Laser Ablation Inductively Coupled Plasma Mass Spectrometry Research Articles

Mineralogy and geochemistry of magnetite in the Zhdanov Ni-Cu-(PGE) deposit in the Pechenga ore field, Russia: Implications for the formation of magmatic sulfide ores

The mineralogy and chemical composition of magnetite and chromite series (simplified as magnetite) can provide valuable insights into the formation processes of magmatic Ni-Cu-(PGE) sulfide deposits. Previous studies mainly focus on magnetite in disseminated ores and massive ores, but very little is known about the magnetite in net-textured ores. In this study, magnetite in net-textured ores (type 1 magnetite) and massive ores (type 2 magnetite) from the Zhdanov Ni-Cu-(PGE) deposit in the Pechenga ore field, were recognized and analyzed using scanning electron microscope (SEM), electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Both the type 1 and type 2 magnetite grains show zoned textures with Cr concentration decreasing from the core to the rim. Type 1 magnetite has higher Al and Mg concentrations than type 2 magnetite. These observations indicate that type 1 and type 2 magnetite crystallized from and record the solidification process of silicate melt and sulfide liquid, respectively. Type 1 magnetite within sulfides of net-textured ores has identical chemical composition to that within silicates, which suggests that the chemical composition of magnetite is not significantly affected by sub-solidus re-equilibrium with sulfide minerals. It also suggests that the type 1 magnetite within sulfides was incorporated into sulfide liquid later during the downward percolation of sulfide liquid through the magnetite-bearing olivine crystal mush. On the other hand, type 2 magnetite has comparable concentrations of W, Sc, Ga, Cr, Mo, and Mn to the type 1 magnetite. Such compositional similarity can be explained by the crystallization of type 2 magnetite from the sulfide liquid pool that have been mingled with the downward percolated sulfide liquid. Accordingly, the downward percolation of sulfide liquid plays an important role in the formation of net-textured ores and massive ores in the Zhdanov deposit.

Assessment of Viability of Coal Mines in Tanzania for Extraction of Rare Earth Elements

This study aimed at determining the concentrations of rare earth elements (REEs) in coal and coal fly ash (CFA) from three coal mines in Tanzania: Kiwira, Ngaka and Rukwa. The goal was to assess if these resources could be commercially viable for extracting REEs. Coal and CFA samples were analysed using X-ray fluorescence (XRF) spectrometry and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The total concentrations of REEs in the coal samples ranged from 89.48 parts per million (ppm) to 196.30 ppm, while in CFA samples, ranged from 362.55 ppm to 475.77 ppm. Computed percentage of critical REEs (REYdef, rel%) and outlook coefficient (Coutl) values ranged from 27.41% to 50.74% and 0.62 to 2.00, respectively. Based on the evaluation criteria proposed for assessing coal and coal ash as sources of REEs, the results suggest that the studied coal and CFA samples have the potential to be used as sources of REEs for economic development. These findings have important implications for the Tanzanian government and other relevant authorities, as they provide valuable insights into the feasibility of investing in the coal and coal ash as promising sources of REEs. This is particularly significant considering the high global demands for REEs.

Age and Tectonic Setting of Layered Lead–Zinc Ore Bodies in the Xiaohongshilazi Deposit: Constraints from Geochronology and Geochemistry of the Volcanic Rocks in Central Jilin Province, NE China

