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The large Mo isotopic fractionations between diferent geological reservoirs make this isotopic system a potentially useful tool for constraining the origins of magmatism. However, the efect of magmatic diferentiation on Mo isotopes is still controversial. In this study, we obtained Mo isotope data for the Panzhihua gabbroic intrusion (i.e., including mineral separates of clinopyroxene, plagioclase, magnetite, and ilmenite). The whole-rock samples and mineral separates exhibit large Mo isotopic fractionations with δ98/95Mo values as follows: magnetite (–0.73‰ to –0.32‰) < clinopyroxene (–0.32‰ to –0.10‰) < ilmenite (0.06‰ to 0.36‰) < plagioclase (0.33‰ to 0.83‰). Iron-Ti oxides have Mo contents that are one order of magnitude higher than those of clinopyroxene and plagioclase. Mass balance calculations based on Mo isotopes and contents are consistent with an accumulated origin for the Panzhihua intrusion. Rayleigh fractionation modeling shows that the removal of magnetite and ilmenite results in significant Mo isotopic fractionation in the residual magma. Due to the low Mo contents of clinopyroxene and plagioclase, Mo isotopes are not significantly fractionated by the removal of these minerals. Therefore, our study highlights that fractionation of Fe-Ti oxides can cause considerable Mo isotopic fractionation; consequently, caution is needed when using Mo isotopes to infer magma origins. [ABSTRACT FROM AUTHOR]

After decades of development of the vanadium titanomagnetite (VTM) ore in the Panzhihua district changes have taken place to the ore characteristics. In addition, preliminary research carried out in this area mainly focused on the separation and extraction of iron resources and lacked a systematic research focus on the process mineralogy of ilmenite, resulting in a low grade and yield of the separated ilmenite. Therefore, the present study investigates the compositions, textures, element distributions, and particle size characteristics of VTM ores in Panzhihua were studied via mineral dissociation analysis (MLA), electron microscope–microprobe analysis (EPMA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that the chemical and mineral compositions of the VTM ore samples were basically stable. However, the size of the embedded particles of ilmenite and titanomagnetite was smaller than that reported previously. In addition, the olivine content was found to have significantly increased, and a large number of altered minerals (such as chlorite and sphene) were also present, as a result of which the degrees of monomer dissociation of ilmenite and titanomagnetite reached 85% when the fraction of particles with size in the range of 0.04–0.15 mm was 75%. [ABSTRACT FROM AUTHOR]

Eclogites from the Guanshan and Yangkou areas of the Sulu orogen consist of garnet, omphacite, phengite, amphibole, quartz/coesite, rutile, and ilmenite. Garnet exhibits weak compositional zoning where Xgr decreases from the core to the mantle and then increases towards the rim, coupled with an increase in Xpy from the core to the mantle and then decrease towards the rim. Phase equilibria modelling with pseudosections calculated using THERMOCALC in the NCKFMASHTO system for the Guanshan and Yangkou eclogites records two stages of metamorphism: (I) prograde associated with quick subduction (Stage-I) and (II) retrograde associated with quick exhumation (Stage-II). Stage-I is recorded in the core-mantle zoning of garnet and Si content in phengite in the Guanshan and Yangkou eclogites with a mineral assemblage of Grt-Omp-Amp-Phg-Qtz-Rt ± Lws, and the P-T conditions are constrained at 22–26 kbar and 600–615 °C in Guanshan, while 24–26 kbar and 595–600 °C in Yangkou. The peak P-T conditions (Pmax = 33 kbar; T = 685 °C) of Guanshan eclogites are revealed by the maximum Si content in phengite and the minimum Xgr in the garnet mantle with the mineral assemblage of Grt-Omp-Phg-Coe-Rt ± Lws. The value of Pmax suggests that the subduction depth of the Guanshan eclogites exceeds 110 km. Stage-II is recorded in the mantle-rim zoning of garnet, and its P-T conditions are estimated to be 12–15 kbar and 780–820 °C for the Guanshan eclogites reflected by the assemblage of Grt-Omp-Amp-Pl-LL-Qtz-Rt ± ilm, and 13–14 kbar and 770–790 °C for the Yangkou eclogites by the assemblage of Grt-Omp-Amp-Pl-LL-Qtz-Rt. The two stages of metamorphism in the study areas are overall consistent with the regional metamorphic events, from ultra-high-pressure eclogite facies, through high pressure eclogite facies, to amphibole eclogite facies, with the ages of 245, 227 and 195 Ma, respectively. [ABSTRACT FROM AUTHOR]

Orientated ilmenite inclusions have been discovered in amphibole of hornblendite from the Zhujiapu area, Dabie ultra-high-pressure (UHP) metamorphic terrane, China. In order to characterize the crystallographic orientation relationships between ilmenite inclusions and amphibole host and reconstruct the mechanism of their formation, we present an electron backscatter diffraction (EBSD) analysis combined with energy dispersive spectroscopy (EDS) analysis and electron microprobe analysis (EPMA) for ilmenite inclusions and amphibole host. The inclusions can be subdivided into four groups: (1) 60.2% of ilmenites have the crystallographic orientation {0001}Ilm // {100}Amp, (1010)Ilm // {010}Amp, [112̅0]Ilm // <001>Amp and [112̅0]Ilm // <012>Amp. (2) 16.5% of Ilmenites have <0001> Ilm // <001>Amp, (101̅0)Ilm // {010}Amp, (112̅0)Ilm // {100}Amp and [3̅031]Ilm // <012>Amp. (3) 13.8% of Ilmenites have <0001> Ilm // <012>Amp, (112̅0)Ilm // {100}Amp and [3̅031]Ilm // <001>Amp. (4) 9.5% of Ilmenites have <0001> Ilm // [1̅12]Amp, (101̅0)Ilm // {201}Amp, [112̅0]Ilm // [1̅12]Amp and Ilm [1121] // <010>Amp. By comparing the lattice relationship between ilmenite inclusions and amphibole hosts, it is shown that the frequency of the ilmenite inclusions in different groups is related to the lattice coherency and oxygen packing. Group-1 of the ilmenite inclusions was most likely be formed via a solid-state exsolution process by cooling of the hornblendite after the intrusion was emplaced. The other three groups of ilmenite inclusions were probably formed via reduction reaction in an open system. The formation temperature of the ilmenite inclusions is estimated by using the TiO2 solubility geothermeter in amphibole. The minimum formation temperature of the ilmenite inclusions is about 1025 °C, and the maximum formation temperature of the ilmenite inclusions is about 1126 °C. [ABSTRACT FROM AUTHOR]

