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Basaltic volcanism on the Moon produced low- and high-Ti mare basalt suites that are also distinct with respect to their iron, titanium, and magnesium isotopic compositions. Here, the equilibrium fractionation of Fe and Ti isotopes between ilmenite and melt was experimentally investigated in order to evaluate the role of ilmenite in generating the isotopic compositional variability among the lunar mare basalts. Ilmenite crystallization experiments were conducted using two bulk compositions: an ilmenite-saturated basaltic andesite and an ilmenite-saturated Apollo 14 black glass, and the Fe and Ti isotopic compositions of the experimental ilmenites and glass (quenched melt) were analyzed using solution MC-ICPMS after hand-picking. Additionally, Nuclear Resonant Inelastic X-ray Scattering (NRIXS) measurements on synthetic ilmenite were conducted and compared to previous NRIXS measurements on synthetic lunar glasses in order to derive temperature-dependent equilibrium ilmenite-melt Fe isotopic fractionations. Experimentally determined ilmenite-melt fractionations were then incorporated into a lunar magma ocean crystallization model that tracks the major element and isotopic compositional evolution of lunar magma ocean cumulates and residual liquid. There is good agreement between the Fe equilibrium isotopic fractionation measured by NRIXS and the laboratory equilibration experiments, and we find that the isotopic fractionation is sensitive to ilmenite compositional differences (0 vs. 10% Fe3+). Further, the light Ti isotopic composition of ilmenite relative to the melt (Δ 49 Ti = ilmenite-melt − 0.09 ± 0.03 ‰ at 1100 ∘C) is consistent with the higher coordination of Ti in ilmenite relative to melts and results of previous studies. The modeled Ti isotopic compositions for lunar magma ocean cumulates display Ti isotopic variability sufficient to explain the low- and high-Ti mare basalt sources. However, the difference in Fe isotopic composition between the low- and high-Ti mare basalts cannot be attributed solely to ilmenite fractionation. Instead, Fe isotopic fractionation by additional products of lunar magma ocean crystallization, such as clinopyroxene, is required to generate the inferred Fe and Mg isotopic variability in the lunar mantle. Alternatively, the Fe and Mg isotopic compositions of the lunar mare basalts may indicate Fe-Mg interdiffusion has occurred in the Ti-rich component of the mare basalt source regions via reaction between ilmenite cumulates and the olivine- and pyroxene-rich lunar mantle. [ABSTRACT FROM AUTHOR]

Titanium isotopes are a promising tracer for planetary differentiation processes. The application of this tracer is, however, currently hampered by the lack of a robust estimate for the chondritic reservoir. Here, we conducted an inter-comparison Ti isotope study of three laboratories with the aim of providing an accurate and precise estimate for the chondritic reservoir. While previous estimates may suffer from heterogeneities on the sampling scale, we chose ordinary chondrites to minimise uncertainties associated with the necessary corrections for nucleosynthetic isotope variations in chondrites, and to allow the analysis of sufficiently large sample sizes representative for bulk meteorites. Titanium isotope data reported by the different laboratories are in good agreement with each other. Ordinary chondrites of different subgroups (H, L, LL) and petrologic types (3–6) display identical Ti isotope compositions within uncertainties (average δ49Ti = +0.023 ± 0.009 ‰, 2SE, n = 20; permille deviation of 49Ti/47Ti from the OL-Ti standard). The average Ti isotope composition of ordinary chondrites is within 2SE identical to that of OIBs (+0.029 ± 0.005 ‰, 2SE, n = 52) and all pre 2.7 Ga mafic and komatiitic rocks (+0.019 ± 0.006 ‰, 2SE, n = 58), indicating that the δ49Ti values of the bulk silicate Earth and ordinary chondrites are indistinguishable. Furthermore, our average Ti isotope composition of ordinary chondrites overlaps with those of the Moon, Mars and Vesta, suggesting a homogeneous inner Solar System in terms of mass-dependent Ti isotopes. [ABSTRACT FROM AUTHOR]

Titanium and Fe isotopic compositions of lavas from a calc-alkaline differentiation suite and corresponding mineral separates from the Rindjani Volcano, Indonesia show that Fe and Ti isotopic fractionations between minerals and melts are lower than those recorded in other suites at all stages of differentiation. The limited isotopic fractionation for Ti is likely due to low-Ti magnetite and clinopyroxene being the dominant carriers of Ti in Rindjani lavas, as these minerals are thought to have limited equilibrium Ti isotopic fractionation relative to silicate magmas. Other magmatic differentiation suites controlled by removal of Ti-rich magnetite and characterized by a lesser role of clinopyroxene have larger Ti isotopic fractionations. This effect is an indirect consequence of the elevated Fe3+/Fe2+ ratio of calc-alkaline magmas such as Rindjani, which promotes Fe3+ incorporation into magnetite at the expense of Fe2+-Ti4+ pairs, such that increased oxygen fugacity will subdue Ti isotopic fractionation in global magmatic series. Similarly, we find negligible Fe isotopic fractionation in Rindjani bulk rocks and mineral separates, unlike previous studies. This is also likely due to the oxidized nature of the Rindjani differentiation suite, which leads to similar Fe3+/Fe2+ ratios in melt and minerals and decreases overall mineral-melt Fe fractionation factors. Paired Ti and Fe isotopic analyses may therefore represent a powerful tool to assess oxygen fugacity during differentiation, independent from Fe 3+ determinations of erupted samples. [ABSTRACT FROM AUTHOR]

Stable Ti isotopes have been applied in the detrital sediment record to reconstruct the bulk composition of Earth's continental crust due to the relationship between magmatic differentiation and Ti isotopic compositions. However, no study has systematically evaluated the influence of provenance, physical, and chemical weathering on the composition of sediments relative to the protolith they originated from. To test the influence of these processes on Ti isotopic compositions we investigate the Ti isotope composition of 82 surface samples including loess, volcaniclastic rocks, river sediment, and two separate weathering profiles through igneous rocks, collected from a broad geographical area and a range of environmental conditions. Limited but significant Ti isotope fractionation exists in samples subjected to extreme chemical weathering processes, potentially as a result of elemental mobilization. For example, the δ49Ti isotopic composition of bauxites developed on Columbia River basalt varies by up to 0.1‰, becoming isotopically heavier with increasing weathering intensity. However, negligible variation in δ49Ti was found in a second profile of saprolites developed on weathered diabase. Titanium isotope variations in loess do not correlate with chemical weathering intensity or size sorting, but may instead be related to the provenance of the sediment. We find that the δ49Ti of Amazon River sediments is correlated with the Al/Zr ratio, indicating that δ49Ti is impacted by sediment sorting. At our study sites, the river averaged offset between the isotopic composition of the bedload and the suspended sediment fraction is 0.051‰, with the largest offset being + 0.116‰. Our data suggest that during chemical weathering, heavy Ti isotopes are preferentially incorporated into secondary minerals producing higher δ49Ti in intensely weathered soils. During fluvial transport, the Ti isotopic composition of fine-grained sediment is heavier than that of its coarser counterpart. Crustal protolith composition and sorting during transport and sedimentation have a stronger effect on the Ti isotopic composition than chemical weathering. Our results have implications for studies that utilize the Ti elemental concentration to calculate relative enrichment or depletion during chemical weathering and physical transport processes in the Critical Zone and for studies using Ti isotopes in terrigenous sediments to infer the composition of their provenance. [ABSTRACT FROM AUTHOR]

