Enriched Component Research Articles

Ridgeward flow of compositionally heterogeneous mantle produces near-ridge seamount chains in the South Pacific

Many near-ridge seamounts and seamount chains in the Pacific Ocean have a nonplume origin. Yet, their origin remains to be fully understood. Our new geochemical study on seamount basalts from the Pukapuka Ridge (PPR) finds a large along-ridge lava compositional variation with a gradual decrease in a geochemically enriched component toward the East Pacific Rise (EPR) axis. This spatial geochemical variation is best understood as resulting from decompression melting of compositionally heterogeneous mantle flowing toward the ridge, where the mantle consists of low-solidus materials of metasomatic origin dispersed within a more refractory peridotite matrix. Far from the ridge axis, preferential melting of enriched lower-solidus materials under thicker lithosphere leaves less enriched residues that undergo further decompression melting as they flow beneath thinner lithosphere toward the ridge axis. This process gives rise to the progressively less enriched lavas along the PPR chain toward the EPR. The residual enriched mantle component became embedded in the mantle beneath the southern EPR (13°S−23°S), forming an along-axis compositional dome at the EPR-PPR intersection (∼17°S−19°S). We predict that nonplume seamounts are best expressed as linear chains near and perpendicular to ocean ridges on fast-spreading plates as long as the flowing mantle is sufficiently heterogeneous. This finding explains widespread seamounts of nonplume origin in the Pacific Ocean, and it also explains the geophysical asymmetries in the mantle electromagnetic tomography (MELT) area.

Kemampuan Mahasiswa PGMI STIT MuhamdiyahBojonegoro Dalam Menyusun Modul Ajar Berbasis Kurikulum Merdeka

Teaching modules are the most important learning tools because they contain learning plans thatwill be implemented by the teacher so that learning is more focused. This research aims todetermine students' abilities in compiling teaching modules based on the Merdeka curriculum.The type of research used is descriptive research using a quantitative approach. The instrumentused is an instrument in the form of a test. In the teaching module there are main components thatmust be implemented. Of these three main components, it was found that students did notunderstand the knowledge about enrichment components and worksheets. The three maincomponents used as benchmarks are general information components, core components, andattachments. There is 1 student who has mastered the teaching module. 3 students who are verygood at making teaching modules, 2 students who are good at mastering making teachingmodules. When preparing teaching modules, students on average have included 3 components intheir modules, although there are still some students who experience several obstacles inpreparing them.

Geochemical and temporal evolution of Indian MORB mantle revealed by the Investigator Ridge in the NE Indian Ocean

The Investigator Ridge, located along the prominent Investigator Fracture Zone in the Wharton Basin, northeast Indian Ocean, was chosen to investigate the temporal and geochemical evolution of the Indian upper mantle. We present new 40Ar/39Ar age, as well as major and trace element and Sr-Nd-Pb-Hf isotope data, from a large part of this so far scarcely sampled ridge. The 40Ar/39Ar ages range from 100.0 Ma to 64.1 Ma, and except for the two youngest samples (65.5 and 64.1 Ma) of likely Christmas Island Seamount Province (CHRISP) origin, display decreasing ages along the ridge from south to north. This pattern is consistent with the ages derived from paleomagnetic anomalies on the local oceanic crust that also decrease in age northwards and suggests an origin of the studied rocks at or near the now extinct Wharton spreading center. These ages also provide information about the displacements along the multiple Investigator Fracture Zones indicating large left-lateral as well as right-lateral offsets of the paleo spreading axis. The fracture zone also shows signs of recent tectonic reactivation. The Investigator Ridge samples are derived from a DUPAL-like mantle source similar to present-day Indian MORB. This source contains a depleted mantle type component, an enriched, moderately HIMU-like, component such as common “C” or “FOZO”, and an additional enriched component of recycled subcontinental lithospheric mantle material. In both the Investigator Ridge and CHRISP samples, the trace element and isotope compositions systematically change with age implying a temporal geochemical evolution of the Indian Mantle Domain in this region. It contained higher proportions of subcontinental lithospheric material delaminated during breakup of Gondwana and mixed with depleted upper mantle material in its early phase. With time, the source evolved in the direction of “C” or “FOZO”, which then became the dominant enriched component and is observed in the youngest samples.