The newly discovered Xiaohongshilazi deposit located in Panshi City, central Jilin Province, NE China, is a medium-scale Pb–Zn–(Ag) deposit. The Pb–Zn–(Ag) orebodies are divided into layered and vein-type orebodies, which have different ore geneses. The layered Pb–Zn orebodies are mainly hosted within and spatially controlled by the volcanic rocks. To constrain the age and tectonic setting of the layered Pb–Zn mineralization, we completed laser-ablation–ICP–MS zircon U–Pb dating and whole-rock major and trace element analyses of the ore-bearing volcanic rocks. The dacite samples were confirmed as belonging to the Daheshen Formation and were the main ore-bearing volcanic rocks for the layered orebodies. They yielded concordia U–Pb ages of 278.1 ± 1.8 Ma and 278.3 ± 1.8 Ma, respectively, indicating that the volcanic rocks from the Daheshen Formation and related layered Pb–Zn mineralization were formed in the early Permian. The andesite and rhyolite located above the layered orebodies yielded concordia U–Pb ages of 225.0 ± 1.1 Ma, 225.3 ± 1.5 Ma, and 224.7 ± 1.2 Ma, respectively; these substances are considered to be of the Sihetun Formation and were first reported in the area. The dacite samples associated with layered Pb–Zn mineralization were high in SiO2 (62.54–65.02 wt.%), enriched in LREEs and LILEs (e.g., Rb, Ba, and K), and showed depletion in HFSEs (e.g., P and Ti). It showed slightly negative Eu anomalies (δEu = 0.60–0.65) and negative Nb anomalies, with Th/Nb (1.12–1.21) and La/Nb (2.8–4.7) ratios, presenting subduction-related arc magma affinity formed in an active continental margin setting. In agreement with previous studies on zircon Hf isotopes (εHf (t) = +0.23~ +10.60) of the volcanic rocks from the Daheshen Formation, we infer that they were derived from the partial melting of the depleted lower crust. In conclusion, mineralization characteristics, geochronological data, geochemical features, and regional tectonic evolution suggest that two Pb–Zn–(Ag) mineralization stages from the Xiaohongshilazi deposit occurred: the layered VMS-type Pb–Zn mineralization associated with the marine volcanic rocks from the early Permian Daheshen Formation, which was induced by the subduction of the Paleo-Asian oceanic plate beneath the northern margin of the North China Craton, and the vein-type Pb–Zn–(Ag) mineralization caused by the subduction of the Paleo-Pacific Plate in the early Jurassic. Considering this, along with the mineralization characteristics of the same-type polymetallic deposits in this region, we propose that the early Permian marine volcanic rocks have great prospecting potential for the VMS-type Pb–Zn polymetallic deposits.

Petrogenesis of oxide-apatite mineralization associated with proterozoic anorthosite massifs at Lac Mirepoix, Quebec, Canada: A multi-injection model for Fe-Ti-P mineralization in the Central Grenville Province

The Lac Mirepoix Fe-Ti-P mineralization presents several mineralized lenses that outcrop near the border of the 1080 (±2) Ma Vanel and the 1016 (±2) Ma Mattawa Anorthosite massifs, in the Central Grenville Province, Quebec, Canada. The mineralization is (hemo)-ilmenite-dominated, accompanied by magnetite and apatite. It is subdivided in three different zones due to the appearance of different cumulate phases: zone I comprises mainly massive oxide (>70 % hemo-ilmenite ± magnetite) layers hosted in anorthosite. Towards the center of the mineralization (zone II), massive oxide layers are less common whereas apatite-bearing cumulates appear, forming massive nelsonite (50–70 % magnetite ± ilmenite and 25–30 % apatite) and oxide apatite norite (OAN, 15–25 % hemo-ilmenite ± magnetite and 8–20 % apatite). Finally, zone III is marked by the alternance of OAN layers (10–25 m), richer in magnetite, in addition to (hemo)-ilmenite and apatite, and an absence of massive oxide and nelsonite. In-situ trace element analysis of plagioclase, apatite and oxides by laser ablation ICP-MS, reveals cryptic variations related to magma differentiation and multiple injections of ferrodiorite parental magmas of similar composition. In-situ U-Pb dating of zircon from the OAN mineralization itself indicates two different crystallization ages between zone III (1048 ± 8 Ma) and zone I (964 ± 9 Ma), favouring a model of multiple injections of similar Fe-Ti-P-rich melts of similar composition over a period of 80 Mys rather than in-situ crystallization of a single intrusion, which is supported by trace-element geochemistry. The Lac Mirepoix mineralization records the following fractional crystallization sequence of a high-Ti-P magma, residual after the anorthosite formation: first, massive oxides of hemo-ilmenite crystallized (high Ti/Fe) by oxide settling, with primitive compositions, similar to the world-class Lac Tio deposit. The oxide-apatite mineralization (nelsonite and OAN) crystallized from the residual liquid (lower Ti/Fe, evolved compositions) in which magnetite and apatite were more abundant, similar to nearby mineralization in the area (e.g. Lac à l’Orignal Fe-Ti-P deposit). The observed decrease in Ti content of the evolving melt is supported by the liquid line of descent of several ferrodiorite dykes within the host-rocks and mineralization. Finally, we propose a model of multiple injections of residual Fe-Ti-P-rich liquids drained from or filter-pressed within diapirs of plagioclase-rich mushes that were emplaced over 80 Mys apart along the same crustal detachment zone.

