Arrays of near-concordant U-Pb zircon ages are interpreted to develop during (i) long-lived geological events involving protracted periods of zircon growth or (ii) mobilization and escape of radiogenic Pb during a secondary event. However, distinguishing between either interpretation remains challenging. In this contribution we investigate the complex geochronology of a meta-gabbro from the Mawson Charnockite plutonic complex in East Antarctica. Previously published work on this sample produced a near concordant Pb-loss age array spanning 400 million years despite showing a narrow range of 176Hf/177Hfi values consistent with a single population of zircons. Zircons from the meta-gabbro are characterised by relative homogenous internal textures with no evidence of crystal plastic deformation nor significant radiation damage that would otherwise be consistent with diffusion related Pb-loss. In this study, in-situ laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb isotope and trace element spot analyses in selected, representative grains from the meta-gabbro were combined with high-resolution backscatter electron imaging to link U-Pb isotopic and trace element variability to microstructures. Microstructures indicative of former coupled-dissolution precipitation replacement reactions such as abundant micro-scale porosity transgressing the interior of grains and sharp compositional reaction interfaces are common and are interpreted to be directly linked to enhanced trace element and U-Pb isotope mobility. Within each studied grain, several U-Pb analyses within a defined textural domain produced arrays of near-concordant dates spanning hundreds of millions of years between 500 Ma and 1000 Ma, where trace element concentrations are progressively depleted with increasingly younger dates. Our observations demonstrate that Pb-loss arrays, where only the oldest and youngest ages may be geologically significant, can result from variable trace element mobility and redistribution during melt-mediated coupled dissolution-precipitation replacement reactions within zircon.

This study addresses a significant gap in the geochemical literature by systematically investigating garnet compositions within and around base metal deposits -- a topic that remains relatively understudied, despite the mineral's known significance in various geological contexts. Garnet, traditionally associated with diamond exploration and recognized for its potential as an indicator mineral for deposits like skarns,emerges in our research as a key geochemical tracer in the context of base metal exploration.Focusing on the Eastern Succession of the Mount Isa Inlier in Australia, a globally significant mineral province, we characterized the major and trace element compositions of garnets associated with diverse base metal systems. Our new dataset, containing more than 2500 datapoints, was complemented by literature data compiled from a range of mineral systems including skarns, IOCGs, subaqueous volcanic-related (VMS, Broken Hill, sedimentary-exhalative), porphyry-epithermal and granite-related pegmatite systems. Comparative analyses with background metamorphic/igneous garnets reveal distinct trends in Mn-Fe and Ca-Mg space in ore-associated garnets, along with unique trace element patterns (e.g., Eu anomalies) and chalcophile element variations (e.g., Zn, Cd, Ga) in diverse ore systems.To clarify the importance of these anomalous compositions, we refined our dataset by considering specific garnet associations and their related geological context. Garnets in the database were categorized depending on their occurrence within the ore bodies, the alteration haloes, or the background lithologies. Additionally, we carried out a multivariate statistical analysis through a principal component analysis (PCA) and subsequent cluster analysis, to identify hidden spatial patterns. Our results shed light on the geochemical variations in garnet composition across various ore systems and provide new insights into the sources of these variations.This research not only contributes valuable geochemical data for base metal exploration but also establishes the efficacy of multivariate statistical analyses in deciphering complex garnet data structures. The implications of our findings extend beyond the Eastern Succession of the Mount Isa Inlier, fostering a broader understanding of the geochemical dynamics associated with base metal deposits globally.