China is rich in titanium resources, which accounts for more than 35% of the world. But, until today, the industrial TiO2 recovery for ilmenite ore is slightly higher than 30% in the current pulsating high-gradient magnetic separation-flotation process (HGMS) so that a large amount of ilmenite value were lost in tailings. A centrifugal HGMS (CHGMS) method was introduced and a novel HGMS-flotation process combining the method was investigated to achieve an enhanced separation for Panzhihua ilmenite tailings in China. The results of this investigation indicate that this new process achieved a superior separation performance to the current one and produced a qualified ilmenite concentrate assaying 46.62% TiO2 at a significantly enhanced recovery reaching 40.42%. In the new process, the CHGMS separator concentrated ilmenites at high selectivity and produced a high-grade ilmenite concentrate fed to flotation cleaning process, which significantly benefited the enhanced separation for the ilmenite tailings. It was concluded that this new HGMS-flotation process is prospective in improving the separation performance for ilmenite from tailings. [ABSTRACT FROM AUTHOR]

The study presents investigations on an interesting co-mineralization phenomenon (placer ilmenite and ion-adsorption REEs) related to weathering of intermediate igneous rocks in South China. In order to delineate the origin of such co-mineralization from source to sink, a genetic model is proposed as shown in below figure. It demonstrated that the occurrence of placer ilmenite and iREEs co-mineralization depends principally on the specific nature of some intermediate igneous rocks that contain both rich Ti-bearing and REEs-bearing accessory minerals. Strong weathering, in one way, gave rise to residual accumulation of ilmenite at upper horizons, and in the other way, generated secondary enrichment of iREEs through eluviation-illuviation at lower horizons. These two enrichment processes happened independently, and generated mineralization effect at different regolith positions. It caused the ore horizons of placer ilmenite and iREEs developed symbiotically but show somewhat dislocation within the regolith. [Display omitted] • Ore-bearing regolith profiles with placer ilmenite and iREEs co-mineralization in South China were investigated. • A genetic model is proposed to understand the co-mineralization of placer ilmenite and iREEs regulated by weathering of various intermediate igneous rocks. • The importance of comprehensive evaluation is emphasized in future exploration and resource utilization of weathering deposits. The placer type ilmenite and ion-adsorption type rare earth elements (iREEs) deposits are two important weathering-related mineral resources in South China, a global supplier of Ti and REEs critical metals. It was believed that these two deposits are not linked to each other because of their different ore-forming conditions and mechanisms. However, many studies have reported that parts of placer ilmenite deposits, especially for those developed by weathering of intermediate igneous rocks, also contain abundant iREEs resources that have not been noticed before. To elucidate the origin of this interesting co-mineralization phenomenon that is of both scientific and economic significance, we conducted a comparative study of three deposits, including Qinghu (QH), Madi (MD), and Tangcun (TC) from Guangxi Province in the western segment of South China. Investigations showed that although the ore-forming parent rocks from the QH, MD, and TC deposits are intermediate igneous rocks, their corresponding regolith profiles are significantly different in their mineralization characteristics. The diorite-derived QH and tonalite-derived MD deposits showed co-mineralization of ilmenite with iREEs, whereas the pyroxene diorite-derived TC deposit only showed independent mineralization of ilmenite. Evidences from systematic mineralogical and geochemical examinations indicated that the occurrence of ilmenite and iREEs co-mineralization, besides the impact of weathering, may principally regulated by the nature of accessory mineral assemblage in the parent rocks. Specifically, both Ti-bearing (ilmenite, anatase) and REEs-bearing (apatite, titanite) accessory minerals were largely identified in the QH diorite and MD tonalite. Analysis of degree of saprolitization (DOS) and weathering index of granite (WIG) revealed that they have experienced strong weathering, which gave rise to residual accumulation of Ti-bearing minerals (mainly ilmenite) at upper horizons of the regolith profiles, and simultaneously, secondary enrichment of iREEs by eluviation-illuviation process at lower horizons. It explained the ore horizons of placer ilmenite and iREEs developed symbiotically but show somewhat dislocation within the regolith. In contrast, the TC pyroxene diorite was found to be rich only in Ti-bearing minerals but poor in REEs-bearing minerals. It is conductive to develop weathering mineralization of ilmenite rather than iREEs in terms of ore source. Also, there is rich iron oxides and hydroxides in the pyroxene diorite-derived regolith, which might has inhibited REEs eluviation-illuviation and act as the other reason for absence of iREEs mineralization in the TC profile. This study not only provides a genetic model to understand the co-mineralization of placer ilmenite and iREEs ores developed by weathering of intermediate igneous rocks, but also highlights the importance of a comprehensive evaluation in future prior to exploration and resource utilization. [ABSTRACT FROM AUTHOR]

• A review the public sources for zirconium and titanium production and resources. • A discussion of factors affecting zirconium and titanium resource availability. • A discussion of the complexity of titanium and zirconium feedstocks. • A thorough history of the titanium and zirconium industry. • An overview of deposit geology and ilmenite alteration terminology. • An overview of logistics, mining and processing techniques. • An examination of each of the major co-products of titanium and zirconium extraction. Recent zircon supply disruptions and the increasing demand for TiO 2 in pigments has focused attention on the adequacy of known and anticipated resources, and the ability of current suppliers to meet future demand. Additionally, there is now a greater focus on the environmental impact of sulfate- and chloride-route pigment production, especially in China. These methods require different types of titanium feedstocks, each having different levels of availability. Despite investigation by various government groups, consultants, and scholars, there remain significant discrepancies in both production and resource assessments. The few publically available studies do not take into account these complexities. Here we review the public sources for information on zirconium and titanium production and resources using Australia as a case study, factors affecting resource availability, the complexity of titanium and zirconium feedstocks, their suitability for end-uses, their commercial properties, supply drivers. We also provide a thorough history of the titanium and zirconium industry, an overview of deposit geology & ilmenite alteration terminology, logistics, mining and processing techniques, as well as an examination of each of the major co-products of titanium and zirconium extraction. [ABSTRACT FROM AUTHOR]