The ca. 349 Ma metamorphic enrichment of the Tianhu metamorphosed sedimentary Fe deposit in the eastern Tianshan: Evidence from apatite trace elements, oxygen isotopes, and U-Pb chronology

Apatite is a common accessory mineral in iron oxide-apatite (IOA), magmatic Fe-Ti oxide, and metamorphosed sedimentary Fe deposits. Apatite chronology and oxygen isotopes in the IOA deposits have been extensively studied, however, such information in the metamorphosed sedimentary Fe deposits remains poorly understood. Here, we report detailed trace elements, oxygen isotopes, and U-Pb chronology of apatite from the Tianhu metamorphosed sedimentary Fe deposit in the eastern Tianshan, NW China. To our knowledge, this is the first report on the in situ oxygen isotopes of apatite from the metamorphosed sedimentary Fe deposits. Cathodoluminescence imaging of the apatite grains from the Tianhu massive Fe ores show a homogeneous texture, suggesting that they were formed by a single event rather than multiple superimposed events. These apatite grains contain abundant fluid inclusions, and show relatively high δ18O values of 7.9 ‰-14.0 ‰ and low Th and U contents, which are consistent with their metamorphic hydrothermal origin. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) dating of the studied apatite grains yielded a U-Pb age of 348.5 ± 18.5 Ma, indicating that the metamorphic enrichment of the Tianhu metamorphosed sedimentary Fe deposit occurred considerably later than the Ordovician ore-hosting rocks. Combined with previous studies, we suggest that the metamorphic massive ores of the Tianhu metamorphosed sedimentary Fe deposit formed in an orogenic setting. Our study highlights that a combination of trace elements, oxygen isotopes, and U-Pb chronology of apatite can be used as powerful tools to constrain the genesis of metamorphosed sedimentary Fe deposits.

Gemology, Spectroscopy, and Mineralogy Study of Aquamarines of Three Different Origins

New aquamarine deposits have been found around the world in recent years, and how to compare and distinguish aquamarines of different origin has become a significant problem. Aquamarines from Koktokay, Minas Gerais, and Namaqualand were collected for standard gemology tests, spectroscopy, and chemical analysis in this paper. The spectroscopy experiment included infrared spectroscopy and Raman spectroscopy. Chemical composition analysis comprises electron microprobe and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). The results show that infrared absorption peaks related to [Fe2(OH)4] and NaH are found in Koktokay and Minas Gerais aquamarines, respectively. Compared with other two origins, Namaqualand aquamarine have strongest type II water Raman peak related to alkali metal content. Compared with aquamarines from other sources, aquamarines from Xinjiang and Minas Gerais are characterized by relatively high aluminum and low alkali contents in chemical composition, while Namaqualand aquamarine have a high scandium content.

Meso–Cenozoic Exhumation in the South Qinling Shan (Central China) Recorded by Detrital Apatite Fission-Track Dating of Modern River Sediments

The Qinling Shan is located between the North China Craton and the South China Block. Not only is investigating the exhumation process of the Qinling Shan beneficial for comprehending the tectonic collision history of mainland China but also for enhancing our understanding of the development of the Yellow and Yangtze Rivers. Previous studies have predominantly focused on bedrock analysis in the Qinling Shan. However, modern fluvial detrital samples offer a more extensive range of thermal history information. Therefore, we gathered modern fluvial debris samples from the Hanjiang River, which is the largest river in the South Qinling Shan. Subsequently, we conducted apatite fission-track analysis using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method. A total of 214 valid track ages were obtained, with an age distribution ranging from 9.5 to 334.0 Ma. The Density Plotter software was employed to decompose the data and generate four prominent age peaks: 185, 103, 69, 35, and 12 Ma. The exhumation events of the Early Jurassic (185 Ma) and Cretaceous (103–69 Ma) in the Southern Qinling Shan were strongly influenced by the collision between the South China Block and the North China Craton, as well as the subduction of the West Pacific Plate, respectively. The far-field effect of the collision between the Indian Plate and the southern Asian continent influenced the exhumation of the South Qinling Shan during the Late Eocene (35 Ma) and Middle Miocene (12 Ma), respectively. In conjunction with the reported findings, we comprehensively analyzed the geological implications of the Mesozoic and Cenozoic exhumations of the Qinling Shan. The Qinling Shan emerged as a watershed between the Ordos and Sichuan Basins in the early Mesozoic and Cenozoic, respectively. However, the exhumation and expansion of the Tibetan Plateau has forced the Yangtze River to flow eastward, resulting in its encounter with the South Qinling Shan in the late Cenozoic. The exhumation of the Qinling Shan has resulted in fault depression in the southern Ordos Basin. This geological process has also contributed to the widespread arid climatic conditions in the basin. During the Miocene, the Yellow River experienced limited connectivity due to a combination of structural and climatic factors. As a result, the Qinling Shan served as an obstacle, dividing the connected southern Yangtze River from the northern segment of the Yellow River during the late Cenozoic era.

