Acta Geochimica最新文献

This review critically examines strategies for sustainable groundwater and surface water management, emphasizing their integration to achieve environmental sustainability. The study synthesizes findings from a wide range of research articles, identifying key trends, gaps, and controversies within the field. It highlights the importance of cohesive management approaches that take into account climate change, policy impacts, and methodological advancements. The review aims to provide a structured, analytical discussion that aligns with the thematic focus of integrated water management. By offering original insights and practical recommendations, this review seeks to contribute to the development of more effective and sustainable water management practices. The analysis underscores the necessity of interdisciplinary approaches that integrate hydrological, ecological, and socio-economic factors. Furthermore, the review discusses the role of adaptive management and technological innovations in enhancing the resilience and efficiency of water management systems. The findings suggest that a comprehensive understanding of the interactions between groundwater and surface water is crucial for developing strategies that ensure long-term environmental sustainability. This review concludes with recommendations for future research and policy development, emphasizing the need for adaptive, resilient, and integrated water management strategies that can address the challenges posed by climate change and other environmental pressures.

The deep geologic processes between the Xing’an-Mongolian Orogenic Belt and the North China Craton in the Mesozoic are crucial to reveal the magmatic and tectonic evolution and their constraints on mineralization in the Jiapigou-Haigou collage zone. In this paper, We have presented the geochronology, geochemistry and Sr–Nd–Hf isotopic compositions of the Middle Jurassic granitic complexes in the Songjianghe area, Jilin Province. The granitic complexes can be categorized into four groups based on their geologic characteristics, with corresponding zircon U–Pb isotope ages of 177 Ma, 172 Ma, 169 Ma and 168–167 Ma, respectively. These granitoids exhibit calc-alkaline to high-K calc-alkaline, metaluminous to weakly peraluminous I-type characteristics, which show relative enrichment in LILEs (Rb, Sr, Ba) and depletion in HFSEs (Nb, Zr). Geochemical analyses reveal high initial ⁸⁷Sr/⁸⁶Sr ratios of 0.70633–0.70740, coupled with low εNd(t) values ranging from −10.65 to −13.23. The zircon analyses show similarly negative εHf(t) values ranging from −16.9 to −3.2. The integrated elemental and Hf–Sr–Nd isotopic signatures demonstrate that the primitive magmas of the four group rocks were primarily derived from partial melting of thickened Archean lower crust, with the exception of the Group IV rocks, which exhibit significant evidence of crustal contamination. The residual mineral assemblages during the magma-forming process varied from amphibole to eclogite facies. These findings indicate that magmatism in the Songjianghe region likely resulted from the accretion and delamination of the Archean crust in the collage zone during the subduction of the Paleo-Pacific Plate beneath the Eurasian continent.

The Cretaceous Koum Basin is a rift-related half-graben in northern Cameroon, which constitutes a portion of the Yola Arm of the Upper Benue Trough. This study presents the first comprehensive dataset combining mineralogical, bulk-rock geochemical, and stable C–H–O isotopic data for dark-gray, fine-grained mudstones from the basin, providing new insights into its sediment source, paleoenvironment, and geodynamic setting. The mudstones primarily consist of phyllosilicates (~ 8.6%), feldspars (~ 30.5%), carbonates (~ 13.7%), and minor iron oxides (~ 2.7%), with vermiculite, illite, and kaolinite as the main clay minerals. The presence of analcime, ankerite, and dolomite suggests low-grade metamorphism and/or hydrothermal alteration. Fe₂O₃/K₂O (1.52–6.40) and SiO₂/Al₂O₃ (2.97–4.68) ratios classify the mudstones as compositionally immature shales (ICV ~ 1.64) with low-moderate chemical weathering (CIA ~ 56.35; PIA ~ 59.74; R³⁺/R³⁺ + R²⁺ + M⁺  ~ 0.51). Trace element ratios (Th/Sc ~ 1.70, Zr/Sc ~ 1.33, La/Sc ~ 6.30, La/Th ~ 4.14) indicate an intermediate igneous provenance from a continental crustal source. Paleoenvironmental proxies suggest deposition in a dynamic basin environment marked by fluctuating redox (C_org/P: 0.21–178.34) and salinity (Sr/Ba: 0.34–3.25; N-values: 48–35.92) conditions, ranging from oxic to anoxic and brackish to saline. Major element data (SiO₂ vs. Al₂O₃ + K₂O + Na₂O) indicate a semi-arid regime, while Paleoclimatic indicators such as Sr/Cu (1.88–37.47) and C-values (0.12–0.93) suggests alternating humid and arid conditions. Notably, stable isotope data, reported here for the first time in the Koum Basin, reveal a predominantly terrestrial, fluvial-deltaic C₃ plant source for organic carbon (δ¹³C − 25.2‰ to − 35.2‰) and complex fluid-rock interactions involving meteoric and magmatic-metamorphic fluids under a warm, equatorial climate (δ¹⁸O + 3.6‰ to + 24.9‰, δ²H − 104‰ to − 50‰). The combined mineralogical, geochemical, and isotopic data point to deposition in a tectonically active continental arc setting, with contributions from ocean island arc and passive margin sources.

