Sulfur Isotope Analysis Research Articles

Eelgrass meadow response to heat stress. II. Impacts of ocean warming and marine heatwaves measured by novel metrics

In June 2015, a marine heatwave triggered a severe eelgrass Zostera marina die-off event at the Virginia Coast Reserve (USA), followed by a slow and spatially heterogeneous recovery. We investigated the effects of heat stress on seagrass loss and recovery. Using hourly summer water temperature measurements from 2016-2020, we developed a novel approach to quantifying the stress of ocean warming on seagrass meadows. We defined 2 metrics: cumulative heat stress (as heating degree-hours, HDHs) and heat stress relief (as cooling degree-hours, CDHs), relative to a 28.6°C eelgrass ecosystem thermal tolerance threshold previously determined at this site from aquatic eddy covariance measurements. These metrics were compared to spatiotemporal patterns of summertime eelgrass shoot density and length. We found that the healthiest parts of the meadow benefited from greater heat stress relief (2-3×) due to tidal cooling (inputs of cooler ocean water through ocean inlets) during warm periods, resulting in ~65% higher shoot densities compared to the center of the meadow, which experienced higher heat stress (2×) and less relief. We also calculated the amount of heat stress preceding the eelgrass die-off in summer 2015, and found that this event was triggered by a cumulative heat stress of ~100-200°C-hours during the peak growing season. Sulfur isotope analyses of eelgrass leaves and sediment also suggested that sulfide toxicity likely contributed to eelgrass decline. Overall, our metrics incorporate physiological heat tolerances with the duration and intensity of heat stress and relief, and thus lay the groundwork for forecasting seagrass meadow vulnerability and resilience to future warming oceans.

Barite-bearing “septarian concretions” (upper Cretaceous – Paleocene) from the Biban area (north Algeria)

The "septarian barite concretions" have garnered significant interest worldwide. This study presents the first detailed investigation of these sedimentary structures in Algeria, with a primary focus on elucidating their genesis through petrography, SEM-EDS, major and trace elements (including REEs), and sulfur isotope analysis. The sampled concretions occur in Upper Cretaceous-Paleocene marl layers from the Biban area, primarily in two main sectors (Koudiat Djebassa and Sidi Ziane), situated within the Southern Tellian Atlas in Northern Algeria (Maghrebides). While these barite concretions exhibit diverse morphologies, our analysis focuses specifically on oblate ellipsoidal concretions. The flattened shape of these concretions may stem from compressed echinoid tests or small, oblate septarian cracked concretions representing the flattened cores. Notably, these concretions feature an outer cortex of radial fibrous barite crystals, measuring centimeters in thickness. Petrographic examination coupled with SEM-EDS analysis suggests that concretion growth occurred from porewaters in unconsolidated, soft sediments at shallow burial depths beneath the sediment-water interface, manifesting in three growth episodes: (i) an initial stage characterized by primarily thin lamellar barite crystals intertwining to form rosette-like structures in concretion cores, (ii) a later stage marked by radial-fibrous barite crystal growth in concretion margins, and (iii) the filling of septarian cracks by barite. The presence of terrigenous sediment, particularly abundant in rosette-like barite crystals, indicates growth within highly porous sediment. Conversely, the radial fibrous outer cortex is related to an effective displacive growth mode. The δ34S values of the barite concretions (ranging from 16 ‰ to 24.4 ‰), consistent with seawater values, which document that seawater was the primary sulfur source. Furthermore, REE geochemistry further supports the seawater origin of diagenetic fluids rather than a hydrothermal one. Concretions are suggested to have formed in organic-rich, fine-grained sediments at shallow depth below the sea floor, in sedimentation halts, and as a result of microbial degradation of organic matter. Barium was supplied to porewaters within the methanogenic zone, precipitating as barite when, migrating upwards, reached the boundary with the overlying sulfidic zone.

Continuous-Flow Stable Sulfur Isotope Analysis of Organic and Inorganic Compounds by EA-MC-ICPMS.

