Layered Intrusions Research Articles

Construction of hydrogel interlayer and nanovoid to develop NF membranes with good antifouling property and permeability

Membrane fouling in water treatment impacts the efficiency and lifetime of nanofiltration (NF) membranes. Between the polyvinylidene fluoride (PVDF) substrate and the polyamide (PA) layer, sodium alginate (SA) hydrogel interlayers were introduced in this study. Subsequently, nano-CaCO3 was deposited on the SA hydrogel interlayers membrane (PA-Alg membrane), encapsulated within the membrane using the interfacial polymerization (IP), and dissolved with acid to form nanovoids. Thus, NF membranes with excellent antifouling property and high permeability were fabricated. The SA hydrogel interlayers and the deposition and dissolution of nano-CaCO3 were verified by X-ray photoelectron spectroscopy and Fourier transform infrared. A smooth membrane surface was observed using scanning electron microscopy and atomic force microscopy. The flux of the SA hydrogel interlayers and nanovoids (PA-Alg-NV) membrane was 86% greater than that of the pristine membrane. The rejection values of the PA-Alg-NV membrane for MgSO4 and MgCl2 were 95.6% and 95.1%, respectively. The flux recovery ratio for humic acid, bovine serum albumin, oil/water emulsion, and SA through PA-Alg-NV membrane were 97.2%, 97.3%, 97.4%, and 97.9%, respectively. Long-term fouling tests and ten-cycle fouling tests indicated that the PA-Alg-NV membrane exhibited stable antifouling property. In general, the high permeability and excellent antifouling property of the PA-Alg-NV membrane were attributed to the SA hydrogel interlayers, which increased hydrophilicity and reduced PA layer intrusion into the pores, forming a thin and smooth surface. In addition, the permeability was further enhanced by the nanovoids within the membrane. This study presented an efficient approach for fabricating NF membranes with excellent antifouling property and high permeability.

Fe-isotopic evidence for hydrothermal reworking as a mechanism to form high-grade Fe-Ti-V oxide ores in layered intrusions

The genesis of high-grade Fe-Ti-V oxide ores (up to >90 vol%) in layered intrusions remains highly debated. Here, on example of Hongge layered intrusion in China, we show that hydrothermal dissolution and precipitation of Fe-Ti-V oxides played a critical role in forming high-grade massive ore deposits as demonstrated by textural-compositional evidence and in-situ iron isotope data (δ56Fe), analyzed with femtosecond laser ablation multicollector (LA-MC-) ICP-MS. Hongge is a mafic layered intrusion composed of a Lower olivine clinopyroxenite Zone (LZ), a Middle clinopyroxenite Zone (MZ), where thick massive ore layers (with up to 90 % Fe-Ti-V oxides) formed, and an Upper gabbro Zone (UZ). Magnetite in Hongge exhibits two contrasting generations: 1) Mag1, observed in all lithological zones and formed at the magmatic stage, has extensive ilmenite exsolution lamellae and high Ti and Cr content. The δ56Fe of Mag1 shows considerable variations from −0.23 to 0.63 ‰ and strikingly an offset of ∼0.3 ‰ towards lower values in the massive ore zone compared to the zones below and above; 2) Mag2, concentrated mainly in thick massive ore layers in MZ without exsolution lamellae, is almost pure magnetite (with low Ti, Al content) and has extremely low δ56Fe values (−1.24 to −0.09 ‰), indicating precipitation from Fe-enriched hydrothermal fluids. Similarly, the δ56Fe of ilmenite shows significant variations from −1.08 to −0.27 ‰ and is significantly lower than typical values for igneous ilmenite (−0.4–0 ‰). Ilmenite displays a similar Fe isotope variation pattern to Mag1 along the stratigraphic position, i.e., with significantly lower δ56Fe in the massive ore zone. As magnetite and ilmenite together contain essentially all Fe, the isotopic shift of these minerals in the ore zone translates to a bulk isotopic offset of ∼−0.3 ‰ compared to the zones below and above. This requires a bulk flux of isotopically light Fe resulting in Fe enrichment in this zone to form massive or even monomineralic ores. The very light isotopic values, particularly hydrothermal magnetite (Mag2) and petrologic evidence, strongly indicate that the Fe flux into the massive ore layers occurred during hydrothermal reworking. This scenario is furthermore supported by magnetite-ilmenite elemental and isotopic thermometry, according to which Fe-Ti oxides experienced hydrothermal re-equilibration in a temperature range of 400–300 °C. Iron isotopic mass balance calculations imply that ∼20–30 % of the Fe in the thick massive ore layers may result from secondary enrichment through hydrothermal precipitation, significantly increasing the ore tonnages and grades. Potentially, other layered intrusions experienced similar mechanisms of hydrothermal Fe enrichment, which will have to be proven in future investigations.

