Fractionation Trends Research Articles

High-Density Upper Amphibolite/Granulite Facies Fluid Inclusions in Magmatic Garnet from the Koralpe Mountains (Eastern Alps, Austria)

Fluid and solid inclusions in magmatic garnet from Permian pegmatites of the Koralpe Mountains were investigated. On the basis of MnO/(MnO + FeO) ratios, different degrees of melt fractionation during garnet growth were linked with fluid inclusion densities and chemistries. It is shown that garnet indicating low-melt fractionation trends contained primary CO2 ± N2-rich fluid inclusions of the highest densities, up to 1.15 g/cm3, compared to garnet samples of increased fractionation trends comprising CO2-N2-rich fluid inclusions with lower densities up to 0.85 g/cm3. This fluid composition is interpreted as a part of an unmixed CO2 ± N2-H2O-rich fluid that was present during garnet crystallization. Variabilities in the nitrogen composition up to 40.83 mol% resulted from different degrees of partial melting of mica and plagioclase from the metapelitic host rock. Densities, fluid chemistries, and mineral chemical data enabled a continuous upward trend for garnet crystallization during anatexis from lower (ca. 25 km) up to middle crustal levels (12–15 km). Resulting amphibolite/granulite facies conditions of 7.6 kbar/700 °C for garnet crystallization in spodumene-free pegmatites were significantly higher than previously suggested for pegmatite formation in the Koralpe Mountains.

Temporality of body mass index, blood tests, comorbidities and medication use as early markers for pancreatic ductal adenocarcinoma (PDAC): a nested case–control study

ObjectivePrior studies identified clinical factors associated with increased risk of pancreatic ductal adenocarcinoma (PDAC). However, little is known regarding their time-varying nature, which could inform earlier diagnosis. This study assessed...

Extinguishing the FIRE: environmental quenching of satellite galaxies around Milky Way-mass hosts in simulations

ABSTRACT The star formation and gas content of satellite galaxies around the Milky Way (MW) and Andromeda (M31) are depleted relative to more isolated galaxies in the Local Group (LG) at fixed stellar mass. We explore the environmental regulation of gas content and quenching of star formation in z = 0 galaxies at $M_{*}=10^{5\!-\!10}\, \rm {M}_{\odot }$ around 14 MW-mass hosts from the Feedback In Realistic Environments 2 (FIRE-2) simulations. Lower mass satellites ($M_{*}\lesssim 10^7\, \rm {M}_{\odot }$) are mostly quiescent and higher mass satellites ($M_{*}\gtrsim 10^8\, \rm {M}_{\odot }$) are mostly star forming, with intermediate-mass satellites ($M_{*}\approx 10^{7\!-\!8}\, \rm {M}_{\odot }$) split roughly equally between quiescent and star forming. Hosts with more gas in their circumgalactic medium have a higher quiescent fraction of massive satellites ($M_{*}=10^{8\!-\!9}\, \rm {M}_{\odot }$). We find no significant dependence on isolated versus paired (LG-like) host environments, and the quiescent fractions of satellites around MW-mass and Large Magellanic Cloud (LMC)-mass hosts from the FIRE-2 simulations are remarkably similar. Environmental effects that lead to quenching can also occur as pre-processing in low-mass groups prior to MW infall. Lower mass satellites typically quenched before MW infall as central galaxies or rapidly during infall into a low-mass group or a MW-mass galaxy. Most intermediate- to high-mass quiescent satellites have experienced ≥1–2 pericentre passages (≈2.5–5 Gyr) within a MW-mass halo. Most galaxies with $M_{*}\gtrsim 10^{6.5}\, \rm {M}_{\odot }$ did not quench before falling into a host, indicating a possible upper mass limit for isolated quenching. The simulations reproduce the average trend in the LG quiescent fraction across the full range of satellite stellar masses. Though the simulations are consistent with the Satellites Around Galactic Analogs (SAGA) survey’s quiescent fraction at $M_{*}\gtrsim 10^8\, \rm {M}_{\odot }$, they do not generally reproduce SAGA’s turnover at lower masses.

