Lead Isotope Ratios Research Articles

A Study on The Characteristics of The Raw Materials and The Manufacturing Techniques for Glassy Layers on The Wave-shaped Tiles Excavated from The Sacheonwangsa Temple Site

In this study, the material characteristics of glassy layers on the wave-shaped tiles excavated from the Sacheonwangsa Temple Site were identified, and the manufacturing techniques and their characteristics were examined. The samples were ten green glassy layers separated from tiles. These samples were 2.62 to 4.43 mm thick and were sorted light and dark green. As a result of quantitative analysis of green glassy layers, PbO was calculated from 73.0 to 78.9 wt.% (average 76.7 wt.%), SiO2 was calculated from 21.2 to 27.0 wt.% (average 23.3 wt.%). Therefore, it is presumed that high-lead glassy layers were made with high-purity silica stone and lead. In addition, as a result of comparing the correlation between lead isotope ratios and trace and rare earth elements in the glassy layers, it was confirmed that they were largely divided into two groups. It is presumed that it was manufactured by fixing the wave-shaped tiles that had completed firing to a frame, putting a molten glassy onto it, and cooling it. Based on these morphological and material characteristics, it is closer to the glass than the glaze.

Separation or integration? Further insights from a study on chemical datasets of ancient bronze drums from South and Southeast Guangxi, China

Bronze drums of Types Beiliu and Lingshan, two of the eight types of bronze drums in China, represent the highest level of bronze industry in Guangxi during the Han and Tang dynasties. Because of their distinctive ethnic features and generous size, they have received significant attention. Through the study of 12 drums of Type Beiliu and 7 drums of Type Lingshan, the provenance of ore sources, ethnic characteristics, and their correlations are further discussed. According to the analysis results, the above two types of bronze drum share some common features in alloying patterns, lead isotope ratios, and trace elements. However, they exhibit differences in decorative traditions. This research concludes that although the above two types of bronze drums belong to different local powers, extensive communication existed regarding the boundary. A complex relationship of integration, separation, and confrontation existed among them, which was typical of ancient ethnic society.

The Role of Lead Glass Plate and Correlation Analysis of Raw Materials in Mireuksa Temple Site, Iksan

We interpreted the role and meaning of nine lead glass plates excavated from the Mireuksa Temple site in Iksan and investigated their materials. Glass plates were excavated from all areas of the site, especially around Geumdangji and the eastern pagoda. The lead glass was presumed to have been partially installed in the symbolic space of the temple. Quantitative analysis of the lead glass (ICP system) determined that PbO comprised 74.2 to 79.5% wt. of the glass (average 76.6% wt.), which was higher than that reported for the glass in prior studies (approximately 70% wt.). Regarding the correlation between lead isotope ratios and trace elements in the glass, the Baekje and Silla cultures showed clear distinctions, and the origin of other materials was confirmed for each culture. Therefore, a constant composition ratio was maintained when producing lead glass and procuring raw materials through various routes. The above results can provide data for understanding the technical systems regarding ancient glassy materials and reproducing them using future manufacturing technologies.

Effects of Mantle Hybridization by Interaction with Slab Derived Melts in the Genesis of Alkaline Lavas across the Back-Arc Region of South Shetland Subduction System