Titanium isotopes are a promising novel tracer for magmatic processes. The Ti isotope composition of the Earth's mantle is key for using this tracer on a planetary scale, however, recent studies point to potential Ti isotope variations in mantle rocks. This study presents stable Ti isotope data for well-characterised peridotites from the Horoman massif (Japan) as well as for primitive, orogenic (Variscan and Alpine belts) and South African ultrapotassic rocks. The peridotites originate from a continuous section across the layered Horoman peridotite body and comprise highly depleted harzburgites to fertile lherzolites as well as metasomatically overprinted peridotites. Unlike most primitive mantle-derived magmas, which display very limited Ti isotope variations, δ49Ti (deviation of 49Ti/47Ti from the OL-Ti standard) values of the Horoman peridotites vary from –1.523 ± 0.029 to 0.547 ± 0.015‰ (2SD), spanning a total δ49Ti range of 2.07‰. Heavy, continental crust-like Ti isotope compositions are correlated with Nb/Th and are likely related to metasomatism of the mantle wedge above the Hidaka subduction zone. In such a scenario, isotopically heavy Ti was inherited from the subducted terrigenous sediments and might have been further enhanced by Ti isotope fractionation during mobilisation from the slab. Significant δ49Ti differences between coexisting clino- and orthopyroxene (Δ49Ti opx-cpx = 0.16–0.29‰) and notably light Ti isotope compositions (δ49Ti = −1.523 ± 0.029 to −0.677 ± 0.036‰, 2SD) recorded in highly refractory peridotites might be related to kinetic diffusion-driven isotope fractionation during fluid/melt percolation. The analysed ultrapotassic rocks display distinctly high δ49Ti values (0.114 ± 0.040 to 0.290 ± 0.030‰, 2SD) compared to the majority of primitive mantle-derived magmas. The observed enrichment in heavy Ti isotopes likely originates from recycled continental material characterised by high δ49Ti, in line with their derivation from strongly metasomatised mantle sources. Our results demonstrate the presence of significant small-scale Ti isotope heterogeneity within the upper mantle. [ABSTRACT FROM AUTHOR]

The Titanium (Ti) isotope compositions of felsic rocks are heavier than their mafic counterparts, and alkaline magmas develop heavier Ti isotope compositions compared to other magma series during magmatic differentiation. Both observations are interpreted to reflect the preferential sequestration of light Ti isotopes in Fe-Ti oxides, such as rutile, ilmenite and titanomagnetite. However, such interpretations so far rely on whole rock studies of cogenetic magmatic samples and the detailed mechanics of oxide-melt equilibrium on the Ti isotope composition of magmas is poorly constrained. To address this, we have measured the Ti isotope composition of co-existing Fe-Ti oxides and groundmass or silicate melt in both natural lavas from contrasting tectonic settings (Heard Island and Santorini), and experimental run products (rutile-melt). All Fe-Ti oxide phases are consistently isotopically lighter than their respective host groundmass or silicate melt, with the magnitude of Δ49/47Ti oxide-melt increasing from rutile to ilmenite, and titanomagnetite. The observed difference in Ti isotope fractionation between rutile-melt experiments and ilmenite-groundmass pairs is primarily reflective of small differences in their Ti O bond length, with ilmenite being isotopically lighter (Δ49/47Ti ilmenite-melt extrapolated to 1000 K = −0.600 ± 0.035‰) compared to rutile (Δ49/47Ti rutile-melt at extrapolated to 1000 K = −0.404 ± 0.099‰) due to slightly longer Ti O bonds in ilmenite. In contrast, the variation in Δ49/47Ti observed between titanomagnetite-groundmass pairs increases as a function of increasing TiO 2 content (increasing ulvöspinel component) in titanomagnetite, with Δ49/47Ti titanomagnetite-melt values extrapolated to 1000 K ranging from −0.811 to −1.451‰ in Ti-rich titanomagnetite (21–23 wt.% TiO 2 ; Usp 66-73) from Heard Island compared to −0.673‰ to −0.863 in Santorini (14–15 wt.% TiO 2 ; Usp 45-49). We interpret this to result from a weaker and distorted crystal lattice due to changes in the local cationic environment resulting from exchange of smaller Fe3+ ions with larger Fe2+ ions during magnetite-ulvöspinel solid solution. Our results are consistent with fractionation factors inferred from Ti isotopic analyses of mineral separates and ab-initio calculations. We use these fractionation factors in combination with Ti isotope fractionation factors for silicate minerals recalculated from previous studies, along with petrologic information to model the behaviour of Ti isotopes during partial melting of Earth's mantle as well as reproducing the observed variation in δ49/47Ti of differentiated magmas from distinct geodynamic settings. [ABSTRACT FROM AUTHOR]

Towards a deeper understanding of the local structure of the B-site in (100-x)(Bi1/2Na1/2)TiO3- xBaTiO3 (BNT-xBT) with 0 ≤ x ≤ 15, solid-state nuclear magnetic resonance (NMR) spectra of the titanium isotopes 47Ti and 49Ti were investigated. The 47,49Ti NMR spectra of BNT-xBT indicate a disordered local structure for the B-site of these perovskites. The line-shape of the titanium NMR spectra of BNT-xBT samples is found to be independent on the barium content. This fact implies that the local structure of the B-site remains invariant with respect to the structural changes that result from the chemical modification with barium. The analysis of 47,49Ti NMR spectra supports the hypothesis that the main structural changes across the morphotropic phase boundary in these solid-solutions are constrained to the A-site and are related to the tilting of rigid oxygen octahedra. [ABSTRACT FROM AUTHOR]

Calcium-aluminum-rich inclusions (CAIs) are highly refractory objects found in different chondrite groups and represent some of the oldest known solids of the Solar System. As such, CAIs provide key information regarding the conditions prevailing in the solar protoplanetary disk as well as subsequent mixing and transport processes. Many studies have investigated CAIs for their isotopic compositions and reported nucleosynthetic isotope anomalies in numerous elements, which are typically explained by the variable incorporation of isotopically highly anomalous presolar phases. However, with the exception of 54Cr-enriched nanospinels, the exact presolar phases responsible for the isotopic heterogeneities are yet to be identified. To address this issue, we here present in-situ Ti isotopic analyses obtained on a diverse set of CAIs from various CV3 chondrites. The in-situ measurements were performed by targeting individual mineral phases of 15 CAIs with laser-ablation mass spectrometry and indicate significant inter- and intra-CAI isotopic heterogeneity in the neutron-rich isotope 50Ti. This is particularly pronounced for primitive fine-grained CAIs, whereas coarse-grained CAIs, which have been subject to melting, exhibit smaller degrees of Ti isotopic heterogeneity. To further investigate this Ti isotopic heterogeneity, we additionally obtained Ti isotopic compositions of sequential acid leachates from two fine-grained and two coarse-grained CAIs derived from CV3 chondrites. In contrast to potential expectations from the first part of the study, we do not observe any significant intra-CAI Ti isotopic heterogeneity between the different leaching steps. The lack of intra-CAI Ti isotopic heterogeneity in the acid leachate samples of this study likely reflects that the leaching procedure is unable to efficiently separate the carriers of isotopically anomalous Ti in CAIs. By comparing the bulk CAI Ti isotope compositions with Ti isotope data for hibonite-rich objects from the literature, we find that the range of Ti isotope compositions recorded by CAIs from various chondrite groups can be accounted for by the averaging of hibonite grains. In turn, the variable Ti isotope compositions of hibonite grains can be explained by the averaging of isotopically diverse presolar grains present in the Sun's parental molecular cloud. This effect of averaging is statistically supported by the central limit theorem, and the concept has the potential to be useful for other isotopic systems. [ABSTRACT FROM AUTHOR]

