Major Trace Elements Research Articles

Role of NMP22 and major trace element in diagnosis of bladder cancer

Role of NMP22 and major trace element in diagnosis of bladder cancer

Chemical Composition of Quasi-ultrafine Particles and their Sources in Elderly Residences of São Paulo Megacity

Atmospheric quasi-ultrafine particles (qUFP; PM<0.25) can cause harmful effects to human health, mainly to elderly people. Although not always considered, these effects can be mostly due to its chemical composition. The scope of this work is (i) to quantify the abundance of ions and trace elements in qUFP in elderly residences, (ii) to identify the sources of these qUFP and (iii) to estimate the respiratory deposition doses (RDD) of qUFP and black carbon (rBC), which is an important component of qUFP, to various parts of the respiratory tract. In order to evaluate the qUFP chemical composition in elderly residences in the Metropolitan Area of Sao Paulo (MASP), we collected qUFP by using a Personal Cascade Impactor Sampler (PCIS). We analysed ions by chromatography and trace elements by Energy Dispersive X-Ray Fluorescence. We identified the sources of qUFP by applying Positive Matrix Factorization. We calculated the RDD through an equation, which use the tidal volume of lung, the typical breath frequency, the deposition fraction and the mass concentration of different size fractions of a PM. We collected 60 samples from 59 residences between May 2014 and July 2015. The major of ions concentrations in qUFP were found to be SO42- and NH4+, and the major trace elements were Si and Fe. Some residences have a high concentration of the toxic heavy metals Cu, Ni, Pb and Cr. We found six dominant sources of the indoor qUFP: vehicular emission (57%), secondary inorganic aerosol (21%), soil and construction (7%), wall painting (7%), cooking (5%) and industry (3%). The maximum RDD of qUFP and rBC are in the tracheobronchial part. Our results show that vehicular emissions dominate the indoor qUFP concentrations and uptake in elderly residences in the MASP.

Tectonic Settings and Petrogenesis of Pan-African S-Type Granitoids in Anka Schist Belt, NW, Nigeria

Research into geotectonic settings of the Anka schist belt was regionally carried out by (Holt, 1982) stating that there is no evidence of significant partial melting or metasomatism. This research uses chemical data of some Pan-African granitoids within the Anka schist belt to explain the tectonic setting and petrogenesis of the S-type granitoids intruding the metasediments within the Anka schist belt. Twenty-five (25) representative samples of granitoids was analyzed for major oxides and trace elements composition. Results obtained from the chemical data was used to plot various classification diagrams. The granitoids in the study area plots within the orogenic class and the use of trace element discrimination diagrams as a means of fingerprinting the tectonic environments revealed that the granitoids ranges from syn-collision to late orogenic field. The granitoids which plotted in the syn-collision field is a characteristic of chemical affinity of syn-collision peraluminous granites with highly fractionated volcanic-arc magmas. The petrogenesis of the S-type granitoids in the study area are greywacke sourced which is largely metagreywacke and metapelitic sourced during partial melting. Keywords: Granitoids, Pan-African, S-type, Metasediments, Partial melting DOI : 10.7176/JNSR/10-2-08 Publication date: January 31 st 2020

Sarıhıdır manganese mineralization related to travertine, Central Anatolian Volcanic Province, Turkey

ABSTRACT Sarıhıdır travertines and associated manganese mineralization are located in an area known as the Central Anatolian Volcanic Province (CAVP). The topic of the study, the Sarıhıdır manganese mineralization, was deposited in association with fault zones in this tectonically-active region. Paragenesis of the mineralization includes pyrolusite, rhodochrosite and goethite with gangue minerals of calcite and quartz observed. Diagrams drawn using major oxide and trace elements like Fe–Mn–(Ni+Co+Cu)×10, Fe-Si×2-Mn, Co/Ni vs Cu+Co+Ni, Si/Al, Na/Mg, Fe/Ti vs. Al/(Al+Fe+Mn), Co+Ni/As+Cu+Mo+Pb+V+ Zn and FeO–MnO2–10× MgO show the mineralization found in the region is sourced in the hydrothermal field. The low total REE values and LREE>HREE ratio indicate the effect of hydrothermal solutions. Additionally, Ce, Eu and Ceanom anomalies indicate the source of the mineralization was hydrothermal with oxic-anoxic formation environment. The Y/Ho ratio is mean 30.1 which is lower compared to hydrothermal fluids. Mean values are δ13CPDB 12.24‰ and δ18OPDB 10.87‰ indicating deposition from fluids with a deep CO2 component. In conclusion, the Sarıhıdır mineralization and travertine were determined to have formed about 50–53 ka (Upper Pleistocene) based on U-series age data, as fault-controlled, hydrothermal-sourced mineralization.

