Search

The Xiaoqinling gold province, located in the southern margin of the North China Craton (NCC), is the second largest gold-enriched region in China. In this region, the Mesozoic Huashan (HS) and Wenyu (WY) plutons are the major magmatic intrusions coeval with gold mineralization, although they show contrasting characteristics in the distribution of gold. In this study, we use geochemical features of titanite determined by LA-ICP-MS and EPMA analyses and elemental mapping to decipher the mechanisms that led to the difference in gold enrichment related to the two plutons. Titanite from the Wenyu granitic pluton exhibits significantly higher (La/Sm)N, (La/Yb)N, ΣLREE/ΣHREE ratios, and ΣREE concentration and slightly higher (Gd/Yb)N values than those of the Huashan Pluton, suggesting that the Wenyu pluton might have experienced more complex magmatic evolution, widespread hydrothermal alteration, and higher silica activity in the melt than the Huashan pluton. The titanite grains from the Huashan pluton show higher (Nb/Ta)N and (Lu/Hf)N values and significantly lower Zr concentration than those of the Wenyu pluton. The titanite grains from the Wenyu pluton show higher vanadium and gallium concentrations and Fe/Al ratio than those of the Huashan pluton, indicating comparatively higher f o 2 . Furthermore, the titanite grains from Wenyu pluton indicate higher water content in the magma. In addition, magma mingling and magmatic hydrothermal fluids derived from the crust/mantle are critical sources for ore-forming materials. These results suggest that the Wenyu pluton is more conducive to gold migration and enrichment than the Huashan pluton. [ABSTRACT FROM AUTHOR]

The giant Changba-Lijiagou (Ch-L) Pb-Zn deposit is in the northeast part of the Xicheng ore cluster, Western Qinling Orogen. The ore genesis remains controversial; it could be either a sedimentary exhalative genetic type or an epigenetic hydrothermal genetic type. Here, in situ titanite U-Pb dating for the two kinds of titanite is presented, yielding ages of 212.8 ± 3.0 Ma in the mineralized skarn ore and 214.6 ± 5.1 Ma in the host rock. These ages conform to the previously reported magmatic zircon age (229–211 Ma) based on the in situ zircon U-Pb dating of plutons in this district and the time of large-scale magmatic–hydrothermal activities in Western Qinling Orogen (229–209 Ma). Titanites occurring in mineralized skarn and those that are calcite-hosted are similar to hydrothermal-origin titanites in major element characteristics. The Eu anomalies in the two types of titanite record oxidizing conditions during the mineralization process. A mineral assemblage of garnet, pyroxene, riebeckite, biotite, and potash feldspar, replacing the albite, is well-developed in the deposit. The mineralogical and geochronological characteristics indicate that the Ch-L Pb-Zn deposit is a distal skarn deposit and the result of intensive tectonomagmatic processes in the Xicheng ore cluster during the process of the Late Triassic orogeny. [ABSTRACT FROM AUTHOR]

The Taimyr Peninsula in the Russian High Arctic comprises a late Paleozoic-early Mesozoic collisional belt where several porphyry-type mineralization occurrences were identified during the last decade, making this area a potential exploration target for Cu-Mo deposits. In order to further evaluate the metallogenic potential of the poorly outcropped northeastern part of Taimyr, samples from seven granitoid intrusions were investigated in this study aimed to evaluate the granite fertility based on petrography, geochemistry, and composition of porphyry indicator minerals (zircon, apatite, and titanite). The studied intrusions represent small to moderate-sized bodies (40–800 km2) composed of biotite (±amphibole) quartz monzonites, granodiorites, granites, and biotite leucogranites that formed in the course of late Paleozoic-early Mesozoic tectono-magmatic events at the Siberian margins. The late Carboniferous Tessemsky massif represents suprasubduction granitoid series, while the Pekinskiy, Shirokinskiy, Dorozhinskiy, Kristifensenskiy, and Yuzhno-Lodochnikovskiy massifs are correlated with the early Triassic Siberian Traps LIP. The rocks of intrusions comprise a relatively uniform geochemically, predominantly magnesian, slightly peraluminous, calc-alkaline high-K amphibole-bearing I-type granitoid series with adakitic affinity, where Triassic plume-related granitoids inherit geochemical signatures of Carboniferous supra-subduction granitoids, and all rock types are marked by enrichment in LILE and negative Ta, Nb, and Ti anomalies. It is suggested that the adakitic geochemical characteristics of the Taimyr granites are a result of derivation from a relatively homogeneous mafic lower crustal source that formed at the stage of Carboniferous continental subduction and continued to produce granitic melts in the course of the early Mesozoic magmatic evolution. Whole rock geochemistry and composition of porphyry mineral indicators (zircon, apatite, and titanite) indicate that the Taimyr granites crystallized from oxidized water-saturated magmas at moderate temperatures, with the majority of samples showing characteristics typical for porphyry-fertile granites worldwide (fO2 = ΔFMQ +1 to +3 with zircon Eu/Eu* > 0.4 and apatite SO3 > 0.2 wt.%). Data from Dorozhinskiy, Kristifensenskiy, Pekinskiy, and Tessemskiy intrusions fully match geochemical criteria for porphyry-fertile granitoids, and these massifs are considered the most prospective for Cu-Mo mineralization. Granites from Shirokinskiy and Yuzhno-Lodochnikovskiy intrusions only partially match compositional constraints for fertile melts and can be considered as second-tier exploration targets. Finally, available data for the Simsovsky massif preclude its classification as a porphyry-fertile body. These conclusions are in line with previously developed exploration criteria for the northeastern Taimyr, showing that geochemical indicators of granite-fertility can be used on a regional scale in parallel with other exploration methods. [ABSTRACT FROM AUTHOR]

Blast furnace slag glass–ceramics were prepared by melting using rare-earth-containing blast furnace slag (REBFS) as the main raw material and Fe 2 O 3 and Cr 2 O 3 as composite nucleating agents. By adding different TiO 2 contents, the study comprehensively revealed the effects of high field strength ions on the glass network structure, crystalline properties, elemental distribution and physicochemical properties. Raman spectroscopy and differential scanning calorimetry revealed that TiO 2 acted primarily as a network modifier in the glass network. The appropriate TiO 2 content disrupted the glass network, decreasing the crystallization activation energy (E C) of the glass–ceramic. However, excess TiO 2 repaired the network structure, thereby increasing the E C. The combined effect of the Cr and Ti substantially improved the crystallization characteristics of the glass-ceramics. Cr 2 O 3 induced the formation of spinel, which promoted the crystallization of the main crystalline augite phase. The self-aggregation of the high field strength Ti4+ ion induced the formation of a titanium- and cerium-containing titanite phase, which also contributed to grain refinement. This titanite phase effectively increased the Vickers hardness and acid and alkali resistances of the glass-ceramics to 9.16 GPa and over 98.5 %, respectively. The excellent physicochemical properties render REBFS glass–ceramics as being promising materials for various construction applications. This research provides theoretical support for comprehensively utilizing blast furnace slag and provides theoretical guidance for preparing slag glass–ceramics possessing desirable physicochemical properties. [ABSTRACT FROM AUTHOR]

Seven experiments exploring the reaction of titanite with various hydrothermal solutions have been carried out at 700 °C and 200 MPa for a run duration of 16 days. In experiments involving fluids consisting of NaCl+H2O, KCl+H2O, CaCl2+H2O, 2M NaOH, or 2M KOH, no reaction of the titanite with the fluid was observed other than a slight dissolution of the titanite. Experiments involving NaF+H2O and Ca(OH)2+H2O resulted in visible alteration of the titanite in texture and composition, coupled with the formation of perovskite. In the NaF+H2O experiment, perovskite, enriched with rare earth elements (REE), formed as euhedral to subhedral crystals on the surface of the recrystallized titanite. In the Ca(OH)2+H2O experiment perovskite took in minor amounts of REE, and formed as a reaction rim partially replacing the titanite via a coupled dissolution-reprecipitation reaction. Wollastonite, along with minor calcite, and grossular garnet, formed as an outer rim on the perovskite. In the NaF+H2O experiment major and trace elements were leached from the titanite, whereas in the Ca(OH)2+H2O experiment no leaching of major or trace elements was observed. Nb/Ta, Th/U, and Y/Ho were investigated as potential indicators of hydrothermal processes. While the Nb/Ta ratio was altered in the experimentally metasomatised titanite, the degree of alteration was the same for both fluids. In contrast, only small changes in the Th/U and Y/Ho ratios between the altered and original titanite were seen for either experiment. The formation of perovskite at the expense of titanite in NaF+H2O or Ca(OH)2+H2O fluids demonstrates how titanite reacts with these fluids in simple, low silica activity systems under mid to upper crustal P-T conditions. [ABSTRACT FROM AUTHOR]

To address the limitations of current dating methods, it is crucial to not only enhance existing techniques like U–Pb zircon dating but also explore alternative tools. This study focuses on three common mineral phases—zircon, apatite, and titanite—in an I-type granite. The goal is to assess their reliability as dating tools and propose improved methods for dating granitic rocks. In the case study of the Mt Stirling pluton within the Mt Buller igneous suite in Southeastern Australia, significant variability in laser ablation U–Pb zircon ages (around 100 million years) was observed. To improve the reliability of zircon age data and reduce non-magmatic-related variabilities, a data filtering protocol is applied. This protocol involves several steps such as trimming zircons with excessive K and Ca, excluding zircons with unusual core–rim age relationships, removing zircons with excessive non-formula elements (Al, Fe, and Mn), identifying hydrothermally altered zircons, and applying a 10% discordance threshold. The filtered Concordia Age (406 ± 1 Ma; mean square weighted deviation (MSWD) = 0.7, n = 80) of the host rock exhibits improved precision and reduced error compared to the unfiltered data (399 ± 2 Ma; MSWD = 9.3, n = 240). The filtered individual dates show less scatter and a mean that is different (i.e. outside statistical uncertainty), noting that their total still spans a considerable time range of ~50 million years, exceeding the individual zircon analytical reproducibility of 2 standard errors (~15 million years of 2 SE). Caution is advised when using the proposed error for the pooled analyses as a definitive precision. Similarly, trace element filtering approaches were applied to apatite and titanite samples from Mt Stirling, two phases that arguably cannot be inherited. For apatite, monitoring Ca and P as well as Zr/Y and Th/U ratios, along with identifying age groupings based on Sr concentrations, was effective in eliminating outliers and enhancing dating precision. In the case of titanite, monitoring Ca and Ti, Sr/Zr and Sr/Th ratios, and Sr/Ca and Zr/Ti ratios successfully enhanced dating precision. Notably, apatite and titanite grains were grouped in distinct Sr concentrations (high-, mid-, and low-Sr), with these groups corresponding to different date groups: high-Sr apatite and high- and low-Sr titanite returned c. 403 Ma, while low-Sr apatite and mid-Sr titanite returned c. 420 and 393 Ma, respectively. The spuriously younger or older dates may indicate an open system and influences from various common-Pb sources. The 403 Ma date coincides with the filtered zircon data, placing further confidence in the coupled approach, and is interpreted here as the igneous intrusion age. Notable is that this age is 25 Myr older than previously reported K–Ar age data, thus far considered to be the age of the intrusion. This study underscores the potential for erroneous zircon dates due to cryptic chemical influences. To enhance the reliability of age interpretation using laser ablation analyses, employing a petrochronological approach using split-stream combined age and trace element data is recommended in addition to the combination of multiple geochronometers. In the case of Mt Buller, it has proven crucial to carefully verify chemical closure of all applied geochronometers by monitoring concomitant trace element concentrations. Applied to other intrusions, petrochronology can play a critical role in obtaining reliable age information, even for igneous rocks that appear pristine. With this, we emphasise the importance of a careful approach towards individual age data interpretation, which can be produced fast and in abundance with modern analytical approaches. [ABSTRACT FROM AUTHOR]

