Element Patterns Research Articles

Mid-Jurassic volcanism at Bokhara River and insights into metasomatism in the lithospheric mantle of the Thomson Orogen, eastern Australia

Eastern Australia is covered by extensive, thick regolith, which obfuscates much of its basement geology, making geological sampling difficult. The Bokhara River diatremes erupted through the Thomson Orogen in eastern Australia and are covered by ∼300 m of Cretaceous regolith cover. Hitherto, these diatremes have only been characterised by magnetic anomaly surveys and private exploration drilling. The melts were assumed to be leucititic, owing to their proximity to Miocene leucitite centres to the south, while their position along the Cosgrove hotspot track led to the assumption that the diatremes erupted at ca 20 Ma. However, whole-rock chemistry shows that the diatremes are basanites and, according to 40Ar/39Ar dating, erupted during the mid-Jurassic (ca 180 Ma; estimated by reproducible slightly discordant ages), substantially older than the assumed age and coincident with widespread Mesozoic flood basalts across Gondwana. The basanites entrained abundant mantle material during accent, which contaminated the basanite with ∼12.8 wt% xenocrystic material. The xenoliths are all fertile spinel lherzolites with Mg# 87–89, CaO 2.64–5.90 wt% and Al2O3 2.87–3.83 wt% that have been cryptically metasomatised by a mafic silicate melt, which resulted in chromatographic rare-earth element patterns. This demonstrates that mantle metasomatism occurred during the Mesozoic in this part of eastern Australia, revealing another expression of intraplate volcanism prior to Australia rifting away from Gondwana. The identification and characterisation of this Jurassic volcanism hosting evidence for mantle metasomatism suggest that intraplate volcanism and mantle metasomatism are synonymous within orogenic eastern Australia, and not restricted to the Cenozoic.

Mechanistic mapping of random fields for stochastic finite element simulations of quasibrittle fracture

Spurious mesh sensitivity is a major challenge in continuum finite element (FE) simulations of damage and fracture of quasibrittle structures. It has been shown that the existing localization limiters, which largely focus on energy regularization, are insufficient for addressing the issue of mesh sensitivity in stochastic analysis. In this study, we investigate the mathematical algorithm for mapping the continuous random fields of material properties onto the FE meshes. This is a fundamental problem in stochastic FE analysis, which has profound implications for the mesh sensitivity in the prediction of the statistics of failure behavior. We adopt a continuum damage constitutive model, and develop a mechanistic mapping method. The projection of the random fields of material properties onto the FE mesh is governed by the prevailing damage pattern of the element. The damage pattern of each finite element is determined based on the spatial distribution of the damage of its surrounding elements. Meanwhile, the prevailing damage pattern also dictates the energy regularization of the constitutive response of the finite element. The combination of energy regularization and mechanistic mapping method ensures that, for each time increment, the random tangential stiffness tensor of each finite element is calculated in accordance with the ongoing damage pattern. A direct consequence of the model is that, depending on the damage pattern, the statistics of the tangential stiffness tensor could vary with the mesh size. The model is applied to stochastic FE analysis of both notched and unnotched flexural specimens under different loading configurations, which exhibit different failure behaviors. The numerical analysis also considers different correlation lengths of the random fields of material properties. The simulation shows that, with the energy regularization scheme, the commonly used local mapping and local averaging methods could yield considerable mesh dependence of the statistics of the peak load capacity. The result also reveals the effect of correlation length on the spurious mesh dependence. By relating the mapping algorithm to the underlying damage pattern, the present model is able to mitigate the mesh sensitivity for different specimen geometries, loading configurations, and correlation lengths.