The role of accreted continental crust in the formation of granites within the Alpine style continental collision zone: Geochemical and geochronological constrains from leucogranites in the Çataldağ Metamorphic Core Complex (NW Turkey)

The recently discovered Çataldağ Metamorphic Core Complex (ÇMCC) of Eo-Oligocene age is situated in NW Turkey, which is a part of the Alpine collisional belt. The footwall of the ÇMCC consists of a granite-gneiss-migmatite complex (GGMC) with a domal structure. Here, we document new major-trace element geochemistry, Sr-Nd-Pb isotope characteristics and Ti-in-zircon thermometry data from granites and syn-plutonic mafic dykes that are connected to the gneiss-migmatite dome of ÇMCC, and discuss granitic melt evolution within the context of the syn-to post-collisional evolution of the western Anatolian orogenic crust. Granites of the GGMC include both peraluminous garnet-bearing leucogranite and two-mica granite that emplaced from 32 to 35 Ma. Both types of leucogranite are enriched in light rare earth elements (Rb, U, K, Pb) and depleted in HFSE (Nb, Ta, Zr, Ti). Their 87Sr/86Sr, 206Pb/204Pb and 207Pb/204Pb initial isotope values range from 0.7094 to 0.7113, 18.79 to 18.91, and 15.71 to 15.73, respectively, and εNd(33) values vary between −5.13 and − 7.79. On the other hand, mafic dykes show similar isotopic characteristics (87Sr/86Sr(33) = 0.7055, εNd(33) = −1.8 and 206Pb/204Pb = 18.8) to enriched mantle melts. Geochemical modelling shows that the granites have dominant crustal melt component (85–70%) and a minor mantle component (<30%). According to partial melting modelling and Ti-in-zircon thermometer calculations, granitic melt was formed by water-absent muscovite dehydration melting of a micaschist source (a melt fraction of max. 35%) at ≥7–10 kb and 739–840 °C. Whole rock geochemistry, isotopic characteristics and inherited zircon chronology, combined with the geology of the region, indicate that granitic melts were derived by partial melting of Anatolide-Tauride crustal units that were underthrusted below the Sakarya Continent along the İzmir-Ankara Suture Zone. On the other hand, the source of the syn plutonic mafic dykes emplaced in the core of the ÇMCC is inferred to derived from enriched mantle (EM II) that lay beneath the western Anatolian orogenic crust. We infer that partial melting and melt migration to produce leucogranites are most probably related to thermal weakening and partial removal of western Anatolian young orogenic lithosphere during the transitional phase between the latest phase of collision and the earliest phase of extension, in the Eo-Oligocene.

PIXE Investigation of Ancient Linen Fabrics Dated from Old Kingdom to Ptolemaic Ages (2200-300 B.C.)

External milli-beam particle induced X-ray emission spectroscopy (PIXE) has been used as non-destructive technique to investigate ancient linen fabrics from pre-dynastic and Ptolemaic ages belonging to the archaeological collections of the Egyptian Museum of Turin and to the Civic Archaeological Museum of Bologna, Italy. 9 linen fabric samples dated from Old Kingdom to Ptolemaic ages (2200-300 B.C.) were investigated, as well as 5 modern linen fabric samples, added for comparison. The primary goal of this work has been to advance the correct material description of the fabrics providing scientific data for further and more comprehensive comparative analyses. PIXE has provided quantitative analyses for the major (Si, Cl, K, Ca and Fe) and minor or trace elements as P, Ti and Mn, supplying information on the near-surface elemental composition. The achieved results contribute to comprehend the structural basis for the chemical properties of the considered materials, as well as to set up a classification according to the chemical composition, allowing in general a better understanding of the studied linen cloths.