Equilibria between Ti oxides and silicate melt lead to Ti isotope fractionation in terrestrial samples, with isotopically light Ti oxides and isotopically heavy coexisting melt. However, while Ti is mostly tetravalent in terrestrial samples, around 10% of the overall Ti is trivalent at fO2 relevant to lunar magmatism (~ IW-1). The different valences of Ti in lunar samples, could additionally influence Ti stable isotope fractionation during petrogenesis of lunar basalts to an unknown extent. We performed an experimental approach using gas mixing furnaces to investigate the effect of Ti oxide formation at different fO2 on Ti stable isotope fractionation during mare basalt petrogenesis. Two identical bulk compositions were equilibrated simultaneously during each experiment to guarantee comparability. One experiment was investigated with the EPMA to characterize the petrology of experimental run products, whereas the second experiment was crushed, and fabricated phases (i.e., oxides, silicates and glass) were handpicked, separated and digested. An aliquot of each sample was mixed with a Ti double-spike, before Ti was separated from matrix and interfering elements using a modified HFSE chemistry. Our study shows fO2-dependent fractionation within seven samples from air to IW-1, especially ∆49Tiarmalcolite-melt and ∆49Tiarmalcolite-orthopyroxene become more fractionated from oxidized to reduced conditions (− 0.092 ± 0.028- − 0.200 ± 0.033 ‰ and − 0.089 ± 0.027- − 0.250 ± 0.049 ‰, respectively), whereas ∆49Tiorthopyroxene-melt shows only a minor fractionation (− 0.002 ± 0.017-0.050 ± 0.025 ‰). The results of this study show that Ti isotope fractionation during mare basalt petrogenesis is expected to be redox dependent and mineral-melt fractionation as commonly determined for terrestrial fO2 may not be directly applied to a lunar setting. This is important for the evaluation of Ti isotope fractionation resulting from lunar magmatism, which takes place under more reducing conditions compared to the more oxidized terrestrial magmatism. [ABSTRACT FROM AUTHOR]

Iron mobilization during continental weathering was pervasive before the Great Oxidation Event (GOE) that started at around 2.43 billion years (Ga) ago, due to the soluble nature of reduced iron. However, various geochemical proxies indicate transient oxygenation during deposition of the Mesoarchean (∼2.95 Ga) Pongola Supergroup, South Africa, which suggests that continental weathering could have also occurred under transiently oxic conditions before the GOE. We analyzed trace elemental and Fe, Ti, and Cr isotopic compositions of the ca. 2.95 Ga Denny Dalton paleosol in the Pongola Supergroup to better understand continental weathering and redox conditions in the ancient critical zone, and the nature of geochemical fluxes from the continents to the oceans and marine sediments. Iron isotope systematics are consistent with a model where Fe was released during intense leaching from the paleosol to concentrate in Fe-rich groundwaters in the deeper part of the soil horizon. We show for the first time that Fe isotopic fractionation during Mesoarchean continental weathering was limited, and Fe enrichments and depletions are coupled with those of divalent transition metals, Co, Ni, and particularly Zn. This suggests that Fe redox cycling was not involved in paleosol formation, and Fe2+ was mobilized under anoxic conditions. Chromium isotopes are also unfractionated relative to the parent igneous rock in this paleosol, which precludes removal of isotopically heavy Cr6+ and thus supports anoxic continental weathering. We show that previously reported Cr isotopic fractionation in another Denny Dalton paleosol profile does not follow a Cr6+ leaching trend, but instead scales with Cr enrichment and may reveal Cr enrichment from post-burial fluids. Thus, there is no clear evidence for an oxidative continental weathering during deposition of the Pongola Supergroup. Titanium isotopes are not significantly fractionated in the paleosol, suggesting that continental weathering and erosion in the Archean did not fractionate Ti isotopes. Similarly, Ni/Co and Th/Sc ratios are reasonably conserved, which validates their use as a robust proxy for upper continental crust composition in shales, whereas La/Sc, Cr/Zn and Cr/U ratios are highly variable relative to the provenance composition, which suggests that caution should be used when applying these ratios in shale studies of the ancient upper continental crust composition. [ABSTRACT FROM AUTHOR]

Isoscalar monopole and dipole transitions are investigated in the medium and heavier systems, such as 44 Ti and even 104 - 110 Te nuclei by employing the macroscopic α cluster model of α + 40 Ca and α + 100 - 106 Sn , respectively. Theoretical calculations predict that the strengths of the monopole and dipole transitions are strongly enhanced in the excitation energy below 10 MeV. These low-lying enhancements are induced by the excitation in the relative motion of the α cluster and the residual nucleus, and the magnitudes of the transition matrix element are comparable to the single nucleon excitation, which requires much higher excitation energy than the energy for the α excitation. The electric dipole strength is also calcluated for 135 Cs with the cluster model of α + 131 I , which is a kind of nuclear waste. The application of the monopole and dipole transitions involving the α emission to the nuclear transmutation of the nuclear wastes is also discussed. [ABSTRACT FROM AUTHOR]

• Magma series show distinct Ti isotope fractionation patterns during differentiation. • Fe and Ti content of parental melts is the main control on Ti isotope fractionation. • Redox state and water content are secondary controls for arc magmas. Titanium offers a burgeoning isotope system that has shown significant promise as a tracer of magmatic processes. Recent studies have shown that Ti isotopes display significant mass-dependent variations linked to the crystallisation of Fe-Ti oxides during magma differentiation. We present a comprehensive set of Ti isotope data for a range of differentiation suites from alkaline (Ascension Island, Afar and Heard Island), calc-alkaline (Santorini) and tholeiitic (Monowai seamount and Alarcon Rise) magma series to further explore the mechanics of Ti isotope fractionation in magmas. Whilst all suites display an increase in δ49/47Ti (deviation in 49Ti/47Ti of a sample relative to the OL-Ti reference material) during magma differentiation relative to indices such as increasing SiO 2 and decreasing Mg#, our data reveal that each of the three magma series have contrasting δ49/47Ti fractionation patterns over comparable ranges of SiO 2 and Mg#. Alkaline differentiation suites from intraplate settings display the most substantial range of variation (δ49/47Ti = +0.01 to +2.32‰), followed by tholeiites (−0.01 to +1.06‰) and calc-alkaline magmas (+0.06 to +0.64‰). Alkaline magmas possess high initial melt TiO 2 contents which enables early saturation of ilmenite + titanomagnetite and a substantial degree of oxide crystallisation, whereas tholeiitic and calc-alkaline suites crystallise fewer oxides and have titanomagnetite as the dominant oxide phase. Positive slopes of FeO*/TiO 2 vs. SiO 2 during magma differentiation are related to high degrees of crystallisation of Ti-rich oxides (i.e. ilmenite). Bulk solid-melt Ti isotope fractionation factors co-vary with the magnitude of the slope of FeO*/TiO 2 vs. SiO 2 during magma differentiation.This indicates that the modal abundance and composition of the Fe-Ti oxide phase assemblage, itself is controlled by melt composition, governs Ti isotope fractionation during magma differentiation. In addition to this overall control, hydrous, oxidised calc-alkaline suites display a resolvable increase in δ49/47Ti at higher Mg# relative to drier and more reduced tholeiitic arc suites. These subparallel Ti isotope fractionation patterns are best explained by the earlier onset of oxide segregation in arc magmas with a higher oxidation state and H 2 O content. This indicates the potential of Ti isotopes to be utilised as proxies for geodynamic settings of magma generation. [ABSTRACT FROM AUTHOR]