Transparent, mostly small, pale yellow to brown zircon megacrysts occur with gem corundum in alluvial deposits associated with alkali basalts in the Inverell-Glen Innes District of the New England gem fields, New South Wales, Australia. In a previous study, U-Pb ages of zircon from the Kings Plains, Mary Anne Gully and Swan Brook localities were determined using LA-ICP-MS data. An analytical traverse across one crystal revealed chemical homogeneity, indicating stable crystallisation conditions. The 206Pb/238U ages of the zircons from the three localities fell into two groups: an older set ranging from 216 to 174 million years (Ma) and a younger group of 45-37.7 Ma, indicating two main formational events in the Late Triassic-Early Jurassic and Eocene time periods. New data obtained from zircon inclusions in two gem-quality blue sapphires gave 206Pb/238U concordant average ages of 37 +/- 1.7 Ma and 35.1 +/- 1.6 Ma for samples from Kings Plains and Mary Anne Gully, respectively. The ages of both inclusions fall within the K-Ar age range of basalt from the Maybole volcanic suite (38-33 Ma) and correlate well with the age range of the younger zircon megacrysts. Combined with the gemmological features and chemical fingerprints of the sapphires, the age data offer valuable insights into their geological origin by providing a genetic link between gem corundum crystallisation in the deep crust or mantle and transport to the Earth's surface in alkali basaltic magma.

The Mount Garnet Zinc deposit in NE Queensland, Australia, is located in the region of voluminous magmatism associated with the formation of Palaeozoic continental arcs of Gondwana. Ore-forming events of this deposit are related to the intrusion of the Kennedy Igneous Association (KIA) – a large suite of igneous rocks spanning Late Carboniferous to Early Permian in age – into the Silurian limestone (Chillagoe Formation) in the Hodgkinson Province (Mossman Orogen). Petrographic observations and in situ major and trace element analysis reveal the sequence of garnet growth and fluid-rock interaction during skarn formation. Three types of garnets are identified, Grt I (including IA and IB) and Grt II. Grt IB is related to Zn-Pb mineralization. All garnets have elevated Sn and W and the highest levels of W and Sn are observed in Grt II. Garnet U-Pb ages of Grt IB provide the first direct geochronological result of hydrothermal minerals in the Mount Garnet region. New data argues that the base metal mineralization may take place during early Permian period and be sourced from the Claret Creek Supersuite. Sn-W mineralization may be associated with the O’Briens Creek Supersuite.

Understanding the main events of platinum -group element (PGE) ore formation is impossible without analysis of the sources and behavior of major ore -forming components, namely, platinum, osmium, sulfur, and copper, which are important indicators of magmatic and hydrothermal processes. In contrast to the Re-Os isotope system, the radiogenic Pt-Os isotope system, as well as stable isotopes of Cu and S in PGE deposits, are still relatively understudied. Our comprehensive research is aimed at filling this gap. The paper presents data for the Guli massif of ultramafic and alkaline rocks and carbonatites in Polar Siberia and on the zonal Nizhny Tagil and Svetly Bor clinopyroxenite-dunite massifs in the Middle Urals, which include: (1) the contents of the highly siderophile elements (HSE) in whole rocks and platinum -group minerals (PGM), (2) the Re-Os and Pt-Os isotope systematics of chromitite, Os-Ir alloys, and Ru-Os sulfides, (3) the sulfur isotope composition in Ru-Os and Ir-Rh sulfides in primary and secondary PGM assemblages, and (4) the copper isotope composition in Pt-Fe minerals from chromitites and placers. The research was performed using scanning electron microscopy, electron probe microanalysis, and high -precision isotope-geochemical analysis. The high -precision Re-Os and Pt-Os isotope data show that the HSE contents in chromitites and PGM of the Guli massif were controlled by the composition of the mantle source that evolved with nearchondritic time -integrated Re/Os and Pt/Os ratios, which are also typical of the sources of most komatiites and abyssal peridotites. The delta 65Cu values of the studied samples of ferroan platinum and isoferroplatinum are identical within the analytical uncertainty and are close to 0 parts per thousand, which is typical of high -temperature Cu -containing minerals. The sulfur isotope compositions of the Ir-Rh sulfides of the kashinite-bowieite series and of the Ru-Os sulfides of the laurite-erlichmanite series in the primary PGM assemblages indicate that the source of sulfur has a chondritic isotope composition, which is in agreement with the osmium isotope composition of the Ru-Os sulfides and Os-Ir alloys. The heavy sulfur isotope composition (delta 34S = 5.6 +/- 1.5 parts per thousand) of As -containing erlichmanite is consistent with its secondary origin. The new data on the isotope compositions of osmium, copper, and sulfur can be used as new important parameters that characterize the sources of PGE mineralization.