Comparative geochemical study of the cherty rocks of the Taukha terrane (Sikhote-Alin) and its paleogeodynamic significance

The article presents the results of a comparative geochemical study of cherts and siliceous–clayey rocks composing the tectono-sedimentary complexes of various structural levels of the Taukha terrain of the Sikhote-Alin Late Jurassic–Early Cretaceous accretionary prism. The data obtained show that the same-aged parts of the cross-sections of the cherty–terrigenous sequences of the terrane lower and middle structural levels are characterized by significantly different contents and distribution patterns of major petrogenic oxides, trace, and rare-earth elements due to their accumulation in various facies of oceanic zones. The set of geochemical data indicates that the formation of both tectono-sedimentary complexes was carried out differently, gradually replacing each others’ facies oceanic zones, and started in the near-spreading ridge area, then in the pelagial, and completed in the continental-margin deposition environment. Based on the time interval of the facies conditions changing for each complex (i.e., time of transition from one facies zone to another), the speeds of a paleo-oceanic plate motion (and, correspondingly, the speeds of spreading) for individual intervals of the Jurassic were calculated. Differences in the spreading speeds at various sites of a paleorift zone caused the turning of a paleocontinent margin contour and spreading ridge axis at the perpendicular position, which in turn caused change of the geodynamic mode on the eastern margin of the Paleo-Asian continent at the Jurassic–Cretaceous transition.

Geochemical evidence for the production of granitoids through reworking of the juvenile mafic arc crust in the Gangdese orogen, southern Tibet

Abstract Although continental crust is characterized by the widespread occurrence of granitoids, the causal relationship between continental crust growth and granitic magmatism still remains enigmatic. While fractional crystallization of basaltic magmas (with or without crustal contamination) and partial melting of mafic lower crust are two feasible mechanisms for the production of granitoids in continental arc regions, the problem has been encountered in discriminating between the two mechanisms by whole-rock geochemistry. This can be resolved by an integrated study of zircon U-Pb ages and Hf-O isotopes together with whole-rock major-trace elements and Sr-Nd-Pb isotopes, which is illustrated for Mesozoic granitoids from the Gangdese orogen in southern Tibet. The results provide geochemical evidence for prompt reworking of the juvenile mafic arc crust in the newly accreted continental margin. The target granitoids exhibit high contents of SiO2 (65.76–70.75 wt%) and Na2O + K2O (6.38–8.15 wt%) but low contents of MgO (0.19–0.98 wt%), Fe2O3 (0.88–3.13 wt%), CaO (2.00–3.82 wt%), Ni (&amp;lt;5.8 ppm), and Cr (≤10 ppm). They are enriched in large ion lithophile elements, Pb, and light rare earth elements but depleted in high field strength elements. The granitoids are relatively depleted in whole-rock Sr-Nd isotope compositions with low (87Sr/86Sr)i ratios of 0.7043–0.7048 and positive εNd(t) values of 0.5–2.6, and have relatively low 207Pb/204Pb and 208Pb/204Pb ratios at given 206Pb/204Pb ratios. Laser ablation–inductively coupled plasma–mass spectrometry and secondary ion mass spectrometry U-Pb dating on synmagmatic zircons yield ages of 77 ± 2–81 ± 1 Ma in the Late Cretaceous for their emplacement. Relict zircons have two groups of U-Pb ages in the late Mesozoic and the late Paleozoic, respectively. The whole-rock Sr-Nd isotopes in the granitoids are quite similar to those of Late Cretaceous mafic rocks in the Gangdese batholith. In addition, both synmagmatic zircons and relict zircons with Late Cretaceous U-Pb ages exhibit almost the same Hf-O isotope compositions to those of the slightly earlier mafic rocks. All these observations indicate that the granitoids were mainly derived from partial melting of the juvenile mafic arc crust. Therefore, reworking of the juvenile mafic arc crust is the mechanism for the origin of isotopically depleted granitoids in southern Tibet. It is this process that leads to differentiation of the juvenile mafic arc crust toward the felsic lithology in the continental arc. In this regard, the granitoids with depleted radiogenic isotope compositions do not necessarily contribute to the crustal growth at convergent plate boundaries.

Origin and fate of hydrothermal fluids at Piton des Neiges volcano (Réunion Island): A geochemical and isotopic (O, H, C, Sr, Li, Cl) study of thermal springs

