Search Results (202)

The Beishan area of Gansu, China, is the primary candidate site for the geological disposal of China’s high-level radioactive waste (HLW). To assess the long-term safety of this repository, the evolutionary patterns of groundwater and the primary migration vector of radionuclides must be understood. Through experiments and hydrogeochemical simulations of snowmelt samples from the Qilian Mountains and deep rock samples from Beishan, we reveal different hydrochemical compositions and types of the snowmelt and deep groundwater. The results show that the hydrochemical type of Qilian Mountain snowmelt is SO₄–Na·Ca, whereas that of the deep groundwater in the Beishan is Cl·SO₄–Na, indicating substantial differences in the hydrochemical characteristics of the two samples. The water–rock interactions between snowmelt and granite are dominated by the dissolution of silicate minerals and the precipitation of carbonate minerals, accompanied by cation exchange and adsorption. After the interaction, the hydrochemical type of the snowmelt becomes SO₄–Na, with total dissolved solids (TDS) consistently maintained at ~500 mg/L, which is distinct from the TDS range of 1540–2045 mg/L observed for the deep groundwater in the Beishan. Under the experimental and simulation conditions set in this study, the water–rock interactions between Qilian Mountain snowmelt and Beishan granite cannot reproduce the hydrochemical characteristics of the deep groundwater in the Beishan. This study provides theoretical support for the hydrogeological safety assessment of HLW geological repositories. Full article

Rainfall-induced landslides represent one of the most recurrent geohazards affecting the transportation network of southwestern Calabria (Italy). This study provides an integrated assessment of landslide occurrence and road damage along the Costa Viola by combining detailed geomorphological mapping, multi-temporal analyses, historical documentation (1950–2025), and GIS-based spatial data processing. A total of 261 landslides were mapped, affecting approximately 19% of the study area. Slides constitute the dominant movement type (66.7%), followed by complex landslides, flows, and falls. Landslide distribution is strongly controlled by geological and morphometric factors: more than 80% of mapped phenomena occur in highly fractured granitic and gneissic rocks, over 70% lie within 500 m of faults, and more than 90% are located within 300 m of streams. Slope gradient (25–55°) and local relief (350–550 m) further contribute to slope instability patterns. The historical dataset documents 237 landslide-induced road damage events over 75 years, with a marked increase in occurrence since the early 2000s. Most damage events affected the SS18 road and frequently corresponded to reactivations of pre-existing landslides, highlighting the long-term persistence of slope instability and the seasonal influence of intense autumn–winter precipitation. Overall, the results demonstrate that landslide hazard in the Costa Viola is governed by the interplay between structural, lithological, geomorphic, and climatic factors, compounded by anthropogenic modifications along road corridors. The combined landslide inventory and historical database provide a robust basis for risk mitigation, identification of critical road sectors, and future susceptibility and predictive modelling to support effective territorial planning. Full article

Variscan two-mica granites are widespread in the Trás-os-Montes region (NE Portugal), yet their emplacement ages, petrogenesis, and relationship with Variscan deformation phases remain poorly constrained. This study integrates U–Pb zircon geochronology, whole-rock geochemistry, and oxygen isotope data to characterise four peraluminous two-mica granites in the Trás-os-Montes area (Fornos, Carviçais, Fonte Santa, and Bruçó) and to refine their tectonomagmatic context within the Central Iberian Zone. All granites are S-type, ilmenite-series, and derived from reduced magmas, as indicated by their strongly peraluminous compositions, mineral assemblages (muscovite ± biotite), absence of magnetite and presence of ilmenite, and high δ¹⁸O values (>11‰), consistent with partial melting of metasedimentary crust. U–Pb ages reveal two distinct magmatic pulses: an older event at ~340 Ma (Fornos and Fonte Santa granites), predating the onset of C3 deformation and likely associated with late C1 crustal thickening to early C2 tectonics, and a younger pulse at ~320–318 Ma (Carviçais and Bruçó granites). These magmatic pulses are linked to contrasting structural controls, with the older granites emplaced within regional-scale antiforms and the younger intrusions localised along structures related to C3 deformation. Together, these results document two discrete crustal melting events separated by ~20 Ma and record a progressive shift from fold-controlled to strike-slip-dominated granite emplacement during Variscan orogenic evolution. Moreover, the study highlights that tungsten mineralisation is preferentially associated with reduced, crust-derived granites emplaced during specific tectonic regimes, providing new constraints for metallogenic models in NW Iberia. Full article

