Stable Isotope Investigations Research Articles

Ediacara biota flourished in oligotrophic and bacterially dominated marine environments across Baltica

Middle-to-late Ediacaran (575–541 Ma) marine sedimentary rocks record the first appearance of macroscopic, multicellular body fossils, yet little is known about the environments and food sources that sustained this enigmatic fauna. Here, we perform a lipid biomarker and stable isotope (δ15Ntotal and δ13CTOC) investigation of exceptionally immature late Ediacaran strata (<560 Ma) from multiple locations across Baltica. Our results show that the biomarker assemblages encompass an exceptionally wide range of hopane/sterane ratios (1.6–119), which is a broad measure of bacterial/eukaryotic source organism inputs. These include some unusually high hopane/sterane ratios (22–119), particularly during the peak in diversity and abundance of the Ediacara biota. A high contribution of bacteria to the overall low productivity may have bolstered a microbial loop, locally sustaining dissolved organic matter as an important organic nutrient. These oligotrophic, shallow-marine conditions extended over hundreds of kilometers across Baltica and persisted for more than 10 million years.

Using stable isotopes and functional weed ecology to explore social differences in early urban contexts: The case of Lattara in mediterranean France

Integrated stable isotope investigation of plant and animal ecology can shed new light on the practicalities and politics of land management. Ecological analysis of archaeobotanical weed flora offers a complementary approach to arable growing conditions. Here we introduce the first combined study of stable isotope compositions (carbon and nitrogen) of plant and faunal remains and functional weed ecology from mediterranean France in order to investigate agricultural strategies under urbanisation and their social implications. Animal bones and charred crops and weeds are investigated from two archaeologically distinct residential areas from 5th century BCE Lattara, zones 1 and 27, during a period characterised by significant urban expansion in the region. Plant carbon and nitrogen isotope composition and functional weed ecology suggest some differences in growing conditions between crops found in the two zones, zone 27 being associated with more intensively cultivated crops than zone 1, where extensive cultivation, which can achieve much greater surplus, was dominant. These findings coincide with archaeological evidence of a ‘richer’ variety of material culture and foodstuffs in zone 1. Carbon and nitrogen isotopic values of animal bone collagen suggest that the main domesticates from both zones consumed a similar diet; however, rabbits exhibit a difference, with those from zone 1 having significantly higher δ15N, implying that the two zones sourced this species differently.

Diet, sex, and social status in the Late Avar period: stable isotope investigations at Nu\u0161tar cemetery, Croatia

Diet often plays a vital role in defining social divisions within and between social groups and thus can be used to understand the social paradigms of archeological cultures. During the Early Avar period (568–630 A.D.), burial evidence indicates that there were strong demarcations of social stratification and divisions between sexes and age groups; however, the symbols of intra-population heterogeneity become increasingly rare during the Late Avar period (680–822 A.D.). In this study, we investigate social differences expressed through diet in the cemetery population from Nuštar, eastern Croatia (eighth to early ninth century), to determine whether dietary social disparities existed during the Late Avar period in this region. Stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) from bone and dentine collagen shows no dietary differences, neither between high, middle, and low status individuals, nor between males, females, and juveniles. These results likely reflect the outcome of the social homogenization process that began after the failed Avar attack on Constantinople in 626 A.D. Geographical patterning is visible when the data from Nuštar is compared to data from other Middle and Late Avar sites. While Avar sites in the southern and south-eastern frontiers of the Avar qaganate do not display dietary differences between sexes, previous isotopic work on populations in Lower Austria shows that males consumed a higher proportion of animal protein than females. This is likely the result of Frankish influence and reflects diversity in social practices within the Avar qaganate itself during the Middle and Late Avar periods.