The study area is situated in the Tianshan region, specifically within the eastern segment of the North Qilian Orogenic Belt (NQLOB). The NQLOB is a critical region for understanding oceanic closure and continental collision processes driven by the Shangdan Ocean subduction-exhumation, which was a segment of the Proto-Tethys Ocean during the Early Paleozoic. Despite significant research, the Early Paleozoic tectonic background and subduction-related orogenic processes, particularly in the eastern NQLOB, remain subjects of debate. This study presents significant petrographic, geochemical, and geochronologic insights into the metavolcanic rocks of the Chenjiahe Group in the eastern NQLOB. Petrographic analysis reveals that these metavolcanic rocks originated in a low-grade metamorphic setting. Zircon laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb dating yielded ages ranging between 449.7–443.4 Ma, indicating Late Ordovician formation. Geochemical signatures of felsic and intermediate rocks exhibit calc-alkaline to high-K calc-alkaline similarities, characterized by high light rare earth elements (LREEs), low heavy rare earth elements (HREEs), and moderate Eu anomalies, consistent with a continental arc setting. In contrast, basaltic rocks display tholeiitic features with elevated large-ion lithophile elements (LILEs), reduced high-field-strength elements (HFSEs), and weak Eu anomalies, suggesting an extensional environment. These findings imply that the metavolcanic rocks evolved in a continental arc-back-arc extension setting connected with the northward subduction and exhumation of the Huluhe back-arc oceanic basin. This process was likely triggered by the northward subduction and closure of the Shangdan Ocean, culminating in the Late Ordovician amalgamation of the Qilian Block and the southwestern North China Block. This study provides critical insight into the tectonic development of the NQLOB and the broader Proto-Tethys Ocean dynamics at the northern periphery of the Eastern Gondwana.

Mafic rocks generated from subduction settings have recorded valuable source information about the mantle source. In this study, we present a comprehensive analysis of zircon U–Pb dating, whole-rock major and trace elements, and Sr–Nd isotopic data for the mafic gabbro located in the Yumen area, on the western part of the Yangtze Block, South China, aiming to constrain the processes of mantle metasomatism within subduction settings. U–Pb dating results for zircon yield crystallization ages of 800 Ma for type 1 mafic gabbro and 753–734 Ma for type 2 mafic gabbro. Type 1 mafic gabbro exhibits higher SiO₂ (44.13%–48.93%) and Al₂O₃ content but lower total Fe₂O₃ and MgO content than type 2 gabbro (SiO₂: 41.02%–43.28%). These gabbros display a high-Mg^# signature (52.50–62.81 for type 1, 50.89–57.04 for type 2), while they are enriched in significant large-ion lithophile elements (LILEs: Rb, Ba, Sr, K) and depleted in high-field-strength elements (HFSEs: Zr, Hf, Nd, Ta, Ti), which indicates an arc-like element signature. The positive whole-rock εNd(t) values (type 1: 3.5–4.4, type 2: 5.6–6.3) combined with a narrow range of (⁸⁷Sr/⁸⁶Sr)_i (type 1: 0.7035–0.7043, type 2: 0.7035–0.7036) of both gabbro types suggest a depleted lithospheric mantle origin. Therefore, these mafic rocks may derive from a metasomatized spinel lherzolite mantle source (with amphibole) due to the interactions of the deep mantle source and subduction fluid materials. We propose that the long-term metasomatism recorded by mafic gabbro in this study supports the fact that the subduction during the Neoproterozoic contributed to the formation of a metasomatized mantle source in the Yumen area, western Yangtze Block, South China.