• AOAs and CAIs formed from isotopically comparable materials. • AOAs and CAIs formed in a common region of the protoplanetary disk. • AOAs may be one of many chondrule precursor components. • The protoplanetary disk experienced a large-scale change in isotopic composition. Amoeboid olivine aggregates (AOAs) are the most abundant type of refractory inclusions found in most carbonaceous chondrite groups. AOAs are thought to be genetically related to calcium-aluminum-rich inclusions (CAIs) and potential chondrule precursor components, although the precise physical and temporal details of AOA formation and their relationship to other chondritic components remain unclear. In this study, we measured the chromium and titanium isotopic compositions of eight AOAs from four different CV chondrites with the goal of evaluating potential genetic links between AOAs, CAIs, and chondrules. These are the first Cr and Ti isotopic data reported beyond a single AOA previously measured for Cr and a different single AOA previously measured for Ti. The results presented here show that the ε54Cr and ε50Ti isotopic compositions of AOAs are indistinguishable from those of CAIs, suggesting that AOAs and CAIs formed from a common region of the disk. We also demonstrate, based on the comparison of the Cr and Ti isotopic composition of AOAs to previously measured chondrules, that mixing between AOAs and an NC compositional endmember alone cannot fully explain the range of measured chondrule compositions. Although AOAs may have been important chondrule precursor components along with AOA olivine, CAIs, fragments of earlier generation chondrules, and fine-grained matrix material, this observation requires another currently unknown component to be involved in chondrule formation. [ABSTRACT FROM AUTHOR]

• Global primitive arc lavas (Mg# ≥60) display notable δ49/47Ti heterogeneity. • Residual rutile imposes high δ49/47Ti of 0.24 ± 0.06 ‰ on hydrous, silicic slab melts. • Primitive Aleutian rhyodacites have the same δ49/47Ti as predicted for slab melts. • A variably diluted signature of slab melts is found in all eight subduction zones. • A slab melt component is required to generate silicic primitive arc lavas. It is still a matter of intense debate to what extent partial melting of the subducting slab contributes to arc magmatism in modern subduction zones. In particular, it is difficult to differentiate between silicate melts formed by partial melting of the slab, and aqueous fluids released during subsolidus dehydration as the main medium for slab-to-mantle wedge mass transfer. Here we use δ49/47Ti (the deviation in 49Ti/47Ti of a sample to the OL-Ti reference material) as a robust geochemical tracer of slab melting. Hydrous partial melting of subducted oceanic crust and the superjacent sedimentary layer produces silicic melts in equilibrium with residual rutile. Modelling shows that such silicic slab melts have notably higher δ49/47Ti (+0.24 ± 0.06 ‰) than their protolith due to the strong preference of rutile for the lighter isotopes of Ti. In contrast, even highly saline fluids cannot carry Ti from the slab and hence hydrous peridotite partial melts have δ49/47Ti similar to mid-ocean ridge basalts (MORB; ca. 0 ‰). Primitive (Mg# ≥60) arc lavas from eight subduction zones that are unaffected by fractional crystallisation of Fe-Ti oxides show a more than tenfold larger variation in δ49/47Ti than found in MORB. In particular, primitive arc lavas display a striking correlation between SiO 2 content and δ49/47Ti that ranges from island arc basalts overlapping with MORB, to primitive rhyodacites with δ49/47Ti up to 0.26 ‰ erupted in the western Aleutian arc. The elevated δ49/47Ti of these primitive arc lavas provides conclusive evidence for partial melts of the slab as a key medium for mass transfer in subduction zones. The Aleutian rhyodacites represent a rare example of slab melts that have traversed the mantle wedge with minimal modification. More commonly, slab melts interact with the mantle wedge to form an array of primary arc magmas that are a blend of slab- and peridotite-derived melt. We identify primitive arc lavas with a clearly resolvable slab melt signature in all eight subduction zone localities, confirming that slab melting is prevalent in modern subduction zones. [ABSTRACT FROM AUTHOR]

A method for preparation of Ti-doped NaAlH4 with high hydrogen capacity was developed, in which the NaH/Al mixture was mechanically milled with a catalytic amount of KH together with metallic Ti. The addition of KH was found to result in a pronounced improvement in the dehydriding performance of the Na3AlH6/NaH+Al step. As a result, the practical cycling hydrogen capacity has been markedly enhanced from 3.3 wt % for the Ti-doped hydride to 4.7 wt % for KH+Ti co-doped material. Moreover, the pronounced enhancement on hydrogen capacity arising upon adding KH was observed to persist in the following dehydrogenation/hydrogenation cycles. Structural investigation shows that the addition of KH has led to a lattice expansion. Moreover, it was found that the enthalpy change of the Na3AlH6/NaH+Al decomposition step underwent a considerable decrease upon adding KH. Therefore, the observed property improvement may be ascribed to a favorable thermodynamic adjustment arising upon the addition of KH. [ABSTRACT FROM AUTHOR]

Combined determination of Cr and Ti isotopes of planetary materials offers a means with which to investigate their genetic relationship and the evolution of the protoplanetary disk. Here, we report the new sequential chemical separation procedure for combined Cr and Ti isotope ratio measurements. It comprises three steps: (a) Fe removal using AG1‐X8 anion exchange resin, (b) Ti separation using TODGA resin and (c) Cr separation using AG50W‐X8 cation exchange resin (with one additional step of Ti purification using AG1‐X8 anion exchange resin for samples having high Cr/Ti and Ca/Ti ratios). We applied the proposed procedure to terrestrial and meteorite samples with various compositions. Typical recovery rates of 90–100% were achieved with total procedural Cr and Ti blanks of 3–5 and 2–3 ng, respectively. We measured the Cr and Ti isotope compositions of the separated samples using thermal ionisation mass spectrometry and multiple collector‐inductively coupled plasma‐mass spectrometry, respectively. Our Cr and Ti isotope data were found to be consistent with those of previous studies of individual Cr and Ti isotopic compositions of the meteorites. These results demonstrate the capability of our separation method when applied to combined high‐precision Cr and Ti isotope analyses for single digests of planetary materials. Key Points: Sequential chemical separation for combined Cr and Ti isotope ratio measurements has been developed. Our new method enables isotope analyses of 3 μg of Cr and 1.5 μg of Ti. The combined isotope analyses of primitive meteorite components will facilitate understanding of the evolution of the proto‐planetary disk. [ABSTRACT FROM AUTHOR]

Abstract The present work deals with the development of a novel photocatalyst to decompose most of the organic pollutants. This work provides a strategy for reproducible high-pressure phases of TiO 2 at ambient conditions through nebulizer spray pyrolysis (NSP) technique by varying the substrate temperatures of 200–500 °C using titanium (IV) isopropoxide as a titanium precursor. The structural, morphological, optical and electrical properties of the deposited TiO 2 thin films were investigated by using X-ray diffraction, field emission scanning electron microscopy, UV–Visible spectroscopy, Hall effect and temperature dependent resistivity measurements, respectively. The structural analysis confirms that the films deposited at higher substrate temperature are crystallized in TiO 2 –II phase having polycrystalline nature with good crystalline quality and also pressure induced amorphous phases were also observed for the films deposited at lower substrate temperatures. Deposited films have the uniform surface with homogeneity and porous nature which is suitable for enhanced photocatalytic applications. Electrical measurements show that the films are having n-type behavior with appreciable carrier mobility and concentration. The use of high-pressure TiO 2 -II phase for higher photocatalytic efficiency was demonstrated. Highlights • First report on crystalline, high pressure TiO 2 –II thin films deposited at low temperature using spray pyrolysis. • Possibility of formation of pressure induced phases in nebulizer spray pyrolysis was discussed. • Optoelectronic property of the TiO 2 -II phase was completely studied. [ABSTRACT FROM AUTHOR]