As many ocean basaltic volcanoes worldwide, Piton des Neiges (Réunion Island) hosts a hydrothermal system that represents a potential geothermal resource. Despite several prospection campaigns over the past decades, this potential has never been confirmed because many aspects of fluid supply and circulation remain unclear. To track the origin and fate of hydrothermal fluids, we analyzed the geochemistry of thermal springs (water and gas), by combining conventional tracers (major-trace elements and O, H, C, Sr, Li isotopes) with Cl isotopes, a geochemical tool under development. Added to literature data, our new results allow us to compare the composition of thermal springs with cold waters, rocks, gas, and fumarolic deposits from La Réunion and elsewhere, and to untwine the complex history of fluid mixing that constitutes the geothermal system of Piton des Neiges.δ18OH2O and δDH2O values of springs (-8.67 to -4.9 and -56.3 to -23.5 ‰ VSMOW, respectively) are positioned close to the local meteoric water line, showing that thermal waters are of meteoric origin. However, their depletion in heavy isotopes relative to cold waters suggests a recharge strongly influenced by cyclones, with a possible contribution from high altitude (≥ 2000 m) rainfalls. Their absence of 18O enrichment relative to the local meteoric water line indicates that the isotopic exchange between rocks and water is very limited, and therefore suggests that their deep temperatures are relatively low and/or the water/rock ratios are high. δ13C values in thermal waters (-8.0 to +3.2 ‰ PDB) and gases (-6.7 to -5.3 ‰ PDB) confirm that carbon is essentially of magmatic origin, which we interpret as supplied by regional degassing of La Réunion hotspot. Major-trace elements and 87Sr/86Sr (0.704142 to 0.704336), δ7Li (+2 ‰ and +34.8 ‰ LSVEC), and δ37Cl (-0.35 ‰ and +0.40 ‰ SMOC) compositions show that three additional processes contribute to the mineralization of thermal waters: 1) interaction with basalt at temperatures ≥50 °C, 2) very limited seawater contamination (< 3 mol%), and/or 3) leaching of trachyte or scrubbing of fumarolic gas or condensates emitted by a shallow trachytic magma in the volcanic edifice.The geothermal system of Piton des Neiges is thus the result of meteoric water interaction with a trachytic heat source (as a solidified intrusion or a magma pocket), unrelated to the CO2 flux. We also emphasize that thermal waters at Piton des Neiges are exceptionally isolated from seawater compared to other geothermal systems in ocean island volcanoes worldwide, which implies a heat source located above the seawater/freshwater interface. These inferences are of critical importance for the future geothermal exploration on the island, as they suggest that the geothermal resource is within reach of relatively shallow drilling depths (≤1000 m).

Geochemical evidence for reworking of the juvenile crust in the Neoarchean for felsic magmatism in the Yunzhongshan area, the North China Craton

The North China Craton experienced two phases of tectonothermal events at ca. 2.8–2.7 Ga and ca. 2.6–2.5 Ga, respectively. Although 2.6–2.5 Ga granitic gneisses and metavolcano-sedimentary sequences are widespread in the craton, the major stage of crustal growth has been determined to occur at 2.8–2.7 Ga in terms of whole-rock Sm-Nd and zircon Lu-Hf isotope studies. It has been intriguing how the vast 2.8–2.7 Ga juvenile mafic crust would have differentiated into the 2.6–2.5 Ga felsic crust. This issue is addressed in the present study by investigating zircon U-Pb ages and Lu-Hf isotopes as well as whole-rock major-trace elements and Sm-Nd isotopes in Neoarchean felsic igneous rocks from the Yunzhongshan area in the central part of the North China Craton. Zircon U-Pb dating of felsic volcanics, TTG gneisses and high-K granites yields three groups of crystallization ages at 2562–2508 Ma, 2537–2504 Ma and 2518–2508 Ma, respectively, consistent with ages for mafic volcanics in the target area. Zircon Lu-Hf and whole-rock Sm-Nd isotope data indicate that all these rocks were ultimately originated from the ca. 2.8–2.7 Ga juvenile mafic crust. The felsic volcanics are subdivided into low-Si and high-Si suites. The low-Si rocks have higher MgO and FeO contents and contain abundant 2.8–2.7 Ga relict zircons with an age peak of 2.72 Ga, and were produced by partial melting of ~2.72 Ga TTG at ~730 to 750 °C. The high-Si volcanics were derived from partial melting of mafic restites after extraction of the ~2.72 Ga TTG, with significant amounts of garnet and amphibole, but no or rare plagioclase as residual phases, corresponding to a melting pressure at ~15 kbar. The TTG gneisses were produced by partial melting of ~2.8 to 2.7 Ga garnet amphibolites at ~10 to 15 kbar with variable amounts of garnet, amphibole and plagioclase in the residue. The high-K granites were produced by partial melting of ~2.8 to 2.7 Ga medium-high K mafic rocks at pressures of <10 to 12 kbar with a considerable amount of plagioclase in the residue. The TTG rocks and high-Si volcanics require a subduction origin to account for their enrichment in LILE, so that they were mostly likely derived from partial melting of the older arc crust with moderate enrichment in LILE and LREE. By contrast, the ultimate sources of the high-K granites would be the ~2.8 to 2.7 Ga medium-high K basalts, which have lower Zr/Sm ratios than the TTG gneisses and felsic volcanics, and even lower than the bulk continental crust, but consistent with modern island arc basalts. It is possible that the 2.8–2.7 Ga magmatism was subduction-related, with a compositional change of the mafic arc crust from relatively sodic to more potassic at around 2.7 Ga. This may be caused by accretion of the ancient oceanic arc onto the ancient continental margin. It was followed by both growth of the juvenile crust and reworking of the older arc crust in the late Neoarchean. Such series of magmatic processes can account for the voluminous generation of the 2.56–2.50 Ga felsic and mafic igneous rocks in the central part of the North China Craton. Taken together, both growth and reworking of the juvenile crust were realized through accretionary and rifting orogeneses, marking the operation of plate tectonics in the Neoarchean.