Понимание главных событий платинометалльного рудообразования невозможно без анализа источников и поведения главных рудообразующих компонентов, а именно платины, осмия, серы и меди, являющихся важными индикаторами магматических и гидротермальных процессов. В отличие от Re-Os изотопной системы, изотопные системы Pt-Os, меди и серы платинометалльных месторождений до сих пор остаются слабоизученными. Выполненное нами комплексное исследование направлено на частичное восполнение данного пробела. В статье представлен обширный набор данных, включая: 1) содержания сильносидерофильных элементов (ССЭ) в породах и минералах платиновой группы (МПГ), 2) Re-Os и Pt-Os изотопные вариации в хромитите, Os-Ir сплавах и Ru-Os сульфидах, 3) изотопный состав серы Ru-Os и Ir-Rh сульфидов в составе первичных и вторичных минеральных ассоциаций МПГ, 4) изотопный состав меди Pt-Fe минералов из хромититов и россыпных месторождений Гулинского массива ультраосновных и щелочных пород с карбонатитами в Полярной Сибири и зональных Нижнетагильского и Светлоборского клинопироксенит-дунитовых массивов на Среднем Урале. При проведении исследований были использованы сканирующая электронная микроскопия, рентгеноспектральный микроанализ и прецизионные изотопно-геохимические методы анализа. Высокоточные Re-Os и Pt-Os изотопные данные свидетельствуют, что содержания ССЭ в хромититах и МПГ Гулинского массива в значительной степени контролировались составом мантийного источника, который эволюционировал с околохондритовыми интегрированными по времени Re/Os и Pt/Os отношениями, характерными также для источников большинства коматиитов и абиссальных перидотитов. Значения δ65Cu для изученных образцов железистой платины и изоферроплатины в пределах погрешности неотличимы друг от друга и характеризуются изотопными составами меди, близкими к 0 ‰, что типично для высокотемпературных Cu-содержащих минералов. Особенности изотопного состава серы Ir-Rh сульфидов ряда кашинит—боуит и Ru-Os сульфидов ряда лаурит—эрликманит в составе первичных ассоциаций МПГ свидетельствуют в пользу ее источника с хондритовым изотопным составом, что находится в согласии с данными по изотопному составу осмия для Ru-Os сульфидов и Os-Ir сплавов. Изотопно-тяжелый состав серы (δ34S = 5.6 ± 1.5 ‰) As-содержащего эрликманита согласуется с его вторичным происхождением. Выявленные особенности изотопного состава осмия, платины, меди и серы могут быть использованы в качестве новых дополнительных параметров, характеризующих условия образования платиноидной минерализации. Understanding the main events of platinum-group element (PGE) ore formation is impossible without analysis of the sources and behavior of major ore-forming components, namely, platinum, osmium, sulfur, and copper, which are important indicators of magmatic and hydrothermal processes. In contrast to the Re–Os isotope system, the radiogenic Pt–Os isotope system, as well as stable isotopes of Cu and S in PGE deposits, are still relatively understudied. Our comprehensive research is aimed at filling this gap. The paper presents data for the Guli massif of ultramafic and alkaline rocks and carbonatites in Polar Siberia and on the zonal Nizhny Tagil and Svetly Bor clinopyroxenite–dunite massifs in the Middle Urals, which include: (1) the contents of the highly siderophile elements (HSE) in whole rocks and platinum-group minerals (PGM), (2) the Re–Os and Pt–Os isotope systematics of chromitite, Os–Ir alloys, and Ru–Os sulfides, (3) the sulfur isotope composition in Ru–Os and Ir–Rh sulfides in primary and secondary PGM assemblages, and (4) the copper isotope composition in Pt–Fe minerals from chromitites and placers. The research was performed using scanning electron microscopy, electron probe microanalysis, and high-precision isotope-geochemical analysis. The high-precision Re–Os and Pt–Os isotope data show that the HSE contents in chromitites and PGM of the Guli massif were controlled by the composition of the mantle source that evolved with near-chondritic time-integrated Re/Os and Pt/Os ratios, which are also typical of the sources of most komatiites and abyssal peridotites. The δ65Cu values of the studied samples of ferroan platinum and isoferroplatinum are identical within the analytical uncertainty and are close to 0‰, which is typical of high-temperature Cu-containing minerals. The sulfur isotope compositions of the Ir–Rh sulfides of the kashinite–bowieite series and of the Ru–Os sulfides of the laurite–erlichmanite series in the primary PGM assemblages indicate that the source of sulfur has a chondritic isotope composition, which is in agreement with the osmium isotope composition of the Ru–Os sulfides and Os–Ir alloys. The heavy sulfur isotope composition (δ34S = 5.6 ± 1.5‰) of As-containing erlichmanite is consistent with its secondary origin. The new data on the isotope compositions of osmium, copper, and sulfur can be used as new important parameters that characterize the sources of PGE mineralization.