AbstractLate Miocene to Late Pleistocene alkaline lavas in the northernmost part of the Antarctic Peninsula and its off-lying islands are the latest stage of magmatic activity that took place in response to lithospheric extension in the back-arc region of the South Shetland subduction system. The alkaline magmatism occurred much later than the main pulse of Cretaceous arc magmatism and generated basaltic extrusive rocks during several sub-aqueous/sub-glacial and sub-aerial eruption periods. The suite consists primarily of alkali olivine basalts with oceanic island basalt (OIB)-like trace element signatures, characterized by elevated highly to less incompatible element ratios compared to MORB. The samples have higher 87Sr/86Sr (0.70301–0.70365), and lower 143Nd/144Nd (0.51283–0.51294) and 176Hf/177Hf (0.28291–0.28298) than depleted MORB mantle. Their lead isotope ratios vary within a limited range with 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb ratios of 18.797–18.953, 15.577–15.634, and 38.414–38.701, respectively. Sr, Nd, Hf and Pb isotope systematics suggest involvement of diverse source materials in the genesis of the alkaline magmas. Evaluation of radiogenic isotope and trace element data indicates that the source of the alkaline melts had a complex petrogenetic history, reflecting the effects of mantle hybridization along the slab mantle interface through interaction of mantle wedge peridotites with volatile-bearing, siliceous melts produced by melting of subducted sediments and basaltic oceanic crust. Hf-Nd isotope and trace element projections further demonstrate that the metasomatizing melt was likely generated by eclogite partial melting at sub-arc to post-arc depths, in equilibrium with a garnet-bearing residue and involved breakdown of high field strength elements (HFSE) retaining phases. Consumption of metasomatic amphibole during partial melting of hybridized peridotite at the wet solidus appears to have had a significant effect on the final melt compositions with high HFSE, Na and H2O contents.

Cultural exchange and integration: archaeometallurgical case study on underneath-blade bronze dagger-axes from Shuangyuan Village Site in the Eastern Zhou Dynasty

As typical artifacts of the Ba-Shu culture, bronze dagger-axes have always been highly valued by academia. Underneath-blade bronze dagger-axes were utilized widely in both the Central Plains and southwest China. However, opinions differ on whether these underneath-blade bronze dagger-axes which excavated from Ba-Shu culture were produced locally. Combined with archaeological typology study, p-XRF and MC-ICP-MS were used to analyze 12 underneath-blade bronze dagger-axes unearthed from Shuangyuan Village Site, an Eastern Zhou cemetery in Chengdu city, Sichuan Province, Southwest China in order to investigate the cultural exchange and integration centered on the Shu culture. The composition results show that the majority of samples were made from copper, tin, and lead ternary alloy. The data on lead isotopes indicate that underneath-blade bronze dagger-axes have different mineral sources. The lead isotope ratio 206Pb/204Pb of 18.3 can draw the conclusion to be used as one of the bases for judging that underneath-blade bronze dagger-axes originated in the Chengdu Plain or the Central Plains which was consistent with the typology. The southern China lead materials of underneath-blade bronze dagger-axes in the Ba-Shu and Central Plains style probably came from southern Sichuan; while the rest of underneath-blade bronze dagger-axes in the Central Plains style might use lead materials in the western Hunan-western Hubei area. The Shu culture which was represented by Shuangyuan Village Site in Chengdu Plain during the Eastern Zhou Dynasty had close cultural communication with the Central Plains and Chu cultures. This study reveals that Ba-Shu had a direct exchange of minerals or metal products with the Central Plains and Chu, as well as an imitation based on the identification of the foreign culture and the belief in the local Shu cultural traditions.

Sources and trends of trace elements and polycyclic aromatic hydrocarbons in a shallow lake in the Mediterranean area from sediment archives of the Anthropocene

In this study, the anthropogenic contamination in Trasimeno lake (Central Italy) was investigated using three sediment cores spanning over the last 150 years (Anthropocene) to identify the primary sources of pollution and quantify the level of contaminant enrichment in the basin. First, based on the relative cumulative frequency and linear regression methods, we obtained a geochemical baseline for the lake using the deeper parts of the sediment cores. The geochemical baseline allowed us to determine the values of trace elements enrichment factors. On this knowledge, as a second result, we were able to reconstruct the natural sources and the anthropogenic impact on the lake with a biennial resolution. This goal has been obtained by combining different inorganic and organic chemical proxies such as trace elements, polycyclic aromatic hydrocarbons, and lead isotope ratios and exploiting both principal component and factor analysis to associate chemical proxies to human-driven contamination processes. Five different groups of elements have been identified, one of which is of natural origin and four of anthropogenic origin. In particular, it was possible to identify the times and impacts of the industrial activities during the Second World War, which dispersed heavy metals in sediments. Moreover, we found evidence of the recent human activities that have characterized the surroundings of the basin, such as Pb inputs related to the use of gasoline and the enrichment of certain elements generally used in agricultural activities (such as P, Cu, and Mn) due to the development of this sector in the last 40 years.

