Stable Isotope Geochemistry

Isotope signals derived from molluscan shell carbonates allow researchers to investigate palaeoenvironments and the timing and periodicity of depositional events. However, it cannot be assumed that all molluscan taxa provide equally useful data owing to species-specific biological and ecological traits. The Mud Shell, Geloina erosa (Lightfoot, 1786) (syn. Polymesoda coaxans, syn. Polymesoda erosa), an infaunal mangrove bivalve, is a common component of archaeological deposits along Australia's tropical north coast and throughout the Indo-West Pacific. The ubiquity of G. erosa has led to numerous researchers incorporating this taxon into interpretations of associated deposits, particularly in the generation of radiocarbon chronologies and as a palaeoenvironmental proxy. Despite this, concerns have been expressed regarding the impact of G. erosa physiology and ecology on associated geochemical signals. Adaptations allowing the survival of this species within its highly changeable mangrove environment may introduce complexities into radiocarbon and environmental data archived within its shell. This study combines local environmental and hydrological data with isotopic analysis (δ 18 O, δ 13 C, and 14 C) of live-collected specimens to explore the interpretability of geochemical proxies derived from G. erosa. Results suggest a number of factors may impact geochemical markers in unpredictable ways, eroding the usefulness of associated interpretations.

Magnetic resonance sounding (MRS) was performed to evaluate its applicability for characterising groundwater at selected locations in Aswan Governorate, Egypt. The MRS mainly detects a weak but noticeable alternating magnetic field as MRS signals when the proton spin in groundwater produces non-magnetic moments and rotates around the geomagnetic field, indicating the detection of groundwater. The MRS system was first correlated at a piezometer with a known water table depth (~80 m). Subsequently, three MRS sounding stations with unknown water tables were tested at Qism Aswan at ~ 18 km from the piezometer using NUMIS Auto magnetic resonance sounding system following the MRS site common practices. The MRS data were subjected to adaptive notch filtering to remove spiky noise and potential power line harmonics, and finally enhance the MRS signals at the selected stations. The water depth (~75-95 m) estimated from the MRS data around the piezometer largely coincides with the actual depth (~80 m) at the piezometer itself. A transient electromagnetic (TEM) profile performed near the measured MRS stations indicates no water content. Unlike the MRS data for NNL-1, the data for NNL-2 and NNL-3 match well with TEM data at shallow depths. The evaluation generally indicates that the MRS method is applicable for groundwater exploration at the selected piezometer and the other three stations. However, the method necessarily requires additional denoising efforts to comprehensively characterise groundwater occurrence and aquifer parameters.

Studying the biogeochemistry of shallow lake sediments, especially the source of sedimentary organic matter (OM), is challenging because of the low preservation of OM in shallow lake sediments. Here we report the source of sedimentary OM in a shallow freshwater lake, Verlorenvlei, in South Africa using a number of biogeochemical proxies. Elemental carbon and nitrogen ratio (C/N), and stable C and N isotopes (delta C-13 and delta N-15) indicate algal source of the sedimentary OM. Total organic and inorganic C, different phosphorus fractions, delta C-13 and delta N-15 values indicate repetitive presence of non-N-fixing cyanobacteria under moderate N-limited conditions. Cyanobacterial population in Verlorenvlei is likely influenced by the availability of dissolved inorganic C. Cyanobacterial proliferation in the lake has ceased with accelerated N input as recorded at the top of the core.

Multiple sulfur (δ 34 S sulfate , Δ 33 S sulfate , & Δ 36 S sulfate), nitrogen and oxygen (δ 15 N nitrate & δ 18 O nitrate) and strontium (87 Sr/ 86 Sr) isotope compositions of precipitation collected from Seoul, South Korea were analyzed to study the sources, transportation and deposition of air pollutants in East Asia. The δ 34 S sulfate values (from 1.9 to 14.6‰ with a median of 4.7‰) and the δ 15 N nitrate values (from-2.0 to 13.3‰ with a median of 1.0‰) suggest that fossil fuel use (emission from coal combustion and vehicle exhaust) is a predominant source for sulfur and nitrogen, but other natural sources including biogenic contributions of DMS also add to their total budget. The seasonal variations are observed in δ 34 S sulfate and δ 15 N nitrate values (both higher in winter season), which is likely to result from the increase of coal use for domestic heating in China. The δ 18 O nitrate values also varied seasonally depending on the NO x oxidation pathway, being about 20‰ higher in winter than in summer season. The Δ 33 S sulfate and Δ 36 S sulfate values are not anomalous, showing the absence of MIF signals in precipitation of Seoul. The 87 Sr/ 86 Sr ratio of the precipitation samples range from 0.70988 to 0.71487 with a median of 0.71073, indicating the influence of at least three end-member (silicate dust, carbonate dust and anthropogenic emission). Ionic ratios such as (K + +NH 4 +)/(Ca 2+ +Mg 2+) and Cl-/Na + suggest the overwhelming effect of anthropogenic input rather than carbonate dust on the end-member with lower 87 Sr/ 86 Sr ratios.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Radioactive isotope tritium ( 3 H) and stable isotopes of hydrogen ( 2 H/ 1 H) and oxygen ( 18 O/ 16 O) were measured during 2010 in the Sava River, precipitation and groundwater at 3 monitoring wells and 1 production well of the Petruševec aquifer, close to the Sava River in the Zagreb area. Significant increase of 3 H activity in the Sava River was observed in June, (200 ± 20) TU, and in groundwater of all wells with damped response (maximum 60 TU) and with delay of 3-5 months related to the Sava River. This increase was explained by release of tritiated water from the Krško Nuclear Power Plant, 30 km upstream from Zagreb in the beginning of June 2010. Stable isotope analyses showed similar range of δ 2 H and δ 18 O values for the Sava River and groundwater samples with higher variations in surface water. Differences in monthly variations of δ 18 O values between particular monitoring wells, together with 3 H values, indicated different infiltration times of surface water of the Sava River to different wells of the Petruševec aquifer.

