Range Of δ13C Values Research Articles

Stable isotope analysis of faunal remains from Bronze Age Kaymakçı, Western Anatolia

This paper presents the results of stable carbon ( δ13C) and nitrogen ( δ15N) isotopic analysis of bulk bone collagen from faunal remains from the Bronze Age site of Kaymakçı in western Anatolia. We use the isotopic values in conjunction with zooarchaeological data and contextual archaeological information to examine human-environment interactions; in particular, animal management and husbandry. Middle and Late Bronze Age agricultural systems in western and central Anatolia remain poorly understood, and this research aims to contribute to rectifying this research gap. We obtained stable isotopic values from both wild and domestic species, including deer, hare, birds, catfish, dogs, pigs, caprids and cattle. The δ13C values range from −22.0‰ to −16.9‰ and the δ15N values range from 2.3‰ to 10.3‰. For cattle, the δ13C values suggest that some specimens were subject to different management strategies, likely related to feeding or herding patterns or even the movement of animals in and around the region through some exchange mechanism. There appears to be no fixed location or strategy for the management of caprids and, furthermore, there is evidence to suggest that the herding/management areas of some caprids overlapped with those of wild animals such as deer and hare. Variation in δ15N values for pigs may indicate that whilst some animals in the sampled assemblage were free-roaming, others were penned. For the pigs and some other herbivorous domesticated species variation in δ15N values may also point to the exploitation of the wetland areas around Lake Marmara.

Stable isotope analysis of western Lake Superior predatory fishes, part one: Trophic niche overlap

Characterizing food web interactions between introduced and native fish predators is important to quantify niche overlap, assess predator–prey balance, and support fisheries management. Lake Superior provides an ideal setting to investigate potential trophic overlap between native top predators, lake trout (Salvelinus namaycush) and walleye (Sander vitreus), and a diverse assemblage of introduced salmonids. Angler-caught fish were used to measure trophic position and niche overlap between predatory fishes in the western arm of Lake Superior based on carbon and nitrogen stable isotope ratios (δ13C, δ15N). Within a species, we did not find consistent differences in either δ13C or δ15N values by sex, collection year, capture location, or length. Among species, the range in δ15N values was >5 ‰, indicating that these species occupy ∼2 trophic positions, with dietary reliance ranging from primarily invertebrates to primarily fish, whereas the range in δ13C values indicated dietary reliance on a mix of pelagic and benthic prey. Combined, the δ13C and δ15N values revealed siscowet lake trout as the apex predator having a distinct trophic niche, while walleye and lean lake trout were intermediate trophic position predators with overlapping isotopic niches, and introduced salmonids were the lowest trophic position predators with overlapping trophic niches. Overlapping trophic niches indicated similar resource reliance and habitat occupancy among native lake trout and walleye, as well as among introduced salmonids, but less so between native and introduced predators.

Stable isotope analysis of Late Pleistocene mammalian teeth from western, central, and north-central India and the associated Palaeolithic archaeology of the Indian Subcontinent

The oxygen (δ18O) and carbon (δ13C) ratios in bioapatite from dental tissues of fossil mammals are well-established proxies for climatic conditions and dietary patterns. In the present study, a total of 24 Late Pleistocene mammalian teeth belonging to Cervid, Bovid, Suid, Hippopotamid, Canid, Equid from Gopnath in Gujarat, ten separate localities from the Narmada Basin, and one in Son River Basin, India were analysed for δ13C and δ18O values to understand palaeoclimatic conditions and associated dietary habits between marine isotope stages (MIS) 5 and 3 as estimated from stratigraphic and archaeological record. The δ13C values in the samples of Gopnath, Narsinghpur and Doma range from −3.1 to 2.3 ‰, −3.2 to 1.3 ‰, and −2.0 ‰, respectively. The higher δ13C values in these specimens suggest a diet based predominantly on C4 plants. On the other hand, a relatively lower and large range of δ13C values from Nehlai (−11.1 to −3.5 ‰) suggests a predominately C3 to mixed C3-C4 diet. The δ18O values in Gopnath, Nehlai, Narsinghpur and Doma are −4.1 to −3.1 ‰, −4.7 to −2.1 ‰, −4.0 to −1.9 ‰ and −5.8 ‰, respectively. The relatively lower δ18O value points towards humid climatic conditions and the relatively higher δ18O values suggest relatively arid climatic conditions. The regional contexts are dominated by Late Pleistocene geological records predominantly associated with Middle Palaeolithic evidence, and the preliminary isotope results indicate that contemporary hominin groups occupied warm and semi-humid environments. This study attempts to examine the Late Pleistocene environments and hominin adaptations across western, central, and north-central India on a comprehensive scale.