The Middle Tonian tectonic setting of the Jiangnan Orogen, South China, remains intensely debated, and is centered on two competing models: subduction–collision versus mantle plume. This study addresses this critical knowledge gap through an integrated, multi-proxy investigation of the Middle Tonian Fanjingshan Group. This region preserves a continuous volcano-sedimentary and magmatic record, offering key insights into the orogen’s full lifecycle. To test these hypotheses, we employed a synthesis of geological survey, sediment provenance analysis, detrital zircon U-Pb geochronology of clastic rocks to determine sediment provenance and basin evolution, and petrogenetic study of coeval magmatic suites (pillow lava, mafic–ultramafic sills, and granitoids) to evaluate their magmatic processes and tectonic setting. Analysis of 1736 detrital zircon U-Pb ages from Middle Tonian strata reveals a four-stage provenance evolution: (1) SW Yangtze sources in a passive margin basin before 870 Ma; (2) bidirectional sources in an 870–835 Ma arc-derived basin; (3) syn-collisional detritus during 835–820 Ma amalgamation; and (4) post-collisional and northern Yangtze inputs in an 800 Ma rifting basin. Geochemical data from ~845–840 Ma basalts and coeval sills reveal calc-alkaline affinities and marked subduction-fluid signatures. Their calculated mantle potential temperature (1404 °C) is significantly lower than that expected for plume-derived melts (1570 °C), which is consistent with melting in a subduction-modified mantle wedge, supporting a continental rear-arc basin setting. The ~845–832 Ma mafic–ultramafic sills exhibit symmetrical geochemical zoning and two-stage emplacement, recording sustained magma recharge in the rear-arc basin. Furthermore, the ~830 Ma Fanjingshan granite is identified as a crust-derived, syn-collisional S-type granite. Synthesizing these findings, we demonstrate that the sedimentary and magmatic records collectively point to plate margin setting. A four-stage tectonic model is suggested: (1) pre-870 Ma passive margin without significant magmatic activity; (2) 870–835 Ma continental arc development at an active continental margin; (3) 835–820 Ma Yangtze–Cathaysia collision; and (4) post-820 Ma post-orogenic rifting. This work provides a robust regional case study, demonstrating that integrating records of deep magmatic processes with coeval shifts in sedimentary provenance and basin architecture is essential to reconstruct the complete evolution of ancient orogens. Full article

In recent decades, ion-adsorption-type rare earth element (iREE) deposits have been widely documented in the weathering crusts of granitic and volcanic rocks and their geological characteristics and genetic mechanisms extensively studied. Ion-adsorption-type REE mineralization was documented for the first time in the weathered crust overlying the epimetamorphic rocks in Ningdu County, China. In contrast to well-documented granite-derived weathering profiles, investigations of epimetamorphic rocks as protoliths for such REE deposits remain limited, particularly regarding the mineralogy of REE-bearing phases and the geochronology and geochemistry of their parent rocks. To address this gap, the present study combines comprehensive petrographic and mineralogical analyses of REE-mineralized Shenshan Formation phyllites with the U–Pb dating of zircon and apatite and trace element geochemical investigations. U–Pb zircon and apatite geochronology yields a protolith age of ca. 785 Ma for Shenshan Formation metamorphic rocks, consistent with mid-Neoproterozoic magmatism. REE-bearing minerals in the Shenshan Formation phyllites comprise allanite-(Ce), apatite, cerianite-(Ce), monazite-(Ce), rhabdophane-(La), rutile, Y-bearing thorianite and xenotime-(Y). Among these, apatite is the most abundant and likely the principal source of ionic REEs in the deposit. Ti-in-zircon thermometry indicates crystallization temperatures of 641–749 °C (mean ~704 °C), reflecting a prolonged magmatic–hydrothermal evolution. This extended history chiefly controlled the differentiation and redistribution of rare earth elements (REEs), thus governing their availability for subsequent supergene enrichment. Zircon-based oxygen fugacity (fO₂) estimates a range from −31.4 to −9.9 (mean −17.9), consistent with reduced magmatic conditions. Trace element correlation diagrams for zircon and apatite indicate that the intrusion underwent an extensive fractional crystallization of accessory phases (zircon, monazite, apatite, titanite, rutile) and plagioclase. The distribution patterns of trace elements further suggest that the Shenshan Formation protolith formed in a continental margin arc or arc-related orogenic belt setting, with geochemical signatures characteristic of an S-type granite. The Shenshan Formation phyllites in southern Jiangxi exhibit high REE abundances and host a labile assemblage of weatherable REE-bearing minerals, providing an optimal material framework for ion-adsorption-type REE deposits and indicating substantial mineralization potential. Full article