Rhenium–Os isotopic systematics of late Cenozoic intraplate basaltic rocks from Korea: Implications for recycled slab materials in their mantle source

We present, for the first time, comprehensive Re-Os isotopic data for 23 late Cenozoic intraplate basaltic rocks from seven locations (Mount Baekdu, Jeongok, Baengnyeong Island, Ganseong, Ullueng Island, Dok Island, and Jeju Island) on the Korean Peninsula. The Re-Os isotopic system serves as an important tracer of processes such as the reworking of old continental lithosphere or the deep crustal recycling. We use these data to investigate the role of the lithospheric mantle, which is currently debated as a source of the basaltic rocks, and to constrain the source lithology. The initial 187Os/188Os ratios of the Korean basalts range from 0.1321 to 0.6455, with γOs values of 4.0–408.3. The γOs values do not show a simple correlation with Sr-Nd-Hf-Pb isotope compositions. There are no significant correlations between MgO contents and 187Os/188Os ratios or Os contents and 187Os/188Os ratios, which demonstrate that crustal assimilation did not produce the supra-chondritic Os isotopic compositions. The γOs values of the Korean basalts are much higher than previously published γOs of spinel peridotite xenoliths (−9.1 to +1.2) hosted in the basalts, indicating the subcontinental lithospheric mantle was not the main source of the basaltic magmatism. The combination of the Os and Sr-Nd-Hf-Pb isotopic compositions suggests that recycled oceanic crust (potentially Pacific oceanic lithosphere), along with pelagic sediments, which possibly reside in the mantle transition zone, is the enriched component with the supra-chondritic Os isotopic composition in the mantle source of the Korean basalts.

Geochemical characteristics of peridotite xenoliths from the Vitim volcanic field: Insight to late Cenozoic mantle upwelling in SE Siberia

The Vitim volcanic field, comprising Cenozoic basaltic lava flows associated with the Baikal Rift volcanism, contains abundant mantle xenoliths that offer insights into the subcontinental lithospheric mantle (SCLM) beneath the region. This study investigates the mineralogical and geochemical compositions of these mantle xenoliths, entrained in Miocene and Pleistocene basalts. The xenoliths, predominantly garnet-, spinel-, and garnet-spinel-bearing lherzolites, exhibit high modal content of clinopyroxene and low fosterite content of olivine, suggesting a relatively fertile SCLM. Distinct variations in CaO and Al2O3 observed in spongy rims and cores of clinopyroxenes likely result from decompression-induced partial melting. Trace element patterns of clinopyroxene reveal three types: light rare-earth elements (LREE) depleted, LREE enriched, and transitional LREE types. Whole-rock trace element compositions of the four Vitim lherzolites showing flat to LREE and large ion lithophile elements enrichments are entirely consistent with those of their clinopyroxenes. The LREE depleted type indicates that these lherzolites were residual mantle after melt extraction, whereas the LREE enriched type suggests that they were metasomatized after residual mantle formed by partial melting. The transitional LREE type showing in-between features among the above two end-members could represent that those lherzolite underwent less or incomplete metasomatism, thus clinopyroxene cores still retain primary depleted LREE type feature of residual mantle. Most Vitim lherzolites were affected by cryptic metasomatism with less stealth metasomatism, whereas only those with secondary amphibole and apatite could be influenced by modal metasomatism. The lithospheric mantle beath the Vitim volcanic field representing by these lherzolites was metasomatized predominantly by hydrous fluids with minor silicate melts. Using the clinopyroxene melting model, it was found that most Vitim lherzolites have experienced <10% partial melting. Geothermal gradients estimated from mineral geothermobarometry indicate that lherzolites in the Pleistocene basalts equilibrated at shallower depths with higher temperatures compared to those in the Miocene basalts with deeper depths and lower temperatures. SrNd isotopic ratios, combined with previous results (Ionov et al., 2005), demonstrate that the Miocene lherzolites have a broader range from depleted to enriched components, whereas lherzolites in the Pleistocene basalts show lesser enrichment. It is proposed that the Pleistocene basalts captured shallower SCLM lherzolites experienced less degrees of melt metasomatism than those deeper SCLM lherzolites hosted by Miocene basalts. Considering the deeper SCLM is more vulnerable to metasomatism by ascending melts, such temporal and geochemical variation further emphasizes progressive asthenosphere upwelling beneath the Vitim region from the Miocene to Pleistocene time.

The Volcanism of the Meseta del Lago Buenos Aires, Patagonia: the Transition from Subduction to Slab Window