Benthonic marine species show a wide range of biological reactions to seawater chemical changes through time, from subtle adjustments to extinction. The Early Toarcian Oceanic Anoxic Event (T-OAE) was recently recognized in the Neuquén Basin, Argentina, confirming its global scope. The event was identified

In this study, the effects of petroleum generation and expulsion on shale porosity is explored by evaluating the compaction of the Kimmeridge Clay Formation (KCF) within the oil window using log data and shale samples from the KCF within the depth and temperature range of ~1.5-5.0 km and 90-157ºC, respectively. Petrophysical properties e.g porosity and pore-size distribution were measured, and permeability was calculated using empirical models based on the measured porosities. Transit-time values from the sonic logs recorded at depths in the wells were the cores were recovered were calibrated against the porosities determined from the core samples. Bulk geochemical parameters e.g., Total Organic Carbon (TOC), Hydrogen Index (HI) were determined. The volume reduction in the KCF within the oil window due to petroleum generation and expulsion, and compaction due to loss of pore space was determined using the geochemical and log derived porosity data emplaced into empirical relations. Porosities above the oil window range from ~15-20%, but decreased to <5% at the end of the oil window. Pore-sizes decrease from ~11 nm to between 6-8 nm at the depth range of 1.5-5.0 km. Permeability decreased from 4.8 nD to ~0.095 nD. The quantitative estimations of volume reduction within the oil window indicate that for ~8.0wt% initial TOC sediment, a bulk volume reduction of 13% of the initial volume is due to oil expulsion, and ~12% is due to loss of pore space.

Realise dans le cadre d’un partenariat entre laboratoires universitaires (ENSEGID et CENBG), et le BRGM d’autre part et finance avec le soutien du Conseil General de Gironde et de l&#39;Agence de l&#39;Eau Adour-Garonne, ce travail vise a ameliorer la connaissance des systemes aquiferes du nord du Bassin aquitain. Au total 36 nouveaux points ont ete preleves dans les nappes du Miocene, de l’Oligocene, de l’Eocene, du Campanien, du Cenomanien et du Jurassique. Les cations et anions majeurs, et elements traces, les isotopes stables de l’eau (18O, 2H) et les isotopes du carbone (14C et 13C) ont ete analyses sur la totalite des echantillons, dans le but d’acquerir de nouvelles donnees dans des secteurs peu ou pas etudies avec ces outils. Ces mesures viennent enrichir les donnees deja disponibles issues de la litterature. C’est ainsi 127 mesures d’activite en 14C avec les mesures de 13C correspondantes qui ont pu etre utilisees pour recalculer des temps de residence. Nous disposons egale...

The ice giants Uranus and Neptune are the least understood class of planets in our solar system but the most frequently observed type of exoplanets. Presumed to have a small rocky core, a deep interior comprising ∼70% heavy elements surrounded by a more dilute outer envelope of H 2 and He, Uranus and Neptune are fundamentally different from the better-explored gas giants Jupiter and Saturn. Because of the lack of dedicated exploration missions, our knowledge of the composition and atmospheric processes of these distant worlds is primarily derived from remote sensing from Earth-based observatories and space telescopes. As a result, Uranus's and Neptune's physical and atmospheric properties remain poorly constrained and their roles in the evolution of the Solar System not well understood. Exploration of an ice giant system is therefore a highpriority science objective as these systems (including the magnetosphere, satellites, rings, atmosphere, and interior) challenge our understanding of planetary formation and evolution. Here we describe the main scientific goals to be addressed by a future in situ exploration of an ice giant. An atmospheric entry probe targeting the 10-bar level, about 5 scale heights beneath the tropopause, would yield insight into two broad themes : i) the formation history of the ice giants and, in a broader extent, that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. In addition, possible mission concepts and partnerships are presented, and a strawman ice-giant probe payload is described. An ice-giant atmospheric probe could represent a significant ESA contribution to a future NASA ice-giant flagship mission.