[Display omitted] • CSDs for Fe-Ti oxides are used to examine the formation of Fe-Ti oxide ores. • Fe-Ti oxide ores in the Bijigou intrusion are formed by in situ crystallization. • Dissociation of H 2 O from interstitial liquid can increase oxygen fugacity of melts. • Ion diffusion results in a Cr-increase of magnetite toward the top of each unit. The formation of Fe-Ti oxide ore bodies in layered intrusions is attributed to in situ crystallization of basaltic magmas or accumulation after crystal settling regardless of their thicknesses and occurrences in the intrusion. These two key processes are difficult to be distinguished in terms of chemical compositions of minerals or cumulates. However, the crystal size distributions (CSDs) of Fe-Ti oxides in the rocks can be remarkably distinct in these two processes. In this study, we collected samples from a drill core profile across the major Fe-Ti oxide-rich segment of the Bijigou intrusion, a large and differentiated layered intrusion in Central China, and carried out a detailed study on the CSDs and in situ major and trace elements of magnetite and ilmenite to examine how Fe-Ti oxides are accumulated to form Fe-Ti oxide ore bodies in the intrusion. The major Fe-Ti oxide-rich segment of the intrusion consists of, from the base upward, a Fe-Ti oxide ore layer (∼80 m), a troctolite unit (∼105 m), an oxide gabbro unit (∼153 m) and an apatite-oxide gabbronorite unit (∼165 m). Large grains of magnetite and ilmenite in the Fe-Ti oxide ore layer show logarithmic-linear CSD curves, similar to those yielded by in situ crystallization of Fe-Ti oxides. The modes of Fe-Ti oxides in the oxide gabbro unit and apatite-oxide gabbronorite unit fluctuate along the profile, which cannot be attributed to accumulation after crystal settling. In addition, the magnetite of the Fe-Ti oxide ore layer, oxide gabbro unit and apatite-oxide gabbronorite unit shows a gentle increase trend of Cr concentration from the base upward in each unit, inconsistent with the trend for an accumulation after crystal settling. The magnetite grains enclosed within silicates have similar compositions to those interstitial to silicates, indicating that they all crystallized from similarly interstitial Fe-rich melt. The in situ crystallization of Fe-Ti oxides is likely triggered by increasing oxygen fugacity due to dissociation of H 2 O in highly evolved interstitial liquid that was expelled from underlying crystal mush. The crystallization of low-Cr magnetite at the base of each unit is attributed to suppressed eddy currents by dramatic increase of latent heat of crystallization in the magmas at the base. The eddy currents may gradually become efficient toward the top of the magmas due to rapid dissipation of latent heat of crystallization in the magmas, leading to crystallization of high-Cr magnetite by ion diffusion on the top of each unit. This study also demonstrates that analysis of CSDs for Fe-Ti oxides is applicable to examine the accumulation mechanism of Fe-Ti oxide ore bodies in layered intrusions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magmatic oxygen fugacity decreases during magma evolution. • Magmatic source originated from melting of juvenile mafic lower crust and ancient crustal components. • Magma undergone strongly fractionated crystallization and intense melt/fluid interaction. • Decline in oxygen fugacity, enrichment of F element, fractionated crystallization, and melt/fluid interaction of granites are important factors for mineralization. The Maodeng deposit, located in Xilinhot, Inner Mongolia, is a typical Mo-Bi-Sn-Cu deposit in the southern segment of the Great Xing'an Range. It is genetically related to the Alubaogeshan granitic complex, which is composed of porphyritic monzogranite (G1), granite porphyry (G2), and alkali feldspar granite (G3). However, the comparison of physical–chemical condition and magmatic evolution of different lithofacies has not been conducted. We present in-situ major-trace elements and Sm-Nd isotopes of apatite, in-situ major-trace elements of plagioclase, as well as in-situ major elements of magnetite and ilmenite from the G1 and G2, with the goal of discussing magma genesis and its constraints on mineralization. The apatites from the two granites are characterized by relative enrichment in F and light rare earth elements (LREEs) but depletion in Cl, S, and heavy rare earth elements (HREEs), as well as obviously negative Eu, Sr, Nb, Ba, Zr, and Hf and positive Y anomalies, indicating that the two granites have similar sources and experienced significant crystallization differentiation. When compared to G1, apatites from G2 exhibit more significant Eu, Sr, and Y anomalies, as well as lower (La/Sm) N and (La/Yb) N ratios, likely due to intensive crystallization of plagioclase and exsolution of Cl-bearing magmatic fluids. The presence of core-rim zoning patterns with BSE-bright and BSE-grey domains in some G2 apatite crystals indicates extensive hydrothermal alteration. The plagioclases within G1 belong to andesine–oligoclase series corresponding to magmatic water contents of 1.4 to 1.9 wt%, and those in G2 belong to oligoclase–albite series with calculated magmatic water contents of 2.1 to 2.2 wt%. The plagioclase crystals from G1 are characterized by prominently positive Eu and moderately positive Sr and Ba anomalies, with crystals from G2 showing strongly negative Eu, Ba and Sr anomalies, indicating more significant fractionating plagioclase and apatite in G2 than G1. The magnetite compositions are distinguished by high FeO, TiO 2 , and MnO contents. Ilmenite usually cuts and dissolves magnetite, and contains a lot of FeO, TiO 2 , MnO, and Nb 2 O 3. The magnetite and ilmenite from the two granites have a coherent negative correlation between Ti and Fe3+ but a consistent positive correlation between Ti and Fe2+, implying that they crystallized from a homologous silicate magma. During the crystallization of apatites, magmatic oxygen fugacities of the two granites were slightly above the ΔNNO buffer line. However, these were near the FMQ buffer line when the magnetite and ilmenite were in equilibrium at temperatures ranging from 561 to 666 °C, indicating a decreasing trend in oxygen fugacity during magma evolution. The apatites of both G1 and G2 have high ε Nd (t) values (+0.59 to + 1.94 and − 2.13 to + 0.42, respectively), and young two-stage Nd model ages (t DM2 = 775–884 Ma and 897–1106 Ma, respectively), suggesting the predominant origin of these rocks by the partial melting of a juvenile mafic lower crust and "old" pre-existing crustal components, having a substantial proportion of continental crust for G2. The decline in oxygen fugacity, enrichment of F element, highly crystallization differentiation, intense melt/fluid interaction, and the strong hydrothermal alteration for the ore-related granite could contribute to the formation of the Maodeng deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Saima alkaline complex was product of partial melting of enriched subcontinental lithospheric mantle and emplaced at ca. 230 Ma. • Fractional crystallization of Nb-poor minerals facilitates enrichment of Nb in the residual melts. • Hydrothermal activity remobilized Nb from altered Nb-rich rutile to form pyrochlore. The Triassic Saima alkaline complex on the northern margin of the North China Craton (NCC) is composed mainly of nepheline syenite, along with some nepheline syenite pegmatite and mineralized nepheline syenite, and it contains REEs (bastnäsite) + Nb (Nb-rich rutile and pyrochlore) and Zr (zircon) mineralization. However, the effects of magmatic and hydrothermal processes on Nb enrichment and mineralization remain unclear. Thus, we conducted a comprehensive study of the Nb mineralization in the Saima alkaline complex. Biotite in the altered nepheline syenite and pegmatite has inverse isochron 40Ar/39Ar ages of 234.30 ± 6.30 and 230.08 ± 2.75 Ma, respectively. Together with the close spatial relationship and the reported ages of the aegirine nepheline syenite associated with Nb mineralization, we propose that the altered and mineralized nepheline syenite and pegmatite were formed at the same time. In addition, clinopyroxene and biotite compositional trends, an increase in the proportion of hydrous minerals including natrolite, hydromuscovite, and arfvedsonite, and the growth of K-feldspar suggest that the magma evolved from nepheline syenite to mineralized nepheline syenite and nepheline syenite pegmatite. The altered nepheline syenites yield low initial 87Sr/86Sr ratios (0.709625–0.712132) and negative ε Nd (t) values (−15.32 to −14.15), consistent with previous studies of fresh samples, suggesting that the Saima alkaline rocks were produced by the partial melting of metasomatized lithospheric mantle. The early-crystallized magmatic Nb-rich titanite and rutile in the nepheline syenite and pegmatite indicates an initial Nb-rich parent magma, and fractional crystallization of Nb-poor minerals increased the Nb content of the residual melts. The crystallization of Nb minerals (pyrochlore) and Nb-rich minerals (altered rutile, titanite, and ilmenite) may have been the result of metasomatism by post-magmatic Na- and F-rich fluids, indicating the redistribution and precipitation of Nb. Thus, we conclude that Nb was enriched through magmatic processes, and the Nb mineralization was related mainly to hydrothermal activity. [ABSTRACT FROM AUTHOR]

