Rb Concentrations Research Articles

Tracing the Scale of Fluid Flow in Subduction Zone Forearcs: Implications from Fluid-Mobile elements

Despite the importance of fluids in subduction zone processes, the extent of mass transfer and fluid circulation from the subducting plate through the forearc region remain unclear. To estimate the fluid budget and scale of fluid circulation in subducted sediments, we assess the distribution and retention of fluid-mobile elements (FME) in metamorphically equivalent metapelites from the Kodiak complex (Alaska) and the Shimanto Belt (Japan). The temperature range of interest is 230–350 °C, i.e., encompasses the base of the seismogenic zone. We examine the Li, B, Rb, Sr, Cs, and Ba concentrations in the bulk rock, as well as in fluid inclusions and individual minerals by (LA-) ICP-MS.The whole-rock composition in metapelites from Kodiak shows no significant loss of FME, which is in contrast to Shimanto where between 10% and 55% of FME (particularly Li, B and Cs) are leached out of rocks. The FME budget in Kodiak is consistent with a redistribution of elements between metamorphic illite and chlorite, whereas in Shimanto the loss of Li, B and Cs as temperature increases is the result of decreasing concentrations in illite and chlorite. The semi-quantitative analysis of fluid inclusions is consistent with a significant enrichment in all analyzed trace elements relative to seawater and interstitial pore fluids of seafloor sediments.Combining the fluid compositions with the whole-rock compositions, mass balance calculations were performed for B, Cs, and Ba. In the Kodiak complex the mass balance calculations are consistent with closed-system behavior, wherein the fluid is an insignificant reservoir for FME. Conversely, in the Shimanto Belt the mass balance calculations are consistent with open-system behavior, wherein large amounts of fluid percolated through rocks and the mass water-rock ratios correspond to 0.5–2.2. We infer that such an open system behavior was promoted by a larger amount of internal strain and the proximity to a large-scale fault zone. Moreover, fluid compositions observed in this study exhibit similarities to the composition of mud volcano fluids. This similarity is consistent with extensive, focused fluid circulation originating from depths of at least 15 km and ascending to the surface through a substantial damage zone associated with an out-of-sequence thrust.

Associations between maternal exposure to multiple metals and metalloids and blood pressure in preschool children: A mixture-based approach

BackgroundExposure to metals during pregnancy can potentially influence blood pressure (BP) in children, but few studies have examined the mixed effects of prenatal metal exposure on childhood BP. We aimed to assess the individual and combined effects of prenatal metal and metalloid exposure on BP in preschool children. MethodsA total of 217 mother–child pairs were selected from the Zhuang Birth Cohort in Guangxi, China. The maternal plasma concentrations of 20 metals [e.g. lead (Pb), rubidium (Rb), cesium (Cs), and zinc (Zn)] in early pregnancy were measured by inductively coupled plasmamass spectrometry. Childhood BP was measured in August 2021. The effects of prenatal metal exposure on childhood BP were explored by generalized linear models, restricted cubic spline and Bayesian kernel machine regression (BKMR) models. ResultsIn total children, each unit increase in the log10-transformed maternal Rb concentration was associated with a 10.82-mmHg decrease (95% CI: −19.40, −2.24) in childhood diastolic BP (DBP), and each unit increase in the log10-transformed maternal Cs and Zn concentrations was associated with a 9.67-mmHg (95% CI: −16.72, −2.61) and 4.37-mmHg (95% CI: −8.68, −0.062) decrease in childhood pulse pressure (PP), respectively. The log10-transformed Rb and Cs concentrations were linearly related to DBP (P nonlinear=0.603) and PP (P nonlinear=0.962), respectively. Furthermore, an inverse association was observed between the log10-transformed Cs concentration and PP (β =-12.18; 95% CI: −22.82, −1.54) in girls, and between the log10-transformed Rb concentration and DBP (β =-12.54; 95% CI: −23.87, −1.21) in boys, while there was an increasing association between the log10-transformed Pb concentration and DBP there was an increasing in boys (β =6.06; 95% CI: 0.36, 11.77). Additionally, a U-shaped relationship was observed between the log10-transformed Pb concentration and SBP (P nonlinear=0.015) and DBP (P nonlinear=0.041) in boys. Although there was no statistically signiffcant difference, there was an inverse trend in the combined effect of maternal metal mixture exposure on childhood BP among both the total children and girls in BKMR. ConclusionsPrenatal exposure to both individual and mixtures of metals and metalloids influences BP in preschool children, potentially leading to nonlinear and sex-specific effects.