Mixed Livelihood Society in Iin Hamina – a Case Study of Medieval Diet in the Northern Ostrobothnia, Finland

ABSTRACTA stable isotope investigation of a large Medieval population buried in Iin Hamina, northern Finland, has been used to reconstruct palaeodiet. Iin Hamina is situated approximately 30 km away from the modern city Oulu, in close proximity to the Bothnian Bay coast and the river Ii. The material used in this study is human skeletal material from an Iin Hamina cemetery dated as 15 to 17th centuries AD and animal bones excavated in Northern Ostrobothnia from pre-industrial contexts. Stable isotope analysis of well-preserved collagen indicate that both freshwater and marine fish was the dominant protein source for the people buried at the Iin Hamina cemetery.

“To ‘seafood’ or not to ‘seafood’?” An isotopic perspective on dietary preferences at the Mesolithic-Neolithic transition in the Western Mediterranean

Stable isotope investigations of the Prehistory of the Western Mediterranean have increased exponentially during the last decade. This region has a high number of Mesolithic and Neolithic carbon and nitrogen isotope ratio data available compared with other world areas, resulting from the interest in the “transition” between hunter-gathering and farming. This type of analysis is important as one of the few tools that give direct information on the poorly understood dietary transition from hunter-gatherer to agro-pastoralist subsistence in the Mediterranean Basin. Carbon and nitrogen stable isotope analysis on bulk collagen are especially useful for exploring marine vs. terrestrial protein input and therefore assess marine resource exploitation by these two different lifestyles. Gathering together all isotopic data for these chronologies we show that the Western Mediterranean underwent a unique/distinct Neolithisation process. These data show a gradual dietary shift in aquatic resource consumption during the transition to farming that contrasts to elsewhere in Europe.

Biologically mediated crystallization of buddingtonite in the Paleoproterozoic: Organic-igneous interactions from the Volyn pegmatite, Ukraine

The Volyn pegmatites from Volodarsk-Volynskyi in the Zhytomyr Oblast, NW Ukraine, are associated with granites genetically related to the Paleoproterozoic Korosten pluton. Their late-stage evolution is characterized by the formation of opal-cemented breccia. A polymineralic pseudomorph after beryl within the breccia includes bertrandite (±euclase) + F-muscovite (with tobelite component) + buddingtonite + organic matter (OM) + opal (+ traces of K-feldspar, albite, columbite, FeS 2 , barite, REE-minerals). Sector-zoned and platy to fibrous buddingtonite has variable (K+Na)- vs. NH 4 -contents (electron microprobe analyses) and some H 2 O or H 3 O + , as indicated by microscope infrared spectroscopy. We suggest that ammonium was produced by decay of OM, which is partly preserved in the pseudomorph. Energy-dispersive electron microprobe data of the OM show with increasing O–decreasing C-N-content due to degassing; the OM contains the high field strength elements Zr (≤7 at%), Y (≤3 at%), Sc (≤0.8 at%), REE (≤0.3 at%), Th (≤0.2 at%), and U (≤1.25 at%), which increase with increasing O-content. Transmission electron microscopy of the OM confirms the presence of N; Zr, Si, and O (with other HFSE) are concentrated in nanometer-sized areas and at the transition from OM to opal in nanometer-sized platy Zr-Si-O crystals. C-rich areas are amorphous but show poorly developed lattice fringes. OM is present in the pseudomorph also as brown pigmentation of opal and in pegmatitic beryl from Volyn as a component in late stage fluid inclusions, identified by C-H vibrational bands in infrared spectra. Stable isotope investigations of C and N of buddingtonite, black opal and kerite (fibrous OM known from the literature to occur in the Volyn pegmatites and interpreted as microfossils) indicate a biogenic origin of the OM. We propose that OM in the pseudomorph is condensed kerite, which achieved the high concentrations of high field strength elements via fluid-pegmatite interaction. Although no age determination of minerals in the pseudomorph is available, textural arguments and phase equilibria indicate its formation in a late stage of the pegmatite evolution, at P-T conditions below ~100 MPa/150 °C. We favor a conceptual model for the formation of the Volyn buddingtonite in analogy to Phanerozoic occurrences of buddingtonite, where over and around the shallow anorthosite-granite Korosten pluton hydrothermal convection cells introduced N-bearing hydrocarbons and its precursors into the cooling igneous rocks. Due to the elevated temperature, the OM disintegrated into degassing volatile and non-volatile residual components analogous to petroleum maturation. Organic N, released as NH 4 , was then incorporated into buddingtonite.