Titanium(IV) isopropoxide and ethylmagnesium bromide catalyzed reaction of 2-alkynylamines with Et2Zn, followed by deuterolysis/ hydrolysis and iodinolysis, affords substituted (Z)-pent-2-en-2,5- d2-1-amines, (Z)-pent-2-en-1-amines (65-88%), and substituted (Z)- 2,5-diiodopent-2-en-1-amines (55-63%). It is suggested that the reaction proceeds through the formation of cyclic organotitanium derivatives. The reaction between 1-alkynylphosphines and Et2Zn in the presence of catalytic amounts of Ti(O-iPr)4 and EtMgBr leads to trisubstituted 1-alkenylphosphine oxides with high regioselectivity and stereoselectivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Image 1 Abstract An investigation of 53 saturated absorption lines of titanium at wavelengths ranging from 695 to 1005 nm is performed. In addition, transitions 3 d 34 s a 5 F J → 3 d 34 p y 5 F J (J = 3, 4, 5) in the ultraviolet range are measured. The isotope lines of 46Ti, 48Ti, and 50Ti are clearly observed for 53 transitions. A facing target sputtering system containing a magnetic field is used as a sample cell of titanium in this experiment. The Zeeman effect in a hyperfine structure is calculated for the condition of an intermediate field approximation to determine the unperturbed line positions in the odd mass isotopes 47Ti and 49Ti. For all observed transitions, the King plot analysis is performed to determine the electronic factors of the field shift and specific mass shift. [ABSTRACT FROM AUTHOR]

Abstract X-ray diffraction (XRD), grazing incidence X-ray diffraction (GIXRD) and X-ray reflectometry (XRR) techniques were applied for analysis of titanium (Ti) and titanium (IV) oxide (TiO 2) nanolayers with thickness of 25 nm, 50 nm and 75 nm deposited on silicon, quartz and BK7 glass substrates. The aim of studies was investigating the crystal structure and morphology of the nanolayers in dependence on the substrate type. The chemical phases of nanolayers and substrates were determined by using the XRD and GIXRD measurements. The benefits of applying low angle GIXRD and XRR analytical techniques, both for substrate and nanofilm analysis, is discussed based on theoretical calculations and simulations. Additional, analytical capabilities of the XRR technique to nanolayer and substrate morphology analysis are presented. Simulated XRR curves for titanium (Ti) and titanium (IV) oxide nanolayers are discussed depending on the substrate type as well as the substrate and nanolayer roughnesses. Experimental reflectometry curves are presented for all titanium and titanium (IV) oxide nanolayers deposited on the different substrates. As the result of the XRR analysis, the nanolayer thickness and roughness together with substrate roughness are estimated. The mean values of the Ti and TiO 2 layer thickness and roughness are presented for all studied samples. The largest roughness, both for nanolayers and for substrates, is obtained for BK7 glass material. In the manuscript, sample properties, experimental setups and measurement conditions are presented in details. Highlights • Grazing incidence X-ray techniques used for analysis of Ti and TiO2 nanolayers. • Analysis of the grazing incidence X-ray diffractogram of the layers. • Analysis of the reflectometry curves and layer thickness and roughness estimation. • Discussion of the influence of the substrates on the nanolayers morphology. [ABSTRACT FROM AUTHOR]

Indirect evidence for the presence of a felsic continental crust, such as the elevated 49Ti/47Ti ratios in Archean shales, has been used to argue for ongoing subduction at that time and therefore plate tectonics. However, rocks of intermediate to felsic compositions can be produced in both plume and island arc settings. The fact that Ti behaves differently during magma differentiation in these two geological settings might result in contrasting isotopic signatures. Here, we demonstrate that, at a given SiO2 content, evolved plume rocks (tholeiitic) are more isotopically fractionated in Ti than differentiated island arc rocks (mainly calc-alkaline). We also show that the erosion of crustal rocks from whether plumes (mafic in average) or island arcs (intermediate in average) can all produce sediments having quite constant 49Ti/47Ti ratios being 0.1-0.3 per mille heavier than that of the mantle. This suggests that Ti isotopes are not a direct tracer for the SiO2 contents of crustal rocks. Ti isotopes in crustal sediments are still a potential proxy to identify the geodynamical settings for the formation of the crust but only if combined with additional SiO2 information. [ABSTRACT FROM AUTHOR]

Abstract Titanium and calcium are both refractory lithophile elements. Significant stable isotopic variations on Ti and Ca have been documented within calcium, aluminum-rich inclusions (CAIs) in carbonaceous chondrites. To trace the condensation history of Ti in the solar nebula, we conducted a high-precision double-spike Ti stable isotopic study on a large set of chondrites. The studied chondrites have a homogeneous bulk Ti stable isotopic composition (δ 49/47Ti IPGP-Ti = −0.069 ± 0.018‰, 2se, n = 22, i.e., the per mil deviation of the 49Ti/47Ti ratios relative to the IPGP-Ti reference material). The homogeneity across eleven chondrite groups implies that chondrites have acquired, through the condensation sequence at equilibrium, the average stable isotopic composition of Ti in the refractory solids that condensed early in the solar nebula. In contrast, the light Ca stable isotopic compositions of bulk chondrites can be attributed to either the presence of CAIs (CV-, CM- and CO-type) or parent-body aqueous alteration (CR- and CI-type). [ABSTRACT FROM AUTHOR]

Understanding the relationships between and among chondritic components of various chondrite groups is of prime importance for deciphering the dynamics of material transport and planetary accretion in the early Solar System. Here we obtain insights into these processes and the reservoirs present by investigating the nucleosynthetic Ti isotopic signatures of individual Ca,Al-rich inclusions (CAIs) and Na–Al-rich chondrules from ordinary and CO chondrites. This specific type of chondrule is of interest as it is thought to have incorporated refractory, CAI-like material as precursors. Our data show that CAIs from ordinary and CO chondrites exhibit 50 Ti excesses that are indistinguishable from CV CAIs, and thus indicate a common source reservoir for refractory inclusions in ordinary, CO, and CV chondrites. Na–Al-rich chondrules from CO chondrites also show 50 Ti excesses, indicating the presence of CAIs from this reservoir in the precursor materials of CO chondrules. In contrast, Na–Al-rich chondrules from ordinary chondrites show no 50 Ti excesses and are indistinguishable from the bulk values for ordinary chondrites. Thus, known CAIs cannot have been the refractory precursor of the Na–Al-rich chondrules in ordinary chondrites. Consequently, within the accretion region of the ordinary chondrites, two different types of refractory components must have existed: (1) a 50 Ti-enriched refractory component that is present as CAIs and either arrived at the accretion region of the ordinary chondrites after chondrule formation, or was only present in insignificant amounts, and (2) another type of refractory material without a 50 Ti excess, which was involved as precursor in the chondrule formation process. Our data thus imply that refractory components with condensation signatures must have formed in at least two isotopically distinct nebular regions. These may be related to non-carbonaceous and carbonaceous source regions, that is, the inner and outer Solar System, divided by the early formation of Jupiter. [ABSTRACT FROM AUTHOR]

