Search

Platinum-group element (PGE) + Re abundances and Os isotopic compositions were determined for metasomatized peridotite and cumulate pyroxenite xenoliths from Kharchinsky Volcano, Kamchatka. Two peridotites have moderately high PGE concentrations with 2.9–3.3 ppb Os and smoothly variable PGE patterns similar to abyssal peridotites and encompassing primitive and depleted mantle compositions. One of these has unradiogenic Os (187Os/188Os = 0.1148) at the lower limit of compositions observed in abyssal peridotite which results in a time of Re depletion (TRD) model age of ∼1.8 Ga. These contrasts Kharchinsky peridotites that are Pt-Ir enriched with sharply fractionated PGE patterns with Pt/Pd = 132–168 and Ir/Ru ∼ 4.0. This pattern of enrichment in the heavier and more highly siderophile Pt and Ir over the lighter and more siderophile-chalcophile Ru and Pd ( Fleet and Stone, 1991 , Fleet et al., 1991 ) is consistent with sulfur depletion under oxidizing metasomatic conditions that leave a residue with PGE host minerals that are dominantly alloys. A single Ru-enriched peridotite with low PGE abundances is interpreted to reflect advanced stages of paragenesis driven by metasomatism and resulting in the loss of all PGE and Re relative to Ru. All Kharchinsky peridotites included in this study have relatively unradiogenic Os (187Os/188Os = 0.1148–0.1314) but some are coupled to PGE and lithophile element characteristics that require oxidizing metasomatic conditions (Ce/Ce*≪1.0) and desulfurization leading to a general loss of PGE and data patterns that are consistent overall with low abundances of relatively radiogenic Os in arc peridotites globally ( Brandon et al., 1996 , Widom et al., 2003 , Saha et al., 2005 ). Kharchinsky pyroxenites, which are relatively undeformed and only weakly metasomatized, have similarly fractionated PGE patterns with enrichments in Pt (5.7–46 ppb) and Pd (0.5–2.7 ppb) but with Os, Ir, and Ru abundances 20 that will produce rapid ingrowth of 186Os relative to 187Os. Deep recycling and storage of such subduction-modified rocks might preclude the need for core-mantle exchange to explain 186Os-enrichments in komatiites and Hawaiian picrites originating in the deep mantle ( Brandon et al., 1998 , Brandon and Walker, 2005 ).

We present in-situ zircon laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb ages, whole-rock geochemistry, and Sr–Nd–Pb–Hf isotopes of the Mugagangri monzogranite in the southern margin of the Qiangtang Block, Tibet, western China. The zircons yield a U–Pb age of ca. 123 Ma. The hornblende-bearing monzogranite shows metaluminous to weak peraluminous and high-K calc-alkaline characteristics exemplified by high silica (SiO2 = 67.57–70.57 wt%), high aluminium (Al2O3 = 14.68–15.78 wt%), high potassium (K2O = 4.00–5.14 wt%), high alkali (K2O + Na2O = 7.88–8.62 wt%), and low calcium contents (CaO = 1.72–2.17 wt%), with the aluminium saturation index (A/CNK) ranging from 0.98 to 1.09, suggesting that the Mugagangri monzogranite is a metaluminous to weak peraluminous I-type high-K calc-alkaline granite. Geochemically, similar to the arc magmas, the monzogranite is enriched in large-ion lithophile elements, and relatively depleted in high-field-strength elements. The monzogranite displays relatively high(87Sr/86Sr)i values (0.70972–0.71240), uniform eNd(t) values (−2.24 to −3.40), variable zircon eHf(t) values (−14.1 to +8.0), and high radiogenic Pb isotopic values (206Pb/204Pb = 18.588–18.790, 207Pb/204Pb = 15.616–15.642, and 208Pb/204Pb = 38.838–39.053). These geochemical characteristics indicate that the monzogranite was derived from a mixed source comprising ancient crustal and mantle materials, and experienced frac- tional crystallization during emplacement. We propose that the parental magma of the Mugagangri monzogranite was most likely generated during northward subduction of the Bangong Coujiang Meso-Tethys Ocean.

The Jiaodong Peninsula is one of the most important Au ore provinces in China. There is an ongoing debate on the correlation between ore formation and magmatism in this province, because few intrusive rocks exhibit a clear association with ore deposits. A mineralized biotite monzodiorite (BM) stock, with disseminated ore, pervasive phyllic alteration, and no deformation, was found in a borehole in the footwall of the Zhaoping fault within the Luanjiahe Au deposit, which may shed light on this debate. The biotite monzodiorite contains explosion breccias, miarolitic cavities, skeletal and dendritic quartz, and late-stage evolved aplite dikes, and the in-situ δ34S values of the disseminated pyrite which is associated with Au mineralization are −1.7‰ to 7.3‰ (mean=3.5‰), indicative of a magmatic-hydrothermal system. These findings, combined with the reported age of 123 Ma, show that the intrusion has close spatial, temporal, and geochemical relationships with Au mineralization in the area. The biotite monzodiorite is metaluminous, high-K calc-alkaline and shoshonitic, with enrichment in light rare earth elements (REEs) and large-ion lithophile elements (LILEs), depletion in high-field-strength elements (HFSEs), and enriched Sr-Nd isotopic compositions. The intrusion may be the product of partial melting of enriched lithospheric mantle with a small lower crustal component. The hydrous, Au-bearing, enriched mantle source, and the strongly oxidized magma that was generated, created favorable conditions for Au mineralization.

The Manzhouli–Xin Barag right banner are located in the southwest of the Ergun Massif (NE China), the tectonic evolution of these areas are still controversial. In this study, a series of rocks comprising rhyolites (LA–ICP–MS U–Pb zircon ages of 206 ± 2 Ma and 195 ± 2 Ma), granodiorites (196 ± 1 Ma and 190 ± 1 Ma), and monzogranites (206 ± 5 Ma and 196 ± 1 Ma) are newly identified. Whole-rock major and trace element analyses show that these felsic rocks and granites belong to the metaluminous to peraluminous, high-K calc-alkaline series, and can be classified as I-type granites. The zircon in-situ Lu–Hf isotope analyses on rhyolite, granodiorite, and monzogranite, yielded the eHf(t) values that are ranging from of 9.7–12.1, and two-stage model age are in the range of 0.5 Ga to 0.6 Ga, eHf(t) values of 4.4–7.5, 0.8–1.0 Ga, eHf(t) values of 6.0–10.5, 0.6–0.9 Ga, respectively. The whole-rock Sr–Nd isotope analyses on rhyolite, granodiorite, and monzogranite, yielded lower initial 87Sr/86Sr ratios (ISr) of 0.703374–0.703586, 0.704503–0.704577, 0.704936–0.704379, with medium eNd(t) values of 4.32–4.38, 1.54–2.96, − 0.68 to 2.73, respectively, suggesting that they are derived from the partial melting of a juvenile depleted lower crust. They all show enrichment in the large ion lithophile elements (e.g., Rb, Ba, and K) and depletion in the high field strength elements (e.g., Nb, Ta, and Ti), indicating that they are generated in an Andean-type arc setting and are metasomatized by subduction-slab released fluids or melts with minor crustal contamination. Mainly three magmatic phases: ca. 283–225 Ma, ca. 225–166 Ma, and ca. 166 Ma–114 Ma are identified in the Ergun Massif, and above Late Triassic to Early Jurassic magmatic rocks are related to the second phase, which attribute to the Mongol–Okhotsk ocean southward subduction and lateral crustal growth.

A large number of Au polymetallic deposits have been mined in the Jiangnan Transition Belt (JTB), Eastern China. However, the formation and genesis of these Au polymetallic deposits remain unclear. Based on geochronological, geochemical, in-situ Lu–Hf and S isotopic compositions of the Yucun Au deposit, combined with other Au deposit databases in the JTB (e.g., Zhaceqiao, Zhaojialing and Huashan), this study systemically reveals the petrogenesis of the granodiorite porphyries and granite porphyries related to gold deposits, as well as constrain the process of Au mineralization. Results show that all granodiorite porphyries and granite porphyries have high alkalis content and FeO/MgO ratios, low CaO, Al2O3, P2O5 and 10000 × Ga/Al contents, indicating the I-type granite affinity. Moreover, they are enriched in large ion lithophile elements (LILEs), light rare earth elements (LREEs) and depleted in high field strength elements (HFSEs) and heavy rare earth elements (HREEs), with weak negative Eu anomalies. Zircon 206Pb/238U ages indicate that the Yucun ore-related intrusion rocks were emplaced ca.150 Ma, which are consistent with the first stage magmatic activity in eastern China. The Yucun intrusion rocks present high zircon Ce4+/Ce3+ and Eu/Eu∗ ratios, suggesting the high magmatic oxygen fugacity, which is conducive to the Cu–Au mineralization. The geochemical and Lu–Hf isotopic compositions indicate that intrusion rocks associated with Au deposit in JTB may come from the metasomatized mantle-derived magmas mixing with Proterozoic crustal materials. The δ34S values of pyrite of ores in Yucun Au deposit indicate a magmatic-derived source, resembling in other porphyry-skarn Au deposits in the JTB.