In situ LA–ICP–MS trace elemental analysis has been applied to magnetite and ilmenite of the Taihe layered intrusion, Emeishan large igneous province, SW China, in order to understand better fractionation processes of magma and origin of Fe–Ti–V oxide ore deposits. The periodic reversals in Mg, Ti, Mn in magnetite and Mg, Sc in ilmenite are found in the Middle Zone of the intrusion and agree with fractionation trends as recorded by olivine (Fo), plagioclase (An) and clinopyroxene (Mg#) compositions. These suggest the Taihe intrusion formed from open magma chamber processes in a magma conduit with multiple replenishments of more primitive magmas. The V and Cr of magnetite are well correlated with V and Cr of clinopyroxene indicating that they became liquidus phases almost simultaneously at an early stage of magma evolution. Ilmenite from the Middle and Upper Zones shows variable Cr, Ni, V, Mg, Nb, Ta and Sc contents indicating that ilmenite at some stratigraphic levels crystallized slightly earlier than magnetite and clinopyroxene. The early crystallization of magnetite and ilmenite is the result of the high FeO t and TiO 2 contents in the parental magma. The ilmenite crystallization before magnetite in the Middle and Upper Zones can be attributed to higher TiO 2 content of the magma due to the remelting of pre-existing ilmenite in a middle-level magma chamber. Compared to the coeval high-Ti basalts, the relatively low Zr, Hf, Nb and Ta contents in both magnetite and ilmenite throughout the Taihe intrusion indicate that they crystallized from Fe–Ti–(P)-rich silicate magmas. Positive correlations of Ti with Mg, Mn, Sc and Zr of magnetite, and Zr with Sc, Hf and Nb of ilmenite also suggest that magnetite and ilmenite crystallized continuously from the homogeneous silicate magma rather than an immiscible Fe-rich melt. Therefore, frequent replenishments of Fe–Ti–(P)-rich silicate magma and gravitational sorting and settling are crucial for the formation the massive and apatite-rich disseminated ores in the Lower and Middle Zones of the Taihe intrusion. [ABSTRACT FROM AUTHOR]