The medieval croft plužina field system in a mountain region of central Europe: The interdisciplinary record of the earthen field boundaries in Debrné, Czechia

AbstractThe integration of archaeological, historical and geoarchaeological records represents a significant contribution to research into the medieval landscape. This study focuses on the medieval field system in the deserted village of Debrné, located in northeastern Bohemia, Czechia. The village features a well‐preserved croft plužina field system, a typical historical landscape of central Europe. The main and most visible elements of the field system are the earthen field boundaries, which were the focus of the geoarchaeological investigations. Archaeological excavations in trench S1 revealed a collection of larger stones at a depth of 1 m, potentially serving a drainage function akin to the observed plužina. Additionally, a boulder paving, identified as a remnant of a path between fields, provided insights into the historical use of the area. In trench S2, positioned closer to the village's core, layers with increasing stone content were recorded at a depth of 130 cm. However, the drainage structure observed in trench S1 was not replicated. The dating of earthen field boundaries indicated the creation of the terrace in the second half of the 16th century in trench S1. In trench S2, radiocarbon dating at a depth of 70 to 80 cm ranged from 1025 to 1175 A.D., predating the first written source about Debrné. Optically stimulated luminescence (OSL) dating in trench S2 suggested exposure to sunlight during the third century A.D. Archaeobotanical analysis of charred macroremains from trench S1 revealed 236 plant macroremains belonging to approximately 20 taxa, showcasing wild‐growing, collected useful species such as raspberry, blackberry and elderberry. Trench S2 yielded 23 plant macroremains belonging to 11 taxa, with similar species as trench S1. Pedological and micromorphological examinations displayed distinct layering in both trenches, showing up to six layers. Micromorphological analysis unveiled vuggy microstructures, varying grain sizes and elemental patterns, shedding light on different periods of occupation. Multidisciplinary investigations of the buried soils forming the earthen field boundaries discovered that the original soil cover comprised automorphic lixisols and cambisols, which also form under present conditions. These results underscore the importance of integrating pedological, geoarchaeological, archaeobotanical and physical data to comprehend the intricate nature of anthropogenic landscape changes.

Generative Adversarial Networks for Inverse Design of Two-Dimensional Spinodoid Metamaterials

The geometrical arrangement of metamaterials controls their mechanical properties, such as Young’s modulus and the shear modulus. However, optimizing the geometrical arrangement for user-defined performance criteria leads to an inverse problem that is intractable when considering numerous combinations of properties and underlying geometries. Machine-learning techniques have been proven to be effective and practical to accomplish such nonintuitive design tasks. This paper proposes an inverse design framework using conditional generative adversarial networks (CGANs) to explore and optimize two-dimensional metamaterial designs consisting of spinodal topologies, called spinodoids. CGANs are capable of solving the many-to-many inverse problem, which requires generating a group of geometric patterns of representative volume elements with target combinations of mechanical properties. The performance of the networks was validated by numerical simulations with the finite element method. The proposed inverse design framework vastly improves the efficiency of design exploration and optimization of spinodoid metamaterials.

Outlier Detection-aided Supervised Learning for Modeling of Thinned Cylindrical Conformal Array

In this paper, a scheme of outlier detection-aided supervised learning (ODASL) is proposed for analyzing the radiation pattern of a thinned cylindrical conformal array (TCCA), considering the impact of mutual coupling. The ODASL model has the advantage in speed improvement and memory consumption reduction, which enables a quick generation of the synthesis results with good generalization. The utilization of the active element pattern (AEP) technique in the model also contributes to the prediction of the array performance involving mutual coupling. The effectiveness of the ODASL model is demonstrated through a numerical example of the 12-element TCCA.