Garnet granulite xenoliths from the Nurbinskaya diatreme in the central part of the Archean Anabar province in Siberia are fragments of the local lower crust that experienced multiple metamorphic events in the Paleoproterozoic and reheating events in the Mesoproterozoic and later. This study addresses the timing of metamorphic transformations, and constrains the cooling rate and the time of stabilization of the lower crust. The observed metamorphic mineral assemblage of garnet, clinopyroxene, plagioclase, amphibole, rutile and ilmenite was formed at ~ 800 °C, 1.1–1.2 GPa under water-undersaturated conditions at ~ 1.88 Ga. However, the mineral assemblage is not well equilibrated and retains evidence of earlier and subsequent metamorphic stages. Late titanite formed in response to hydrous fluid influx according to phase equilibria modeling. U-Pb dating shows two events of titanite formation at 1850 ± 5 Ma and at 1788 ± 2 Ma. After deformation, which led to the porphyroclastic rock textures, the granulites underwent near-isobaric cooling. The cooling rate was higher than ~ 6 °C/Myr, to retain the garnet compositional zoning. Rutile ages are discordant, with 207Pb/206Pb dates ranging from 1.43 to 1.53 Ga. However, rutile may have responded to earlier thermal pulses, and was also reset later, so it does not record the stabilization of the crust. Crustal stabilization after Paleoproterozoic orogenic events may have occurred shortly after titanite formation. [ABSTRACT FROM AUTHOR]

The Xiaoqinling gold province, located in the southern margin of the North China Craton (NCC), is the second largest gold-enriched region in China. In this region, the Mesozoic Huashan (HS) and Wenyu (WY) plutons are the major magmatic intrusions coeval with gold mineralization, although they show contrasting characteristics in the distribution of gold. In this study, we use geochemical features of titanite determined by LA-ICP-MS and EPMA analyses and elemental mapping to decipher the mechanisms that led to the difference in gold enrichment related to the two plutons. Titanite from the Wenyu granitic pluton exhibits significantly higher (La/Sm)N, (La/Yb)N, ΣLREE/ΣHREE ratios, and ΣREE concentration and slightly higher (Gd/Yb)N values than those of the Huashan Pluton, suggesting that the Wenyu pluton might have experienced more complex magmatic evolution, widespread hydrothermal alteration, and higher silica activity in the melt than the Huashan pluton. The titanite grains from the Huashan pluton show higher (Nb/Ta)N and (Lu/Hf)N values and significantly lower Zr concentration than those of the Wenyu pluton. The titanite grains from the Wenyu pluton show higher vanadium and gallium concentrations and Fe/Al ratio than those of the Huashan pluton, indicating comparatively higher fo2. Furthermore, the titanite grains from Wenyu pluton indicate higher water content in the magma. In addition, magma mingling and magmatic hydrothermal fluids derived from the crust/mantle are critical sources for ore-forming materials. These results suggest that the Wenyu pluton is more conducive to gold migration and enrichment than the Huashan pluton.

Giant Nb deposits hosted by alkaline igneous rocks worldwide are characterized by hydrothermal and/or metamorphic modifications after magmatic crystallization. However, the impact of secondary processes on Nb mineralization in alkaline igneous rocks remains controversial. In this study, U–Pb ages, elemental, and Nd isotope compositions of titanite from a series of Nb-rich dyke swarms in the Ziyang region of South Qinling (China) have been investigated to unveil Nb remobilization and enrichment histories during magmatic and hydrothermal processes. Three types of titanite are documented: magmatic, deuteric, and hydrothermal. The magmatic titanite (Ttn I) grains are euhedral wedge-shaped, while the deuteric type (Ttn II) occurs as coronas on magmatic ilmenite. The hydrothermal titanite (Ttn III) occurs as either bead-like clusters within the cleavage planes of chloritized biotite or as anhedral grains (lesser than 200 μm in diameter) coexisting with hydrothermal actinolite, chlorite, fluorite, and/or REE-rich oxides. The magmatic titanite grains from the most primitive igneous rocks have U–Pb ages of 455 ± 25 Ma and are characterized by high levels of Nb2O5 (up to 1.4 wt%) and other high field strength elements (HFSE, up to 1.3 wt% ZrO2), rare earth elements (REE), and V, and high mean crystallization temperatures (880 ± 40 °C), suggesting that they nucleated and crystallized in a high-T and Nb-rich alkaline magma during the Early Paleozoic. The gradual decrease in V, Sr, and Ba in Ttn I from mafic to intermediate dykes exemplifies the role of fractionation on magmatic enrichment of Nb (mean of 170 ppm and 7300 ppm for Ttn I in mafic and intermediate dykes, respectively) and other incompatible elements (e.g., Ta, Zr, Hf, Sn, Y, and REE) in the residual melt. The deuteric and hydrothermal types of titanites in each lithology have lower concentrations of HFSE (e.g., Nb mean of 140 ppm and 860 ppm for Ttn II in mafic and intermediate dykes, respectively), Sn, LREE, and Y but higher Al, F, V, Sr, and HREE contents than their magmatic counterpart. The deuteric and hydrothermal types of titanite have U–Pb ages of 420 ± 25 Ma and 232 ± 49 Ma, respectively, supporting two distinct hydrothermal events at Ziyang. The magmatic and deuteric types of titanite have similar ranges of εNd(t) values (+ 1.4 to + 3.5 and + 2 to + 4.2, respectively), indicative of a common source for these two generations. The hydrothermal titanite also has comparable εNd(t) values (+ 0.8 to + 2.7) to the magmatic and deuteric types, indicating a minimal external contribution to Nd (and by analogy Nb as well) from the late hydrothermal fluids. The deuteric and late hydrothermal F-rich fluids in Ziyang dyke swarms both remobilized the dispersed Nb in magmatic ilmenite, amphibole, and biotite to form secondary titanite (Ttn II, III), which is beneficial to the metallurgical extraction of this critical metal. Therefore, both magmatic fractional crystallization and hydrothermal remobilization contributed to Nb mineralization. [ABSTRACT FROM AUTHOR]

Titanites can be excellent markers of element transfer in medium-temperature retrograde metamorphism. Euhedral titanites from several alpine fissures from Mont Blanc, particularly those of Périades and Courtes, crystallised at the end of the main quartz stage and are synchronous with the formation of green biotites and albite before chlorite formation. Micro-XRF, SEM, electron probe, and LA-ICP-MS analyses show that these titanites have a wide range of Al2O3 content from 1 to 8%, are dominated by -OH versus F, and have a wide range of Nb (up to 4500 ppm), Y (up to 3000 ppm), Zr (up to 1800 ppm), and Sn (up to 1400 ppm) concentrations. The allanite from the granite, partly destabilised into epidote, is the most likely source of Nb, Y, Zr, Sn, and REE. Titanites are enriched in HREE and show variations in LREE depending on the studied sites. Like quartz, they formed at around 400 ± 20 °C, which is compatible with the formation of green biotites after the destabilisation of granite Fe-Mg silicates. This early stage of fluid circulation, synchronous with the Mont Blanc massif uplift, is therefore marked by the titanite formation at the transition between the biotite and chlorite stability fields. [ABSTRACT FROM AUTHOR]

In-situ dating of the zircons, titanites, and apatites in the rock fragments of approximately 1 cm2 in size from the Acasta Gneiss Complex was performed using secondary ion mass spectrometry or laser ablation inductively coupled plasma mass spectrometry to provide constraints on the thermal history of the Acasta Gneiss Complex. The zircons in these rock fragments typically exhibit multiple age populations, reflecting the presence of inherited zircons or the post-crystallization process of zircon overgrowth. Combined with previous studies, our zircon dating results reveal multiple magmatic events that occurred in the Acasta Gneiss Complex, specifically at >3.96, ∼3.72, and ∼3.57 Ga, respectively. A titanite Pb-Pb isochron age of 2911±22 Ma (95% confidence level, MSWD=1.5) for sample AY199 is identified, consistent with the timing of the latest Archean magmatism in the Acasta Gneiss Complex. The titanite U-Pb ages for samples AC478 and AY066 are 1932±270 Ma (95% confidence level, MSWD=2.3) and 1813±45 Ma (95% confidence level, MSWD=2.3), respectively. The apatites in sample P090803-C exhibit a Pb-Pb isochron age of 1833±26 Ma (95% confidence level, MSWD=1.4). The apatite U-Pb ages for samples AC478, AY199, and AY066 are 1850±20 Ma (95% confidence level, MSWD=1.3), 1827±100 Ma (95% confidence level, MSWD=6.3), and 1807±58 Ma (95% confidence level, MSWD=3.9), respectively. Titanites in samples AC478 and AY066, as well as the apatites in all four investigated samples, show a uniform age (Pb-Pb or U-Pb age) of ∼1.9–1.8 Ga, indicating U-Pb system reset in these minerals due to the Wopmay orogeny and documenting that the peak temperature condition associated with the Wopmay orogeny exceeded the apatite U-Pb closure temperature and approached or exceeded that of titanite. [ABSTRACT FROM AUTHOR]

Iron‐titanium oxides such as ilmenite (FeTiO3), titanite (CaTiSiO5) and perovskite (CaTiO3) are the common Ti‐rich mineral phases crystallised during magmatic and metamorphic processes on Earth. Depending on magma types or conditions of phase equilibria, formation of these Ti‐rich minerals can result in Ti isotopic fractionation in the range of ‐1.52‰ to +2.90‰ on δ49TiOL‐Ti (i.e., the per mil difference of 49Ti/47Ti ratio relative to the OL‐Ti reference material), making the Ti isotope ratios of these minerals potential tracers for conditions of magmatism and metamorphism. Due to their resistance to aqueous alteration, these Ti‐rich accessory minerals are also commonly present as pristine, detrital phases in sedimentary rocks, which offer an opportunity to study the evolution of magmatism and metamorphism throughout the Earth's geological history. Here we have developed a novel technique for in situ Ti isotopic measurement in ilmenite, titanite and perovskite using femtosecond laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (fs‐LA‐MC‐ICP‐MS) under wet plasma conditions. Samples were ablated with different laser spot sizes (15–50 μm) and different laser energy densities (0.6–4.2 J cm‐2) to obtain adequate Ti signal intensity at a fixed laser repetition rate of 2 Hz. When 49Ti signal intensity of samples ranged from 0.3 to 3.7 V, no significant signal‐dependent Ti isotopic fractionation was observed under wet plasma conditions. Repeated measurements on twelve Ti‐rich minerals using different analytical protocols provided comparable δ49TiOL‐Ti values within uncertainties, confirming the accuracy of the proposed fs‐LA‐MC‐ICP‐MS method. With one exception (i.e., RUS1), all analysed minerals are homogeneous in their Ti isotopic compositions between individual chips with an intermediate precision of ±0.13‰ to ±0.17‰ (2s) on δ49TiOL‐Ti. Collectively, these minerals record a significant δ49TiOL‐Ti variation ranging from ‐0.46‰ to +2.12‰. These warrant the suitability of these materials as Ti isotopic reference materials for in situ Ti isotopic measurement. [ABSTRACT FROM AUTHOR]