Hydrochemical and stable isotopic investigation of groundwater quality and its sustainability for irrigation in the Hammamet-Nabeul basin, northeastern Tunisia

The major ion hydrochemistry, sodium absorption ratio (SAR), sodium percentage, and isotopic signatures of Hammamet-Nabeul groundwaters were used to identify the processes that control the mineralization, irrigation suitability, and origin of different water bodies. This investigation highlights that groundwater mineralization is mainly influenced by water-rock interaction and pollution by the return flow of irrigation water. The comparison of groundwater quality with irrigation suitability standards proves that most parts of groundwater are unacceptable for irrigation and this long-term practice may result in a significant increase of the salinity and alkalinity in the soils. Based on isotopic signatures, the shallow aquifer groundwater samples were classified into (i) waters with depleted δ18O and δ2H contents, highlighting recharge by modern precipitation, and (ii) waters with enriched stable isotope contents, reflecting the significance of recharge by contaminated water derived from the return flow of evaporated irrigation waters. The deep-aquifer groundwater samples were also classified into (i) waters with relatively enriched isotope contents derived from modern recharge and mixed with shallow-aquifer groundwater and (ii) waters with depleted stable isotope contents reflecting a paleoclimatic origin. Tritium data permit to identify three origins of recharge, i.e., contemporaneous, post-nuclear, and pre-nuclear. Carbon-14 activities demonstrate the existence of old paleoclimatic recharge related to the Holocene and Late Pleistocene humid periods.

Mate similarity in foraging Kerguelen shags: a combined bio-logging and stable isotope investigation

Similarity or dissimilarity between 2 individuals that have formed a pair to breed can occur in morphology, behaviour and diet. Such patterns influence partners’ cooperation when rearing their offspring, consequently influencing reproductive success. They may confer different benefits, depending on species and contexts. However, the extent to which breeding partners are more similar in morphology, behaviour, and diet is poorly documented. Furthermore, the relationship between behavioural consistency and mate choice is particularly poorly understood. To investigate these issues, Kerguelen shags Phalacrocorax verrucosus, which are monogamous with high mate fidelity across years, were studied. Partners were equipped with GPS and diving behaviour loggers. Feather and blood samples were analysed for stable isotopes (δ13C, a proxy of foraging habitat, and δ15N, a proxy of diet/trophic position). Generalized linear mixed effects models and permutation tests were used to investigate pair similarity in morphology, foraging behaviour, behavioural consistency, overlap in foraging areas, and diets/foraging habitats. Mates were found not to exhibit size-assortative mating, but were more similar in foraging behaviour. They did not show assortative or disassortative mating based on foraging behavioural consistency. Furthermore, they followed more similar bearings and overlapped more in foraging areas. In accordance with this, partners were more similar in δ15N. Given the lack of assortative mating by morphology, the similarity in behaviour could be due to individuals selecting mates with similar foraging abilities, linked with individual quality, and/or subsequently using information gained from their partners’ foraging strategies (e.g. local enhancement). This could help breeding pairs increase their foraging efficiency and reproductive success.

Whole rock geochemistry, molybdenite Re-Os geochronology, stable isotope and fluid inclusion investigations of the Siah-Kamar deposit, western Alborz-Azarbayjan: New constrains on the porphyry Mo deposit in Iran