Comprehensive Survey of Web Security Threats in 2024

In recent years, the landscape of web security threats has evolved rapidly, driven by advancements in technology and increasingly sophisticated attack vectors. This paper presents a comprehensive survey of prominent web security threats in 2024, examining both traditional vulnerabilities and emerging risks that have intensified in the digital environment. We explore a range of threats, including but not limited to application-layer attacks, network- layer intrusions, and data privacy concerns. The study draws upon a wealth of sources, including industry reports, academic research, and standards from leading organizations. Our findings underscore the critical need for web application developers, security professionals, and organizations to adopt proactive defense mechanisms and stay informed on current threats to effectively protect web-based assets. This survey aims to serve as a reference for security practitioners and researchers, highlighting essential vulnerabilities and encouraging further exploration of effective countermeasures. Keywords Web Security, Threat Detection, Data Privacy, Cross-Site Scripting (XSS), SQL Injection, DDoS Attacks, Zero-Trust Architecture, Quantum-Resistant Encryption, Cloud Security, Machine Learning in Security

Petrogenetic relationship of the variably Ni−Cu−platinum-group element (PGE)-mineralized intrusions of the Thunder Bay North Intrusive Complex, Midcontinent Rift, Canada: Implications for mineral exploration in mafic−ultramafic complexes

The Thunder Bay North Intrusive Complex (TBNIC) of Canada comprises six variably Ni−Cu−platinum-group element (PGE)-mineralized mafic−ultramafic intrusions that intruded the Archean Quetico Subprovince. These are the Current, Escape, Lone Island, Greenwich, and 025 intrusions, with the former three aligned along an east−west-trending intrusion termed the East−West Corridor. These intrusions have a consistent igneous stratigraphy comprising, from bottom to top, peridotite, gabbros, and quartz gabbro. Only the Current and Escape intrusions are known to host sulfide mineralization in the peridotite. Despite the economic significance of the TBNIC, little work has been done to characterize its petrogenetic evolution and the causes of the apparent variable fertility. Our new ages for Escape (1107.6 ± 0.9 Ma) and Greenwich (1105.7 ± 0.9 Ma), combined with previously determined ages for Current (1106.6 ± 1.6 Ma) and Lone Island (1106.3 ± 2.1 Ma), demonstrate that the TBNIC was emplaced as part of the ca. 1.1 Ga Midcontinent Rift event. The similarities in their rare earth element geochemistry and consistently low Th/La−Sri values indicate that the intrusions crystallized from genetically related magmas that did not assimilate significant amounts of crustal material. Accordingly, their systematically negative εNdt values and Nb anomalies likely reflect that their parent magmas were largely sourced from the subdcontinental lithospheric mantle and not the Keweenaw Plume. Given their genetic relationship, the variable fertility of the intrusions cannot be related to processes that occurred in their mantle sources. Since the gabbros have systematically depleted Cu/Zr−Cu/Pd ratios and the peridotites have enriched ratios, the apparent variable fertility is likely related to the timing and location of sulfide segregation and accumulation, with the barren gabbros preserving magmas that lost sulfide liquid during transport to shallow crustal levels, and the mineralized peridotites recording accumulation of sulfide liquid. This interpretation has important implications for exploration as it implies that sulfide mineralization in the apparently barren intrusions may be located at depth in undiscovered ultramafic cumulates.

Clinopyroxenite-Wehrlite Porya Guba Complex with Fe-Ti-V and PGE-Cu-Ni Mineralization in the Northeastern Part of the Fennoscandian Shield: Evidence of Post-Orogenic Formation from Sm-Nd Isotope System

The Porya Guba clinopyroxenite–wehrlite complex is located in the core of the Lapland–Kola collisional orogen (~2.0–1.9 billion years old) in the northeastern part of the Fennoscandian Shield and contains iron–titanium–vanadium and nickel–copper mineralization with platinum group elements (PGEs). The controversial geological position of the complex within the mafic granulites of the Kolvitsa mélange (pre-, syn- or post-orogenic) is clarified by Sm-Nd isotopic dating of the rocks and mineralization. The Sm-Nd age of the barren clinopyroxenites that dominate the complex is 1858 ± 34 Ma (εNd(T) = −1.5) and is interpreted as the time of its emplacement as evidenced by a sample from the largest intrusion, named Zhelezny. This age is younger than that of the peak of granulite metamorphism in the host rocks (1925–1915 Ma) and coincides within error with the age of rutile from granulites (1880–1870 Ma), indicating the time at which cooling to 450 °C occurs. Emplacement in the cooled rocks is confirmed by the detection of quenching zones in clinopyroxenites around granulite xenoliths. Magnetite ores, as well as mineralized pyroxenites with sulfide disseminations, are formed during a late stage of the complex development, as suggested by active assimilation of granulite xenoliths by these rocks. The isotopic age of mineralized pyroxenites enriched in PGEs is 1832 ± 35 Ma (εNd(T) = –2.0), while the age of magnetite ores is 1823 ± 19 Ma (εNd(T) = –2.5). Thus, the obtained isotopic data indicate that the emplacement of the Porya Guba complex and probably other small mafic–ultramafic intrusions in the Kolvitsa mélange granulites took place after the end of the Lapland–Kola collision.