Ultrahigh‐pressure (UHP) rocks in North‐East Greenland lie within a larger region of high‐pressure Laurentian crust formed in the overthickened upper plate of the collision with Baltica. Coesite‐bearing zircon dates UHP metamorphism to 365–350 Ma, which formed at the end of the Caledonian collision as a result of intracontinental subduction facilitated by strike‐slip faults that broke the lithosphere. Rutile is the stable Ti‐bearing phase at UHP, while titanite forms on the retrograde path. Trace elements and U‐Pb in titanite were analyzed for six UHP gneisses. Zr‐in‐titanite temperatures range from 764 to 803°C and lie on the isobaric part of the pressure‐temperature path at 1.2 GPa, which fits Ti‐phase stability determined by thermodynamic modeling. Large (>600 μm), zoned titanite preserves three distinct trace element patterns that are due to metamorphism, melting and garnet breakdown. Weighted mean 206Pb/238U ages range from 347 ± 5 Ma to 320 ± 11 Ma, but age variation as a function of trace element domain for individual samples is not resolvable within uncertainty. Titanite records a prolonged period of exhumation that is also seen in the zircon record, where phengite decompression melting started at ca. 347 Ma, leucosome emplacement accompanied retrograde metamorphism from 350 to 330 Ma; and titanite grew during isobaric cooling from 345 to 320 Ma when the UHP rocks stalled at lower crustal levels. The same transforms that originally break the lithosphere play a significant role in channeling the UHP rocks back to the lower crust via buoyancy driven exhumation, after which time titanite formed. Key Points: A slice of Laurentian crust was subducted to ultrahigh‐pressure (UHP) conditions in a strike‐slip regime after Caledonian crustal thickeningTitanite grows on an isobaric cooling path from 345 to 320 Ma, after exhumation to the lower crust, consistent with previous zircon datingExhumation of an UHP slice to the lower crust was driven by buoyancy forces also in a translational setting [ABSTRACT FROM AUTHOR]

Titanite is a widespread accessory mineral in igneous, metamorphic, and hydrothermal rocks, but few comply with gem-grade requirements. Previous studies on Moroccan titanite focused on elementary composition and U-Pb dating. In this study, two gem-grade titanites (MA-1 and MA-2) from the Moroccan Central High Atlas were investigated through gemological and chemical studies, including infrared spectrum, Raman spectrum, SEM-EDS, and LA-ICP-MS. Two titanite samples are yellow, transparent–translucent with a greasy luster, 3.5 and 2.5 mm long. MA-1 and MA-2 have similar gemological properties, the refractive index (RI) is beyond the range of the refractometer (>1.78), the specific gravity (SG) values fall in the range of 3.52~3.54 and both are inert to short-wave and long-wave UV radiation. The spectral characteristics have high consistency with the RRUFF database. The major elements' composition shows a negative correlation between Al, Fe, V, and Ti, suggesting the titanites underwent substitutions such as (Al, Fe3+) + (F, OH) ↔ Ti + O. The titanite samples, characterized by a low abundance of REE (802~4088 ppm) and enriched in LREE, exhibit positive Eu (δEu: 1.53~7.79) and Ce (δCe: 1.08~1.33) anomalies, indicating their formation in a hydrothermal environment with low oxygen fugacity. The 238U/206Pb and 207Pb/206Pb ratios of the titanites yield lower intercept ages of 152.6 ± 2.2 and 151.4 ± 5.3 Ma (1s), consistent with their weighted average 206Pb/238U ages of 152.3 ± 2.0 and 150.7 ± 3.2 Ma (1s) respectively. The results of U-Pb dating are matched with the second main magmatic activities in the High Atlas intracontinental belt of Morocco during the Mesozoic to Cenozoic period. Moreover, the two titanite samples have almost no radiational damage. All the results show that the titanite from High Atlas, Morocco, has the potential to be a reference material for LA-ICP-MS U–Pb dating, but further experiments are needed to be sure. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of isotopic systems in minerals and rocks in southern margin of the epi-Archean Karelian craton in the zone of its junction with the Svecofennian mobile belt. U-Pb, Sm-Nd and Rb-Sr mineral ages of metamorphic rocks allowed reconstructing a T-t trend during ~1.88–1.61 Ga, which reflects a wide-ranging cooling history of metamorphic rocks from the peak values of about 650–700 °C at 1.88–1.79 Ga (U-Pb age of monazites and apparent oldest Sm-Nd age of amphiboles) to 300–400 °C at 1.61 Ga (model Rb-Sr age of biotites) in zones of low- and medium-temperature metamorphism. The specificity of removal of deep-seated rocks to the present-day erosion surface and the reconstructed T-t trend comply with the development of thrust-nappe structures during the exhumation of the Svecofennids. It is also assumed that differential vertical block movements played a significant role during the post-orogenic extensional collapse and neorifting.

Relevance. Development of new, highly effective reagents for treatment of wastewater of various origins is a complex and extremely important task. An equally pressing issue remains the development of technologies for processing large-scale mineral products, which currently have not found an economically feasible technology for their processing and have received the status of “waste”. The development of a technology for producing reagents using waste as a raw material will not only have an economic effect but will also significantly minimize the level of negative impact on the environment and take a step towards the implementation of the Zero Waste concept. Aim. Development of technology for processing large-scale titanium-containing raw materials to obtain complex titanium-containing reagents and study of their effectiveness in wastewater treatment from various industries. Methods. To study the phase composition of the samples, the X-ray diffraction method was used, and the determination of metal content in acidic solutions and wastewater was carried out by atomic emission spectroscopy. Results and conclusions. The authors have proposed the technology for production of complex titanium-containing coagulants, which includes hydrometallurgical technology for sulfuric acid processing of large-capacity mineral raw materials – titanite. Aluminum hydroxide was introduced into the resulting solutions to adjust the chemical composition and neutralize free sulfuric acid. The resulting aluminum sulfate transforms into the most stable form of 18-aqueous crystalline hydrate, absorbing moisture from the solution, realizing chemical dehydration. The study of the composition of solid samples of coagulants showed that the predominant phase in the composition of the complex coagulant is aluminum sulfate, and the content of titanium compounds ranges from 1 to 14 wt %. It was established that by varying the ratio of mineral raw materials:sulfuric acid it is possible to vary the amount of modifying additive titanium compounds in the complex reagent. It was proven that the use of complex titanium-containing coagulants in wastewater treatment allows reducing the consumption of coagulants by 25–35%, increasing the efficiency of water purification, minimizing residual concentrations of pollutants, and also significantly increasing the rate of sedimentation of coagulation sludge in comparison with traditional sulfate aluminum.

On the basis of the mineralogical-petrographic and geochemical study of igneous rocks of intermediate composition of the Pripyat complex of the Late Devonian Pripyat–Dnieper magmatism area, two subphases of the Pripyat magmatism phase have been distinguished: late Fransian (Chernin or Skolodino–Chernin) with potassium specification and early Famennian (Turov–Drozdov (Yelets)) with potassium-sodium specification. For the first time, the U–Pb age of titanite from trachyandesites of the parametric Pribor borehole was estimated for rocks of Pripyat–Dnieper magmatism area at 364 ± 1 Ma. These data confirm the Famennian age of the Yelets subphase of the Pripyat phase of magmatism and make it possible to estimate the duration of the magmatic activity of this structure at least 14 m.y. taking into account the isotope dating of the earliest phases of magmatism in the Pripyat–Dnieper–Donetsk Paleorift Structure as 388 ± 12, 383.3 ± 3.8, 384.7 ± 3.9, and 383.6 ± 4.4 Ma in the Azov Region and 381 ± 2 Ma in the Pripyat–Dnieper magmatism area. [ABSTRACT FROM AUTHOR]

Ion-adsorption rare earth element (REE) deposits in South China are currently the main source of heavy rare earth elements (HREE). The Gucheng deposit in western Guangdong Province is one example of HREE mineralization hosted in weathered coarse-grained biotite granites (CGBG). Titanite is a common accessory mineral in the CGBG and contains significant amounts of total REE (31 621 to 38 431 ppm), especially HREE (18 906 to 22 249 ppm). Titanite with a U-Pb age of 102.6 ± 1.9 Ma in the CGBG crystallized under relatively high temperatures (722–798 °C), high f H 2 O , and high f O 2 conditions in the late magmatic stage, and has similar Nd isotopic compositions similar to the host CGBG: 143Nd/144Nd = 0.512062 to 0.512125 and εNd(t) = –7.4 to –8.6. Backscattered electron (BSE) imaging and TESCAN integrated mineral analyzer (TIMA) measurements show that titanite in the CGBG has been altered partly to fergusonite-(Y), rutile, calcite, quartz, and fluorite. The hydrothermal fluid responsible for titanite alteration was enriched in C O 3 2 − and F, and was probably exsolved from the granitic magma. HREE released from the alteration of titanite were mostly scavenged by fergusonite-(Y) and rutile, which have been further replaced by gadolinite-(Y) and synchysite-(Ce). In addition, gadolinite-(Y) in the alteration assemblages exhibits further alteration and is characterized by elevated P O 4 3 − a n d S O 4 2 − contents in the altered parts. These results demonstrate that magmatic titanite in the CGBG underwent complex hydrothermal alteration, with a preferential accumulation of HREE in fergosnite-(Y) and gadolinite-(Y) in the alteration assemblages. Preferential HREE enrichments in magmatic titanite, and its alteration assemblages, are shown to play significant roles in the formation of the Gucheng HREE deposit. [ABSTRACT FROM AUTHOR]

The regolith-hosted rare earth element (REE) deposits in the Nanling Mountain Range, South China, are the most important source of heavy REE (HREE) in the world. A perplexing thing is that only a few of these deposits are relatively enriched in HREE and most of them are actually light REE (LREE)-enriched, although they are all originated from the granitic bedrocks with similar HREE concentrations. This is supposed to be related to the redistribution of REE in the weathered bedrocks due to groundwater-rock interaction, however, it remains enigmatic how REEs are mobilized and fractionated in the interaction. Titanite is an important REE contributor to the regolith-hosted REE deposit. Here, we investigate textural and compositional variations of the titanite from the granitic bedrocks to weathered profiles in the Zuokeng regolith-hosted REE deposit, the largest one that is newly discovered in this region. Together with thermodynamic modelling, we deduce the nature of the fluids, temperature range for titanite alteration, and the mechanism of REE fractionation. Primary titanite is of magmatic in origin and shows relatively high REE contents and negative Eu anomaly on the chondrite-normalized REE pattern. Secondary titanite is commonly associated with chloritized biotite and is characterized by extremely low REE, high Al2O3, F and significant positive Eu anomaly, typical of authigenic origin due to chloritization of biotite under oxidized conditions in supergene environment. From the bedrocks upward to the surface, primary titanite is gradually replaced by calcite, synchysite-(Ce) and TiO2 in the weathered bedrocks. This is interpreted as the result of infiltration of the F, carbonate-rich, alkaline fluids derived from local groundwater through the bedrocks. The irregular dark patches in primary titanite display typical alteration texture and may have formed through fluid leaching of primary titanite. The patches in primary titanite have lower REE concentrations and higher LREE/HREE ratios than magmatic domains, indicating that the groundwater preferentially scavenges HREE from primary titanite, leaving behind LREE in weatherable secondary minerals, such as synchysite-(Ce) and allanite. Mass balance calculation results also confirm that more HREE are lost from weathered bedrocks than LREE. Therefore, the interaction of groundwater and granitic bedrocks may be favorable to enrich LREE rather than HREE in the regolith. This may explain why most regolith-hosted REE deposits like Zuokeng in South China are of predominant in LREE. This study highlights the role of groundwater in mobilizing, fractionating and enriching REE from the granitic bedrocks to resultant regolith-hosted REE deposits. [ABSTRACT FROM AUTHOR]

The Osnytsky block is a constituent part of the Osnytsky-Mikashevytsky volcano-plutonic belt. The leading place in the geological structure of the Osnytsky block is occupied by the rock association, which includes a number of plutonic formations from gabbro to leucocratic granites (gabbro-diorite-granodiorite-granite association), formed in the Paleoproterozoic — 1,98—1,95 Ga. The results of lead-lead isotope dating of titanites from diorites, opened by the RPZ-5 quarry, located in the northwestern vicinity of the village Tomashhorod. Diorites were formed in the second phase, after gabroids, before the beginning of the formation of granitoids. The age of 1975 ± 9,1 Ma was obtained for them. The age calculated based on previously published data is 1973 ± 8,3 Ma, which is in good agreement with the U-Pb isotopic age of the zircons of these diorites 1974 ± 1,2 Ma. It was found that to determine the isotopic age of titanites with a high content of ordinary lead, it is enough to use only the isotopic composition of lead, calculating the age in the coordinates of the graph 207Pb/204Pb — 206Pb/204Pb, by the tangent of the angle of inclination of the regression line.