The Siah-Kamar porphyry Mo deposit, located in the western Alborz-Azarbayjan magmatic belt, is the first and largest Mo deposit in the Iran. This deposit is mainly hosted by an I-type, shoshonitic quartz monzonite to monzonite intrusion and also extends in the surrounding lower to middle Eocene volcanic rocks. The geochemical features of the Siah-Kamar intrusion show enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE), and significant negative anomalies of Nb, Ta and Ti analogues to the magmas derived from metasomatized sub-continental mantle. Porphyry molybdenum mineralization is associated with potassic, sericitic, argillic, and propylitic alteration zones. Mineralization occurs in disseminated form, in veins/veinlets and in hydrothermal breccias. The main ore minerals comprise molybdenite, chalcopyrite and bornite. The Microthermometric analyses at Siah-Kamar deposit showed that the halite-bearing inclusions contain high salinity (30.9–60.7wt% NaCl eq.) with homogenization temperature ranging from 226°C to 397°C. The homogenization temperature of two phase liquid-rich inclusions range between 224°C and 375°C. The salinity of this type inclusions range from 0.6 to 7.5wt% NaCl equivalent. The two-phase vapor-rich fluid inclusions homogenized at 270°C to 397°C. The salinity of this type fluid inclusions lie within the range of 0.6 to 4.24wt% NaCl equivalent. Coexisting two phase V-rich and L-rich fluid inclusions in quartz associated with molybdenite provide evidence for boiling at 270°C to 400°C. The δ18Owater values of quartz in the molybdenite-bearing veins vary from +2.16 to +4.05‰, suggesting a magmatic origin for the ore-forming fluids. Re-Os isotopic dating of molybdenite indicated a mineralization age of 41.9±3.6Ma. The Re concentration in molybdenite suggests incorporation of mantle derived melt with crustal materials. The late Eocene magmatism along the western Alborz-Azarbayjan magmatic zone resulted from the Neo-Tethys subduction beneath the Iranian plateau. The Siah-Kamar monzonitic intrusion hosting the Mo deposit, could be considered asan example among the late Eocene intrusions within the western Alborz-Azarbayjan magmatic zone for any further exploration in this zone.

Low trophic level diet of juvenile southern elephant seals Mirounga leonina from Marion Island: a stable isotope investigation using vibrissal regrowths

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 577:237-250 (2017) - DOI: https://doi.org/10.3354/meps12240 Low trophic level diet of juvenile southern elephant seals Mirounga leonina from Marion Island: a stable isotope investigation using vibrissal regrowths Nico Lübcker1,*, Ryan R. Reisinger1,4, W. Chris Oosthuizen1, P. J. Nico de Bruyn1, André van Tonder1, Pierre A. Pistorius2,3, Marthán N. Bester1 1Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield 0028, Pretoria, South Africa 2Marine Apex Predator Research Unit, Institute for Coastal and Marine Research, Nelson Mandela Metropolitan University, South Campus, Port Elizabeth 6031, South Africa 3DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology, Nelson Mandela Metropolitan University, South Campus, Port Elizabeth 6031, South Africa 4Present address: Centre d’Etudes Biologiques de Chizé, UMR 7372 du CNRS-Université de La Rochelle, 79360 Villiers-en-Bois, France *Corresponding author: nlubcker@zoology.up.ac.za ABSTRACT: Insight into the trophic ecology of marine predators is vital for understanding their ecosystem role and predicting their responses to environmental change. Juvenile southern elephant seals (SES) Mirounga leonina are considered generalist predators within the Southern Ocean. Although mesopelagic fish and squid dominate their stomach lavage samples, the stable isotope profile captured along the length of sampled vibrissae of young SES at Macquarie Island, southwest Pacific Ocean (54.5°S, 158.9°E) recently emphasized the contribution of crustaceans to their diet (likely Euphausia superba). Herein, we used the stable isotope values of sampled vibrissal regrowths with known growth histories to assess the diet of juvenile SES at Marion Island, southern Indian Ocean (46.8°S, 37.8°E) on a temporally integrated basis. We specifically aimed to quantify the possible contribution of crustaceans to the diet of juvenile SES. Sequentially (chronologically) sampled vibrissal regrowths of 14 juvenile SES produced fine-scale dietary information spanning up to 9 mo. The depleted stable isotope signatures of nitrogen (δ15N) (8.5 ± 0.6‰) and carbon (δ13C) (-20.3 ± 0.1‰) measured during the period of independent foraging suggested the use of a lower trophic level diet within the Polar Frontal Zone. A mixing model predicted that up to 76% of juvenile SES diet comprised crustaceans, consisting of 2 crustacean groups, each contributing 26% (credible interval, CI: 13-39%) and 50% (CI: 35-64%) to their diets, presumably representing subantarctic krill species. This first utilisation of the isotopic signature captured along the length of vibrissal regrowths confirms the inclusion and importance of crustaceans in the diet of juvenile SES. KEY WORDS: Crustaceans · Diet · Marine mammals · Pinnipeds · Stable isotopes · Vibrissae · Whiskers Full text in pdf format Supplementary material PreviousNextCite this article as: Lübcker N, Reisinger RR, Oosthuizen WC, de Bruyn PJN, van Tonder A, Pistorius PA, Bester MN (2017) Low trophic level diet of juvenile southern elephant seals Mirounga leonina from Marion Island: a stable isotope investigation using vibrissal regrowths. Mar Ecol Prog Ser 577:237-250. https://doi.org/10.3354/meps12240 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 577. Online publication date: August 18, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Stable isotope investigation of the migratory behavior of silver-haired bats (Lasionycteris noctivagans) in eastern North America