A New Crustal Thickness and VP/VS Model of the Indochina Peninsula

Abstract The Indochina peninsula is formed by the collision of continental terranes, magmatic arcs, and suture zones due to the closure of the Palaeo-Tethys oceans during the Mesozoic and has experienced complex tectonic activities during the Cenozoic. Crustal thickness and VP/VS of the peninsula can help better understand its tectonics and formation, so we generate a new high-precision crust model for this region via the receiver function H−κ stacking method. The Khorat plateau has thicker crust (∼36.3 km) than other regions (∼32.4 km), whereas the elevation is similar (<500 m) or even lower. The poor correlation between crustal thickness and elevation suggests that there are other factors controlling the Khorat plateau elevation, for example, negative buoyancy of the lithosphere mantle. High crustal VP/VS (1.79–1.83) observed in southern Khorat plateau and southeastern Indochina Terrane indicates a mafic crustal composition that is consistent with extensive Late Cenozoic basaltic volcanism. Furthermore, our new model reveals high crustal VP/VS (1.81–1.95) in the east of the Nan suture and north of Khorat plateau, which could be interpreted as mafic–ultramafic intrusions in the continental back-arc basin east of the Sukhothai arc in the Late Palaeozoic. Our model does not support the existence of the eastward branch of the midlower crustal flow of the Tibetan plateau because a crustal weak layer would be too thin or too dispersed to flow.

Geochemical and Sr-Nd isotopic implications for the petrogenesis of the late Silurian Shitoukengde mafic–ultramafic intrusion in the East Kunlun Orogen, NW China

The Shitoukengde mafic–ultramafic intrusion is the host of the second-largest sulfide deposit after the Xiarihamu Ni-Co deposit in the East Kunlun Orogenic Belt (EKOB), northern Tibet Plateau, China. Despite several studies, the age, petrogenesis, and the cause of low Ni-tenor for this intrusion remain poorly constrained. In this study, zircons separated from the pyroxenite at Shitoukengde yield a SHRIMP U-Pb age of 418.9 ± 3.1 Ma, corresponding to the widespread magmatism of the late Silurian to early Devonian in the EKOB. Whole-rock major and trace element compositions indicate that fractional crystallization played a key role in controlling the magma composition and element distribution within the intrusion. Mafic-ultramafic rocks of the intrusion, particularly peridotite, have highly variable and exceptionally elevated (87Sr/86Sr)i and negative ɛNd(t) values. Some samples from the Shitoukengde intrusion exhibit initial Sr-Nd isotope ratios that overlap with those from the Xiarihamu intrusion, while others (e.g., peridotite) display higher (87Sr/86Sr)i values than those observed in the latter. The unusual Sr-Nd isotopic compositions of the Shitoukengde intrusion could be attributed to the assimilation of Mg-rich carbonate within a deep-seated magma chamber. This contamination process facilitates the crystallization of olivine, consequently reducing Ni content in residual magma. Furthermore, the contamination of Mg-rich carbonate may promote oxygen fugacity and thus enhance the solubility of sulfur while restricting the sulfide saturation in the magma. We thus propose that the extensive contamination of Mg-rich carbonate is a key factor contributing to the relatively low Ni-tenor observed at Shitoukengde.

Mechanisms of Co enrichment in the Zhubu Ni–Co–PGE deposit in the Emeishan LIP, SW China: Constraints from mineral geochemistry and Fe–S isotopes of sulfides

The Zhubu Ni–Co–PGE sulfide deposit in the Permian Emeishan Large Igneous Province (LIP), SW China is hosted by a mafic–ultramafic intrusion that comprises two morphologically distinct ore-forming spaces: a central, layered sequence that represents a magma chamber surrounded by a marginal sub-vertical conduit zone. The marginal conduit zone contains significant Ni–Co–PGE sulfide mineralization, suggesting that high volumes of sulfide-bearing silicate melt flowed through the magma conduit system. Determining the hosts of Co is key to understanding the Co enrichment process in the Zhubu deposit, as well as in the Emeishan LIP as a whole. We assess this here using the geochemistry and Fe–S isotope compositions of sulfides in the Zhubu deposit. Cobalt is mainly concentrated in pentlandite sulfide in the websterite, with Co contents increasing in the order pyrrhotite < chalcopyrite < pyrite < pentlandite < violarite; the abundance of violarite, however, is notably lower than that of the other sulfides. The Co contents of pentlandite, pyrite, and chalcopyrite are negatively correlated with their Ni and Fe contents, suggesting that Co substitutes isomorphically for Ni and Fe in the sulfide structure. The δ56Fe values of sulfides increase in the order pyrrhotite < chalcopyrite < pentlandite < pyrite resulted from kinetic fractionation of Fe isotopes. The δ56Fe values of pentlandite and chalcopyrite in lherzolite are higher than those in websterite, implying that lherzolite and websterite formed in compositionally distinct magmas, Fe isotope compositions become heavier with crystal fractionation. The δ34S values of sulfides increase in the order pyrrhotite < pentlandite < chalcopyrite < pyrite, similar to the fractionation sequence of sulfide melts, suggesting that externally derived S was added to the magma and contributed to its sulfide saturation. The Co contents of chalcopyrite and pyrite vary positively with δ56Fe values, and negatively with δ34S values, indicating that the addition of externally derived S and resulting sulfide segregation were critical to Co enrichment.