Trace element translocation patterns in the epigeous parts of 15 common Canadian urban plant species grown in a contaminated soil

Green initiatives and phytotechnologies, such as phytoremediation, hold great potential for the sustainable management of contaminated brownfields. One impediment to these initiatives is the lack of alternatives for the produced biomass due to the potential contamination of plants by trace elements. We conducted an experiment to quantify the accumulation and the translocation patterns of trace elements in the aboveground parts of fifteen desirable plants species used for these kinds of initiatives, i.e. urban predominance, ecological relevance, edibility, commercial prospective, and phytoremediation potential. The experiment was set-up in a tunnel-type greenhouse in which plants were grown in pots filled with contaminated urban soil containing Cu, Zn, Se, Ag and spiked with Cd. Our results indicated that different species exhibited differential abilities to accumulate and translocate trace elements in their aboveground biomass and furthermore, exhibited different bioconcentration factors. A clear exclusion of Cd allocation was observed in fruits and flowers. However, Cd content in edible parts was still above the standard recommendations for human consumption. Our results suggest potential candidates for phytoremediation by revealing different accumulation patterns, also highlighting the importance of characterizing trace elements in the soil for selecting the appropriate plant species based on project’s needs.

Genetic basis of variation in thermal developmental plasticity for Drosophila melanogaster body pigmentation.

Seasonal differences in insect pigmentation are attributed to the influence of ambient temperature on pigmentation development. This thermal plasticity is adaptive and heritable, and thereby capable of evolving. However, the specific genes contributing to the variation in plasticity that can drive its evolution remain largely unknown. To address this, we analysed pigmentation and pigmentation plasticity in Drosophila melanogaster. We measured two components of pigmentation in the thorax and abdomen: overall darkness and the proportion of length covered by darker pattern elements (a trident in the thorax and bands in the abdomen) in females from two developmental temperatures (17 or 28°C) and 191 genotypes. Using a GWAS approach to identify the genetic basis of variation in pigmentation and its response to temperature, we identified numerous dispersed QTLs, including some mapping to melanogenesis genes (yellow, ebony, and tan). Remarkably, we observed limited overlap between QTLs for variation within specific temperatures and those influencing thermal plasticity, as well as minimal overlap between plasticity QTLs across pigmentation components and across body parts. For most traits, consistent with selection favouring the retention of plasticity, we found that lower plasticity alleles were often at lower frequencies. The functional analysis of selected candidate QTLs and pigmentation genes largely confirmed their contributions to variation in pigmentation and/or pigmentation plasticity. Overall, our study reveals the existence and underlying basis of extensive and trait-specific genetic variation for pigmentation and pigmentation plasticity, offering a rich reservoir of raw material for natural selection to shape the evolution of these traits independently.

Exploration of Unggan weaving in Minang culture: An ethnomathematics study

Unggan weaving, an original cultural product of the Sijunjung people, especially in Unggan Village, is widely used as employee, traditional, and school uniforms once a week. However, the use of Unggan weaving in mathematics learning has yet to be widely explored. This research aims to reveal the mathematical elements of Unggan weaving as a learning vehicle more appropriate to students' culture. This research is qualitative research with an ethnographic approach. Data collection methods use in-depth interviews, documentation, and ethnographic notes. The interview subjects were Ernita, owner of Unggan Weaving (R-1), and Masniati, an employee of Unggan Weaving (R-2). Data analysis uses the results of interpretation and translation of the phenomena found, as well as based on the results of the informant's conception of the meaning and the informant's original language regarding the focus, which is combined verbally with the researcher's language after in-depth understanding through focus group discussions (FGD). The research results show that Unggan woven fabric contains mathematical elements of geometric transformation (translation, reflection, dilation, symmetry) and arithmetic number patterns. The results of this research can be recommended as material for developing school mathematics teaching materials based on local wisdom.