Elemental analysis (EA) coupled to isotope ratio mass spectrometry (IRMS) is a well-established method to derive stable isotope ratios of sulfur (34S/32S). Conversion of sulfur to SO2 by EA and measurement of SO2 isotopologues by IRMS represents the simplest and most versatile method to accomplish isotope measurement of sulfur even in bulk samples. Yet, interferences by oxygen isotopes in SO2 often impair the precision and trueness of measured results. In the current study, we coupled EA to multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) to establish a method that avoids such interferences due to direct measurement of S+ ions. In addition, measurement of the 33S/32S isotope ratios is possible, thus representing the first bulk method that is suitable to study mass-independent isotope fractionation (MIF). Analytical precision (σ) of available Ag2S and BaSO4 reference materials (RMs) was, on average, 0.2 mUr for δ33S and δ34S, never exceeding 0.3 mUr within this study (1 mUr = 1‰ = 0.001). Measured δ34S values of reference materials agreed within ±0.2 mUr of officially reported values. Measurement of wood samples yielded good precision (0.2 mUr) for sulfur amounts as low as 3.5 μg, but precision deteriorated for samples at lower sulfur contents due to poor peak shape. Finally, we explored cross-calibration of organic liquids separated via gas chromatography (GC) against solid RMs combusted via EA that avoids challenging offline conversion of RMs. Results indicate good precision (≤0.08 mUr) and acceptable trueness (≤0.34 mUr) for determination of δ34S, demonstrating the future potential of such an approach.

Geology and Geochronology of Magmatic–Hydrothermal Breccia Pipes in the Yixingzhai Gold Deposit: Implications for Ore Genesis and Regional Exploration

Magmatic–hydrothermal breccia pipes are widespread in numerous major porphyry and epithermal gold deposits globally, representing significant repositories of metal resources and serving as potential indicators for exploration targeting. More than ten breccia pipes occur in the Central Taihangshan District (CTD) of the North China Craton. Some of these breccia pipes host gold mineralization and are proposed to be related to the adjacent lode gold mineralization. However, the lack of detailed geological constraints make this hypothesis ambiguous. To address this, the present study conducted comprehensive field observations, drill core logging, an in situ sulfur isotope analysis of pyrite, and the 40Ar/39Ar dating of adularia along a 1400 m section of the Tietangdong breccia pipe at Yixingzhai. Three distinct breccia facies were identified at Tietangdong, exhibiting variable proportions across the entire section, including a massive skarn breccia; polymictic, skarn matrix-supported breccia; and polymictic, intrusive rock cement chaotic breccia. Furthermore, adularia 40Ar/39Ar dating indicates a syn-/post-gold mineralization age of 136 ± 1.5 Ma, coinciding with the age of post-breccia felsite dike. The deepest sampled pyrite displays δ34S values of ~2.7‰, strongly indicating a magmatic–hydrothermal signature. These results, when combined with the geological, geochronological, and isotopic studies on the adjacent lode gold mineralization, further suggest a close genetic relationship between the breccia pipes and the lode Au mineralization, paving the way for their utilization as effective indicators for gold targeting within the CTD.

Isotopic evidence of high reliance on plant food among Later Stone Age hunter-gatherers at Taforalt, Morocco

The transition from hunting-gathering to agriculture stands as one of the most important dietary revolutions in human history. Yet, due to a scarcity of well-preserved human remains from Pleistocene sites, little is known about the dietary practices of pre-agricultural human groups. Here we present the isotopic evidence of pronounced plant reliance among Late Stone Age hunter-gatherers from North Africa (15,000–13,000 cal BP), predating the advent of agriculture by several millennia. Employing a comprehensive multi-isotopic approach, we conducted zinc (δ66Zn) and strontium (87Sr/86Sr) analysis on dental enamel, bulk carbon (δ13C) and nitrogen (δ15N) and sulfur (δ34S) isotope analysis on dentin and bone collagen, and single amino acid analysis on human and faunal remains from Taforalt (Morocco). Our results unequivocally demonstrate a substantial plant-based component in the diets of these hunter-gatherers. This distinct dietary pattern challenges the prevailing notion of high reliance on animal proteins among pre-agricultural human groups. It also raises intriguing questions surrounding the absence of agricultural development in North Africa during the early Holocene. This study underscores the importance of investigating dietary practices during the transition to agriculture and provides insights into the complexities of human subsistence strategies across different regions.