Stable isotope investigation of the migratory behavior of silver-haired bats (Lasionycteris noctivagans) in eastern North America

Lignite deposits of the Kutch Basin, western India: Carbon isotopic and palynological signatures of the early Eocene hyperthermal event ETM2

This study presents new results of combined palynological and stable carbon isotope (δ13C) investigations carried out in the well known lignite sequence at Panandhro, District Kutch, in the Gujarat state of western India. Dinoflagellate cysts and associated spore-pollen assemblage assign an early Eocene (Ypresian) age to the lignitic succession at Panandhro. Furthermore, a pronounced negative Carbon Isotope Excursion (CIE) of about 2.7‰, correlated to the Second Eocene Thermal Maximum (53.7Ma), a globally recognized hyperthermal event, was discovered in the middle part of the succession, consistent with the palynological constraints. This is the first record of an Eocene hyperthermal event (ETM2) from the Kutch Basin. Our data has regional implications for the age of the lignitic sequences across western India as it demonstrates that there is no significant age difference between the lignite deposits of the Kutch and Cambay basins. Our results also support a Lutetian age for the previously described vertebrate fossils, including whales, from the Panandhro mine section.

Diagenetic alteration of benthic foraminifera from a methane seep site on Vestnesa Ridge (NW Svalbard)

Anomalously low δ13C values in foraminiferal calcite tests are due to diagenetic alteration in methane seep sites. Our study applies diagenetically altered fossil benthic foraminiferal tests as geochemical tracers in reconstructing natural past methane seepage episodes at Vestnesa Ridge offshore NW Svalbard. We combine examinations of the test wall microstructure, mineralogical and stable carbon isotope composition of foraminifera and co-occurring authigenic carbonate nodules. We present a classification of visual and mineralogical characteristics of the exterior and interior test wall microstructure of the benthic foraminiferal species Cassidulina neoteretis having experienced different degrees of diagenetic alteration during methane seepage. Carbonate nodules comprising high-Mg calcite cement with 13–15mol% MgCO3 have δ13C values as low as −32.3‰, which is consistent with a methane-derived origin. The visual, mineralogical and stable isotope investigations of C. neoteretis indicate a variable degree of diagenetic alteration and show δ13C values between −0.6 and −16.9‰. The negative δ13C values in benthic foraminifera are largely caused by precipitation of isotopically light methane-derived authigenic carbonate as high-Mg-calcite coatings, whose relative contribution to the bulk foraminiferal carbonate is estimated to be up to 58wt%. Another key finding is the identification of the first seepage episode concurrent with Heinrich Event 1 (HE 1), and a second seepage episode at the onset of the Bølling-Allerød Interstadial.