В статье раскрыто общее понятие и значение административных регламентов, в том числе проанализировано значение административных регламентов в деятельности прокуратуры.

Most of Earth’s volcanism occurs at tectonic plate boundaries associated with subduction or rifting processes. The mantle plume hypothesis is an important supplement to plate tectonics for explaining some high-volume intraplate volcanic fields. However, many intraplate magmatic provinces occur as low-volume, monogenetic basaltic-suite fields that are neither associated with plate-boundary processes nor attributable to mantle plumes, and the origin of such magmatism has long been debated. Identification of their source characteristics and possible mechanisms that trigger mantle melting will provide essential insights into Earth’s mantle heterogeneity and also develop our knowledge of tectonic plate movement through time. Here, we report new geochronology, mineral chemistry (especially olivine), and whole-rock chemical and Sr-Nd-Pb-Hf isotopic compositions on Cenozoic intracontinental alkaline basalts from the northwestern Tarim craton (central Asia), aiming to better assess the origin of Earth’s low-volume effusive intraplate volcanic fields. The basalts (ca. 42 Ma) have olivine (e.g., mean Ni abundances of ∼2250 ppm, mean Mn/Zn ratios of 13.7) and whole-rock chemistry consistent with their derivation from a mixed peridotite-pyroxenite source. Moderately depleted Sr-Nd-Pb-Hf isotopes (87Sr/86Sr = 0.7039−0.7053; εNd = +4.0 to +5.5; 206Pb/204Pb = 18.247−18.535; εHf = +8.1 to +8.7) require a young (ca. 500 Ma) oceanic crust recycled into the source, possibly related to subduction events during the assembly of Pangea. Estimated thermal-chemical conditions indicate that the original melting occurred in a relatively dry (H2O = 1.4 ± 0.9 wt%) and reduced (logfO2 ΔFMQ = −0.97 ± 0.21, where FMQ is fayalite-magnetite-quartz) asthenosphere under a mantle potential temperature of ∼1420 °C and a pressure of ∼3.7 GPa (corresponding to a depth of ∼120 km). Combining these data with regional tectonic history and geophysical data (high-resolution P-wave tomography), we propose that the long-lasting India-Eurasia collision triggered asthenospheric upwelling, focusing melts along translithospheric zones of weakness; this model provides a robust explanation for the observed Cenozoic intracontinental volcanism in central Asia. The integrated geochemical and geophysical evidence reveals that plate subduction−induced mantle upwelling represents a likely mechanism for the generation of many regions of plume-absent intraplate magmatism within continents.