Previous studies have shown that CV and CM chondrites incorporated Ca, Al-rich inclusions (CAIs) with different isotopic characteristics, which may represent different snapshots in the isotopic evolution of the early Solar System. To better understand how the isotopic characteristics of CAIs vary between different chondrite groups, we have studied calcium and titanium isotopes in CAIs from CM, CO, and CR chondrites. We show that all three chondrite groups contain CAIs with large anomalies in 48 Ca and/or 50 Ti (10s of ‰ or 100s of ε -units) as well as CAIs with no anomalies resolved beyond measurement uncertainties. Isotopically, the anomalous CO and CR chondrite CAIs resemble the platy hibonite crystals (PLACs) from CM chondrites, but they are more mineralogically complex. The new data are consistent with the well-established mutual exclusivity relationship between incorporation of 26 Al and the presence of large anomalies in 48 Ca and 50 Ti. The two highly anomalous CO chondrite CAIs have correlated anomalies in 46 Ti and 50 Ti, while most other highly anomalous CAIs do not. This result could indicate that the reservoir with coupled 46 Ti and 50 Ti that was sampled by bulk meteorites and CV chondrite CAIs already existed before arrival and/or homogeneous distribution of 26 Al in the protoplanetary disk. Among the studied CM chondrite CAIs are ten spinel-hibonite inclusions (SHIBs) with known oxygen isotopic compositions. Our results show that these objects sampled a reservoir that was well-mixed in oxygen, calcium, and titanium isotopes. We further show that SHIBs tend to be slightly enriched in the heavy calcium isotopes, suggesting that their formation history was different from CV chondrite CAIs. [ABSTRACT FROM AUTHOR]

Typical reconstructions of historic heliospheric magnetic field (HMF) BHMF are based on the analysis of the sunspot activity, geomagnetic data or on measurement of cosmogenic isotopes stored in terrestrial reservoirs like trees (14C) and ice cores (10Be). The various reconstructions of BHMF are however discordant both in strength and trend. Cosmogenic isotopes, which are produced by galactic cosmic rays impacting on meteoroids and whose production rate is modulated by the varying HMF convected outward by the solar wind, may offer an alternative tool for the investigation of the HMF in the past centuries. In this work, we aim to evaluate the long-term evolution of BHMF over a period covering the past twenty-two solar cycles by using measurements of the cosmogenic 44Ti activity (τ1/2 = 59.2 ± 0.6 yr) measured in 20 meteorites which fell between 1766 and 2001. Within the given uncertainties, our result is compatible with a HMF increase from 4.87+0.24-0.30 nT in 1766 to 6.83+0.13-0.11 nT in 2001, thus implying an overall average increment of 1.96+0.43-0.35 nT over 235 years since 1766 reflecting the modern Grand maximum. The BHMF trend thus obtained is then compared with the most recent reconstructions of the near-Earth HMF strength based on geomagnetic, sunspot number, and cosmogenic isotope data. [ABSTRACT FROM AUTHOR]

Titanium isotopic compositions (mass-dependent fractionation and isotopic anomalies) were measured in 46 calcium-, aluminum-rich inclusions (CAIs) from the Allende CV chondrite. After internal normalization to 49 Ti/ 47 Ti, we found that ε 50 Ti values are somewhat variable among CAIs, and that ε 46 Ti is highly correlated with ε 50 Ti, with a best-fit slope of 0.162 ± 0.030 (95% confidence interval). The linear correlation between ε 46 Ti and ε 50 Ti extends the same correlation seen among bulk solar objects (slope 0.184 ± 0.007). This observation provides constraints on dynamic mixing of the solar disk and has implications for the nucleosynthetic origin of titanium isotopes, specifically on the possible contributions from various types of supernovae to the solar system. Titanium isotopic mass fractionation, expressed as δ′ 49 Ti, was measured by both sample-standard bracketing and double-spiking. Most CAIs are isotopically unfractionated, within a 95% confidence interval of normal, but a few are significantly fractionated and the range δ′ 49 Ti is from ∼−4 to ∼+4. Rare earth element patterns were measured in 37 of the CAIs. All CAIs with significant titanium mass fractionation effects have group II and related REE patterns, implying kinetically controlled volatility fractionation during the formation of these CAIs. [ABSTRACT FROM AUTHOR]

The article discusses the study that show the delayed formation of silicon carbide (SiC) and carbonaceous grains in type II supernovae (SNe). Topics mentioned include the correlation of the dust grains between Silicon (Si) and Titanium (Ti) excesses, the formation of dust grains showed by Vanadium (V) -Ti chronometer after two years when the parent stars exploded, and the result which supports the calculations on dust condensation of the delayed formation.

Clay minerals are versatile materials with numerous industrial applications. Their unique layered structure can act as a host for many optically active species. The synthesis and luminescence properties of chlorohectorite clays are now reported for the first time. The synthesized clays are composed of quasi-circular nanoparticles with diameters around 20–30 nm showing blue/green emission and persistent luminescence with a duration of ca. 5 s. The luminescence features are associated with titanium impurities in the chlorohectorite structure. It is shown that Ti can act as activator ion even at low concentrations: the XRF and ICP-MS measurements of the chlorohectorite materials indicate a Ti concentration around 60 ppm originating from the precursors. The XPS measurements of the clay materials showed the Ti 2p 3/2 signals at 457.8 and 458.9 eV associated with Ti 3+ and Ti IV , respectively. The excitation spectra confirm Ti 3+ as the luminescent center in the chlorohectorites through the bands at 287 and 370 nm, related to the e − ( O 2 − ( 2 p ) ) → Ti IV charge transfer and the electronic transitions from the t 2g to e g levels of Ti 3+ , respectively. The persistent luminescence properties are due to structural defects common for layered silicates. [ABSTRACT FROM AUTHOR]

Titanium isotopes recorded in glacial diamictites with depositional ages between 2.9 and 0.3 Ga show that the upper continental crust became significantly more felsic relative to the present-day crust during the amalgamation of the Paleoproterozoic Nuna and the Neoproterozoic Gondwana supercontinents. This can be attributed to the continental collisions involved in the assembly of Nuna and Gondwana. The resulting high topographic relief of Nuna and Gondwana orogens must have resulted in an enhanced erosional supply from the continents to oceans. The step changes in the development of organismal complexity from prokaryotes to eukaryotes, and eventually metazoans, appear to be temporally correlated to instances where collisional mountain-building sustained an elevated nutrient supply from the continents to oceans. The nutrient surge associated with the rise of the Gondwana mountains likely provided the necessary impetus for the Neoproterozoic ecological expansion of eukaryotes and the eventual radiation of metazoans. A similar link between the enhanced nutrient supply from Nuna mountains and the radiation of early eukaryotes is plausible, although its mechanistic underpinnings remain unclear. The termination of Nuna orogeny and its transition to Rodinia without significant breakup and subsequent collisional orogenesis corresponds to the long lull in Earth's redox and biological evolution in its middle age. • Pronounced variations in the felsic character of Proterozoic upper crust. • These variations can be temporally linked to the assembly of Nuna and Gondwana. • High continental relief brackets the mid-Proterozoic lull in eukaryote evolution. • Gondwana orogeny likely facilitated the Neoproterozoic redox and biological changes. • Enhanced erosion linked to Nuna orogeny may have aided the radiation of eukaryotes. [ABSTRACT FROM AUTHOR]

Earth exhibits a dichotomy in elevation and chemical composition between the continents and ocean floor. Reconstructing when this dichotomy arose is important for understanding when plate tectonics started and how the supply of nutrients to the oceans changed through time.We measured the titanium isotopic composition of shales to constrain the chemical composition of the continental crust exposed to weathering and found that shales of all ages have a uniform isotopic composition. This can only be explained if the emerged crust was predominantly felsic (silica-rich) since 3.5 billion years ago, requiring an early initiation of plate tectonics.We also observed a change in the abundance of biologically important nutrients phosphorus and nickel across the Archean-Proterozoic boundary, which might have helped trigger the rise in atmospheric oxygen. [ABSTRACT FROM AUTHOR]