A Practical Procedure for Analysis of Lead Isotopes in Bivalve Shells Using Laser Ablation Multicollector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS).

Lead, like other trace elements, is incorporated in the growing bands of bivalve shells. The chemicals stored into the shells can provide valuable information about seawater conditions during the period of shell formation. In this study, we present a practical approach to determine Pb isotopic signatures in bivalve shells as a tool for evaluating lead pollution in coastal waters. To demonstrate the applicability of the method, Pb isotopic fingerprinting in bivalve shell layers were investigated using laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). Lead isotope ratios (208Pb/206Pb and 206Pb/207Pb) were measured along distinct sections of the maximum growth axis of the shells. Calibration and quantification of Pb isotopes were performed using NIST 612 as reference material. Our results demonstrated that Pb isotope ratios in the shells ranged from 1.143 to 1.201 for 206Pb/207Pb and from 2.061 to 2.161 for 208Pb/206Pb. The isotopic signatures recorded in the sample shells correspond to similar ranges of Pb signatures reported for marine sediments from the same study area. In general, this work shows that LA-MC-ICP-MS is a suitable technique for determining spatially resolved lead isotopic signatures in bivalve shells and that it can be used to estimate the origin of Pb pollution in aquatic environments.

Source apportionment based on lead isotope ratios: Could domestic dog's blood lead be used to identify the level and sources of lead pollution in children?

Domestic dogs have been proved to be used as “sentinel organisms” to monitor human lead exposure. However, whether dogs' blood can be used to identify the levels and pollution source of children's lead exposure still needs evidence. To evaluate the potential use of domestic dogs' blood lead as an indicator of lead exposure levels and pollution source of children, accompanying with potential environmental media samples, lead concentrations and isotope ratios (expressed as 207Pb/206Pb, 208Pb/206Pb) in blood were investigated and compared between children and dogs, who came from a Pb–Zn smelter area, a coal fired area and a control area without industrial activity. The results showed that there were significant correlations in blood lead levels (BLLs) between children and dogs in the study areas (p < 0.01). The lead isotope ratios (LIRs) in blood of children and dogs were disparate among the three areas, however, the LIRs of dogs were quite correlated with those of children in each area (p < 0.01). With the comparison of LIRs between potential pollution sources (slag, ore, coal, paint) and blood samples, the identified lead sources based on dogs' blood were found to be coincident with those based on children's blood. Ore smelting and coal combustion were the main sources of lead exposure for the dogs and children in the smelting area, and coal combustion was the predominant source for the children and dogs living in the coal burning area and control area. The results showed that dogs' BLLs might be used to estimate children's BLLs, and blood LIRs measurements of dogs' could be used as an alternative for identifying the sources of children's lead exposure. This study further provided relevant evidence for dogs to be sentinels exposed to human lead exposure and an alternative method for source apportionment of children's lead exposure.

Can Isotopes Be Used as Lead Tracers in Shooting-Range Soils?

Lead isotopes have been widely used to assess the sources of Pb in the soil environment since lead isotopes ratios have a specific signature that allows us to use them as environmental tracers. However, some lead sources are difficult to be identified. This article contains the lead isotope data from soils and shot pellets collected in an abandoned shooting range (NW Spain). Twelve soil and three-shot pellet samples were randomly collected and analyzed using MC-ICP-MS. The isotope ratios are shown, and analyses proved that Pb originated predominantly from the used shot pellets. Contaminated soils exhibited an isotopic composition (206Pb/207Pb, 208Pb/204Pb, 206Pb/204Pb and 208Pb/206Pb) close to some shot pellets from different manufacturers. These results offer new, valuable data for other researchers working on lead contamination research and the identification sources of Pb for adjacent areas to shooting-range facilities and for wildlife ecotoxicology. Still, the use of several ammunitions derived from different sources, such as recycled Pb, showed that it is hard to identify the lead source and these kinds of facilities.