Chemical Characteristics and Development Significance of Trace Elements in Produced Water with Coalbed Methane in Tiefa Basin.

Coalbed methane (CBM) is an unconventional natural gas resource. CBM mining releases a large amount of coproduced water, and the trace elements of CBM coproduced water can provide a basis for the exploration and development of CBM. The contents of eight major trace elements in the produced water from wellhead were tested and analyzed based on seven CBM wells in Tiefa Basin. The research indicates that Sr and Ba are the dominant trace elements with the highest concentrations in produced water. There is a positive correlation among Li, Sr, and Rb by cluster analysis and correlation analysis, which may be affected by the total dissolved solids and pH in the groundwater. The contents of Li, Sr, and Ba increase with the burial depth of coal seam and could be influenced by the fault. The gas production of CBM wells is affected by the depth of the coal seams, and there is no significant correlation between water production and the coal seam depth. However, faults have an important impact on gas and water production. The productivity of coalbed methane is affected by hydrogeological conditions and structure because the productivity of CBM wells located in different tectonic locations varies with the change of Li, Sr, and Ba contents.

Assessment of Groundwater Salinity in Aloha Pliocene Aquifer of Marbella (Málaga)

In order to study the origin of the salinity and the salinization mechanisms that operate in the Pliocene Aloha Aquifer, hydrochemical and isotopic environmental techniques have been used, due to their known effectiveness and usefulness in the identification of water-rock interaction processes, location of recharge zones and its origin. Analyzing major ions, trace elements, ionic ratios and isotopic ratios of the elements of the water molecule, stable isotopes (δ18O and δ2H) and δ18O and δ34S of sulphate. Previous hydrochemical studies of the Pliocene Aloha Aquifer indicate high concentrations of Cl- and Na+ as well as HCO3, SO4 and Ca that should be indicated the interaction with waters of highersalinity, but also with rocks (longer residence time in the aquifer). Therefore, as a starting hypothesis, two possible origins of the high salinity are considered: mixture with seawater or connate waters stored in Pliocene formations. Finally, the study confirmed that the salinity of the Aloha Aquifer is of a localcharacteristic and not due to seawater intrusion.

Mars Science Laboratory Alpha Particle X-ray spectrometer trace elements: Situational sensitivity to Co, Ni, Cu, Zn, Ga, Ge, and Br

Alongside major and minor elements, trace elements in Martian samples quantified through geochemical analyses by the Mars Science Laboratory (MSL, Curiosity) Alpha Particle X-ray Spectrometer (APXS) provide insight into ancient environments on Mars. APXS spectrum simulations facilitated the characterization of trace elements measured by the APXS under experimental situations commonly encountered on Mars. The precise quantification limits (PQL) obtained under ideal conditions are consistent with limits of detection in the literature and increase with degrading spectral quality. Major trace element species, such nickel, zinc, and bromine, with typical concentrations in the 100s of μg/g (or less), are quantifiable even with short (e.g., 20 min) early morning measurements between drives given the typical concentrations at the MSL site, Gale Crater. Target compositions currently in the public domain with major trace element species below the derived PQL specific to each measurement are noted. Quantification of copper, gallium, and germanium at 30 ppm and <10% uncertainty can be achieved with measurement durations of 6 h, 3 h, and 4 h respectively. In areas of local enrichment, such as the Murray formation, germanium abundance can be assessed with <10% uncertainty in 30 min. The detection and quantification of cobalt is hindered by the presence of overlapping peaks associated with the ubiquitous iron and nickel present in Mars samples. Only a single sample interrogated by Curiosity's APXS up to sol 2003 contains cobalt at detectable levels, coinciding with a composition similar to terrestrial ferromanganese crusts and nodules formed under inorganic aqueous conditions. The work presented herein emphasizes the need for acquiring quality APXS measurements where reliable trace element quantification is desired and offers guidance to improve the tactical operation of the MSL APXS instrument.