Numerous Indosinian igneous rocks in the North Qaidam (NQ) provide crucial insights into the tectonic evolution of the Paleo-Tethys Ocean. This paper presents a comprehensive study of the petrography, mineralogy, geochemistry, zircon U–Pb geochronology, and Hf isotope composition of dioritic rocks from the eastern NQ. Zircon U–Pb dating results indicate that the dioritic rocks were formed during the Middle Triassic (244–240 Ma). The rocks exhibit high-K calc-alkaline characteristics with variable SiO₂ (55.25–65.39 wt%) and elevated K₂O + Na₂O (4.81–6.94 wt%) contents. They show enrichment in LILEs (Rb, Ba, K) and depletion in HFSEs (Nb, Ta, Ti), with slight negative Eu anomalies (Eu/Eu* = 0.89–0.97). Zircon ε_Hf(t) values (−20.93 to + 5.60) and T_DM2 ages (0.85–1.72 Ga) suggest mixed sources. Petrographic and mineralogical analysis reveals that the plagioclase phenocrysts exhibit disequilibrium textures (including reverse zoning), primarily composed of andesine and labradorite, with a small amount of oligoclase. The clinopyroxenes are all augites and have high crystallization temperatures (1111–1151 °C). These features, particularly the reverse zoning of plagioclase, support a petrogenetic model involving mantle-derived magma underplating that induced melting of ancient lower crust, followed by mixing of underplated basaltic magma with crust-derived felsic magma. Our results indicate formation in a back-arc extensional setting during subduction of the Zongwulong Paleo-Tethys Ocean.

The present study of metabasalts was carried out to understand the mantle source and geodynamic setting of the Mahakoshal Group in the Central Indian Tectonic Zone. In this study, we present detailed field, petrography, and whole rock geochemistry of the Mahakoshal metabasalts. The Mahakoshal metabasalts are sub-alkaline in nature and belong to the tholeiitic series of rocks. The variation in rare-earth element patterns of metabasalts indicates the different degrees of partial melting at shallow as well as deeper depths. Further, Eu/Eu* varies from 0.8 to 1.1 (except sample KP-144=0.3), Ce/Ce* varies from 0.97 to 1.05, showing no cerium anomaly, and Nb/Nb* ranges from 0.7 to 1.3 (except KP-144=0.1). The magnesium number (Mg#) varies from 0.2 to 0.3, which is quite low, indicating the evolved nature of the metabasalts. The studied metabasalts show E-MORB to OIB-type affinities, which are placed in the trench-distal back-arc setting. The opening of the Mahakoshal Basin is due to retreating orogen in the accretionary orogen setting and is contemporaneous with the assembly of the Columbia Supercontinent (~2.1–1.8 Ga). Hence, field, petrographic, and geochemical signatures indicate that the Mahakoshal basin opened as a back-arc rift basin on the Bundelkhand Craton, and that metabasalts are derived from the mantle that underwent variable degrees of partial melting at different depths.

The western margin of the Yangtze Block hosts diverse Neoproterozoic igneous rocks, with exposed S-type granites serving as key indicators for deciphering regional geological evolution. This study focuses on the Jiudaowan granite pluton, located on the western margin of the Yangtze Block, through systematic petrographic, whole-rock geochemical, zircon and monazite U–Pb geochronology, and whole-rock Nd isotopic analyses aiming to elucidate its petrogenesis and tectonic significance. The Jiudaowan granite pluton is a composite body, consisting of the Luotaijiu, Jiudaowan, and Daheishan units, characterized by biotite monzogranites, muscovite–plagioclase granites, and two-mica monzogranites, respectively. LA-ICP-MS zircon and monazite U–Pb dating reveals crystallization ages between 832 and 798 Ma. The three units are peraluminous, containing minerals such as muscovite, garnet, and tourmaline, and exhibiting high SiO₂ (72.99–77.83 wt%), Al₂O₃ (12.36–15.02 wt%), and A/CNK values (1.06–1.43), confirming their classification as peraluminous S-type granites. Compositional variations within the Jiudaowan granite pluton are primarily controlled by protolith composition and melting mechanisms. The pluton is distinguished by low CaO/Na₂O ratios (0.02–0.18), high Rb/Sr (0.83–113) and Rb/Ba (0.33–15.2) ratios, and negative ε_Nd(t) values (−13.6 to −9.1), indicating derivation from partial melting of heterogeneous metasedimentary sources. MgO, TiO₂, Rb/Sr, and whole-rock Zr saturation temperatures suggest that the Luotaijiu and Daheishan units formed via biotite dehydration melting, whereas the Jiudaowan unit resulted from muscovite dehydration melting. Additionally, the Jiudaowan granite pluton displays a clear negative correlation between Al₂O₃, CaO, Fe₂O₃T, MgO, TiO₂, and SiO₂, along with pronounced Eu negative anomalies and depletions in Sr and Ti, suggesting fractional crystallization of feldspar, mica, and Fe-Ti oxides during magma emplacement. Similarly, variable incompatible element ratios of Nb/U (1.07–18.97) and Nb/La (0.24–26.88) further indicate minor crustal assimilation and contamination during magma evolution. Integrating regional geological data, we propose that the Jiudaowan pluton formed during crustal thickening associated with post-collisional extension, likely related to the breakup of the Rodinia supercontinent.