Titanites can be excellent markers of element transfer in medium-temperature retrograde metamorphism. Euhedral titanites from several alpine fissures from Mont Blanc, particularly those of Périades and Courtes, crystallised at the end of the main quartz stage and are synchronous with the formation of green biotites and albite before chlorite formation. Micro-XRF, SEM, electron probe, and LA-ICP-MS analyses show that these titanites have a wide range of Al2O3 content from 1 to 8%, are dominated by -OH versus F, and have a wide range of Nb (up to 4500 ppm), Y (up to 3000 ppm), Zr (up to 1800 ppm), and Sn (up to 1400 ppm) concentrations. The allanite from the granite, partly destabilised into epidote, is the most likely source of Nb, Y, Zr, Sn, and REE. Titanites are enriched in HREE and show variations in LREE depending on the studied sites. Like quartz, they formed at around 400 ± 20 °C, which is compatible with the formation of green biotites after the destabilisation of granite Fe-Mg silicates. This early stage of fluid circulation, synchronous with the Mont Blanc massif uplift, is therefore marked by the titanite formation at the transition between the biotite and chlorite stability fields.

Although the evolution of residual melts in magmatic systems controls their eruptability and ore-forming potential, their compositions are obscured in plutonic rocks by a protracted near-solidus evolution and the absence of interstitial glass. Here, we trace the evolution of residual melt compositions in rocks from the Strontian Intrusive Complex, Scotland, using the trace element chemistry of amphiboles, and titanites which are intergrown with amphibole rims. Laser ablation mapping reveals an abrupt change in certain trace elements in the amphibole rims, with sharp increases in Eu/Eu* and Sr/Y, and decreases in rare earth elements, Ta, Nb, and Ta/Nb ratios. Core-rim variations in these elements in titanite show the same variations as in amphibole, but are more gradual. By reconstructing the crystallisation sequence of the Strontian magmas using textural observations and thermobarometric estimates, we determine that amphibole cores crystallised prior to titanite saturation, but amphibole rims crystallised simultaneously with titanite. Using the trace element composition of the mineral phases and their modal abundance in the rock, with comparison to the whole-rock chemistry, we determine that titanite hosts the majority of the rare earth and high field strength element budget of the rocks. We therefore propose that the onset of titanite crystallisation had a profound effect on the trace element composition of late-stage residual melts at Strontian, which were inherited by the amphibole rims and subsequent titanites. This is supported by Rayleigh fractional crystallisation modelling, which demonstrates that the composition of amphibole rims cannot be explained without the influence of titanite. We therefore show that the saturation of trace element-rich phases in magmas represents a significant geochemical event in the petrogenesis of intermediate to silicic magmas. This has implications for provenance studies that attempt to reconstruct bulk rock compositions from mineral compositions, as the residual melts from which those minerals crystallise can be driven to significantly different compositions from the host magma by late-stage accessory phase crystallisation. [ABSTRACT FROM AUTHOR]

In situ oxygen analysis of garnet in eclogite and related rocks is increasingly being used to probe the composition of subduction fluids. However, in many cases, these samples contain textural signs of both fluid flow and retrograde metamorphism, some of which may take place outside the garnet stability field. In order to test the connection between polymetamorphism and fluid infiltration, rutile rimmed by titanite from high‐grade tectonic blocks of the Franciscan Formation (California, USA) was analysed for oxygen isotope ratios and trace element concentrations. Zirconium concentrations in rutile yield temperatures of ~600°C for eclogite and hornblende eclogite from three well‐studied localities (Junction School, Tiburon and Ward Creek). Rutile trace element concentrations are generally low and consistent with a mafic protolith. Titanite surrounding rutile has inherited much of its trace element content from rutile, and Zr‐in‐titanite temperatures are spuriously high. Titanite in rutile‐free samples (blueschist and eclogite from Jenner beach) have similar compositions suggesting that they were formed at the expense of rutile as well. Oxygen isotope ratios from rutile and titanite in the same sample are fortuitously similar, indicating disequilibrium between these minerals, which formed at different times and temperatures but in equilibrium with the same oxygen reservoir. Rutile in blocks with garnets zoned in oxygen isotopes are generally in equilibrium with the rims rather than the cores. Slow oxygen diffusion in rutile and the low temperatures of formation require that rutile recrystallized after fluid interaction and before blueschist facies metamorphism. External fluid interaction of Franciscan eclogites took place near the peak of metamorphism. [ABSTRACT FROM AUTHOR]

Rutile, titanite, and ilmenite are the most common Ti-bearing minerals in metamorphic rocks. Experimental constraints have shown that titanite is stable at low-grade metamorphic conditions, rutile at high pressure (HP), and ilmenite at high temperature, low pressure (HT-LP) conditions. Yet, petrological evidence suggests that titanite can also be stable at low temperature, HP (LT-HP). This implies that both titanite and rutile can be used to develop proxies to track HP metamorphism, which can have interesting applications. In this study, we have investigated the natural occurrence and chemistry of Ti-bearing minerals in gabbroic rocks and basalts that record different degrees of metamorphism, including LP amphibole-bearing gabbros from the ocean floor (Mid-Atlantic and Indian ridge IODP LEGs) and from an obducted ophiolite (Chenaillet) and HP Alpine metagabbros and metabasalts, including blueschist and eclogite facies rocks from the Western Alps and Corsica. We have performed detailed petrography, Raman spectroscopy and analyzed major and trace elements mineral chemistry using EPMA and LA-ICPMS. We found that rutile is stable at low pressure (< 2 kbar) in ocean-floor amphibole-bearing gabbros, lower than experimental constraints had previously suggested. Rutile is also found in eclogitic metagabbros from the Western Alps and can be chemically distinguished from LP rutile. Blueschist metagabbros from the Western Alps and eclogitic metabasalts from Corsica have titanite stable instead of rutile. While the titanite to rutile transition is pressure- and temperature-dependent, we demonstrate how small variations in bulk-rock Ti/Ca and Ca/Al values within the NCKFMASHTO chemical system may shift their stabilities. High-pressure titanite from these metamafic rocks exhibits La depletion and low La/SmN values in comparison to titanite from amphibolite-facies mafic rocks. La/SmN or Nb together with Yb and V can be used to distinguish HP titanite from titanite formed under other P–T settings. These new systematics can be useful in studies using detrital Ti-bearing minerals to probe the HP metamorphic record through time. [ABSTRACT FROM AUTHOR]

BACKGROUND The compositions of the bulk-rocks are commonly modified by hydrothermal alteration or merely represent the magmatic information of snapshot during evolution. Hence, use of the chemical compositions of bulk-rocks makes it difficult to trace the source and evolution of granitic magmas. The petrogenesis of the granitic rock is therefore difficult to decipher. In the face of these difficulties, an alternative new approach is to trace the magmatic source and evolution by in-situ analyzing elements and isotope compositions of accessory minerals in granitic rocks. This new approach can significantly improve the spatial resolution of the magmatic processes. Titanite (CaTiSiO5) is a common accessory mineral of granitic rocks and contains a large amount of elements, including Al, Fe, Nb, Ta, Zr, Cr, V, Sn in the Ti site, and rare earth elements (REEs) Y, Na, Mn, Pb, U, Th, Sr and Ba in the Ca site. REEs and high field strength elements (HFSEs, i.e., Nb, Ta, Zr, Th and U) in titanite are sensitive to the changes of temperature, pressure, oxygen fugacity (fO2), water fugacity and melt composition. Additionally, titanite has high Nd concentration and low Sm/Nd ratio and is suitable for in-situ Nd isotope analyses. Therefore, titanite is an ideal accessory mineral to be used to investigate the magmatic source and evolution of granitic rocks. OBJECTIVES To trace the magmatic source and evolution, and to decipher the petrogenesis of the granitic rock. METHODS Titanite from mafic microgranular enclave (MME) and hosted granodiorite of the Tongshanling granitic pluton were checked by transmission light and back-scattered electron (BSE). BSE images were performed at the Institute of Geochemistry, Chinese Academy of Sciences (IGCAS) in Guiyang, on carbon-coated, polished epoxy blocks using JSM-7800F field emission scanning electron microscopy (SEM) operated at 20kV accelerating voltage and a beam current of 10nA. Their in-situ major element compositions were analysed by electron probe microanalyzer (EPMA) at IGCAS. An accelerating voltage of 25kV and a probe current of 10nA were applied. Well-characterized Kaersutite (Na, K, Mg, Al, Si, Ca, Mn, and Fe), apatite (F), and rutile (Ti) were used as standards. The trace elements of titanite were analysed in-situ by an Agilent 7900 ICPMS equipped with GeoLasPro 193nm ArF laser ablation system (LA-ICP-MS) at IGCAS. Analytical conditions were as follows: a fluence of 5J/cm2, at a repetition rate of 5Hz and laser spot of 44μm. Ca (determined by EPMA) was chosen as the internal standard and the reference glasses NIST610 and NIST612 were used to calibrate relative element sensitivities. In-situ Nd isotope of titanite were analyzed by a Nu Plasma Ⅲ multi-collector (MC) equipped with RESOlution-155 ArF 193nm laser ablation system (LA-MC-ICP-MS) at IGCAS. Titanite was ablated in a mixture of helium (350mL/min) and nitrogen (2mL/min) atmosphere using the following parameters: 30s baseline time, 40s ablation time, 72μm spot size, 6Hz repetition rate and 6J/cm2 energy density. The interference of 144Sm on 144Nd was derived from the 147Sm intensity with a natural 144Sm/147Sm ratio of 0.205484. The mass bias factor of Sm was calculated from the measured isotopic ratio of 144Sm/149Sm and its true value 1.08680. The mass bias of 143Nd/144Nd was normalized to 146Nd/144Nd=0.7129 with an exponential law. The reference materials MAD, Otter Lake, LAP and SAP were chosen as the external standards. RESULTS Titanite grains in the MME, and host granodiorite of the Tongshanling granitic pluton have similar major element compositions. All titanite are characterized by high SiO2 (31.0% to 31.7%), CaO (29.0%-30.0%), TiO2 (30.6%-38.2%), and low Al2O3 (1.81%-5.61%), FeO (0.184%-0.606%), F (0.48%-1.84%) contents. The MnO concentrations vary between 0.024% and 0.066%. The MgO concentrations range from 0.001% to 0.031%. Compositional zoning among single titanite grains were not observed. The crystallo-chemical formulae were calculated on the basis of 5 oxygen atoms. The calculated results indicate that the Al+Fe (apfu) is negatively correlated with Ti (apfu) in all titanite grains. The analysed titanite grains have high rare earth element (REE) contents (67-1498μg/g). The REE were incorporated into titanite lattice by substituting for Ti and Ca site with Al and Fe and the substituted mechanism is (Al, Fe3+)+REE=Ti4++O2-. On the REE patterns, the titanite from granodiorite has REE contents higher than that from MME and shows weak positive or negative Eu anomaly (Eu/Eu* from 0.62 to 1.39). On the contrary, titanite from MME is characterized by Eu positive anomaly (Eu/Eu* from 1.13 to 3.94). These titanite contain high content of HFSEs such as Zr (11.1-536μg/g), Hf (0.639-21μg/g), Nb (306-1489μg/g) and Ta (24.7-109.5μg/g). The variation of Zr/Hf, Nb/Ta and Y/Ho ratios of titanite grains range from 21.0 to 31.5, 10.4 to 13.9 and 27.4 to 35.0, respectively. These trace element ratios are consistent with those of normal crust and are not fractionated. Therefore, the trace elements of titanite were completely controlled by ion radius and charge and not affected by late hydrothermal alteration. Titanite Zr thermometer shows that the temperature of titanite formation is between 762℃ and 963℃. Titanite from MME has homogenous Nd isotope compositions. Their present 144Nd/143Nd ranges from 0.512321 to 0.512675, corresponding to εNd(t) value from -3.5 to -8.9 with an average of -7.2±2.4 (N=6). Titanite from granodiorite overall have 144Nd/143Nd ratio ranging from 0.512269 to 0.513399. Their time-corrected initial εNd(t) value vary between -5.4 and -9.9 with an average of -6.9±2.4 (N=5). All titanite grains have negative initial Nd isotopic compositions, which is consistent with the evolution trend of Nd isotopes of the middle-lower continental crust of South China. CONCLUSIONS Titanite grains in the MME and host granodiorite of the Tongshanling granitic pluton show little or no intra-grain concentric zoning in BSE images and display similar element and isotopic geochemical characteristics. Crystal chemical exerts a first-order control on elemental compositions of titanite. Titanite survived during hydrothermal alteration and faithfully recorded the information of granitic melts. The granitic melts of the Tongshanling are characterized by high temperature and oxygen fugacity. Granodiorites from the Tongshanling pluton were probably formed by the amphibole-dehydration melting of a mafic source in the middle-lower crust beneath South China.