O Batólito Catolé do Rocha, situado no Domínio Rio Piranhas-Seridó da Província de Borborema (Nordeste (NE) do Brasil), é um importante representante do magmatismo ediacarano pós-colisional que acometeu essa região. Ele inclui sienogranitos e quartzo sienitos metaluminosos a ligeiramente peraluminosos, rochas básico-intermediárias e, subordinadamente, diques e/ou bolsões de microgranitos menores. Esse batólito é tido como representante da suíte cálcio-alcalina de alto K, que inclui principalmente granitos de afinidade química próxima aos de tipo-I caledonianos. Contudo, são diversas as evidências litoquímicas que aproximam o batólito aos magmas de tipo-A. As rochas graníticas são álcali-cálcicas a alcalinas, possuem caráter ferroano, concentrações significativas de elementos litófilos de raio grande (LILE) e de alto potencial iônico (HFSE) e enriquecimento de terras-raras leves (LREE) sobre pesados (HREE). Suas assinaturas químicas permitem classificá-los como granitos de tipo‑A2 pós-colisionais. Estimativas geotermobarométricas apontam cristalização sob pressões de 4,6 – 6,3 kbar (~16 – 24 km de profundidade) e temperaturas entre 950 – 750°C, em condições de baixa fugacidade de oxigênio (-4 < ΔQFM < -1). Evidências químicase distintas condições redox estimadas para os granitos e rochas básico-intermediárias do batólito sugerem que se trata de magmas distintos, com misturas do tipo mixing e mingling locais. A origem do batólito parece estar relacionada a fontes enriquecidas (metassomatizadas), com diferenciação controlada principalmente por processos de cristalização fracionada.

—Alkaline and subalkaline granites of the Keivy megablock belong to the potassic alkali-calcic ferroan rocks enriched in large-ion lithophile, high-field strength and rare-earth elements. Based on these criteria, they correspond to A2-type granites (Eby, 1992). The granites have elevated Y/Nb (1.9–2.5) and Yb/Ta (3.4–3.7) ratios typical of crustally derived granites. The initial 176Hf/177Hf ratios in the central parts of zircon crystals vary within 0.281004–0.281175 at eHf(T) ranging from –2.89 to 3.79. It is supposed that the underplating of high-temperature mafic melts caused melting of metasomatically altered lower-crustal rocks and formation of palingenetic lower-crustal melts, which during subsequent ascent in the upper crust experienced fractional crystallization to more siliceous subalkaline and alkaline melts.

In 2003, Railsback proposed the Earth Scientist’s Periodic Table, which displays a great deal of elemental geology information in accordance with the natural environment of the earth. As an applied science, metallurgy is based on mineral composition and element behavior, that is similar to geochemistry. In this paper, connections and similarities between geology and metallurgy are identified, based on geochemical laws and numerous metallurgical cases. An obvious connection is that simple cations with high and low ionic potential are commonly extracted by hydrometallurgy, while those with intermediate ionic potential are extracted by pyrometallurgy. In addition, element affinity in geology is associated with element migration in metallurgic phases. To be specific, in pyrometallurgy, lithophile elements tend to gather in slags, chalcophile elements prefer the matte phase, siderophile elements are easily absorbed into metal melt, and atmophile elements readily enter the gas phase. Furthermore, in hydrometallurgy, the principles of hard/soft acids and bases (HSABs) offer an explanation of how precipitation and dissolution occur in different solutions, especially for fluoride and chloride. This article provides many metallurgical examples based on the principles of geochemistry to verify these similarities and connections.

The mechanism for generation of Silurian-Devonian hornblende-bearing I-type granitoids in the Chinese Altai still remains rather obscure. The possibility that they are derived from the regional anatexis of the Ordovician accretionary wedge, i.e., the Habahe Group, is investigated. The Habahe Group contains a large number of intermediate-to-basic components. These components occur mainly as interlayered volcanogenic bands or admixtures and less commonly as blocks varying in size from several meters to several hundreds of meters. Geochemically, this volcanogenic component is characterized by enrichment of large-ion lithophile elements relative to many of the high-field strength elements and rather radiogenic Nd isotopic signatures (eNd(t): +4.1 to +9.1). Phase equilibrium and trace element modelling indicate that partial melting of the volcanogenic component at an attainable 900–1000 °C can produce 30–35 vol% silicic melts that show a good chemical match, in terms of major element contents and trace element patterns, with those of the local I-type granitoids. Combined with regional available data, we suggest that Silurian-Devonian hornblende-bearing I-type granitoids could be derived from the partial melting of the volcanogenic components of the Habahe Group and previously inferred large input of mantle-derived magma is un-necessary. Regional anatexis of the Ordovician accretionary wedge led to the stabilization of the wedge, which may represent an important mechanism contributing to the formation of vertically stratified continental crust in accretionary orogens in general.

The South China Block (SCB) consists of the Yangtze and Cathaysia Blocks which, in the northeast, are separated from each other by the Jiangnan Orogen. The southward continuation of the Jiangnan Orogen into the Youjiang Basin remains much debated. Here, we present detailed petrological, chemical and isotope evidence from the Late Jurassic (~159 Ma) Yangtun and Liuliang high-Mg andesites (HMA), eastern Youjiang Basin, to place important constraints on an ancient subduction event. These HMA are enriched in large ion lithophile elements and depleted in Nb-Ta-Ti, with negative whole-rock eNd(t) and zircon eHf(t) values, similar to Neoproterozoic high-Mg rocks that occur in the eastern Yangtze Block. Considering the distance of our study areas to penecontemporaneous Pacific or Tethyan trenches, we infer that these HMA derived from a metasomatised lithospheric mantle preserved beneath the eastern Yangtze Block, which was associated with a Neoproterozoic subduction event. The Late Jurassic HMA in the eastern Youjiang Basin provide potential clues for the southward continuation of the Jiangnan Orogen into the basin.

International audience; The core – mantle differentiation in the magma ocean constitutes a major planetary event that involved two elements that are essential to life: carbon (C) and hydrogen (H). These two elements are conventionally classified as volatiles (ie. atmophile), but they can also evolve into being siderophile and lithophile at the extreme conditions found in planetary magma oceans. We report here a model for H and C species dissolved in silicate melts in equilibrium with iron-rich alloys under variable pressure, temperature and redox conditions. This speciation model is able to reconcile and reproduce a large body of experimental data on metal-silicate partitioning for H and C at carbon-saturation and in C-undersaturated systems. At low pressure, we conclude that the prevailing species in a silicate magma ocean are CO2, CO, H2O, H2, whereas CH4 appears to dominate at high pressure. These speciation changes explain recent experimental observations that (i) C evolves from being strongly siderophile at low pressure to moderately siderophile at high pressure, and (ii) H is not siderophile at low pressure but becomes increasingly so as pressure rises. Moreover, it shows that H becomes increasingly siderophile as the total H content of the silicate melt and C-activity are lowered. Despite it offers a promising reconciliation of a large set of experimental and molecular dynamics observations, this model still suffers from large uncertainties when extrapolated to high pressure. In particular, endmember and mixing properties in both the silicate melt and the molten metal must be independently deciphered.The enhanced CH4 stability in the silicate melt at high pressure couples the fate of C and H in deep magma oceans. In such cases, the solubility of C in the basal ocean depends on the H-content and is higher than C-solubility at low pressure. This implies an increase in C activity as the ascending convective cells of the magma ocean, which may cause C saturation as graphite or diamond unless Fe-metal droplets, having a great C-solubility, are present in the shallow magma ocean. Under certain conditions, enhanced siderophile behaviour for H can lead via a runaway process to the desiccation of the magma ocean.

We report U–Pb dating of zircon, as well as geochemical and Hf isotope data, in order to constrain the formation time, magma source, and tectonic setting of granite porphyry dykes in the Xicha gold–(silver) district in southern Jilin Province, Northeast China. The zircon grains are euhedral–subhedral, display oscillatory growth zoning and have Th/U ratios varying between 0.11 and 0.78, which together imply a magmatic origin. The dating results indicate the porphyry formed in the Early Cretaceous (122 ± 1 Ma), and it contains SiO2 = 70.64–72.31 wt%, Al2O3 = 13.99–14.64 wt%, K2O + Na2O = 6.96–7.81 wt%, K2O/Na2O = 1.24–2.10, and A/CNK = 1.11–1.41. Chemically, the porphyry belongs to a high-K calc-alkaline S-type granite. Chondrite-normalized rare earth elements (REE) patterns show LREE enrichment, light rare earth elements (LREE)/heavy rare earth elements (HREE) = 9.93–11.97, (La/Yb)N = 11.08–15.16, and δEu = 0.69–0.95. On the trace element spider diagram, large ion lithophile elements such as Rb, Ba, K, Th, and U are enriched, whereas the high field strength elements Ti and P are depleted. The eHf(t) values of zircon from the granite porphyry vary between − 17.1 and − 13.2, and their Hf two-stage model ages vary from 2.01 to 2.26 Ga, implying that the magma was derived from partial melting of old lower crust. The granite porphyry dykes and many A-type granites in the region formed at the same time, suggesting an extensional environment. The combination of the occurrence of strong magmatism, large-scale mineralization, and extensional tectonics throughout much of Eastern China indicate that the Early Cretaceous was a period of significant lithospheric thinning. The southern Jilin Province, therefore, experienced lithospheric thinning during the Early Cretaceous.