Revisiting magnesium isotope constraints on the petrogenesis of the Fe-Ti oxide-bearing mafic–ultramafic intrusions

Stable isotopes of metals, such as magnesium (Mg) and iron (Fe), typically undergo minimal fractionation at magmatic temperatures. However, in Fe-Ti oxide-bearing intrusions, significant Mg isotope fractionation (Δ26Mg values of up to 23 ‰) has been observed between silicates and Fe-Ti oxides. The mechanism responsible for this substantial fractionation remains unclear. This study presents Mg isotopic compositions for bulk rocks and mineral separates—including olivine, clinopyroxene, titanomagnetite, ilmenite—from sixteen Fe-Ti oxide ores in both the lower and the upper zones of the Baima layered mafic–ultramafic intrusion, as well as bulk rocks from three high-Ti basalts of the Emeishan large igneous province, SW China. Oxide ores from the lower zone and the lower section of the upper zone of the Baima intrusion are characterized by a low abundance of volatile-bearing minerals, such as apatite and hornblende. These ores exhibit δ26Mg values ranging from −0.30 to −0.14 ‰ for olivine, −0.26 to −0.06 ‰ for clinopyroxene, 0.16 to 0.60 ‰ for titanomagnetite and −0.33 to −0.21 ‰ for ilmenite, indicative of near-equilibrium fractionation. In contrast, oxide ores from the upper section of the upper zone exhibit a high abundance of volatile-bearing minerals and significantly different δ26Mg values, ranging from −0.19 to −0.05 ‰ for olivine, −0.25 to −0.10 ‰ for clinopyroxene, 0.57 to 0.60 ‰ for titanomagnetite and 0.86 to 2.34 ‰ for ilmenite, indicative of disequilibrium fractionation. A negative correlation between Fo content and δ26Mg value in olivine suggests that Mg isotopes fractionate as olivine undergoes fractional crystallization. Trapped liquid fractions, calculated based on Ce contents in apatite, suggest that rocks with high volatile-bearing mineral content have undergone re-equilibration with trapped liquids during cooling. The large disequilibrium Mg isotopic fractionation between silicates and Fe-Ti oxides is likely due to sub-solidus re-equilibration between minerals and trapped liquids. We propose that the extent of sub-solidus, diffusion-driven kinetic Mg isotopic fractionation in Fe-Ti oxide-bearing intrusions likely correlates with the volume of trapped liquids, which may serve as a significant medium accelerating ion exchange between silicates and Fe-Ti oxides. Moreover, mass balance calculations indicate that data of Mg isotopes on their own are insufficient to determine the petrogenesis of Fe-Ti oxides in layered intrusions. This insufficiency is primarily due to the low MgO content in titanomagnetite and ilmenite, where their separation causes minimal Mg isotopic fractionation of the melts.

Formation of PGE- and sulfide-bearing chromitites and associated anorthositic rocks in layered intrusions by the infiltration of reactive, Cl-rich fluid

The chromatographic model for chromitite formation previously presented is updated to include sulfide as a possible participating phase. In the model, chromite is precipitated at an upward-moving reaction front as a Cr-bearing (gabbro)norite protolith reacts with a Cl-rich fluid that becomes progressively undersaturated in pyroxene as it rises into hotter parts of the crystal pile, leaving an anorthositic residue. The liberation of Fe during the dissolution of orthopyroxene can drive concurrent sulfide saturation. If the reaction front encounters an orthopyroxenite the model produces a first-order approximation for the Merensky Reef section of anorthosite–chromite–orthopyroxenite. In addition, MELTS modelling shows that the isothermal addition of Cr 2 O 3 alone to a nearly solid (gabbro)norite assemblage increases the amount of both chromite and liquid at the expense of other silicate minerals owing to the liberation of Ca, Na and Si, the latter two acting as fluxing agents. A generalized constitutional zone refining model is presented in which a variety of spinel–silicate layering types (e.g. Bushveld magnetite layers and Skaergaard trough layering) can develop over time.