The Guanfang tungsten deposit in the Bozhushan ore district, southeastern Yunnan, is genetically linked to Late Yanshanian granitic intrusions. To elucidate the petrogenesis and mineralization potential of the causative granite, this study presents a detailed mineral chemical analysis of biotite from the Guanfang pluton using electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The biotite crystals exhibit relatively high euhedrality, show no obvious alteration features, and are chemically characterized by reduced Na and Ca contents. These features, along with petrographic observations, confirm its origin as primary magmatic biotite. Crystallization conditions, calculated from biotite chemistry, indicate temperatures of 700–720 °C and pressures of 1.22–1.73 kbar, corresponding to a mesozonal emplacement depth of 4.6–6.5 km. Oxygen fugacity estimates, plotting near the Ni-NiO buffer, reveal an oxidized magmatic environment. Geochemical discrimination diagrams suggest the Guanfang granite exhibits transitional features between S-type and I-type affinities and is classified as a syn-melting (high-temperature) type. The biotite contains relatively low F (0.71–0.97 wt%), but elevated Cl (0.13–0.20 wt%) and Sn (43–56 µg/g) contents. This specific geochemical signature—combined with the medium- to high-temperature crystallization setting—is highly favorable for W-Sn mineralization. Furthermore, the high-Ti, syn-melting character of the granite implies additional potential for Cu-Pb-Zn-Au-Ag polymetallic mineralization. This study employs biotite chemistry to assess the petrogenesis and metallogenic potential of the Guanfang granite. The subsequent discovery of industrial ore bodies corresponding to some of the elements identified as having metallogenic potential confirms the feasibility of this approach. Accordingly, this method provides a new tool for future exploration in the Bozhushan district. Full article