Petrology, whole-rock geochemistry, in situ zircon U–Pb ages, and Lu–Hf isotopic data are reported for granodiorite and monzonitic granite samples from the Harizha Region in the eastern section of the East Kunlun Orogenic Belt. The results of the LA-ICP-MS zircon dating indicate that the granodiorite and monzonitic granite were emplaced at 447.9 ± 3.0 Ma and 443.8 ± 3.5 Ma, respectively, i.e., in the Late Ordovician–Early Paleozoic periods. The granodiorite is characterized by relatively high MgO (4.52–5.91 wt%), Sr (541–712 ppm), Cr (218–357 ppm), Ni (56.7–80.7 ppm) and V (66.8–94.7 ppm), with low Y (10.40–13.60 ppm) and Yb (1.05–1.45) contents. This results in elevated Mg# (65–68), Sr/Y (39.78–58.84), and (La/Yb)N (10.21–18.30) ratios, common features for adakitic high-Mg andesite (HMA). The granodiorite is metaluminous to weakly peraluminous and high-K calc-alkaline in composition. In addition, the granodiorite is enriched in light rare-earth elements (LREE) and large ion lithophile elements (LILEs, Rb, K, Sr, and Pb) U, and Nd; and depleted in high-field strength elements (HFSEs, Nb, Ta, Zr, Hf, Ti) and P. The zircon grains from the granodiorites have eHf(t) values of − 5.5 to + 4.7, with two-stage Hf model ages (tDM2) ranging from 0.92 to 1.71 Ga. These features suggest that the granodiorites were formed by mixing processes of crustal melts and magma from a metasomatized mantle in a subduction setting. The monzonitic granite possesses high normative corundum values (2.34–4.10 wt%), is strongly peraluminous (A/CNK ratios of 1.16–1.32, with minor mineral muscovite), with high-K calc-alkaline affinity. Furthermore, enrichments in large ion lithophile elements (Rb, K, and Pb), U, Th, and Nd, depletions in high-field strength elements (Nb, Ta, and Ti) and Ba and P, and mainly right-inclined REE patterns with negative Eu anomalies, exhibits an S-type granite affinity. The magmatic zircons from the monzonitic granite yielded eHf(t) values between − 4.9 and − 2.7, corresponding to two-stage Hf model ages of 1.60–1.73 Ga. Therefore, this study suggests that the monzonitic granite magma was derived from crustal material (metagreywacke) in a syn-collision setting. Subsequently, by combining these findings with the previous research results, this study propose that a transverse diachronism closure model which entailed an “earlier on the sides–later in the middle” in an East–West direction in the East Kunlun Orogenic Belt for the Proto-Tethys Ocean’s evolution process.

Large (>3.5 mm and up to 4 cm across) igneous inclusions poor in metal and sulfide are a minor but not uncommon component in ordinary chondrites, and have implications for the nature of physiochemical and melting processes in the early solar system. We obtained petrographic-chemical data for forty-two large igneous inclusions in ordinary chondrites of various groups (H, L, LL) and petrographic types (3-6) and oxygen isotope data for a subset of twelve of these inclusions and their host chondrites. Different inclusions formed both before and after the thermal metamorphism experienced by their host chondrites. The bulk chemical compositions of the inclusions vary broadly around whole-rock chondrite composition, comprise four main chemical types and some other variants, and show little evidence of having formed as igneous differentiates. Oxygen isotope compositions overlap ordinary chondrite compositions and are related to inclusion chemical type. Most prevalent in type 3 and 4 chondrites are inclusions, often droplets, of the vapor-fractionated (Vfr) chemical type, either enriched in refractory lithophile elements, or depleted in volatile lithophile elements, or both. These inclusions have low Δ17O (∼0.1-0.6‰) and high δ18O (∼4-8‰) values and formed in reservoirs with Δ17O lower than their hosts, primarily as evaporative melts and mixtures that probably experienced kinetic isotopic fractionation. Another chemical type (Unfr+K) has unfractionated abundances of lithophile elements except for being strongly enriched in K, a signature also found in some impact melts from melt rocks and melt breccias. These inclusions formed by impact melting of chondritic material and accompanying K enrichment. Inclusions with unfractionated (Unfr) lithophile element abundances are present in type 3-6 chondrites and are prevalent in type 5 and 6. Some are spatially associated with coarse metal-sulfide nodules in the chondrites and likely formed by in situ impact melting. Others were melted prior to thermal metamorphism and were chemically but not isotopically homogenized during metamorphism; they are xenoliths that formed in oxygen reservoirs different than the hosts in which they were metamorphosed. The latter inclusions provide evidence for nebular or collisional mixing of primitive materials prior to thermal metamorphism of asteroid bodies, including transport of H-like source materials to the L body, LL-like source materials to the L body, and low-Δ17O materials to the LL body. Feldspar-rich (FldR) inclusions have compositions similar to melt pockets and could have formed by disequilibrium melting and concentration of feldspar during an impact event to form large droplets or large masses. Overall, the results of this study point to important and varied roles for both “planetary” impact melting and “nebular” evaporative melting processes to form different large igneous inclusions in ordinary chondrites. Chondrules may have formed by processes similar to those inferred for large inclusions, but there are important differences in the populations of these objects.

This study evaluates the adsorption capacity of syngenetically modified lignin-derived biochar for chalcophile (zinc, Zn), siderophile (copper, Cu) and lithophile (manganese, Mn) ions in si...

In recent years, cryoconite has received growing attention from a radioecological point of view, since several studies have shown that this material is extremely efficient in accumulating natural and anthropogenic radionuclides. The Novaya Zemlya Archipelago (Russian Arctic) hosts the second largest glacial system in the Arctic. From 1957 to 1962, numerous atmospheric nuclear explosions were conducted at Novaya Zemlya, but to date, very little is known about the radioecology of its ice cap. Analysis of radionuclides and other chemical elements in cryoconite holes on Nalli Glacier reveals the presence of two main zones at different altitudes that present different radiological features. The first zone is 130–210 m above sea level (a.s.l.), has low radioactivity, high concentrations of lithophile elements and a chalcophile content close to that of upper continental crust clarkes. The second zone (220–370 m a.s.l.) is characterized by high activity levels of radionuclides and “inversion” of geochemical behaviour with lower concentrations of lithophiles and higher chalcophiles. In the upper part of this zone (350–370 m a.s.l.), 137Cs activity reaches the record levels for Arctic cryoconite (5700–8100 Bq/kg). High levels of Sn, Sb, Bi and Ag, significantly exceeding those of upper continental crust clarkes, also appear here. We suggest that a buried layer of contaminated ice that formed during atmospheric nuclear tests serves as a local secondary source of radionuclide contamination. Its melting is responsible for the formation of this zone.

The basalts of the Sangxiu Formation are widely distributed across the Nagong area of southern Tibet, particularly along the Rongbu–Gudui fault and its secondary faults. High-precision testing and analysis of the basalts reveal SiO2 contents ranging from 43.7 to 47.71%, and initial 87Sr/86Sr and 143Nd/144Nd ratios of 0.706135–0.708093 and 0.512521–0.512706, respectively; eNd(t) values are − 1.18 to + 2.57. These data are consistent with the characteristics of ocean island basalts (OIB) and Emeishan high-Ti basalts. Large ion lithophile elements (LILEs) such as Rb and Ba, as well as high field strength elements (HFSEs) such as Nb, Ta, and Zr, are enriched, and there is no obvious Eu negative anomaly. These results indicate that the Sangxiu basalts are OIB-type alkaline basalts formed through interactions with the lithospheric mantle as well as partial melting of the asthenospheric mantle in relation to a mantle plume. Additional comparative analysis of the regional Cuomei Large Igneous Province (CLIP) and other rocks related to the Kerguelen hotspot suggests that the Nagong basalts belong to the CLIP in relation to the earliest Kerguelen hotspot activity.