Plume-lithosphere interaction in the Comei Large Igneous Province: Evidence from two types of mafic dykes in Gyangze, south Tibet, China

Two suites of mafic dykes, T1193-A and T1194-A, outcrop in Gyangze area, southeast Tibet. They are in the area of Comei LIP and have indistinguishable field occurrences with two other dykes in Gyangze, T0902 dyke with 137.7±1.3 Ma zircon age and T0907 dyke with 142±1.4 Ma zircon age reported by Wang YY et al. (2016), indicating coeval formation time. Taking all the four diabase dykes into consideration, two different types, OIB-type and weak enriched-type, can be summarized. The “OIB-type” samples, including T1193-A and T0907 dykes, show OIB-like geochemical features and have initial Sr-Nd isotopic values similar with most mafic products in Comei Large Igneous Provinces (LIP), suggesting that they represent melts directly generated from the Kerguelen mantle plume. The “weak enriched-type ” samples, including T1194-A and T0902 dykes, have REEs and trace element patterns showing within-plate affinity but have obvious Nb-Ta-Ti negative anomalies. They show uniform lower εNd(t) values (–6––2) and higher 87Sr/86Sr(t) values (0.706–0.709) independent of their MgO variation, indicating one enriched mantle source. Considering their closely spatial and temporal relationship with the widespread Comei LIP magmatic products in Tethyan Himalaya, these “weak enriched-type” samples are consistent with mixing of melts from mantle plume and the above ancient Tethyan Himalaya subcontinental lithospheric mantle (SCLM) in different proportions. These weak enriched mafic rocks in Comei LIP form one special rock group and most likely suggest large scale hot mantle plume-continental lithosphere interaction. This process may lead to strong modification of the Tethyan Himalaya lithosphere in the Early Cretaceous.©2024 China Geology Editorial Office.

Concentration‐number (C‐N) fractal models reveal the distribution pattern of the elements in ancient nephrite measured by portable X‐ray fluorescence: Based on nephrite objects excavated from different sites in Nanyang, Henan Province

AbstractChanges in the composition of various chemical elements in ancient nephrite artifacts due to prolonged burial are critical factors that should not be underestimated. However, the increasingly stringent heritage management has made many techniques impractical. Consequently, portable X‐ray fluorescence (pXRF) has become an indispensable nondestructive field analysis method. This paper aims to make use of the pXRF dataset to distinguish which elements tested are endogenous or exogenous, as well as to gauge which elements have been affected by stronger burial effects. More specifically, we carry out this work on the example of 103 pieces of nephrite excavated from different cemeteries in the Nanyang area. In addition to traditional statistical techniques, a new tool, the concentration‐number (C‐N) fractal method can shed new light on the analysis of the distribution patterns of different elements in excavated nephrite. The anomalous boundaries generated by the method have clear geochemical significance and can be delineated between background zone and disturbed regions. The degree of resistance of different elements to fluctuations in external factors was assessed, which has a direct relationship with the content of the buried soil. Considering the richness of the model, it has the potential to be used in archaeometrics.

Genesis of the Nuri Cu‐W‐Mo Deposit, Tibet, China: Constraints from in situ Trace Elements and Sr Isotopic Analysis of Scheelite

AbstractThe Nuri deposit is the only Cu‐W‐Mo polymetallic deposit with large‐scale WO3 resources in the eastern section of the Gangdese metallogenic belt, Tibet, China. However, the genetic type of this deposit has been controversial since its discovery. Based on a study of the geological characteristics of the deposit, this study presents mineralization stages, focusing on the oxide stage and the quartz‐sulfide stage where scheelite is mainly formed, referred to as Sch‐A and Sch‐B, respectively. Through LA‐ICP‐MS trace element and Sr isotope analyses, the origin, evolutionary process of the ore‐forming fluid and genesis of the ore deposit are investigated. Scanning Electron Microscope‐Cathodoluminescence (SEM‐CL) observations reveal that Sch‐A consists of three generations, with dark gray homogenous Sch‐A1 being replaced by relatively lighter and homogeneous Sch‐A2 and Sch‐A3, with Sch‐A2 displaying a gray CL image color with vague and uneven growth bands and Sch‐A3 has a light gray CL image color with hardly any growth band. In contrast, Sch‐B exhibits a ‘core‐rim’ structure, with the core part (Sch‐B1) being dark gray and displaying a uniform growth band, while the rim part (Sch‐B2) is light gray and homogeneous. The normalized distribution pattern of rare earth elements in scheelite and Sr isotope data suggest that the early ore‐forming fluid in the Nuri deposit originated from granodiorite porphyry and, later on, some country rock material was mixed in, due to strong water‐rock interaction. Combining the O‐H isotope data further indicates that the ore‐forming fluid in the Nuri deposit originated from magmatic‐hydrothermal sources, with contributions from metamorphic water caused by water‐rock interaction during the mineralization process, as well as later meteoric water. The intense water‐rock interaction likely played a crucial role in the precipitation of scheelite, leading to varying Eu anomalies in different generations of scheelite from the oxide stage to the quartz‐sulfide stage, while also causing a gradual decrease in oxygen fugacity (fO2) and a slow rise in pH value. Additionally, the high Mo and low Sr contents in the scheelite are consistent with typical characteristics of magmatic‐hydrothermal scheelite. Therefore, considering the geological features of the deposit, the geochemical characteristics of scheelite and the O‐H isotope data published previously, it can be concluded that the genesis of the Nuri deposit belongs to porphyry‐skarn deposit.

