Dissertations / Theses on the topic 'Radiogenic and stable strontium isotopes'

Au début des temps modernes (16ème - 18ème siècles), la construction de grands navires était primordiale pour le développement des rencontres culturelles dans ce qui est devenu l'âge de la découverte et de l'expansion européenne. L’Espagne était une des grandes puissances de l’époque. Le projet européen « ForSEAdiscovery » cherche dans ce contexte à répondre aux questions clés suivantes : les ressources forestières ibériques de l’époque soutenaient-elles la demande croissante de bois, ou bien ce bois était-il importé d’autres pays ? Si ces bois ne provenaient pas de l’Espagne, comment les réseaux de commerce étaient-ils organisés ? Ce projet aborde ces questions à travers un programme de recherche multidisciplinaire et innovant pour améliorer la compréhension de notre passé historique et de notre patrimoine culturel, et développer notre connaissance sur l'utilisation passée des ressources en bois pour la construction navale. L'objectif de cette thèse, qui s’insère dans ce projet, est d’identifier la provenance des bois utilisés dans la construction navale ibérique en utilisant des traceurs géochimiques. L’hypothèse est que les arbres se développant sur des roches et des sols contrastés possèdent des signatures géochimiques spécifiques héritées des roches. Les signatures isotopiques en strontium (87Sr/86Sr) peuvent notamment être des indicateurs de provenance géographique. Dans ce contexte, la démarche suivie dans la thèse a consisté à caractériser la signature isotopique en Sr dans des bois d'épaves de bateaux et dans les bois d’arbres actuels, les sols et roches prélevés dans les principaux peuplements forestiers espagnols pointés comme lieux de production des bois entre le 16ème - 18ème siècles. Les signatures en δ88/86Sr, traceur peu connu encore, ont également été caractérisées dans les échantillons. Les types et les âges des roches ont été caractérisés et les liens entre les rapports isotopiques 87Sr/86Sr et δ88/86Sr dans les roches, sols et arbres ont été étudiés sur les sites espagnols échantillonnés. La signature locale des sites espagnols potentiels de provenance de bois a été déterminée. Nos résultats mettent en évidence que le rapport isotopique 87Sr/86Sr dans les arbres reflète la signature de la fraction échangeable des sols sur lesquels ils croissent alors que le δ88/86Sr est affecté par le fractionnement, les isotopes légers (86Sr) étant préférentiellement incorporés dans les arbres laissant la fraction échangeable du sol enrichie avec les isotopes lourds (88Sr). Ce fractionnement observé pour les chênes, n’est pas marqué dans le bois des pins suggérant que le fractionnement isotopique durant le transfert du Sr entre le sol et l’arbre est dépendant de l’espèce. La contamination des bois d’épaves par les éléments marins a été identifiée. Le Sr marin se retrouve notamment sous forme adsorbée ou dans la structure des minéraux précipités dans les bois immergés. Différentes expériences d’extractions ont été testées et un protocole adapté a été développé pour extraire les éléments marins et retrouver la signature originelle du bois archéologique. Nous avons réussi à valider un protocole d’extraction et retrouver la signature originelle d’un échantillon de bois d’épave. Ce résultat souligne le potentiel et l’importance d’une nouvelle méthode combinant 87Sr/86Sr et δ88/86Sr pour des futures études de provenance de bois ou autres matériaux. Cependant, nos résultats indiquent également que beaucoup de nos échantillons de bois archéologiques n’ont pas conservé leur Sr originel. Partant de ce constat, des préconisations sont proposées pour améliorer la possibilité d’utilisation de ce traceur dans les études futures de provenance de bois archéologiques sous-marins
In the Early Modern Age (16th - 18th centuries), the construction of ocean-going ships was paramount to the development of cultural encounters in what became the Age of Discovery and European expansion. Spain was one of the biggest forces of that time. The European project “ForSEAdiscovery” seeks answers in this context to the following key questions: Could Spanish forest resources sustain the increasing demand of timber, or were the wood imported from elsewhere? If Spanish forests were not the only wood supplier, how were the trade networks organized? This project will address these questions through a multidisciplinary and innovative training research program to improve the understanding of our historical past, our cultural heritage, and our knowledge of the use of resources for shipbuilding. The objective of this PhD thesis, taking part of this project, is to identify the provenance of the Iberian shipbuilding wood using geochemical tracers. The hypothesis is that trees growing on contrasted rocks and soils have specific geochemical signatures, which can be an indicator of geographic provenance. In this context, the Sr isotopic signature (87Sr/86Sr) was characterized in shipwreck wood samples and wood from living trees, soils and rocks collected from the Spanish forest stands indicated as potential source of wood between the 16th - 18th centuries. The δ88/86Sr signatures were also characterized in the samples. The rock types and ages were characterized at the selected sites and the link between the 87Sr/86Sr and δ88/86Sr in rocks, soils and trees was studied on the sampled Spanish sites. The local signature of Spanish potential sites was determined for provenance of wood. Our results indicate that 87Sr/86Sr isotope ratios in trees reflect the signature of the corresponding soil exchangeable pool while δ88/86Sr was shown to be affected by mass-dependent fractionation with trees taking up lighter (86Sr) isotopes, leaving the soil exchangeable pool enriched with the heavier isotopes (88Sr). This fractionation observed for oak trees, was not found in pines suggesting that the isotopic fractionation during tree uptake is species dependent. The contamination of wood from shipwrecks by seawater elements was identified. Marine Sr was found to be adsorbed on the wood or included in the precipitated minerals in the waterlogged wood. Several extraction experiments were tested and an adapted protocol was developed to extract the seawater elements and retrieve the original signature of the archaeological wood. We succeeded to validate an extraction protocol and retrieve the original signature of one wood sample. This result underline the potential and importance of a new method combining 87Sr/86Sr and δ88/86Sr values for future provenance studies on wood or other materials. However, our results also indicated that most of our shipwreck wood samples did not conserve their original Sr. Therefore, preconizations were suggested in order to extend the use of this tracer in future provenance studies on archaeological wood from shipwrecks