Biotic evolution was the consequence of repeated extinction and following diversification in the past, which was caused by large-scale environmental changes, in particular, by extremely rapid and drastic forcing that changed the environments of the biosphere. Irreversible and episodic changes in material cycling on the planet and in galactic cosmic radiation are nominated as major driving mechanism for the alleged rapid, large-scale environmental perturbations. The biodiversity change in the fossiliferous Phanerozoic record is characterized by 5 major mass extinctions within the long-term trend of diversity increase. Nonetheless, each extinction event has been explained rather in ad hoc manner, without any universal explanation. This session discusses the Phanerozoic biodiversity change under a new light of the recent progress in geology.

In het boek worden 35 ‘streefbeelden’ aangaande landschappelijke, cultuurhistorische en karakteristieke waarden op en rond de oevers van de Vecht besproken en toegelicht met veel actueel en historisch beeldmateriaal. De onderwerpen variëren van jaagpaden, zichtlijnen of de waterbank bij de Hinderdam tot forten, dakpanoevers of gaande ontwikkelingen als Opbuuren en fort Uitermeer. Van ieder onderwerp wordt de historische achtergrond geschetst, waarna de kansen en bedreigingen aan de orde komen. Het boek is hiermee een ‘Vechtvisie’ op de Vechtoevers,  dat als doel heeft een inspiratiebron te zijn voor overheden en particulieren om zelf aan behoud en ontwikkeling van de waarden van de Vechtoevers te werken.

Auteurs: Steven de Clercq (kansen en bedreigingen) en Juliette Jonker-Duynstee (historie). Landschappelijke ontwerpschetsen: Luc van Dam i.s.m. Jorn Copijn.

Dit rijk geïllustreerde boek neemt u in negen chronologische verhaallijnen mee in de boeiende geschiedenis van Stichtse Vecht en laat zien waar u deze ook echt kunt beleven. Het vertelt over de rijke gelaagdheid van ons cultuurlandschap. Over het ontstaan en de vroegste nederzettingen tot de bouw van kastelen en buitenplaatsen. Van de veenontginningen en de Hollandse Waterlinie, het Amsterdam-Rijnkanaal en de uitbreiding van de dorpen. Van de ontwikkeling van ons landschap tot het ‘buiten van de Randstad’ van vandaag de dag.
Informatieve teksten en veel beeldmateriaal geven een mooi overzicht in vogelvlucht van het landschap en de cultuurhistorie van Stichtse Vecht.

The succession of the Palaeoproterozoic Birimian belt of the Kedougou-Kenieba Inlier of western Senegal is subdivided into the Mako and Diallé-Daléma supergroups. The c. 2.2 Ga Mako Sgp consists of tholeiitic pillow lavas overlying gabbros and ultramafic rocks. The pillow lavas are overlain by metacherts, shales, and carbonate rocks. This assemblage represents a deep-water, oceanic crust succession. It is intruded by calc-alkaline plutons, and covered by calc-alkaline lavas and pyroclastic rocks of the upper Mako Sgp, representing an oceanic island arc. The Diallé-Daléma Sgp consists of a thick (8-10 km) volcano-sedimentary succession, with calcitic and dolomitic marbles, conglomerates, breccias, greywackes, sandstones, shales, and ash beds, possibly deposited in a back-arc basin [1]. Carbonate rocks of the Mako Supergroup lie directly above tholeiitic pillow lavas, with associated banded cherts and some thin organic-rich black shales. These rocks also include hyaloclastic breccias,...

The late Paleozoic deglaciation is the vegetated Earth’s only recorded icehouse-to-greenhouse transition, yet the climate dynamics remain enigmatic. By using the stable isotopic compositions of soil-formed minerals, fossil-plant matter, and shallow-water brachiopods, we estimated atmospheric partial pressure of carbon dioxide (pCO2) and tropical marine surface temperatures during this climate transition. Comparison to southern Gondwanan glacial records documents covariance between inferred shifts in pCO2, temperature, and ice volume consistent with greenhouse gas forcing of climate. Major restructuring of paleotropical flora in western Euramerica occurred in step with climate and pCO2 shifts, illustrating the biotic impact associated with past CO2-forced turnover to a permanent icefree world