ABSTRACT Subduction recycling of sediments plays a key role in the geochemical evolution of Earth. The presence of recycled terrigenous sediments in upwelling plumes has been cited to explain the EM2 signature in ocean island volcanics, characterized by particularly high 87Sr/86Sr (>0.706). However, the origin of such isotopic anomalies in continental regions and the role of subducted sediments in the subcontinental lithospheric mantle (SCLM) remain unclear. The Himalaya–Tibet orogen is one of the world’s best places for deciphering continental subduction and the fate of subducted crustal materials in the mantle. Here we present a systematic study of the geochronology, mineral chemistry (especially clinopyroxene), whole-rock chemistry and Sr–Nd–Pb–Hf–O isotopic compositions of Cenozoic potassic–ultrapotassic lavas from the western Kunlun area of northwestern Tibet. New secondary ion mass spectrometry (SIMS) zircon U–Pb dating, coupled with published age results, constrain the timing of volcanism from ~8.3 Ma to the present. These lavas show geochemical characteristics that closely resemble the EM2 mantle end-member represented by the Samoan hotspot. Both whole rocks and individual magmatic clinopyroxenes display arc-like trace-element patterns and remarkably enriched Sr–Nd–Pb–Hf isotope compositions (87Sr/86Sr ≥ 0.7080; εNd ≤ −4.8; 206Pb/204Pb ≥ 18.704; εHf ≤ −2.6). Together with high zircon δ18O values (6.3–10.4‰), the data point to a mantle source enriched by recycled sedimentary materials. Geochemical modeling and geophysical evidence further indicate that the sediments were directly derived from the subducted Indian continental lithosphere during India–Eurasia collision. Partial melting models assuming a hybridized mantle source that contains ~5% Indian continental crust suggest that the primary melts of the potassic–ultrapotassic lavas could be formed by melting of a phlogopite-bearing garnet lherzolite at low melting degrees (1–5%). The magma geochemistry is consistent with the model of mélange melting, implying that the subducted sediments may detach from the downgoing Indian slab and rise up diapirically into the overlying mantle lithosphere. Unlike traditional models of subducted sediments entering the deep mantle, the western Kunlun EM2-like lavas reveal that subducted sediments can be rapidly recycled into the SCLM during continental subduction (probably <50 Myr). We suggest that the SCLM could be an important reservoir for subducted sediments. The findings are important to our understanding of mantle circulation rates and chemical heterogeneities.

Plate tectonic models for the amalgamation of the dominantly Paleo-Mesoarchean Western Dharwar Craton (WDC) and Neoarchean Eastern Dharwar Craton (EDC) remain inconclusive on the polarity of Neoarchean subduction. Here we present insitu U-Pb age and Hf-O isotopic compositions of xenocrystic zircons in ca. 1.4-1.1 Ga kimberlites and lamproites emplaced within the ca. 2.8-2.5 Ga EDC as deep probes of the crustal architecture across the WDC-EDC boundary. The different zircon populations yield wide range of ages extending back to ca. 3.6 Ga, including distinctly 'kimberlitic zircons' with a mean 206Pb/238U age of 1112 +/- 42 Ma, consistent with previous age estimates for kimberlite magmatism. The presence of zircons with ages > 3.33 Ga is surprising as this age group of zircons is atypical of magmatic rocks in the EDC, but wide-spread in the WDC. Also, the highest concentration of zircons with ages > 3.0 Ga is found in the kimberlites closest to the notional boundary shear zone between the WDC and EDC. The Hf isotope systematics of a majority of magmatic zircons with ages between 2.75 and 2.50 Ga require melting of older (3.6-3.3 Ga) source rocks. O-isotope data for these Neoarchean zircons show a wide scatter, lie both above (818O to 13.5 %o) and well below mantle values (818O to < 2 %o). 818O values outside the mantle range are closely associated with low epsilon Hf. The data are interpreted as evidence for trans-portation of older upper crustal rocks to lower crust and mantle depths consistent with tectonic models invoking collisional under thrusting of WDC beneath EDC.