De par sa position, le Golfe du Lion est un site idéal pour l’investigation des changements paléo-environnementaux et des processus affectant le dépôt sédimentaire. Les travaux antérieurs ont permis de mettre en évidence les impacts de la variabilité climatique et glacioeustatique sur l’organisation stratigraphique de la marge, mais également sur les exports terrestres de matière organique.L’étude isotopique du carbone organique et de l’azote de la matière organique dans les sédiments du forage PRGL1-4 nous a permis de mettre en évidence de forts exports fluviaux lors des interstades survenus au cours des 200 000 derniers milles ans. La mise en regard de cette découverte avec les enregistrements paléo-climatologiques terrestre et marin disponibles dans la région indique que ces forts exports fluviaux résultent d’une augmentation des précipitations le long de la bordure Nord Méditerranéenne. Grâce à la position dePRGL1-4, nous proposons que ces pluies soient le résultat d’une augmentation du passage de dépressions Nord Atlantique dans le bassin Ouest Méditerranéen.Une caractérisation des isotopes du soufre préservés dans la pyrite sédimentaire a été réalisée. Les résultats obtenus ont permis de mettre en évidence une variation isotopique insoupçonnée, l’une des plus grandes observées de nos jours, dont la cyclicité semble indiquer un fort contrôle climatique. Nous proposons deux mécanismes influençant le fractionnement isotopique: une modulation de l’activité bactérienne par le climat, et/ou (ii) une modulation locale liée la nature des sédiments impliqués dans la formation des pyrites en lien avec les variations eustatiques
By its position, the Gulf of Lion is an ideal location for investigation of past ecological changes and processes affecting the sedimentary deposition. Previous work has highlighted the impacts of climatic and glacio-eustatic changes on the GoL stratigraphic organization, but also on terrestrial exports of organic matter.This isotopic study based on the organic carbon and nitrogen preserved in PRGL1-4 sediments highlights important rivers runoff during warm periods of the last 200 000 years.Regional intercomparison with terrestrial and marine records indicates that these river exports resulting from an increase of precipitation over the North Mediterranean borderland.Using PRGL1-4 location, out of Mediterranean cyclogenetic area, we suggest that these pluvial events occurred in response to enhance passage of North Atlantic atmospheric perturbation into the Western Mediterranean basin.Pyrite sulfur isotopes investigations over the last 500 kyr have also been done. The stratigraphic variations (up to 76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial-interglacial sea level. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records. Two different mechanisms influencing the isotopic fractionation can explain the observed dataset: a climatic modulation of the bacterial activity, and / or (ii) a local sedimentary modulation involve during early diagenetic formation of pyrite in relation with the eustatic variations

The work reported in this thesis applies a new isotope tracer, stable strontium isotopes (δ^88/86Sr), to address questions concerning changes in global climate that occur in response to continental weathering processes, and to constrain the modern marine geochemical Sr cycle. Stable Sr isotopes are a relatively new geochemical proxy, and as such their behavior needs to be understood in differing forms of marine calcium carbonate, the archives from which records of past stable Sr variability in the oceans can be constructed. Foraminifera, coccoliths and corals (both aragonite and high Mg calcite) acquire δ^88/86Sr values lighter than that of modern day seawater, (approximately 0.11, 0.05, 0.2 and 0.19 ‰ lighter than seawater at ~25°C respectively) providing a measureable offset which can be used to constrain the modern Sr outputs from the ocean and provide a better understanding of the modern Sr cycle. Using foraminifera as a sedimentary archive the first marine δ^88/86Sr record of seawater over the last two glacial cycles has been constructed, and used to investigate changing carbonate input and output over this 145 kyr period. Modelling of the large excursion of δ^88/86Sr to heavier values during Marine Isotope Stage (MIS) 3, reveals that this is more likely to be due to local changes in seawater or post-depositional alteration, rather then whole ocean changes. In the terrestrial environment δδ88/86^Sr has been measured in the dissolved load of rivers from the Himalaya. It is found that, in general, rivers draining carbonate catchments possess lighter isotopic δ^88/86Sr values than those from rivers draining silicates. Covariations of either δ88/86Sr vs. δ30Si or δ^88/86Sr vs. 1/[Sr] can be used to distinguish between rivers draining different catchment areas.