With the development of aviation, superconducting, and other steel industries, the demand for niobium (Nb) has significantly increased worldwide, positioning it as a critical strategic metal. The Bayan Obo rare-earth elements (REE)-Nb-iron (Fe) deposit contains over 70% of China’s Nb resources and hosts the world’s largest reserves of REE. However, due to technical and environmental challenges, a substantial portion of the Nb resources remains underutilized and stored in tailings. Research and development of efficient, environmentally friendly, low-energy consumption, and less complex methods for extracting Nb from the Bayan Obo tailings possess significant scientific value and strategic importance. This paper reviews the current research status and distinctive geological and mineralogical characteristics of Nb resources in the Bayan Obo deposit, as well as existing pyrometallurgical and hydrometallurgical technologies for extracting Nb from ores and tailings, subsequently comparing their advantages to guide the development of new processes. Based on a comprehensive consideration of the technical, economic, environmental, quality, and safety aspects, it is suggested that future research should prioritize establishing a systematic recommendation procedure for targeted Nb-bearing mineral characterization and analysis for the Bayan Obo tailings, developing fluoride-free or low-fluoride hydrometallurgical techniques, and exploring innovative methods for Nb mineral coarsening. This review thus provides new insights into the efficient utilization of the Bayan Obo Nb resources and supports the development of innovative and effective strategies for optimizing Nb extraction from ores and tailings.

Tectono-geochemical analysis is one of the key technical methods for deep prospecting and prediction, but the extraction of information on weak and low degrees of mineralization remains a significant challenge. This study takes the Maoping super-large germanium-rich lead–zinc deposit in northeastern Yunnan as an example, systematically analyzes the mineralization element assemblages and their anomaly distribution characteristics, extracts information on low and weak anomalies at depth, clarifies the spatial distribution of ore-forming element anomalies and fluid migration patterns, and establishes tectono-geochemical deep anomaly evaluation criteria and prospecting models, thereby proposing directions for deep prospecting in the deposit. This research shows that the mineralization element assemblage of the F1 factor (Cd-Cu-Ge-Zn-Sb-In-Pb-Sr(-)-As-Hg) anomalies represents near-ore halos; the element assemblage of the F2 factor (Ni-Co-Cr-Rb-Ga) anomalies represents tail halos; the element assemblage of the F3 factor (Rb-Mo-Tl-As) anomalies represents front halos; and the element assemblage of the F4 factor (Ba-Ga) anomalies represents barite alteration anomalies. Elements such as Zn and Pb exhibit significant anomalies near the lead–zinc ore bodies. In the study area, vertical anomalies in the eastern region of the Luoze River indicate that ore-forming fluids migrated from the SE at depth to the NW at shallower levels, whereas in the western region, ore-forming fluids migrated from the SW at depth to the NE at shallower levels. Thus, the lateral extensions of different ore bodies in the eastern and western regions of the river have been determined. On this basis, tectono-geochemical deep anomaly evaluation criteria for the deposit are established, and directions for deep prospecting are proposed. This study provides scientific value and practical significance for deep prospecting and exploration engineering planning for similar lead–zinc deposits.