Major and trace element abundances in volcanic glass shards in visible tephras in SG93 and SG06 drillcore samples from Lake Suigetsu, central Japan, obtained using femtosecond LA–ICP–MS

AbstractThe major and trace element concentrations of volcanic glass shards from visible tephra layers in the SG93 and SG06 cores from Lake Suigetsu, central Japan, were determined by femtosecond laser ablation–inductively coupled plasma–mass spectrometry. The glass‐shard analyses, together with the petrographic properties of the tephra samples, allow the Suigetsu tephra layers to be broadly classified into tephras derived from calderas on Kyushu Island, and from Daisen and Sambe volcanoes in the Chugoku district of southwest Japan. The layers correlated with tephras from Kuju caldera and Daisen volcano, and with the younger Sambe tephras, have adakitic elemental features. A Suigetsu tephra sample correlated with the Sambe−Kisuki tephra based on petrographic properties has an elemental pattern similar to that of the Toya tephra from Hokkaido Island, northeast Japan. This match implies that tephras from northeast Japan, as well as Kyushu–Chugoku tephras, are possible correlatives of the Suigetsu tephra layers. Both petrographic properties and major–trace element data of volcanic glass shards are essential for robust tephra correlations, and hierarchical cluster analysis proved additionally useful in statistically evaluating relationships among the tephras.

Evolution of gas hydrates inventory and anaerobic oxidation of methane (AOM) after 40ka in the Taixinan Basin, South China Sea

Gas hydrates are the largest carbon sink on the earth and have an important impact on global climate and the environment. We studied theδ34S,δ13C, major trace elements and P –Fe dates at station 973-4 which acquired from the cold seep area of the Taixinan Basin. The results showed that during the Last Glacial Maximum (LGM), Younger Dryas (YD), and the Last Deglaciation, Gas hydrate inventory (GHI) was significantly reduced. And during the LGM, anaerobic oxidation of methane played an important role in preventing methane from leaking into seawater and the atmosphere. Because that there was no acidification of seawater or increase in PCO2. Meanwhile, rapid rate of sediment accumulation caused by isobaric flow provided accumulated material for Anaerobic Oxidation of Methan (AOM) during the LGM. The rapid rate of sediment accumulation also created a good environment for the formation of PCFA and vivianite below the sulfate methane transition zone (SMTZ). And according to changes of elements with depth, we conclude that the effect of methane anaerobic oxidation on redistribution of elemental P–Fe is divided into three processes: SMTZ rapid movement (material accumulation); SMTZ gradually stable; and SMTZ fixation process. In this paper, the effects of sedimentary evolution and hydrate evolution on AOM are studied in detail, which is of great significance for further understanding of anaerobic oxidation of methane.

Up to 1% Pb isotope disequilibrium between minerals hosted in dacites from the Guagua Pichincha volcano, Ecuador: Implication for tracing the source and crustal history of continental arc magmas

Continental arc lavas display geochemical signatures that reflect both mantle metasomatism by slab fluids or melts and extensive differentiation of magmas within crustal reservoirs. The relative effect of source and crustal processes are difficult to disentangle based on whole-rock compositions. This issue is critical in Ecuador where volcanism occurs through a thick continental crust (>50 km). This study reconstructs the history of melts feeding the Guagua Pichincha volcano, Western Cordillera, by analysing the Pb isotope composition and major-trace element content of individual minerals (33 amphiboles, 4 orthopyroxenes and 18 plagioclases) hosted in two dacite samples. It uses a low-blank wet-chemistry method for precise analysis of Pb amounts as low as 150 pg.Early crystallized, high-Al amphiboles with Al2O3 ≥ 9.8 wt% and Eu/Eu* > 0.7 have the lowest and most heterogeneous 206Pb/204Pb (18.816–18.999), whereas plagioclases have the highest and most homogeneous 206Pb/204Pb (19.003–19.023). Low-Al amphiboles and orthopyroxenes display intermediate compositions and variability (18.934–19.007). The 206Pb/204Pb ratio correlates negatively with Eu/Eu* in amphiboles and orthopyroxenes, which indicates that the Guagua Pichincha magmas assimilate radiogenic Pb within the stability field of plagioclase (i.e. in the upper crust). The radiogenic ankaramites of the Guaranda unit, an accreted ocean terrain making the basement of the Western Cordillera, are the most suitable contaminant. If this is correct, the 206Pb/204Pb increase from the two most primitive amphiboles to their respective host rocks requires ca. 20% crustal assimilation, which is higher than previous estimates in the Northern Volcanic Zone but similar to those inferred for Central Andean mafic lavas. The two most primitive amphiboles with no significant Eu anomaly record the composition of melts before plagioclase crystallization. These deep melts have contrasted 206Pb/204Pb ratios (18.816–18.879) and contents of fluid mobile elements (Li, Cu, Rb, Pb) that probably reflect the input of different slab components to the mantle wedge. Melts in equilibrium with the two most primitive amphiboles of the Guagua Pichincha volcano are enriched in incompatible elements, but depleted in fluid mobile elements compared to the olivine-hosted melt inclusions of the older Rucu Pichincha volcano. This supports previous inferences based on whole-rock data that the mantle source of the Pichincha Volcanic Complex has changed through time.