Petrology and Geochemistry of an Unusual Granulite Facies Xenolith of the Late Oligocene Post-Obduction Koum Granodiorite (New Caledonia, Southwest Pacific): Geodynamic Inferences

Pressure–temperature estimates of a xenolith found within a post-obduction granodiorite in southern New Caledonia provide evidence for subcrustal, granulite facies, peak crystallisation conditions (ca. 850 °C—8.5 ± 1.0 kbar), followed by isobaric cooling to 700 °C, and final decompression with partial rehydration at ca. 650 °C—3.5 kbar. The xenolith, dated at 24.7 Ma (U-Pb zircon), i.e., the same age as the granodiorite host rock, has low SiO2 (35.5 wt%) and high Al2O3 (33.2 wt%) contents, suggesting that it is the restite of a previous melting episode, while the elevated Ca (Ba and Sr) contents suggest mantle metasomatism. Although the concentrations of Rb, K, Ca, Ba, and Sr have been strongly modified, some geochemical (REE patterns and some “immobile” trace element ratios) and isotopic (Sr and Nd isotopic ratios, U-Pb zircon age) characteristics of the granulite facies xenolith are similar to those of the xenoliths found in other Late Oligocene intrusions in southern New Caledonia; therefore, this rock is interpreted to be related to an early magmatic episode. The rock protolith was emplaced and equilibrated at the base of the crust where it underwent ductile deformation. Younger ascending magma picked it up and they eventually crystallised together at a shallow crustal level, near the tectonic sole of the ophiolite. The recrystallisation and ductile deformation at ~8.5 kbar suggest that a rheological discontinuity existed at about 25–28 km, probably representing the Moho. It is concluded that a continental crust of normal thickness must have existed beneath New Caledonia at about 24 Ma, i.e., 10 Ma after obduction.

Unravelling the effects of magmatic fractionation, fluid phase separation and dilution on the composition of magmatic-hydrothermal fluids of the Cornubian Batholith (SW England)

The compositional evolution of magmatic-hydrothermal fluids from the SnW mineralized Cornubian batholith was investigated via in situ fluid inclusion LA-ICP-MS microanalysis and reveals a large degree of variation between intrusive stages and at the sample scale, with complexities due to superposition of several mechanisms affecting fluids chemistry during the protracted evolution of the batholith. Despite large ranges of salinities (from <1 wt% to 48 wt% NaCleq.), the effects of individual processes such as magmatic differentiation, fluid saturation and boiling, fluid mixing and dilution can all be discerned on the basis of fluid inclusion trace element geochemistry combined with detailed petrography and microthermometry.In all samples, different fluid types (aqueous liquid-rich, vapor-rich and brine inclusions) were identified in variable proportions and microthermometry revealed complex temporal trends. Granite-related samples from the G5 intrusive stage are characterized by intermediate density fluids undergoing magmatic fractionation under pressure conditions above 1.5 kbar, indicated by successively decreasing fluid salinities with concomitant increases in Li, B, Rb and Cs concentrations. The latter two elements later strongly partitioned in the brine phase upon boiling, together with most of the other Cl-complexing elements (e.g., Fe, Mn, Pb, Zn). Those brines subsequently underwent progressive dilution with meteoric waters that caused a decrease in the concentration of all elements (besides B) and homogenization temperatures. In G3 granite from Dartmoor, on the other hand, brine inclusions represent the earliest fluid type while intermediate density fluids are absent, and a large salinity range in the fluid inclusion record associated with a decrease in homogenization temperatures represents their progressive dilution with meteoric fluid. The lack of intermediate density fluids at Dartmoor indicates fluid exsolution at relatively low pressures resulting in immediate phase separation into brine and vapor.All studied samples associated with ore mineralization display only the trend of dilution of high-salinity magmatic fluids. Their transition metal contents (e.g. Fe, Mn, Pb and Zn) show the expected positive correlation with salinity of the fluids. Conversely, the compositional trends observed for Sn and particularly W are more enigmatic, as they do not appear to significantly fractionate during most of the physicochemical processes outlined above and appear to be unrelated to fluid salinity, opposite of what would be expected for Sn as it is dominantly transported in Cl-complexes.This study highlights the key advantages of high-resolution geochemical fluid inclusion studies in discerning a variety of magmatic and post-magmatic processes in fluids in comparison to bulk fluid inclusion techniques or more simplistic fluid inclusions studies which might overlook important aspects of the typically complex history of fluids evolution in magmatic-hydrothermal systems.