RKV01 Rutile – A New Potential Archaean Reference Material for Microbeam U‐Pb Dating

Rutile stands as a classical mineral within U‐Pb geochronology, offering insights into both magmatic and metamorphic events, and contributing to the understanding of provenance of detrital sedimentary rocks. Addressing the paucity of high‐quality Archaean rutile reference materials suitable for microbeam U‐Pb dating, we present a natural rutile (RKV01) sourced from the Kaap Valley pluton, South Africa, positing it as a potential Archaean reference material. Major element determination was executed via electron probe microanalysis, while trace element determination was conducted using laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). The determination of U‐Pb ages involved the application of isotope dilution‐thermal ionisation mass spectrometry (ID‐TIMS), secondary ion mass spectrometry (SIMS) and LA‐ICP‐MS. The ID‐TIMS mean 207Pb/206Pb age is 3225.61 ± 0.64 Ma (2s, MSWD = 0.83), interpreted as the best estimate for the crystallisation age. The relatively high U mass fraction (~ 83 μg g‐1), extremely low Th mass fraction (~ 0.003 μg g‐1), negligible common Pb and isotopically homogeneous compositions collectively facilitated precise 207Pb/206Pb age determination via microbeam methods. Both LA‐ICP‐MS and SIMS 207Pb/206Pb ages are characterised by reproducibility and were consistent with the ID‐TIMS age within 2s analytical uncertainty. The results underscore the potential of RKV01 rutile as an Archaean reference material for microbeam U‐Pb dating.

Rutile U-Pb dating reveals the Oligocene age of the Dashuigou Te-Bi deposit and a contemporaneity with regional alkaline magmatism in Sanjiang region

The Dashuigou deposit, located in the transitional zone between the Yangtze craton to the east and the Songpan-Ganze orogen to the west, is the world’s only known deposit where tellurium and bismuth are exploited as primary products. The Te-Bi orebodies mainly occur as the dolomite-tetradymite and Te-bearing pyrrhotite veins in Triassic low-grade metamorphic rocks. The ore minerals mainly consist of tetradymite, tsumoite, tellurobismuthite, pyrrhotite, and chalcopyrite. While mineralogy and geochemistry of the ores in the Dashuigou deposit have been well documented in the past decades, the age of the Te-Bi mineralization in the Dashuigou district is not well defined due to lack of both suitable dating mineral and chronometer, and thereby impedes further understanding on its ore genesis.Hydrothermal rutile coeval with tetradymite has been identified in this study from a high-grade dolomite-tetradymite vein in the Dashuigou deposit. This rutile is closely associated with tetradymite, tsumoite, Te-bearing pyrrhotite, and contains many tiny tetradymite inclusions. Here, we present the first in situ trace element compositions and U-Pb age of these rutile crystals using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The rutile is enriched in V, Nb, Ta, Sn, and Cr, but has low contents of As, Sb, and W, indicating a magmatic origin. U-Pb dating on rutile demonstrates a well-constrained age of 32.4 ± 3 Ma, which is interpreted as the timing of Te-Bi mineralization for the Dashuigou deposit. This new age provides the first evidence suggesting that the Dashuigou deposit is contemporary with regional Eocene-Oligocene alkaline magmatism and related metallogenic event in Sanjiang region. Compared with the Beiya Te-Bi-bearing porphyry Cu-Au and Yao’an Au deposits in the alkaline magmatic belt, we propose that the Dashuigou Te-Bi deposit was likely product of a concealed alkaline magmatic-hydrothermal system. This study also demonstrates the rutile U-Pb geochronology being a powerful tool for dating unusual ore systems.