Local depositional and diagenetic conditions control the positive δ34S excursion during the Ordovician-Silurian transition: Evidence from the Wufeng-Longmaxi formations in Sichuan Basin

The Ordovician-Silurian (OS) transition was characterized by significant changes in global climate, marine redox conditions, and biological evolution, which include global seawater euxinia, the onset of the Hirnantian glaciation, and large-scale extinctions. During this time, the marine sulfur cycle was disrupted, and the pyrite sulfur isotope (δ34Spy) showed a large positive excursion. This excursion is closely tied to the Hirnantian glaciation, with δ34Spy increasing at the start of and decreasing at the end of the glaciation. Although it is thought that variations in marine sulfate concentration and primary productivity are responsible for the positive excursion in δ34Spy, contemporary marine sediment δ34Spy data suggest that sedimentary processes can also lead to significant fluctuations in δ34Spy. To assess the impact of local changes in sedimentary conditions on this positive δ34Spy excursion event, we conducted detailed depositional and geochemical analyses of sedimentary pyrite found in black shales from the Wufeng-Longmaxi formations in the Weiyuan area of the Sichuan Basin, China. These sedimentary pyrites include three types: framboidal, euhedral, and laminated pyrite. Bulk sample sulfur isotope analyses revealed that δ34Spy values vary from −16.2‰ to 15.8‰ (mean = −3.8‰, n = 22). In situ analyses of δ34Spy show that different pyrite crystals exhibit a range of intragranular δ34Spy values that are likely indicators of diagenesis. Variations in bulk sample δ34Spy are strongly and negatively correlated with the proportion of framboidal pyrite, i.e., lower levels of framboidal pyrite content resulted in a higher bulk sample δ34Spy value, suggesting diagenetic alteration controls on δ34Spy. In addition, the δ34Spy excursion in the Wufeng-Longmaxi formations also appears to be compatible with lithological changes related to sedimentation rate. The δ34Spy values from the Guanyinqiao Bed, which consists of calcareous shales, are higher than those from black shales with a relatively low sedimentation rate. Our results suggest that the positive δ34Spy excursion during the OS transition during the Hirnantian glaciation is controlled not only by diagenetic alterations but also by local sedimentation rate.

Origin and evolution of a porphyry-skarn-stratabound system: constraints from geology, magmatic-hydrothermal zircon U–Pb and molybdenite Re–Os geochronology, and in situ S isotopes of the Dongguashan Cu(–Au) deposit, eastern China

Intrusion-related stratabound deposits within Late Carboniferous carbonate units are an abundant and highly economically significant ore type in eastern China. In such deposits, stratabound mineralization commonly coexists with porphyry and/or skarn mineralization, and the vast majority of reserves (>90 %) are derived from extensive stratabound orebodies, which are easy to exploit and of great interest to geologists. However, it is unclear whether these deposits were formed via the Late Carboniferous seafloor sedimentary exhalation formation or the Early Cretaceous magmatic-hydrothermal processes. Moreover, the fluid and sulfur isotope variations within porphyry-skarn-stratabound systems have not been adequately constrained. We investigated the Dongguashan deposit, one of the largest and most representative stratabound Cu(–Au) deposits in eastern China. Three mineralization types were recognized based on field and petrologic studies: porphyry, skarn, and stratabound. In the stratabound mineralization zone, magmatic and hydrothermal zircons from laminated ores yielded concordant U–Pb ages of 137.3 ± 1.1 and 135.7 ± 1.4 Ma, respectively, while molybdenite samples from vein-like ores yielded Re–Os model ages of 137.8–133.1 Ma (isochron age, 135.9 ± 1.4 Ma). These ages were consistent with the zircon U–Pb age of quartz monzodiorite (137.8 ± 1.7 Ma). A total of 146 in situ S isotope analyses yielded δ34S values (1.9–7.4 ‰) indicating that the sulfur was derived from a magmatic source. Therefore, the Dongguashan deposit resulted from Early Cretaceous magmatism rather than submarine exhalative sedimentary processes. The fluctuations in S isotopes of sulfides across the three mineralization types are attributable to different factors (pH, temperature, and oxygen fugacity) during the evolution of hydrothermal ore-forming fluids. This study demonstrates the importance of geochronology of mineralization and in situ sulfur isotope analysis under robust geological and petrographic frameworks, which can yield information about the ore-forming processes and ore genesis.