Authentication of selected white wines by geographical origin using ICP spectrometric and chemometric analysis

An important aspect of assessing the authenticity of wines is its geographical origin. The aim of the work is to authenticate by geographical origin according to the data of the ICP-spectrometric and chemometric analysis of elemental "images" of wines produced from white grape varieties Chardonnay, Riesling and Muscat grown in four regions of the Krasnodar Territory, Russia. The difference in the contents of Al, Ba, Ca and Rb in wines was found depending on the variety, and Al, Ba, Rb, Fe, Li, Sr – depending on the region of grape growth. Different models of the experimental data processing were used for attribution of the produced varieties of wine to the area of the grape's growth. The criterion for the quality of the constructed models was the accuracy of the attribution of a wine variety to the area of the grape's growth (%). Analysis of the elemental analysis data of 153 wine samples showed that in terms of attribution accuracy, automated neural networks (100 %) are preferred among machine learning methods, followed by support vector machines (98.69 %) and general discriminant analysis (94.77 %). The applied mathematical models enabled the revealing of the cluster structure of the analyzed wine varieties and their attribution to the area of a grape growth with high accuracy. Sr, Li and Fe concentrations in wines were found as the dominating predictors in the constructed models for definition of the geographical origin of wines. The combination of ICP-spectrometric analysis data with the capabilities of statistical modeling of machine learning methods focused on large-dimensional data made it possible to successfully solve small-dimensional problems of the definition of the geographical origin of wines by their elemental composition and variety.

Association between trace element contents in normal human breast and age investigated using inductively coupled plasma mass spectrometry

The etiology of breast cancer remains largely unclear; however, it is well known that the incidence of this disease increases with age. In the presented work, for the first time, the age-related changes of Al, As, B, Ba, Bi, Cd, Ce, Cr, Cu, La, Li, Mg, Mn, Nb, Ni, Pb, Rb, Sb, Sn, Sr, Ti, W, and Zn content in the mammary gland of women aged 16-60 years was investigated. For this purpose, a method based on inductively coupled plasma mass spectrometry (ICP-MS) was employed, which makes it possible to determine the mass fractions of these trace elements in microsamples (mass from 10 mg) of breast tissue. With the help of this method, the material obtained during the autopsy of 38 practically healthy women aged 16-60 years who died suddenly was studied. Trace element mass fractions were determined in two age groups of women: 16-40 and 41-60 years old. Using the parametric Student's t-test and the non-parametric Wilcoxon-Mann-Whitney U-test to compare two age groups, as well as Pearson's correlation coefficients between age and trace elements mass fractions, it was found that the Cu, Mg, Rb, and Zn mass fractions in normal breast tissue decrease with age, while the As mass fraction increase. The phenomenon of the age-related changes of trace elements mass fractions in the normal mammary gland, discovered for the first time, requires further detailed study.

Process Mineralogy of Lithium and Rubidium in the Diantan Polymetallic Mining Area, Tengchong, Southwest China

Highly differentiated granite often contains abundant key metal resources, such as lithium and rubidium. The Tengchong area of Yunnan hosts a large number of highly differentiated granites from the Cretaceous age. Among these, granite samples from the Diantan tin–lead–zinc polymetallic mining area exhibit Li contents exceeding 0.02% and Rb contents surpassing 0.1%. This suggests a promising potential for Li and Rb mineralization. However, the occurrence status and process mineralogical characteristics of Li and Rb remain unclear, directly impacting the assessment of the region’s comprehensive utilization potential for these key metals. This study focuses on representative granite samples from the Diantan mining area to conduct petrographic and process mineralogical research, examining single mineral chemical composition, physical properties, element occurrence state, and mineral embedding particle size. The results indicate that mica minerals primarily contain Li, while both feldspar and mica minerals are the main carriers of Rb. Zinnwaldite not only contains the highest Rb proportion among the samples but also plays a significant role in Li occurrence. Based on the dissociation characteristics, it is recommended to grind the material to a fineness of −0.075 mm, comprising 80% of the particles, before proceeding to the final flotation process. This would result in approximately 95% dissociation of the mica in the sample. Since mica is predominantly distributed between quartz and feldspar particles, with relatively low binding force, it facilitates mineral dissociation during the grinding process. Therefore, the actual beneficiation process may consider a moderately coarser grinding fineness based on the aforementioned findings.

Mineralogy and 40Ar-39Ar dating of the recently discovered tainiolite occurrences in the Kaerqiaer fluorite Belt, western Altyn Tagh Terrane

The Kaerqiaer Fluorite Belt (KFB) contains the Kaerqiaer, Xiaobaihegou, Kumutashi, Northern Layidan, and Gaijike fluorite deposits in the western Altyn Tagh Terrane of NW China. An occurrence of Li-bearing mica tainiolite (KLiMg2(Si4O10) F2) has been recently discovered, associated with fluorite-bearing alkali feldspar granite. The tainiolite is hosted by fluorite-calcite veins that contain assemblages of tainiolite-fluorite-calcite and apatite-bastnaesite-tainiolite-fluorite-calcite along the contact zone with alkali feldspar granite. The tainiolite occurs as euhedral crystals and has high concentrations in the veins. 40Ar-39Ar dating of the tainiolite from Xiaobaihegou yields an age of 421 ± 2 Ma, and single-crystal X-ray diffraction confirms the tainiolite has a monoclinic 1 M−type with a C2/m (#12) space group. Minor structural variations in the mica are attributed to the substitution of Li for Mg. EPMA and LA-ICP-MS analyses show that the tainiolite has high Li, Rb, Cs, Sn and Nb concentrations, and low Ta, total REE concentrations. The average Li2O content of the fluorite-tainiolite veins reaches 0.36 %, surpassing the economic cut-off grade. We suggest that the fluorite deposits formed from highly fractionated Li-F-P-rich residual melt evolved from the parental magmas of alkali feldspar granite. The tainiolite mineralisation may result from subsequent hydrothermal activities caused by the reactivation of regional faults under the extensional regime between the Middle Altyn and Eastern Kunlun terranes. The discovery of tainiolite occurrences made KFB a potential area for not only F but also Li resources.