Origin of low δ 26 Mg basalts is a controversial subject and has been attributed to interaction of isotopically light carbonatitic melts derived from a subducted oceanic slab with the mantle (Yang et al., 2012), or alternatively, to accumulation of isotopically light ilmenite (FeTiO 3 ) in their mantle source (Sedaghatpour et al., 2013). To study the origin of low δ 26 Mg basalts and evaluate whether Mg isotope ratios of basalts can be used to trace deeply recycled carbon, high-precision major and trace element and Mg isotopic analyses on the Cenozoic alkaline and tholeiitic basalts from the South China Block (SCB), eastern China have been carried out in this study. The basalts show light Mg isotopic compositions, with δ 26 Mg ranging from −0.60 to −0.35. The relatively low TiO 2 contents (<2.7 wt.%) of our basalts, roughly positive correlations between δ 26 Mg and Ti/Ti ∗ and their constant Nb/Ta ratios (16.4–20) irrespective of variable TiO 2 contents indicate no significant amounts of isotopically light ilmenite accumulation in their mantle source. Notably, the basalts display negative correlations between δ 26 Mg and the amounts of total alkalis (i.e., Na 2 O + K 2 O) and incompatible trace elements (e.g., Ti, La, Nd, Nb, Th) and trace element abundance ratios (e.g., Sm/Yb, Nb/Y). Generally, with decrease of δ 26 Mg values, their Hf/Hf ∗ and Ti/Ti ∗ ratios decrease, whereas Ca/Al and Zr/Hf ratios increase. These features are consistent with incongruent partial melting of an isotopically light carbonated mantle, suggesting that large variations in Mg isotope ratios occurred during partial melting of such carbonated mantle under high temperatures. The isotopically light carbonated mantle were probably formed by interaction of the mantle with low δ 26 Mg carbonatitic melts derived from the deeply subducted low δ 26 Mg carbonated eclogite transformed from carbonate-bearing oceanic crust during plate subduction. As only the Pacific slab has an influence on both the North China Block (NCB) and SCB, our results together with the study of Yang et al. (2012) demonstrate that the recycled carbonatitic melts might have originated from the stagnant Pacific slab beneath East Asia in the Cretaceous and Cenozoic and that a widespread carbonated upper mantle exists beneath eastern China, which may serve as the main source for the <110 Ma basalts in this area. Thus, our study demonstrates that Mg isotope ratios of basalts are a powerful tool to trace deeply recycled carbon. [ABSTRACT FROM AUTHOR]

The geological record of the Neoproterozoic to early Palaeozoic Proto-Tethyan Ocean in Southeast Asia is not clear. To better constrain the evolution of the Proto-Tethys, we present new geochronology, geochemistry, and petrology of the late Cambrian to Ordovician Pinghe pluton monzogranite from the Baoshan block, western Yunnan, southwest China. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of four zircon samples yield ages of 482–494 and 439–445 Ma for the pluton, interpreted as two episodes within one magmatic event accompanying the whole process of subduction–collision–orogeny between buoyant blocks and oceanic crust of the Proto-Tethys. The monzogranite belongs to the strong peraluminous, high-K, calc-alkaline series and shows characteristics of both I-type and S-type granitic rocks. It is characterized by extremely high Rb/Sr and Rb/Ba but low TiO2, MgO, FeOt, and CaO/Na2O ratios. The monzogranite is also moderately enriched in light rare earth elements (LREEs), depleted in heavy rare earth elements (HREEs), lacks HREE fractionation, and has strongly negative Eu (Eu/Eu* = 0.06–0.49), Ba, Nb, Ta, Sr, and Ti anomalies. Whole-rockεNd(t) andεHf(t) values range from −8.7 to −11.6 and −5.55 to −9.58, respectively. Nd and Hf two-stage model ages range from 1.66 to 2.06 Ga and 2.14 to 3.00 Ga, respectively, with variable radiogenic206Pb/204Pb(t)(16.547–18.705),207Pb/204Pb(t)(15.645–15.765), and208Pb/204Pb(t)(38.273–38.830). These signatures suggest that the monzogranite magma was derived from partial melting of heterogeneous metapelite, which was generated from Neoarchean to Palaeoproterozoic materials mixed with basaltic magma. The monzogranite magma underwent crystallization differentiation of plagioclase, K-feldspar, and ilmenite. Magmatism to form the Pinghe pluton occurred in a post-collisional setting. Based on the comparison of coeval granites throughout adjacent regions (e.g. Himalayan orogen, Lhasa Terrane, and parts of Gondwana supercontinent), we propose that the Baoshan block was derived from the northern Australian Proto-Tethyan Andean-type active continental margin of Gondwana and experienced subduction of the Proto-Tethyan oceanic crust and accretion of an outboard micro-continent. The Pinghe pluton could have formed when a subducting oceanic slab broke off during collision. [ABSTRACT FROM AUTHOR]

China's Chang'E-5 mission returned new samples from the Moon and has extended the eruption ages of lunar volcanism ca. 800 million years younger than previous determinations. This finding challenges our past perceptions of the lunar thermal and magmatic evolution and has attracted great attention. Since the lunar basalts show a wide compositional range, it is essential to classify them carefully in order to define their origin and evolution. However, whether the Chang'E-5 basalts are classified as high-Ti or low-Ti type remains debatable because the basalt clasts picked from the Chang'E-5 soil samples are so tiny that their bulk composition estimations involve large uncertainties. Instead of using bulk composition, this study employs Ti in olivine to track the crystallization sequence of the Chang'E-5 basalts and then to classify them. In the Chang'E-5 olivines, Ti contents first increase and then decrease with a continuous decrease of forsterite values. Such a compositional variation reveals a magma differentiation series from early ilmenite unsaturation to ilmenite saturation during the late stage. Furthermore, the TiO 2 content of the hypothesized parental magma that corresponds to the most primitive olivine is estimated to be ~4.4 wt%. These results confirm that the Chang'E-5 basalts originated from a low-Ti primary magma. This study shows that olivine can be used as a robust mineral indicator to distinguish between high-Ti and low-Ti mare basalts. • This study performed olivine minor element analyses on Chang'E-5 lunar basalts. • Ti in olivine reveals ilmenite crystallization later than olivine and clinopyroxene. • The Chang'E-5 basalts can be classified as low-Ti type of mare basalt. • Olivine has a great potential to illuminate lunar magmatic origin and evolution. [ABSTRACT FROM AUTHOR]