Abstract The Meseta del Lago Buenos Aires (MLBA) in southern Patagonia, a volcanic plateau formed from ~12 Ma to present, provides an opportunity to investigate the temporal evolution in volcanism as this region transitions from the subduction of the Nazca plate to the formation of the slab window produced by the collision of the Chile Ridge and the Andean subduction zone. Here, we report new major, minor, and trace element contents, as well as Sr, Nd, Pb, and Hf isotopes of the MLBA lavas. Three distinct geochemical endmembers can be distinguished in the MLBA basalts: a subduction-influenced endmember, a transitional component similar to the South Atlantic enriched mid-ocean ridge basalts, and an enriched component akin to the EM1 mantle composition. Lavas older than ~1.5 Ma define a compositional continuum between the subduction-influenced and transitional endmembers; this trend is also present in many other southern Patagonian plateaus regardless of their distance to the trench, eruption age, and the composition of the continental blocks where they are located. In contrast, MLBA basalts younger than ~1.5 Ma uniquely define a transition into the EM1 mantle component at the time when this region was affected by the slab window. The estimated pressures and temperatures of mantle-melt equilibration for the MLBA basalts indicates an increase in both parameters after the formation of the slab window that roughly correlate with the changes in lava composition. The basalts’ composition from all southern Patagonia plateaus points to the presence of the South Atlantic mid-ocean ridge basalt mantle influenced by the Discovery, Shona, and Bouvet hotspots rather than the sub-slab mantle, as represented by the Chile Ridge basalts. This observation challenges the hypothesis that the sub-slab mantle within the slab window has had an important role in the composition of the erupted lavas. Instead, it suggests the presence of a South Atlantic mantle beneath southern Patagonia either within the mantle wedge, consistent with a long-lasting South Atlantic convection cell beneath South America, or in the subcontinental lithospheric mantle metasomatized before or just after the opening of the South Atlantic basin, as demonstrated by the composition of southern Patagonia mantle xenoliths. Although it is difficult to precisely distinguish the contributions of the asthenosphere from that of the metasomatized subcontinental lithospheric mantle beneath this region, our work suggests significant contributions from the latter in the composition of the MLBA lavas.

Dual-functional Au-porous anodic alumina (PAA) sensors for enrichment and label-free detection of airborne virus with surface-enhanced Raman scattering

The development of a rapid and sensitive method for the enrichment and direct detection of airborne viruses has become urgently needed to prevent their spread. We have developed a dual-functional, label-free platform for the enrichment and optical identification of airborne viruses. This platform allows for the on-site enrichment and identification of airborne viruses through a virus enrichment component combined with surface-enhanced Raman scattering (SERS). In this work, we created an Au-porous anodic alumina (PAA) composite film, by ion sputtering Au nanoparticles (Au NPs) on a porous structure. The Au-PAA serves as a dual-functional sensor: it combines ultrafiltration through the vertical nanopores in the PAA for virus enrichment and constitutes a plasmonic substrate due to the surface plasmon near-field enhancements within the nanochannel structure. This sensor demonstrates an extraordinary enrichment efficiency (about 98 %) of obtained bioaerosols and enables simultaneous, sensitive detection at the single-virus level. Finite-difference time-domain (FDTD) simulations evidenced the electric field intensity and charge distribution of the Au-PAA. This Au-PAA composite film offers a powerful system for on-site, label-free viral particle enrichment and SERS detection. Contaminated air containing viruses can be collected in a few minutes and analyzed immediately by our platform, which is particularly beneficial for timely monitoring of viruses in the air of large public spaces. Additionally, this platform can be applied to evaluate the indoor air quality.

The role of the sensory input intervention in recovery of the motor function in hypoxic ischemic encephalopathy rat model.

Motor disturbances predominantly characterize hypoxic-ischemic encephalopathy (HIE). Among its intervention methods, environmental enrichment (EE) is strictly considered a form of sensory intervention. However, limited research uses EE as a single sensory input intervention to validate outcomes postintervention. A Sprague-Dawley rat model subjected to left common carotid artery ligation and exposure to oxygen-hypoxic conditions is used in this study. EE was achieved by enhancing the recreational and stress-relief items within the cage, increasing the duration of sunlight, colorful items exposure, and introducing background music. JZL184 (JZL) was administered as neuroprotective drugs. EE was performed 21 days postoperatively and the rats were randomly assigned to the standard environment and EE groups, the two groups were redivided into control, JZL, and vehicle injection subgroups. The Western blotting and behavior test indicated that EE and JZL injections were efficacious in promoting cognitive function in rats following HIE. In addition, the motor function performance in the EE-alone intervention group and the JZL-alone group after HIE was significantly improved compared with the control group. The combined EE and JZL intervention group exhibited even more pronounced improvements in these performances. EE may enhance motor function through sensory input different from the direct neuroprotective effect of pharmacological treatment.NEW & NOTEWORTHY Rarely does literature assess motor function, even though it is common after hypoxia ischemic encephalopathy (HIE). Previously used environmental enrichment (EE) components have not been solely used as sensory inputs. Physical factors were minimized in our study to observe the effects of purely sensory inputs.