Rb, Sr, Sm and Nd elemental concentrations and Sr and Nd isotopic ratios of 13 Chinese rock reference materials using isotope dilution TIMS and MC–ICP–MS

The suitability of 13 Chinese silicate rock certified reference materials for Sr and Nd isotope analyses was investigated. To indicate their homogeneity and to provide information values, we report Sr and Nd isotopic data and Rb, Sr, Sm and Nd concentrations for reference materials GBW07 103–105, 109–113 and 121–125 spanning a broad compositional range. Test portions were spiked with tracers enriched in 87Rb–84Sr and 149Sm–145,146,150Nd and digested using HF, HNO3, and HClO4 acid-dissolution procedures. Chemical purification involved cation-exchange and HEHEHP or Ln resins. Analyses involved different instruments at four laboratories, including thermal ionisation mass spectrometry (TIMS) and multicollector–inductively coupled plasma–mass spectrometry (MC–ICP–MS). This study provides a comprehensive report of the Rb–Sr and Sm–Nd isotopic compositions of the reference materials, and the results indicate that the materials are comparable to those of well-characterised and widely utilized reference materials from the US Geological Survey and the Geological Survey of Japan. This is the first report of the Sr and Nd isotopic composition of standards GBW07111, GBW07112, GBW07121, GBW07122, GBW07123, GBW07124 and GBW07125. Our results are useful for quality control and assurance between laboratories and provide a robust reference-rock dataset for future studies involving classical Sr and Nd isotopic geochemistry.

Genesis of salt deposits in the Jiangling Sag, Jianghan Basin, China: Constraints from H, O, and C isotopes and fluid inclusions of evaporites

Due to Yanshan movement and Himalayan movement, a series of faulted basins were formed in the late Cretaceous and Paleogene, including Shashi Formation of Paleocene in Jiangling sag of Jianghan Basin, when a set of salt lake was deposited. Analysis of lacustrine carbonate rocks in Shashi Formation of Paleocene shows that the δ13CPDB values of carbonate rocks range from −4.8 ‰ to −1.0 ‰, with an average value of −3.3 ‰. The δ18OPDB values ranged from −5.4 ‰ to −0.6 ‰, with an average value of −3.2 ‰. The positive correlation between δ13CPDB and δ18OPDB of the Shashi Formation carbonate rocks indicates that they developed in a relatively closed brackish lake system with obvious evaporation. The homogenization temperature of the upper Shashi Formation in Jiangling sag ranges from 15.3 °C to 51.8 °C, mainly concentrated in 25–30 °C. The δ18O isotope of halite inclusions ranges from −0.8‰ to 9.4‰, with an average of 4.9‰. The δD isotope of halite inclusions ranges from −91.3‰ to −65.0‰ with an average of −79.3‰, which are all lower than the Global Meteoric Water Line. The intense evaporation environment is consistent with the overall drought paleoclimate at that time. The quantitative LA-ICP-MS was used to analyze the composition of the primary inclusion of halite, and it was concluded that the original brine composition was Na-K-Mg-Cl-SO4 system with relative low concentration of Ca2+, high concentration of Mg and SO42- ions and K ions. The high content of Li, B, Br and Rb is related to the intense volcanic activity, deep fluid source and hot spring recharge in Jiangling Depression at that time. Based on carbonate carbon and oxygen isotopes, fluid inclusions temperature and composition, it is concluded that during the Shashi Formation period of Paleocene in Jiangling Sag, the lake basin was well sealed, with high salinity and high temperature, and belonged to a salt lake sedimentary environment, which was favorable for the deposit of salt deposits.