High–precision determination of carbon stable isotope in silicate glasses by secondary ion mass spectrometry: Evaluation of international reference materials

Secondary ion mass spectrometry (SIMS) has been used for isotope analysis of volatile components dissolved in silicate melts for decades. However, carbon in situ stable isotope analysis in natural silicate glasses has remained particularly challenging, with the few published attempts yielding high uncertainties. In this context, we characterized 31 reference silicate glasses of basaltic and basanitic compositions, which we then used as reference materials to calibrate δ13C − value analyses in silicate glasses by SIMS. This set of reference materials covers a wide range of CO2 concentrations (380 ppm – 12,000 ppm) and δ13C values (−28.1 ± 0.2 to −1.1 ± 0.2 ‰, ±1σ). The sets of reference materials were analyzed using large−geometry SIMS at two ion microprobe facilities to test reproducibility across different instrumental setups. The instrumental mass fractionation (IMF) varied widely with two different large−geometry SIMS instruments as well as with different analytical parameters such as field aperture size and primary beam intensity. We found that a precision better than ±1.1 ‰ (both average internal and external precision, ±1σ) for CO2 content higher than 1800 ppm could be achieved using a primary beam intensity of less than 5 nA, resulting in a final spot size of 10–20 μm, allowing precise analysis of δ13C in mineral−hosted melt inclusions. This level of precision was achieved at CO2 concentrations as low as 1800 ppm. This advance opens a wide range of new possibilities for the study of δ13C − value in mafic melts and their mantle sources. The reference materials are now available at the CNRS–CRPG ion microprobe facility in Nancy, France and will be deposited at the Smithsonian National Museum of Natural History, Washington, USA where they will be freely available on loan to any researcher.

Isotope-based inferences of the trophic niche of short-finned pilot whales in the Webbnesia

Knowledge of predator-prey interactions is key in ecological studies and understanding ecosystem function, yet this is still poorly explored in the deep-sea environment. Carbon (δ13C: 13C/12C) and nitrogen (δ15N: 15N/14N) stable isotope ratios of a deep-diving species, the short-finned pilot whale (Globicephala macrorhynchus), were used to explore knowledge gaps on its ecological niche and foraging habitats in the Webbnesia marine ecoregion (Tenerife Island, n = 27 animals vs. Madeira, n = 31; 500 km apart) where animals display distinct levels of site fidelity. Specifically, we tested whether intraspecific isotopic variation results from differences between geographic areas (due to possible foraging plasticity between regions), sexes, and/or years (2015–2020) using Generalized Linear Models. In general, significant differences (p < 0.05) were found in the stable isotope profiles of pilot whales between the two archipelagos, which were also reflected in their isotopic niche. The higher mean and wider range of δ15N values in Tenerife suggest that pilot whales consume prey of higher trophic levels and more diverse than Madeira. The higher mean and wider range of δ13C values in Madeira suggest that in that island, pilot whales rely on prey from more diverse habitats. There was significant variation between some years, but not between sexes. Finally, we discuss pilot whales' foraging strategies worldwide and infer the reliance on benthic or benthopelagic food sources in the Webbnesia.

Feeding ecology of Chaeturichthys stigmatias during autumn in Haizhou Bay

Research about feeding ecology of fish is important to understand individual behavior and population development, which is also the basic to analyze trophic structure and function of aquatic ecosystems. Chaetrichthys stigmatias is one of the key species in the Haizhou Bay fisheries ecosystem, which has critical ecological niche within the food web. In this study, we collected samples through bottom trawl surveys during the fall of 2018 in the Haizhou Bay, and analyzed the feeding ecology of C. stigmatias based on both stomach content analysis and stable isotope technology. The results showed that the primary diet groups for C. stigmatias were Ophiuroidea and Shrimp, including Ophiothrix marenzelleri, Ophiopholis mirabilis, Ophiura sarsii, Penaeidae, and Alpheus japonicus. The range of δ13C values of C. stigmatias was from -19.39‰ to -15.74‰, with an average value of (-18.07±0.87)‰, which had no significant correlation with body length. The range of δ15N values was from 8.16‰ to 12.86‰, with an average value of (10.14±1.51)‰, which was positively correlated with body length. The trophic level of C. stigmatias showed a positive relationship with body length, with an average value of (3.74±0.34) and a range value of 3.32 to 4.20 among different size groups. The contribution rates of different prey groups varied significantly. Based on the structural equation modeling, we found that the feeding intensity of C. stigmatias was primally influenced by body length, sea bottom salinity, sea bottom temperature, and water depth, with a particularly signi-ficant positive correlation with body length. The combination of stable isotope technology and stomach content analysis methods could contribute to comprehensive understanding on the feeding ecology of C. stigmatias, providing essential data and foundation for research on trophic structures and resource conservation in the Haizhou Bay ecosystem.