Siderophile volatile element inventory in lunar magmatic rocks and mantle sources

Elevated water contents in various lunar materials have invigorated the discussion on the volatile content of the lunar interior and on the extent to which the volatile element inventory of lunar magmatic rocks is controlled by volatility and degassing. Abundances of moderately volatile and siderophile elements can reveal insights into lunar processes such as core formation, late accretion and volatile depletion. However, previous assessments relied on incomplete data sets and data of variable quality. Here we report mass fractions of the siderophile volatile elements Cu, Se, Ag, S, Te, Cd, In, and Tl in lunar magmatic rocks, analyzed by state-of-the-art isotope dilution-inductively coupled plasma mass spectrometry. The new data enable us to disentangle distribution processes during the formation of different magmatic rock suites and to constrain mantle source compositions. Mass fractions of Cu, S, and Se in mare basalts and magnesian suite norites clearly correlate with indicators of fractional crystallization. Similar mass fractions and fractional crystallization trends in mafic volcanic and plutonic rocks indicate that the latter elements are less prone to degassing during magma ascent and effusion than proposed previously. The latter processes predominate only for specific elements (e.g., Tl, Cd) and complementary enrichments of these elements also occur in some brecciated highland rocks. A detailed comparison of elements with different affinities to metal or sulfide and gas phase reveals systematic differences between lunar magmatic rock suites. The latter observation suggests a predominant control of the variations of S, Se, Cu, and Ag by mantle source composition instead of late-stage magmatic degassing. New estimates of mantle source compositions of two low-Ti mare basalt suites support the notion of a lunar mantle that is strongly depleted in siderophile volatile elements compared to the terrestrial mantle.

Multi-stage construction of the Little Cotton wood stock, Utah, USA: Origin, intrusion, venting, mineralization, and mass movement

AbstractMany porphyry molybdenum deposits are hosted in multi-phase plutons, but it is unclear in some deposits how these magmas originated and whether the pluton intruded as it fractionated or was intruded by new batches of magma. New mapping has clarified field relationships between units in the White Pine porphyry Mo system hosted in the Little Cottonwood stock, Utah (western United States), including the White Pine intrusion, the Red Pine porphyry, rhyolite dikes, and phreatomagmatic pebble dikes. Geologic relations and geochemistry show the system formed in a continental arc setting during rollback of the subducting Farallon slab rather than during extension related to orogenic collapse. Whole-rock geochemistry shows distinct fractionation trends for each of the major intrusive units in the composite pluton, suggesting they formed separately, which is supported by new U-Pb zircon laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) ages of ca. 30 Ma for the Little Cottonwood stock, 27 Ma for the White Pine intrusion, and 26 Ma for the previously undated Red Pine porphyry. Mineral textures, cross-cutting relationships, and alteration mineralogy indicate that intrusion of the youngest phase led to a fluid-saturated magmatic system and triggered venting, including emplacement of pebble dikes. In the adjacent east Traverse Mountains, pebble dikes contain clasts that have similar mineral assemblages, textures, and ages as the major igneous units in the White Pine deposit. This indicates that the pebble dikes in east Traverse Mountains and in the pluton are the upper and lower parts of the same magmatic-hydrothermal system, which was decapitated by a mega-landslide that was likely facilitated by alteration in the Oligocene hydrothermal system and by later Basin and Range faulting.

Geochemistry of granitoids from the Austroalpine Seckau Complex: a key for revealing the pre-Alpine evolution of the Eastern Alps

Recent studies revealed that the calc-alkaline metagranitoids of the Seckau Complex comprise both (1) a Late Cambrian to Early Ordovician and (2) a Late Devonian to Early Carboniferous (early Variscan) intrusive complex. The older rocks of the Hochreichart Plutonic Suite reflect I to S-type affinity and are peraluminous and characterized by a general decrease in TiO2, Al2O3, MgO, CaO, P2O5, FeOt and MnO with increasing SiO2. Chondrite-normalized rare earth element (REE) plots display a slight enrichment in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) as well as negative Eu anomalies ((Eu/Eu*)N = 0.15- 0.77). The whole-rock initial 87Sr/86Sr ratios calculated back to the time of emplacement (~ 496 Ma) vary between 0.7056 to 0.7061. The early Variscan rocks of the Hintertal Plutonic Suite can be subdivided into (a) the meta- to peraluminous granodioritic suite of the Pletzen Pluton and (b) the peraluminous granitic suite of the Griessstein Pluton. The Pletzen Pluton shows typical magmatic fractionation trends for most of the major oxides and trace elements plotted against SiO2. On a chondrite-normalized diagram, metagranitoids are strongly enriched in LREE and show no significant negative Eu anomaly. Metagranitoids of the Griessstein Pluton have a more peraluminous character and similar major and trace element fractionation trends compared to the Pletzen Pluton. However, the contents in SiO2, major and trace elements clearly point towards a more evolved melt with generally lower TiO2, Al2O3, MgO and CaO values and higher K2O content. Metagranitoids of the Griessstein Pluton are additionally characterized by a slight negative Eu anomaly of about 0.81 on a chondrite-normalized REE plot. Initial 87Sr/86Sr values calculated back to the time of emplacement (~ 353 Ma) of the Pletzen Pluton and the Griessstein Pluton vary between 0.7051—0.7061 and 0.7054—0.7063, respectively, and suggest the same magmatic source for both units. Application of rhyolite-MELTS modelling to the Hintertal Plutonic Suite revealed that the Griessstein Pluton formed by fractional crystallization (~ 30%) from the more primitive Pletzen Pluton. Our geochemical data from the Hochreichart Suite granitoids suggest the existence of a Late Cambrian to Early Ordovician active margin with its remnants now exposed in the Seckau Complex. The early Variscan grainitoids of the Seckau Complex are inferred as part of a magmatic arc along the southern Bohemian active continental margin that was related to the subduction of differently termed oceanic domains (Galicia-Moldanubian Ocean or Paleotethys), prior to the final collision of Gondwana and Laurussia. The general paleogeographic position of the Seckau Complex during the Variscan orogeny is considered to be south to southeast of the Bohemian Massif, adjacent to the eastern Hohe Tauern, the Schladming Tauern, and the Western Carpathians.