Strontium isotope proxy of sedimentological records reveals uplift and erosion in the Southeastern Neo-Tethys ocean during the late Cretaceous

The mutual interplays between plate tectonic processes, orogenesis and continental uplift, high-flux magmatism, and high sedimentation rates can affect the geochemical signatures and composition of marine sediments. Here, we examine two major disconformities, the Cenomanian–Turonian boundary (CT-ES) and the middle Turonian (mT-ES) exposure surfaces, from the Upper Cretaceous sedimentary successions of the southeastern Neo-Tethys Ocean in the Zagros Basin (Iran). The disconformities are expressed as distinct positive peaks in rubidium (Rb) contents and 87Sr/86Sr isotopic ratios of carbonates. The 87Sr/86Sr values of samples bracketing the disconformities in seven well cores give average age ranges of 94.4–93.6 Ma for the CT-ES and 91–86 Ma for the mT-ES. These ages fall in the timespan of forearc/ophiolite formation through subduction initiation in the Neo-Tethys realm (southern margin of Eurasia), high convergence velocities between Arabia and Eurasia, and blueschist exhumation. All these processes involved buckling of the Neo-Tethyan lithosphere, initiating the Neo-Tethys closure and a high erosion rate on the Eurasian margin. The first two mechanisms exerted considerable compressional forces on the adjacent carbonate platforms, reactivated basement faults, and led to the uplift and erosion of the Arabian Plate, which provided the high contents of Rb and the high 87Sr/86Sr ratios in the carbonates.

Strontium isotope dating influenced by Rubidium contamination from terrestrial material: A case study from the Cenozoic dolomite in the Xisha Islands, South China Sea

AbstractStrontium isotopes (87Sr/86Sr) are commonly used to assess the age of Cenozoic dolostones found on many isolated oceanic islands. The possible influence of Rubidium (Rb) content on the 87Sr/86Sr ratios, however, has generally been ignored. This critical issue is assessed by examining the 87Sr/86Sr ratios and elements (Rb, Sr, Al, Ti and K) of seventy‐one samples that came from a ca 339 m thick cored interval of Cenozoic dolomite on the Xisha Islands, South China Sea. For the dolomite from the upper Pliocene Yinggehai Formation (180.5 to 308.5 m; average 23% dolomite) there is a positive correlation between the 87Sr/86Sr ratios and Rb concentrations, whereas for the dolomite from the lower late Miocene Huangliu Formation (308.5 to 519 m; average &gt;98% dolomite) such a correlation is not evident. Combined with high‐temperature experiments, correlation between Al, Ti, K, Rb and 87Sr/86Sr indicates that Rb containing old 87Rb from terrestrial materials modified the 87Sr/86Sr ratios of the Yinggehai dolomite, but not those from the Huangliu dolomite. This is mainly attributed to the different sources of terrestrial dust carried by different East Asian monsoon systems between the late Miocene and Pliocene, and probably also influenced by the dolomitization process to some extent. To test for 87Rb contamination, extrapolation of results from the Yinggehai dolomite and Huangliu dolomite indicate that concentrations of Rb &lt; 1 ppm, Al &lt; 1000 ppm, Ti &lt; 15 ppm and K &lt; 250 ppm in the dolomite indicates that terrestrial inputs are minimal and that the measured 87Sr/86Sr ratios can be used for determining the dolomitization age. Potentially, these concentration thresholds may serve as a screening criterion for assessing the reliability of Sr isotope chronostratigraphy of other island dolostones throughout the world.

Petrogenesis of the granitoids related to skarn-type mineralization in the Nyainqentanglha Metallogenic Belt, Tibet

The Nyainqentanglha Metallogenic Belt (NMB) is an economically important lead-zinc ore province located in the Central and Southern Lhasa subterrane, Tibet. The NMB consists mainly of skarn-type lead-zinc polymetallic deposits that form at the contact between Late Cretaceous-Eocene intrusive rocks and carbonatite/volcanic-sedimentary strata. These deposits are generally considered to be related to S-type granites formed by the Indo-Asian continental collision. However, the εHf(t) (ave. −1.6) of zircons from the mineralization-related granitoids indicates that it is crust-mantle mixing products. In addition, the volcanic rocks of the Dianzhong Formation, which have a close spatio-temporal relationship with the skarn-type deposits, typically show mantle-derived features. Therefore, the occurrence of AFC processes in mantle-derived material passing through the thick basement of the Lhasa Terrane may better explain the genesis of the mineralization-related granitoids. In this study, we present results on zircon U–Pb ages, major and trace elements of the granitoids associated with skarn-type mineralization from the Narusongduo district. LA-ICP-MS zircon U–Pb dating shows that the granite formed in the Paleocene (58.6 ± 0.5 Ma). Combined with published regional data, we propose the mineralization age of the skarn-type deposits in the NMB ranges from the Late Cretaceous to Eocene. Detailed petrology and geochemistry of mineralization-related granitoids are evaluated to constrain the magmatic evolution process. The granitoids have high contents of SiO2 (mean 72.8 %), K2O (mean 4.0 %), Rb (mean 186.9 ppm), DI (differentiation index) 84.7, A/CNK (mean 1.3), and low contents of MgO, TFe, suggesting that the granitoids have undergone strong differentiation. In addition, the continuous decrease of P2O5 with progressive differentiation and the lower average P2O5 abundance suggest that the mineralization-related granitoids belong to the I-type granite. The results suggest that the mineralization-related granitoids in the NMB originated from the mantle and is the fractionated I-type granite formed by the process of AFC (Assimilation and Fractional Crystallization). Considering that Pb and Zn often coexist in deposits, we suggest that magmatic differentiation may play an important role in the formation of the granite-related Pb and Zn mineralization.