Geochemistry characteristics and dolomitization mechanism of the Upper Cambrian dolomite, eastern Ordos Basin, China

There are widely developed carbonate formations in the lower Palaeozoic, Ordos Basin, China. However, previous studies have paid more attention to the Ordovician formations and largely ignored the Cambrian formations, which also have a larger sediment thickness. Recently, with the continuous discovery of dolomite gas fields in the Ordovician Majiagou formation, more investigations have begun to focus on the deeper dolomite in the Cambrian Sanshanzi Formation (Є3s). This study looks into the origin of the dolomite through a combination of petrology, major–trace elements, and stable isotope and rare earth element (REE) analysis of samples from five outcrops. The results show that the main dolomite types in the study area are dolarenite (Type 1), micrite‐fine crystalline dolomite (Type 2), and medium crystalline dolomite (Type 3). The δ13C values and δ18O values of each dolomite formation are close to those of seawater‐derived dolomite and have slightly higher Na2+ concentrations, suggesting that dolomite formation is closely related to the denser seawater. The REE compositions are characterized by enrichment for light REEs and depletion for heavy REEs, exhibiting an apparent negative Eu anomaly and a slight negative Ce anomaly, indicating that the dolomites of the Є3s may form in a weak‐reduction to the weak‐oxidation environment. The total REE (ΣREE) concentrations of Type 3 dolomites are lower than other types, suggesting that those dolomites may mean that the REEs are lost during the diagenesis. Type 1 dolomite has lower MgO and CaO values and a higher Mn2+ concentration than the other two types of dolomites, indicating that Type 1 dolomite suffered the action of atmospheric fresh water. Type 2 dolomite has lower Mg and Ca values than Type 3 dolomite, suggesting that Type 3 dolomite has a higher dolomitization degree. Further study into the combined palaeogeographical background confirms the dolomitization model of the study area: Type 1 and Type 2 dolomites may have been formed by penecontemporaneous or seepage–reflux dolomitization during early‐stage diagenesis. Subsequently, stratigraphic uplift lead to the Type 1 dolomite suffering the action of atmospheric fresh water, but there was no dorag dolomitization. Type 2 dolomite became the main dolomite type by seepage–reflux dolomitization in this period. Later, Type 2 dolomite was converted into Type 3 dolomite during progressive burial.

Role of mantle and lower continental crust in the genesis of Eocene post-collisional granitoids: Insights from the Topuk pluton (NW Turkey)

We present here new mineral chemistry and major trace element and Sr-Nd-Pb-O isotope data as well as detailed field and petrographic studies of the Topuk Pluton (TP; ca. 48 Ma) and its hypabyssal counterparts. We aim to constrain the granitic magma genesis and emplacement and magmatic processes within the framework of post-collisional evolution of NW Anatolia. The TP is a shallow level intrusion (1.5–2.1 kbar, 680–760 °C, and 4.5–6.3 km depth) which is characterized by a dominant granodiorite composition and presents holocrystalline porphyritic texture. The pluton includes mafic microgranular enclaves (MMEs) of diorite/quartz diorite composition. During its emplacement, the pluton developed radial and ring fractures around itself, and aplite, porphyry dykes, and stocks were emplaced coeval with the pluton along these ring and radial fractures. The TP shows metaluminous and calc-alkaline I-type characteristics. Normal-mid ocean ridge basalt-normalized trace element patterns show that the samples are enriched in large-ion lithophile elements and light rare earth elements but depleted in Nb, Ti, and Ta elements. Granodiorite, MMEs, and hypabyssal rocks present similar initial 87Sr/86Sr and 143Nd/144Nd isotopic values, which lie in the ranges 0.705860–0.706247 and 0.512455–0.512584, respectively. The 206Pb/204Pb, 207Pb/204Pb, 208Pb/206Pb, and 207Pb/206Pb ratios are 18.831–19.046, 15.673–15.748, 2.0621–2.0725, and 0.82816–0.83321 values, respectively, while the δ18O isotope values range from 9.6 to 10.7.These similar Sr-Nd-Pb-O isotopic features of MMEs and host granodiorites indicate a common igneous precursor as the magma source. We infer that the magma-forming TP originated from enriched mantle type II (EMII) with contribution from the lower crust. The results of numerical modelling indicate that this lower crustal input ranges from 5 to 20%. The Eocene melt generation was most probably caused by the upwelling asthenosphere due to the break-off of Neo-Tethys slab in NW Anatolia.