Gadolinium-dominant monazite and xenotime: Selective hydrothermal enrichment of middle REE during low-temperature alteration of uraninite, brannerite, and fluorapatite (the Zimná Voda REE-U-Au quartz vein, Western Carpathians, Slovakia)

AbstractA hydrothermal quartz vein with REE-U-Au mineralization in the Zimná Voda (Gemeric Unit, Western Carpathians, Slovakia) is associated with contact metamorphism between Permian granites and host phyllites and metaquartzites. It contains unique REE minerals of the monazite and xenotime groups. Monazite-(Ce), monazite-(Nd), monazite-(Sm), and Gd-dominant monazite [“monazite-(Gd)”], along with xenotime-(Y) to Gd-dominant xenotime [“xenotime-(Gd)”] and Gd-rich hingganite-(Y) show heterogeneous compositions and reflect a strong fractionation trend toward the enrichment of MREE (Sm to Dy), particularly Gd. Here, the gadolinium abundance reported in “monazite-(Gd)” (≤23.4 wt% Gd2O3) and Gd-rich xenotime-(Y) to “xenotime-(Gd)” (≤28.7 wt% Gd2O3) and accompanied by Gd-rich hingganite-(Y) (≤15.8 wt% Gd2O3), is among the highest Gd concentrations ever reported in natural minerals. The Gd-richest compositions show the following formulas: (Gd0.31Sm0.24 Nd0.15Ce0.10La0.05Dy0.03Y0.03…)0.98PO4 [“monazite-(Gd)”], (Gd0.36Y0.32Dy0.13Sm0.08Tb0.05…)0.98 (P0.96As0.04)1.00O4 [“xenotime-(Gd)”] and (Y0.71Gd0.43Dy0.23Sm0.22Tb0.06Er0.04Nd0.06…Ca0.06)1.96 (☐0.87Fe0.132+)1.00(Be1.82B0.18)2.00(Si1.90As0.10)2.00O8(OH1.70O0.30)2.00 [hingganite-(Y)]. The MREE-rich monazites, xenotimes, and hingganite-(Y) precipitated in response to the alteration of primary uraninite, brannerite, and fluorapatite by low-temperature hydrothermal fluids of heterogeneous compositions on a microscale. These are responsible for the strong enrichment of individual MREE, especially Gd in the secondary minerals. This is accompanied by the advancing development of the W-type tetrad effect on REE through monazite species. The substantial incorporation of Gd into both REE-selective monazite and xenotime structures that are accompanied by LREE vs. HREE segregation indicates the possibility of differently sized REE3+ miscibility in REEPO4 solid solutions, as well as the stabilization of the Gd-rich orthophosphate structure by substitution of the remaining A-site cations with smaller HREE+Y in the xenotime-type, and/or larger LREE in the monazite-type structure.

Fractional mega trend diffusion function-based feature extraction for plant disease prediction

Fractional mega trend diffusion function-based feature extraction for plant disease prediction

Petrogenesis and redox state of late Mesozoic granites in the Pingmiao deposit: Implications for the W–Cu–Mo mineralization in the Dahutang district