Dulaankhan granitic pluton, which is situated in northern Mongolia, the southern portion of the Mongolian-Transbaikalian belt (MTB), is petrographically composed of fine to medium-grained peralkaline granite and is intruded by a small body of quartz syenite. Geochemical data show the Dulaankhan granite and the intruding quartz syenite are both slightly peraluminous and high-K calc-alkaline, and are enriched in LREEs relative to the HREEs, with negative Eu anomaly, and in large ion lithophile elements (LILEs; such as K, Cs and Rb) with respect to high field strength elements (HFSEs; e.g., Nb, Ta and Ti). In terms of relations of Nb, Zr and Y to Ga/Al, however, the Dulaankhan granite and quartz syenite show geochemical features of A-type granites and can be classified into the A2-sub type granite, implying that the pluton formed in an post-collision extensional environment. LA-ICPMS zircon U-Pb dating results suggest that the Dulaankhan granite crystallized at 198±1 Ma, whereas the intruding quartz syenite at 180±1 Ma, consistent with our field observation that the quartz syenite intrudes the granite, attesting that the two granitic bodies were emplaced at different times although both of them formed during the Early Jurassic period. According to these new data, as well as regional ones, we propose that the Dulaankhan granitic pluton was likely generated in the post-collision setting related to the orogenesis of the Mongol-Okhotsk belt that seems to occur prior to Early Jurassic in the northern Mongolian segment.

The article presents the results of a study of the composition of xenoliths of mantle peridotites (seven samples), collected from the Quaternary basalts of the Sverre volcano, the Svalbard archipelago. The presence of two big (more than 15 cm in diameter) xenoliths of spinel lherzolite allowed us to consider a change in their composition in the cen- tral, intermediate, and marginal parts of the samples. It is proposed to distinguish three types of xenoliths by the distribution of trace and rare earth elements. Enrich- ment of mantle peridotites with light rare earth elements, as well as high field strength (HFS) and large-ion lithophile (LIL) elements, is presumably associated with mantle metasomatism.

Whole-rock and Sr–Nd–Pb isotopic composition data, zircon Hf isotopic data and zircon U–Pb ages were obtained for the Late Triassic porphyries in the Zhongdian arc, eastern Tibet. These porphyries are intermediate and metaluminous and are enriched in large ion lithophile elements and depleted in high field strength elements. Moreover, they have weak negative Eu anomalies, high Sr and Ba contents, and high Sr/Y ratios. Different mineral geothermobarometers suggest that the porphyries in the Zhongdian arc crystallized atc. 640–829 °C and pressures of 2.1–2.8 kbar at depths shallower than 8 km. The porphyries have a calculated water content of 4.47–4.94 wt % and a relatively high magmatic oxygen fugacity. These porphyries were emplaced mainly at 230–203 Ma with a peak at 218–215 Ma. The Sr–Nd–Pb–Hf isotope data suggest that the porphyries in the Zhongdian arc were derived from a mixed melt of 50–65 % asthenospheric mantle and 35–50 % eclogite from the western Yangtze lower crust that experienced low-degree partial melting of 2–10 %. Subsequent fractional crystallization resulted in the decreasing trends of the major- and trace-element contents. The high Sr/Y and La/Yb values are the result of the low degree of partial melting of the western Yangtze lower crust rather than fractional crystallization, because no linear relationship was noted between Sr/Y or La/Yb and SiO2. The mixed melts from the lower crust and asthenospheric mantle provided a fertile magma source, and subsequent fractional crystallization under the favourable magmatic conditions of high water content and high oxidation state resulted in the formation of the porphyry Cu–Au deposits.

The lithophile elements and isotopic compositions of oceanic basalts suggest they derive from different mantle components. We present new analytical results of un-degassed deep-marine basaltic glasses from various regions, and we find strong linear correlations of R2 ≥ 0.997 between H2O and F as well as H2O and Ce, for which we propose mantle trends. The mantle trends represent global variations of mantle components, ranging from a depleted dry peridotite of mid-ocean ridge basalt (MORB) (DMM, depleted MORB source mantle: H2O = 100 ppm; H2O/Ce = 200; H2O/F = 10) to a hydrous peridotite of Hawaiian ocean island basalt (OIB) of deep mantle origin (FOZO, focal zone: H2O = 750 ppm; H2O/Ce = 200; H2O/F = 18.5). Accordingly, we defined the correlation as a volatile DMM–FOZO trend. Based on our findings, we report novel H2O–F–Ce systematics to discriminate the degree of water depletion in the source mantle and the rehydration of the mantle with recycled surface water through oceanic plate subduction. Using this method, most OIBs are distinguished clearly from the DMM–FOZO trend, and we find that the water in their sources originates from recycled water derived from the hydrated oceanic crust and sediment after various degrees of dehydration (75–95%) in subduction zones.

We performed a petrologic, geochemical, and oxygen isotopic study of the lowest FeO ordinary chondrite, Yamato (Y) 982717. Y 982717 shows a chondritic texture composed of chondrules and chondrule fragments, and mineral fragments set in a finer-grained, clastic matrix, similar to H4 chondrites. The composition of olivine (Fa11.17 ± 0.48 (1σ)) and low-Ca pyroxene (Fs11.07 ± 0.98 (1σ)Wo0.90 ± 0.71(1σ)) are significantly more magnesian than those of typical H chondrites (Fa16.0-20, Fs14.5-18.0), as well as other known low-FeO OCs (Fa12.8-16.7; Fs13-16). However, the bulk chemical composition of Y 982717, in particular lithophile and moderately volatile elements, is within the range of OCs. The bulk siderophile element composition (Ni, Co) is within the range of H chondrites and distinguishable from L chondrites. The O-isotopic composition is also within the range of H chondrites. The lack of reduction textures indicates that the low olivine Fa content and low-Ca pyroxene Fs content are characteristics of the precursor materials, rather than the result of reduction during thermal metamorphism. We suggest that the H chondrites are more compositionally diverse than has been previously recognized.

The South Qinling Belt was located in the northern part of the Yangtze Block during the Neoproterozoic. Here we investigate two major magmatic intrusions in the northern and southern part of the belt, the Douling plutons (DLP) and the Fenghuangshan plutons (FHSP), to gain insights into the Neoproterozoic tectonic processes along the northern segment of the Yangtze Block. Zircon grains in the DLP yield weighted mean 206Pb/238U ages of 750–709 Ma, whereas those from the FHSP show ages of 749–728 Ma. The new results, together with the published data, reveal that these plutons were emplaced at ca. 759–685 Ma and ca. 802–704 Ma, respectively. Geochemically, the intermediate-felsic rocks from the DLP and FHSP show enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE) (Rb, Ba and K), depletion of high field strength elements (HFSE) (Nb, Ta, P and Ti), and low Sr/Y and (La/Yb)N values, which are typical features of arc magmatic rocks. The gabbros from the FHSP have high Mg#, and display LREE and LILE (Rb, Ba, K, and Sr) enrichment and depletion of HFSE (Th, U, Nb, Ta, and Ti), suggesting that they were probably formed in a mantle wedge setting. Both DLP and FHSP show arc-related geochemistry modified by slab-derived fluids, and were formed at relatively high-temperature and low-pressure conditions. However, they display distinct Sr-Nd-Hf isotopic compositions. Zircon grains of two samples from the DLP respectively show mean eHf(t) values of −2.6 ± 0.3 and 0.9 ± 0.3, whereas zircon grains of four samples from the FHSP show mean eHf(t) values ranging from 7.5 ± 0.5 to 8.7 ± 0.4. The DLP shows dominantly negative eNd(t) values and inconsistent initial 87Sr/86Sr ratios, whereas FHSP shows relatively constant and positive eNd(t) values (3.69–3.74) but variable initial 87Sr/86Sr ratios. The Sr-Nd-Hf isotopic and geochemical features suggest that the enriched mantle and crustal materials were involved in the magma evolution of the DLP, whereas the FHSP is characterized by significant juvenile components with a rising asthenospheric mantle source playing a key role. We propose a subduction-related setting for these intrusions, and envisage slab rollback during the Neoproterozoic.

The Himalayan leucogranites provide insights into the partial melting behavior of relatively deeper crustal rocks and tectono-magmatic history of the Himalayan Orogen. The Paiku leucogranites of northern Himalaya can be subdivided into two-mica leucogranite (TML), garnet-bearing leucogranite (GL), cordierite-bearing leucogranite (CL), and tourmaline-bearing leucogranite (TL). All of them are high-K, peraluminous, calc-alkalic to alkali-calcic rocks. They are enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE), and show pronounced negative anomalies of Sr, Ba, K and Ti, but positive anomalies of Nb and Rb. LA-ICP-MS U-Pb zircon dating of one TML, one GL, and two CL samples yielded variable 206Pb/238U ages ranging from 23.6 to 16.1 Ma, indicating the Paiku leucogranites underwent a low degree of partial melting process. Combining with previous studies, we suggest the Paiku leucogranites were derived from partial melting of metasedimentary rocks of the Higher Himalayan Sequence (HHS). The GL and TL mainly resulted from the muscovite-dehydration melting, whereas the TML and CL were mainly derived from the biotite-dehydration melting. Finally, it is concluded that the Paiku leucogranites were probably formed during the subduction of the Indian crust.