Titanium isotopes are potential tracers of processes of evaporation/condensation in the solar nebula and magmatic differentiation in planetary bodies. To gain new insights into the processes that control Ti isotopic variations in planetary materials, 25 komatiites, 15 chondrites, 11 HED-clan meteorites, 5 angrites, 6 aubrites, a martian shergottite, and a KREEP-rich impact melt breccia have been analyzed for their mass-dependent Ti isotopic compositions, presented using the δ 49 Ti notation (deviation in permil of the 49 Ti/ 47 Ti ratio relative to the OL-Ti standard). No significant variation in δ 49 Ti is found among ordinary, enstatite, and carbonaceous chondrites, and the average chondritic δ 49 Ti value of +0.004 ± 0.010‰ is in excellent agreement with the published estimate for the bulk silicate Earth, the Moon, Mars, and the HED and angrite parent-bodies. The average δ 49 Ti value of komatiites of −0.001 ± 0.019‰ is also identical to that of the bulk silicate Earth and chondrites. OL-Ti has a Ti isotopic composition that is indistinguishable from chondrites and is therefore a suitable material for reporting δ 49 Ti values. Previously published isotope data on another highly refractory element, Ca, show measurable variations among chondrites. The decoupling between Ca and Ti isotope systematics most likely occurred during condensation in the solar nebula. Aubrites exhibit significant variations in δ 49 Ti, from −0.07 to +0.24‰. This is likely due to the uniquely reducing conditions under which the aubrite parent-body differentiated, allowing chalcophile Ti 3+ and lithophile Ti 4+ to co-exist. Consequently, the observed negative correlation between δ 49 Ti values and MgO concentrations among aubrites is interpreted to be the result of isotope fractionation driven by the different oxidation states of Ti in this environment, such that isotopically heavy Ti 4+ was concentrated in the residual liquid during magmatic differentiation. Finally, KREEPy impact melt breccia SaU 169 exhibits a heavy δ 49 Ti value of +0.330 ± 0.034‰ which is interpreted to result from Ti isotopic fractionation during ilmenite precipitation in the late stages of lunar magma ocean crystallization. A Rayleigh distillation calculation predicts that a δ 49 Ti value of +0.330‰ is achieved after removal of 94% of Ti in ilmenite. [ABSTRACT FROM AUTHOR]

Lifetimes of the 2 1 + states in 44 Ti, 48,50 Cr, and 52 Fe were determined with high accuracy exploiting the recoil distance Doppler-shift method. The reduced E2 transition strengths of 44 Ti and 52 Fe differ considerably from previously known values. A systematic increase in collectivity is found for the N = Z nuclei compared to neighboring isotopes. The B ( E2 ) values along the Ti, Cr, and Fe isotopic chains are compared to shell-model calculations employing established interactions for the 0 f 1 p shell, as well as a novel effective shell-model Hamiltonian starting from a realistic nucleon–nucleon potential. The theoretical approaches underestimate the B ( E2 ) values for the lower-mass Ti isotopes. Strong indication is found for particle-hole cross-shell configurations, recently corroborated by similar results for the neighboring isotone 42 Ca. [ABSTRACT FROM AUTHOR]

Measured and modeled Ca and Ti isotopic fractionation effects in a diverse suite of refractory inclusions are used to understand processes of condensation in the solar protoplanetary disk where they and their precursor materials formed. This coordinated approach reveals largely decoupled isotopic signatures and implies that few, if any, of the studied inclusions can be considered primary condensates. All studied inclusions are enriched in light Ca isotopes (∼−0.2 to − 2.8 ‰ / amu ), but only two show correspondingly light Ti isotopes. Studied inclusions exhibit both heavy and light Ti isotope enrichments (∼0.3 to − 0.4 ‰ / amu ). These refractory element isotopic signatures, therefore, suggest admixture and reprocessing of earlier formed materials with distinct condensation histories. Along with coordinated measurements of 50 Ti isotopic anomalies, which span a range from ∼0 to ∼40 epsilon-unit excesses, the comparison of measured and modeled fractionation of Ca and Ti isotopes provides a powerful approach to understanding primitive nebular processes and environments in the protoplanetary disk. Remarkable evidence for Ca isotopic zoning within a typical Type B1 inclusion exemplifies the potential record of the earliest solar nebula that is likely lost and/or overprinted in the isotopic compositions of more volatile elements (e.g., Mg, Si, and O) by later modification processes. [ABSTRACT FROM AUTHOR]

Northwest Africa (NWA) 7325 is an ungrouped achondrite that has recently been recognized as a sample of ancient differentiated crust from either Mercury or a previously unknown asteroid. In this work we augment data from previous investigations on petrography and mineral compositions, mid-IR spectroscopy, and oxygen isotope compositions of NWA 7325, and add constraints from Cr and Ti isotope compositions on the provenance of its parent body. In addition, we identify and discuss notable similarities between NWA 7325 and clasts of a rare xenolithic lithology found in polymict ureilites. NWA 7325 has a medium grained, protogranular to poikilitic texture, and consists of 10–15 vol.% Mg-rich olivine (Fo 98), 25–30 vol.% diopside (Wo 45, Mg# 98), 55–60 vol.% Ca-rich plagioclase (An 90), and trace Cr-rich sulfide and Fe,Ni metal. We interpret this meteorite to be a cumulate that crystallized at ⩾1200 °C and very low oxygen fugacity (similar to the most reduced ureilites) from a refractory, incompatible element-depleted melt. Modeling of trace elements in plagioclase suggests that this melt formed by fractional melting or multi-stage igneous evolution. A subsequent event (likely impact) resulted in plagioclase being substantially remelted, reacting with a small amount of pyroxene, and recrystallizing with a distinctive texture. The bulk oxygen isotope composition of NWA 7325 plots in the range of ureilites on the CCAM line, and also on a mass-dependent fractionation line extended from acapulcoites. The ε 54 Cr and ε 50 Ti values of NWA 7325 exhibit deficits relative to terrestrial composition, as do ordinary chondrites and most achondrites. Its ε 54 Cr value is distinct from that of any analyzed ureilite, but is not resolved from that of acapulcoites (as represented by Acapulco). In terms of all these properties, NWA 7325 is unlike any known achondrite. However, a rare population of clasts found in polymict ureilites (“the magnesian anorthitic lithology”) are strikingly similar to NWA 7325 in mineralogy and mineral compositions, oxygen isotope compositions, and internal textures in plagioclase. These clasts are probably xenolithic in polymict ureilites, and could be pieces of NWA 7325-like meteorites. Using constraints from chromium, titanium and oxygen isotopes, we discuss two possible models for the provenance of the NWA 7325 parent body: (1) accretion in the inner solar system from a reservoir similar to that of acapulcoites in Δ 17 O, ε 54 Cr and ε 50 Ti; or (2) early (<1 Ma after CAI formation) accretion in the outer solar system (beyond the snow line), before 54 Cr and 50 Ti anomalies were introduced to this region of the solar system. The mid-IR emission spectrum of NWA 7325 obtained in this work matches its modal mineralogy, and so can be compared with spectra of new meteorites or asteroids/planets to help identify similar materials and/or the parent body of NWA 7325. [ABSTRACT FROM AUTHOR]