OIB-type mafic–ultramafic rocks in South Guangxi, South China: A record of interaction between Paleo-Tethys subduction and Emeishan large Igneous Province

Late Permian ultramafic–mafic igneous rocks in the Pingxiang area, Guangxi, South China include wehrlite, gabbro, diabase, and amygdaloidal basalt. Geochemical characteristics document interaction between the Emeishan Large Igneous Province (ELIP) and the mantle wedge related to subduction of the Paleo–Tethys. Gabbro and basalt show chondrite–normalized rare earth elements (REEs) and primitive mantle–normalized trace element patterns that parallel ocean island basalts (OIB) and mafic intrusions from the ELIP. Melts in equilibrium with clinopyroxenes, in both wehrlite and gabbro, have REEs and trace element compositions similar to OIB and high–Ti mafic rock of the ELIP. The clinopyroxenes also show a rift–related compositional trend and cover those from the ELIP rocks. These compositional features, along with their moderate initial 87Sr/86Sr and εNd(t) values (−0.8 to +3), are consistent with derivation from an enriched mantle plume source. This is the first time that ultramafic–mafic rocks are reported beyond the established extent of the ELIP and could represent an offshoot from the main mantle plume or indicate that the ELIP plume was considerably bigger than current proposals but has been significantly denuded by subsequent erosion. In addition, the Pingxiang rock units display slightly enriched εNd(t) values and slight negative Nb, Ta, and Zr relative to OIB rocks, indicating an enriched component in the mantle source. Formation of the ELIP spatially and temporally overlapped with subduction of the Paleo–Tethys ocean and interaction between the plume and mantle wedge accounts for the compositional diversity of the ELIP. Such interaction is probably common along the southwestern–southern margin of the Yangtze Block.

Extremely enriched lithospheric mantle–derived magmas in the central Lhasa Terrane, southern Tibet

ABSTRACT Plate tectonics plays a crucial role in the evolution of Earth’s continents and oceans. However, the impact of oceanic subduction and continental collision on the continental lithospheric mantle within collisional orogenic belts is still a matter of debate. To address this issue, we performed a thorough analysis of mafic rocks in the Nixiong area within the central Lhasa Terrane, southern Tibet. The mafic rocks are composed of diabases and basalts formed during syn-collisional period (~50 Ma). The diabases have low SiO2 and moderate MgO contents, and are enriched in large ion lithophile elements and depleted in high field strength elements. They show high 87Sr/86Sri (0.711451–0.712084) and low εNd(t) (−7.9 to −6.44), as well as enriched Hf-Pb isotope compositions (εHf(t) = -7.58 to −6.59; 206Pb/204Pbi = 18.59–18.71; 207Pb/204Pbi = 15.71–15.72; 208Pb/204Pbi = 39.33–39.53). Geochemical modelling suggests that the diabases were formed through the partial melting of peridotite at high temperatures and shallow depths, with significant addition of subduction-related components to the primary melts. The diabases probably originated from a metasomatized lithospheric mantle due to subduction of Neo-Tethyan slab. The basalts display similar SiO2 but lower MgO contents compare with the diabases. They are also characterized by extremely high 87Sr/86Sri (0.713332–0.713448), low εNd(t) (−10.32 to −9.96), and significantly enriched Hf-Pb isotope compositions (εHf(t) = -12.30 to −12.05; 206Pb/204Pbi = 18.81–18.85; 207Pb/204Pbi = 15.74–15.75; 208Pb/204Pbi = 39.81–39.88), corresponding to an extremely enriched lithospheric mantle. Integrated with the previous studies, the Nixiong mafic rocks exhibit the most enriched isotopic compositions among the arc- or syn-collision-related mafic rocks in southern Tibet. These extremely isotopically enriched components were most likely derived from the ancient continental lithospheric mantle beneath the central Lhasa Terrane. Our results provided unambiguous evidence that the pre-existing ancient continental lithospheric mantle could persist locally during the prolonged oceanic subduction and subsequent continental collision.

Seaweed as a functional ingredient and emulsifier in dairy processing

In response to customer demand for a balanced and healthful diet, there is a growing trend in manufacturing innovative dairy products enhanced with plant ingredients with particular pharmacological qualities. Yoghurt is a dairy product that is becoming increasingly popular among consumers since it is a great way to absorb functional food elements like probiotics, prebiotics, and antioxidants. It’s critical to increase public awareness of the health hazards associated with yoghurt use in addition to adding affordable, nutrient-dense functional additives to Yoghurt. Due to their high nutritional content and potential health benefits, algae have long been utilized as a food source. However, rising interest is in using them as enrichment components in manufacturing new foods. Consequently, this paper draws attention to the potential of Seaweed in manufacturing yoghurt, as shown in current scientific literature. However, more research needs to be done on adding seaweed components to Yoghurt, which is considered safe for human ingestion and has undergone clinical testing. We hope this study will raise awareness about the need for more research to address the growing demand for Yoghurt.