The origin of Mesozoic granites associated with the Dahutang W-Cu-Mo orefield in northern Jiangxi, which hosts the world’s second-largest tungsten deposit, remains a compelling subject despite extensive geochemical and geochronological studies. In this contribution, we present wolframite mineral and whole-rock geochemistry, as well as monazite and zircon U-Pb ages, for the Mesozoic granites to constrain our understanding of the petrogenesis of these granites and their coupling relationship with the mineralization. The following two magmatic phases and four types of rocks in the study area are identified: the early stage (152–147 Ma) biotite (G1) granites and the late stage (144–130 Ma) two-mica (G2),muscovite (G3), and albite (G4) granite series. These two magmatic phases are temporally coincident with two mineralization stages (~150 Ma and 144–139 Ma). All the Mesozoic granites share the characteristics of high silica content, peraluminosity (A/CNK > 1.1), and low Zr + Nb + Ce + Y values (<200 ppm); they are derived from the partial melting of a Proterozoic crustal source and classified as S-type granites. Specifically, the G1 granites are characterized by relatively high MgO (~0.5%), CaO (~1%), and low P₂O₅ (0.13%–0.20%). They formed through a relatively high degree of partial melting at approximately 766 °C (zircon saturation temperatures), a process influenced by biotite dehydration reactions, with minor contributions from mantle-derived materials. In contrast, the G2–G4 granite series exhibits more typical peraluminous S-type granite features, such as high Al₂O₃, Na₂O, and P₂O₅ (mostly > 0.2%) contents, and low Sr and Ba contents. They are products of low-degree partial melting that occurred under conditions close to muscovite breakdown at ~726 °C. Additionally, fluid–melt interaction is recorded in both granites by distinctive geochemical signatures, including enrichment in Sn (>30 ppm), Cs (>35 ppm), Li (>250 ppm), F (>0.4%), and W (10–1000 ppm), coupled with low K/Rb (<150) and Nb/Ta (<5) ratios. The near-chondritic Zr/Hf (22.6–34.1) and Y/Ho (24.5–31.5) ratios of the G1 granites imply a relatively limited role of magmatic fluid–melt interaction during its evolution. For the G2–G4 granites, however, intense crystal fractionation and late-stage fluid–melt interaction are well-documented by their highly variable and low ratios of Y/Ho (14.8–41.4), Nb/Ta (0.89–5.57), Zr/Hf (8.84–41.67), and K/Rb (13.96–128.29). In the long-lived, reduced, and volatile-rich aqueous environment of the G2–G4 magmas, fractional crystallization and albitization collectively enhanced the solubility and hydrothermal transport capacity of W, Sn, Li, Nb, and Ta by multiple orders of magnitude. In contrast, in the earlier, more oxidized G1 magmas (which incorporated mantle materials), the exsolution and hydrothermal transport of Cu and Mo were associated with localized greisenization, but their capacity diminished with fractional crystallization. Historically, mineral exploration in the Dahutang mining area has focused primarily on W, Cu, and Mo. Based on this research, we conclude that there is significant mineral potential for rare metals (particularly Sn, Li, and Ta), and future exploration should prioritize areas adjacent to the evolved G2–G4 peraluminous leucogranites to search for new concealed mineral occurrences. Full article

The stability of deep water-saturated rock masses under dynamic disturbance is crucial for the efficient development of deep geothermal resources. This study focuses on granite as the research object, using the Split Hopkinson Pressure Bar (SHPB) system to investigate the dynamic mechanical properties, energy dissipation, and failure characteristics of dry and saturated granite under impact loading, and to analyze the influence of water on the dynamic mechanical properties of granite. The results show that granite exhibits a Type II stress–strain curve (rebound phenomenon) at low strain rates, while at high strain rates, it exhibits a Type I stress–strain curve. The dynamic mechanical parameters of granite exhibit significant strain rate dependence, with water-saturated granite showing a stronger strain rate sensitivity. The dissipated energy and dissipation coefficient of the granite samples increase linearly and logarithmically, respectively, with the increase in incident energy. The dissipated energy of water-saturated granite is higher than that of dry granite. As the strain rate increases, the failure mode of the granite specimens transitions from splitting to fragmentation, with a more pronounced ductile fracture mode. The degree of fragmentation of water-saturated specimens is greater than that of dry specimens. As the strain rate increases, the difference in fractal dimensions between dry and water-saturated specimens decreases. At high strain rates, the free water within the rock generates inertial effects, meniscus effects, and viscous effects. When the strain rate reaches 124.22 s⁻¹, the strength of the water-saturated specimen matches that of the dry specimen. The research findings provide theoretical support for the safe and efficient development of deep geothermal resources. Full article