Fluid-rock interactions recorded by bulk-rock and mica compositions in the Xiuwacu granite-related quartz-vein W–Mo deposit, western Yunnan Province, China

The Xiuwacu deposit is a typical granite-related quartz-scheelite-molybdenite vein type deposit hosted within sandstones and sandy slates in the southern Yidun Terrane, western Yunnan Province, China. The Xiuwacu complex comprises the Late Triassic biotite granite and Late Cretaceous monzogranite porphyry (MGP) and aplite granite. Extensive and intensive alteration including potassic, propylitic, phyllic, silicic and argillic alteration developed within the Late Cretaceous monzogranite porphyry. Greisenization and pegmatization occurred in the roof of the Xiuwacu complex, suggesting large-scale fluid-rock interactions. However, the effects of fluid-rock interactions on the elemental exchange and ore-forming processes at Xiuwacu still remained unclear. This study firstly reported whole-rock major and trace elements of representative altered rocks and in situ major and trace elements of micas from fresh and altered rocks, and quantitively constrained the mobilization of elements by normalized isocon diagrams. The altered MGP are characterized by higher loss on ignition (LOI) values (>2), lower light rare earth elements (LREEs) and variable large ion lithophile elements (LILEs) contents, with higher Cs, K, Rb and Ba contents and lower Sr content than fresh MGP. The classification diagram based on mica composition shows that magmatic biotites from the Late Triassic biotite granite and Late Cretaceous monzogranite porphyry belong to Fe biotites. Hydrothermal micas from pegmatoid and greisen belong to Li-phengites and zinnwaldites, and hydrothermal micas from quartz-molybdenite vein are classified as zinnwaldites. Li-phengites and zinnwaldites have relatively lower F contents, higher W, Sn, Li, Cs contents than biotites, intergrown with calcite and ankerite, suggesting CO2-rich, F-poor and rare metal-rich nature of hydrothermal fluids. Based on a compilation of fluid inclusions, H–O–S-Sr isotopes, scheelite geochemistry from previously published literatures and compositions of altered rocks and micas from this study, the tungsten ore-forming processes at Xiuwacu could be concluded as follows: (1) the initial moderately-oxidized, F-rich fluids exsolved from parental magmas of MGP form fluorite-quartz assemblages (pegmatoid; 400–300 °C); (2) the F-poor, W-rich, moderately acid fluids cause the breakdown of Ca-rich plagioclases, which consumes H+ and provides Ca2+ for the precipitation of early-stage scheelites (greisen; approximately 300 °C); the evolved nearly neutral and medium- to low-temperature fluids (300–150 °C) drive the fluid-rock interactions to supply Ca2+ for the deposition of main-stage scheelites. The deposition of Mo was not determined by the fluid-rock interactions, but by the ore-forming fluids transformed from oxidized to reduced nature.

Simultaneous deep eutectic solvent based microextraction for monitoring Brilliant blue and rhodamine B in foodstuff and industrial samples

Brilliant blue (Bb) (legal food dye) and rhodamine b (Rb) (illegal food dye) are artificial dyes used in different industries such as food and cosmetic. Due to their toxic effects on humans, extreme exposure to these food additives can lead to health problems. Simultaneous deep eutectic solvent based (DES) microextraction method was developed first time for spectrophotometric determination of Bb and Rb. DES composed of 1-heptanol and tetra butyl ammonium bromide (TBAB) was synthesized and then used for simultaneous microextraction of Bb and Rb. Effects of pH, composition ratio and volume of DES, time of vortex mixing, centrifugation time and rate, sample volume and matrix components were investigated to achieve quantitative simultaneous microextraction of the dyes. The detection limits 20 and 13 µg/L, linear dynamic ranges between 0.068–4.5 and 0.042–3 µg/mL and 40 preconcentration factors were obtained for Bb and Rb, respectively. Bb and Rb contents of commercially available industrial samples were determined between 3.85–6.28 µg/mL and 1.05–23.50 µg/g for liquid and solid samples, respectively. Quantitative recoveries ranging from 92 to 106% were obtained in multivariable analyte addition-recovery tests. In addition to dye content determination process of real samples and method development studies, extraction mechanisms of method were elucidated for Bb and Rb. Green Analytical Procedure Index (GAPI) and score of Analytical Eco-Scale (AES) were evaluated.