In the quest for historical Lisbon through 17th century Millefiori glass

Being Lisbon one of the world’s most important trading port and a place where historical documents attest the presence of at least four glass furnaces working between the 16th and 17th centuries, the authors decided to investigate one of the most luxurious coeval glass decorative techniques (millefiori) found in Lisbon to try to understand the trade route and raw-materials provenance of these artefacts.For this work, two Lisbon archaeological contexts were selected: Largo do Chafariz de Dentro (LCD) and Santana Convent (LCS) due to their significant amount of interesting millefiori fragments (eight fragments) and the presence of production waste (one in LCD and three in LCS). The analysis, comparison and discussion of glass production waste (PW) and archaeological glass artefacts will be carried out for the first time.For this work, macroscopic and microscopic observations were combined with the chemical characterization of colourless and coloured glass to make the morphological characterization and to determine which raw materials were employed in its production. The chemical characterization was made by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to obtain the major, minor and trace elements composition, including rare earth elements (REE).The chemical composition of the selected samples revealed that all the millefiori glasses are of soda-lime-silica type (part of them made with Levantine ashes and the other part with barilla) while the glass type of PW is was not attributed.Regarding the Lisbon millefiori glass fragments, there is a notable relation between the concentration of major components associated with the silica source, namely SiO2, Al2O3 and TiO2. Moreover, upon analysing the geochemical patterns exhibited by the production waste found in LCS context and comparing it with the pick-up glass fragments, a consistent trend emerges, implying that both were made by using either the identical silica source or, at the very least, a closely related silica source. For this reason, the possibility of a Portuguese local production may be proposed, especially when some decorative patterns are clearly from Portuguese inspiration (e.g. caravel and cross of Christ), while the authors admit that more data analysis is still required to prove this hypothesis.

Immunolabelling perturbs the endogenous and antibody-conjugated elemental concentrations during immuno-mass spectrometry imaging

Immuno-mass spectrometry imaging uses lanthanide-conjugated antibodies to spatially quantify biomolecules via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The multi-element capabilities allow for highly multiplexed analyses that may include both conjugated antibodies and endogenous metals to reveal relationships between disease and chemical composition. Sample handling is known to perturb the composition of the endogenous elements, but there has been little investigation into the effects of immunolabelling and coverslipping. Here, we used cryofixed muscle sections to examine the impact of immunolabelling steps on the concentrations of a Gd-conjugated anti-dystrophin primary antibody, and the endogenous metals Cu and Zn. Primary antibody incubation resulted in a decrease in Zn, and an increase in Cu. Zn was removed from the cytoplasm where it was hypothesised to be more labile, whereas concentrated locations of Zn remained in the cell membrane in all samples that underwent the immunostaining process. Cu increased in concentration and was found mostly in the cell membrane. The concentration of the Gd-conjugated antibody when compared to the standard air-dried sample was not significantly different when coverslipped using an organic mounting medium, whereas use of an aqueous mounting medium significantly reduced the concentration of Gd. These results build on the knowledge of how certain sample handling techniques change elemental concentrations and distributions in tissue sections. Immunolabelling steps impact the concentration of endogenous elements, and separate histological sections are required for the quantitative analysis of endogenous elements and biomolecules. Additionally, coverslipping tissue sections for complementary immunohistochemical/immunofluorescent imaging may compromise the integrity of the elemental label, and organic mounting media are recommended over aqueous mounting media.Graphical

Spectroscopy Characteristics and Color-Influencing Factors of Green Iron-Bearing Elbaite

The color-influencing factors and spectroscopy of 22 green elbaite samples were investigated using X-Rite SP62 spectrophotometry, ultraviolet–visible (UV–Vis) spectroscopy, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and infrared spectroscopy. The chromogenic components iron and manganese were found in the green elbaites; however, the bivariate correlation analysis indicated that the Mn content had no impact on the color, whereas the Fe content significantly affected both the lightness and the hue of green elbaites. The primary factors influencing the color of tourmaline were the absorption band at 720 nm caused by the Fe2+ d-d transitions and the 300 to 400 nm wide absorption edge extending to the visible range due to the O2−-Fe3+ charge transfer. Infrared spectroscopy indicated that the color of tourmalines was also influenced by their structure. As the degree of Y and Z octahedral distortion in the tourmaline lattice increased, the lightness of the tourmaline decreased and its color deepened. The hydroxyl region of the infrared spectra of green elbaite showed three distinct peak positions representing two types of hydroxyl vibrations: O1H at the W position and O3H at the V position. The O1H vibrations are attributed to YLiYAlYAl and XNa or X position vacancy, while the O3H vibrations are assigned to ZAlZAlYAl and ZAlZAlYLi. The presence of three peaks in the hydroxyl vibrational region of the IR spectra indicated that these samples were iron-bearing elbaites.