The Tawenchahanxi mining area, situated in the southeastern Qimantagh region of the East Kunlun Orogenic Belt, hosts a skarn-type Fe–polymetallic deposit associated with acidic granitic intrusions. Laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb dating yields ages of 233.3 ± 1.2 to 234.3 ± 1.1 Ma for a granodiorite and 397.7 ± 1.4 Ma for a quartz porphyry, indicating two magmatic intrusive events during the Early Devonian and Late Triassic. The Early Devonian quartz porphyry is characterized by high ${\mathrm{S}\mathrm{i}\mathrm{O}}_2$ (72.39%–74.04%), high total alkalis (7.81%–7.83%), high TFeO (>1.0%) and high crystallization temperatures (~865 °C), together with low CaO (1.64%–1.70%) and MgO (0.61–0.65%), which are all consistent with A-type granite affinity. The granodiorite exhibits aluminum saturation index (A/CNK) values of 0.67–1.07 (metaluminous to weakly peraluminous) and belongs to the high-K calc-alkaline series. It exhibits moderate negative Eu anomalies (δEu = 0.71–0.83), and zircon saturation temperatures of ~748 °C, collectively indicative of I-type granite affinity. Both rock suites display depletion in Nb, Ta, and Sr and enrichment in Rb and LREEs. Zircon Hf isotopic data show εHf(t) values of −0.64 to 0.57 for the quartz porphyry and −4.37 to −1.06 for the granodiorite, indicating derivation primarily from partial melting of ancient crust with variable mantle contributions. These intrusions formed during post-collisional extensional (Early Paleozoic) and collisional to post-collisional (Late Paleozoic–Early Mesozoic) stages, respectively, associated with mantle magma underplating and crust–mantle mixing. Such processes formed the material basis for the polymetallic mineralization in the Tawenchahanxi district by providing Fe–Cu–Pb–Zn and other ore-forming elements from deeper crust. Full article

This study investigates the complex relationship between fracture patterns and acoustic emission (AE) mechanisms during triaxial deformation experiments on Westerly granite under various confining pressures (5, 10, 20, and 40 MPa). Using numerical simulations with the Particle Flow Code (PFC2D, 6.0, Itasca Consulting Group Inc., Minneapolis, MN, USA), this research emphasizes the significant influence of confining pressure on crack development, AE events, spatiotemporal distribution, energy dissipation, and peak stress in the samples. AE source mechanisms, categorized into T-Type, C-Type, and S-Type, show the dominance of T-Type fractures during post-peak unstable failure and the emergence of C-Type fractures as precursors to critical damage. Additionally, increasing confining pressure is found to correlate with changes in fracture dynamics, evidenced by an increase in big events and a decrease in small events. The analysis of b-values across different pressures reveals fluctuations that indicate change in fracture features. Fractures originate in the model center and propagate towards both ends as loading progresses, ultimately leading to failure. In summary, these findings provide important insights into the fracture patterns of granite and the underlying mechanisms of AE release. Moreover, they carry practical implications for identifying failure precursors and for the potential application of early warning systems in rock engineering. Full article

The Bagenheigqier medium-sized Pb-Zn deposit is located in central-southern segment of Great Xing’an Range, northeastern China, where its vein-type orebodies are hosted within the structural contact zone between the Lower Permian Dashi Formation and granite porphyry intrusions. Five mineralization stages are divided into skarn (I), oxide (II), quartz-pyrite-arsenopyrite (III), quartz-polymetallic sulfide (IV), and quartz-calcite-pyrite (V). Three types of fluid inclusions (FIs) are identified in Bagenheigeqier Pb-Zn deposit, including daughter mineral-bearing three-phase (SL-type), vapor–liquid two-phase (VL-type), and vapor-rich two-phase (LV-type) FIs. All FI types occur in Stages I–III, with homogenization temperatures (Th) of 423–486, 389–441, 362–408 °C, and salinities of 1.1–49.2, 0.9–43.9 and 0.9–38.8 wt.% NaCl equiv, respectively. Stage IV hosts only VL- and LV-type FIs (Th: 277–319 °C; salinity: 2.1–8.7 wt.% NaCl equiv), whereas Stage V contains exclusively VL-type FIs with Th of 173–214 °C and salinity of 1.2–5.7 wt.% NaCl equiv. The H-O isotopic results of quartz in stage II–IV (δD = −103.5‰–−99.1‰, −115.7‰–−107.8‰ and −121.5‰–−117.2‰; δ¹⁸O_H2O = 4.4‰–7.1‰, 1.1‰–3.5‰ and −4.6‰–−3.5‰) indicate the ore-forming fluids are predominantly of magmatic origin with subordinate meteoric water mixing. Fluid boiling and the mixing of meteoric water may lead to the precipitation of metal. The in situ trace elements analyses indicate that sphalerites in main mineralization stage are enriched in Fe, Mn, Co and In and depleted in Ga and Ge. The calculation results suggest that the sphalerites crystallized under moderate temperature conditions (286–330 °C) and intermediate f_S2 (−10.5 to −9.2) conditions. The geological, fluid inclusion, isotopic and trace element evidences indicate that the Bagenheigeqier deposit is classified as a skarn-type deposit. Full article