Using Multi‐Homolog Plant‐Wax Carbon Isotope Compositions to Reconstruct Tropical Vegetation Types

AbstractThe stable carbon isotope composition (δ13C) of plant components such as plant wax biomarkers is an important tool for reconstructing past vegetation. Plant wax δ13C is mainly controlled by photosynthetic pathways, allowing for the differentiation of C4 tropical grasses and C3 forests. Proxy interpretations are however complicated by additional factors such as aridity, vegetation density, elevation, and the considerable δ13C variability found among C3 plant species. Moreover, studies on plant wax δ13C in tropical soils and plants have focused on Africa, while structurally different South American savannas, shrublands and rainforests remain understudied. Here, we analyze the δ13C composition of long‐chain n‐alkanes and fatty acids from tropical South American soils and leaf litter to assess the isotopic variability in each vegetation type and to investigate the influence of climatic features on δ13C. Rainforests and open vegetation types show distinct values, with rainforests having a narrow range of low δ13C values (n‐C29 alkane: ‰ ; Suess‐effect corrected). This allows for the detection of even minor incursions of savanna (δ13C n‐C29 alkane ‰) into rainforests. While Cerrado savannas and semi‐arid Caatinga shrublands grow under distinctly different climates, they can yield indistinct δ13C values for most compounds. Cerrado soils and litter show pronounced isotopic spreads between the n‐C33 and n‐C29 alkanes, while Caatinga shrublands show consistent values across the two homologs, thereby enabling the differentiation of these vegetation types. The same multi‐homolog isotope analysis can be extended to differentiate African shrublands from savannas.

Long-term variations in terrestrial carbon cycles and atmospheric CO2 levels: Exploring impacts on global ecosystem and climate in the aftermath of end-Cretaceous mass extinction

The short-term climate and environmental consequences (<∼1.0–10 Kyr) immediately following the end-Cretaceous extinction have been attributed to transient effects originating from Deccan volcanism and the Chicxulub impact. These two events have received significant attention for their role in precipitating extreme climate conditions. In contrast, the long-term (> ∼100 Kyr) climate and environmental changes of the post-extinction have been extensively studied in the marine systems, yet their ramifications within terrestrial ecosystems are less well-characterized and require further elucidation. This study presents a carbon isotope analysis of pedogenic carbonates from matured calcisols in the Nanxiong Basin, South China, to reconstruct carbon cycles and atmospheric CO2 concentrations (pCO2) spanning from 76.0 Ma to 62.0 Ma, aiming to decipher the long-term terrestrial environmental and climatic conditions. Results show that δ13C values range from −12.4‰ to −5.0‰ (mean − 9.0‰) and pCO2 varies between ∼250 ppmV and ∼ 2200 ppmV (mean 920 ppmV). When combined with δ13C data from Songliao Basin, NE China, the carbon cycle variation exhibits a 13C collapse and smooth towards subsequent rebound, indicating a process of ∼600 Kyr deterioration, ∼600 Kyr stabilization and ∼ 400 Kyr recovery in the terrestrial ecosystem. The fluctuation of estimated pCO2 aligns with the change pattern of sea surface temperatures, attesting to the strong perturbation of climate and environment at the same pace as the carbon cycle variations. It is proposed that ecosystems and environments in both terrestrial and surface ocean experienced a more unstable, difficult and erratic recovery process and were much more sensitive to climatic changes than in deep ocean for ∼1.5 million years in the aftermath of the end-Cretaceous mass extinction. In addition, the divergence of proxy variations from expected effects implies the Deccan eruption and Chicxulub impact could not have played a long-term role in governing the climatic and environmental perturbations following the Cretaceous-Paleogene Boundary.