The last decade has seen a marked increase in U‐Th‐Pb petrochronological studies focused on titanite and apatite. This has motivated the need for detailed, phase‐specific method development and well‐characterised reference materials with a wide variety of ages and chemical compositions. This study presents new U‐Th‐Pb isotope and major‐, minor‐ and trace‐element mass fraction data for ten titanite and five apatite reference materials based on integrated EPMA, LA‐ICP‐MS and isotope‐dilution (ID) multi‐collector (MC)‐ICP‐MS characterisation. Cross‐comparison of EPMA and LA‐ICP‐MS data for the same titanite reference material suite demonstrates that careful selection of EPMA primary reference materials is necessary to minimise inaccuracies. We further identify a significant X‐ray interference when measuring low Ce abundances in Ti‐bearing phases and outline a method for its correction. New ID‐MC‐ICP‐MS and LA‐ICP‐MS data suggest tri‐concordance (defined as concordant ages for the 238U‐206Pb, 235U‐207Pb and 232Th‐208Pb decay systems) of the MKED‐1 titanite reference material and demonstrate the reproducibility of 208Pb/232Th measurements in some secondary titanite reference materials. Integration of 208Pb/232Th results with U‐Pb geochronology provides a meaningful tool to help interpret complex U‐Th‐Pb isotopic age spectra. We provide example applications of 208Pb/232Th LA‐ICP‐MS measurements toward interpreting Archaean titanite ages from the Acasta Gneiss Complex, Northwest Territories, Canada. [ABSTRACT FROM AUTHOR]

Titanite CaTiO(SiO 4):Eu3+ were synthesized by a solvothermal-calcination method and an improved high-temperature solid-state synthesis method. Their structure, luminescence properties and photocatalytic propoties were comparatively studied in detail. It was found that CaTiO(SiO 4):Eu3+ synthesized by the two methods belong to two different types of crystalline and each of them has its own advantages and disadvantages. Titanite synthesized by solvothermal-calcination method has rough and porous surface morphology, larger BET, and smaller crystallite size, which result in a weaker luminescence intensity than the one synthesized by high-temperature solid-state method. But in the experiment of photocatalysis, all these disadvantages are turned into advantages. In addition, the high temperature process also increases the symmetry of Eu3+ occupation and leads to many surface traps, which result in a less red color and a shorter fluorescence life than solvothermal synthesized titanite. We hope that this comparative study will extend the applications and research ideas of titanite. [Display omitted] [ABSTRACT FROM AUTHOR]

Quantifying the timing and conditions of ductile deformation is essential for quantitative models of lithospheric deformation. Yet, directly constraining these variables and documenting how they change during a single deformation event remain difficult. We present titanite microstructural, zoning, trace‐element, and U‐Pb data from

Titanite is a widespread accessory mineral in igneous, metamorphic, and hydrothermal rocks, but few comply with gem-grade requirements. Previous studies on Moroccan titanite focused on elementary composition and U-Pb dating. In this study, two gem-grade titanites (MA-1 and MA-2) from the Moroccan Central High Atlas were investigated through gemological and chemical studies, including infrared spectrum, Raman spectrum, SEM-EDS, and LA-ICP-MS. Two titanite samples are yellow, transparent–translucent with a greasy luster, 3.5 and 2.5 mm long. MA-1 and MA-2 have similar gemological properties, the refractive index (RI) is beyond the range of the refractometer (>1.78), the specific gravity (SG) values fall in the range of 3.52~3.54 and both are inert to short-wave and long-wave UV radiation. The spectral characteristics have high consistency with the RRUFF database. The major elements’ composition shows a negative correlation between Al, Fe, V, and Ti, suggesting the titanites underwent substitutions such as (Al, Fe3+) + (F, OH) ↔ Ti + O. The titanite samples, characterized by a low abundance of REE (802~4088 ppm) and enriched in LREE, exhibit positive Eu (δEu: 1.53~7.79) and Ce (δCe: 1.08~1.33) anomalies, indicating their formation in a hydrothermal environment with low oxygen fugacity. The 238U/206Pb and 207Pb/206Pb ratios of the titanites yield lower intercept ages of 152.6 ± 2.2 and 151.4 ± 5.3 Ma (1s), consistent with their weighted average 206Pb/238U ages of 152.3 ± 2.0 and 150.7 ± 3.2 Ma (1s) respectively. The results of U-Pb dating are matched with the second main magmatic activities in the High Atlas intracontinental belt of Morocco during the Mesozoic to Cenozoic period. Moreover, the two titanite samples have almost no radiational damage. All the results show that the titanite from High Atlas, Morocco, has the potential to be a reference material for LA-ICP-MS U–Pb dating, but further experiments are needed to be sure.

BACKGROUND: The compositions of the bulk-rocks are commonly modified by hydrothermal alteration or merely represent the magmatic information of snapshot during evolution. Hence, use of the chemical compositions of bulkrocks makes it difficult to trace the source and evolution of granitic magmas. The petrogenesis of the granitic rock is therefore difficult to decipher. In the face of these difficulties, an alternative new approach is to trace the magmatic source and evolution by in-situ analyzing elements and isotope compositions of accessory minerals in granitic rocks. This new approach can significantly improve the spatial resolution of the magmatic processes. Titanite (CaTiSiO5) is a common accessory mineral of granitic rocks and contains a large amount of elements, including Al, Fe, Nb, Ta, Zr, Cr, V, Sn in the Ti site, and rare earth elements (REEs) Y, Na, Mn, Pb, U, Th, Sr and Ba in the Ca site. REEs and high field strength elements (HFSEs, i. e., Nb, Ta, Zr, Th and U) in titanite are sensitive to the changes of temperature, pressure, oxygen fugacity ( fO2 ), water fugacity and melt composition. Additionally, titanite has high Nd concentration and low Sm / Nd ratio and is suitable for in-situ Nd isotope analyses. Therefore, titanite is an ideal accessory mineral to be used to investigate the magmatic source and evolution of granitic rocks. OBJECTIVES: To trace the magmatic source and evolution, and to decipher the petrogenesis of the granitic rock. METHODS: Titanite from mafic microgranular enclave ( MME) and hosted granodiorite of the Tongshanling granitic pluton were checked by transmission light and back - scattered electron ( BSE). BSE images were performed at the Institute of Geochemistry, Chinese Academy of Sciences ( IGCAS) in Guiyang, on carbon - coated, polished epoxy blocks using JSM-7800F field emission scanning electron microscopy (SEM) operated at 20kV accelerating voltage and a beam current of 10nA. Their in-situ major element compositions were analysed by electron probe microanalyzer (EPMA) at IGCAS. An accelerating voltage of 25kV and a probe current of 10nA were applied. Well-characterized Kaersutite (Na, K, Mg, Al, Si, Ca, Mn, and Fe), apatite (F), and rutile (Ti) were used as standards. The trace elements of titanite were analysed in -situ by an Agilent 7900 ICPMS equipped with GeoLasPro 193nm ArF laser ablation system (LA-ICP-MS) at IGCAS. Analytical conditions were as follows: a fluence of 5J/ cm², at a repetition rate of 5Hz and laser spot of 44μm. Ca (determined by EPMA) was chosen as the internal standard and the reference glasses NIST610 and NIST612 were used to calibrate relative element sensitivities. In - situ Nd isotope of titanite were analyzed by a Nu Plasma Ⅲ multi - collector ( MC) equipped with RESOlution-155 ArF 193nm laser ablation system ( LA-MC-ICP -MS) at IGCAS. Titanite was ablated in a mixture of helium (350mL / min) and nitrogen (2mL / min) atmosphere using the following parameters: 30s baseline time, 40s ablation time, 72μm spot size, 6Hz repetition rate and 6J/ cm² energy density. The interference of 144Sm on 144Nd was derived from the 147Sm intensity with a natural 144Sm / 147Sm ratio of 0. 205484. The mass bias factor of Sm was calculated from the measured isotopic ratio of 144Sm / 149Sm and its true value 1. 08680. The mass bias of 143Nd / 144Nd was normalized to 146Nd / 144Nd = 0. 7129 with an exponential law. The reference materials MAD, Otter Lake, LAP and SAP were chosen as the external standards. RESULTS: Titanite grains in the MME, and host granodiorite of the Tongshanling granitic pluton have similar major element compositions. All titanite are characterized by high SiO2 ( 31. 0% to 31. 7%), CaO ( 29. 0% - 30. 0%), TiO2 (30. 6%-38. 2%), and low Al2O3 (1. 81% -5. 61%), FeO (0. 184% -0. 606%), F (0. 48% - 1. 84%) contents. The MnO concentrations vary between 0. 024% and 0. 066%. The MgO concentrations range from 0. 001% to 0. 031%. Compositional zoning among single titanite grains were not observed. The crystallo - chemical formulae were calculated on the basis of 5 oxygen atoms. The calculated results indicate that the Al+Fe (apfu) is negatively correlated with Ti ( apfu) in all titanite grains. The analysed titanite grains have high rare earth element (REE) contents (67-1498μg / g). The REE were incorporated into titanite lattice by substituting for Ti and Ca site with Al and Fe and the substituted mechanism is (Al,Fe3+ )+REE = Ti4+ +O2- . On the REE patterns, the titanite from granodiorite has REE contents higher than that from MME and shows weak positive or negative Eu anomaly (Eu / Eu ∗ from 0. 62 to 1. 39). On the contrary, titanite from MME is characterized by Eu positive anomaly (Eu / Eu ∗ from 1. 13 to 3. 94). These titanite contain high content of HFSEs such as Zr ( 11. 1 - 536 μg / g), Hf (0. 639 - 21μg / g), Nb (306 - 1489μg / g) and Ta (24. 7 - 109. 5μg / g). The variation of Zr/ Hf, Nb / Ta and Y/ Ho ratios of titanite grains range from 21. 0 to 31. 5, 10. 4 to 13. 9 and 27. 4 to 35. 0, respectively. These trace element ratios are consistent with those of normal crust and are not fractionated. Therefore, the trace elements of titanite were completely controlled by ion radius and charge and not affected by late hydrothermal alteration. Titanite Zr thermometer shows that the temperature of titanite formation is between 762℃ and 963℃ . Titanite from MME has homogenous Nd isotope compositions. Their present 144Nd / 143Nd ranges from 0. 512321 to 0. 512675, corresponding to εNd(t) value from -3. 5 to -8. 9 with an average of -7. 2±2. 4 (N= 6). Titanite from granodiorite overall have 144Nd / 143Nd ratio ranging from 0. 512269 to 0. 513399. Their time-corrected initial εNd(t) value vary between -5. 4 and -9. 9 with an average of -6. 9±2. 4 (N= 5). All titanite grains have negative initial Nd isotopic compositions, which is consistent with the evolution trend of Nd isotopes of the middle - lower continental crust of South China. CONCLUSIONS: Titanite grains in the MME and host granodiorite of the Tongshanling granitic pluton show little or no intra - grain concentric zoning in BSE images and display similar element and isotopic geochemical characteristics. Crystal chemical exerts a first-order control on elemental compositions of titanite. Titanite survived during hydrothermal alteration and faithfully recorded the information of granitic melts. The granitic melts of the Tongshanling are characterized by high temperature and oxygen fugacity. Granodiorites from the Tongshanling pluton were probably formed by the amphibole-dehydration melting of a mafic source in the middle-lower crust beneath South China. [ABSTRACT FROM AUTHOR]