A γ-spectroscopy study to search for chirality in 193Tl was conducted. Three negative-parity bands with close excitation energies and almost equal B(M1)/B(E2) values were identified. These bands were associated with the same πh9=2 ⊗vi13=2² configuration which is suitable for chiral symmetry. Analysis of the properties of these bands suggested that one or two chiral systems are formed in 193Tl. [ABSTRACT FROM AUTHOR]

Titanium isotopic compositions have been used to elucidate geochemical and cosmochemical processes. Until now, no Ti isotopic reference material has been reported worldwide, which imposes restriction upon analytical method establishment and laboratory quality control. In this paper, a newly prepared Ti isotopic standard solution is introduced. Ti element standard solution offered by the Alfa Company from U.S.A. was chosen as the starting material, based on the comparison of Ti isotopic measurement results of 3 commercially available Ti element standard solutions. The preparation of the new standard solution was strictly followed using the stipulation on reference material of the metrological technical standard of state, including homogeneity and stability tests, and certification analyses. 150 bottles of the solution were prepared, among which 15 bottles were selected randomly for homogeneity test and no detectable heterogeneity was found by F test. The stability inspection through 30 months indicated no significant changes on δTi values. The certified values and uncertainty at the 95% confidence level were shown to be: δ50Ti=-2.23‰±0.14‰, δ49Ti=-1.67‰±0.09‰,δ48Ti=-1.13‰±0.06‰ andδ47Ti=-0.57‰±0.05‰. This newly certified standard solution can be used to calibrate instruments and verify analytical quality in Ti isotope measurements, and compare inter-laboratory data.

We present here analyses of mass-independent effects in the Ti isotope ratios of 17 coarse-grained (compact Type A and Type B) calcium–aluminum-rich inclusions (CAIs) from the Allende CV3 chondrite utilizing a method developed for rapid measurement of Ti isotopes by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS). Based on the analyses of the synthetic CMAS glasses doped with varying amounts of Ca, Cr and V, an empirical scheme for correction of potential isobaric interferences and matrix effects was developed. Using this scheme, mass-independent variations of the Ti isotope ratios 46 Ti/ 47 Ti, 48 Ti/ 47 Ti and 50 Ti/ 47 Ti were measured with external reproducibilities (2SD) of ± 0.4, ± 0.5, and ± 1.8 for ε 46 Ti, ε 48 Ti, and ε 50 Ti, respectively, based on repeat measurements of standard glasses. The Ti isotope compositions of the 17 Allende refractory inclusions analyzed here show that most of these CAIs are “normal” with limited variation in their mass-independent Ti isotope composition. One CAI (designated as CMS-1) has a significantly larger mass-independent ε 50 Ti anomaly and is identified as having Fractionation and Unidentified Nuclear (FUN) effects. The limited range in the Ti isotope compositions of normal CAIs (ε 50 Ti excesses ranging from 2.9 to 11.4) suggests that they originated from a nebular reservoir that was relatively well-mixed, although not completely homogenized (at the level of precision of the analyses reported here), in its isotopic composition. The distinctive isotopic composition of the FUN CAI CMS-1 indicates that it formed from a reservoir in the protoplanetary disk that was spatially or temporally distinct from that from which the normal CAIs were formed. [ABSTRACT FROM AUTHOR]

PLACs (platy hibonite crystals) and related hibonite-rich calcium-, aluminum-rich inclusions (CAIs; hereafter collectively referred to as PLAC-like CAIs) have the largest nucleosynthetic isotope anomalies of all materials believed to have formed in the solar system. Most PLAC-like CAIs have low inferred initial 26 Al/ 27 Al ratios and could have formed prior to injection or widespread distribution of 26 Al in the solar nebula. In this study, we report 26 Al– 26 Mg systematics combined with oxygen, calcium, and titanium isotopic compositions for a large number of newly separated PLAC-like CAIs from the Murchison CM2 chondrite (32 CAIs studied for oxygen, 26 of these also for 26 Al– 26 Mg, calcium and titanium). Our results confirm (1) the large range of nucleosynthetic anomalies in 50 Ti and 48 Ca (our data range from −70‰ to +170‰ and −60‰ to +80‰, respectively), (2) the substantial range of Δ 17 O values (−28‰ to −17‰, with Δ 17 O = δ 17 O − 0.52 × δ 18 O), and (3) general 26 Al-depletion in PLAC-like CAIs. The multielement approach reveals a relationship between Δ 17 O and the degree of variability in 50 Ti and 48 Ca: PLAC-like CAIs with the highest Δ 17 O (∼−17‰) show large positive and negative 50 Ti and 48 Ca anomalies, while those with the lowest Δ 17 O (∼−28‰) have small to no anomalies in 50 Ti and 48 Ca. These observations could suggest a physical link between anomalous 48 Ca and 50 Ti carriers and an 16 O-poor reservoir. We suggest that the solar nebula was isotopically heterogeneous shortly after collapse of the protosolar molecular cloud, and that the primordial dust reservoir, in which anomalous carrier phases were heterogeneously distributed, was 16 O-poor (Δ 17 O ⩾ −17‰) relative to the primordial gaseous (CO + H 2 O) reservoir (Δ 17 O < −35‰). However, other models such as CO self-shielding in the protoplanetary disk are also considered to explain the link between oxygen and calcium and titanium isotopes in PLAC-like CAIs. [ABSTRACT FROM AUTHOR]

We present titanium stable isotope measurements of terrestrial magmatic samples and lunar mare basalts with the aims of constraining the composition of the lunar and terrestrial mantles and evaluating the potential of Ti stable isotopes for understanding magmatic processes. Relative to the OL–Ti isotope standard, the δ 49 Ti values of terrestrial samples vary from −0.05 to +0.55‰, whereas those of lunar mare basalts vary from −0.01 to +0.03‰ (the precisions of the double spike Ti isotope measurements are ca. ±0.02‰ at 95% confidence). The Ti stable isotope compositions of differentiated terrestrial magmas define a well-defined positive correlation with SiO 2 content, which appears to result from the fractional crystallisation of Ti-bearing oxides with an inferred isotope fractionation factor of Δ Ti oxide–melt 49 = − 0.23 ‰ × 10 6 / T 2 . Primitive terrestrial basalts show no resolvable Ti isotope variations and display similar values to mantle-derived samples (peridotite and serpentinites), indicating that partial melting does not fractionate Ti stable isotopes and that the Earth's mantle has a homogeneous δ 49 Ti composition of +0.005 ± 0.005 (95% c.i., n = 29 ). Eclogites also display similar Ti stable isotope compositions, suggesting that Ti is immobile during dehydration of subducted oceanic lithosphere. Lunar basalts have variable δ 49 Ti values; low-Ti mare basalts have δ 49 Ti values similar to that of the bulk silicate Earth (BSE) while high-Ti lunar basalts display small enrichment in the heavy Ti isotopes. This is best interpreted in terms of source heterogeneity resulting from Ti stable isotope fractionation associated with ilmenite–melt equilibrium during the generation of the mantle source of high-Ti lunar mare basalts. The similarity in δ 49 Ti between terrestrial samples and low-Ti lunar basalts provides strong evidence that the Earth and Moon have identical stable Ti isotope compositions. [ABSTRACT FROM AUTHOR]

The phase formation, texture, and photocatalytic activity of synthesized oxide nanocomposites of titanium(IV) and cobalt(II) have been studied in relation to the cobalt content and temperature of heat treatment. The high photocatalytic activity of optimum compositions has been recorded within the spectral range of visible light with λ ≥ 670 nm. [ABSTRACT FROM AUTHOR]