Distribution of stable Н, О and С isotopes in natural waters in the area of the Taz oil and gas condensate field (Yamalo-Nenets autonomous region)

Relevance. The study of isotopic composition of water and dissolved substances makes it possible to determine not only their genesis, but also the fractionation processes occurring in the “water–rock–gas–organic matter” system over time, i. e. as different stages of the evolution of water composition pass through. Interest in the groundwater of the Arctic regions of Western Siberia is additionally associated with the widespread occurrence of oil deposits at the depths of formation waters and the possible influence of cryogenic metamorphization processes on composition of near-surface waters. Aim. To study and compare the isotopic composition of oxygen, hydrogen and carbon in natural waters of the Yamalo-Nenets autonomous region to identify conditional isotopic markers, as well as to be able to trace the evolution of the isotopic composition of waters along a vertical section in the area of the Taz oil and gas condensate field. Objects. Surface (river, soil and lake), underground waters of the active water exchange zone of the Yamalo-Nenets autonomous region and formation waters of oil and gas deposits of the Taz field. Methods. The study of the isotopic composition of oxygen, hydrogen, and carbon of water-dissolved carbon dioxide was carried out in the Research Equipment Sharing Center at the Institute of Geology and Mineralogy SB RAS using Isotope Ratio Mass Spectrometer FinniganTM MAT 253 equipped with H/Device and GasBench II for sample preparation. Results and conclusions. The paper introduces the data on isotopic composition of O, H and C for natural waters of the Yamalo-Nenets autonomous region. The authors have determined the characteristic trends in changes in the isotopic composition of water and dissolved carbon dioxide for various water bodies. Surface and underground waters with active water exchange in terms of isotopic composition (δD and δ18О) are infiltration. As water moves down the section, with an increase in the time of interaction of the “water–rock” system and increase in temperatures, the isotopic composition becomes significantly heavier with a slope from the GMWL to the right. The authors compiled the diagram of the evolution of water-dissolved carbon isotopic composition in the region according to the obtained and some literature data. Despite the wide range of δ13C values from –30.4 to 23.6 ‰, there are, obviously, only two sources of carbon dioxide in the region: biogenic and atmospheric, with biogenic being predominant for groundwater.

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.

The Bougrine Zn-Pb deposit, the largest salt diapir-related Mississippi Valley-type deposit in the Eastern Maghreb salt diapir province, Tunisia

The Bougrine Zn-Pb sulfide deposit (5.5 Mt @ 12 % Zn + 2.5 % Pb) in the Eastern Maghreb salt diapir province of Tunisia is located at the northeastern end of the Lorbeus-Bougrine diapir. The several-km large diapir is composed of Triassic evaporite that intruded about 10 km-thick Jurassic and Cretaceous marine sedimentary rocks during the Cretaceous and Tertiary. Mineralization occurs in breccia zones at the contact with the Triassic diapir and in the peridiapiric Cretaceous strata. Most of the ore is stratabound (F2 orebody) with microsphalerite disseminations in organic-rich laminated black limestone of the Cenomanian-Turonian Bahloul Formation, where sphalerite occurs as infill of Globigerina shells, as massive replacement of Globigerina-rich layers, as banded colloform sphalerite and in voids as euhedral, coarse-grained crystals together with skeletal galena and minor marcasite. Abundant degraded oil seepages in the orebodies and their host rocks testify to the existence of a (former) hydrocarbon reservoir.The various sphalerite generations have highly variable Mn and Fe contents; Cd has an average content of 445 ppm; As and Hg contents are in the 200 ppm range; Tl content is about 40 ppm; Ga content is about 10 ppm; and In content is consistently <1 ppm. Fluid inclusions in celestite, coarse-grained late-stage sphalerite and calcite indicate moderate fluid salinities (16 ± 2 wt% NaCl eq.) and moderate temperatures (85 to 146 °C). The empirical trace-element sphalerite geothermometer gives 184 ± 38 °C for the main-stage microsphalerite and the banded colloform sphalerite which have no measurable fluid inclusions.A wide range of δ13C (-13.6 to 5.6 ‰) and δ18O (-19.8 to 33 ‰) values is observed in ore-stage and post-ore calcite. Ore-stage calcite commonly has negative δ13C values reflecting involvement of carbon from organic matter; its δ18O composition with an average of 22.6 ± 2 ‰ (19.7 to 26.0 ‰) may be explained by a moderate-temperature hydrothermal fluid. There is no systematic δ34S variation between and across the different styles of mineralization. The range of δ34S of 6–19 ‰ with a mean of 13 ‰ is close to the δ34S value of local and regional Triassic marine sulfate (δ34S = 16 ‰). Thermochemical reduction of Triassic sulfate, likely mediated by hydrocarbons, is the most probable source for sulfur in the ores. Lead isotope data on galena are within a narrow field of upper crustal signature (206Pb/204Pb = 18.71–18.77; 207Pb/204Pb = 15.66–15.70; 208Pb/206Pb = 38.81–38.97) indicating a homogeneous ore fluid.The major characteristics of the Bougrine ore deposit are typical of Mississippi Valley type Pb-Zn deposits and indicate large-scale fluid circulation likely related to stacking and uplift in the northern Tunisian Nappes Zone during the Miocene. Both the hydraulic load of meteoric water and over-pressured basinal and basement fluids during compressional movements favored southward fluid migration along basement discontinuities and most permeable strata in the Mesozoic-Cenozoic sedimentary pile. Low-pressure domains around salt diapirs in a rifting environment allowed focused upward fluid flow, and the hydrocarbon reservoir of the Bahloul Formation then provided the geochemical trap for efficient base metal deposition.