Applied organic geochemistry provides the information needed to make maps of the richness, type, and thermal maturity of a source rock. These maps are a necessary step toward determining the stratigraphic and geographic extent of a pod of active source rock in a petroleum system, and they are based on geochemical analyses of rock samples from outcrops and wells that are displayed on logs. These geochemical well logs are based on Rock-Eval pyrolysis, total organic carbon, vitrinite reflectance, and other rapid, inexpensive "screening" methods. The logs define (1) potential, effective, and spent petroleum source rock; (2) the thermal maturation gradient, including immature, mature, and postmature zones, and (3) in situ and migrated petroleum shows. Useful geochemical logs require proper sample selection, preparation, analysis, and interpretation. Detailed studies, including oil-source rock correlations by biomarker and supporting techniques, are undertaken on selected samples only after the screening methods are completed.

This study examines mobility adaptations to a time of sociopolitical tumult in the ancient Andes. We examine 87 Sr/ 86 Sr variability in human burials (n = 21) dating to the Late Intermediate Period ("LIP," ca. 1100-1450 CE) in the Sihuas Valley, Arequipa, Peru. The LIP in the southern and central Peruvian Andes is characterized as a time of drought, inter-community violence, and balkanization. Grave goods reflect ties to the nearby highlands, so we examine whether any Quilcapampa burials were non-locals and characterize their intra-lifetime mobility. Materials and Methods: We report 87 Sr/ 86 Sr values from tooth enamel samples (n = 35) reflecting residential origins during three distinct periods during early-life, and bone (n = 12) reflecting origins averaged over the last years of life. We use 87 Sr/ 86 Sr isobiographies to identify individuals who were likely non-local to Quilcapampa at some point in their lifetimes. Because there are no extreme outliers, we define the cumulative local range as mean ±2σ of archaeological human samples, extended by the range of water 87 Sr/ 86 Sr within 10 km. We determine the proportion of probable non-locals and compare this and intra-lifetime mobility within Quilcapampa subgroups and between neighboring sites. Results: Two males from the northern sector exhibit non-local 87 Sr/ 86 Sr values, and the northern sector has a higher mean intra-lifetime 87 Sr/ 86 Sr range than the southern sector. Only 4.5% of burials exhibit non-local 87 Sr/ 86 Sr values at some point in their lifetimes-higher than contemporaneous highland sites, but low midelevation Arequipa valleys. Quilcapampa, however, shows a higher mean intra-lifetime 87 Sr/ 86 Sr range compared to neighboring mid-valley sites, possibly reflecting adaptive short-term mobility. Conclusion: Mobility for Quilcapampa individuals was likely constrained to nearby mid-valley communities and highlands, rather than long-distance travel. Immigrants likely leveraged pre-existing intra-regional mobility networks between neighboring valleys with similar geological characteristics. Tweetable Summary: 87 Sr/ 86 Sr isobiographies show limited intra-lifetime mobility in LIP Sihuas Valley, Peru.

A combined hydrogeochemical and hydrodynamic characterization for the assessment of key aspects related to groundwater resources management was performed in a highly productive agricultural basin of the Thessaly region in central Greece. A complementary suite of tools and methods—including graphical processing, hydrogeochemical modeling, multivariate statistics and environmental isotopes—have been applied to a comprehensive dataset of physicochemical analyses and water level measurements. Results revealed that the initial hydrogeochemistry of groundwater was progressively impacted by secondary phenomena (e.g., ion exchange and redox reactions) which were clearly delineated into distinct zones according to data processing. The progressive evolution of groundwater was further verified by the variation of the saturation indices of critical minerals. In addition, the combined use of water level measurements delineated the major pathways of groundwater flow. Interestingly, the additional...

Beetle exoskeletons contain chitin, a poly amino-sugar that is biosynthesized incorporating hydrogen isotopes from diet and water. As the stable isotope ratios D/H (or 2 H/ 1 H, expressed as dD values) of precipitation and diet are jointly influenced by climate, the biochemically recorded hydrogen-isotope ratio in fossil beetle exoskeleton has the potential to be used for paleoclimatic reconstruction. New dD data from modern beetles are presented as a preliminary database for Europe, with a re-evaluation of earlier North American data. We present correlated matrices of dD values in modern beetle chitin and modern precipitation to demonstrate the concept. We review the pertinent literature to highlight the history, utility, and likely future research directions for the use of chitin's stable isotopes in entomological paleoclimatology.