Sr–Nd Isotopic Evidence of a Heterogeneous Magmatic Source of Alkaline–Carbonatite Rocks of the Odikhincha Alkaline–Carbonatite Massif (Maimecha-Kotui Province, Siberia)

This study focuses on the igneous rocks composing the Odikhincha massif. The massif is typical ring alkaline–ultrabasic massif with carbonatites, second largest in the Maimecha-Kotui province. The Sr-Nd isotopic values of the traps of the Arydzhang Formation and the host dolomites were also determined for comparison. The Rb–Sr isotope system of phlogopite and calcite from the Od-16-19 carbonatite of the Odikhincha massif is disturbed; the obtained age on the mineral isochrone (245 ± 3 Ma) is close to the time of formation of the Siberian traps and rocks of the ultrabasic–alkaline Maimecha-Kotui complex, but the large scatter of analytical points (MSWD = 22) does not allow this date to be considered as reliable. The disturbance of the isotope system is probably related to the fact that the strontium isotope ratio in the fluid was not constant during autometasomatic phlogopitization of carbonatite. The U–Pb isotopic system of titanite and perovskite from the same carbonatite sample Od-16-19 also appeared to be disturbed, since data points formed discordia. The U–Pb age obtained for titanite and perovskite are 244 ± 5 Ma (MSWD = 1.8) and 247 ± 18 Ma (MSWD = 4), respectively. Apparently, the age values provided by the two isotopic systems (245 ± 3 Ma by Rb–Sr and 247 ± 18 and 244 ± 5 Ma by U–Pb) are consistent with each other and reflect the time of metasomatic processes, i.e., phlogopitization and iolitization. Rb–Sr and Sm–Nd isotope data for ultrabasic–alkaline intrusive rocks with carbonatites of the Odikhincha massif and volcanics of the Arydzhang Formation indicate an enriched, relative to the composition of the convecting mantle, isotopically heterogeneous source of their parent melts. This source could be a combination of ultrabasic mantle rocks and rocks of basic composition (basites). The latter played the role of an enriched component. No signs of contamination of the melts with the host sedimentary rocks in situ were found, however, variations of Sr and Nd isotopic ratios in the rocks of the Odikhincha massif may indicate that during the introduction of deep magmas their interaction and substance exchange with the surrounding rocks of the lithosphere continued up to complete solidification of the melts, as indicated by the nature of local isotopic heterogeneity within the Odikhincha intrusion.

Sr–Nd Isotopic Evidence of a Heterogeneous Magmatic Source of Alkaline–Carbonatite Rocks of the Odikhincha Alkaline–Carbonatite Massif (Maimecha-Kotui Province, Siberia)

This study focuses on the igneous rocks composing the Odikhincha massif. The massif is typical ring alkaline–ultrabasic massif with carbonatites, second largest in the Maimecha-Kotui province. The Sr-Nd isotopic values of the traps of the Arydzhang Formation and the host dolomites were also determined for comparison. The Rb–Sr isotope system of phlogopite and calcite from the Od-16-19 carbonatite of the Odikhincha massif is disturbed; the obtained age on the mineral isochrone (245 ± 3 Ma) is close to the time of formation of the Siberian traps and rocks of the ultrabasic–alkaline Maimecha-Kotui complex, but the large scatter of analytical points (MSWD = 22) does not allow this date to be considered as reliable. The disturbance of the isotope system is probably related to the fact that the strontium isotope ratio in the fluid was not constant during autometasomatic phlogopitization of carbonatite. The U–Pb isotopic system of titanite and perovskite from the same carbonatite sample Od-16-19 also appeared to be disturbed, since data points formed discordia. The U–Pb age obtained for titanite and perovskite are 244 ± 5 Ma (MSWD = 1.8) and 247 ± 18 Ma (MSWD = 4), respectively. Apparently, the age values provided by the two isotopic systems (245 ± 3 Ma by Rb–Sr and 247 ± 18 and 244 ± 5 Ma by U–Pb) are consistent with each other and reflect the time of metasomatic processes, i.e., phlogopitization and iolitization. Rb–Sr and Sm–Nd isotope data for ultrabasic–alkaline intrusive rocks with carbonatites of the Odikhincha massif and volcanics of the Arydzhang Formation indicate an enriched, relative to the composition of the convecting mantle, isotopically heterogeneous source of their parent melts. This source could be a combination of ultrabasic mantle rocks and rocks of basic composition (basites). The latter played the role of an enriched component. No signs of contamination of the melts with the host sedimentary rocks in situ were found, however, variations of Sr and Nd isotopic ratios in the rocks of the Odikhincha massif may indicate that during the introduction of deep magmas their interaction and substance exchange with the surrounding rocks of the lithosphere continued up to complete solidification of the melts, as indicated by the nature of local isotopic heterogeneity within the Odikhincha intrusion.