Determination of lead isotope ratios by inductively coupled plasma mass spectrometry and comparison of lead isotope ratios among different samples

Determination of lead isotope ratios by inductively coupled plasma mass spectrometry and comparison of lead isotope ratios among different samples

Archaeometallurgical research on the bronze coins of Song Dynasty (960–1279AD) from Nanhai No. Ⅰ shipwreck, the south China sea

The Song Dynasty (960–1279 CE) was a prosperous period for China's maritime trade and also an era when coins flowed abroad. Song coins were not only used as currency in neighboring countries in East and Southeast Asia at the time, but also appear to have been used as metalwork. However, many details of both maritime history and numismatics have yet to be elucidated, and even comprehensive scholarly information on indigenous Chinese currency is incomplete. In this insufficient research situation, EDXRF, metallography, MC-ICP-MS and ICP-AES were employed to investigate the alloy composition, microstructure, lead isotope and trace element characteristics of 14 Song Dynasty coins from Nanhai No. Ⅰ shipwreck in this study. The XRF results show that all the samples are Cu-Sn-Pb ternary alloy. The metallography results show three types of as-cast microstructures. According to the lead isotope ratios, the diverse provenances of the lead material of the Nanhai No. Ⅰ coins are clearly different from the Japanese ancient coins. In addition, the trace element data suggest that the copper raw materials for the coins came from several mines. These preliminary results may provide background data to facilitate questions related to the maritime history of East and Southeast Asia.

Shiny bronze in glassy matter: an inconspicuous piece of slag from the Bronze Age mining site of Mušiston (Tajikistan) and its significance for the development of tin metallurgy in Central Asia

This paper aims at contributing to a better understanding of the beginnings of tin and bronze metallurgy in Central Asia by investigating a hitherto unique piece of a bronze slag. The object was originally discovered as a stray find only 4 km away from the large copper-tin deposit of Mušiston in Tajikistan. It contains many prills of bronze and copper as well as small charcoal particles. Radiocarbon dating of the charcoal places the slag in a period between 1900 and 1400 BCE and thus in the Late Bronze Age of the region. This date coincides with radiocarbon dates of relics from underground galleries of the Mušiston deposit. Chemical and microscopic examination demonstrated the slag to be a relic of a co-smelting process, in which a natural assemblage of tin and copper minerals was smelted simultaneously. Both the chemical and the tin and copper isotope compositions clearly link the slag to the nearby polymetallic ores from Mušiston, of which an extensive dataset is presented. The artefact’s lead isotope ratios and increased iron concentration in turn indicate intentional fluxing of the original ore charge with iron-dominated ores. These results are the first tangible evidence of a smelting process of tin ores in the entire region and therefore add a new dimension to the findings from previous mining archaeological investigations. At the same time, the results give significant information about the smelting process of secondary polymetallic ores from Mušiston and help in assessing the scientific data of Bronze Age bronze artefacts from Central Asia.

Sickles from the Sosnovaya Maza hoard of the Late Bronze Age from the Lower Volga region: Technological analyses, experiments and chronology

The Sosnovaya Maza hoard was discovered by chance in the Saratov region in the Lower Volga in 1901 without any archaeological context. Based on the sickle form and the metal composition–copper with an elevated level of iron–so called Sosnovaya Maza type of sickles was singled out. The comparative analysis of the production technology and the alloying and lead isotope composition of the Sosnovaya Maza type of sickles found in the Volga region, in the Urals and the northern Kazakhstan sites helped obtained more data on the metalworking of this period which became a wide spread activity and required search of new deposits and new sources of surplus.The tracewear study assessed that all sickles were cast in a univalve mold with a flat lid. The ICP-MS analysis determined a rather high heterogeneity of the hoard item elemental composition as well as significant variability in the level of trace elements in the metal. Research experiments through smelting of chalcopyrite raw material and native copper from the Osenneye copper pyrite deposit in Ural melt was conducted, the copper obtained in general correspond to the copper composition of the Sosnovaya Maza tools.Significant variability of the isotope ratios of lead isotopes of Sosnovaya Maza hoard items confirms our hypothesis that raw material came from several ore sources: copper pyrite deposits in the southern Urals (the Trans-Urals and the northern periphery of the Urals-Mugodzhary region); Late Permian oxidized ores of the Urals from the Kargaly (Sakmar-Samara region) mining; and the metallurgical region and deposits characterized by the very radiogenic 208Pb/204Pb, localization of which at the moment does not seem possible. The analyses of the Alekseyevskoye items imply that it might be northern Kazakhstan.The 14C date obtained is used as a chronological marker for the Sosnovaya Maza type sickles and the entire Sosnovaya Maza hoard. This enabled us to narrow down the time interval during which such sickles made from ferrite copper were used and date the hoard to 1400–1300 calBC. The study identified the role of new metalworking provinces located in the eastern part of the Eurasian world.