Skuas (Stercorarius spp.) moult body feathers during both the breeding and inter‐breeding periods: implications for stable isotope investigations in seabirds

Seabirds are mostly thought to moult during the inter‐breeding period and the isotopic values of their feathers are often therefore assumed to relate to their assimilated diet during such periods. We observed Brown Skuas Stercorarius antarcticus lonnbergi and South Polar Skuas Stercorarius maccormicki moulting on a breeding site at King George Island, Antarctica. This raises concerns about the reliability of using stable isotopes in feathers to infer feeding localities of birds during the inter‐breeding period. We analysed the δ13C and δ15N values of growing and fully grown body feathers collected from the same individuals. For both species, δ13C values of growing feathers indicated feeding areas in the Antarctic zone (breeding grounds), whereas most fully grown feathers (100% for South Polar Skuas and 93.3% for Brown Skuas) could be assigned to northern latitudes (non‐breeding grounds). However, a few fully grown body feathers of Brown Skuas (6.7% of the feathers, belonging to two birds) showed isotopic values that indicated moult in the Antarctic zone. As the growth period of those feathers was unknown, they could not be used with confidence to depict the foraging behaviour of the birds during the non‐breeding period. Although precautions must be taken when inferring dietary information from feathers in seabirds where the moulting pattern is unknown, this study shows that if the development stage of a feather (growing/fully grown) is identified, then dietary information from both breeding and non‐breeding seasons can be obtained on the same individual birds.

Geochemical characterization of source rocks and oils from northern Iraq: Insights from biomarker and stable carbon isotope investigations

The origin of oil in the Cretaceous–Tertiary reservoirs of northern Iraq remains controversial. Consequently, a detailed geochemical study, including Rock-Eval pyrolysis, gas chromatography–mass spectrometry, and carbon isotope analysis was conducted on 65 source rock core and cuttings samples from the Najmah, Chia Gara, and Balambo formations, northern Iraq. Twenty-four crude oils were also analyzed to provide new insights into source organic matter, depositional environment, and correlations between crude oils and their probable source rocks.Bulk geochemical analysis of candidate source rock samples indicates that the Najmah Formation has more petroleum potential than the Chia Gara and Balambo formations. These three candidate source rocks were deposited in slightly different environments and have different organic matter types as determined by screening analysis and biomarker data. The Najmah Formation contains organic-rich (TOC up to 4.2 wt%) oil-prone type I-II kerogen deposited under anoxic conditions. The Chia Gara and Balambo formations contain mixed type II-III and type-III kerogens, oil- and gas-prone, deposited under less reducing conditions with more terrigenous organic matter input. Unfortunately, most of the rock samples contain less than 2.5 wt% TOC, which likely excludes them as source rocks, but more deeply buried equivalents may contain more organic matter.Biomarker and stable carbon isotope compositions suggest that Cretaceous- and Miocene-reservoired oils from the northern Iraq basins, although predominantly derived from marine carbonate organic matter, constitute five genetically distinct oil families. Based on age-specific biomarkers, the oils were probably derived from three active petroleum systems in northern Iraq: Jurassic, Jurassic–Early Cretaceous, and Early to mid-Cretaceous. Biomarker maturity parameters indicate that most of the oils were generated in the early oil window, similar to the extracts.

Stable isotope and multi-analytical investigation of Monte da Cegonha: A Late Antiquity population in southern Portugal