Electronic Focus Steering Capabilities of a Diagnostic-Type Linear Ultrasound Array Designed for High Power Therapy and Its Visualization

The focus steering capabilities of a 1 MHz linear phased array transducer (64 rectangular elements, 14.8 × 51.2 mm aperture) intended for drug delivery applications in abdominal organs were assessed and compared with its design-stage computer model. Acoustic fields generated by the transducer and predicted by the models of an ideal array with uniformly vibrating elements and either a plane or a cylindrically focused surface were simulated using the Rayleigh integral and angular spectrum methods. The boundary conditions for the transducer were reconstructed from acoustic holography measurements performed for selected focusing configurations of the array and also synthesized from holography data measured for each of its individual elements. It was shown that the transducer field with electronic focus steering can be accurately synthesized based on the holography data of its elements, which significantly simplified acoustic field characterization. Variability of the power and directivity patterns of the array elements were analyzed. A twofold smaller range of electronic steering in the transverse direction for the transducer compared to its computer model is discussed.

Spectroscopic r-process Abundance Retrieval for Kilonovae. II. Lanthanides in the Inferred Abundance Patterns of Multicomponent Ejecta from the GW170817 Kilonova

In kilonovae, freshly synthesized r-process elements imprint features on optical spectra, as observed in AT2017gfo, the counterpart to the GW170817 binary neutron star merger. However, measuring the r-process compositions of the merger ejecta is computationally challenging. Vieira et al. introduced Spectroscopic r-process Abundance Retrieval for Kilonovae (SPARK), a software tool to infer elemental abundance patterns of the ejecta and associate spectral features with particular species. Previously, we applied SPARK to the 1.4-day spectrum of AT2017gfo and inferred its abundance pattern for the first time, characterized by electron fraction Y e = 0.31, a substantial abundance of strontium, and a dearth of lanthanides and heavier elements. This ejecta is consistent with wind from a remnant hypermassive neutron star and/or accretion disk. We now extend our inference to spectra at 2.4 and 3.4 days and test the need for multicomponent ejecta, where we stratify the ejecta in composition. The ejecta at 1.4 and 2.4 days is described by the same single blue component. At 3.4 days, a new redder component with lower Y e = 0.16 and a significant abundance of lanthanides emerges. This new redder component is consistent with dynamical ejecta and/or neutron-rich ejecta from a magnetized accretion disk. As expected from photometric modeling, this component emerges as the ejecta expands, the photosphere recedes, and the earlier bluer component dims. At 3.4 days, we find an ensemble of lanthanides, with the presence of cerium most concrete. This presence of lanthanides has important implications for the contribution of kilonovae to the r-process abundances observed in the Universe.