Identifying the Geographical Origin of Tobacco Leaf by Strontium and Lead Isotopic with Mineral Elemental Fingerprint

The primary aim of this paper was to identifying the geographical origin of tobacco leaves based on stable isotopic and mineral elemental fingerprint. We collected eighty-one tobacco leaf samples from Argentina, Brazil, Zimbabwe, the U.S., Zambia, and China. And nine mineral element contents and four strontium and lead isotope ratios of the tobacco leaves were determined by thermal ionization mass spectrometry (TIMS) and inductively coupled plasma mass spectrometry (ICP-MS). After variance and stepwise discriminant analysis, the discriminant functions of the tobacco leaf’s geographical origin were established. The results indicate that: (1) the contents of six mineral elements including Cu, Zn, Cr, Ni, Cd, and Pb, together with four strontium and lead isotope ratios containing 87Sr/86Sr, 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb, were significantly different among six countries. (2) Different countries presented some characteristic mineral elemental and isotopic fingerprint. The even contents of mineral elements from Zambian tobacco leaf were much lower than the other countries, among which four elements consisting of Zn, Cr, As, and Cd were not detected. The three average lead isotope ratios including 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb from Zimbabwe tobacco leaves were far higher than the other countries, and the range of which was unoverlapped. (3) The effective identification of the geographical origin of tobacco leaf was accomplished by Fisher stepwise discriminant analysis and the characteristic tracing elements consisted of Cu, Zn, Cr, Ni, Cd, Pb, 87Sr/86Sr, 207Pb/204Pb, and 206Pb/204Pb. Based on the established discriminant functions, the original and cross-validation accuracy towards different geographical origins of tobacco leaves were 98.8% and 95.1%, respectively. The study shows that the strontium and lead isotopic with mineral elemental fingerprints is a potential effective method to identify the geographical origin of tobacco leaves from different countries.

Bioaccessibility, source and human health risk of Pb, Cd, Cu and Zn in windowsill dusts from an area affected by long-term Pb smelting

Non-ferrous metal smelting results in heterogenous spatial distribution of potentially toxic metals (PTM) near smelters. In this work, windowsill dusts were collected from smelting (SA) and urban (UJ) sub-areas of Jiyuan (a city affected by >70 years of Pb smelting) to investigate PTM source and bioaccessibility. The <10 μm fraction of dusts were analyzed for total and bioaccessible Pb, Cd, Cu and Zn concentrations; bioaccessibility was analyzed by a three-stage assay (i.e., lung phase, gastric phase and gastrointestinal phase) using artificial lysosomal fluid (ALF, L phase) followed by simulated gastric and gastrointestinal fluids (G and GI phases). This assay mimicked the movement of particles phagocytosed by alveolar macrophages in the respiratory system, then transported up the oropharynx and subsequently swallowed and transported into the digestive system. Zinc had greater bioaccessible concentrations in L and GI phases than other metals, and the mean L phase bioaccessible PTM concentrations in SA were greater than in UJ. The mean L + GI phase bioaccessible concentrations of Pb, Cd, Cu and Zn in SA were 280, 79, 124 and 1458 mg kg−1, while those in UJ were 215, 54, 116 and 598 mg kg−1, respectively. The L phase extracted 87.7 to 98.8 % of PTM within the L + GI assay. Lead had a lower L + GI bioaccessibility than Cd, Cu and Zn (70–76 % vs. 82–92 %). Higher tolerable Cd carcinogenic risks based on bioaccessibility were found in SA sub-area than in UJ while no carcinogenic or non-carcinogenic risk was found for other metals. Lead isotopic ratios indicated that both Pb ore and smelting bottom ash contributed to dust Pb accumulation in SA, while coal burning, lead ore, Pb smelting bottom ash and diesel engine exhaust contributed to dust Pb accumulation in UJ. Overall, results indicated heterogenous distribution of PTM source and bioaccessibility in the vicinity of Pb smelters.