The Himalayan metallogenic belt is a globally significant province for leucogranites and pegmatites. Recent exploration has yielded major breakthroughs in the exploration of pegmatite-type Li-Be-Nb-Ta rare-metal deposits within its eastern segment. Discoveries such as the Qiongjiagang and Lhozhag deposits underscore the region’s substantial mineralization potential. In contrast, the western Himalayan segment remains comparatively underexplored. This study presents the geology and geochronology of the newly identified Zhaguopu Li-Be-Nb-Ta deposit in the Gyirong area, providing critical new insights. The deposit is centered on the Gyirong granite dome, which features a core of tourmaline-bearing leucogranite surrounded by a peripheral zone of beryl-bearing pegmatites and vein- to lens-shaped spodumene pegmatites, all hosted within metamorphosed sandstone, slate, and marble. The largest individual spodumene pegmatite vein exceeds 400 m in length, with thicknesses ranging from 0.5 to 4 m and a cumulative thickness surpassing 50 m. Principal ore minerals include spodumene, beryl, and columbite-group minerals. U-Pb geochronology of zircon, monazite, and columbite-group minerals from the leucogranite and pegmatite units constrains the rare-metal mineralization to a tight interval of 25–23 Ma, contemporaneous with the Qiongjiagang and Lhozhag deposits. Whole-rock geochemical data define a coherent fractional crystallization sequence from tourmaline granite through beryl pegmatite to spodumene pegmatite, characterized by increasing SiO₂ and peraluminosity, and extreme depletion in Ba, Sr, Eu and Nb/Ta ratios. This geochemical trend underscores the critical role of extreme magmatic differentiation in rare-metal enrichment. Field relationships and these coeval ages strongly support a genetic model in which the mineralized pegmatites originated from the extreme fractional crystallization of a common, cogenetic magmatic suite. The timing of this mineralization event correlates precisely with the post-collisional extension of the Himalayan orogen and the activity of the Southern Tibet Detachment System. We conclude that the interplay between this large-scale tectonism and magmatic differentiation is the fundamental driver for rare-metal enrichment. The discovery of the Zhaguopu deposit highlights the significant and previously underestimated potential for major pegmatite-type rare-metal deposits in the western Himalayan belt. Full article

Reducing the environmental impact of road transport requires pavements that contribute to lower fuel consumption of vehicles and greenhouse gas emissions throughout their life cycle. Rolling resistance plays a key role in this context, while warm mix asphalt (WMA) technologies offer additional benefits by reducing energy use and emissions during production and construction. This study investigates the combined influence of aggregate type and aggregate gradation on the rolling resistance and functional performance of WMA wearing course mixtures. Ten laboratory-produced mixtures were designed, including dense-graded asphalt concrete (AC 11 VS) and stone mastic asphalt (SMA 8 S) with granite or dolomite aggregates, produced at reduced temperatures using a chemical WMA additive and polymer-modified bitumen PMB 45/80-65. Rolling resistance was evaluated using a laboratory energy loss method with two different tyres, along with assessments of volumetric properties, moisture resistance, surface macrotexture, and resistance to scuffing. The results indicate that aggregate gradation is the primary factor governing rolling resistance, and dense-graded mixtures exhibit lower energy loss due to their smoother surface texture. The aggregate type showed a secondary but consistent effect, with granite mixtures generally demonstrating slightly lower rolling resistance and improved resistance to surface degradation. In general, the findings confirm that WMA technologies can be effectively integrated into low-rolling-resistance asphalt mixtures, achieving reduced rolling resistance without compromising durability and thus supporting energy-efficient and sustainable pavement solutions. Full article