Origins of the Ediacaran Doushantuo High-Grade Primary Phosphorites at Kaiyang, Guizhou Province, China.

The Ediacaran Doushantuo phosphate deposit in Kaiyang, Guizhou Province, China, contains thick phosphate ores. Most of the ores are reconstituted phosphorite, and there have been few studies of the primary phosphorites, which has led to controversy regarding the origins and nature of mineralization of these phosphate-rich deposits. We identified high-grade primary phosphorites in the Kaiyang area and undertook a stratigraphic, petrological, sedimentological, geochemical, and isotopic study of these rocks. Moving up-section, the Longshui phosphate ore deposit comprises granular, micritic, stromatolitic, honeycomb, and sandy phosphorites. The first four types of phosphorite contain abundant biological structures, such as spherical, lobe-like, and amorphous forms. These are mainly fossils of benthic multicellular red algae, along with other types of algae. These fossils comprise >70% of the phosphorites, indicating that these are protist phosphorites. The ores are massive, unstratified, and contain numerous layered cavity structures, indicating that the ore bed was originally a reef. The phosphorites have P2O5 contents of 38.6-40.2 wt %, with an average of 38.9 wt %. The Al2O3 + TiO2 values are 0.02-0.44 wt %. The δ18O values of the samples vary from 13.76 to 16.57‰, with an average of 14.60‰, and δ13C values range from -15.789 to -8.697‰, with an average of -13.133‰. The samples exhibit rare-earth element patterns that are enriched with middle rare-earth elements and have strongly negative Ce anomalies. The geochemical features show that the reef was deposited in clear and oxidized waters. The discovery of this high-grade protist phosphorite shows that the involvement of algae was key to the formation of the Kaiyang phosphate-rich deposit.

The gold mineral systems of the West Qinling orogen, central China: New insight from the Baguamiao gold deposit

The Baguamiao gold deposit is the first large deposit discovered in the West Qinling orogen in central China in the 1990 s. However, the occurrence of invisible gold in the deposit has not been reported. There is also no consensus on whether magmatic activity is involved in the gold mineralization, the style of mineralization, and the mechanism of gold precipitation. In this study, the in-situ trace elements, and chemical mapping of pyrite and pyrrhotite in the Baguamiao gold deposit were carried out for the first time. These data combined with the C-H-O isotope data of quartz, ankerite and calcite were used to determine mineralization process. In the Baguamiao gold deposit, five types of pyrite (Py0 to Py4) and pyrrhotite (Po0 to Po4) were identified, corresponding to the sedimentary-diagenetic period and four stages of mineralization (Stage I to Stage IV), respectively. From stage I to stage IV, gold mineralization in pyrite and pyrrhotite occurs as either visible or invisible crystals. The latter occurs dominantly as lattice-bound solid solutions (Au+) and is related to the content of Cu and Te. Co and Ni contents and Co/Ni ratios indicate that pyrite and pyrrhotite are magmatic-hydrothermal origin and affected by fluid-rock interaction. The change of Se and Te concentrations in pyrite and pyrrhotite indicates that oxygen fugacity (ƒO2) was increased from stage I to stage II, and then decreased during stage III and stage IV. In addition, the δ18O values of quartz, calculated δ18OH2O values of the ore-forming fluids and δ13C values range from 16.9 to 20.3 ‰, 7.7 to 12.9 ‰, and − 19.3 to + 0.2 ‰, respectively. Such isotopic signature records typical characteristics of orogenic gold deposit. The ore-forming fluid is a mixed hydrothermal solution involving metamorphic water, magmatic water, and meteoric water, and mixed with marine carbonate and sedimentary organic matter. Gold was precipitated by phase separation, fluid-rock interaction, and fluid mixing. Combined with the tectono-magmatic evolution, metamorphic deformation, and gold mineralization age of the West Qinling orogen, it can be concluded that with the closure of the Mianlue portions of the East Paleo-Tethys Ocean, the Baguamiao gold deposit was formed in the post-collisional extensional environment between the South China Block and the North China Block in the Late Triassic and is an orogenic gold deposit reference to the crustal continuum model.