Decadal-to-centennial increases of volcanic aerosols from Iceland challenge the concept of a Medieval Quiet Period

AbstractExisting global volcanic radiative aerosol forcing estimates portray the period 700 to 1000 as volcanically quiescent, void of major volcanic eruptions. However, this disagrees with proximal Icelandic geological records and regional Greenland ice-core records of sulfate. Here, we use cryptotephra analyses, high-resolution sulfur isotope analyses, and glaciochemical volcanic tracers on an array of Greenland ice cores to characterise volcanic activity and climatically important sulfuric aerosols across the period 700 to 1000. We identify a prolonged episode of volcanic sulfur dioxide emissions (751–940) dominated by Icelandic volcanism, that we term the Icelandic Active Period. This period commences with the Hrafnkatla episode (751–763), which coincided with strong winter cooling anomalies across Europe. This study reveals an important contribution of prolonged volcanic sulfate emissions to the pre-industrial atmospheric aerosol burden, currently not considered in existing forcing estimates, and highlights the need for further research to disentangle their associated climate feedbacks.

Procedures from samples to sulfur isotopic data: A review.

Sulfur isotopes have been widely used to solve some key scientific questions, especially in the last two decades with advanced instruments and analytical schemes. Different sulfur speciation and multiple isotopes analyzed in laboratories worldwide and in situ microanalysis have also been reported in many articles. However, methods of sampling to measurements are multifarious, and occasionally some inaccuracies are present in published papers. Vague methods may mislead newcomers to the field, puzzle readers, or lead to incorrect data-based correlations. We have reviewed multiple methods on sulfur isotopic analyses from the perspectives of sampling, laboratory work, and instrumental analysis in order to help reduce operational inhomogeneity and ensure the fidelity of sulfur isotopic data. We do not deem our proposed solutions as the ultimate standard methods but as a lead-in to the overall introduction and summary of the current methods used. It has been shown that external contamination and transformation of different sulfur species should be avoided during the sampling, pretreatment, storage, and chemical treatment processes. Conversion rates and sulfur isotopic fractionations during sulfur extraction, purification, and conversion processes must be verified by researchers using standard or known samples. The unification of absence of isotopic fractionation is needed during all steps, and long-term monitoring of standard samples is recommended. This review compiles more details on different methods in sampling, laboratory operation, and measurement of sulfur isotopes, which is beneficial for researchers' better practice in laboratories. Microanalyses and molecular studies are the frontier techniques that compare the bulk sample with the elemental analysis/continuous flow-gas source stable isotope ratio mass spectrometry method, but the latter is widely used. The development of sulfur isotopic measurements will lead to the innovation in scientific issues with sulfur proxies.

The genesis of the Baguamiao orogenic gold deposit linked to multistage ore-forming processes in Triassic tectonic transition of South Qinling, China