There are rich deposits of rare earth elements (REE) in the Murmansk region, Russia (approximately 14 194 kt of REE2O3). At the moment only one of REE deposits are being extracted and processed, the Lovozero Loparite deposit. The main purpose of this article is to estimate the expected value of existing REE resources in the Murmansk region and to make an overview on actual technologies for the extraction and processing of REE from ore minerals. Based on these data, the authors propose a direction for the development of REE industry in the region, namely extraction of REE from minerals already mined (apatite of the Khibiny deposits and baddeleyite of the Kovdor deposit); optimisation or development of mineral processing technologies of eudialyte (the Lovozero Eudialyte deposit) and perovskite (the Afrikanda deposit); carrying out exploration works at the Keivy Zr-REE ore occurrences and developing processing and technologies for these ores. [ABSTRACT FROM AUTHOR]

Varietal studies of sedimentary provenance use the properties of individual minerals or mineral groups. These are recorded as lists of numerical tables that can be difficult to interpret. Multidimensional Scaling (MDS) is a popular multivariate ordination technique for analyzing other types of provenance data based on, for example, detrital geochronology or petrography. Applying MDS to varietal data would allow them to be treated on an equal footing with those other provenance proxies. MDS requires a method to quantify the dissimilarity between two samples. This paper introduces three ways to do so. The first method ("treatment‐by‐row") turns lists of (compositional) data tables into lists of vectors, using principal component analysis. These lists of vectors can then be treated as "distributional" data and subjected to MDS analysis using dissimilarity measures such as the Kolmogorov‐Smirnov statistic. The second method ("treatment‐by‐column") turns lists of compositional data tables into multiple lists of vectors, each representing a single component of the varietal data. These multiple distributional data sets are subsequently subjected to Procrustes analysis or 3‐way MDS. The third method uses the Wasserstein‐2 distance to jointly compare the rows and columns of varietal data. This arguably makes the best use of the data but acts more like a "black box" than the other two methods. Applying the three methods to a detrital titanite data set from Colombia yields similar results. After converting varietal data to dissimilarity matrices, they can be combined with other types of provenance data, again using Procrustes analysis or 3‐way MDS. Plain Language Summary: The source of modern or ancient sediment can be determined by examining either the overall characteristics of the sediment or the chemical composition of individual sediment particles. With the help of recent analytical advancements, geologists can now analyze the complete chemical makeup of single grains of sand or silt. These types of data sets, known as "varietal" data sets, have the ability to uncover differences between sediments that are not visible through traditional methods. However, varietal data are incompatible with the statistical methods that geologists typically use to determine the origin of sediment. This paper addresses this issue by presenting three methods for quantifying the differences between varietal data sets, which is a crucial step in any further statistical analysis. Testing these methods on a varietal data set from Colombia shows similar outcomes. By using the techniques described in this paper, varietal data can now be combined with other conventional methods for determining sediment origin. Key Points: Varietal data are defined as lists of compositional tablesGiven an appropriate dissimilarity measure, varietal data can be subjected to multidimensional scalingThis paper introduces three ways to quantify the pairwise dissimilarity of varietal data [ABSTRACT FROM AUTHOR]

Textural and compositional variations in titanite constrain the roles of magma mixing and hydrothermal alteration in two plutons in central Utah: the Jurassic Notch Peak and the Oligocene Little Cottonwood stocks. In the Notch Peak intrusion, magmatic titanite grains usually have oscillatory zones combined with BSE-bright sector zones, in some cases surrounding simple unzoned cores. These grains are frequently overprinted by hydrothermal titanite with low concentrations of high field strength elements (HFSE). Magmatic titanite has an average δ18O of 6.0‰ and post-magmatic titanite is 6.2‰, as analyzed by SIMS. Average Zr-in-titanite temperatures are also similar, with 718 °C for magmatic and 711 °C for hydrothermal titanite. These observations indicate simple magmatic growth, followed by hydrothermal alteration by magmatic fluids. Titanite in aplite dikes and sills has lower concentrations of all trace elements except F. Many titanite grains in the aplites have late overgrowths of high-Fe titanite. This high-Fe titanite has δ18O of 6‰ and an average Zr-in-titanite temperature of 718 °C and likely precipitated from a last flush of exsolved magmatic water enriched in Cl and Fe. Titanite in the Little Cottonwood stock typically has distinct patchy cores with rounded and embayed ilmenite inclusions. Mafic enclaves have abundant titanite that is similar in texture and δ18O (5.1‰) to titanite in the host (δ18O = 4.9‰), but it has a slightly higher average Zr-in-titanite temperature (731 vs. 717 °C). The patchy cores in the enclaves have the highest average Zr-in-titanite temperature (759 °C) and distinctive REE patterns. The textural and compositional data indicate that a hotter, more reduced, ilmenite-bearing mafic magma mixed into an oxidized felsic magma, destabilizing existing ilmenite and allowing crystallization of titanite. In the granodiorite and in the enclaves, hydrothermal growth of titanite is evidenced by distinct narrow rims as well as anhedral titanite that grew between sheets of chloritized biotite. Secondary hydrothermal titanite typically has lower concentrations of most HFSE, but is relatively enriched in F, Mg, Mo, and U, and it has higher Nb/Ta and lower Th/U ratios. Post-magmatic titanite also has strikingly different REE patterns than magmatic titanite, including the absence of pronounced Eu anomalies and lower REE abundances. These chemical features are controlled by element solubilities in aqueous fluids. In most cases, hydrothermal titanite has δ18O values similar to magmatic titanite, indicating alteration and recrystallization from exsolved magmatic fluids. The involvement of meteoric water with low δ18O is evident locally; individual spots have δ18O as low as 1.7‰ in the Little Cottonwood stock. Titanite compositions and textures provide important insights into the origins of granitic rocks and can be used to distinguish separate batches of magma, gauge the evolution of magmatic rocks, assess mixing processes, and infer compositions of mixing components. Because titanite also forms hydrothermally, it retains hints about the composition, temperature, and oxygen fugacity of the hydrothermal fluids and reveals details about titanite-forming reactions. However, the Al-in-titanite geobarometer does not yield realistic pressures of crystallization and the use of titanite as a geochronometer is compromised by the development of U-rich hydrothermal titanite. [ABSTRACT FROM AUTHOR]

The formation of titanite coronae after rutile is common in retrograde high‐ to ultrahigh‐pressure meta‐mafic rocks, which provides a good opportunity to address the geochemical behavior of HFSE in crustal environments. In the Sumdo eclogite, titanite occurs either as a corona around rutile grains or as semi‐continuous veins cross‐cutting the major foliation, whereas rutile grains occur either as inclusions in garnet or omphacite or as a relict core surrounded by titanite. Textural relationships and trace elements characteristics of rutile and titanite with different occurrences indicate that both minerals preferentially incorporate Nb and Hf over Ta and Zr in aqueous fluid. Moreover, the breakdown of omphacite and epidote could release substantial amounts of aqueous fluids enriched in Ca, Si, Fe and REE, which would react with rutile to form titanite coronae and veins. During this process, water‐insoluble elements, like HFSE and HREE, behave like mobile elements, but they do not migrate substantially out of the system, instead, tending to react in situ. This suggests that the aqueous fluids released during the retrograde metamorphic reactions in mafic rocks could not substantially transfer fluid‐immobile elements into the overlying mantle wedge in subduction environments. [ABSTRACT FROM AUTHOR]

Carbonatites and alkaline rocks often exhibit a close spatial association with Nb and rare earth elements (REE) mineralization. Petrological and experimental studies suggest that carbonated and alkaline silicate melts can be formed directly through low-degree partial melting of a carbonate-bearing mantle. Alternatively, some propose that fractional crystallization followed by liquid immiscibility from mantle-derived magmas could be a viable model for the formation of carbonatites and alkaline rocks. In this study, samples from ultramafic to alkaline rocks and carbonatites in the Shangzhuang P-REE deposit, Western China are analyzed to investigate this issue. The complexes consist of biotite clinopyroxenite, fluorapatite-rich biotite clinopyroxenite, and calcite-K-feldspar-amphibole-rich clinopyroxenite, interspersed with minor syenite and carbonatite dykes. These suites of rocks exhibit similar ages and Nd isotopic characteristics, indicating their derivation from a common magma source. Field, petrological, geochemical, and Ti isotopic investigations reveal the parental ultramafic melts (with high Mg#, low HFSE, and chondritic δ49Ti values) undergo a differentiation process into carbonate- and alkaline-rich ultramafic silicate melts (enriched in REEs, HFSE and Fe). These carbon- and alkaline-rich melts then formed immiscible carbonatitic- (high REE and negative δ49Ti values of −1.78 to −0.49 ‰) and alkaline silicate-melts (high Nb and δ49Ti values of +0.18 to +0.62 ‰). The enrichment of REE and Nb in the system is attributed to magmatic crystallization differentiation and subsequent liquid immiscibility. This process resulted in the enrichment of REE in carbonatites, whereas alkaline rocks show a higher enrichment in Nb. This study provides a possible mechanism to explain the genetic linkage between carbonatites and alkaline rocks that is likely applicable to similar rock suites worldwide. [Display omitted] [ABSTRACT FROM AUTHOR]

Titanite is often used to describe the path of igneous, metamorphic, and hydrothermal processes. Therefore, titanite can unravel the multistage magmatic and post-magmatic evolution of granitoids. In this study, we present a comprehensive study of the ca. 2.57–2.51 Ga Closepet Batholith in the Dharwar Craton of southern India using titanite. This granitoid body provides a unique opportunity as various structural levels of the batholith are continuously outcropping. The textural and geochemical studies of titanite, supported by U Pb isotopic dating, allowed us to distinguish five generations of magmatic and hydrothermal titanite. Three types of magmatic titanite demonstrate stage-growth crystallization (type I) and a change from reduced, high-temperature (type II) to oxidised, low-temperature conditions (type III). Hydrothermal titanite is recorded as altered titanite with zoned to patchy textures and secondary fractures and veinlets (type IV) and titanite inclusions within biotite (type V). Hydrothermal titanite (type IV) shows depletion in rare earth elements and high-field strength elements, indicating mobilization of those elements by a fluid. U Pb dating by LA-ICP-MS of magmatic titanite type I yielded ages of ca. 2.5 Ga, consistent with the timing of formation of the Closepet Batholith. The relationship between titanite textures and chemistry indicates that titanite serves as a recorder of the multistage magmatic and post-magmatic evolution of the Closepet Batholith. In addition, our study shows that hydrothermal activity affected a large area, with fluids circulating over long distances within the upper structural levels of the Closepet Batholith. • The Closepet Batholith formed during multistage processes. • Titanite is a recorder of the multistage magmatic and post-magmatic evolution. • Textural and chemical signatures of titanite allow provide insight into its origin. [ABSTRACT FROM AUTHOR]