The Pingmiao W (Cu) deposit is located in the central part of the newly-discovered giant Dahutang ore-concentrated district, South China. Field relationships and mineral assemblages confirm that the W (Cu) mineralization in the Pingmiao deposit is genetically related to multiphase late Mesozoic granites, which include the porphyritic two-mica granite, biotite granite porphyry, fine-grained muscovite granite, and Li-mica albite granite. Zircon U–Pb dating shows that these granites emplaced at ca. 146–143 Ma, which are coeval with the W–Cu–Mo-bearing granitoids from other ore deposits in the Dahutang district. The strongly peraluminous (A/CNK > 1.1) feature, negative correlations between Rb and Th and between Rb and P2O5, low Zr + Nb + Ce + Y values (mostly lower than 200), and relatively low Zr saturation temperatures (lower than 800 °C) suggest that these granites are typical S-type granite. These granites show similar Nd isotopes (−8.91 to −4.61), CaO/Na2O (0.2–0.57), and Al2O3/TiO2 (mostly ranging of 50–90) ratios with those W–Cu–Mo-bearing granitoids from other ore deposits in the Dahutang district, suggesting that they derived from partial melting of metapelites in the Shuangqiaoshan Group (or the Proterozoic metamorphic basement geochemically similar to the Shuangqiaoshan Group), with involving of minor mafic–ultramafic volcanic rocks. Geochemical fractionation trends recorded by whole-rocks and micas permit to distinguish the evolutionary trend from the porphyritic two-mica granite and biotite granite porphyry to the fine-grained muscovite granite and Li-mica albite granite. The apparent rare earth element tetrad effect, high Li and F contents, low K/Rb, Zr/Hf, and Nb/Ta ratios, as well as the zoned features of micas suggest that the melt–fluid interaction occurring during the formation of Li-mica albite granite. The Pingmiao granites have reduced redox state, revealed by their low whole-rock Fe2O3/FeO ratios (mostly <0.5), biotite Fe3+/Fe2+ ratios (ranging of 0.02–0.07), zircon Ce4+/Ce3+ ratios (median value of 18.70), and oxygen fugacity (near or below the FMQ buffer). The data in this study indicate that the late Mesozoic granitoids in the Dahutang district are favorable for W, Cu (<1 Mt), and Mo (<0.3 Mt) mineralization. Notably, the more evolved Li-mica albite granite has potential for W, Sn, Nb and Ta mineralization.

LA‐ICP‐MS analysis of rare earth elements in tooth enamel of fossil small mammals (Ust‐Oda section, Fore‐Baikal area, Siberia): paleoenvironmental interpretation

ABSTRACTThis paper presents the results of a study of rare earth element (REE) fractionation trends in Quaternary mammal remains with the aim to test stratigraphic provenance. The primary aim was to find a solution to the problem of the formation of small mammal disharmonious associations, which is closely connected to the problem of diagnostics of redeposited paleontological material. REE were analyzed from the tooth enamel of small mammal fossils and sediments collected from five stratigraphic units (Ust‐Oda section of Upper Pleistocene terrestrial sediments, Fore‐Baikal area, Siberia). The Ust‐Oda is currently the only known section in the region where a fixed stratigraphic sequence of the Late Pleistocene to Holocene marine isotopic stages (MIS 5–1) occurs. The results for REE signatures of tooth enamel enable us to draw conclusions regarding changes in physical and chemical environmental conditions during diagenesis and afford the possibility of applying geochemical factors signifying REE fractionation to sample classification. This, in turn, allowed us to establish that some small mammal remains found in sediments belonging to the Ust‐Oda section have been redeposited.

Two magma fractionation paths for continental crust growth: Insights from the adakite-like and normal-arc granites in the Ailaoshan fold belt (SW Yunnan, China)