During the magmatic stage, base and rarer metals segregate from silicate melts to form ore deposits. The usual case is the porphyry (PD) type (Cu, Mo, and W) above subduction zones. The metal grade increases from some ppb or ppm up to percent levels. A new type of trans-porphyry (TPD) deposits (Sn, Ta, Nb, and gems) results from large-scale shear between cratons within continental plates, internal decoupling, and vertical motion. The bulk ore generation process develops along three stages: from magma generation, emplacement, and the formation of an immiscible magmatic phase (MIP), fluids, and melt. However, in TPD, metals segregate from the crust during melting below 800 °C, biotites break down, and the melt remains below the critical point (731 °C). Fluid advection competes with chemical diffusion, yielding the required enrichment. The subcritical MIP splits into a silicate-rich and an aqueous-rich phase, which are both incompatible with each other. Granite, pegmatites, and greisen coexist in the magma chamber. Their respective extraction from a composite mush involves electron exchanges between charges, or orbitals, yielding metal oxides through chemical diffusion. In contrast, in metals (Nb and Ta) observed in pegmatites, and also in gems, electrons rearrange their electronic cloud through their polarizability. Lastly, gems independently grow under the influence of the extremely hard fluids (Li, Be, and B). Magma generation, involving the lower crust (garnet and pyroxene), results in melts that form the two observed pegmatite groups (NYF and LCT), with each being associated with alkaline (A-type) or continental (S-type) granitic melts. Full article

Recent discoveries of fluorite–barite deposits in the Donghai–Linshu area in northern Jiangsu Province, China, underscore the region’s mineral potential, yet detailed geological investigations remain limited. In this study, we examined monzonite and quartz monzonite from drill cores in the Jiashan mining area using petrography, U–Pb zircon dating, zircon trace element geochemistry, whole-rock geochemistry, and zircon Lu–Hf isotopes. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) zircon U–Pb analyses were conducted to constrain the crystallization ages of the monzonite (127.06 ± 0.54 Ma and 126.83 ± 0.75 Ma) and quartz monzonite (127.2 ± 0.5 Ma and 128.59 ± 0.62 Ma) to the Early Cretaceous, marking a significant magmatic event. Many of the zircons contain inherited Neoproterozoic cores (718–760 Ma and 800–860 Ma), indicating the assimilation of deep crustal materials of this age. The monzonite is metaluminous, with moderate SiO₂ (61.61–62.41 wt.%), high alkalis (Na₂O + K₂O = 7.48–7.92 wt.%), and A/CNK = 0.72–0.91. The quartz monzonite has higher SiO₂ (66.26–68.18 wt.%) and alkalis (8.32–9.33 wt.%). Both rock types exhibit similar trace and rare earth element patterns: enrichment in large-ion lithophile and light rare earth elements, depletions in Nb, Ta, and Ti, no significant Zr-Hf depletion, and weak negative Eu anomalies (δEu ≈ 0.84–1.00). Their low Zr + Nb + Ce + Y contents, Ga/Al ratios, and TFeO/MgO ratios indicate that they have an I-type granite affinity. The Early Cretaceous zircons have highly negative ε_Hf(t) values (−33.7 to −23.5) and ancient two-stage model ages (2622–3247 Ma), which are consistent with derivation from Archean crust. The inherited Neoproterozoic zircons have younger Paleo–Mesoproterozoic T_DM2 ages. The evidence suggests that both intrusions were mainly generated by partial melting of ancient Archean basement, with minor mantle input. The magma generation was likely triggered by crustal anatexis induced by the underplating of mantle-derived magmas in an extensional tectonic regime, coeval with Early Cretaceous magmatism in the Sulu orogen. Full article