Metasomatized mantle source of nascent oceanic crust in the Guaymas Basin, Gulf of California

The geochemical characteristics of nascent oceanic crust play a crucial role in unraveling the mantle dynamics of the initial opening of an ocean. The Gulf of California, located at the East Pacific margin, is one of the best examples of an active and obliquely rifted continental margin. However, the mantle source composition of the nascent oceanic crust in the central part of the Gulf has not yet been comprehensively investigated. Here, we report in situ major and trace element contents as well as BSr isotope compositions for basaltic glass samples from off-axis sills drilled by the International Ocean Discovery Program (IODP) Expedition 385 at Sites U1547 and U1548 in the Guaymas Basin in the central part of the Gulf of California. These glassy samples represent tholeiites and predominantly show trace element patterns akin to those of enriched mid-ocean ridge basalts (E-MORBs) but with distinctive enrichments in Ba and K and depletions in Nb, Ta, and Ti. In addition, these samples have high B contents (3.07–3.67 ppm) with enriched Sr isotopes (87Sr/86Sr = 0.7032–0.7037) and heavy B isotopes (δ11B = −5.52‰ to 1.20‰). The mixing model based on B/Nb values and SrB isotopes shows that the nascent oceanic crust in the Guaymas Basin might be generated through partial melting of a depleted MORB mantle (DMM) source metasomatized by melts from subducted slab materials referring to partially dehydrated sediment and altered oceanic crust components. The magmas in the Gulf of California show a systematic decline in their enrichment in fluid-mobile elements (Ba) and depletion in fluid-immobile elements (Nb, Ta, and Ti) from the northern (e.g., Isla San Luis volcanic center) to the central part (Guaymas Basin) and southward to the mouth (e.g., Alarcón Basin) of the Gulf. This suggests that the enriched (recycled) components in their mantle source were gradually extracted and exhausted during Gulf opening and oceanic crustal accretion that advanced in a northward direction. Our results indicate that the Guaymas Basin magmas were derived from a mantle that was fertilized by subduction components. The subduction signature corroborates the Gulf opening as a process that started in response to long-term oblique convergence at the eastern Pacific plate margin without any influence from a mantle plume. This evolution is different from nascent ocean basins that evolved from intraplate rifting, such as the Red Sea, leading to vastly different mantle source characteristics.

Early Eocene Arctic volcanism from carbonate-metasomatized mantle

Melilitite, nephelinite, basanite, and alkali basalt, along with phonolite differentiates, form the Freemans Cove Complex (FCC) in the south-eastern extremity of Bathurst Island (Nunavut, Canada). New 40Ar/39Ar chronology indicates their emplacement between ~ 56 and ~ 54 million years ago within a localized extensional structure. Melilitites and nephelinites, along with phonolite differentiates, likely relate to the beginning and end phases of extension, whereas alkali basalts were emplaced during a main extensional episode at ~ 55 Ma. The melilitites, nephelinites, and alkali basalts show no strong evidence for significant assimilation of crust, in contrast to some phonolites. Partial melting occurred within both the garnet- and spinel-facies mantle and sampled sources with He, O, Nd, Hf, and Os isotope characteristics indicative of peridotite with two distinct components. The first, expressed in higher degree partial melts, represents a relatively depleted component (“A”; 3He/4He ~ 8 RA, εNdi ~ + 3 εHfi ~ + 7, γOsi ~ 0). The second was an enriched component (“B” 3He/4He < 3 RA, εNdi < – 1 εHfi < + 3, γOsi > + 70) sampled by the lowest degree partial melts and represents carbonate-metasomatized peridotite. Magmatism in the FCC shows that rifting extended from the Labrador Sea to Bathurst Island and reached a zenith at ~ 55 Ma, during the Eurekan orogeny. The incompatible trace-element abundances and isotopic signatures of FCC rocks indicate melt generation occurred at the base of relatively thin lithosphere at the margin of a thick craton, with no mantle plume influence. FCC melt compositions are distinct from other continental rift magmatic provinces worldwide, and their metasomatized mantle source was plausibly formed synchronously with emplacement of Cretaceous kimberlites. The FCC illustrates that the range of isotopic compositions preserved in continental rift magmas are likely to be dominated by temporal changes in the extent of partial melting, as well as by the timing and degree of metasomatism recorded in the underlying continental lithosphere.