Apatite and pyroxene as records of magmatic–hydrothermal processes and platinum-group mineral (PGM) formation in the Wengeqi mafic–ultramafic intrusion, Inner Mongolia, China: The role of oxidized, H2O-rich magmas

The Devonian Wengeqi mafic–ultramafic intrusion, situated on the northern margin of the North China Craton (NCC) — an Andean-style convergent margin during the Paleozoic — hosts many platinum-group minerals (PGMs), especially within the S-deficient, magnetite-rich clinopyroxenite zones. These PGMs occur in two distinct associations: Pt-rich PGMs (e.g., sperrylite) closely associated with primary magnetite and Pd-rich PGMs (e.g., sudburyite, kotuskite, arsenopalladinite) associated with secondary minerals (e.g., actinolite, pyrite). The mechanisms underlying the formation of PGMs in S-deficient rocks and the spatial decoupling of various PGM types remain elusive. The relationship of PGM formation and characteristics of magmas at convergent margins is also not well understood. In this contribution, we utilized apatite and clinopyroxene textures and chemistry alongside whole-rock SrNd isotopes to characterize i) the nature of the parental magma from which the Wengeqi intrusion crystallized, and ii) the magmatic–hydrothermal processes that operated to generate the Pt- and Pd-rich PGM. Based on the composition of clinopyroxene and clinopyroxene–melt partition coefficients, the parental magma of the Wengeqi intrusion is estimated to have an arc-like affinity on a primitive mantle-normalized trace-element diagram. This, together with the EMI-like SrNd isotope signature, implies that the Wengeqi magma was sourced from metasomatized SCLM beneath the NCC with an EMI-like composition. Three types of apatite (Ap1, Ap2, and Ap3) were identified within the intrusion. Ap1 and Ap2 are magmatic in origin, and appear as isolated grains, whereas Ap3 occurs as stringers or heterogeneous domains within Ap1 and Ap2, and likely resulted from hydrothermal modification of magmatic apatite. Notably, the abundant Ap2 exhibits higher VS contents and Eu/Eu* ratios than the less common Ap1, and contains S predominantly in the form of S6+, suggesting that the Wengeqi magma was relatively oxidized, with fO2 > FMQ + 1.2. Based on the chemistry of magmatic apatite, the Wengeqi magma had ∼5 wt% H2O, which, together with its high fO2, facilitated crystallization of magnetite, causing reduction of the magma by removal of Fe3+. This reduction process promoted PGM nucleation by decreasing PGE solubility in the magma, leading to the association of PGM with magnetite. Additionally, the oxidized, H2O-rich magma likely released oxidizing fluids, selectively mobilizing Pd rather than Pt, separating Pt-rich PGMs from Pd-rich PGMs. The budget of PGE in the parental magma could have been increased by i) metasomatism of the SCLM source (e.g., by carbonatitic fluids), which would have elevated the concentration of PGE in the mantle source, and ii) the high fO2 and H2O levels of the magma, which would have delayed sulfide saturation. Accordingly, mantle metasomatism and high fO2–H2O are deemed favorable for enrichment of PGE in magmas within convergent margins.

SIMS U-Pb dating of baddeleyite-zircon pairs in mafic rocks to determine the ages of magmatic mineralization and hydrothermal remobilization in a Ni-Cu-(PGE) deposit

Ni-Cu-(PGE) sulfide deposits associated with mafic–ultramafic rocks are the most important sources of Ni and platinum-group elements (PGE) in the world. These deposits also contain significant amounts of Cu. Such deposits are generally considered to have formed by multiple stages of primary magmatic concentration and secondary hydrothermal remobilization. However, constraining the ages of Ni-Cu-(PGE) sulfide deposits has proven challenging, particularly those that have experienced post-magmatic hydrothermal overprinting and remobilization. The lack of robust geochronology data has hindered understanding of the geological controls on this important type of mineralization. The Chibaisong Ni-Cu-(PGE) sulfide deposit in the North China Craton is characterized by disseminated and net-textured ores formed by magmatic processes and overprinted by hydrothermal Cu-rich vein stockwork. The Cu-rich vein stockwork is fracture-controlled, and contains a mineral assemblage of Ni-Cu sulfides (chalcopyrite, pyrrhotite, pentlandite), amphibole and quartz. Chalcopyrite in the hydrothermal stockwork is relatively depleted in Ni but enriched in Ag and Cd compared with disseminated magmatic chalcopyrite, typical of hydrothermal superimposed ores as documented elsewhere. We identified baddeleyite-zircon pairs associated with Ni-Cu sulfides in hydrothermal superimposed ores of the Chibaisong deposit, in which the baddeleyite is unequivocally of primary igneous origin whereas the zircon represents the replacement product of baddeleyite during hydrothermal alteration. In situ SIMS U-Pb dating of baddeleyite and zircon yielded weighted mean 207Pb/206Pb ages of 2181 ± 21 Ma and 1892 ± 33 Ma, respectively, interpreted as the timing of magmatic mineralization and subsequent hydrothermal remobilization of the Ni-Cu-(PGE) deposit. Our results explain the large discrepancies in sulfide Re-Os ages previously obtained from this deposit. This study demonstrates that on the basis of detailed BSE imaging, in situ SIMS U-Pb dating of baddeleyite-zircon pairs can provide robust age constraints for both magmatic mineralization and hydrothermal remobilization of Ni-Cu-(PGE) sulfide deposits hosted in mafic–ultramafic intrusions, although further studies are needed to test whether the formation of such deposits commonly entails multiple stages of hydrothermal remobilization. Since baddeleyite or baddeleyite-zircon pairs are common accessory minerals in Ni-Cu-(PGE)-bearing mafic–ultramafic rocks, the dating approach employed in this study may be applicable to similar deposits elsewhere.

