct tectonic settings during successive stages: (1) Middle-Late Permian (270–256 Ma): Magmatism included peraluminous A-type rhyolite with in calc-alkaline series (e.g., Gongzhuling) formed in an extensional environment linked to a mantle plume, alongside metaluminous, calc-alkaline I-type dacite (e.g., Gongzhuling) associated with the subduction of the PAO plate. (2) Late Permian-Early Middle Triassic (256–242 Ma): Calc-alkaline I-type magmatism dominated, represented by dacite (e.g., Wangjiadian) and rhyolite (e.g., Wafangxi), indicative of a collisional uplift environment. (3) Late Middle-Late Triassic (241–215 Ma): Magmatism transitioned to high-K calc-alkaline with A-type rocks affinities, including rhyolite (e.g., Haoguantun) and plutons (e.g., Sheshangou), formed in a post-collisional extensional environment. This study suggests that the closure of the PAO along the northern margin of the North China Craton (NCC) occurred before the Late Triassic. Late Triassic magmatic rocks in this region record a post-orogenic extensional setting, reflecting tectonic processes following NCC-XOR collision rather than PAO subduction. Combined with previously reported age data, the tectonic evolution of the eastern segment of the CAOB during the Permian-Triassic can be divided into four stages: active continental margin (293–274 Ma), plate disintegration (270–256 Ma), final collision and closure (256–241 Ma), and post-orogenic extension (241–215 Ma). Full article

The Yangtze Block, with its widespread Neoproterozoic mafic–felsic magmatic rock series and volcanic–sedimentary rock assemblages, is one of the key windows for reconstructing the assembly and fragmentation process of Rodinia. This study focuses on the Taoyuan syenogranite from the Micangshan Massif on the northern Yangtze Block, by conducting systematic chronology, mineralogy, and geochemistry analyses to investigate their source, petrogenesis, and tectonic setting. LA-ICP-MS U–Pb geochronology reveals that the medium- to coarse-grained and medium- to fine-grained syenogranites have crystallization ages of 878 ± 4.2 Ma and 880 ± 6.5 Ma, respectively. These syenogranites have aluminum saturation index (A/CNK) values ranging from 0.79 to 1.06, indicating quasi-aluminous to weakly peraluminous compositions, and are classified as calc-alkaline I-type granites. The geochemical indicators of these rocks, including Mg^# (44–48, mean 46), Zr/Hf (40.07), Nb/La (0.4), and zircon εHf(t) values (+9.2 to +10.9), collectively indicate a depleted lithospheric mantle source. The mantle source was metasomatized by subduction-derived fluids and sediment melts prior to partial melting as evidenced by their higher Mg^#, elevated Ba content, and distinctive ratios (Rb/Y, Nb/Y, Th/Yb, Th/Sm, Th/Ce, and Ba/La). Integrating regional data, this study confirms crust–mantle interaction along the northern Yangtze during the early Neoproterozoic, supporting a sustained subduction-related tectonic setting. Full article

The Oligocene Dongying Formation beach-bar system, widely distributed in the HHK Depression of the Bohai Bay Basin, constitutes a key target for mid-deep hydrocarbon exploration, though its provenance remains controversial due to complex peripheral source terrains. To address this, we developed an integrated methodology combining LA-ICP-MS zircon U-Pb dating with whole-rock rare earth element (REE) analysis, facilitating provenance studies in areas with limited drilling and heavy mineral data. Analysis of 849 high-concordance zircons (concordance >90%) from 12 samples across 5 wells revealed that Geochemical homogeneity is evidenced by strongly consistent moving-average trendlines of detrital zircon U-Pb ages among the southern/northern provenances and the central uplift zone, complemented by uniform REE patterns characterized by HREE (Gd-Lu) enrichment and LREE depletion; geochemical disparities manifest as dual dominant age peaks (500–1000 Ma and 1800–3100 Ma) in the southern provenance and central uplift samples, contrasting with three distinct peaks (65–135 Ma, 500–1000 Ma, and 1800–3100 Ma) in the northern provenance; spatial quantification via multidimensional scaling (MDS) demonstrates closer affinity between the southern provenance and central uplift (d_ij = 4.472) than to the northern provenance (d_ij = 6.708). Collectively, these results confirm a dual (north–south) provenance system for the central uplift beach-bar deposits, with the southern provenance dominant and the northern acting as a subsidiary source. This work establishes a dual-provenance beach-bar model, providing a universal theoretical and technical framework for provenance analysis in hydrocarbon exploration within analogous settings. Full article

The present study investigates the extent and spatial distribution of metal concentration in stream sediments that flow into Keban Dam Lake, Turkey. Sediment samples were analysed for trace and potentially toxic elements (PTEs), including V, Cr, Co, Ni, Cu, Zn, Pb, Tl, Th, and U. Enrichment Factor (EF), Contamination Factor (CF), Geo-accumulation Index (Igeo), and Pollution Load Index (PLI) were employed to assess contamination levels. Results reveal that Cr exhibited very high enrichment (EF = 15.95) in downstream urban samples, while Cu and Zn showed high enrichment in samples collected from the middle to lower reaches of the stream, probably indicating anthropogenic contributions. Most other elements, such as Pb, Tl, Th, and U, were within natural background levels. Sediment Quality Guidelines (SQGs) indicate that Cr, Ni, and Cu may pose potential ecological risks, especially in samples from urban-influenced and downstream areas where concentrations exceed the Probable Effect Levels (PEL; Cr: 160 mg/kg, Ni: 42.8 mg/kg, Cu: 108 mg/kg). Multivariate statistical analyses, including Pearson correlation and hierarchical clustering, reveal three distinct geochemical groupings. Among these, the most contaminated cluster—corresponding to midstream and downstream regions—is characterized by elevated Cu and Zn concentrations. Strong correlations among Cu–Zn, Ni–Cu, and Th–U suggest there is a combination of anthropogenic and lithogenic sources for most metals. While most sites showed low to moderate pollution, urban downstream locations exhibited significant metal accumulation, necessitating the region’s continued environmental monitoring and management strategies. Full article

For the first time, the deposition area of heavy metals and other trace elements (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, P, Pb, S, Sr, Sb, V, Zn, and Hg) on the territory surrounding a landfill of domestic (municipal) waste at the 9th km of the Vilyuisky tract of Yakutsk within a radius of 51 km was assessed using the method of moss biomonitors and ICP-OES as an analytical technique. Mosses were analyzed for radionuclide content (⁴⁰K, ¹³⁷Cs, ²¹² Pb, ²¹⁴Pb, ²¹²Bi, ²¹⁴Bi, ²⁰⁸Tl, ⁷Be, and ²²⁸Ac) in a number of selected samples by semiconductor gamma spectrometry. The results of the examination of moss samples by ICP-OES indicate the presence of large amounts of toxic Ba and metal debris (Al, Co, Cr, Fe, S, and Pb) at the landfill. In addition, it is shown that the investigated samples contain elements such as Cd, Co, Cr, Cu, Cu, Mn, Ni, Pb, Sr, V, Zn, and Hg. The method of gamma spectrometry revealed that the studied samples contain such radioactive elements as ¹³⁷Cs, daughter products of ²³⁸U and ²³²Th. Detection of the same heavy metals and radionuclides in the atmospheric air of the city and in the vegetation near the landfill may indicate that one of the sources of environmental pollution may be products of incineration of the landfill contents at the 9th km of the Vilyuisky tract. Full article