This study presents for the first time the diet of a Late Antiquity population in southern Portugal (Civitas of Pax Julia), from the Roman villa of Monte da Cegonha (predominantly 7th century CE). Stable isotope analysis (δ13C, δ15N, δ18O, 87Sr/86Sr) of human and faunal bone collagen and apatite was conducted in order to understand the influence of Roman subsistence strategies on the way of life of rural inhabitants of the area of Pax Julia and to explore their diet (types of ingested plants, amount of animal resources, terrestrial versus marine resources).X-ray diffraction (XRD) and Fourier transform infra-red spectroscopy (FTIR) analyses were used to determine the degree of bone diagenesis and assess the reliability of the bone stable isotopic composition for palaeodietary reconstruction. Anthropological analysis revealed a cariogenic diet, rich in starchy food and carbohydrates, in at least in two individuals based on the frequency of dental caries. Collagen and apatite carbon isotopic analysis suggested that C3 plants were the basis of the population's diet, complemented with some terrestrial meat and its by-products as reflected by the observed bone collagen nitrogen isotopic composition. Moreover, whilst the fairly low apatite-collagen spacing recorded in some skeletons (at around 4‰) may have been due to freshwater organisms intake, the relatively low nitrogen values observed indicate that this consumption did not occur very often, unless in the form of fresh fish of low trophic level or fish sauces. There were no significant differences in isotopic values depending on gender or burial type.Strontium and oxygen isotopic composition of bone apatite revealed a sedentary community, with the exception of a male individual who probably did not spend his childhood in Monte da Cegonha.

Fringes of the empire: Diet and cultural change at the Roman to post-Roman transition in NW Iberia.

A growing number of paleodiet investigations over recent years have begun to reveal the stark dietary differences that existed between regions of the Roman Empire, as well as significant changes in subsistence strategies after its fall. The present study explores the dietary changes at the Roman to post-Roman (Germanic) transition in the Northwest Iberian Peninsula, in order to improve our understanding of the changes that occurred at end of the Roman Empire in different regions across Europe and to also consider the influence of climate had on them. The carbon and nitrogen stable isotope investigation in bone collagen from A Lanzada, NW Spain (100-700 AD), which was an important commercial, coastal settlement has been presented. A human sample of 59 individuals, 6 of them subadults, is compared with 31 faunal specimens, which include a number of marine fish. Isotope data for the terrestrial fauna reveal the influence of the sea on the local isotope baseline. Analysis of the human samples indicates a mixed marine-terrestrial diet. A shift in mean human δ(13) C values from -16.7‰ to -14.3‰ provides clear evidence for a significant change in diet in the post-Roman period, probably through the intensification of both marine resources exploitation and C4 -plant consumption (presumably millet). A deterioration of paleoenvironmental conditions, together with a poor socioeconomic situation and the arrival of new people, the Sueves, who brought a new political and socioeconomic system have been discussed as the main causes for the dietary modification in post-Roman times.

Titanium stable isotope investigation of magmatic processes on the Earth and Moon

We present titanium stable isotope measurements of terrestrial magmatic samples and lunar mare basalts with the aims of constraining the composition of the lunar and terrestrial mantles and evaluating the potential of Ti stable isotopes for understanding magmatic processes. Relative to the OL–Ti isotope standard, the δ49Ti values of terrestrial samples vary from −0.05 to +0.55‰, whereas those of lunar mare basalts vary from −0.01 to +0.03‰ (the precisions of the double spike Ti isotope measurements are ca. ±0.02‰ at 95% confidence). The Ti stable isotope compositions of differentiated terrestrial magmas define a well-defined positive correlation with SiO2 content, which appears to result from the fractional crystallisation of Ti-bearing oxides with an inferred isotope fractionation factor of ΔTioxide–melt49=−0.23‰×106/T2. Primitive terrestrial basalts show no resolvable Ti isotope variations and display similar values to mantle-derived samples (peridotite and serpentinites), indicating that partial melting does not fractionate Ti stable isotopes and that the Earth's mantle has a homogeneous δ49Ti composition of +0.005 ± 0.005 (95% c.i., n=29). Eclogites also display similar Ti stable isotope compositions, suggesting that Ti is immobile during dehydration of subducted oceanic lithosphere. Lunar basalts have variable δ49Ti values; low-Ti mare basalts have δ49Ti values similar to that of the bulk silicate Earth (BSE) while high-Ti lunar basalts display small enrichment in the heavy Ti isotopes. This is best interpreted in terms of source heterogeneity resulting from Ti stable isotope fractionation associated with ilmenite–melt equilibrium during the generation of the mantle source of high-Ti lunar mare basalts. The similarity in δ49Ti between terrestrial samples and low-Ti lunar basalts provides strong evidence that the Earth and Moon have identical stable Ti isotope compositions.