Mineralogy and genesis of the Pb-Zn-Sb-Ag vein H32A in the Příbram uranium and base-metal district, Bohemian Massif, Czech Republic

A detailed paragenetic, electron microprobe, fluid inclusion and S,C,O-isotope study was conducted on Pb-Zn-Sb-Ag mineralization of the vein H32A, Háje deposit, Příbram uranium and base-metal district, Czech Republic. The vein is hosted by folded Neo-Proterozoic sandstones and siltstones of the Teplá-Barrandian unit in exo-contact of the Central Bohemian Plutonic Complex of the Variscan age (354–335 Ma). The ore zone is close to a crustal-scale tectonic zone dividing two distinctly different basement blocks of the Bohemian Massif. A rich mineral assemblage consisting of 44 mineral phases formed during two major mineralization stages (siderite-sulphidic and calcite-sulphidic) widespread in the Příbram area. A complex history of the vein is evidenced from the presence of seven mineralization sub-stages and widespread repeated metasomatic replacement and dissolution of older vein during younger mineralizing events. The vein is dominated by carbonates (especially siderite-rhodochrosite, less frequently dolomite-ankerite-kutnohorite, rarely calcite), minor constituents are quartz, illite-muscovite, and chamosite (locally with up to 1.52 apfu Sb, 0.53 apfu Zn and 0.38 apfu Pb). Ore minerals are dominated by Ag-poor galena. The Fe-poor sphalerite, pyrrhotite, löllingite, arsenopyrite, Pb-Sb, Pb-Sb-Ag and Cu-Ag-Sb sulphosalts are subordinate phases and dyscrasite, native antimony and native arsenic are accessories. The fluid inclusion study revealed the wide ranges of homogenization temperatures (210–<100 °C) and salinities (0.0–30.5 wt% NaCl eq.) of exclusively aqueous fluid inclusions. General decrease of both parameters occurred during evolution of the vein. Sulphur isotope disequilibrium was found between co-existing galenas and sphalerites. The calculated fluid δ13C values range between −9.0 and −12.3 ‰ V-PDB, implying for a well-mixed source of carbon, or its significant re-cycling during processes of dissolution-reprecipitation of vein carbonates. The calculated fluid δ18O values are highly positive for early siderite (+7.2 to +9.6 ‰ V-SMOW), and near-zero for later dolomites and calcites (−2.9 to +3.2 ‰ V-SMOW). The siderite fluids likely represent deeply circulated waters, which underwent a significant isotope exchange with hot crustal rocks. Late low-salinity fluids were likely sourced from the Permian partly evaporated freshwater piedmont basins. The high-salinity Ca-Na-Cl brines rarely recorded in secondary fluid inclusions hosted by late calcite likely represent either local “shield brines” or basinal brines of marine provenance. The study site covers a metallogenetically significant portion of the Late Variscan fluid history within an active crust-scale tectonic zone hosted by basement of the Bohemian Massif. A pronounced Ag enrichment of this vein is mainly caused by widespread occurrence of inclusions of late-stage Ag minerals (dyscrasite) in the vein, which form rich concentrations in the shallower parts of the Háje deposit.