There are ongoing concerns regarding environmental emissions of trace elements (TEs) from bitumen mining and upgrading in the Athabasca Bituminous Sands Region (ABSR). Depending on their physical and chemical forms, elevated concentrations of potentially toxic TEs in berries could pose a health risk to local indigenous communities because native fruits are an important part of their traditional diet. The objective of this study was to distinguish between aerial deposition of TEs versus plant uptake, in cranberries, lingonberries, and blueberries growing in the ABSR. The concentrations of TEs were determined using ICP-MS in the metal-free, ultraclean SWAMP lab at the University of Alberta. The spatial variation in abundance of conservative, lithophile elements such as Y in berries resembles the published map of dust deposition rates obtained using Sphagnum moss. The presence of dust particles on the surface of the berries near open pit mines and upgraders was confirmed using SEM. Elements which show strong, positive correlation with Y include Al, Cr, Pb, U, and V; these are supplied mainly by dust. Elements which are largely independent of Y concentrations include Ba, Cd, Cu, Mn, Mo, Ni, Rb, Sr, and Zn; these are obtained primarily by plant uptake from soil. The concentrations of elements associated with dust were considerably reduced after washing with water, but the elements independent of dust inputs were unaffected. Elements which are supplied almost exclusively by dust (e.g. Y) are more abundant in berries from the ABS region (2 to 24 times), compared to berries from remote locations.

International audience; Tungsten isotopes are the ideal tracers of core-mantle chemical interaction. Given that W is moderately siderophile, it preferentially partitioned into the Earth’s core during its segregation, leaving the mantle depleted in this element. In contrast, Hf is lithophile, and its short-lived radioactive isotope 182Hf decayed entirely to 182W in the mantle after metal-silicate segregation. Therefore, the 182W isotopic composition of the Earth’s mantle and its core are expected to differ by about 200 ppm. Here, we report new high precision W isotope data for mantle-derived rock samples from the Paleoarchean Pilbara Craton, and the Réunion Island and the Kerguelen Archipelago hotspots. Together with other available data, they reveal a temporal shift in the 182W isotopic composition of the mantle that is best explained by core-mantle chemical interaction. Core-mantle exchange might be facilitated by diffusive isotope exchange at the core-mantle boundary, or the exsolution of W-rich, Si-Mg-Fe oxides from the core into the mantle. Tung-sten-182 isotope compositions of mantle-derived magmas are similar from 4.3 to 2.7 Ga and decrease afterwards. This change could be related to the onset of the crystallisation of the inner core or to the initiation of post-Archean deep slab subduction that more efficiently mixed the mantle.

Tourmaline, one of the most important hosts of boron (B) in crustal rocks, has rarely been found in natural high-pressure (HP) and ultra-HP (UHP) eclogites. Here, we report the first finding of tourmaline-bearing UHP eclogites and veins in the Dabie terrane, China. These distinctive samples occur exclusively in impure UHP marbles. Investigations on the eclogite-vein-marble system provide important insights into the origin, flow, and metasomatic effects of eclogite-facies, 11B-rich fluids in continental subduction zones. Petrologic and geochemical evidence indicates that tourmaline in the eclogites (Tur-E) formed by metasomatism due to the infiltration of a B-rich fluid under conditions of ca. 2.2–2.6 GPa and 610–660 °C. The HP veins, containing euhedral tourmaline (Tur-V) and occurring at the eclogite-marble contacts or in the interiors of eclogite lenses, represent the crystallized products of the infiltrating fluid. Systematic compositional variations along the profile from the interiors of the eclogite lenses to their margins and mass-balance calculations indicate large inputs of B, carbon, large ion lithophile elements, and light rare earth elements to the eclogites during fluid infiltration. All types of tourmaline, including the Tur-E and Tur-V as well as minor amounts of tourmaline in the marbles (Tur-M), have similar compositions (dravitic) with XMg values [= Mg/(Mg + Fe)] of 0.7–0.8. In situ analyses using laser ablation multicollector inductively coupled plasma mass spectrometry show that all of tourmaline has high δ11B values (ranging from +6 to +15‰), which suggest a 11B-rich isotope signature for the infiltrating fluid. The tourmaline B isotope data, together with the detailed field observations and whole-rock Sr-Nd isotopes, reveal that the infiltrating fluid was derived from the impure marbles. Influx of such fluid was highly channelized and was mainly achieved along lithologic boundaries between UHP marbles and eclogites or along fractures in the eclogites. This study indicates that impure marbles are an important reservoir of isotopically heavy B in deeply subducted continental slabs. This point may be of particular importance because most B reservoirs in subducted continental crust typically have light B isotopic compositions. Our results highlight that subducted metacarbonate rocks could liberate eclogite-facies, B-rich, high-δ11B fluids and thus might exert important effects on the cycle of B and its isotopes in subduction zones.

Geochemical compositions of the Lower Cambrian Niutitang Formation shales in the southeastern Yangtze Platform margin were investigated for provenance, tectonic setting, and depositional environment. The shale samples are characterized by higher abundances of large ion lithophile elements (Cs, Ba, and Pb), lower abundances of high field strength elements (Cr, Sc, and Co) and transition elements (Th, Zr, Hf, Nb, and Ta) relative to average shale. North American shale composition (NASC) -normalized rare earth element (REE) patterns are observed, with negative Ce anomalies, negative Eu anomalies, and positive Y anomalies. The chemical index of alteration (CIA) varies from 68.67–74.93. Alkali and alkaline element contents and CIA values suggest that the source rocks have undergone moderate weathering. The index of compositional variability (ICV), Zr/Sc and Th/Sc ratios vary from 0.53 to 1.07, 5.31 to 8.18 and 0.52–1.02, respectively. ICV values and relationships between Zr/Sc and Th/Sc ratios indicate negligible sedimentary recycling. The Al2O3/TiO2 (14–26) and TiO2/Zr (56–77) ratios imply that the source rocks of the investigated shales had intermediate igneous compositions. However, Cr/V ratios and a La/Th–Hf discrimination diagram suggest that the intermediate compositional signal of the source rocks was derived from a mixture of 75% mafic and 25% felsic igneous rocks rather than intermediate igneous rocks. The major source was the Jiangnan continental island arc with bimodal igneous rocks, lying to the south of the study area, together with a contribution from granites and gneisses uplifted and eroded in the Yangtze Block. Discrimination of tectonic setting using major and trace elements indicates that the source rocks originated in a transitional setting from active continental to passive margin, consistent with the failed intracontinental rift model for the evolution of the South China plate. The Niutitang Formation shales were deposited in a rift basin setting under conditions of anoxic bottom water in a redox-stratified water column, with organic-rich shales prospective for shale-gas production being found in deep-water downslope and basin environments rather than the shallow-water shelf.

The NE–SW-trending Qin-Hang Belt and east–west-trending Nanling Range are two critical magmatic and mineralization zones in the southeastern South China Block (SCB). However, the formation timing and petrogenesis of the magmatism in these zones, along with the relationship with the Pacific subduction, remain hotly debated. Herein, this study presents a set of zircon U–Pb geochronological, Lu–Hf isotopic and whole-rock geochemical data for the Late Jurassic Mashan and Nandu shoshonitic intrusions in the Qin-Hang Belt. All the samples are enriched in large ion lithophile elements and light rare earth elements. They have high eNd(t) (from −1.4 to +4.4) and zircon eHf(t) values (from −1.0 to +3.4) and low initial 87Sr/86Sr (0.70426–0.70696), distinct from those of the Triassic shoshonitic rocks but comparable with those of the Jurassic shoshonitic rocks in the region. Such signatures suggest that the Mashan and Nandu igneous rocks mainly derived from a Jurassic metasomatized lithospheric mantle in response to asthenospheric upwelling, without significant contribution from subducted slab-derived components. Our new data, together with other geological observations, reveal a spatial change of magmatic activities, structural patterns, sedimentary basins and palaeocurrent directions during the Middle–Late Jurassic, probably associated with the far-field effects of the Pacific subduction in the interior SCB.

Magmatic rock plays a key role in controlling tectonics. By determining the chronology, petrogenesis and tectonic significance of newly discovered granite porphyry and granite units, this study documents the Bangong-Nujiang Neo-Tethys ocean evolution and the tectonic environment of the Zanzongcuo zone. Based on laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating of zircons, the ages of the granite porphyry and the granite are 113.74 ± 0.68 and 79.58 ± 0.83 Ma, respectively. Thus, these intrusive rocks formed at different times in the Cretaceous. The two studied intrusive bodies are I-type granitoids with peraluminous characteristics. The granite porphyry and the granite belong to the medium- to high-K calc-alkaline and low-K calc-alkaline series, respectively. These rocks are enriched in large ion lithophile elements (LILEs, e.g., Rb, U, and Th) and light rare earth elements (LREEs) but depleted in high field strength elements (HFSEs, e.g., Nb, Ta, and Ti). The granite porphyry and the granite have δEu values of 0.69–0.82 and 0.6–0.73, respectively, and have moderately negative Eu anomalies. The granite porphyry formed in a subduction-related structural environment and represents an arc-type granite. The granite formed in a collisional tectonic environment and represents a granite that formed in a within plate setting. The geochronologic and tectonic characteristics of these two intrusive rocks indicate that the Zanzongcuo zone experienced a series of tectonic events in the Cretaceous, including oceanic crust subduction in the late Early Cretaceous, continent-continent collision, and intraplate compression in the late Late Cretaceous. Furthermore, the Bangong-Nujiang Neo-Tethys ocean closed in the late Early Cretaceous.