Metal consumption of a middle-range society in the late 3rd millennium BC Anatolia: A new socioeconomic approach.

This article discusses the socioeconomic dynamics of metal consumption patterns in the 3rd millennium BC north-central Anatolian site of Resuloğlu (Çorum, Turkey). The socio-political structure of the site confirms a nonstate, socially complex community with a range of hierarchical and heterarchical expressions. This study presents the results of archaeological, compositional (n = 307), and isotopic (n = 45) analyses of the complete metal collection of Resuloğlu uncovered through two decades of systematic excavations with a well-established chronology. The elemental compositions of metal objects obtained with pXRF combined with lead isotope analysis denote a high diversity in alloy types and sources. The compositional analysis highlights the consumption of various binary and ternary alloys for different object types. The lead isotope ratios confirm the use of both in proximity to metallic sources and access to macro-regional trade extending from the Black Sea coast towards the Taurus Mountain range. The site appears as a part of linkages whereby goods and valuables were exchanged within decentralized networks of middle-range societies. The diversity in metal consumption suggests group-driven choices and networks rather than top-down control of social elites. This allows us to confront the conventional approach to the role of metals as the primary motivator for social complexity and inequality in all parts of the 3rd millennium BC Anatolia.

Copper at ancient Kerma: A diachronic investigation of alloys and raw materials

This paper describes the first comprehensive study of metal artefacts found at ancient Kerma, Sudan. Covering a period of several millennia, it investigates the development of copper alloy recipes as well as metal provenance through the trace element and lead isotope ratio analysis of forty-eight sampled objects. These include grave goods as well as production waste related to large-scale bronze casting performed at Kerma. This study is part of a wider evaluation of copper alloy production at Kerma through targeted workshop excavation, materials analysis, and experimental archaeology. The analytical results illustrate the gradual and flexible transition from arsenical copper to tin bronze alloys over time, in a pattern similarly observed in ancient Egypt. Trace element distributions and lead isotope ratios for copper used at Kerma are comparable to those of contemporary Egyptian artefacts too. These findings indicate the exploitation of ores similar to those mined at the Sinai Peninsula, although copper ore deposits in Nubia remain poorly characterized and thus difficult to identify as source candidates. Nonetheless, it can be suggested that metal provisioning networks along the Nile Valley likely overlapped to varying degrees over time. These results provide an important contribution to the mapping of technological exchanges that took place between ancient Egypt and Nubia.

Genesis of the Taishanmiao Au Deposit in the Ningshan–Zhenan Ore Field, South Qinling Orogen, China: Evidence from Geochemical, Geochronological and S‐Pb‐H‐O Isotopical Study

AbstractThe Taishanmiao Au deposit is in the western part of the Ningshan–Zhenan ore field, in the South Qinling orogen. Based on geological and geochemical features, we propose that the Taishanmiao Au deposit is a magmatic‐hydrothermal type of deposit. All samples have high SiO2, K2O + Na2O contents and differentiation index values, low CaO, MgO, P2O5, and TiO2 contents, are enriched in high field‐strength elements, and depleted in large ion lithophile element. The stable isotope δ34S values of pyrite vary from 6.8%–7.8%, and the H‐O isotopic compositions of quartz from quartz‐pyrite veins indicate the ore‐forming fluid is a mixture of a small amount of magmatic‐hydrothermal solution and groundwater. Lead isotope ratios of pyrite and silicalite can show that the ore‐forming materials were derived from a mixed source containing mantle and crustal materials. At the same time, the LA‐ICP‐MS U‐Pb dating of monzogranite is 198.4 ± 4.2 Ma. Combined with the regional geological background, the intracontinental extension in the late collisional orogeny and large‐scale lithospheric thinning associated with mantle uplift may lead to large‐scale mineralisation in the region.