Zircon double-dating, trace element and O isotope analysis to decipher late Pleistocene explosive-effusive eruptions from a zoned ocean-island magma system, Ascension Island

In this first detailed study of zircon from Ascension Island, South Atlantic, we take a novel approach combining trace element and O isotope compositional data with double-dating (disequilibrium 238U–230Th and (U–Th)/He) to decipher timescales and dynamics of magmatic processes. The Echo Canyon (EC) sequence comprises small-volume explosive-effusive eruptions of trachyte that tapped a compositionally zoned magma system. Associated volcanic hazards may be constrained from the age of volcanism, duration of magma storage, and magma source and plumbing system character. Zircon U–Th–Pb dating of lithic lava clasts has revealed recurrent evolved volcanism at 1.34 and 0.6 Ma, and 95 ka. The (U–Th)/He zircon cooling ages indicate that most of the EC explosive-effusive sequence erupted in a brief episode at ca. 95 ka. Additionally, uniform 238U–230Th zircon crystallisation ages suggest moderately protracted magma storage with melt present at depth for at most 103–104 years before eruption. The enriched character of zircon trace element compositions, relative to MORB, in the absence of a continental crustal signature in the oxygen isotope values (δ18O range 2.67–5.63‰), suggests the presence of an enriched component in the EC magma source. Furthermore, low δ18O zircon compositions imply assimilation of high temperature hydrothermally altered country rock by the source magma. The mineral assemblage in crystal-poor pumices indicates equilibrium storage conditions: zircon saturation and Ti-in-zircon crystallisation temperatures are consistent with alkali feldspar-melt temperatures. Significantly, zircon crystals were preserved both as macrocryst inclusions and in the groundmass of EC explosive and effusive deposits. These rocks preserve evidence of magma evolution by fractional crystallisation. This process led to pre-eruptive compositional stratification, which is evidenced in the range of whole-rock major and trace element compositions and zircon Zr/Hf values. Notably, zircon crystallisation and cooling ages derived from pumice, lava, and accidental lithic lava clasts in highly explosive pyroclastic deposits, have revealed episodes of evolved magmatism that would otherwise have gone undetected. In addition, the zircon trace element and isotope compositions, in combination with the range of crystallisation ages, evidence progressively deeper tapping of less evolved magma stored in discrete lenses. Thus, a combined zircon geochronological-geochemical approach can place constraints on the ca. 0.6 Ma recurrence of past explosive-effusive pulses of millennial to decamillennial duration and their enriched magma sources. This information is relevant for assessing hazards and informing monitoring and forecasting efforts to assist in managing associated risks for small ocean island volcanoes with particularly vulnerable populations and infrastructure.

Enlarged housing space and increased spatial complexity enhance hippocampal neurogenesis but do not increase physical activity in mice.

Environmental enrichment (EE) improves various health outcomes, such as hippocampal neurogenesis, in rodents, which is thought to be caused, in part, by increased physical activity. However, the specific effect of each enrichment component, such as enlarged housing spaces and increased spatial complexity with a variety of objects, on physical activity remains unclear because of methodological limitations in measuring physical activity. We aimed to examine whether enlarged housing spaces and increased spatial complexity increase physical activity in mice using a body-implantable actimeter. Adult male C57BL/6J mice were assigned to either standard housing or EE groups. The housing environment in the EE mice was gradually enriched by enlarging the housing space and the placement of a variety of objects. Physical activity was measured using a body-implanted actimeter. Hippocampal neurogenesis was immunohistochemically examined. Enlarged housing spaces and the placement of a variety of objects did not increase physical activity in mice. In contrast, hippocampal neurogenesis was enhanced in the EE mice, suggesting that environmental interventions successfully provided enriched housing conditions for these mice. These results indicate that enlarged housing spaces and increased spatial complexity do not increase physical activity in mice. Furthermore, we found that EE enhanced hippocampal neurogenesis without increasing activity volume. Besides the current understanding that increasing the amount of physical activity is key to improving hippocampal function, our result suggests that the environment in which physical activity takes place is also a crucial contextual factor in determining the impact of physical activity on hippocampal function.

Development of a technology for the production of germinated flaxseed using plasma-chemically activated aqueous solutions