The patchiness of soil 13C versus the uniformity of 15N distribution with geomorphic position provides evidence of erosion and accelerated organic matter turnover

Farming on hillslopes often affects the accumulation and loss of soil organic matter (SOM) depending on slope position and cropping patterns. Most hillslope studies focus on soil movement to characterize SOM turnover under erosive conditions. In this study, we trace erosion and characterize agronomic practices erosive impacts on SOM translocation and transformation along geomorphic positions. To achieve this, we assessed the horizontal distribution (upper 15 cm) and vertical distribution (to 100 cm profiles) of soil δ15N and δ13C isotope abundance individually. We mapped the spatial distribution of δ13C, δ15N, and SOM turnover indices as a novel approach to tracing erosion and degradation of SOM in the field. Except for tillage (conventional vs. reduced tillage), other individual agricultural practices (residue removal with no cover crop vs. retaining residuals, cover cropping, and fertilizer 0, 40, and 80 kg ha-1 nitrogen) caused no significant shifts in δ15N and δ13C values in topsoil (0–15 cm). Among the evaluated factors, topography and depth predicted soil δ15N and δ13C profiles. Trends in δ13C vs. δ15N showed a wider range of δ13C values in topsoil of upslope plots under reduced tillage, while in the depositional location, conventional tillage had the same effect. This suggests erosion under reduced tillage occurred. Erosion and accelerated decomposition gradually slowed δ13C enrichment with soil depth. Digital soil mapping approach depicted low continuity of δ13C vs. high continuity of δ15N with geomorphic position We attributed the intermediate δ13C values, and steeper slope of δ13C against logarithm of soil organic carbon (SOC) across the slope to erosion and high SOM turnover, particularly of recently added plant inputs. Current results support the prediction of intensive vs. conservation practices’ effects on upslope soil stability and the fate of SOM in both topsoil and at depth of sloping farmlands.

Reconstructing habitat use, identifying origin and discrimination of the barramundi (wild and farmed) populations using otolith stable isotope analysis

Barramundi or Asian seabass, Lates calcarifer (Bloch, 1790), is a euryhaline fish that is widely distributed in the Indo-West Pacific. This species is a commercially important fish which is extensively farmed in Taiwan. Currently, there is a lack of information on the origin, habitat use and migratory behavior of barramundi in Taiwanese waters. Here, δ13C and δ18O values of otolith growth time series were evaluated in barramundi (wild and farmed), and salinity was estimated from otolith δ18O values to report the habitat use and origin of wild individuals. Also, wild individuals and farmed individuals were discriminated using δ13C and δ18O values of otoliths to explore whether the individuals captured from Danshui River Estuary have aquaculture origin. The wild individuals collected from the Danshui River Estuary displayed a relatively wide range of δ13C and δ18O values however farmed samples showed a consistent change among the individuals within a group. Based on otolith δ18O values and estimated salinity, the most of wild fish samples were born in the brackish water environment. The estimated salinity experienced by the wild individuals also suggests that migration behavior varies among individuals. Moreover, some wild individuals showed a regular migration pattern but the range of salinity experienced by individuals varied greatly. By comparing the δ13C and δ18O values, it was found that significant differences existed among groups of fish and overall the correct classification accuracy was 95% using quadratic discriminant analysis. The δ13C and δ18O values of the otolith core revealed that only one sample caught in the Danshui River Estuary might have aquaculture origin. In this study, stable isotope (δ13C and δ18O) values were effectively applied to reconstruct the life history of barramundi and to distinguish individuals having a different origin. The results of this study can be used as a reference for sustainable management of this important fishery resource.

Facies and Origin of Tufa Deposits from the Gostilje River Basin and the Sopotnica River Basin (SW Serbia)

Tufa accumulations from the Gostilje River Basin and the Sopotnica River Basin in SW Serbia are represented by both active and fossil tufa precipitates. The aim of this study is to distinguish and describe different tufa facies and to determine the environmental conditions, based on stable isotope data. We also compare our analysis with other tufa deposits in Europe. Four facies are distinguished: moss tufa, algal tufa, stromatolitic laminated tufa, and phytoclastic tufa. The dominant constituent of all tufa samples is low Mg-calcite, whereas the presence of sylvite is noted in two samples from the Gostilje River Basin. The δ18O values range from −9.07‰ to −10.79‰ (mean value: −9.81‰), while the δ13C values range from −6.50‰ to −10.34‰ (mean values −9.01‰). The stable isotope values (δ13C and δ18O) indicate that these tufa deposits were precipitated from cold, ambient water supported by CO2 of an atmospheric origin. We emphasize that this is the first data about stable isotope analyses of tufa deposits from Serbia.