Abstract Geochemical similarities between the continental crust and arc magmas have led to the inference that subduction zones may be the primary sites of crustal growth. Thus, it is necessary to unravel the petrogenetic mechanism(s) of granitoid generation in subduction-related settings to understand crustal growth through magmatic differentiation processes. In this study, we focused on granitoid generation in oceanic-continental subduction zones. We analyzed the whole-rock geochemistry and Sr-Nd isotopes, together with zircon U-Pb-Hf-O isotopes, of the newly identified Middle Triassic granitoids in the Ailaoshan high-grade metamorphic complex (Yunnan, SW China). All the studied granite samples were characterized by large ion lithophile element (e.g., Rb, Sr, and Ba) enrichments and high field strength element (e.g., Nb, Ta, and Ti) depletions, similar to arc-type rocks. They also showed a range of whole-rock Sr-Nd, (87Sr/86Sr)i = 0.7020–0.7048, εNd(t) = +0.6 to +4.2, and zircon Hf-O, εHf(t) = +10.3 to +18.1, δ18Ozircon = 5.09‰–6.65‰, isotope compositions, which overlap with those of previously reported coeval (ca. 237–235 Ma) hornblende diorite and granodiorite, the formation of which was interpreted to have originated from a mantle wedge metasomatized by a sediment-derived melt. Furthermore, the fractionation trends of some of the granitic samples and diorite-granodiorite suite overlap. They can be divided into two geochemical groups: Group 1 has intermediate to high SiO2 (66.9–73.8 wt%) and K2O (3.40–5.42 wt%) and low MgO (0.19–1.09 wt%) contents and shows depletion in heavy rare earth elements (HREEs; e.g., Yb and Y), resulting in adakite-like high Sr/Y (61–183) and La/Yb (47–90) ratios. Group 1 shows positive SiO2 versus Sr/Y and La/Yb correlations and negative SiO2 versus HREE and Y correlations, implying fractionation of a garnet-bearing assemblage. The negative correlations between SiO2 and εNd(t) and Nb/La reveal a crustal assimilation trend. Group 2 has relatively high SiO2 (72.6–76.5 wt%) and low K2O (1.93–3.82 wt%) and MgO (0.05–0.83 wt%) contents and shows depletion in middle REEs (MREEs; e.g., Gd and Dy) with low Sr/Y (1–10) and La/Yb (4–11) ratios. Group 2 granites show negative Gd/Yb versus SiO2 correlation, which indicates significant fractionation of an amphibole-bearing assemblage. Our results suggest that both group 1 and 2 granites were formed in a subduction setting from a common mantle-derived parental dioritic magma, but they experienced two distinct fractionation processes. While group 1 granites were likely formed by crustal assimilation and high-pressure (lower-crustal) garnet-dominated fractionation, group 2 granites were generated through low-pressure (middle-/upper-crustal) amphibole-/plagioclase-dominated fractionation. We suggest that these two fractionation trends are critical to crustal growth and the development of a more fractionated (felsic) upper crust.

Basalt Chronology of the Orientale Basin Based on CE-2 CCD Imaging and Implications for Lunar Basin Volcanism

The specific duration between the impact event and subsequent volcanic flows is highly variable based on previous works. The method of crater size-frequency distribution (CSFD) has been previously used to date the basalt in Orientale Basin, which yielded inconsistent resultant Absolute Model Age (AMA) ranges. The inconsistency may be attributed to the choice of counting area and identified superposed craters. In this study, we integrated the Chang’E-2 (CE-2) imaging data (7 m/pix) and the IIM and 20 m CE-2 DTMS data, re-divided Mare Orientale, and re-estimated the age of the basalts there. The ages revealed that (1) the central basalts had multiphase eruptions, beginning at 3.77 Ga (30 My after the impact event) with the longest duration of 1.51 Gy; (2) the edge basalts have a similar features as the central basalts, beginning at 3.75–3.50 Ga (50–300 My after the impact) with the longest duration of 0.67 Gy. Compared with the basalts along the basinal margin, the central basalts have higher Ti but lower Mg# contents, consistent with the basaltic magma fractionation trend. Spatial distribution characteristics indicate that the basalt eruption occurred in the impact direction upstream and in the center, but almost absent in the impact direction downstream. Accordingly, we speculate that the longevity of the lunar mare basaltic volcanism was affected by gravity changes, material balance, and other post-impact processes.

Basaltic volcanism of Medvezhia caldera on the Iturup Island of Kurile Isles: impact of regional tectonics on subduction magmatismMartynov Yu.А., Rybin А.V., Chibisova М.V., Ostapenko D.S.,Davydova M.Yu

ABSTRACT We present newly acquired data on the trace element composition and Sr–Nd–Pb-O isotopes of Pliocene – Holocene basalts of the Medvezhiy caldera located on the Iturup Island, Kuril arc. With its unique rhenium mineralization and high-Mg basalt volcanism, it is the largest caldera on the volcanic front of the Kurile Island arc. The calc-alkaline suite of rocks spanning the range from high-Mg basalts to high-Al basalts, has typical arc rock features, such as Nb-Ta depletion and LILE enrichment. The whole set of the caldera geochemical data is divided into two age units, pre- and postcaldera basalts. The precaldera basalts typify low-K, high-Al, basaltic suite of the frontal zones of «cold» subduction. PRIMACALC2 code and Arc Basalt Simulator version 3.1 forward model points to ~21.7% of partial melting of moderately depleted mantle peridotite with relatively high water content (~0.34 wt%) at the pressure of ~1.37 GPa. With similar isotope and trace element signatures, Late Pleistocene–Holocene basalts are marked by the high abundances of MgO (up to 11 wt %), but low Al2O3. The primary magmas were generated from depleted mantle with lower H2O content (~0.13%) and degree of partial melting (~9.5%), but at higher pressure (~1.77 GPa). The decompression scheme reproduces the fractionation trends of postcaldera magnesian basalts for most major elements but fails to explain the composition variations of the precaldera lavas. Their origin has been the matter of some complex processes in the shallow magma chamber. The abrupt change in the type of eruptions and magma composition of the caldera in Late Pleistocene–Holocene were related to a transformation of both the magma-feeding and melt generation systems as the result of geodynamic reorganization of the vast territory adjacent to the Sea of Japan and Kamchatka.