The result of the research is the development of a technology for the production of germinated flaxseed using plasma-chemically activated aqueous solutions. The object of research was flaxseed. An urgent technological problem is the intensification of the bioactivation process of flaxseed and its effective disinfection. The expediency of using plasma-chemically activated aqueous solutions as an intensifier of the process of flaxseed germination and an effective disinfectant of food raw materials was experimentally proven. It is shown that the use of plasma-chemical activation of process solutions not only accelerates flaxseed germination, but also contributes to a more active accumulation of biologically valuable components in flax raw materials. The composition of flaxseed as a raw material derivative was analyzed. Germinated flaxseed, which is considered a high-value component of food products, was studied separately. An increase in the moisture content of flaxseed during the soaking process by 0.7–1.7 % was recorded. Seedling development increases by 2–9 mm. The germination energy and capacity increase by 5–12 %. The biomass of germinated seeds increases by 39–56 %. In the process of germination, the content of proteins in flaxseed increases from 21.88 to 23.71 %, reducing sugars from 2.37 to 4.02 %. The total content of amino acids increases from 3.64 to 10.38 % compared to the control, and 10 times compared to the raw material. A significant accumulation of vitamins was noted: B1, B2, B3, B5, B6, B7, B9, C, E. In addition, plasma-chemically activated solutions effectively disinfect germinated flaxseed. The technology can be applied in the production of enrichment components of food products. The developed technology will receive special attention in the production of functional food products

Geochemistry, petrology, and isotopic characteristics of the Enseada da Caieira intrusions: Insights from mineral chemistry and Nd and Sr isotopes from Fernando de Noronha, South Atlantic, Brazil

The alkaline magmatism found in the Brazilian Equatorial Margin (BEM) in the Southwest Atlantic Ocean, such as that observed in Fernando de Noronha Archipelago, poses intriguing questions about its origin and its relationship to guyots and onshore magmatism of similar alkaline compositions in northeast Brazil. The Fernando de Noronha Archipelago (FNA) exhibits a broad spectrum of alkaline magmatism, ranging from foiditic to phonolitic/trachytic compositions. At the Enseada da Caieira, a group of intrusions reflects this wide variety from FNA. This paper presents a complete description of these intrusions based on petrography, lithogeochemistry, and mineral and isotopic chemistry, as well as thermobarometry and petrogenetic modeling. The new data are compared with data compiled from the FNA, BEM onshore and offshore magmatism, and the Vitória-Trindade Ridge (VTR). The intrusions are classified as trachyte, alkali-basalt/basanite, phonotephrite, and picrobasalt. The compositional diversity of dikes outcropping in a relatively small area suggests a complex petrogenetic evolution for the feeding system of the Fernando de Noronha Island. This is supported by the presence of porphyritic clinopyroxenes (for example) with compositional zoning, indicating multistage crystallization processes. Flow, resorption, and glomeroporphyritic textures are common. Skeletal crystals also occur as phenocrysts of olivine and clinopyroxene due to supercooling. Secondary minerals such as zeolites and carbonate commonly occur as fillers in amygdules. Values for ƐNd range from +0.2 to +3.1. The Sr–Nd isotopic signatures suggest a mixture between an enriched component (EMII) and a depleted mantle component (DMM). A multi-approach thermobarometer using clinopyroxene, amphibole, and zircon mineral chemistry reveals different stages for crystallization, with pressure and temperature ranging from 320 to 1300 MPa and 750 to 1240 °C, respectively. The whole-rock lithogeochemistry modeling suggests a low degree of partial melting (around 2% or less) of an enriched source with variable proportions from spinel and garnet-lherzolite melting zones.

Hydrothermal circulation at 1.8 Ga in the Kiruna area, northern Sweden, as revealed by apatite geochemical systematics

The Kiruna area in northern Sweden hosts the classic Kiruna iron-oxide-apatite (IOA) deposit. The area has experienced complex tectonic processes, including basin formation, inversion, and hydraulic fracturing events from ∼1.9 Ga and possibly down to ∼1.5 Ga. However, the nature, timing and links of hydrothermal events related to this tectono-thermal evolution are unclear, impairing our full understanding of IOA formation processes. Here, we use multiple analytical methods to study apatite from the Kiirunavaara orebody. Electron microscopy, cathodoluminescence images, and rare earth element contents of the studied apatite indicate alteration by hydrothermal fluids. U-Pb Tera-Wasserburg lower intercept age of the altered apatite is 1800 ± 36 Ma, indicating a contemporaneous hydrothermal event in the central Kiruna area during coeval basin inversion. Sr isotopes obtained in these altered apatites, ranging from 0.709 to 0.713, may represent intermediate Sr isotope values between primary apatite and secondary fluid resetting. The relatively high but scattered 87Sr/86Sr ratios suggest that country rocks of the IOA deposits and other regional intermediate-felsic igneous rocks with old or enriched components are most likely the source of the fluids. Previous studies have revealed two hydrothermal events in the IOA ores at roughly 1.73 Ga and 1.63 Ga. Thus, fluids sourced from the host rocks of the regional IOA deposits and regional granitoids have circulated episodically at 1.80 Ga, 1.73 Ga, 1.63 Ga and possibly 1.5 Ga in the Kiruna area and have partly redistributed rare earth elements formed during the primary 1.88 Ga IOA formation event.