The Baguamiao gold deposit represents one of the largest Triassic orogenic gold deposits in the South Qinling metallogenic belt of central China. Here we investigate Ar-Ar dating of sericite and muscovite, fluid inclusion of quartz, the trace element and sulfur isotopic composition of pyrite from different mineralization stage in the Baguamiao gold deposit to gain insights into the ore genesis. The Ar-Ar dating results yield 40Ar/39Ar plateau ages of 217.5 ± 2.1 Ma, 209.2 ± 0.2 Ma and 208.8 ± 0.2 Ma, indicating a two-stage gold mineralization during the tectonic transition from the early metamorphic deformation (at ca. 218 Ma) to the late extension (ca. 209 Ma) in the post-collision environment. Fluid inclusion, trace element and sulfur isotopic analyses reveal that the two stages gold mineralization show different sources. The early mineralization period developed CO2-rich inclusions with medium temperature (317–413 °C) and medium–low salinity (4.62–18.81 wt% NaCleqv.), and is characterized by formation of Py1 and Py2 with depleted Au, Cu, Pb, Zn, Ag, Te and Bi. The sulfur isotope data of Py1 and Py2 are between 3.6 ∼ 10.5 ‰, suggesting that the sulfur source was mainly derived from the surrounding rock (Xinghongpu Group). The late mineralization period developed medium–high temperature (321–453 °C), medium–high salinity (3.3–19.62 wt% NaCleqv.) CO2-rich inclusions and high-temperature and high-salinity daughter crystal inclusions, and is characterized by formation of Py3 and Py4 with obviously higher arsenic and metal contents, such as Au, As, Cu, Pb, Zn, Ag, Cr, Ti, Mn, Sb. The δ34S values of Py3 and Py4 are 8.3 ∼ 18.8 ‰, suggesting a mixed fluid of the Xinghongpu Group and Gudaoling Group with deep magmatic-hydrothermal fluids. We propose that the two periods of gold mineralization in the Baguamiao deposit, in response to the collision assembly of Qinling Orogenic Belt, preserve evidence for diverse metal sources with the early mineralization period sourced from the metamorphism of the upper crust (Xinghongpu Group) in the compressional stage (ca. 218 Ma), and the late mineralization period characterized by the contribution of the Xinghongpu Group, Gudaoling Group and deep magmatic-hydrothermal fluids in a post-collisional extensional setting (ca. 209 Ma). The role of metamorphism and magmatic activity during the Triassic Qinling orogenic processes is considered to be important in the remobilization, transport and enrichment of sulfur, arsenic and gold (and potentially other trace elements) from the earlier formed seafloor exhalation sequence.

Gold mineralisation by pyrite recrystallisation and arsenopyrite sequestration in the Jiaochong Au deposit, Tongling ore district, eastern China: Implications for the formation of stratabound ore deposits

The Middle–Lower Yangtze River Valley metallogenetic belt (MLYRB) is a large and economically valuable porphyry–skarn Cu–Au ore belt in China with a total reserve of >600 tonnes of gold. Orebodies in the MLYRB are commonly stratabound and extend for several tens of metres in length and locally for more than 1000 m. However, the origin of the stratabound orebodies is uncertain, with proposals including a magmatic or sedimentary genesis, and the specific processes by which these gold deposits were formed are also unclear. Here we report a study of the representative stratabound Jiaochong Au deposit in the Tongling ore district, where stratified gold orebodies are hosted at the Triassic -Permian strata boundary. A detailed field survey, petrologic observations, in situ sulfur isotopic analysis, and major and trace element compositional analysis of gold and sulfide grains were carried out to determine how the gold was enriched. Field survey shows that precipitated sulphides exhibit obvious mineral and textural zonation from wall-rock to orebody centres as follows: Zone 1, colloform pyrite (Py1) ± sphalerite ± chalcopyrite → Zone 2, euhedral pyrite (Py2) ± pyrrhotite + arsenopyrite ± colloform pyrite (Py1) → Zone 3, pyrrhotite + arsenopyrite. From zone 1 to zone 3, the sulphides were progressively phase-transformed, with the earlier Py1 being gradually consumed and converted into Py2, which finally became pyrrhotite. The gold deposition occurs in Zones 2 and 3 and forms two generations of gold grains, one group being completely enclosed within euhedral Py2 with low As contents (<0.1 wt%) and another group infilling fractures between arsenopyrite and pyrrhotite or occurring as inclusions within arsenopyrite with high As contents (0.4 to 1.4 wt%). The comparable S-isotope compositions of the ore sulfides to those of Mesozoic intermediate-felsic intrusions and the veining characteristics of colloform pyrite in the Tongling ore district suggest that Mesozoic magmatic-hydrothermal fluids, rather than Carboniferous sedimentary rocks as usually thought, provided the principal ore-forming materials. The gold precipitation in this study followed two continuous processes: recrystallisation and arsenopyrite sequestration; in the first process, Au is remobilised from the pyrite structure at higher temperatures up to recrystallisation of fine-grained, colloform morphologies into euhedral crystals and formation of Au-bearing metallic particles (Au1); with the ongoing recrystallisation more As is released and accumulated into the equilibrated fluids, forming As-rich pyrite or arsenopyrite and a second period of gold deposition (Au2). The continuous sulphide zonation texture and phase transformation, similar to Jiaochong, have been observed in other gold deposits in the MLYRB, and our gold enrichment processes may also give an explanation for the formation of these stratabound gold deposits.