Geochronology of reworked ash and its implications for accommodation space variations in distal foreland basins, McMurray Formation, Alberta, Canada

A bentonite bed consisting of reworked volcanic ash from the Barremian to Aptian lower McMurray Formation is dated using chemical abrasion thermal ionization mass spectrometry (CA-TIMS) on zircon. The bentonite bed is from a cored interval in the McKay Paleovalley in the northern Athabasca Oil Sands Region of Alberta, Canada. Deposition of the lower McMurray Formation took place in the distal portion of the Western Canada Sedimentary Basin early in the Cretaceous-to-Paleocene phase of widespread contractional deformation in the Canadian Cordillera. A 30 g sample of volcanic ash yielded >10,000 very small (<50 µm) zircon grains with the vast majority (~99.7%) being highly abraded and clearly detrital. Twenty-six sharply faceted grains were sufficiently large to be mounted for laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis, which yielded seven Lower Cretaceous dates. These Lower Cretaceous grains were further analyzed using CA-TIMS. The five youngest CA-TIMS dates agree with a weighted mean of 121.51 ± 0.11 Ma which is conservatively interpreted as a maximum depositional age (MDA). The good agreement between the five zircon dates indicates the MDA is probably the depositional age. This study demonstrates that with careful analysis of zircon populations, high-confidence MDAs can be derived even from reworked ash beds that are dominated overwhelmingly by detrital zircon. The date from this study overlaps a previously published MDA of 121.39 ± 0.27 Ma for the top of the lower McMurray Formation in Firebag Tributary in the northeastern Athabasca Oil Sands Area. The overlapping dates establish a widespread chronostratigraphic surface within the northern Athabasca Oil Sands Area. Both ages are from ash beds preserved in coal seams, suggesting that the coal-bearing interval is a regional marker bed and that the ash beds may form an intraformational datum. Further, the occurrence of the ash beds in the McMurray Formation in close proximity to regional flooding surfaces suggests that tectonic activity in the emerging Canadian Cordillera influenced accommodation space variations in the distal portions of the adjacent foreland basin.

In situ U–Pb age determination of apatite from carbonatite and kimberlite in the Batain Basin, eastern Oman

Northeastern Oman is characterized by carbonatite and kimberlite complexes, which are the ideal samples for studying the relationship between carbonatite and kimberlite. However, the ages of the Oman kimberlite and carbonatite complexes are still unknown, which restricts the understanding of the relationship between carbonatite and kimberlite in Oman. In this study, we use in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to analyze the apatite from Oman carbonatite, kimberlite, and spessartite. The U–Pb apatite ages are 141.6 ± 6.0 Ma, 137.4 ± 5.2 Ma, and 141.2 ± 6.2 Ma for carbonatite, spessartite (a kind of calc-alkaline lamprophyre), and kimberlite, respectively. These results suggest that the carbonatite and kimberlite were emplaced contemporaneously, followed by calc-alkaline carbonatite (spessartite) emplaced in the Early Cretaceous. The occurrence of carbonatite, kimberlite, and spessartite magmatism of Oman was contemporaneous with the time of the Gondwana breakup during the opening of the Indian Ocean. It is seen that 140 Ma–130 Ma is one of the strongest global kimberlite abundance peaks of the 250 Ma–50 Ma kimberlite bloom, which corresponds with the period of the Pangea supercontinent breakup. The Oman kimberlites and carbonatites are related to a distal effect of the breakup of the Gondwana portion of the Pangea supercontinent, which provided a cool, volatile-fluxed decompression-related circumstance for the formation.

BITS: A Bayesian Isotope Turnover and Sampling model for strontium isotopes in proboscideans and its potential utility in movement ecology