Detrital ilmenite and its altered minerals are common in sandstone-hosted U deposits in the northern Ordos Basin, north China. Petrographic observation, SEM-EDS, EMPA, and LA-MC-ICP-MS were utilized to characterize the spatial relationship between altered ilmenite and the U minerals, and to investigate the U enrichment mechanism and alteration processes of ilmenite. Ilmenite was completely or partially altered to leucoxene and anatase along its rim and crack in ore-bearing sandstone. Framboidal and cement pyrite of BSR and TSR origin were identified around altered ilmenite. Two U phases closely related to altered ilmenite contain Ti-coffinite (I) and coffinite (II). These data indicate that ilmenite alteration and the associated processes of U enrichment can be divided into two stages. Stage one involves U pre-enrichment and adsorption, with stage two involving U enrichment via TiO2 (leucoxene and anatase) catalytic reduction. Ilmenite was altered into porous leucoxene that can adsorb U as uraniferous leucoxene and Ti-coffinite (I) and framboidal pyrite directly by reactions with H2S, produced by sulfate-reducing bacteria during synsedimentary and early diagenesis stages. Altered ilmenite can enrich U in the form of coffinite (II) through a catalytic reduction reaction which is triggered by β and γ radiation produced by previously adsorbed U during the uplift of ore-bearing bed in the Late Cretaceous period. In addition, cement pyrite can also reduce U6+ into U4+ which deposits on its surface in the form of coffinite (II). These results demonstrate a new mechanism, mediated by adsorption and catalytic reduction, to enrich U in sandstone-hosted U deposits. [ABSTRACT FROM AUTHOR]

The article presents abstracts on geological topics which include tungsten mineralization processes in New Brunswick, Canada, gold deposits in Yunnan, China, and magnetite discovered in a metallogenic belt in Tibet.

Abstract: The Inner Mongolia Suture Zone (IMSZ, incorporating the Khondalite Belt) forms part of an accretionary orogen developed during the Paleoproterozoic collision between the Yinshan Block and Ordos Blocks within the North China Craton (NCC). The granulites within the IMSZ are characterized by high-temperature (HT) to ultrahigh-temperature (UHT) metamorphism with diagnostic mineral assemblages for UHT conditions preserved in some localities such as Tuguiwula and Wuchuan. We report here a new locality in Heling''er, located within the southern domain of the IMSZ where spinel–garnet–sillimanite-bearing granulites record UHT metamorphic conditions. The prograde assemblages occurring as inclusions in porphyroblastic minerals in these rocks include sillimanite+quartz+spinel, whereas coarse grained garnet+sillimanite+quartz+spinel+cordierite+plagioclase+K-feldspar+magnetite+ilmenite represent the peak assemblages. The retrograde stage is marked by orthopyroxene and cordierite rims developed on garnet and spinel. Biotite marks the final hydration stage of the high-grade metamorphism. Spinel and quartz occur in direct contact, with the spinel showing low Zn, Cr, and Fe3+. Application of Ti-in-zircon and ternary feldspar geothermometers yields temperatures up to ~940°C for the peak stage. Mineral phase equilibria modeling based on the bulk chemistry and mineral assemblages shows that the peak assemblage of garnet+plagioclase+spinel+cordierite+sillimanite+quartz+ilmenite+magnetite was stabilized at 1030°C at 6.5–7.5kbar, thus we infer a 940–1030°C temperature range for peak metamorphism in these rocks. The newly discovered UHT rocks in Heling''er, dated as 1.92Ga, together with the two previously reported UHT localities at Tuguiwula and Wuchuan, suggest that the Paleoproterozoic UHT metamorphism occurred on a regional scale within the IMSZ, probably in association with the subduction–accretion–collision tectonics and the incorporation of the NCC within the Columbia supercontinent. [Copyright &y& Elsevier]

Sn is generally the dominant form of tin in magnetite-series granites as shown by the presence of cassiterite or its incorporation into Ti-bearing minerals such as biotite and titanite. Little is known about the behavior of tin in magnetite. The Huashan granite is an oxidized tin granite in the Nanling Range, southern China, where it contains magnetite as the dominant Fe oxide mineral. It is included in biotite as an early phase and also as interstitial grains spatially associated with ilmenite, cassiterite, Sn-rich titanite (SnO up to 5.9 wt.%), fluorite and apatite. This association indicates that tin enrichment occurred during the late stage of magma crystallization. Ilmenite lamellae display a trellis structure consistent with features of the 'oxy-exsolution' process of Sn-bearing titanomagnetite precursor. Micro-inclusions of cassiterite (<1 μm in size) are found only within ilmenite lamellae. This suggests that magnetite with cassiterite inclusions is likely an indicator mineral of oxidized tin granites. Although rare in nature, Sn-bearing magnetite from weathered granites where concentrated in stream sediments, may serve as a strategic tracer for tin exploration in granite districts and in placer deposits, in general. [ABSTRACT FROM AUTHOR]

Spongy textures are observed in mantle peridotite xenoliths hosted in Cenozoic kamafugites from the Western Qinling, central China. These textures are mainly developed in clinopyroxenes and spinels, and occur as spongy rims consisting of low-Na clinopyroxene, ilmenite, and bubbles, enclosing nonspongy cores. The ilmenites and bubbles exhibit shapes and sizes that vary with the width of the spongy rims. The spongy-textured minerals preserve primary shapes and well-defined grain boundaries and do not show apparent interaction with contact minerals or observed melts except the subsequent melts forming melt pockets. The xenocrysts display reactive zoning textures with host magmas rather than spongy textures. Compositionally, the spongy rims are enriched in Ca, Ti, and most trace elements, have high Cr#, and are depleted in Na, Al, Fe, Al, and Al/Al compared with the cores. These observations suggest that melts/host magmas did not play any significant role in the formation of the spongy textures. We therefore propose that spongy-textured clinopyroxenes and spinels in Western Qinling peridotite xenoliths developed from a decompression-induced partial melting event prior to formation of melt pockets and xenolith entrainment in host magmas. [ABSTRACT FROM AUTHOR]

Abstract: The main utilization mode of titano-magnetite was firstly separating titano-magnetite by low intensity magnetic separation, then concentrating ilmenite from magnetic separation tailings. Magnetic separation tailings mainly contained ilmenite, but there was still a small quantity of titano-magnetite. Magnetic agglomeration of titanomagnetite occured because of existentence of remanence and pre-flotation grinding. It was found that titanomagnetite presented more optimal floatability than ilmenite. Therefore some gangues wrapped by titano-magnetite went into the floatation concentrate. In a word, titano-magnetite had negative effect on ilmenite floatation by decreasing grade and recovery of concentrate and increasing reagent consumption. The pre-removal of residual titano-magnetite before cleaning ilmenite from magnetic separation tailings by floatation was essential. [Copyright &y& Elsevier]