In situ trace element and sulfur isotopic analysis of multi-stage pyrite in Mingsai gold deposit, southern Tibet: Insights into mineralization and gold remobilization

Pyrite is the main gold-bearing mineral and can provide information about the formation of gold deposits. This study focuses on the Mingsai gold deposit, a newly discovered deposit in the east of the Tethyan Himalayan Sequence. We analyzed the texture, composition, and formation process of pyrite in the deposit to understand how gold was formed. We identified five types of pyrite: diagenetic pyrite (Py0), pre-ore stage pyrite (Py1), gold-rich pyrite (Py2a and Py2b), and post-stage pyrite (Py3). All of these types contain varying amounts of “invisible” gold. Py0 is framboidal pyrite enriched in certain elements but depleted in gold. It has high δ34S values (mean 10.75 ‰). Py1 has a porous structure and contains silicate inclusions. It has low gold content and high Co/Ni ratios. The δ34S values of Py1 cluster around ∼ 0 ‰. Py2a is subhedral-euhedral pyrite found in the middle of disseminated pyrite and quartz-carbonate-sulfide veins. It has abundant gold (0.16 – 103 ppm) and relatively low δ34S (1.17 ‰ – 3.50 ‰). Py2b occurs as the rim of disseminated pyrite and sulfide inclusions at the interface with Py2a. It has lower gold content (0.90 – 9.85 ppm) and distinctly high δ34S (6.58 ‰ – 8.87 ‰) compared to Py2a. Py3 is vein-like pyrite in metamorphic tuff, which does not contain significant amounts of gold (Au < 1 ppm) and has higher δ34S values (9.86 ‰ – 11.69 ‰) than Py2b. The concentrations of metal elements, including gold, in Py2b are intermediate between those of Py2a and Py3. The researchers propose that Py2a is the main source of gold, and Py2b is a mixture of Py2a and Py3. During the mixing process, gold is released from Py2a and re-precipitates in Py2b through dissolution-reprecipitation reactions. The sulfur isotope composition suggests that the materials that formed Py2a (∼2‰) may have originated from magmatic-hydrothermal sources and undergone transformation. The detailed geochemical evidence indicates a close connection between the Mingsai gold deposit and other gold-antimony deposits in the Zhaxikang ore district, which are likely related to early Miocene magmatism in the Cuonadong dome.

Neolithisation through bone: Stable isotope analysis of human and faunal remains from Syltholm II, Lolland, Denmark