Monchegorsk Mafic–Ultramafic Layered PGE-Bearing Complex (2.5 Ga, Kola Region, Russia): On the Problem of Relationships between Magmatic Phases Based on the Study of Cr-Spinels

The composition of Cr-spinels from rocks of the Monchegorsk layered complex (2.5 Ga) basically corresponds to the evolutionary trend that is typical for layered mafic–ultramafic intrusions (late magmatic phases contain Cr-spinels enriched in Fe and depleted in Mg, Cr, and Al). Cr-spinels within the Dunite Body of the Sopcha massif are almost identical to those within the Dunite Block rocks and are close to those from harzburgite of the NKT massif. Cr-spinels within the satellite bodies of the Ore Layer 330 are shown to have zonal structure, which confirms their origin from a new portion of melt, which may have been injected with several pulses. The composition of accessory Cr-spinels may indicate that the layered complex of rocks of the South Sopcha massif was formed from the most evolved portion of magmatic melt (linked with the Monchetundra intrusion), and its vein complex may be considered the one formed at the final stages of the magmatic system evolution. The composition of Cr-spinels from the Pentlandite Gorge mafic–ultramafic rocks may indicate that they are fragments of the NKT massif and not of the Monchetundra massif, as it was believed earlier.

Discovery of mafic dikes in northeastern Tibet plateau belonging to the Emeishan large igneous province: Implications for paleocontinental reconstruction and mineral exploration

Due to the lack of paleomagnetic data and paleoclimatic records, the paleocontinental belonging of the Yidun terrane in northeastern Tibet plateau is debated. In this paper, we use the distribution of the Emeishan large igneous province (ELIP) to put the issue to rest. The ELIP is the product of mantle plume activity, which took place at 260 ± 3 Ma in the western margin of the Yangtze craton. The Yangtze craton is the northern part of the South China paleocontinental block. Our new discovery of four mafic dikes in the Yidun terrane with ages and chemistry like the ELIP strongly supports a new interpretation that this terrane was an integral part of the Yangtze craton during the ELIP magmatic event. Baddeleyites from these mafic dikes yield the U–Pb ages of 257.1 ± 4.8, 259.8 ± 8.5, 260.2 ± 4.5 and 261.5 ± 6.8 Ma for each of these dikes, which are similar to the zircon U-Pb ages of the mafic–ultramafic intrusions of the ELIP within the Yangtze craton. The Yidun mafic dikes and some high-Ti basalts of the ELIP within the Yangtze craton have similar Sr-Nd isotope compositions and mantle-normalized incompatible trace element distribution patterns, indicating similar mantle source compositions. Mixing calculation using Sr-Nd isotope compositions shows that the parental magmas for the Yidun mafic dikes experienced only 2–3 % crustal contamination. Partial melting modelling shows that the primary magmas for the Yidun mafic dikes were produced by 5–6 % mantle partial melting at the depths > 85 km below surface, consistent with mantle plume-related magmatism in a continental setting. The Yidun terrane is a new exploration frontier for magmatic Fe-Ti-V oxide deposits that are present elsewhere in the ELIP.

Occurrence and enrichment of cobalt and nickel in the Yindongshan ultramafic–mafic intrusion-hosted iron deposit, western Hubei Province, China