The Ningzhen region of China is located in the easternmost part of the middle-lower Yangtze River Cu–Fe polymetallic metallogenic belt. From west to east, it comprises five main intermediate–acidic intrusive complexes: the Qilinmen, Anjishan, Xiashu–Gaozi, Shima, and Jianbi complexes. Geochemical investigations show that these five intrusive complexes exhibit high contents of SiO2, at 64.74–73.40 wt%, Al2O3, at 14.15–17.37 wt%, and K2O + Na2O, at 6.49–8.68 wt%. The majority of the samples belong to the high-K calc-alkaline series, with a few samples plotting in the calc-alkaline and tholeiitic series. Trace element analysis shows that the samples are enriched in large ion lithophile elements (LILE) and are depleted in high field strength elements (HFSE). The chondrite-normalized rare earth element (REE) patterns are characterized by right-inclined curves, showing light rare earth element (LREE) enrichment. In addition, the (La/Yb)N ratios are high at 15.02–37.28, with an average of 29.13, and slightly negative or none Eu anomalies are present. In the (La/Yb)N–δEu diagram, the samples plot within the crust-mantle type field. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb dating yielded ages of 122.0 ± 1.0 Ma, 106.1 ± 0.8 Ma, 108.7 ± 1.4 Ma, 103.5 ± 1.9 Ma, and 96.8 ± 1.7 Ma for the Qilinmen, Anjishan, Xiashu–Gaozi, Shima, and Jianbi complexes, respectively. On the basis of this research and knowledge of several known metal deposits related to these complexes, we suggest that the Mesozoic large-scale diagenesis and metallogenesis in the Ningzhen region may have ceased at 100 Ma or about 95 Ma.

Despite detailed geological studies on the Late Cretaceous Sabzevar ophiolites, the non-ophiolitic, subduction-related igneous rocks of NE Iran are still enigmatic. This paper focuses on the Late Cretaceous, non-ophiolitic Sabzevar magmatic rocks, and presents both precise U–Pb ages and a tectonomagmatic scenario for the genesis of these igneous rocks. A thick sequence of Late Cretaceous acidic volcanic rocks associated with sandstones, shales and pelagic limestones dominates the northern parts of the Lut block. This sequence is intruded by a series of shallow mafic to felsic intrusions. New zircon U–Pb results on the intrusive and extrusive rocks show ages of 75–101 Ma. These ages show a pulsed magmatism in NE Iran, which lasted for c. 25 myr. The whole-rock geochemistry of the igneous rocks shows suprasubduction-zone-related geochemical signatures, represented by negative anomalies in high field strength elements and enrichment in large ion lithophile elements. The initial 87Sr/86Sr ratios and eNd(t) values of the extrusive rocks range from 0.70411 to 0.70628 and from +5.9 to +7.4 respectively, and for intrusive rocks are in the range of 0.70423–0.70579 and +5.8 to +7.2. High eNd(t) values for these rocks confirm that their melts were derived from a depleted-mantle source. Both geochemical and isotopic data indicate that the genesis of these rocks was related to the partial melting of mid-ocean ridge basalt-type slab or depleted-mantle wedge sources during the northward movement of the Sabzevar oceanic slab beneath the southern edge of Eurasia (Turan block) in Late Cretaceous time.

The enriched basaltic (martian) shergottite Ksar Ghilane (KG) 002, discovered in 2010, is exceptionally rich in coexisting but discrete apatite and merrillite crystals. It has been selected to better constrain the formation conditions and post-crystallization processes, and thus the evolution of martian rocks based on Ca-phosphates. A petrological, chemical, chronological and microstructural approach using a series of high-spatial resolution techniques including Raman spectroscopy, electron microscopy (SEM, EPMA, CL-imaging) and secondary ion mass spectrometry (SIMS) analysis has been applied to a representative number of Ca-phosphate grains. Analytical results for apatite and merrillite reveal: (i) zoning in F, Cl, Br and I concentrations, (ii) elevated Cl concentrations in the range of ∼11,900–35,300 µg/g and halogen ratios, i.e., Cl/Br and Cl/I, as well as stable chlorine isotope composition, reported as δ37Cl values rel. to Standard Mean Ocean Chloride (SMOC, defined as 0‰) with a value of +0.67 ± 0.14‰ (1σ), distinguishing KG 002 phosphates from that of other enriched and depleted shergottites. The halogen and heavier δ37Cl record indicate a slightly higher degree of ∼3.5% assimilation of Cl-rich and isotopically heavier crustal reservoir on Mars when compared to other enriched shergottites. (iii) Structural investigations together with the chemical and petrological context of the grains confirm the occurrence of hydroxyl-poor merrillite, indicate weak if any alteration effects induced by metamictization, only minor structural modifications due to shock metamorphism, and absence of replacement reactions. Therefore, igneous crystallization of Ca-phosphates from a fractionated, hydrous and ferrous mantle source, rich in volatiles including the halogens and Na and lithophile rare earth-elements, and absence of interaction with crustal fluids/brines of the sample is deduced. (iv) The Pb isotopic composition of six apatite and three merrillite grains is highly unradiogenic and the 238U-206Pb record yields a phosphate crystallization time at 395 ± 240 Ma (2σ), which is similar to those of other enriched shergottites.

Paleoproterozoic mafic dikes from the Kongling Complex in South China provide an ideal opportunity to examine mantle properties and tectonic evolution of the Yangtze Block and thus to understand the paleo-position of South China in the Columbia supercontinent. The 2.0 Ga dikes are the oldest mafic intrusions identified in the Yangtze Block by far. Samples from the dikes consist of fine to medium-grained dolerite and have variable SiO2 (43.48–52.61 wt%) and MgO contents (3.17–7.35 wt%). They are enriched in LREE and show slightly negative to positive Eu anomalies (Eu/Eu∗ = 0.85–1.06). Their primitive mantle-normalized trace element patterns are characterized by enrichment of large-ion lithophile elements (Rb, Ba, Pb) and depletion of high-field-strength elements (U, Nb, Ta, Ti). Rocks from the dikes have variable initial 87Sr/86Sr ratios (0.698874–0.710753), eNd values (−3.0 to +4.1) and zircon eHf values (−2.7 to +3.4). These geochemical features indicate that their parental magmas were formed by

High–MgO basaltic lavas, including komatiites and picrites, have long been used as probes of both the chemical and thermal evolution of the mantle through time. The ca. 825 Ma Yiyang high–MgO basalts in the central South China Block (SCB) were considered to be the first evidence for >1500 °C mantle melts by a Rodinian mantle plume. However, later studies proposed that they may have been generated within an arc setting and can be classified as boninites. Here we present a comprehensive Os–Hf–Nd isotopic study of the Yiyang basalts. The Yiyang basalts have high MgO (>10%), Ni (>182 ppm), Cr (>667 ppm) and Os contents (mostly >0.3 ppb) with radiogenic Os isotopes ((187Os/188Os)i = 0.134 to 0.282). They have relatively uniform whole–rock Nd and Hf isotopes with eNd(t) and eHf(t) values ranging from −3.7 to −1.3 and from +2.9 to +4.3, respectively. Our new data indicate that although crustal assimilation and fractional crystallization (AFC) may have played a role in the geochemical diversity of the Yiyang basalts, the enrichment in light rare earth elements (LREE) and large–ion lithophile elements (LILE) relative to high field strength elements (HSFE) most likely are features of the primary magma. The Yiyang high–MgO basalts, along with contemporary high–MgO basalts in the central SCB, have lower SiO2 contents, and Al2O3/TiO2 ratios, but higher TiO2, Zr, Nb, and Nd contents and Th/U ratios than typical boninites. The presence of negative Ba anomalies and depletion in middle REE (MREE) to heavy REE (HREE) in these high-MgO basaltic rocks are also distinct from what is observed in typical boninites. Therefore, the primary magma of the Yiyang basalts had similar whole–rock geochemical compositions to that of komatiites and plume–derived basalts. Their decoupled Hf Nd isotopes indicate that recycled oceanic sediments may have been incorporated into their source. They have primitive mantle–like Al2O3/TiO2 ratios (21−23) and flat HREE patterns. However, unlike other Al–undepleted or Munro–type komatiites, their mantle source did not undergo earlier melting events. Our new results support the view that the Yiyang basalts are komatiitic and not boninitic, and that they were likely derived from a Rodinian mantle plume.