Despite an increasing number of studies, the application of stable sulfur (δ34S) isotope analysis to prehistoric bone collagen remains in its infancy. Conventionally, stable sulfur isotope compositions reflect coastal proximity and the interaction between humans and animals. Here, we undertook stable carbon (δ13C), nitrogen (δ15N) and sulfur (δ34S) isotope analysis of human and faunal bone collagen. To understand the local environmental conditions as well as the husbandry regime employed by the first farmers, and investigate where the animals were raised or hunted in non-specific terms, we sampled 50 faunal, including wild and domestic taxa, and human remains from the Late Mesolithic to Early-Middle Neolithic (c. 4860–2310 cal BC) site of Syltholm II on the island of Lolland, Denmark. We show that the wild animals were obtained from multiple locations surrounding the prehistoric Syltholm Fjord, including forested and open landscapes, areas impacted by sea spray and saltmarshes. In contrast, the domestic taxa, especially cattle, were tightly managed for the majority of their lives based on their δ13C and δ15N isotope compositions, though were likely raised in multiple locations, including sea spray-affected areas, saltmarshes and wetlands, based on their δ34S values. The domestic dogs had a broad range of δ13C, δ15N and δ34S values, reflecting the consumption of varying degrees of marine foodstuffs, including animals that were sulfide-derived. Overall, our results contribute to a growing body of evidence for possible cultural and animal husbandry duality during the earliest Neolithic in southern Scandinavia.

Atmospheric ozone destruction and the end-Permian crisis: Evidence from multiple sulfur isotopes

The end-Permian mass extinction (EPME) is considered the largest biotic crisis of the Phanerozoic. To explain the worldwide destruction and mutation of land plants, previous work has emphasized the role of enhanced UV irradiation linked to volcanism-induced disruption of the ozone shield. However, direct evidence for a link between volcanic SO2 emission and stratospheric ozone deterioration is missing. Previous bulk analysis (i.e., SF6 method) found no Mass-Independent Fractionation of sulfur isotopes (MIF-S, noted Δ33S). However, possible grain scale sulfur isotope anomaly can be easily overlooked during bulk analysis. To detect possible sulfur isotope anomaly in grain scale, we applied in-situ multiple sulfur isotope analysis of the sulfide using secondary ion mass spectrometry (SIMS). We found a marked positive shift (higher than +0.30‰ and up to +0.94‰) just before the end-Permian extinction in the Meishan section. Modelling shows that these positive Δ33S anomalies cannot be explained by Mass Dependent Fractionation (MDF) processes alone, rather by UV-induced photolysis of volcanic SO2. The formation and preservation of MIF-S anomalies in the atmosphere and subsequent transport to the oceans require intense and prolonged irradiation of the Earth's surface with solar UV, thus fingerprinting severe disruption of the atmospheric ozone balance at the onset of Earth's largest mass extinction.

A synthesized sphalerite standard for in situ analysis of sulfur isotopes and trace elements by LA-MC-ICP-MS and LA-ICP-MS

A synthesized sphalerite bulk Sph-LD is recommended as a potential reference material for S isotope and trace element analysis employing LA-MC-ICP-MS and LA-ICP-MS.

Comparative study on metallogeny of the mesozonal Mingsai and epizonal Mazhala gold deposits, southern Tibet: Constraints from geology, in-situ trace element, and sulfur isotope analysis of sulfides

Comparative study on metallogeny of the mesozonal Mingsai and epizonal Mazhala gold deposits, southern Tibet: Constraints from geology, in-situ trace element, and sulfur isotope analysis of sulfides

In situ sulfur isotope analysis of pyrite from the Ezuri Kuroko‐type volcanogenic massive sulfide deposit, northeastern Japan: Contribution of microbial sulfate reduction to initial sulfide mineralization

AbstractVolcanogenic massive sulfide (VMS) deposits are ancient analogues of seafloor massive sulfide (SMS) deposits. The importance and contribution of microbial activity during initial mineralization has recently been recognized in both VMS and SMS deposits. Here, we report in situ sulfur isotope compositions (δ34S) of pyrite from the Ezuri Kuroko‐type VMS deposit in northeastern Japan as determined by secondary ion mass spectrometry. During the evolutionary process of sulfide mineralization, pyrite textures changed from framboidal to colloform to euhedral. Initial framboidal pyrite had highly negative δ34S values down to −31.8‰ (average ± 1SD = −18.8‰ ± 13.0‰; n = 21), banded colloform pyrite exhibited medium δ34S values (−11.7‰ ± 10.4‰; n = 8), and euhedral pyrite displayed the highest average δ34S value of +2.7‰ ± 1.6‰ (n = 5); thus, δ34S varied as different textures of pyrite were produced during mineralization. The maximum isotopic fractionation between framboidal pyrite and past seawater sulfate (δ34S ca. +20‰) is −52‰; such values can be produced only by microbial sulfate reduction (MSR) in an open system. Framboidal pyrite with a low δ34S value is observed at the centers of sulfide‐rich areas within polished sections and has often been replaced by later sulfide minerals (sphalerite, galena, and chalcopyrite); thus, our S isotope data from the Ezuri pyrite reveal that sulfur derived from MSR induced and acted as a nucleation point for later sulfide mineral growth. Combined with previously reported data, our results endorse the importance and universality of MSR‐derived sulfur during the initial mineralization stage of both VMS and SMS deposits.