The Yindongshan iron deposit in western Hubei Province of China is hosted within Ordovician ultramafic–mafic intrusions. Recent field geological surveys have detected cobalt (Co) and nickel (Ni) enrichment within the Yindongshan clinopyroxenite, suggesting good potential for subeconomic Co-Ni mineralization. This study investigated the occurrence modes and enrichment processes of Co and Ni in the Yindongshan deposit through field geology and in situ analysis of the rock texture, geochronology, and geochemistry of sulfides, Fe-Ti oxides, and silicate minerals. The Yindongshan clinopyroxenites were emplaced at 440.2 ± 7.2 Ma via titanite LA-ICP-MS U-Pb dating, and underwent extensive post-magmatic metamorphism at 401.2 ± 8.6 Ma via apatite U-Pb dating. This metamorphism led to the widespread formation of amphibole via the replacement of clinopyroxene. Subsequently, hydrothermal epidote-albite veins, calcite-pyrite veins, and later actinolite veins developed. Pyrites from both clinopyroxenites and calcite veins show limited δ34S variations from −5.4 ‰ to −1.2 ‰, suggesting a magmatic sulfur source. Late-vein actinolites display geochemical characteristics distinct from those of amphiboles, indicating possible involvement of external fluids. LA–ICP–MS trace element results reveal a general increase in Co and Ni contents from silicate minerals and Fe-Ti oxides to pyrite and from earlier-crystallized coarse-grained clinopyroxenite to later medium- to fine-grained clinopyroxenite. The highest Co and Ni contents observed in pyrite from coarse-grained clinopyroxenite suggest their preferential incorporation into early sulfide minerals and then progressively depleted through magmatic evolution such as fractional crystallization. The positive correlation between Co and Ni with Fe in pyrite, along with the consistent parallel time-resolved LA–ICP–MS depth profiles among different mineral phases, indicates that isomorphic substitution occurred in pyrite. In silicate minerals, the Co and Ni contents increase from pyroxene, amphibole, to actinolite, with almost no Co or Ni present in epidote. The elevated Co and Ni contents in metamorphic amphiboles are attributed to their remobilization from magmatic pyrite to newly formed amphiboles. During the late hydrothermal phase, external fluids might transport additional Co and Ni, contributing to higher concentrations in late actinolite veins. In general, Co and Ni in the Yindongshan iron deposit are primarily hosted in sulfide minerals and can be remobilized during regional metamorphism and metasomatism. Thus, magmatic iron or iron–titanium oxide deposits hosted by mafic–ultramafic intrusions with sulfide mineralization may serve as promising targets for further Co-Ni exploration.

Finding and identifying platinum group elements in the Eastman layered mafic intrusion

Platinum group elements (PGEs) are commonly hosted by base metal sulfides (BMSs, e.g. chalcopyrite or pentlandite) or platinum group minerals (PGMs). PGE-bearing phases are generally small, ranging from tens of nanometres to a few micrometres. In addition, PGEs can be hosted in PGMs, either intimately associated with BMSs or spatially separated. This poses a difficulty in their detection and analysis, and leads to uncertainty in identification of their mineral hosts. Their erratic occurrence introduces a substantial nugget effect in bulk rock assays, used to evaluate deposit economics on a larger scale. Knowledge of PGE hosts has a direct influence on resource management and extraction efficiency, making the understanding of mineral distribution important for processing. The Eastman Ultramafic Intrusion is a layered mafic–ultramafic intrusive complex in the Eastern Kimberley of Western Australia. Samples from Cu–Co–Ni–PGE exploration drilling at Eastman were bulk-assayed and found to contain up to 2.39 ppm PGEs. The rocks have been strongly altered and no longer represent their primary magmatic mineral assemblage and textures. To better understand the Eastman PGE mineralogy, we applied a multi-method approach of quantitative analytical electron microscopy, 3D scanning and in situ mass spectrometry. We find that Pt is primarily hosted in sperrylite, whereas Pd is mainly associated with kotulskite, pseudomertieite, testibiopalladite, sudburyite and michenerite. Additionally, minor Pt and Pd occur in solid solution within cobaltite, as well as Rh-rich cobaltite (hollingworthite). Spatially, PGMs and cobaltite are mostly clustered on a millimetric scale, and BMSs on a micrometric scale.

An Architecture of Enhanced Profiling Assurance for IoT Networks

Attacks launched from IoT networks can cause significant damage to critical network systems and services. IoT networks may contain a large volume of devices. Protecting these devices from being abused to launch traffic amplification attacks is critical. The manufacturer usage description (MUD) architecture uses pre-defined stateless access control rules to allow or block specific network traffic without stateful communication inspection. This can lead to false negative filtering of malicious traffic, as the MUD architecture does not include the monitoring of communication states to determine which connections to allow through. This study presents a novel solution, the enhanced profiling assurance (EPA) architecture. It incorporates both stateless and stateful communication inspection, a unique approach that enhances the detection effectiveness of the MUD architecture. EPA contains layered intrusion detection and prevention systems to monitor stateful and stateless communication. It adopts three-way decision theory with three outcomes: allow, deny, and uncertain. Packets that are marked as uncertain must be continuously monitored to determine access permission. Our analysis, conducted with two network scenarios, demonstrates the superiority of the EPA over the MUD architecture in detecting malicious activities.