Museum collections contain a wealth of insect remains originating from a wide geographic range, which can be used to investigate their utility as a proxy for environmental isotope ratios. Chitinous remains of insects such as beetles (Coleoptera) are chemically stable and their stable isotope composition is strongly related to that of environmental water in the period of cuticle formation. We present a dataset of chitin dD and d 18 O in two genera of water beetles from a museum collection containing 40 locations for Helophorus (water scavenging beetles) and 48 locations for Hydroporus (predaceous diving beetles) that were selected from latitudes 27-82°N in North America. Only two genera were used to minimize inter-sample variation caused by species-specific differences in metabolic effects, feeding strategy, habitat, and life cycle. The isotopic composition of water beetle exoskeletons had a strong latitudinal trend (North-South) from -160 to ?65 % for dD and from 7 to 34 % for d 18 O, paralleling gradients of isotopes in precipitation. Strong relationships were observed between isotopic composition of beetles and modelled July precipitation (0.71 \ R 2 \ 0.82, p \ 0.001). The relationship between dD and d 18 O in the beetle samples had a systematic offset from the global meteoric water line, which was likely caused by metabolic effects during chitin formation. The offset between dD values in beetles and in modelled precipitation was 33 % larger, on average, for Hydroporus compared with Helophorus, suggesting fractionation of hydrogen isotopes during passage through the food chain. This trophic level effect was not observed for stable oxygen isotopes. Furthermore, the observed deviations between isotopic composition of water beetles and modelled precipitation at collection sites were not constant and indicated local hydrological deviations from modelled precipitation. The largest deviations were observed for sites in the Southern US and the Arctic that are highly evaporative and at sites in the Rocky Mountains and Coastal Mountains that were fed by snow melt. Our results indicated that the isotopic Electronic supplementary material The online version of this article (

The oceanic anoxic event in the Early Toarcian, often referred to as the ‘Torcian Oceanic Anoxic Event’, led to widespread deposition of organic‐rich black shales and geochemical anomalies in elemental distribution and multiple isotope systems in the Early Jurassic ocean. Best characterized by its hallmark carbon isotope anomaly, the event is widely regarded as a prime example of rapid greenhouse warming‐related changes in the Mesozoic Earth system. However, despite numerous studies, details of its forcing mechanisms, exact duration and the role of regional effects remain debated. This article presents new data (high‐resolution organic carbon isotope, calcareous nannofossil and elemental geochemical analyses) from the black shale‐bearing Lower Toarcian section in the Réka Valley, Hungary, with the aim of assessing any regional differences in the sedimentary and geochemical record and their bearing on the underlying oceanographic and climatic processes. Following a short segment with...

A vertical section of Upper Paleozoic sandstones from southern Transdanubia (Mecsek-Villány area, Tisza mega-unit, Hungary) has been analyzed for major and trace elements, including rare earth elements (REEs). In addition, the clay mineralogy of the sandstone samples and the petrography and geochemistry of gneiss and granitoid clasts extracted from the associated conglomerates have been determined. Geochemistry of the sandstone samples analyzed in this study shows that these rocks were predominantly derived from a felsic continental source; nevertheless, compositions vary systematically up-section. The Pennsylvanian (Upper Carboniferous) Téseny Formation has higher SiO 2 and lower Na 2 O, CaO, Sr, high field strength element (HFSE), and ΣREE contents relative to the Permian strata. Its high K 2 O and Rb contents together with the presence of abundant illite-sericite suggest a potassium metasomatism in this formation. Clay mineralogy and large ion lithophile element (LILE) contents of the Lower Permian Korpád Formation vary spatially and are interpreted as local variations in composition of the source region and postdepositional conditions. Zr and Hf abundances and REE patterns, however, show that this formation was derived from mature upper continental crust. The Upper Permian Cserdi

The Ballık continental carbonates were geochemically characterized using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and a δ 18 O, δ 13 C and strontium stable isotopic analysis. The geochemical delineation of the lithofacies, characterizing certain depositional environments, can be used in a chemo-stratigraphic approach to correlate the geobodies. Based on the stable isotopic composition the fluido characteristics and possible source rocks are deduced. The combination of these results contributes to the reconstruction of the depositional history of the studied travertines. The continental carbonates are characterized by low trace element concentrations compared to marine carbonates, with the exception of high strontium concentrations. Aluminum, iron, nickel, titanium and silicon show similar trends within the different vertical lithologs, what makes them suited for correlation. Progressive alteration due to diagenetic stabilization with meteoric waters, as described by Brand and Veizer (1980), is recognized by a decrease of strontium, sodium, magnesium and a coinciding increase of manganese and iron towards the top of the different sections. The Ballık continental carbonates have δ 13 C values between -3.83 and 2.60 ‰ V-PDB and δ 18 O values from -9.39 to -5.72 ‰ V-PDB. δ 13 C values decrease towards the top of the different vertical sections, while δ 18 O stays more or less constant. The 87 Sr/ 86 Sr isotopic ratio for the analyzed samples is 0.70786 ± 0.00005. These results point to deposits from a fluid, that inherited the carbon and strontium isotopic signature of dissolved Triassic marine carbonates, and indicate the Lycian Nappes as possible source rock.