Effect of Hot Working Parameters on Microstructure and Texture Evolution of Hot-Deformed Zr-45Ti-5Al-3V Alloy.

The effect of hot working parameters on the microstructure and texture evolution of the hot-deformed Zr-45Ti-5Al-3V alloy was studied by the electron backscatter diffraction (EBSD) technique. It was found that a high density of dislocations were generated when the alloy was deformed at 700 °C/0.001 s−1 and 800 °C/1 s−1. With the increment in hot-deformation temperature and the decrease in strain rate, the dislocation density decreased due to the increase in dynamic recrystallization (DRX) degree. The discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) mechanisms co-existed during the hot working of the Zr-45Ti-5Al-3V alloy at a true strain of 0.7. The texture evolution of the alloy during hot working was characterized and the texture component mainly consisted of {001}<100>, {011}<100>, {110}<112>, and {112}<110> textures. The volume fractions of {001}<100> and {011}<100> textures obviously rose with the reduction in strain rate, whereas those of {110}<112> and {112}<110> textures gradually decreased. At a given strain rate, an increase trend in the volume fraction of the {001}<100> texture was observed with rising hot-deformation temperature, while the volume fraction of the {011}<100> texture first increased and then decreased. An opposite trend was visible in the {112}<110> and {110}<112> texture compared with {011}<100> textures.

Chemical study of group IIIF iron meteorites and the potentially related pallasites Zinder and Northwest Africa 1911

Group IIIF was established as a magmatic iron-meteorite group based on similar Ga and Ge abundances, unusually high Ga/Ge ratios, and the IIIAB-like interelement trends in its members; recent Mo and Ru isotopic data indicate that three of its members exhibit the isotopic signature of carbonaceous-chondrite (CC) irons. Here we report the elemental chemistry of this group and model its crystallization history. Included are new elemental data for IIIF irons acquired by both instrumental neutron activation analysis (INAA) and laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). A fractional-crystallization model was used to evaluate the IIIF compositional trends for 19 elements and was unable to explain the observed fractionation trends for several key elements (Co, Ga, Ge). In particular, the inability of this model to match Co in the IIIF irons is striking because (1) group IIIF has the widest Co variation among all magmatic iron groups and (2) none of the tested initial S contents (0–20 wt.%) explains both the wide Co variation and steep Co-As slope. Attempts to fit subsets of the IIIF irons were also unsuccessful. In addition, group IIIF has the greatest variety of structural classes and kamacite bandwidths among all established magmatic iron groups. If the IIIF irons constitute a coherent group, they were derived from a parent body that experienced more complex processes than simple fractional crystallization of the core.The Zinder and Northwest Africa (NWA) 1911 pyroxene-bearing pallasites were recently suggested to be related to group IIIF based on their Ga and Ge contents, and we completed a petrographic study of the pallasite silicates and LA-ICP-MS analyses of their metal fractions. The two pallasites are related to one another: they have nearly identical mineralogical, elemental and O-isotopic compositions in their silicates and metals. Their metallic compositions resemble those of the IIIF irons Moonbi, St. Genevieve County, and Cerro del Inca, but their O-isotopic compositions resemble those of non-carbonaceous (NC) achondrites. Additional isotopic measurements are needed to test the potential genetic relationship to group IIIF.

Crustal Contamination and Hybridization of an Embryonic Oceanic Crust during the Red Sea Rifting (Tihama Asir Igneous Complex, Saudi Arabia)