Extracting Meaningful Environmental and Age Information From a c. 2.4–2.2 Ga Peritidal Phosphorite: The Turee Creek Group, Western Australia

AbstractPhosphorites can record oceanic conditions during their deposition, but the faithful retention of primary information in Paleoproterozoic deposits can be mitigated by post‐depositional processes. Here, we examine a peritidal phosphorite within a microbialite reef complex in the 2.4–2.2 Ga Turee Creek Group in Western Australia to assess the environmental information retained. Field mapping and petrography distinguishes between authigenic and locally transported phosphorite fragments, each of which contains unique information regarding the deposit. Elemental mapping and laser‐ablation analyses differentiate the impact of depositional versus early diagenetic versus metamorphic processes within these fragments. Samples within a near‐shore pebble conglomerate have mixed riverine‐oceanic signals and lack cerium anomalies, consistent with the depositional environment. Clasts from off‐shore peloidal grainstone beds retain “hat‐shaped” patterns with small negative cerium anomalies, reflective of transport and redeposition within potentially oxic seawater. U‐Pb isotopic dates range from ∼1.8 to 2.3 Ga and are generally uncorrelated with rare earth element and yttrium data. The youngest date (∼1.8 Ga) is associated with recrystallized apatite, with concave down, middle rare earth element enriched patterns. A potential depositional age, ∼2.3 Ga, is associated with massive apatite in a chert‐rich clast that has rare earth element patterns reflective of riverine‐oceanic signals. Overall, the peritidal system in the reef was dynamic, with potentially oxic seawater that had a strong riverine influence. Local recycling and reworking, early diagenesis, and later orogenic events impacted the preserved geochemical signals and together show that spatially resolved geochronological and geochemical data are ideal for interpreting ancient phosphorites.

Phylogenomic curation of Ovate Family Proteins (OFPs) in the U's Triangle of Brassica L. indicates stress-induced growth modulation.

The Ovate Family Proteins (OFPs) gene family houses a class of proteins that are involved in regulating plant growth and development. To date, there is no report of the simultaneous functional characterization of this gene family in all members of U's Triangle of Brassica. Here, we retrieved a combined total of 256 OFP protein sequences and analyzed their chromosomal localization, gene structure, conserved protein motif domains, and the pattern of cis-acting regulatory elements. The abundance of light-responsive elements like G-box, MRE, and GT1 motif suggests that OFPs are sensitive to the stimuli of light. The protein-protein interaction network analysis revealed that OFP05 and its orthologous genes were involved in regulating the process of transcriptional repression through their interaction with homeodomain transcription factors like KNAT and BLH. The presence of domains like DNA binding 2 and its superfamily speculated the involvement of OFPs in regulating gene expression. The biotic and abiotic stress, and the tissue-specific expression analysis of the RNA-seq datasets revealed that some of the genes such as BjuOFP30, and BnaOFP27, BolOFP11, and BolOFP10 were highly upregulated in seed coat at the mature stage and roots under various chemical stress conditions respectively which suggests their crucial role in plant growth and development processes. Experimental validation of prominent BnaOFPs such as BnaOFP27 confirmed their involvement in regulating gene expression under salinity, heavy metal, drought, heat, and cold stress. The GO and KEGG pathway enrichment analysis also sheds light on the involvement of OFPs in regulating plant growth and development. These findings have the potential to serve as a forerunner for future studies in terms of functionally diverse analysis of the OFP gene family in Brassica and other plant species.

Downstream network transformations dissociate neural activity from causal functional contributions

Neuroscientists rely on distributed spatio-temporal patterns of neural activity to understand how neural units contribute to cognitive functions and behavior. However, the extent to which neural activity reliably indicates a unit's causal contribution to the behavior is not well understood. To address this issue, we provide a systematic multi-site perturbation framework that captures time-varying causal contributions of elements to a collectively produced outcome. Applying our framework to intuitive toy examples and artificial neural networks revealed that recorded activity patterns of neural elements may not be generally informative of their causal contribution due to activity transformations within a network. Overall, our findings emphasize the limitations of inferring causal mechanisms from neural activities and offer a rigorous lesioning framework for elucidating causal neural contributions.