In situ analysis of mica from the Daguanshan granites in Western Yunnan: Implication for Sn enrichment and mineralization

The potential of tin mineralization associated with the Triassic Lincang granite batholith in Western Yunnan, China, has been poorly understood, despite the batholith being considered the northern extension of the Southeast Asian Tin Belt. To address this issue and gain insights into the mechanism of tin enrichment, we investigate the major and trace element compositions of biotite and muscovite from four granite units in Daguanshan, including hornblende-biotite granite, biotite granite, two-mica granite, and muscovite granite in the Hongmaoling Sn deposit. From the hornblende-biotite granite to two-mica granite, the biotite composition varies from Mg-biotite to Fe-biotite with increasing MnO and decreasing K/Rb. The Fe3+-Fe2+-Mg2+ diagram and decreasing Mg/(Fe + Mg) ratios of the biotite indicate reducing conditions. From two-mica granite to muscovite granite, the muscovite Li, F, Rb and Cs concentrations generally increase with decreasing K/Rb, suggesting a magmatic fractionation trend. The variations in zoned muscovite composition reflect a high degree of magmatic fractionation and a lack of fluid interaction. Biotite tin concentrations increase from ∼ 18 ppm in the hornblende-biotite granite to ∼ 36 ppm in the biotite granite and further to ∼ 62 ppm in the two-mica granite. In addition, tin concentrations increase from ∼ 180 ppm in the core to ∼ 330 ppm in the rim of muscovite in the muscovite granite. These data indicate that magmatic fractionation is critical to Sn enrichment in the Hongmaoling deposit. The Nb/Ta ratio and tin concentration in mica from tin mineralized granites are generally higher than those from barren granites, indicating they could be used as reliable indicators for assessing tin metallogenic potential.

Age, clinopyroxene geochemistry and petrogenesis of post-collisional magmatic rocks in the Jonob-e-Sechangi area, Lut block, eastern Iran

The Lut-Sistan region, eastern Iran has an extensive record of Eocene-Oligocene magmatism the origin of which is not fully understood. In this study, we analyze a set of volcanic rocks in the Jonob-e-Sechangi area of the Lut block. U-Pb zircon analyses demonstrate that magmatism can be divided into two age groups. Group 1 formed at ∼45 Ma and involved different felsic (calc-alkaline rhyolitic to dacitic) and intermediate (high-K calc-alkaline andesitic) rocks. All samples from Group 1 display nearly identical initial 87Sr/86Sr values (87Sr/86Sri = 0.7045-0.7056). However, the felsic rocks show higher ԐNdt (+2.21 to +2.73) and lower TDM (0.51-0.61 Ga). In contrast, intermediate rocks have ԐNdt values of +1.27 to +2.23 and TDM values between 0.63 and 0.74 Ga. Additional geochemical variations suggest that the felsic and intermediate rocks of Group 1 are not co-genetic. The felsic extrusive rocks in the Jonob-e-Sechangi area likely formed from the partial melting of the amphibolitic arc crust. In contrast, the high-K calc-alkaline andesitic rocks of Group 1 may have originated from low-degree partial melting of a spinel-peridotite mantle source.Group 2 formed basaltic andesite to andesitic rocks at37-40 Ma, showing high-K calc-alkaline to shoshonitic compositions, relatively high 87Sr/86Sri (0.7047- 0.7076) and relatively low ԐNdt (0.48 to-5.86). These geochemical features require magma derivation from a mantle source that is not only elementally but also isotopically enriched, followed by variable fractionation and crustal contamination. The enriched mantle source was most likely resided in the lithosphere and formed by metasomatism by continental crust-derived materials. Clinopyroxene trace elements compositions display marked variations between different magmatic rocks. Clinopyroxene in dacitic samples of Group 1 shows relatively high contents of Sr, Rb, and Ba whereas that in Group 2 rocks has relatively high contents of Sc, V, Ga, Nb, Zr, Hf, Y and rare earth elements (REE). The findings of this study show that the intricate interactions between the lithosphere and asthenosphere, stemming from post-collisional delamination processes following the closure of the Sistan Ocean and the collision of the Lut-Afghan blocks, led to differing levels of partial melting in the region's heterogeneous metasomatized mantle. This phenomenon explains the diverse range of volcanic rocks found not just in the Jonob-e-Sechangi area but also in other regions of the Lut Block.