Abstract Strontium isotope ratios (87Sr/86Sr) of incrementally grown tissues have been widely used to study movement ecology and migration of animals. However, the time scale of 87Sr/86Sr incorporation from the environment into tissue and how it may influence data interpretation are still poorly understood. Using the relocation of a zoo elephant (Loxodonta africana) named Misha, we characterise and model the 87Sr/86Sr turnover process using high‐resolution measurements of its tusk dentine. We seek to develop a framework that can improve quantitative interpretation of 87Sr/86Sr data in tissues. The 87Sr/86Sr transition associated with the relocation is measured using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) on a prepared tusk slab. We develop a turnover model (BITS), with a rapidly exchanging central pool and a slowly exchanging peripheral pool, in a Bayesian statistical framework. The measured dentine data are first used to calibrate model parameters. The parameters are then used to estimate possible 87Sr/86Sr input time series from two datasets via model inversion: a fidelity test using Misha's dentine data and a case study using published dentine measurements from an Alaskan Woolly Mammoth (Mammuthus primigenius). The LA‐ICP‐MS data are consistent with a two‐compartment turnover process with equivalent half‐lives of 41 days for the central pool and 170 days for the peripheral pool. The model inversion shows good fidelity when estimating the intake 87Sr/86Sr time series associated with Misha's relocation. In the case study, the model suggests an abrupt pattern of change in, and a much wider range of, intake 87Sr/86Sr values than expressed in the woolly mammoth dentine data themselves. Our framework bridges the gap between environmental 87Sr/86Sr variation and data measured in tusk dentine or other incrementally grown tissues. It could be coupled with movement models and additional isotope tracers to study seasonal residency or the spatial and temporal patterns of movement/migration. The generic turnover processes can be adapted to other isotope systems, additional incremental tissues, or other organisms, thus expanding our modelling toolkit to investigate niche partitioning, life history traits and behavioural patterns in conservation biology, archaeology and paleoecology.

Ore genesis of the Mengya'a distal Pb–Zn deposit in the Lhasa terrane, Tibet, China: Constraints from in situ garnet U–Pb dating and C–H–O–Sr isotopes

A large amount of distal skarn Pb–Zn deposits without any causative intrusions exposed have been discovered along the eastern Nyainqêntanglha metallogenic belt (NMB) in the Gangdese region, Tibet, China. As a typical distal skarn Pb–Zn deposit in the east of NMB, the Mengya'a deposit is adjacent to the Longmala Pb–Zn ± Cu ± Fe deposit. However, the linkage between these two deposits is not unclear due to the chaotic dating results. In situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS) U–Pb dating of reddish‐brown and yellow‐green garnet from Mengya'a yielded lower intersect ages of 53.6 ± 3.1 and 52.4 ± 4.4 Ma, respectively, indicating that Pb–Zn mineralization took place during the main collision stage of the India–Asia plates. The δDSMOW values of garnet, quartz and calcite vary from −148.4‰ to −140.4‰, −123.5‰ to −115.3‰ and −127.9‰ to −121.3‰, with the δ18OH2O values ranging from 5.8‰ to 6.6‰, 0.4‰ to 3.7‰ and 1.0‰ to 1.7‰, respectively. The δ13CV‐PDB and δ18OSMOW values of calcite range from −8.2‰ to −4.7‰ and 9.8‰ to 18.6‰, respectively. These C–H–O isotopic compositions of hydrothermal minerals indicate that the ore‐forming fluids were initially derived from the magmatic water with progressive input of meteoric water from the prograde stage to the retrograde stage. The 87Sr/86Sr(53 Ma) ratios of sphalerite (0.72321–0.73474) are consistent with those of Ando gneiss in the Lhasa‐Golmud area, indicating that the basement gneiss makes a great contribution for the source of ore‐forming materials. The newly obtained garnet U–Pb ages at Mengya'a are consistent with those of mineralization and causative intrusion in the Longmala Pb–Zn ± Fe ± Cu deposit, suggesting that the Mengya'a and Longmala deposits constitute an integrated distal skarn‐type system. This proposed hypothesis suggests that the Fe–Cu ± Pb ± Zn mineralization within the contact zone should focus on the locations beneath the identified Pb–Zn orebodies at Longmala and Pb‐21 orebody at Mengya'a.

Capturing Equatorial Pacific Variability With Multivariate Sr‐U Coral Thermometry