The influence of the environmental factors on the accumulation patterns of toxic elements in Plantago lanceolata sampled in the area under strong anthropopressure

The study aims to explore the environmental factors which activate accumulation abilities of Plantago lanceolata in the research area under strong anthropopressure resulting from the long-term pollution originating from copper mining-metallurgical activities in Southeastern Europe. Sampling was performed at the most endangered sites regarding its proximity to the major and/or secondary pollution sources, as well at the control site. The content of toxic elements (Al, Cu, Fe, Mn, Ni, Pb and Zn) was determined in the roots, leaves, stalks and flowers of P. lanceolata. The anthropogenic origin of environmental contamination was denoted through the high concentrations of Cu, Pb and Zn in the leaves of P. lanceolata, reaching toxic levels, combined with the enrichment of plant parts (Enrichment factor >2), especially with Cu (as well as with Al, Fe, Ni and Zn) in samples from the immediate proximity to the copper smelter or at the prevailing wind directions. Biomonitoring potential, assessed through the correlations between toxic element content, as well as the values of Enrichment factor, was indicated for roots (in the case of Cu), all the aboveground plant parts (Fe) and stalks (Zn). The results have shown that the contents of toxic elements in plant parts as well as phytoremediation of P. lanceolata were dependent on soil element content, soil physico-chemical properties and soil enzyme activities, which were regarded as the main environmental drivers affecting phytoremediation ability. The analysis of biological factors (bioconcentration, translocation and bioaccumulation factor) indicated exclusion strategy and possible usage of P. lanceolata in phytostabilization of Zn. The results indicated that the study area is 'environmental hotspot' with potential threat to human health due to the high levels of bioaccumulation of the investigated toxic elements in P. lanceolata parts.

Geochemical Characteristics of Seabed Sediments in the Xunmei Hydrothermal Field (26°S), Mid-Atlantic Ridge: Implications for Hydrothermal Activity

The compositions of metalliferous sediments associated with hydrothermal vents can provide key geochemical data for locating seafloor sulfides. In this study, we present the geochemistry of seabed sediments from the Xunmei hydrothermal field (HF) in the South Mid-Atlantic Ridge (SMAR). The results indicate that the sediments are mainly composed of pelagic material (biogenic calcium components), basaltic debris, iron-manganese oxides, and hydrothermal components. The sediments are significantly enriched in Cu, Zn, Fe, and Co deriving from hydrothermal fluids, as well as Mn, V, Mo, U, and P, which are primarily scavenged from seawater. The northeastern Xunmei has the highest concentrations of Cu and Zn, while the northeastern, northern, and southern regions are characterized by great inputs of Fe. Manganese and Mo are mainly enriched in the western and southern parts and show a strong positive correlation, indicating that Mo is mainly scavenged by Mn oxides. Uranium, P, and Fe exhibit strong positive correlations, suggesting that they coprecipitate with Fe from hydrothermal plumes. Vanadium and Co are introduced into sediments in different ways: V is scavenged and coprecipitated by hydrothermal plumes, and Co is derived from sulfide debris. Based on the contents of Cu and Zn and Cu/Fe (0.159), Zn/Fe (0.158), and Fe/Mn (1440) ratios, it can be inferred that a high-temperature hydrothermal vent existed in northeastern Xunmei. In combination with the distribution patterns of the above elements, the hydrothermal vents in the southern part ceased erupting after a short period of activity. In addition, the high Mn anomaly and the high U/Fe ratios at the boundaries of the investigated area indicate the presence of a relatively oxidized environment in southwestern Xunmei.