Geological and geochemical constraints on the genesis of the Xiqianluzi Pb–Zn polymetallic deposit in Beishan, Gansu Province, NW China

The Xiqianluzi Pb–Zn polymetallic deposit is located in the southeast of the southern Beishan belt, whereas the ore‐forming metal sources are still unclear. Its Pb–Zn ore bodies mainly occur in the Changcheng system Qianluzigou Group metamorphic clastic rocks, showing zonation of Cu–Zn–Pb metals from deep to surface. The ore structures are mainly banded, massive and veined, which have the characteristics of syngenetic sedimentation. Au mineralization in silty slate is obviously controlled by WNW–ESE‐trending faults, and occurs as veined or lenticular type. The Pb, Zn, Cu, and Au are mainly enriched in quartz or siliceous veins. The biotite granodiorites are enriched in Si, Na, Rb, Ba and K, with A/CNK values less than 1.1, and depleted in Nb, P, Ti. They belong to calc‐alkalic series and weak peraluminous I‐type granite, formed in a post‐collision extensional environment and characterized by crust–mantle mixed source. The sulphide minerals in the Pb–Zn ores have δ34S values in the range of 17.7‰–21.0‰ with average of 19.2‰, reflecting seawater sulphate origin of sulphur. The sulphur of Pb–Zn ores was likely transformed from S6+ to S2− by thermochemical sulphate reduction. The Pb isotopic compositions of sulphide minerals in the Pb–Zn ores have 206Pb/204Pb ratios of 16.837–17.001, 207Pb/204Pb ratios of 15.437–15.557, and 208Pb/204Pb ratios of 36.377–36.889. In contrast, sulphide minerals in Au ores have δ34S values (5.4‰–7.6‰, with average of 6.5‰) lower than those of sulphide minerals in the Pb–Zn ores. The δ34S values of sulphide minerals in the Au ores are consistent with those of sulphide minerals in the Late Permian–Middle Triassic magmatic hydrothermal gold deposits in the southern Beishan belt, which imply a magmatic source for sulphur. Sulphide minerals in the Au ores have higher lead isotopic ratios, including 206Pb/204Pb of 18.249–18.325, 207Pb/204Pb of 15.583–15.598, and 208Pb/204Pb of 38.023–38.366, compared to those in the Pb–Zn ores. Geological and isotopic features indicate that the Xiqianluzi Pb–Zn polymetallic deposit comprises two mineralization types; namely, its Pb–Zn ores can be considered as Mesoproterozoic sedimentary exhalative type, while its Au ores are magmatic origin. These show that Au mineralization was closely related to the magmatic hydrothermal activities, and thus Au ores can be classified as Late Permian–Early Triassic magmatic hydrothermal Au mineralization.

Isotopic profiling of natural uranium mined from northern Nigeria for nuclear forensic application

Four mined samples of natural uranium from northern Nigeria were studied through inductively coupled plasma mass spectrometry, at the Environmental Analytical Chemistry Laboratory, University of the Witwatersrand, Johannesburg. The samples were characterised for lead, thorium and uranium isotopic concentrations, isotopic ratios and age. The objective was to obtain nuclear forensic fingerprints as baseline data to add to the Nigerian National Nuclear Forensic Library. Results showed significant variation in the isotopic concentrations of lead, thorium and uranium across the mines. Isotopic ratios of 238U/235U, 235U/238U and 234U/238U across the sample of 137.881±0.007, 7.253×10-03±2.05×10-04 and 5.540×10-05±4.08×10-07 were found to be consistent with the natural values. The age of natural uranium is comparable to the age of earth. Uranium, lead, and thorium isotopic concentrations and ratios, as well as the age of the samples characterised, provide an isotopic profile that can be used for nuclear forensic application. Significance: Given the abundant deposits of natural uranium in Africa and the consequent potential for nuclear insecurity, determining the isotopic profiles and signatures of natural uranium is important for application in nuclear forensics. Isotopic concentrations of 232Th, 238U, 235U and 234U from the respective sampling sites differed significantly, thereby providing characteristic isotopic profiles.