Titanite is a valuable tool for studying polymetamorphism and understanding the evolution of orogenic belts as it potentially records different stages of metamorphic evolution. The combination of geochronology and Zr-in-titanite geothermometry has been widely used in petrochronology studies. However, there is ongoing debate regarding the significance of ages and temperatures obtained from titanite. Here, we conducted the first integrated titanite, zircon, and apatite U Pb study, along with Zr-in-titanite geothermometry, on calc-silicate rocks from a polymetamorphic complex of the central Dom Feliciano Belt (Western Gondwana). Our aim was to investigate the impact of various metamorphic events on titanite grains. We carried out a geochronological, geochemical, and petrographic analysis of a calc-silicate sequence of the Passo Feio Complex, which was intruded by the Caçapava do Sul Granitic Complex (CSGC). The metamorphic complex experienced regional, contact, and hydrothermal metamorphism during the Neoproterozoic, but the ages and conditions of these metamorphic events remain widely debated. U Pb analyses on over one hundred titanite grains from a K-feldspar-diopside schist revealed three distinct titanite populations. The older group, dated at 639 ± 3/7 Ma (2s; n = 19), was associated with the regional metamorphism event (M 1), likely initiated by the primary collision of the Dom Feliciano Belt. The intermediate group exhibited an age of 596 ± 1/6 Ma (2s; n = 91). Given the presence of high-K magmatism and a carbonatite intrusion in the study area, producing zircon U Pb ages around 600 Ma, this group was associated with contact metamorphism (M 2), belike influenced by these intrusive igneous activities. The youngest titanite population showed an age of 566 ± 3/6 Ma (2s; n = 6), which closely aligns, within analytical error, with the age of 561 ± 1/6 Ma (2s; n = 46) obtained from U Pb dating on apatite sourced from a diopside-phlogopite schist. The younger ages observed in both titanite and apatite are attributed to alterations resulting from interactions with hydrothermal fluids (M 3) during the cooling phase of the CSGC. Chemical analyses conducted with an electron microprobe assessed the Zr concentrations in fifty titanite grains, examining both bright and dark zones observed in back-scattered electron images. The lowest temperature recorded among the 50 grains was 629 °C, which corresponds to dark BSE zones. In the light zones, the minimum temperature was 639 °C. While temperatures estimated using the Zr content in titanite may not correspond precisely with U Pb ages, combining titanite ages with those from other accessory minerals like zircon and apatite, along with microstructural analysis, can provide a more comprehensive understanding of orogenic belt evolution. • Regional, contact, and hydrothermal metamorphism from 639 to 561 in the Western Gondwana (Central Dom Feliciano Belt). • Three metamorphic events recorded in titanite grains. • Titanite, apatite and zircon track polymetamorphism in the Passo Feio Complex. [ABSTRACT FROM AUTHOR]

Besides radiation resistance, thermal recovery of radiation damage provides another critical criterion to evaluate the host phase for immobilizing high-level waste (HLW) produced by nuclear plants. Despite the increasing investigations, a comprehensive atomic-scale understanding remains elusive on thermal annealing of radiation damage in ceramics. Here, using in situ heating high-resolution transmission electron microscopy, we investigate the thermal annealing of radiation damage in natural metamict titanite (CaTiSiO 5) caused by a high alpha decay dose from the incorporated U and Th during the geologic time. The recovery of the fully amorphous titanite precursor starts at 456 ℃ from the appearances of monoclinic nanoparticles 2–5 nanometers wide, and more nanoparticles form as the temperature gradually increases. At 1000 ℃, the amorphous phase recovers through epitaxial growth with titanite nanoparticles as templates. This study provides information for a unit-cell-scale understanding of the thermal stability of radiation damage in titanite-based ceramics, having significance for immobilizing HLW. • Thermal recovery of totally amorphous titanite was investigated by in situ heating HRTEM. • The recovery of amorphous titanite starts from the appearance of nanoparticles. • The epitaxial growth with a titanite nanoparticle being the template was observed in real time. [ABSTRACT FROM AUTHOR]

The Khan River (Namibia) and Bear Lake (Canada) titanites are investigated as potential reference materials (RM) for LA‐ICP‐MS applications. The Bear Lake titanite is texturally and compositionally homogeneous. The Khan River titanite is texturally heterogeneous and characterised by variable trace element compositions and total rare earth element contents. However, both titanites have consistent U‐Pb and Nd‐isotope ratios. U‐Pb isotope dilution‐thermal ionisation mass spectrometry analyses yielded Pbc‐uncorrected intercept ages of 516.3 ± 1.3 Ma (2s, n = 5, MSWD = 2.4) and 1067.81 ± 0.74 Ma (2s, n = 4, MSWD = 0.35) for Khan River and Bear Lake titanites, respectively. Multiple U‐Pb LA‐SF/MC‐ICP‐MS analyses gave consistent Pbc‐uncorrected intercept ages for both, Khan River (517 ± 1/5 Ma, 2s, n = 262, MSWD = 1.5) and Bear Lake (1070 ± 1/11 Ma, 2s, n = 325, MSWD = 0.88). U‐Pb SHRIMP analyses on the same material returned identical (within uncertainty) ages. Khan River and Bear Lake gave internally consistent solution MC‐ICP‐MS 143Nd/144Nd ratios of 0.511587 ± 0.000027 (2s, n = 2) and 0.512321 ± 0.000004 (2s, n = 2), respectively. The 143Nd/144Nd ratios via solution‐MC‐ICP‐MS and LA‐ICP‐MS all agree within uncertainty and suggest that both titanites can be used as RMs for Nd‐isotope analyses. [ABSTRACT FROM AUTHOR]

The metamorphic reworking of mineralized pegmatites during orogenesis remains unclear, making the genesis and the tectonomagmatic significance of pegmatite mineralization obscure. This study demonstrates the multiple utilities of titanite geochemistry in establishing the Caledonian metamorphic evolution of the world's largest intra-plutonic Nb-Y-F pegmatites in the Paleoproterozoic host rocks in Tysfjord, Northern Norway. A combination of titanite-specific barometry, Zr-in-titanite thermobarometry, and titanite U-Pb geochronology yields peak metamorphism of ∼12 kbar and 730–750 °C at ∼410 Ma for the host rocks and the largest metamorphosed Paleoproterozoic pegmatite (meta -pegmatite) in the region. In relation to published U-Pb ages of 410–400 Ma for other regional meta -pegmatites, interpreted as Caledonian overprinting here, we argue that the Paleoproterozoic pegmatite protoliths have undergone metamorphism analogous to the host rocks, which was caused by allochthonous nappe stacking late in the Caledonian collisional orogeny (∼440–400 Ma). Published formation ages of ∼400–380 Ma for the regional undeformed pegmatites are 10–30 Ma younger than the peak metamorphism, supporting an anatectic link to the Caledonian post-collisional extension. The Caledonian orogeny led to strong shearing of preexisting pegmatite bodies and resetting of trace elements and U-Pb isotopic systems of the constituent minerals via mineral re-crystallization, inheritance of Pb isotopic components, and element diffusion. This cautions against the interpretation of meta -pegmatite-derived ages and geochemical information in tectonomagmatic terranes without detailed textural investigation. [ABSTRACT FROM AUTHOR]

Marble in the supracrustal rocks of the Lewisian Complex, Tiree, includes chlorine-bearing amphiboles, chlorine-rich apatite, sulphur-rich scapolite, albite and phlogopite, all of which are regarded as evidence for evaporites in other metamorphosed sequences. Titanite yields U–Pb ages of ∼1.6 Ga, i.e. late Laxfordian, which excludes a younger imprint of sodium metasomatism. Traces of anhydrite, and isotopically heavy pyrite, also indicate deposition from seawater. Elsewhere in the Hebrides, tourmaline in Lewisian Complex marbles may represent seafloor exhalative deposits. Combined, the evidence suggests Lewisian Complex supracrustal marbles formed in an evaporative environment, like other Palaeoproterozoic successions across the North Atlantic region. [ABSTRACT FROM AUTHOR]

As a common Ca‐ and Ti‐ bearing silicate mineral in many types of hydrothermal deposits, titanite usually contains high concentrations of trace elements. Its mineral chemistry and U–Pb isotope can reveal the physicochemical conditions and geochronology of the ore‐forming systems. In this contribution, we present a detailed study on titanite which precipitated during the Fe mineralization in the Duotoushan deposit. Due to coexistence with hydrothermal minerals, low Th/U ratios (0.02–0.3), and depletion in rare earth elements (REE), all the studied titanites are classified into a hydrothermal group. The negative correlation between [REE3+ + (Al, Fe)3+] and [Ca2+ + Ti4+] indicates that REE mainly entered the lattice of titanite via the mechanism of substitution. In addition, titanite grains are characterized by HREE, Zr, and Nb enrichments with LREE depletion, suggesting that the complexation of F− at neutral to alkaline pH conditions may have caused the fractionation of REE. At Duotoushan, the titanite grains coexist with quartz, epidote, amphibole, and magnetite, and exhibit positive Eu anomalies (δEu = 1.04–1.31) but lack Ce anomalies, indicating that ore‐forming fluids may have been derived from a relatively low oxygen fugacity and high fH2O environment. Titanite yielded an in‐situ U–Pb lower‐intercept age of 307.2 ± 4.8 Ma (MSWD = 0.97), consistent with the syn‐ore amphibole 40Ar‐39Ar plateau age (305 ± 6 Ma). Since the mineralization ages are obviously younger than country rocks, the previous syn‐sedimentary ore‐forming model for Duotoushan Fe–Cu mineralization can be excluded. Integrating the characteristics from ore deposit geology, periods of mineralization events, and spatial–temporal distribution of magmatism, we proposed that the Duotoushan Fe–Cu mineralization event may be linked with a hidden granite in its orefield. [ABSTRACT FROM AUTHOR]

With the development of mineral testing technology and ore deposit geochemistry, titanite has become a hot topic in the study of accessory minerals. Two large-grained titanite crystals from Mogok, Myanmar, were used for a detailed study. In this study, the standard gemmological properties and spectral characteristics of titanite crystals were obtained by Fourier transform in-frared, micro ultraviolet-visible-near-infrared and Raman spectroscopy, respectively, which pro-vide a full set of data. Mineral major and trace elements were analysed using Electron-Probe Mi-croAnalysis (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The purpose of this study is to report spectral characteristics and major and trace elements of Mogok, Myanmar, in order to find new potential titanite standard samples. The two titanite crystals have similar major element compositions, and both grains have relatively low Al content (0.011–0.014 apfu) and Al/Fe ratios (0.157–0.222), but high Fe content (0.063–0.079 apfu). The two titanite crystals have similar chondrite-normalised rare earth element (REE) patterns with significantly Light Rare Earth Element (LREE) (La–Gd) enrichment and deletion of Heavy Rare Earth Element (HREE) (Tb–Lu). The 238U/206Pb ages of the two titanite samples are 43.5 ± 5.8 Ma and 34.0 ± 4.2 Ma, respectively. Generally, magmatic titanite has a low Al/Fe ratio, metamorphic and hydrothermal titanite crystals have extremely low Th/U ratios close to zero, with flat chondrite-normalised REE patterns or depletions in light REEs relative to heavy REEs. Different genetic types of titanite can be distinguished by the characteristics of major and trace elements. Combined chemical features such as REE differentiation, Al/Fe and Th/U ratios with formation temperature, the analysed titanite samples are considered magmatic-hydrothermal titanites. Their 238U/206Pb ages may indicate a potential stage of magmatic hydrothermal conversion. [ABSTRACT FROM AUTHOR]