Nine Paleozoic sedimentary formations from western Tasmania and two from the Lachlan Orogen-one in northeast Tasmania and one in Waratah Bay in Victoria-contain detrital zircons that fall into major U-Pb age clusters at 2.0-1.4, 1.25-0.95 and 0.62-0.49 Ga. The zircon Th/U ratios and rare earth element (REE) patterns suggest a magmatic origin for detrital zircons in all these rock sequences. The REE geochemical signatures on bivariate discrimination diagrams indicate that most of the zircons originated in continental orogenic settings. The oldest group of zircons have a southwest Laurentian signature previously recognised from Proterozoic metasedimentary rocks in Tasmania. The 1.25-0.5 Ga zircons from all the samples have very similar epsilon Hf-i values. They are not statistically different from those of typical Lachlan Orogen sandstones and resemble those in Rodinia and early Gondwana orogenic belts. The epsilon Hf-i values of the Cambrian zircons within the Pioneer Sandstone are similar to the Mount Read Volcanics but cannot be distinguished on epsilon Hf-i values from other sources in East Gondwana. The detrital zircon provenance of the Bear Gully Chert Bed at the base of the Digger Island Marlstone at Waratah Bay includes the west Tasmanian Proterozoic, the East Gondwana margin and the Macquarie Arc. This mixed provenance provides evidence for the late Cambrian docking of VanDieland with East Gondwana.

&lt;p&gt;We present multi-disciplinary datasets reporting petrography, major and trace element geochemistry, and U-Pb geochronology for the Mount Garnet Cu-Pb-Zn skarn deposit, NE Queensland, Australia. The deposit is hosted in limestones of the upper Silurian Chillagoe Formation, within the Hodgkinson Province, Mossman Orogen. Its mineralisation has been interpreted to be related to the intrusion of the Kennedy Igneous Association (~250-345 Ma), however, the exact timing is still not determined.&lt;/p&gt;&lt;p&gt;Petrographic observations and &lt;em&gt;in suit&lt;/em&gt; major and trace element analysis using EPMA and LA-ICP-MS on skarn garnets reveal two generations of garnet formation. Garnets from Gt-I generation are anhedral and massive, dark brown to red in colour. They are mostly Al-rich grossular (Adr&lt;sub&gt;6-22&lt;/sub&gt;Grs&lt;sub&gt;61-88&lt;/sub&gt;) and show no zoning patterns. Garnets from Gt-II generation are euhedral with a yellow-green colour and porous textures. They are Fe-rich andradite (Adr&lt;sub&gt;10-99&lt;/sub&gt;Grs&lt;sub&gt;16-77&lt;/sub&gt;) and display oscillatory zoning. Gt-I grossulars have an enrichment in LREEs and depletion in HREEs with negative Eu anomalies, while Gt-II andradites have the opposite trend and prominent positive Eu anomalies. Both W and Sn are present in Fe-rich garnet (&gt;10 ppm). &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;238&lt;/sup&gt;U ages of two types of garnets are ranging from ~220 Ma to 380 Ma, consistent with the zircon U-Pb age range (~295-335 Ma) from ore-related intrusions.&lt;/p&gt;&lt;p&gt;Our data allows the exploration of relationships between magmatism, tectonic activities, and the chronological sequence of mineralisation-related processes. A general order of events would include the very early silicification occurring within the host rock and accompanied by potential faulting, followed by the prograde and retrograde metamorphic process, which is represented by garnet, clinopyroxene, considerable vesuvianite, and calcite, along with minor wollastonite at the skarn front. Compositional variations (e.g., Mn concentration) of zoned Gt-II constrain the P-T-X condition of fluids and high Eu/Eu* and Ce/Ce* ratios within both garnets indicate a relatively oxidised skarn system. Negative correlations between Ca and REEs suggest that the incorporation and fractionation of REEs in garnet are collectively controlled by crystal chemistry and the presence of hydrothermal fluids. Further results of garnet geochronology would provide additional constraints on the nature of magmatic sources in the region.&lt;/p&gt;