Abstract: The effects of mechanical activation on the hydrochloric acid leaching performance of Panxi ilmenite from Sichuan province of China were investigated. The unactivated and mechanically activated ilmenites were characterized using X-ray diffraction (XRD), particle size analysis, and Scanning Electron Microscope (SEM) techniques to determine the structural changes of Panxi ilmenite during the mechanical activation process. The results show that mechanical activation elevated the calcium, magnesium and iron extraction of Panxi ilmenite irreversibly which mostly attributes to the lattice disorder of Panxi ilmenite. All the results show that a great amount of magnesium in Panxi ilmenite uniformly substitutes for iron in the structure of ilmenite, while a minority magnesium exists in gangue minerals, and calcium more likely exists in gangue minerals. The sites of magnesium, calcium and iron in ilmenite would not be redistributed during the treatment of mechanical activation. [Copyright &y& Elsevier]

Abstract: Plagioclase (NaAlSi3O8–CaAlSi2O8) is one of the dominant impurity minerals in the ilmenite concentrate from the Panxi area of China. The effects of mechanical activation on the structural changes of plagioclase and ilmenite single minerals from Panxi were investigated using X-ray diffraction (XRD), particle size analysis, and scanning electron microscope (SEM). Hydrochloric acid leaching behaviors of mechanically activated plagioclase and ilmenite single minerals and their mixtures were also studied. The results show that with increasing milling time, the crystallite size, lattice strain and the particle size changed continuously but differed between plagioclase and ilmenite. Mechanical activation enhanced the leaching reactivity of plagioclase and ilmenite with 20% HCl at 105°C, consistent with the lattice disorder and decreased particle size. The leaching of plagioclase was hardly affected by the existence of ilmenite, but the leaching of ilmenite was inhibited when plagioclase co-existed in the sample which is attributed to silica gel produced from leached plagioclase blocking the surface of unleached ilmenite. [Copyright &y& Elsevier]

Under the condition of paucity of mantle-derived ferromagnesian components, peritectic assemblage entrainment (PAE) model can properly explain a large variation of Fe, Mg, Ti, and Ca contents as well as positive linear trends for Ti and Ca plotted against maficity (molar Fe + Mg) exhibited by more mafic I-type granitic melts. Herein we present a comprehensive study of zircon U–Pb–Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotopes for newly identified Neoproterozoic high-maficity I-type granitoids collected from the Yonglang area in the western Yangtze Block, South China, in order to evaluate PAE process acting on the petrogenesis of these more mafic granitoids. Zircon U-Pb geochronological results show that the Yonglang granitoids, including the granodiorites, monzogranites, and biotite granites, yield the weighted mean 206Pb/238U ages of ca. 850–825 Ma. They are geochemically characterized by high SiO 2 (64.63–72.62 wt.%) and K 2 O (3.49–6.59 wt.%) contents as well as variable A/CNK (0.94–1.09) and molar Fe + Mg values (0.0452–0.1210), and display a negative correlation of A/CNK and Fe + Mg, indicating an I-type affinity. Isotopically, they display negative whole-rock εNd(t) (−4.06 to−6.38) and highly evolved zircon εHf(t) values (−9.36 to +1.92) as well as old two-stage Nd model ages (1.69–1.85 Ga) and crustal Hf model ages (1608–2139 Ma), implying a crustal source. In comparison with the geochemical composition of fluid-absent experimental melts, the Yonglang I-type granitoids have Fe, Mg, Ti, and Ca contents that are too high to equilibrium with those of pure crustal melts, indicating the additional incorporation of a ferromagnesian, Ti-, and Ca-rich component into primary melts. Like the Cotoncello–Monte Capanne granitic complex in Elba Island and Verdenburg I-type granite in South Africa, the Yonglang I-type granitoids exhibit highly positive linear correlations for Ti vs. maficity and Ca vs. maficity as well as negative correlation for A/CNK vs. maficity, suggesting that these high-maficity I-type granitoids predominantly underwent the peritectic assemblage entrainment of Ca-Fe-Mg-Ti bearing minerals (e.g., clinopyroxene, plagioclase, ilmenite, etc.) during coupled melting of biotite and hornblende phases in crustal source. The process of peritectic assemblage entrainment thus play a vital role in moulding geochemical compositions of more mafic I-type granites. [Display omitted] • Newly identified Neoproterozoic high-maficity I-type granitoids were formed at ca. 850-835 Ma. • They originated from coupled melting of biotite and hornblende phases in ancient crustal source. • They predominantly underwent the peritectic assemblage entrainment (PAE) process. [ABSTRACT FROM AUTHOR]

SLon vertical ring pulsating high gradient magnetic separators possess the advantages of a large beneficial ratio, high processing efficiency, strong adaptability, high resistance of the magnetic matrix to clogging, and high equipment availability. In recent years, these separators have been successfully applied to the beneficiation of ilmenite ores at the Panzhihua Ilmenite concentrator, and several other ilmenite processing plants, promoting the rapid development of the ilmenite industry in China. [ABSTRACT FROM AUTHOR]

Focuses on Fe-Ti oxide and Fe-Cu sulfide exsolution phases found in the amphibole cumulate xenoliths from Mesozoic granodioritic plutons at Jiguanshi and Jinkouling in Tongling, Anhui Province. Identification of most of the amphiboles in the xenoliths as pargasite; Mention of the crystallization phase in the lower crust; Distribution of the oxide exsolutions, commonly acicular and with a typical Schiller texture; How they correspond to magnetic, titaniferous magnetic, titanomagnetite or ilmenite; Finding that exsolved sulfide grains are arranged in sub-paralleled or closely beaded groups, with the exception of a few grains being scattered or isolated; Composition of the exsolved sulfide phases with pyrrhotite, cubanite and chalcopyrite, and rarely pyrite; Finding that a few grains of magnetic can coexist with pyrrhotite; The amounts of nickel in the sulfide phases and copper in the pyrrhotite; Assertion that both oxides and sulfides can be exsolved in the same amphibole area; Inference that ore-forming materials were dissolved in magma within the lower crust of the Tongling area.