The uranium-lead isotope method is used to date titanites from granitoids of the Ros’-Tikych megablock of the Ukrainian Shield (middle reaches of the Ros’ river, below Bila Tserkva). Their isotopic behavior is analyzed along with published results, of other titanites found in crystalline rocks of the Ukrainian Shield. Titanites of granitoids from the Ros’-Tikych megablock contain impurity lead and this leads to an abnormal isotopic composition. The overestimation in age values calculated by methods that do not require correction for ordinary lead (method normalized, agreed differences and the slope of the regression line on the graph in the coordinates 207Pb/204Pb — 206Pb/204Pb) is up to several tens of millions of years, compared to, calculated on the model of Ahrens-Wetherill. The influence of impurity lead of anomalous isotopic composition on the distortion of the calculated values of the isotopic age, in the ratio 207Pb/206Pb is modeled. It was found that the entry into the isotope system, 2.0 billion years old, of ordinary lead with a modern isotopic composition, even with a ratio of impurity lead to radiogenic lead 1 : 1, will reduce the age by 207Pb/206Pb by only 4 million years. Significantly greater distortions (overestimations) of the isotopic ages is will be caused by impurity lead, in the isotopic composition of which there is an ancient (for example, 500 million older than the age of crystallization of titanite) radiogenic lead. Thus, when the ratio share of impurity lead is 20%, the overestimation of age is more than 50 million years, and it reaches 235 million years for at a ratio of 1 : 1 (50%). The numerical values of the isotopic age will be even more inflated at the ratio of 207Pb/206Pb in cases when impurity lead contains radiogenic lead of older age, even with a smaller share of it in the composition of impurity lead. [ABSTRACT FROM AUTHOR]

As a result of isotope-geochemical study, the age data (U-Pb method, ID-TIMS) of titanite from the first phase granites of the Belokurikhinsky granite massif, Gorny Altai, were obtained for the first time. The concordant value of the titanite age of 255 ± 2 Ma coincides within the margin of error with the previously published results of dating micas from granites of the second and third phases of the Belokurikha massif by the Ar-Ar method (250 ± 3 Ma). At the same time, the results of dating differ significantly from the previously published age values for the granites of the Belokurikha massif (232 ± 5 Ma, U-Pb method for the monofraction of zircon grains; 245 ± 8 Ma, Rb-Sr method for the whole rocks). Therefore, there is every reason to narrow the time interval of the formation of the Belokurikha granite massif to 255–250 Ma. The study of the trace element composition of titanite by SIMS demonstrated their zonal structure. The central part of the titanite grain differs from the rim by a noticeably higher content of REE, Cr, Y, and Nb. The content of V, Zr and Ba decreases to a lesser extent towards the rim, the content of Sr and U remains constant. At the same time, the REE distribution spectra in the central and rim parts are conformal to each other, having a convex spectrum for LREE and a concave one for HREE. Titanite is characterized by a negative Eu-anomaly, the depth of which decreases to the rim of the grain. A negative Eu-anomaly indicates the co-crystallization of titanite and plagioclase. The REE distribution spectra in titanite from the Belokurikha massif correspond to the characteristics of a typical magmatic titanite from granitoids and differ significantly from the distribution spectra in metamorphic titanite.

• New petrographic and geochemical results of the Bingo alkaline-carbonatite complex. • First emplacement age of the Bingo ijolite using U-Pb titanite geochronology. • First direct age-dating of tropical lateritization via U-Pb geochronology of pyrochlore. This study presents petrographic, whole-rock geochemical, stable isotope (C-O) and U-Pb geochronological data for a suite of carbonatite, nepheline syenite and ijolite from the Bingo complex. The Bingo alkaline-carbonatite complex is located within the western branch of the East African Rift System (EARS) in the Democratic Republic of Congo (DRC). The carbonatites are petrographically classified into calcite and magnetite-calcite carbonatite but have similar geochemical compositions. The ∑REE vary from 960 to 2400 ppm and the La N /Yb N ratios fall within the spectrum of 20 to 145. Calcite stable isotope compositions, δ13C (V-PDB) (−3.51 to −3.87 ‰) and δ18O (V-SMOW) (+12.12 to + 13.70 ‰), plot within the primary igneous carbonatite field and therefore reflect carbonated mantle melts. Based on similarity of geochemical trends between the carbonatite and the alkaline silicate suite, such as negative anomalies in Th, Ta, Pb, Zr, Ti and positive anomalies in Ba, Sr, La and Nb, we suggest that carbonatite and alkaline rocks could have been generated from a carbonated mantle source through extensive fractional crystallization and liquid immiscibility processes. U-Pb titanite dating of the ijolite suggests an emplacement age of 861.5 ± 7.0 Ma during the Neoproterozoic era, consistent with carbonatite magmatism elsewhere along the western branch of the EARS (i.e., Lueshe and Upper Ruvubu Alkaline Complex). This timing is associated with the initial break-up stages of the Rodinia supercontinent, a significant geological event recorded in central Africa during the Neoproterozoic. Additionally, in-situ U-Pb pyrochlore dating of the carbonatite indicates an age of 48.13 ± 0.80 Ma, coupled with a low (radiogenic) 207Pb/206Pb ratio of 0.1554. We discuss three potential interpretations of this anomalous U-Pb age. Firstly, it could represent a primary magmatic crystallization age, implying carbonatite magmatism during the Eocene. A second interpretation is that the age indicates resetting of the U-Pb system due to hydrothermal alteration of the pyrochlore. Thirdly, the pyrochlore could have recrystallized during intense tropical weathering (lateritization). The first and second interpretation are deemed unlikely given the apparent petrogenetic and geochemical relationship between the silicate and carbonatite suites, as well as the fact that this age would predate any recorded rift activity within the western branch of the EARS. Furthermore, the low 207Pb/206Pb ratio points to a highly radiogenic reservoir that is incompatible with a magmatic-hydrothermal source. We thus consider the third option of supergene recrystallization of pyrochlore most likely, possibly from Nb, U and Pb rich fluids released from the overlying weathering profile. As such, supergene pyrochlore might offer a novel approach to determine the absolute age of tropical weathering affecting carbonatites. [ABSTRACT FROM AUTHOR]

The occurrence of the polymetallic Nb layer in the upper Permian Xuanwei Formation in southwest China has been documented extensively. The origin of Nb, as well as other metals like Zr and rare earth elements (REEs), has received much research attention; however, the source of these elements remains enigmatic. In recent studies, an uncommon Nb-rich titanite (CaTiSiO 5) has been discovered in the Emeishan basalts beneath the Xuanwei Formation in the eastern Yunnan–western Guizhou region. However, its origins and genetic relationship to the polymetallic Nb layer remain unclear. In this study, we used in situ microanalytical and U Pb dating techniques to investigate the titanite in these Emeishan basalts. Our objectives were to determine the origins of the titanite and its relationship to the polymetallic Nb layer in the lowermost Xuanwei Formation. The basalts consist of approximately 70%–90% phenocrysts and 10%–30% matrix. The phenocrysts are mainly coarse-grained (>30 μm) plagioclase, clinopyroxene, and Fe-Ti oxides (ilmenite and magnetite), whereas the matrix comprises mainly fine-grained (<30 μm) titanite and glass. The titanite is hypautomorphic or xenomorphic and occurs as small, disseminated grains within the matrix. The titanite U-Pb dating of basalt sample reveals a Tera–Wasserburg lower intercept age of ca. 259.6 ± 4.3 Ma, which corresponds to the age of the eruption timing of Emeishan large igneous province (ELIP; 260.9–257.4 Ma). This implies that the formation of titanite within the matrix can be attributed to rapid cooling of residual melt subsequent to fractional crystallization of a substantial quantity of phenocrysts. The LA-ICP-MS analysis reveals that the trace element composition of titanites in the Emeishan basalts exhibits similarities to weathering-type titanite, as evidenced by elevated La N /Yb N ratios and low concentrations of Y, ΣREE, Th, and U, as well as reduced Lu/Hf and Th/U ratios. Thus we propose that these titanites crystallised during the late-stage magmatic evolution, resulting from magmatic fractional crystallization and subsequent weathering alteration. The materials required for titanite crystallization in the basalt matrix primarily sourced from the residual melt, while weathering dissolution of plagioclase and clinopyroxene in the phenocrysts may have provided additional Ca and Eu for titanite formation. As weathering progressed, the Nb-rich titanite underwent a transformation into Nb-rich anatase and gradually became enriched in the regolith. This material was subsequently transported to nearby basins and deposited in terrestrial environments, resulting in formation of the polymetallic Nb layer in the lowermost Xuanwei Formation. Our findings provide insights into the origins and evolution of titanite in the Emeishan basalts, as well as formation of the polymetallic Nb layer in the lowermost Xuanwei Formation in the eastern Yunnan–western Guizhou region, southwest China. [Display omitted] • Nb-rich titanite is widely present in the Emeishan basalts in the southwest China. • The titanite originated from fractional crystallization and weathering alteration. • The Nb-rich anatase in the Xuanwei Formation was derived from ELIP basalts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The xenotime U–Pb age of 426 ± 6.0 Ma (2σ) records a regional metamorphic event. • Two hydrothermal xenotime yielded U–Pb ages of 256.0 ± 4.1 Ma (2σ) and 254.4 ± 2.1 Ma. • Hydrothermal titanite shows an age of 255.4 ± 0.8 Ma. • Ore-forming fluids dominantly originated from the crustal sources. The Haoyaoerhudong gold deposit, located in the northwestern part of the North China craton (NCC), has produced over 120 metric tonnes (t) of gold since 2007. It has a total reserve of > 240 t at average gold grade of 0.62 g/t, making it one of the largest open pit gold mines in China. The steeply dipping, large-tonnage, low-grade, vein- or veinlet-type gold orebodies are hosted in strongly-deformed Mesoproterozoic carbonaceous schist of the Bayan Obo Group. The laminated/boudinaged veins/veinlets in the sinistral ductile–brittle shear zones are dominated by quartz, biotite, gold-bearing löllingite, pyrrhotite, (arseno)pyrite, with minor native gold, titanite and xenotime. In this paper, we present new in situ U–Pb geochronological data on magmatic zircon from the pre-ore dikes, on metamorphic and hydrothermal xenotime, and on hydrothermal titanite from the hydrothermally altered carbonaceous schist and auriferous quartz–sulfides veins/veinlets, as well as He-Ar isotopic analysis on gold-bearing (arseno)pyrite in the syn -ore stage. The metamorphic xenotime U–Pb age of 426 ± 6.0 Ma (2σ) records a regional metamorphic event, possibly related to the accretion of the Bainaimiao arc onto the NCC. Two pre-ore andesitic dikes yielded similar emplacement ages at ∼ 278 Ma constrained by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb zircon data. Hydrothermal xenotime grains from the altered carbonaceous schist and auriferous quartz–sulfides veins yielded U–Pb ages of 256.0 ± 4.1 Ma (2σ) and 254.4 ± 2.1 Ma (2σ), respectively, overlapping with that of the hydrothermal titanite at 255.4 ± 0.8 Ma (2σ) from the laminated quartz–sulfides veinlets. This indicates that the gold mineralization occurred at ca. 255 Ma. The ∼ 255 Ma gold mineralization age is much younger than the previously reported Early–Middle Permian regional magmatic activity (ca. 291 Ma to 268 Ma), and may be associated with the regional sinistral strike-slip event in the late orogenic cycle related to the collision between the Siberian craton and the NCC. The 3He/4He (R/Ra) and 40Ar/36Ar values of the gold-bearing (arseno)pyrite are 0.04 to 0.09 (average = 0.07) and 375.8 to 2023 (average = 1045), which reveal the ore-forming fluids dominantly originated from the crustal rocks, with limited involvement from the mantle. Collectively, our new geochronological data, noble gas isotopic analyses, and geological evidence support a typical orogenic gold deposit model at Haoyaoerhudong. [ABSTRACT FROM AUTHOR]

In the pegmatite body of the locality Dunje (Pelagonian metamorphic complex) the association rutile-titanite was examined using the SEM-EDS method and it has been determined that rutile appears as the first generation within the metamorphic evolution of the Pelagon, while titanite appears as the second one as a result of metamorphic-metasomatic processes in the presence of a fluid phase rich in Ca, Fe, P, Si. [ABSTRACT FROM AUTHOR]