The Mesozoic was punctuated by relatively brief periods of anomalous warmth associated with pulses of volcanism, intensified weathering, expansive marine anoxia, and increased organic carbon burial. These are known as oceanic anoxic events (OAEs). Several OAEs have also been linked to potentially synchronous episodes of increased carbon burial in lacustrine settings, attributed to increased weathering-derived nutrient fluxes. Here we present the Early Aptian oil shale sequences of western Liaoning Province, north China, combining sediment petrology, zircon U-Pb geochronology, carbon isotope chemostratigraphy, as well inorganic and organic geochemical palaeoenvironmental proxies to assess possible causal links to OAE1a. New zircon 206Pb/238U ages (121.06 +/- 0.63 Ma, 119.72 +/- 0.40 Ma, and 119.9 +/- 0.65 Ma) for three tuffs and delta 13Corg chemostratigraphic correlation show that the western Liaoning Province oil shale interval formed shortly after widespread marine black shale deposition characteristic of OAE1a had ceased. Elevated concentrations of alginite (dinoflagellate-derived organic matter) in oil shale samples which contain micron-thick tuff layers suggest that arc volcanism in north China was the major factor driving increased lacustrine carbon burial, via volcanic ash fertilisation. This is supported by high values of Babio, C27/C29 alpha alpha alpha-20R steranes, C28/C29 alpha alpha alpha-20R steranes, 4-methylsterane index, dinosterane index, and tetramethylsterane index in these layers, which imply that the input of volcanic ash contributed to a flourishing of brackish/saline-water adapted dinoflagellates, leading to the formation of organic-rich tuff laminae. This is a novel mechanism that is distinct to the processes known to have contributed to enhanced marine organic matter burial on a global scale during OAE1a. This research not only contributes to the study of lacustrine source rocks in north China, but also provides insights into the influence of intermediate-acidic volcanic eruptions on organic carbon burial more generally.

В статье анализируются понятия «международной организации» и «международной правосубъектности», как они взаимосвязаны друг с другом. Международные организации являются особыми субъектами в международном праве, имеющими свои права и обязанности, в связи с этим их правоспособность отличается от иных субъектов международного права.

The Tasmanian Devonian granites were emplaced during the Tabberabberan Orogeny when the East and West Tasmania Terranes were sutured. The primary aim of this study is to determine zircon O and Lu-Hf isotope constraints on, and relationships between, the magmas forming these granites. A second aim is to determine if these zircon isotopic compositions can be used to inform granite-related ore endowment. Several granites (n = 11 in East Tasmania Terrane, n = 1 West Tasmania Terrane) were previously dated by U-Pb geochronology using SHRIMP, and the zircon pits from the dating analyses were targeted firstly in O and later in Lu-Hf isotope analyses. The magmatic zircon delta O-18(VSMOW) results ranged from mantle-like values (< 5.7 parts per thousand) to values like supracrustal rocks (similar to 12 parts per thousand). The granites with the lowest most mantle-like zircon delta O-18 are all I-types, and these include the relatively mafic Lisle to the very felsic and highly fractionated Mt Stronach and Tombstone Creek plutons. The Tombstone Creek zircon epsilon Hf-i results are significantly lower than those of Lisle and Mt Stronach, indicating distinct melt sources from which the zircons crystallized. The magmatic zircon delta O-18 and epsilon Hf-i results revealed two distinct paths of infracrustal to upper crustal rock epsilon Hf-i- delta O-18 melt evolution: one "high epsilon Hf" path linking the results from the Lisle, Mt Stronach, Hazards, Henbury, Lottah, Gipps Creek and Royal George granites, and the other "low epsilon Hf" path linking those from Tombstone Creek, Meredith, Poimena, Bicheno and Ansons Bay granites. The paths are statistically different and modeled results are consistent with mixing of Mathinna Supergroup rocks with different isotopically defined infracrustal/mantle-like components. The high epsilon Hf group of granites are strongly associated with granite-related Au, Sn, and Sn-W ore deposits. (C) 2022 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Ophiolitic rocks of the Lachlan Orogen are important because they can provide key information used to refine existing tectonic models for the orogen. This study focuses on the serpentinite belts within the greater Tumut region of the Lachlan Orogen in southeastern Australia. U-Pb, Lu-Hf, O isotopic and trace-element data collected on zircons from a plagiogranite of the Wambidgee Serpentinite Belt are consistent with their crystallisation from mantle-derived melts. Their juvenile Hf-isotope compositions, with epsilon Hf ranging from +7 to +14, and delta O-18 values ranging from 4.35 to 5.07 parts per thousand, are close to typical mantle values and clearly within the range defined for zircons from plagiogranites of ophiolitic complexes worldwide. When combined with zircon data available for the Coolac Serpentinite and recent petrogenetic modelling for the Coolac Serpentinite Belt, a new U-Pb age of 486 +/- 3 Ma of the Wambidgee zircons constrains the age of formation of oceanic lithosphere in the greater Tumut region to Cambro-Ordovician.