• Inclusion-type staurolite further defines the prograde metamorphic stage and P-T conditions. • U–Pb age data reveal that timing of peak metamorphism is approximately 1839–1831 Ma. • A clockwise P–T–t path has been reconstructed, indicating a continuous continental collision and tectonic uplift process. The Zanhuang Complex, situated on the eastern margin of the central section of the Trans-North China Orogen (TNCO), North China Craton, mainly comprises Archean-Palaeoproterozoic tonalite-trondhjemite-granodiorite (TTG) gneisses, migmatites, granites, metavolcanic rocks, and metasedimentary rocks. Petrographic observations of garnet-bearing pelitic gneisses from the south-eastern Zanhuang Complex show three distinct mineral assemblages (M 1 -M 3) that correspond to three different metamorphic stages. The interpreted prograde metamorphic stage (M 1) is mainly represented by the cores of garnet porphyroblasts with fine-grained inclusions of biotite + plagioclase + staurolite + kyanite + quartz + ilmenite. The peak metamorphic stage (M 2) is mainly represented by garnet mantles and a matrix-type mineral assemblage of kyanite + biotite + plagioclase + quartz + ilmenite + melt. The retrograde metamorphic stage (M 3) is represented by the presence of sillimanite with garnet rims + biotite + plagioclase + quartz + ilmenite + magnetite. Quantitative phase equilibria modelling constrains the pressure–temperature (P–T) conditions of the M 1 and M 2 stages to 640–670 °C/7.3–7.5 kbar and 705–760 °C/7.9–9.1 kbar, respectively. The zircons and monazites in the Zanhuang pelitic gneisses all record consistent ages of 1839–1831 Ma, which most likely represent the near-peak metamorphic age. Thus, a clockwise P-T- time (P-T-t) path is determined for the garnet-bearing pelitic gneisses from the Zanhuang Complex. The petrological and geochronological evidence from the pelitic gneisses in the Zanhuang Complex in this paper suggests that the TNCO might have experienced continuous continental collision and rapid tectonic uplift at ca. 1839–1831 Ma, thereby providing a metamorphic constraint on the Palaeoproterozoic tectonic evolution of the TNCO. [ABSTRACT FROM AUTHOR]

• The future utilization trend of titanium resource will be largely relied on ilmenite. • Combined processing technologies will be more effective in ilmenite dressing. • Flotation proves to be an indispensable step for ilmenite upgrading in future. • Future research needs on ilmenite beneficiation are discussed. Ilmenite, as the main titanium source in practice, is of critical importance in meeting the pressing needs of various titanium associated fields. Herein, a review of ilmenite mineral processing by flotation is conducted to systemise the development of technologies in ilmenite upgrading. It proves that Australia and China are the top two countries with higher titanium reserves than other countries but with different metallogenic mechanisms. The basic properties of ilmenite and its metallogenic mechanism codetermine the final choice for ilmenite-containing ores beneficiation. Flotation has been an indispensable step for ilmenite upgrading as time goes and many collector types that can float ilmenite in different pH ranges have been developed. To date, various surface modification methods have proven to be a research hotspot. How to improve the flotability of fine ilmenite and comprehensive recycling of those historic ilmenite-containing tailings are much deserved in future. [ABSTRACT FROM AUTHOR]

• High-Al and High-Cr chromitites are distinguished in the Sartohay ophiolitic mélange. • High-Al chromitites formed by the interaction between MORB-like melts and harzburgites in a back-arc spreading ridge. • High-Cr chromitite fragments initially formed by boninitic melts in an arc-related setting. Primary high-Al [Cr# = 100 × Cr/(Cr + Al) of 48.2–54.7] chromitites coupled with high-Cr (Cr# = 70.9–80.7) chromitite fragments are identified in the podiform chromitites hosted by the Sartohay ophiolitic mélange in west Junggar, northwest China. New petrographic and mineralogical data for chrome-spinels in both types of chromitites and their host harzburgites, as well as inclusions within chrome-spinels, are reported here to reveal the genesis of the Sartohay chromitites. Abundant primary monomineralic and polymineralic mineral inclusions including Na-phlogopite, enstatite, diopside, pargasite, olivine, rutile, ilmenite, sulphide, and occasionally zircon are found in the high-Al chromitites. Chemical compositions of these mineral inclusions indicate that the trapped melts are rich in H 2 O, Na 2 O, and TiO 2. Temperatures and pressures estimated based on the equilibrium of mineral phases within inclusions are 812–992 ℃ and ~10.6 kbar, respectively. The calculated parental melt compositions (Al 2 O 3 = 15.0–16.1 wt%; TiO 2 = 0.30–0.96 wt%; Co = 37.0–48.2 ppm; Ga = 11.2–13.3 ppm) in equilibrium with high-Al chromitites suggest that these chromitites probably formed by the interaction between MORB-like melts and intermediate depleted harzburgites. In contrast, the high-Cr chromitite fragments with needle-shaped clinopyroxene lamellaes are entirely free of globular hydrous silicate inclusions. The parental melt compositions (Al 2 O 3 = 10.3–12.2 wt%; TiO 2 = 0.11–0.26 wt%; Co = 55.8–60.4 ppm; Ga = 13.4–17.2 ppm) in equilibrium with high-Cr chromitites show boninitic affinity. We propose that the high-Cr chromitites initially formed at an arc-related environment, then the deep recycling and uplift events occurred and resulted in high-Cr chromitites occurring as residual fragments in a back-arc basin spreading ridge. Subsequently, high-Al chromitites were formed and mechanically juxtaposed with the pre-existing high-Cr ones in the Sartohay ophiolitic mélange. [ABSTRACT FROM AUTHOR]

The article discusses the research study conducted that examines the genetic types of mineral deposits of Xiongcun District in Gangdese porphyry copper belt in Tibet, People's Republic of China (PRC). It mentions the genesis of the Gangdese deposit as epithermal, porphyry, and porphyry-epithermal deposit. It further mentions that the deposit is characterized by developed pyrrhotite and ilmenite, that have similar mineral assemblages to the reduced porphyry copper-gold deposit (RPCDs).