This study presents new thallium (Tl) concentration and isotopic composition data for potassium feldspar (K-feldspar), micas, sulfides, and other minerals using solution multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS). The samples studied represent a diverse set of igneous, metamorphic, and metasomatic rock types. Purified separates of minerals anticipated to be Tl-bearing were analyzed; in many cases coexisting minerals were measured to examine the distribution of Tl and its isotopes between coexisting phases. This study is the first of its kind to document mineralogical controls on Tl chemical and isotopic fractionation. Thallium contents in rock-forming minerals and common sulfides vary from below detection limit (here, approximately 0.2 ppm Tl in the mineral utilizing an IsoProbe MC-ICP-MS) to 3200 ppm. In this present study, mica and feldspar samples can reach Tl concentrations well over 20 ppm, compared to only 0.7 ppm in average crust. In contrast, only 14 of 38 common sulfide samples contain Tl at levels above the detection limit. Measured Tl isotope ratios, reported as e205Tl relative to the NIST 997 standard solution, range from −12.1 ± 0.6 to +18.0 ±1.4 (2σ). Most samples analyzed fall within the published range of e205Tl (−20 to +15) (Nielsen et al., 2017). Although most sulfides show limited Tl enrichment, they display the highest e205Tl values among coexisting minerals, with Fe-rich micas having the lowest e205Tl values. The patterns in enrichment are best interpreted to reflect crystal chemical differences and the incompatible, dominantly lithophile nature of Tl. In turn, isotopic fractionation also reflects control by the bonding environment as well as redox conditions. The preferential distribution of Tl into micas and K-feldspar found here is consistent with the similarity in charge and ionic radius of Tl+ and K+. The higher e205Tl values in sulfides agree with previous observations and theoretical studies showing the tendency of covalent bonds, high bond strengths, and high oxidation states to favor heavy isotopes. This work highlights important areas for future research regarding the natural weathering of Tl-bearing substrates, understanding regional cycling of Tl, and potential bioremediation of Tl contamination.

The Central Kunlun ophiolitic melange zone, northern Tibetan Plateau, represents a remnant of the Early Paleozoic oceanic lithosphere. The Middle Ordovician Longshigeng basalts (LBs) are located in south of this melange zone and have important significance for reconstructing the opening and subduction processes of the Proto-Tethys Ocean. This study presents petrological, whole-rock geochemical, and zircon U-Pb data for these basalts. LA-ICP-MS U-Pb zircon data indicate that these basalts formed ca. 463 Ma. Geochemically, the basalts are characterized by low SiO2 (47.00–50.63 wt%) and K2O (0.22–1.05 wt%), intermediate Mg# (47–57) and high TiO2 (1.51–2.72 wt%), and are identified as tholeiitic basalts. Their chondrite-normalized REE patterns feature slight enrichments in LREEs (LREE/HREE = 2.11–3.08) with mild Eu anomalies (δEu = 0.89–1.06), and their patterns are similar to the reference line of enriched mid-ocean ridge basalt (EMORB). The primitive mantle-normalized trace element diagrams also show similarities with EMORB and are characterized by overall enrichments in large ion lithophile and high field strength elements, without notable Nb, Ta, and Ti depletions. Combining these data with the tectonic discrimination diagrams, we infer that these rocks formed in a back-arc environment in response to the northward subduction of the Proto-Tethys Ocean (South Kunlun Ocean) in the East Kunlun region, northern Tibetan Plateau.

This paper presents a new detailed study including zircon U-Pb-Hf isotopic, whole-rock geochemical and Sr-Nd isotopic analyses of conglomerate and granitic pebbles from the molasse deposits in central Jilin Province, NE China. These data are used to better constrain the Late Permian–Triassic tectonic evolution regarding particularly the final closure of the Paleo-Asian Ocean (PAO) along the Changhun-Yanji suture (CYS). Zircon U-Pb data indicate that the granitic pebbles formed in the end-Permian (254–253 Ma). The youngest detrital zircon age of 231 Ma from the conglomerate, and presence of the overlying Upper Triassic Sihetun Formation suggests that the molasse deposits on the Jin′gui Island formed during the Late Triassic. The end-Permian granitic rocks display high SiO2 (66.07–74.77 wt %), with low MgO (0.55–2.05 wt %) and Mg# (31.61–43.64) values, together with depleted Hf and Nd isotopic values (εHf(t) = +1.61 to +11.62, εNd(t) = +3.3 to +4.2, (87Sr/86Sr)i = 0.706458–0.706842) and juvenile second-stage Hf model ages (1148–512 Ma), suggesting that they were probably generated by the partial melting of a Meso-Neoproterozoic juvenile metabasaltic lower crust. They are characterized by enrichments in large ion lithophile elements (LILEs) and depletions in high field strength elements (HFSEs), with affinities to igneous rocks forming in a subduction-related setting. This, combined with regional coeval subduction-related magmatic rocks, indicates that the PAO still existed along the CYS. In addition, the identification of Late Triassic molasse deposits on the Jin′gui Island in this study, coupled with occurrences of many Early Triassic syn-collisional granitoids along the CYS, indicates that the final closure of the PAO took place prior to the Late Triassic.

The study presents a complex characteristic of zircon from the Verkhneurmiysky intrusive series with Li-F granites. A wide range of morphological and chemical properties of zircon allowed us to obtain new information on the formation and alteration of zircon from biotite and zinnwaldite granitoids and to determine its features, which contribute to the correct definition of Li-F granites formed directly before the tin mineralization. The reviled trends of zircon morphology and composition evolution in the Verkhneurmiysky granites series are: the high-temperature morphotypes are followed by low-temperature ones with more complicated internal structure with secondary alteration zones, mineral inclusions, pores, and cracks, the increasing concentration of volatile (H2O, F), large ion lithophile (Cs, Sr), high field strength (Hf, Nb) and rare-earth elements with decreasing crystallization temperatures and the determining role of the fluid phase (predominantly, F) in the trace element accumulation. The composition of zircon cores in biotite and zinnwaldite granites is very similar. However, the zircon rims from zinnwaldite granites are much more enriched in trace elements compared to those from biotite granites. The first study of zircon from the Verkhneurmiysky granitoids provides new data on the formation and alteration conditions of granitoids, including zinnwaldite ones.

In biomonitoring of airborne elements with native lichens, two allopatric species could be used jointly only when bioaccumulation mechanisms are the same, and differences negligible. The present study aims at (i) investigating the bioaccumulation performance for 12 elements in one-year-old lobes of Flavoparmelia caperata and Xanthoria parietina (i.e. the two lichen native biomonitors most used in the peri-Mediterranean regions) collected side-by-side on the same trees at 17 sampling sites. Both species were characterized morphologically and by X-ray diffraction analysis to evaluate specific thallus area and oxalate content, respectively. Results show that Ca and chalcophile elements (Cd, Cu, Pb and Zn) were more concentrated in F. caperata, lithophile and siderophile elements (Cr, Fe, and Ti) in X. parietina, whereas Al, Li, Mn, and Ni were accumulated in similar amounts. The outstanding content of Ca-oxalate deposits in F. caperata underlies the higher content of Ca, Cd and Pb observed in this species. On the contrary, the micro-anatomy of the upper cortex of X. parietina, which is more porous than in F. caperata, allows a higher transfer of litophile and siderophile elements. The adoption of interspecific calibration factors for biomonitoring purposes is thoroughly discussed, and the choice of using a single native species made by the most recent guidelines for biomonitoring airborne elements with lichens is fully supported.

Detection of Hadean isotopic signatures within modern ocean island basalts (OIB) has greatly influenced understanding of Earth's earliest history and long‐term dynamics. However, a relationship between two isotopic tools for studying early Earth processes, the short‐lived 146Sm‐142Nd and 182Hf‐182W systems, has not been established in this context. The differing chemical behavior of these two isotopic systems means that they are complementary tracers of a range of proposed early Earth events, including core formation, magma ocean processes, and late accretion. There is a negative trend between 142Nd/144Nd and 182W/184W ratios among Réunion OIB that is extended by Deccan continental flood basalts. This finding is contrary to expectations if both systems were affected by silicate differentiation during the lifetime of 182Hf. The observed isotopic compositions are attributed to interaction between magma ocean remnants and Earth's core, coupled with later assimilation of recycled Hadean mafic crust. The effects of this scenario on the long‐lived 143Nd‐176Hf isotopic systematics mirror classical models invoking mixing of recycled trace‐element enriched (sedimentary) and depleted (igneous) domains in OIB mantle sources. If the core provides a detectible contribution to the tungsten element budget of the silicate Earth, this represents a critical component to planetary‐scale tungsten mass balance. A basic model is explored that reconciles the W abundance and isotopic composition of the bulk silicate Earth resulting from both late accretion and core‐mantle interaction. The veracity of core‐mantle interaction as proposed here would have many implications for long‐term thermochemical cycling., Geochemistry, Geophysics, Geosystems, 22 (3), ISSN:1525-2027