AbstractSr‐U, a coral‐based paleothermometer, corrects for the effects of Rayleigh Fractionation on Sr/Ca by regressing multiple, paired U/Ca and Sr/Ca values. Prior applications of Sr‐U captured mean annual sea surface temperatures (SSTs), inter‐annual variability, and long‐term trends. However, because many Sr/Ca‐U/Ca pairs are needed for a single Sr‐U value as originally formulated, the temporal resolution of the proxy is typically limited to 1 year. Here, we address this limitation by applying laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS) to three Porites colonies from Jarvis and Nikumaroro Islands in the central equatorial Pacific (CEP), generating ∼25 Sr/Ca‐U/Ca pairs per month of skeletal growth. Both Sr/Ca and U/Ca vary significantly over small (sub‐mm) length scales and support the calculation of Sr‐U values using the original regression method. Over the represented temperature range of 24–31°C, the Sr/Ca‐U/Ca‐SST relationships are nonlinear, a finding consistent with predictions of the Rayleigh model. To reflect this non‐linearity, we developed a calibration using multivariate nonlinear regression. The multivariate, three‐coral calibration was applied to 20 years of monthly resolved Sr/Ca and U/Ca of a coral interval not included in the calibration, yielding RMSE = 0.73°C and r2 = 0.85 (p < 0.05; df = 256). The multivariate calibration performed significantly better than Sr/Ca alone (r2 = 0.28). Applying the new calibration to a subfossil Porites from Kiritimati Atoll, CEP (2200 Before Present) yields equivalent phase and amplitude of interannual variability, but water temperatures ∼1.6°C cooler than they are in this region today.

Natural ilmenite reference material for trace elemental in situ microanalysis

Ilmenite is a commonly occurring mineral in both igneous and metamorphic rocks and its major and trace elements have various applications in geology, including as a geothermometer, oxygen barometer, and geochemical tracer. In this study, a 500 g ilmenite megacryst sample (LY) was developed as a reference material for in situ element microanalysis. Twenty-two ilmenite fragments, with grain sizes ranging from 1 to 8 mm, were subjected to major and trace element analysis using electron microprobe analysis (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in four different laboratories. The results indicate that the ilmenite sample is homogeneous with respect to TiO2, FeO, Mg, Sc, V, Cr and Mn, whereas Co and Nb are minor inhomogeneous. Consequently, this sample can be used as a reliable reference material for in situ microanalysis.

Interannual variability in otolith biogeochemical signatures of Japanese Spanish mackerel in the Yellow Sea

Fishes often use multiple habitats to complete their life cycles, leading to their unique otolith biogeochemical signatures. Interannual variability in otolith biogeochemical signatures is expected as fish respond to annual environmental variations in their distribution areas. In this study, we focus on Japanese Spanish mackerel Scomberomorus niphonius, an abundant commercial species in the Yellow Sea. As highly migratory fish that undergo their entire migratory cycle in a year, S. niphonius is susceptible to environmental variations. Consequently, they are believed to exhibit discernibly distinct migration patterns and varying timings of ontogenetic events across different years. Otolith biogeochemical signatures of 1-year-old spawning adults S. niphonius caught in the Yellow Sea from 2016 to 2018 were measured from core to edge using laser ablation inductively coupled plasma mass spectrometry (LAICP-MS). We hypothesized that the year-specific chemical signature could be found in 2016 as a strong El Niño Southern Oscillation event happened. From 2016 to 2018, converse ontogenetic changing patterns was observed for Sr/Ca and Ba/Ca, with Sr/Ca being positively correlated with sea surface salinity while Ba/Ca being negatively. As expected, the year-specific effect was identified for 2016 cohort but it was only significant on Ba/Ca. During this year, a stronger variation of elemental concentration and an earlier downward shift of Ba/Ca were found. These results provide evidence that otolith biogeochemical signatures have useful applications as natural tags, helping understand the interannual variability in migration of marine fish species.

Revealing the Secrets behind the Color and Sea-Wave Patterns of Larimar

In the last century, a blue–green colored gemstone known as Larimar with a special sea-wave pattern was discovered in the Dominican Republic. Larimar is composed of the mineral pectolite, which has a chemical composition of NaCa2Si3O8(OH) and is usually white in color. Cu2+ has always been considered to be the primary genesis of the blue color shown in Larimar, because native copper often grows together with Larimar. To clarify whether copper is the main reason for the origin of blue–green pectolite, we utilized laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) techniques to analyze trace elements in the pectolite samples and compared the relationship between elements and colors. The results show that vanadium and iron are the main origins of the sky-blue and green color of Larimar. We also discovered that it is not only the chemical elements that affect the color shades of the mineral, but the orientation of the radial fiber crystals also plays a critical role. The sea-wave pattern and the changes in the color saturation of radial pectolite are due to the transmittance of visible light through different viewed angles under changing crystal orientations. Our results reveal the chemical and physical factors behind the color and sea-wave pattern of Larimar. In addition, to our knowledge, this is the first time that the formation age of Larimar has been proven to be approximately equal to or younger than 40 ka, using the U-Th dating of calcite growth together with pectolite.