STABLE ISOTOPES (δ13C AND δ15N) ANALYSIS INDICATE RESOURCE PARTITIONING BY ELASMOBRANCHS FROM THE TROPICAL COASTAL WATERS OF KUALA PAHANG, MALAYSIA

Nearshore habitats support high levels of biodiversity and important ecological processes such as trophic dynamics. This study aims to determine the trophic dynamics of elasmobranchs and other marine species from the coastal waters of Kuala Pahang, using stable isotope analysis. Samples of invertebrates, teleosts, and juvenile elasmobranchs were collected at the coastal waters of Kuala Pahang, and the composition of stable isotopes δ13C and δ15N were determined. Of all species, teleosts had the narrowest range of δ13C values, of between -17.5‰ and -16.7‰, indicating their reliance on similar types of food resources. On the contrary, elasmobranchs had the widest range of food sources as indicated by the δ13C values, of between -26.8‰ and-16.8‰. The banded sicklefish (Drepane longimana) occupied the highest trophic level as indicated by a δ15N value of 12.4‰, whereas the red stingray (Hemitrygon akajei) had the lowest trophic level with a δ15N value of 4.9‰. The depleted δ13C values indicated resource partitioning among elasmobranchs, presumably due to the utilisation on estuarine-based carbon resources. This study highlights the potential importance of the estuary of Kuala Pahang as a feeding ground for juvenile elasmobranchs.

Reconstruction of landscape and climate of the largest drainage basin in the Ladakh Range, NW Trans Himalaya during the last 7000 years

Landform geomorphology and glacial lake deposits in the largest drainage basin of the Ladakh Range i.e. Chang La-Tangtse basin were studied to infer their palaeoclimatic significance. The grain size, mineral magnetism, percentage loss on ignition (%LOI) and organic carbon stable isotope (δ13C) data in combination with total organic carbon (TOC) supported by AMS 14C (calibrated) dates of a 190 cm long section from the Chang La-Tsoltak palaeolake provides a climatic record since the last ∼ 7075 cal yr BP. The χlf, χARM, and SIRM values suggest that the catchment-derived palaeolake sediments predominantly contain magnetically “soft” minerals like magnetite and maghemite. The δ13C values range between −21 and −24 ‰ with an average of –22 ‰ which suggests a mixed C3-C4 plant signature and water stressed ecosystem. The relatively small variations in the δ13C values of organic matter in the entire lake profile suggest a stable climatic condition. The prominent effect of westerlies is seen between 7075 and 6040 cal yr BP with huge detrital influx at the lake bottom indicating a glacial advancement in the region. The affect of Mid-Holocene warm period is evident at 6040 cal yr BP with the advent of ISM. Paradigm shifts in the proxy values are observed at 5710, 4890, 3435, and 2800 cal yr BP. The influence of westerlies gradually reduces at 2800 cal yr BP. The landscape evolution and the climatic variations in the Trans-Himalaya are primarily governed by westerlies and do not correspond to the Indian monsoon variability records, particularly during the Mid-Holocene Thermal Maxima. Several other regions of the Ladakh Range also record similar climatic variations, indicating that the palaeolake sediments also reflect regional climate variations.

δ26Mg-δ13C-δ18O systems as geochemical tracers for dolomite recrystallization: A case study of lower Ordovician dolomite from Tarim Basin

Widespread replacement dolomite occurs commonly in the geologic record. These dolomites are generally characterized by different crystal sizes and shapes that have at times been interpreted to represent multistage dolomitization; although the variation of dolomite texture could also have resulted from the recrystallization of precursor dolomite. It is important, but challenging, to differentiate these two scenarios to better understand the nature of dolomite and the associated processes of dolomitization. Our study explores this problem by using δ26Mg, δ13C, and δ18O isotopes to characterize the different crystal morphologies exhibited by Ordovician dolomites from the Tarim Basin, China.Although the dolomites show distinct textures and crystal morphologies, there are no discernible trends in their δ26Mg values (from −1.66 to −2.39‰), suggesting that these dolomites were formed by the same dolomitizing fluid. This interpretation is supported by an overlapping range of δ13C values (from 0.46 to −1.89‰). By contrast, the δ18O data demonstrate a wide range of values, from −3.8‰ to −8.8‰, reflecting the different degree of recrystallization with increasing burial temperatures. We suggest that the Mg and C isotopes remained unchanged during recrystallization because Mg and C were rock-buffered, so the recrystallized dolomite inherited Mg and C from the precursor dolomite. Based on these results, it appears that Mg isotopes, together with conventional OC isotopes, can provide a diagenetically robust geochemical tracer for identifying dolomite recrystallization in the geological record.