Process-related isotope variability in oceanic basalts revealed by high-precision Sr isotope ratios in olivine-hosted melt inclusions

Melting of the proto-Iceland Plume produced the intra-plate lavas of the Faroe Islands. The lava series of the Malinstíndur Formation contains picrite flows which have accumulated up to 50% olivine pheno- and antecrysts. Whole-rocks, minerals and olivine-hosted melt inclusions (MI) from this formation, in addition to other Faroe Island lavas, were analysed for their major-trace element and Sr isotope composition. In comparison to other lavas from the Faroe Islands, the depleted incompatible trace-element composition of the population of inclusions investigated here is equivalent to that of its host-lava, and thus minorly influenced by post-entrapment crystallisation (PEC). High-precision Sr isotope ratios of silicate melt inclusions in olivine, binned by their Fo contents (Fo93–78, in 1 mol% Fo bins), reveal large variations in 87Sr/86Sr within a single lava flow. Both the 87Sr/86Sr and their variability increase with decreasing Fo content, suggesting progressive incorporation of different components during magma evolution, that is, concurrent mixing and crystallisation. The total variation in Sr isotope ratios in the MI population covers about 60% of the variation recorded in the erupted lavas of the entire Faroe Island archipelago, but is slightly biased towards more radiogenic 87Sr/86Sr. The variation of Sr isotope ratios and incompatible trace element concentrations is best explained by mixing-in of melts with different trace element and isotope compositions. Clinopyroxene barometry indicates that mixing of melts likely occurred at pressures higher than 0.6 GPa, in sub-MOHO magma conduits and sills. Hence the chemical and isotopic variability of the melt inclusions is influenced by magmatic processes during melt evolution, which must therefore also influence how source heterogeneity is reflected in the composition of the erupted basalts.

Zircon U–Pb geochronology, major-trace elements and Sr–Nd isotope geochemistry of Mashhad granodiorites (NE Iran) and their mafic microgranular enclaves: evidence for magma mixing and mingling

ABSTRACT Mashhad granitoids and associated mafic microgranular enclaves (MMEs), in NE Iran record late early Mesozoic magmatism, was related to the Palaeo-Tethys closure and Iran-Eurasia collision. These represent ideal rocks to explore magmatic processes associated with Late Triassic closure of the Palaeo-Tethyan ocean and post-collisional magmatism. In this study, new geochronological data, whole-rock geochemistry, and Sr–Nd isotope data are presented for Mashhad granitoids and MMEs. LA–ICP–MS U–Pb dating of zircon yields crystallization ages of 205.0 ± 1.3 Ma for the MMEs, indicating their formation during the Late Triassic. This age is similar to the host granitoids. Our results including the major and trace elements discrimination diagrams, in combination with field and petrographic observations (such as ellipsoidal MMEs with feldspar megacrysts, disequilibrium textures of plagioclase), as well as mineral chemistry, suggest that MMEs formed by mixing of mafic and felsic magmas. The host granodiorite is a felsic, high K calc-alkaline I-type granitoid, with SiO2 = 67.5–69.4 wt%, high K2O (2.4–4.2 wt%), and low Mg# (42.5–50.5). Normalized abundances of LREEs and LILEs are enriched relative to HREEs and HFSEs (e.g. Nb, Ti). Negative values of whole-rock εNd(t) (−3 to −2.3) from granitoids indicate that the precursor magma was generated by partial melting of enriched lithospheric mantle with some contributions from old lower continental crust. In the MMEs, SiO2 (53.4–58.2 wt%) is lower and Ni (3.9–49.7 ppm), Cr (0.8–93.9 ppm), Mg# (42.81–62.84), and εNd(t) (−2.3 to +1.4) are higher than those in the host granodiorite, suggesting a greater contribution of mantle-derived mafic melts in the genesis of MMEs.