AbstractThe Red Sea rift system represents a key case study of the transition from a continental to an oceanic rift. The Red Sea rifting initiated in Late Oligocene to Early Miocene (24–23 Ma) and was accompanied by extensive magmatism throughout the rifted basin, from Afar and Yemen to northern Egypt. Here, we present a petrological and geochemical study of two gabbro bodies and associated basalts from the Tihama Asir igneous complex, which formed at 24–20 Ma within the rifted Arabian-Nubian Shield (ANS). The Tihama Asir is therefore an ideal location to study the initial phase of syn-rift magmatism and its influence on the geodynamic evolution of the Red Sea rift system. The most primitive olivine gabbros present modal, bulk and mineral compositions consistent with formation from Mid-Ocean Ridge Basalt (MORB)-type parental melts, whereas the evolved olivine-free gabbros and oxide-bearing gabbros show saturation of phlogopite and a crystal line of descent diverging from fractional crystallization trends. In detail, whole-rock and mineral compositions in the most evolved lithologies show high Light over Middle Rare Earth Elements (LREE/MREE) ratios (LaN/SmN = 0.89–1.31) and selective enrichments in Sr, K and highly incompatible elements (Rb, Ba, U, Th). We relate these geochemical characteristics to a process of progressive assimilation of host continental crust during the emplacement of the gabbroic plutons. Interestingly, high LREE/MREE ratios (LaN/SmN = 1.45–4.58) and high Rb, Ba, Th and U contents also characterize the basaltic dike swarms associated to the gabbros. Incompatible trace element compositions of these basalts approach those of the melts that formed the most hybridized gabbros. Therefore, we propose that the dike swarms represent melts partially contaminated by assimilation of continental crust material, extracted from the underlying gabbroic crystal mush. Our results suggest that early syn-rift magmatism led to the partial replacement of the thinned continental crust by MORB-type gabbroic bodies, in turn suggesting that oceanic magmatism started prior to continental break-up. Extensive syn-rift magmatism is consistent with the interpretation of the southern Red Sea rift system as a volcanic rifted margin. One possible implication of this study is that extensive but diffuse syn-rift magmatism possibly hampered continental break-up, leading to a protracted rifting stage.

Calcium and strontium stable isotopes reveal similar behaviors of essential Ca and nonessential Sr in stream food webs

AbstractRecent studies showed the potential of stable isotopes of the macronutrient calcium (δ44/40Ca) and nonessential strontium (δ88/86Sr) as new trophic level indicators in terrestrial vertebrates and marine teleost fishes. In this study, we tested whether similar Ca and Sr isotopic fractionation trends existed in macroinvertebrate‐dominated stream food webs compared to vertebrates despite their physiological differences. We have determined the δ44/40Ca and δ88/86Sr values as well as the 87Sr/86Sr ratios of stream macroinvertebrates and small gobies and their potential metal sources (stream water, periphyton, and terrestrial plant litter) in upper and lower reaches of two streams in the Lake Biwa catchment, central Japan. The 87Sr/86Sr ratios revealed that stonefly nymphs, crustacea, and gobies mostly relied on aquatic Sr sources. Higher 87Sr/86Sr ratios of some crane fly and caddisfly larvae, mayfly, dobsonfly, and dragonfly nymphs indicated greater terrestrial contributions via plant litter. Positive correlations between the δ44/40Ca and δ88/86Sr values implied that similar Ca and Sr sources existed, and that Ca and Sr stable isotopes underwent similar fractionation trends although Sr was not essential. The δ44/40Ca and partly the δ88/86Sr values were positively correlated with Sr/Ca ratios and negatively with δ15N values indicating trophic effects on Ca and Sr stable isotopes. The enrichment of 44Ca and 88Sr in large filter‐feeding caddisfly larvae was a notable exception from these trophic trends. Our data confirm that the trophic 44Ca and 88Sr depletion observed for marine teleost fishes and terrestrial vertebrates also applied to macroinvertebrate‐dominated stream food webs despite their different physiologies indicating that shared mechanisms of Ca and Sr isotopic fractionation may exist at the cellular or molecular level between these taxa.

Effects of Abrasive Rock Type on CVF-Dependent Performance Trends of White Cast Irons in the Inner Circumference Abrasion Test

Although the trends of abrasion performance versus carbide volume fraction (CVF) of white cast irons (WCIs) have been studied to some extent, there remain gaps in understanding of the factors controlling performance. This study addresses three knowledge gaps. Firstly, the influence of testing conditions, more closely reproducing ore chute service, has been determined using the inner circumference abrasion test (ICAT), which included different natural rock types. The benefit of WCI compared to steels was much greater in basalt than in granite or greywacke. Secondly, the current work shows monotonic behavior for granite and greywacke but performance reversal in basalt, demonstrating that the reversal is not due to “more severe” or “high stress” conditions. The literature variously shows monotonic, plateauing, or reversing CVF dependence but has not convincingly explained these behaviors. Thirdly, the Cr/C ratio (previously neglected) shows no effect in granite, but lower Cr/C gives poorer performance in basalt. The trends are explained by relative responses of the microconstituents to different minerals. Basalt abrades both steel and the WCI matrix but not M7C3, thus maximizing the benefit of WCI but creating roughened surfaces with protruding carbides. This promotes carbide fracture in hypereutectic alloys and, hence, the reversal. Harder minerals create less differential and hence less protrusion and no plateau.