The Degree of Pyritization (DOP) and the Indicator of Anoxicity (IA) were used as tools to assess the degree of redox conditions in Lower and Middle Jurassic strata from Bulgaria. Normally-oxygenated (with DOP values < 0.45 and IA values < 0.4), oxygen-restricted (0.45 < DOP < 0.7; 0.4 < IA < 0.5), and oxygen-depleted (DOP > 0.7 and IA > 0.5) bottom-water conditions were recognized on a selection of samples, mainly from the Ozirovo Formation (upper Pliensbachian-Toarcian), but also from the Etropole Formation (lower Bajocian). DOP and IA yielded the highest values (> 0.9 for DOP and > 0.5 for IA) from samples of the lower Toarcian Tenuicostatum and Falciferum ammonite zones, and thus, denoted declined oxygen levels and enrichment of reactive Fe at the sea floor. Beyond this stratigraphic level, both parameters indicated for prevailing normally-oxygenated to oxygen-restricted setting, with limitedly imposed environments beneath stratified water-column.

The Degree of Pyritization (DOP) and the Indicator of Anoxicity (IA) were used as tools to assess the degree of redox conditions in Lower and Middle Jurassic strata from Bulgaria. Normally-oxygenated (with DOP values &lt; 0.45 and IA values &lt; 0.4), oxygen-restricted (0.45 &lt; DOP &lt; 0.7; 0.4 &lt; IA &lt; 0.5), and oxygen-depleted (DOP &gt; 0.7 and IA &gt; 0.5) bottom-water conditions were recognized on a selection of samples, mainly from the Ozirovo Formation (upper Pliensbachian–Toarcian), but also from the Etropole Formation (lower Bajocian). DOP and IA yielded the highest values (&gt; 0.9 for DOP and &gt; 0.5 for IA) from samples of the lower Toarcian Tenuicostatum and Falciferum ammonite zones, and thus, denoted declined oxygen levels and enrichment of reactive Fe at the sea floor. Beyond this stratigraphic level, both parameters indicated for prevailing normally-oxygenated to oxygen-restricted setting, with limitedly imposed environments beneath stratified water-column.

Dietary shifts and corresponding morphological changes can sometimes evolve in succession, not concurrently—an evolutionary process called behavioral drive. Detecting behavioral drive in the fossil record is challenging because it is difficult to measure behaviors independently from corresponding morphologies. To solve this problem, we focused on a puzzling behavior in the fossil record of some primates: eating graminoid plants. We report carbon and oxygen isotope ratios from fossil cercopithecid monkeys and integrate the data into a view of hominin dietary evolution, finding that changes in graminivorous behavior preceded corresponding changes in dental morphology by ~700,000 years. Decoupling diets and morphologies in time was conducive to determining when and to exploring why dietary changes helped to propel human evolution.

Van 2017 tot 2020 wordt gebouwd aan een splinternieuw station Driebergen-Zeist. De hele omgeving gaat op de schop waarbij het streven naar bereikbaarheid, veiligheid en duurzaamheid belangrijke drijfveren zijn.  Te midden van de indrukwekkende bouwwerkzaamheden kre
gen archeologen de kans om de bodem te onderzoeken en letterlijk een kijkje te nemen in het verleden.

CAIs (Calcium-, Aluminum-rich Inclusions) are white inclusions found in carbonaceous chondrites. They are made of calcium-and aluminum-rich oxides and silicates. They are among the oldest solids of the solar system. They provide clues on the immediate environment of the nascent solar system and on its earliest phases.

Rainfall isotopic composition is a valuable source of data to understand and model the complexity of hydrological systems. The identification of water recharges origins, water flow trajectories and pollutants movement in the hydrologic cycle can greatly benefit from this information. It is also very useful in other environmental forensic applications. However, its use has been strongly limited by the availability of data. A major challenge is to extend sparse measurements of stable isotopes data to surrounding geographic areas taking into account other secondary variables as latitude, altitude and climate related parameters. In Spain the network REVIP, made up by 16 nodes, maintained by governmental agencies, provides continuous recorded data of O-18 in meteoric precipitation since the year 2000. So far, only regression models have been proposed to map stable isotopes against latitude and altitude. Yet, these maps maintain small residuals at the network nodes that are possibly cause...