The noble gas isotope systematics of ocean island basalts suggest the existence of primordial mantle signatures in the deep mantle. Yet, the isotopic compositions of lithophile elements (Sr, Nd, Hf) in these lavas require derivation from a mantle source that is geochemically depleted by melt extraction rather than primitive. Here, this apparent contradiction is resolved by employing a compilation of the Sr, Nd, and Hf isotope composition of kimberlites-volcanic rocks that originate at great depth beneath continents. This compilation includes kimberlites as old as 2.06 billion years and shows that kimberlites do not derive from a primitive mantle source but sample the same geochemically depleted component (where geochemical depletion refers to ancient melt extraction) common to most oceanic island basalts, previously called PREMA (prevalent mantle) or FOZO (focal zone). Extrapolation of the Nd and Hf isotopic compositions of the kimberlite source to the age of Earth formation yields a Nd-143/Nd-144-1( 176)Hf/Hf-1(77) composition within error of chondrite meteorites, which include the likely parent bodies of Earth. This supports a hypothesis where the source of kimberlites and ocean island basalts contains a long-lived component that formed by melt extraction from a domain with chondritic Nd-143/Nd-144 and Hf-176/Hf-177 shortly after Earth accretion. The geographic distribution of kimberlites containing the PREMA component suggests that these remnants of early Earth differentiation are located in large seismically anomalous regions corresponding to thermochemical piles above the core-mantle boundary. PREMA could have been stored in these structures for most of Earth's history, partially shielded from convective homogenization. ISSN:0027-8424 ISSN:1091-6490

Arsenic concentrations in groundwater extracted from quaternary alluvial sediments pose a serious health issue for inhabitants living in several countries in Southeast Asia. A widely approved hypothesis states that reductive dissolution of Fe-bearing minerals releases As oxyanions to ground water and the original source of As has to be located in mafic rocks occurring across the entire Himalayan belt. Yet, recent trace element analyses of ground water from the lowlands (Terai) of Nepal show a clear decoupling of As and Fe. The positive correlation of K, Na, and trace elements like Li, B, and Mo with arsenic points out to clay minerals hosting the toxic element. This pattern of trace elements found in the ground water of the Terai also advocates against an original source of As in mafic rocks. The lithophile elements like Li, B, P, Br, Sr, and U reflect trace element composition typical for felsic rocks as an origin of As. All the mentioned elements are components of clay minerals found ubiquitously in some of the most characteristic felsic rocks of the Nepal Himalaya: metapelites and leucogranites—all these rocks exhibiting a high abundance of especially B, P, and As besides Cd and Pb.

Widespread magmatic activity developed in the Middle Miocene in the Cappadocian Region of Central Anatolia in Turkey. Despite several previous studies that focus on the geochemical features of the magmatic rocks, the source components and development of melting conditions are still a matter of debate. Recent basaltic rocks from Karaburna and Gulsehir (1228 and 96 Ka, respectively, Dogan, 2011) are considered as a part of the Central Anatolian Volcanic Province, situated at the northernmost end of the Cappadocian Region. These lavas have similar large ion lithophile (LIL) (except Rb) and high field strength (HFS) element abundances, however, Karaburna samples are more enriched in HFS elements, and both of the rocks suites reflect HFS depletions relative to the OIB signature. Karaburna and Gulsehir basalts have low Nb/La (0.45–0.5; 0.35–0.5), Nb/Th (2.75–4.61; 1.26–2.85) values, respectively, suggesting contributions from crustal sources, whereas Zr/Ba ratios of these samples range between 0.32–0.93 and 0.4–0.88 and imply that these rocks appear to be derived from asthenospheric sources. These incompatible element ratios can be attributed to either different geochemical processes, or are related to melting from different source component(s). The ambient mantle source of the Cappadocian region appears to be consistent with spinel peridotite, but this domain is not solely satisfactory to represent the melting conditions in the light of new elemental data. Values of Tb/Yb(N) and Zn/Fe provide new constraints suggesting the magmas were generated from the asthenosphere. Tb/Yb(N) ratio separates garnet – spinel transition Tb/Yb(N) (>1.8) and Zn/Fe ratio displays separation between the peridotite-derived (Zn/Fe A melting model based on REE ratios and Zn/Fe, Co/Fe, Tb/Yb(N) values indicate that basaltic rocks were not derived from a single source component (peridotite). Instead, those values suggest substantial melting contributions from a pyroxenite source domain, which has not been discussed as a source component in previous studies. Melts, from both of the source domains, with the result of asthenospheric upwelling linked to the downgoing Aegean and Cyprean slabs, are distinct from the alkaline character frequently observed as the final products of recent volcanic activity in the Cappadocian region and also explains the different trace element variations observed in such a small scale.

International audience; Rhenium-Os, Ptsingle bondOs, Smsingle bondNd, Lusingle bondHf, and Hfsingle bondW isotope data, together with lithophile trace element and highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundances, are reported for 2.05 Ga Jeesiörova and Kevitsa komatiites from the Central Lapland Greenstone Belt, Fennoscandia, Finland. Both komatiites are closely genetically related, with the Kevitsa dikes having served as feeding magma conduits to the Jeesiörova pillowed and massive lavas. The parental komatiite magma is estimated to have contained ~25 wt% MgO and was, thus, derived from a mantle source at least as hot as those of some of its late Archean counterparts. A suite of Jeesiörova and Kevitsa whole-rock komatiite samples and olivine and chromite separates define an internal Resingle bondOs isochron with an age of 2049 ± 13 Ma and an initial γ187Os = −0.2 ± 0.2 (2SE), indicating long-term chondritic Re/Os in the mantle source. By contrast, Ptsingle bondOs data for a set of Jeesiörova chromite separates define an average initial μ186Os = +29 ± 2 (2SE), indicating a long-term history of suprachondritic Pt/Os in the mantle source. The absolute HSE abundances in the mantle source of the Jeesiörova-Kevitsa komatiite system are estimated to have been 120 ± 5% of the present-day Bulk Silicate Earth (BSE). This is the first komatiite system for which excess HSE in the mantle source, relative to modern BSE, has been documented.The 147Smsingle bond143Nd and 176Lusingle bond176Hf data yield isochron ages and initial ratios of, respectively, 2046 ± 22 Ma with ε143Nd = +3.7 ± 0.3, and 2072 ± 20 Ma with ε176Hf = +8.7 ± 0.4 (2SE), indicating a long-term history of depletions of Nd relative to Sm, and Hf relative to Lu. The measured μ182W = +1.5 ± 3.3 is indistinguishable from the modern mantle value. Despite being strongly depleted in highly incompatible lithophile trace elements, the Th-Nb-La systematics of the komatiites indicate ~1% crustal contamination of the original komatiite magma, assuming the contaminant was similar in composition to the calculated Fennoscandian Tonalite Average (FTA). This level of contamination would have also significantly modified the Nd, Hf, and W isotope compositions of the original komatiitic magma, but not the Os isotope compositions or HSE abundances. The calculated original komatiite magma, corrected for the effects of crustal contamination, would have had initial ε143Nd ~ +4.9, ε176Hf ~ +10.2, and μ182W ~ −10.Our modeling indicates that the initial 186,187Os/188Os isotopic compositions and suprachondritic HSE abundances, coupled with the projected negative μ182W, are best explained by either (1) derivation from a mantle domain characterized by an excess of late accreted, differentiated planetesimal core metal, i.e., “grainy” late accretion, or (2) addition of chemically fractionated terrestrial core metal to the mantle source domain of the komatiites. The presence of these characteristics in the Jeesiörova-Kevitsa komatiite mantle source provides further evidence for the early creation and long-term survival of chemically diverse domains within the mantle.

Early Paleozoic tectonic evolution of Qinling Orogenic Belt and Shangdan Ocean remains an argument because of the different understandings of Early Paleozoic geological records, including the petrogenesis of magmatic and metamorphic rocks and formation setting of Liuling Groups. In this paper, we present zircon U–Pb data and geochemical and isotopic compositions of the lamprophyres in the southern part of North Qinling Orogenic Belt. The lamprophyres yield zircon U–Pb ages of ca. 470 Ma and are coeval with the Early Paleozoic potassium–rich mafic rocks (Fushui complex). The lamprophyres belong to calc-alkaline series and are characterized by enrichment in large-ion lithophile elements and light rare earth elements and depletion in high field strength elements. Lamprophyre and mafic rocks, etc, the crust-like geochemical signatures represent a source feature. The lamprophyres also have high initial Sr ratios of 0.706859 to 0.713288 and enrich Nd isotopic composition with eNd(t) values of − 6.8 to − 8.3, implying that they are derived from the enriched subcontinental lithospheric mantle. In addition, the lamprophyres intrude into the supracrustal Luohansi Formation, representing their shallow intrusive level, and cross through the crust and carry the key information. In the lamprophyres, there are many Neoproterozoic zircon xenocrysts with ages of 813.3 to 825.6 Ma, which is affinity with South Qinling Orogenic Belt. This is an implication of the closure of Shangdan Ocean and collision between North Qinling Orogenic Belt and South Qinling Orogenic Belt during the formation of lamprophyre.