Sulfur isotopic analysis of sedimentary pyrite at micro-nano scale and its implications to oil/gas generation in the Dongying Depression

Sulfur isotopic analysis of sedimentary pyrite at micro-nano scale and its implications to oil/gas generation in the Dongying Depression

Mineralogical Characteristics and Genetic Types of Pyrite with Different Occurrence: Constraints from Spectroscopy, Geochemistry and δ34S Stable Isotopes

Pyrite is widely distributed in the Earth’s crust and oceanic systems, and it generally occurs as pentagonal dodecahedra, cubic, octahedral, idiomorphic crystals, or dense, massive, granular, and nodular aggregates. In this study, representative pyrite samples from Hunan, Fujian, Jiangxi, Anhui in China and from Peru were collected. By utilizing a range of analytical techniques, including petrography, X-ray diffraction, infrared spectrum, Raman spectrum, major and trace element analysis, as well as sulfur stable isotope analysis, we comprehensively depict the mineralogical and spectroscopic characteristics of pyrite, and the evolution processes of the physical and chemical conditions of mineralization can be qualitatively constrained. The spectroscopic results indicate all samples show a relatively narrow absorption band with weak to moderate intensity in the vicinity of 343 cm−1, which represents the bending vibration of the Fe-[S2]2− molecular bond. The Co content of pyrite exhibits the characteristics of a positive correlation with temperature and a negative correlation with oxygen fugacity, respectively. The δ34S isotopic compositions of colloidal pyrite are in the range of 0.03 to 0.67, which are close to meteoric sulfur and mantle sulfur compositions, while the δ34S values of nodular pyrite fall within the range of granite, indicating the characteristics of mixtures of sulfur sources are mainly related to magmatic activity. Our results provide insight into the formation mechanisms of pyrite in different environments, its mineralization, and the ore genesis of deposits. Moreover, the integrated analytical methods for pyrite are provided, which can define theoretical guidance for the exploration and development of mineral resources.

Sex Determination and Isotopic Analysis of the Nivåfjord Mesolithic Burials, Zealand, Denmark

Since 1992 the prehistoric Nivåfjord in northeast Zealand, Denmark, has yielded an appreciable number of inhumation burials and cremations dating to the Mesolithic, especially the sites of Nivå 10 and Nivågård. Unfortunately, the micro-region is characterised by poor organic preservation, restricting the successful application of biomolecular techniques to human remains, including large-scale radiocarbon dating programmes as well as both stable isotope and ancient DNA analyses. Here, we apply an alternative technique, an acid etch peptide-based method, to determine the sex of eight individuals from Nivå 10 as well as the Nivågård child. Moreover, we revisit the utility of stable carbon (δ13C), nitrogen (δ15N) and sulfur (δ34S) isotope analysis of human tissues to reconstruct the life histories and diets of 10 individuals from Nivå 10 as well as the Nivågård child. To contextualise further, we sampled 14 Capreolus capreolus and three Sus scrofa from the Nivågård site for stable isotope analysis. We demonstrate that sex can successfully be determined from contexts susceptible to poor organic preservation, and show that the Nivågård child spent a proportion of its life outside a sea spray-influenced environment, and consumed significant quantities of marine protein as demonstrated by its δ13C and δ34S values.