Effects of wildfire on runoff generating processes in northern Mongolia

Seasonal runoff generation in a headwater (~100 km2) of the mountainous Sugnugr Basin, situated within the discontinuous permafrost zone of northern Mongolia, was investigated. The role of the active layer and the effects of a recent wildfire on runoff generation were elucidated. On the catchment scale, stormflow events were investigated by streamflow hydrograph analysis and stable isotope investigations. Hydrological response parameters indicate increasing recession periods and delayed flow fractions during summer as active layer thickness increases. Isotopic signature revealed a high ratio of meltwater in river baseflow in early summer and a gradual decline until the beginning of September. During a stormflow event in early summer, a high fraction of event water was determined by two-component hydrograph separation. At a taiga-vegetated hillslope, subsurface flow was observed following precipitation events after a relative increase in upper soil volumetric water content (VWC i ) of 0.05 m3 m−3, demonstrating the retarding characteristics of the organic surface layer. Depending on active layer depth, subsurface flow predominantly occurred in the organic surface layer in early summer and subsequently subsided into the underlying mineral layer as soils thawed. After a wildfire, the water retention capacity of the organic surface layer diminished, as was reflected by a VWC i of 0.01 m3 m−3. Here, stormflow water temperatures indicated quickflow in the mineral layer above a degenerated frost table. The results of the study suggest that wildfires increase stormflow runoff while baseflow declines. Hence, the problem of water shortages in downstream areas during dry weather conditions is exacerbated.

Cattle and sheep raising and millet growing in the Longshan age in central China: Stable isotope investigation at the Xinzhai site

Abstract Previous bone collagen stable isotope analyses conducted on faunal remains from archaeological sites from the Late Neolithic (Longshan) to the Bronze Age (Xia dynasty) in the Central Plains of China have revealed that C4 plants – most probably cultivated millets – constituted a major part of cattle fodder and also contributed to sheep diet, although to a lower extent. In the present study, this difference between cattle and sheep diet management was investigated at the Xinzhai site (occupation phases 2 and 3, ca. 1800–1705 cal. BC), focusing on the seasonal scale through sequential δ13C and δ18O analysis in tooth enamel. This primary objective related to the reconstruction of Bronze Age husbandry practices required an effort in interpreting δ18O sequences recovered from cattle and sheep molars: potential difficulty in the identification of the seasonal cycle could rise, inherent to a specific climatic regime. This region of China is nowadays under the influence of the East-Asian summer monsoon, whose strength undergoes variability on the annual scale, but also did in the past on decadal to century scales. At Xinzhai, all sheep teeth and one deer tooth delivered δ18O sequences comparable to previously published sequences from locations were rainfall δ18O is temperature controlled (no monsoon influence), revealing minimal influence of the summer monsoon over these animals' lifetime. Some cattle teeth delivered sequences with bimodal distribution of δ18O values on the annual scale, potentially reflecting the influence of a summer monsoon. Such variability among domestic stock could relate to interannual/interdecadal variability in the monsoon intensity at the site location, or to differences in herding practices between sheep and cattle. Concomitant analysis of δ13C values in deer molars confirmed a surrounding wild environment dominated by C3 plants throughout the year, supporting the idea that a C4 signal in cattle and sheep diets resulted from feeding practices involving cultivated millets. Furthermore, sheep had access to millet in late summer time while cattle were constantly foddered throughout the year, to a very high extent. Given the annual growth cycle of millet, with late summer maturity, a year round provisioning to cattle would suppose constitution of fodder. Constant provisioning could also have required cattle to be kept by the settlement all year round, inducing less investment in cattle herding, but in return, a necessarily important input to sustain cattle diet requirements at the daily scale. This could in fine be connected to the privileged status for cattle in social or ritual related activities at Xinzhai.