The Karavansalija Mineralized Center at the Rogozna Mountains in SW Serbia: Magma Evolution and Time Relationship of Intrusive Events and Skarn Au ± Cu–Pb–Zn Mineralization

The Karavansalija Mineralized Center (KMC) with its Au–Cu skarn mineralization associated with the Rogozna Mountains magmatic suite in southwestern Serbia belongs to the Oligocene Serbo-Macedonian magmatic and metallogenic belt (SMM-MB). Samples from intrusive and volcanic rocks at the KMC show typical arc signatures of subduction-derived magmas through enrichment in large-ion lithophile elements (LILE) and depletion of high–field strength elements (HFSE). The magmas developed a high-K (calc-alkaline) fractionation trend and evolved toward shoshonitic compositions. Whole-rock trace element data suggest plagioclase-absent, high-pressure amphibole ± garnet fractionation that generates adakite-like hydrous magmas during evolution in lower crustal magma chambers. Zircon LA–ICP–MS and high-precision CA–ID–TIMS dating together with zircon trace elements and Hf isotope measurements were carried out in order to couple the geochronologic and geochemical evolution of the KMC. The results suggest that magmatism starts around 29.34 Ma with granitic to rhyodacitic subvolcanic intrusions followed by a more evolved magmatic intrusion that was emplaced into Cretaceous limestone, generating a widespread skarn alteration at ca. 28.96 Ma. After a period of quiescence of about 1.2 My, either another magma body evolved or the same upper crustal magma chamber was recharged and also likely partly reactivated older plutonic rocks as indicated by xenocrysts. The REE ratios shift from apatite, titanite ± amphibole-dominated fractionation of the older magmatic event to crystallization of allanite, efficiently depleting the LREE and Th/U in the younger upper crustal magma. After a lamproite-like melt was injected, the increased heat and fluid pressure led to the expulsion of a quartz-monzonite porphyritic stock at ca. 27.72 Ma, strongly interacting with the skarns and established a fertile hydrothermal system. Soon after a non-mineralized second pulse of some porphyry dykes cut the previous phenocryst-rich “crowded” porphyries and skarns at ca. 27.60 Ma, thus bracketing the maximum timespan of ore mineralization to about 112 ± 45 Ka. Increased contribution of a lamproite-like melt is inferred from the presence of phlogopite micro-phenocrysts, phlogopitization of biotite, and diopside clusters in the latest porphyry dykes. There is a trend of increased crustal assimilation from the oldest volcanic phase to the emplacement of the youngest porphyry dykes recorded by ɛ-Hf of the zircons. Oligocene occurrences of significant base metal mineralization within Serbia, northern Macedonia, and Greece, e.g., Crnac, Rudnik, Veliki Majdan, Stratoniu, or the Cu–Au porphyry at Buchim (northern Macedonia), are all associated with trachy-andesitic (quartz latitic) porphyry dykes, which originated through post-collisional tectonic settings or upper plate extension involving reworking of crustal arc-derived rocks and partial melting of the mantle wedge. This study demonstrates that on the basis of field relationships and the application of high-precision CA-ID-TIMS zircon age data, pulses of porphyry dykes of a 10ka age range can be distinguished, and the timing of mineralization can be parenthized.

Effectiveness of clinical pathway in subjects with heart failure: A real-world study from Italian health claims

&#x0D; Background: Several process-of-care indicators have been developed and implemented to improve the quality of heart failure (HF) patients care. The aim of this study is to assess the relationship between a set of recommendations for HF care with measurable clinical outcomes, also in terms of outcomes that could be avoided.&#x0D; Methods: A retrospective cohort study was carried out on subjects with at least one hospitalization with a primary diagnosis of HF in 2007. Data were retrieved from healthcare utilization databases of Lombardy region (Italy). Exposure to selected recommendations (periodic control of echocardiogram and use of blockers of the renin-angiotensin system and beta-blockers) was recorded. All cause mortality and hospitalization with primary diagnosis of HF were considered as outcomes. Multivariable Cox models and Poisson model were fitted to estimate the exposure-outcome association.&#x0D; Results: Among 8207 cases of HF, those who adhered to none, one or all recommendations during the first year after diagnosis were 11%, 60% and 30%, respectively. Compared to patients who adhered to no recommendation, a significant mortality risk reduction of 24% (95% CI 17-31%) and 44% (36 52%) were observed for those who adhered to one and all recommendations, respectively. A significant reduction in the rate of re-hospitalizations in subjects adhered to at least one recommendation was also observed. A decreased trend in Population Attributable Fraction for death cases according to follow-up time was observed.&#x0D; Conclusion: A strict control of patients with HF through regular clinical examinations must be considered as fundamental for the reduction of mortality and re-hospitalizations.&#x0D;