Two episodes of mid-Neoproterozoic mafic magmatism in the Hong'an Terrane, Central China: Records of continental rifting during the breakup of the Rodinia supercontinent

The mid-Neoproterozoic (800–635 Ma) tectonic regime along the northern margin of the Yangtze Block is still debated, particularly the timing and mode of transition from a subduction-related setting to a rifting-related setting. The new identification of two episodes of mafic magmatism, represented by (I) 736–710 Ma Daleishan and (II) 635 Ma Hong'an intrusions in the Hong'an Terrane, central China, provides new constraints on the nature of their mantle source and tectonic evolution of the northern Yangtze Block. (I) Daleishan mafic rocks are tholeiitic in composition and exhibit N-MORB- to arc-like trace element patterns. They have variable whole-rock initial 87Sr/86Sr (0.7041 to 0.7092), εNd(t) (−2.98 to +2.17), and εHf(t) (+3.37 to +10.25) values. Their magmatic zircons preserve relatively homogeneous δ18O (+4.50 to +6.01 ‰) and highly variable εHf(t) (+1.3 to +13.1) values. Chemical compositions and modeling results suggest that Daleishan rocks were derived from a depleted asthenospheric mantle source with involvement of recycled sediment component, and the magma subsequently underwent 5–15% contamination by the wall-rocks during its emplacement. (II) Hong'an mafic rocks mainly show E-MORB- to arc-like geochemical features with more enriched HfNd isotopes [zircon εHf(t) = −3.0 to +3.6; whole-rock εNd(t) = −6.87 to −0.75, and εHf(t) = −0.50 to +2.00], suggesting they were derived from the interactions between the asthenosphere and the previously-metasomatized lithospheric mantle. Integrating the new data with previous results for the Neoproterozoic rocks in the northern margin of the Yangtze Block (including the Qinling-Dabie orogen), we emphasize that episodic extension-related asthenosphere upwelling in a continental rifting setting, coupled with interactions between the asthenosphere and the lithosphere, played a prominent role in the formation of the 780–635 Ma bimodal-type magmatic rocks and diverse geochemical features in the mafic counterparts.

Petrography, geochemistry and detrital zircon U–Pb dating of the Pliocene‐Pleistocene Dupi Tila Formation from the Lalmai Anticline, Bengal Basin: Regional tectonic implications

The Bengal Basin is a well‐known foreland basin that archives the tectonic evolution of the Himalayan and Indo‐Burman Ranges (IBR). The Dupi Tila Formation is the youngest among the stratigraphic successions of the Bengal Basin, which witnessed the last phase of the Himalayan uplift. However, there is still controversy regarding sediment provenances since the Himalayan and IBR are in the late Neogene exhumation stage. In this study, the petrographical and geochemical compositions of the Dupi Tila sandstones from the Lalmai Anticline of the Bengal Basin are examined to infer the source rocks, tectonic settings, palaeoclimate and weathering intensity in provenance areas. The detrital modes and geochemical discriminations, as well as Chondrite‐normalized rare earth elements patterns with enrichment in light rare earth elements and nearly flat heavy rare earth elements and negative Eu anomalies (average Eu/Eu* = 0.77) indicate dominantly felsic source rocks. The geochemical data also suggest that these source rocks in provenance areas were influenced by weak to moderate chemical weathering (chemical index of alteration: 65.64–75.62) and multiple recycling under warm and humid to semi‐humid climatic conditions. The detrital zircon ages show three dominant peaks at ca. 100, 500 and 1000 Ma with minor 1700 Ma. The amount of young zircon grains (<120 Ma) is noticeably higher (~18%) in this Lalmai outcrop compared to the Dupi Tila samples from the Sylhet Trough and Chittagong‐Tripura Fold Belt. Results from integrated zircon geochronology and geochemistry indicate that the detritus are likely derived from a recycled orogen provenance related mainly to active continental margin setting with subordinate influence from passive setting. Therefore, the regionally extensive Himalayan Orogen appears to be the primary sediment source, with additional mixing from the IBR and recycled sediments originating from the Gangdese batholith of the Trans‐Himalaya.