The stable carbon (d13C) and nitrogen (d15N) isotope analysis of charred
archaeological grains provides a remarkably precise scale of information: the
growing conditions under which a plant was cultivated in a single field and
season. Here we investigate how the measurement of single individual grains or aggregate “bulk” samples for carbon and nitrogen isotopes impacts how we characterize variation and, consequently, our interpretations of ancient cultivation practices. Using experimentally grown barley (Hordeum vulgare var. nudum), this work investigates d13C and d15N intra-panicle variation between both uncharred and charred individual grains from four plants. We found limited intra- and inter-panicle isotopic variation in single-grain isotope values, ca. 0.5‰ in d13C and ca. 1‰ in d15N, reemphasizing the degree to which grains are representative of their local growing conditions. To explore the interpretive impact of aggregate versus single-grain isotopic sampling, we measured charred barley recovered from a single storage context excavated from Trench 42 (ca. 1,900 BCE) at Harappa. Aggregate samples of a random selection of Trench 42 barley demonstrated remarkable inter-sample homogeneity, with a <0.5‰ difference in d13C and d15N values, demonstrating aggregate samples capture well a representative isotopic average of a single depositional context. However,
the measurement of single grains revealed moderate 2–3‰ variation in d13C
and an outstandingly wide isotopic variation of ca. 8‰in d15N values, indicating the degree to which growing conditions varied beyond what the isotope ratios from aggregate samples indicated. These results highlight how decisions in the selection and measurement of archaeological charred grains for isotopic analysis impact data resolution, with profound consequences for understanding past agricultural diversity.

Main purpose of this paper is to determine the mineralogical composition and mechanical properties of the Tarkwaian Supergroup and compare them. This project will help determine whether the rock units of the Tarkwaian Supergroup are competent based on their mineral contents and strength of the rocks to be quarried and used as aggregates for construction and also determine the structural features that were formed in the various rock units due to the deformation that took place. Values obtained from the Unconfined Compressive Strength (UCS) test were (21.50-77.10) N/mm 2 with the Kawere conglomerate having the lowest, and Tarkwa Phyllite having the highest strength. The Huni sandstone, Banket Quartzite and Kawere conglomerate were classified as weak rocks, but the Tarkwa Phyllite was classified as a medium rock, according to classification. The Huni sandstone, Banket Quartzite and Kawere conglomerate are made up of grains of varying degrees of roundness and maturity. The Huni sandstone, Banket Quartzite, and Tarkwa Phyllite exhibit foliation. Micro-folding is also observed in the Kawere conglomerate. Petrographic studies of the rocks classify them as metasedimentary rocks weathering. Based on the weak strengths of the various rock units, they are not suitable to be used as aggregates for construction but can be used for other purposes such as construction sand and dimension stones.

Molecular oxygen has been detected in the coma of comet 67P/Churyumov-Gerasimenko with abundances in the 1%-10% range by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis-Double Focusing Mass Spectrometer instrument on board the Rosetta spacecraft. Here we find that the radiolysis of icy grains in lowdensity environments such as the presolar cloud may induce the production of large amounts of molecular oxygen. We also show that molecular oxygen can be efficiently trapped in clathrates formed in the protosolar nebula (PSN), and that its incorporation as crystalline ice is highly implausible, because this would imply much larger abundances of Ar and N 2 than those observed in the coma. Assuming that radiolysis has been the only O 2 production mechanism at work, we conclude that the formation of comet 67P/Churyumov-Gerasimenko is possible in a dense and early PSN in the framework of two extreme scenarios: (1) agglomeration from pristine amorphous icy grains/ particles formed in ISM and (2) agglomeration from clathrates that formed during the disk's cooling. The former scenario is found consistent with the strong correlation between O 2 and H 2 O observed in comet 67P/Churyumov-Gerasimenko's coma while the latter scenario requires that clathrates formed from ISM icy grains that crystallized when entering the PSN.

The Darn6 Conglomerate and the P6tervfis~a Sandstone with conglomeratic intercalations, both cropping out in northern Hungary, were formed along the eastern margin of the shallow Early Miocene sea within the Carpathian arc. Ophiolite-derived clastic components in both formations indicate a close genetic relationship with each other and with the activity of the basin-margin Darn6 Fault, which seems to correspond with the coeval shoreline. The Dam6 Conglomerate was part of a small fault-controlled fan-delta supplying coarse clastics into the sea where the P6tervfis~a Sandstone deposited. The conglomerates occur as small lobes interbedded within a field of tidally-driven sand waves. The coarse-grained clastics, which were admixed to the main material of the sandstone, have been derived from Triassic-Jurassic ophiolite-related series (Meliata nappes) east of the Darn6 Fault. The composition of the lobes indicates that they were formed as small spit-like platforms attached to the fan-deltas of the Darn6 Conglomerate. As base level rose spits became drowned and their sediment was washed into the basin and reworked by the strong northward-directed tidal currents into elongated lobes 'mimicking' sand waves. A reduction in the amount of the less resistant pebble components of ophiolite-related origin and a relative enrichment of the resistant components towards the west indicate that pebbles had partly been transported in the offshore direction. The increasing rate of accumulation of ophiolite-derived heavy minerals and pebbles along the northern part of the coast indirectly suggests a contemporaneous left-lateral displacement along the basin-margin Darn6 Fault.