Whole-Rock Geochemistry and Mica Compositions in Lijiagou Pegmatite Spodumene Deposit, Western Sichuan, China

The Lijiagou pegmatite spodumene deposit, located in the middle of the Songpan–Garze Fold Belt and southeast of the Ke’eryin ore field, is a newly discovered super-large deposit. In order to reveal the metallogenic tectonic environment and evolution process of pegmatite, based on the study of the geological characteristics of pegmatite, we carried out a whole-rock geochemical analysis of Ke’eryin two-mica granite and Lijiagou pegmatite and carried out a detailed electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis of mica minerals in each zonal pegmatite. The results show that the Ke’eryin two-mica granite is mainly formed in the transition period from syn-collision to post-collision. After the end of the continental collision, the crust is squeezed and thickened in the post-collision extensional transition tectonic environment. Mica from the microcline pegmatite zone (MP) to the albite spodumene pegmatite zone (ASP) in pegmatite show different compositions and structural characteristics, with the evolution trend in the direction from muscovite to Li-bearing mica. The type of mica from MP to AP is mainly muscovite, and Li-bearing mica appears in ASP, which is secondary and metasomatic at the edge of primary muscovite. From MP to ASP, there was a negative correlation between Nb/Ta, K/Rb and the Li, Rb, and Cs contents of mica, while the contents of Li, Rb, Cs, and F in the Li-bearing mica of ASP increased sharply. This evidence illustrates that the favorable tectonic environment contributed to the formation of the Lijiagou pegmatitic spodumene deposit. Lijiagou pegmatite experienced the magmatic–hydrothermal evolution process and has a high degree of differentiation and evolution from MP to ASP, which gradually increased. Combined with the change in mica type, it is considered that ASP formed from the stage of magmatic transition to hydrothermal and was a hydrothermal environment, and Li, Rb, and Cs mainly began to enrich at the stage of magmatic–hydrothermal transition.

Unraveling the sources of major, trace and rare earth elements in the waters of a high latitude proglacial environment: Weathering vs. atmospheric signature in Northern Patagonia

Glaciers are important water reservoirs and are extremely sensitive to the effects of climate change. The Manso River basin, in Northwest Patagonia, Argentina, is a typical hydrological system with actively retreating glaciers. In this article, the proglacial environment was examined to assess the sources and the geochemical processes responsible for the chemical signatures of the following water subsystems: 1) clean glacial meltwaters (supraglacial influence, fed by “clean ice” glaciers); 2) dirty glacial meltwaters (subglacial influence, fed by “dirty ice” debris-covered glacier); and 3) proglacial runoff (river). Results indicated that clean glacial meltwaters present high dissolved immobile and nonmobile trace elements, derived from atmospheric input with an anthropogenic component in Pb, Cu, V, and Ni. Dissolved concentrations of Sr, Mn, Rb, and major ions are the result of carbonation and hydrolysis processes. The dirty glacial meltwater presents the highest dissolved load due to the highest water-rock interaction. The proglacial runoff presents intermediate physicochemical characteristics. At the site where the clean and dirty glacial meltwaters mix, the cation denudation rate is 2075 meq+ m−2 y−1. Downstream, geochemical inverse modeling indicates that the Manso Superior River system produces, by weathering reactions, a rate of dissolved load of 2.67 108 mol year−1, along with a CO2 sequestration of 2.05 108 mol year−1, denoting that proglacial environments are an important scenario in the CO2 cycle. The results of this work provide a baseline for future studies in proglacial environments and highlight the importance of assessing metal concentrations and mobilization within the Andean cryosphere.

Comparison of the major- and trace-element compositions of the Kang-dian and Rössing-Husaib uraniferous leucocratic rocks

The Rössing-Husaib area is well-known for its low-grade and large-reserve U deposits hosted by leucogranites. The leucocratic dykes in the Kang-dian area of China resemble the Rössing-Husaib uraniferous leucogranites in occurrences and mineral assemblages, however, it remains disputable if the Rössing-Husaib and Kang-dian leucocratic rocks have consistent U-mineralizing processes. A comparison of the major and trace element data of the leucocratic rocks from both areas may help to better understand the ore-forming mechanisms and provide implications for exploration in the Kang-dian area. The positive correlation between Rb and P2O5 contents for the Rössing leucogranite samples is typical of S-type granitoids in spite of the low A/CNK ratios (∼1.0). The Rössing-Husaib uraniferous leucogranites are generally rich in K2O and Rb, and have high Rb/Sr and Rb/Ba ratios. In contrast, the Kang-dian leucocratic dykes have lower K2O and Rb contents, and lower Rb/Sr and Rb/Ba ratios, suggesting a clay-poor source. The U contents of the Rössing-Husaib and Kang-dian dyke samples are positively correlated with TiO2 contents, but show no correlation with Rb/Sr ratios, which is inconsistent with fractional crystallization. Low-degree partial melting of a U-rich protolith may account for primary U enrichment in the leucocratic rocks. The variable major- and trace-element compositions of the Kang-dian dyke samples may reflect wall-rock assimilation and/or alteration to varying degrees, which further enhanced U enrichment. Relatively low Th/U ratios (∼0.1) favored the final crystallization of uraninite. The uraniferous leucogranites in the Kang-dian and Rössing-Husaib areas are commonly undeformed and emplaced along regional large faults and/or domes at the late stage of orogeny. We propose that decompression and uplift of basement rocks facilitated the generation of uraniferous melts, and regional large faults provided a pathway for the ascent of leucocratic magma from depth.