Formation of orthopyroxene-magnetite symplectites by reactive melt flow: Insights into the Shangzhuang layered intrusion in Beijing, China

Interstitial microstructures in layered intrusions can provide crucial insights into the formation, transport, evolution, and solidification processes of magma. The symplectites commonly observed in the Shangzhuang layered intrusions in Beijing, China, can be classified into three types based on their occurrence and related primocryst minerals. Regardless of variation in types, the vermicular symplectites consistently exhibit a volume ratio of magnetite to orthopyroxene at approximately 1:4. Orthopyroxene in the symplectites shows no geochemical difference from those primocrysts. Inter-cumulus hornblende formed during the late stage after the formation of symplectites so that the symplectites are always enclosed by hornblende. By utilizing the hornblende geothermobarometer, we have also constrained that the symplectites have been formed within a relatively wide temperature range of 1040–915 °C through a reaction between the interstitial immiscible Fe-rich melt and the primocryst olivine and orthopyroxene. The reaction can be simplified as Ol/Opx (primocryst) + Fe-rich melt → Opx (symplectite) + Mt (symplectite). Besides, based on the mass balance and reaction results, the Si/O ratio of Fe-rich melt is estimated to be 1:3. The study of these symplectites contributes to refining the processes of reactive melt flow in mafic layered intrusions during late-stage magmatic crystallization.

Experimental Constraints on the Storage Conditions and Differentiation of High-Ti Basalts from the Panzhihua and Hongge Layered Intrusions, SW China

Abstract High-Ti basalts are commonly believed to represent parental magmas leading to the formation of mafic-ultramafic layered intrusions, such as Late Permian Panzhihua and Hongge in the Emeishan Large Igneous Province (SW China). Consequently, elucidation of the crystallisation and crustal differentiation of high-Ti basalts is critical for our understanding of the petrogenesis of these layered intrusions and the associated oxide ore mineralisation. Here, we present the results of crystallisation experiments carried out in internally heated pressure vessels using a primitive high-Ti basaltic composition. The experiments were conducted at 100 and 300 MPa, in the temperature interval of 950–1200 °C and with water activities (aH2O) from 0 to 1. The oxygen fugacity (fO2) was controlled and varied from FMQ −1 to FMQ +3.3 log units (FMQ corresponds to fayalite-quartz-magnetite buffer). The main mineral phases are olivine, clinopyroxene and plagioclase, accompanied by Cr-Fe-Ti-oxides, orthopyroxene, apatite and amphibole, depending on the conditions. Redox conditions primarily influence the stability fields of Cr-Fe-Ti oxides. Clinopyroxene, orthopyroxene and amphibole are pressure-dependent and have larger stability fields under high pressure conditions. The olivine→orthopyroxene and olivine→amphibole peritectic reactions are observed. Comparisons of phase equilibria between this study and experiments conducted with parental magma of Skaergaard layered intrusion demonstrate the effect of bulk system composition. For instance, ilmenite crystallisation is determined not only by intrinsic parameters such as fO2 but also by additional compositional parameters (e.g. melt Ti, Fe, Al and Mg content). Although COMAGMAT and MELTS modelling results generally reproduce the crystallisation sequence, only the stability field of clinopyroxene and its composition are perfectly modelled. The comparison of experimental results with the rocks from the lowest units of Panzhihua and Hongge layered intrusions are applied to constrain storage conditions in the magma reservoirs. Compared to Hongge, we conclude that the Panzhihua magma chamber was probably located at a shallower depth (~3–6 km), that magma crystallisation started at lower temperatures (~1125–1100 °C), higher fO2 (~FMQ + 1 to FMQ + 2) and that its initial melt H2O content was lower (~0.5–1 wt. %).

Petrogenesis of the Dalaku’an Mafic–Ultramafic Intrusion in the East Kunlun, Xinjiang: Constraints from the Mineralogy of Amphiboles

The Dalaku’an mafic–ultramafic intrusion, located in the western segment of the East Kunlun, presents conducive conditions for the magmatic Cu-Ni sulfide deposits. According to the detailed petrographic observation, the amphiboles within distinct rock types were analyzed by EPMA analysis. The crystallization conditions, such as temperature, pressure, oxygen fugacity, and water content of the magma, were calculated to explore the genesis of the intrusion. The amphiboles were divided into three types: Amp-I, characterized by low silicon content but enrichment of aluminum, titanium, and alkali, predominantly comprising Tschermakitic hornblende and Magnesio-hornblende with mantle-derived traits; Amp-II, exhibiting elevated silicon content but diminished levels of aluminum, titanium, and alkali, primarily constituted of Magnesio-hornblende; whereas Amp-III manifests as Actinolitic hornblende, indicative of crustal origins. The calculated temperatures of amphiboles ranged between Amp-I (955–880) °C, Amp-II (852–774) °C, and Amp-III (761–760) °C; the pressures ranged between Amp-I (454–274) MPa, Amp-II (194–93) MPa, and Amp-III (101–84) MPa; the oxygen fugacities (△NNO) ranged between Amp-I (0.93–2.17), Amp-II (1.55–2.52), and Amp-III (1.89); and the water contents (H2Omelt) ranged from (6.69–8.67) to (5.90–7.32). The magma experienced multiple stages of crystallization and underwent complex magma evolution at different depths. The high oxygen fugacity and water content could be attributed to the subduction of the oceanic crust. The magma source of the Dalaku’an intrusion was metasomatized by fluids from subducting plates, thereby originating within a post-collision extension.