Plummer et al. set-up is suitable to study the induced RCA tufa precipitation. Garrels-Mackenzie model predicts the composition and mechanism of RCA tufa formation. Calcium sulfate compounds are dominant in evaporative RCA Tufa. Calcium carbonate compounds are dominant in artificially CO 2 saturated environments. Formation of evaporative tufa is more favorable for using RCA in construction.

As significant indicators of deep-time palaeoclimate, a number of new palaeontological, pedological and geochemical characteristics are provided for the Chemnitz Fossil Lagerstätte to depict more precisely its environmental conditions. For the first time, several lines of evidence indicate that this fossil forest, instantaneously preserved by volcanic deposits, once received an annual precipitation of around 800-1100 mm, but grew on a nearly unweathered palaeosol. Although the composition of this rich and diverse T 0 assemblage suggests a hygrophilous, dense and multi-aged vegetation dominated by conservative lineages, the habitat was affected by environmental disturbances and pronounced seasonality. Repeated changes in local moisture availability are suggested by geochemical proxies, the co-occurrence to intergrowth of calcic and ferric glaebules in the palaeosol and developmental traits of perennial vegetational elements. Specific substrate adaptation is reflected by different root systems and cyclic growth interruptions recorded in the stems, branches and roots of long-lived woody plants. Many differentially adapted terrestrial animals complete the more comprehensive reconstruction of a late Sakmarian ecosystem and its climatic and preservational controls. Albeit spatially confined, this diverse in-situ record may contribute to understand wetland-dryland dynamics of sub-tropical Northern Hemisphere Pangaea.

The Brahmaputra river system is one of Asia's largest and most dynamic transboundary rivers. Yet, significant investigations on the isotopic signature of its water are limited and not documented. This study aims to address the limitations in datasets and enhance the knowledge of the river's complex hydrological processes and its climatic influence using the stable isotope technique. Over 1-2 years, a comprehensive dataset of isotopes was gathered from multiple locations within the basin to study the continuous changes in precipitation, groundwater, and surface water. Seasonal observations were also conducted along different parts of the lower Brahmaputra river system, from its entry point in Indian territory to its lower reaches in the Assam valley. The isotopic composition reflects contributions from various sources such as glacial melt, snowfall, rainfall, and groundwater that flow into the river water. Seasonal isotopic variations in precipitation show depleted signatures during the post-monsoon due to intense rainout, resulting in enrichment in the remaining water vapour. Enriched values of precipitation during the pre-monsoon indicate significant evaporation. Spatial variation in river water points to isotopic depletion in upstream regions due to snowmelt and glacial contributions, while downstream reaches display isotopic enrichment from heavy precipitation

Si bottom! SI Figure 3: Geographic distribution of the samples complying with the 1-mile distance to the coast (shaded area). SI Figure 4: Relationship between total marine diatom abundance ln (# valves /g) and a 47yr mean annual geostrophic Ekman transport determined upwelling index, for the total dataset. Color scheme as in Figure 1.

The isotopic compositions of noble gases in the solar wind show high enrichments of light isotopes. When corrected for mass fractionation all five noble gases there can be resolved in terms of the two primitive noble gas components that have been identified in planetary solids. Reasons are presented for assigning the fractionation to a solar process that selectively enriches lighter nuclei at the surface of the Sun. When abundances of the elements at the Sun&#39;s surface are corrected for this fractionation, it is shown that atomic abundances for major elements in the bulk Sun are (in decreasing order): Fe, Ni, O, Si, S and Mg. Solar elements at about the 1% atomic abundance level include He, C, Ne, Ca and Cr. These results suggest that fusion of hydrogen is probably not the Sun&#39;s primary energy source.

Aim  This study aims to separate regional and local controls on Holocene vegetation development and examine how well pollen records reflect climate change in a semi‐arid region. The relative importance of climate and human activity as agents of vegetation change in the Sahel during the late Holocene is also considered.Location  Jikariya Lake, an inter‐dune depression in the Manga Grasslands of north‐eastern Nigeria.Methods  Pollen and charcoal were used to provide a record of Holocene vegetation history. Palaeoclimate and hydrological changes were reconstructed from sedimentary and geochemical data. Regional and local influences were separated by comparing the evidence obtained from Jikariya Lake with previously published data from the Manga Grasslands.Results  The Manga Grasslands experienced a prolonged wet period during the early and mid‐Holocene, during which swamp forest vegetation with Guinean affinities (Alchornea, Syzygium, Uapaca) occupied the inter‐dune depressions. Howeve...