In-situ analysis of minerals, such as zircon hafnium (Hf) and oxygen (O) isotopes, has been pivotal in investigating magmatic evolution and related ore systems. In order to better constrain the petrogenesis of Cu-porphyries and related ore-forming processes in southern Tibet, we used a combined application of both zircon by Hf-O isotopes and apatite by developing geochemical indicators involving Sr-O isotopes and volatile (chlorine and sulfur) concentrations. Apatite has several advantages over zircon: it carries ore-related volatiles, is present in less-evolved magmas and is sensitive to magmatic processes. Data on major- and trace elements and Sr-O isotopes in gem-like apatite can supplement information from zircon Hf-O isotopes. We have applied these techniques to granitoids from the Jurassic arc in southern Tibet to illustrate their use in tracing volatile evolution and related genesis of porphyry systems. We demonstrate that (1) robust apatite Sr-O isotopes combined with zircon Hf-O isotopes can record recycled oceanic components in the sources of Gangdese Jurassic porphyries; (2) volatile-enriched magmas metasomatised hydrous mantle wedge to form the Jurassic mineralised rocks; (3) the ore-forming magma with higher contents of water, Cl and S, favoured the transfer of metals and volatiles to the upper crust and to form the Jurassic porphyry Cu-Au deposits.

In order to provide further insights into the origin of Ru-Os-Ir alloys, this study presents new highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundance and 187Re-187Os and 190Pt-186Os isotope data for detrital grains of native Ru-Os-Ir alloys in placer deposits of the Kunar and Unga Rivers, which display a close spatial association with the Kunar dunite–harzburgite complex in the northern part of the Taimyr Peninsula in the Polar Siberia. The study utilized electron microprobe analysis, negative thermal ionization mass-spectrometry (N-TIMS) and laser ablation multiple-collector inductively coupled plasma mass-spectrometry (LA MC-ICP-MS). The primary nature of the Ru-Os-Ir alloys is supported by the occurrence of euhedral inclusions of high-Mg olivine (Fo92–93) that fall within the compositional range of mantle olivine. The LA MC-ICP-MS data show similar average initial 187Os/188Os and γ187Os(740 Ma) values for PGM assemblages from the Kunar and Unga deposits of 0.1218 ± 0.0010, −0.18 ± 0.85, and 0.1222 ± 0.0025, +0.10 ± 2.1, respectively. These values are identical, within their respective uncertainties, to the initial 187Os/188Os value of the Ru-Os-Ir alloy grain measured by N-TIMS (0.1218463 ± 0.0000015, γ187Os(740 Ma) = −0.1500 ± 0.0012). The combined 187Re-187Os isotopic data for all studied grains (γ187Os(740 Ma) = −0.02 ± 1.6) indicate evolution of the Kunar and Unga mantle sources with a long-term chondritic 187Re/188Os ratio of 0.401 ± 0.030. In contrast to the 187Os/188Os data, the initial 186Os/188Os value of 0.1198409 ± 0.0000012 (µ186Os(740 Ma) = +34 ± 10) obtained for the same Ru-Os-Ir alloy grain by N-TIMS is suprachondritic and implies evolution of the Kunar and Unga mantle source(s) with a long-term suprachondritic 190Pt/188Os ratio of 0.00247 ± 0.00021. This value is ~40% higher than the average chondritic 190Pt/188Os ratio of 0.00180 and indicates long-term enrichment of the Kunar source in Pt over Os. Establishing the source of this enrichment requires further investigation.