This thesis concerns the application of a new technique for measuring the stable isotopes of Sr, specifically pertaining to mass dependent fractionation in high temperature processes on the Earth and Moon. Processes such as mantle melting and differentiation on Earth and the formation of the Lunar Magma Ocean are investigated by the application of a double-spike TIMS method to terrestrial and lunar material to obtain high-precision ⁸⁷Sr/⁸⁶Sr, ⁸⁸Sr/⁸⁶Sr and ⁸⁴Sr/⁸⁶Sr data. Measurements of mantle-derived mafic material provide insights into the ⁸⁸Sr/⁸⁶Sr composition of the silicate mantle. Ocean Island Basalts possess restricted δ⁸⁸Sr compositions, whilst Mid-Ocean Ridge Basalts from the Pacific, Atlantic and Indian ridges reveal variations in δ⁸⁸Sr, the majority of which is seen within the FAMOUS section of the Mid-Atlantic Ridge. These variations are attributed partly due to the effects of plagioclase crystallisation and partly due to mantle source heterogeneity. Analyses of mineral separates from three different igneous systems provide an understanding of δ⁸⁸Sr fractionation at a mineral-scale. The possibility of δ⁸⁸Sr fractionation as a result of magmatic differentiation has also been assessed, and found to occur between the basalt and rhyolitic end-members of the Icelandic Hekla suite. Variations in the ⁸⁷Sr/⁸⁶Sr ratios of these rocks are also found, and considered most likely to be due to contamination. Analyses of lunar rocks indicate that the highland suite appears to be relatively uniform in δ⁸⁸Sr, whilst significant fractionation to light δ⁸⁸Sr compositions occurs in the mare basalts. Such variations are thought to be associated with the crystallisation of plagioclase during the differentiation of the lunar magma ocean. Lastly, precise ⁸⁷Rb/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr data yield a model age for the Moon of 4.523 ± 0.019 Ga.

We test the fidelity of shallow-water gastropod skeletons as multi-proxy archives of seasonal paleo-environmental change by performing isotopic and trace-metal analyses on specimens of Conus ermineus from the Gulf of Mexico. Four adult specimens were collected from Stetson Bank in the Flower Garden Banks National Marine Sanctuary during the summer of 2002. Shell samples were milled along axes of growth to produce time-series profiles spanning up to eight years. We corrected the profiles for growth rate effects and compared the tuned results with in situ temperature and salinity records at the reef surface and temperature profiles from nearby surface buoys. Examination of sample densities in δ18O cycles shows that shell growth is faster during summers and slower during winters. Tuning the profiles versus time yields δ18O values that co-vary closely with seasonal temperatures to a high degree of coherency (R2 = 0.84). The δ13C profiles show cyclic variation modified by ontogenetic decreases in δ13C. These ontogenetic trends are attributable to decreasing metabolic efficiency, while seasonal cycles reflect hydrographic changes in the gastropods’ habitat. Salinity and δ13C of dissolved inorganic carbon show a strong correlation at Stetson Bank (R2 = 0.80), and early summer shell δ13C minima coincide with local salinity minima during times of peak river discharge. The terminations of these δ13C minima occur during annual upcoast reversals of shelf currents in this area. These effects are augmented by summer stratification and productivity minima that further decrease seawater δ13C. Sr/Ca ratios increase through ontogeny, most likely due to decreasing metabolic efficiency. However, seasonal variations in Sr/Ca profiles show strong similarity with δ18O profiles, confirming the temperature dependence of Sr/Ca and minimal influence of salinity on shell δ18O at Stetson Bank. The results of this study show that tuned δ18O and Sr/Ca profiles can be used to reconstruct seasonal paleotemperatures. Carbon isotope profiles and environmental data also demonstrate the utility of Conus δ13C as a proxy for freshwater flux and shelf circulation.

In this work, I present a multi-isotopic study (carbon, nitrogen, sulfur, strontium and lead) and Re-Os geochronology in rocks and crude oils of the Sonda de Campeche Petroleum System (SCPS). Since crude oils are complicated chemical systems easily disturbed, the Re-Os isotopic system could be affected if secondary processes perturb crude oils. Therefore, the multi stable isotopic study allows the identification of the presence and grade of these secondary processes in crude oils. The δ13C values of crude oils from the SCPS distinguish between: 1) crude oils with the fingerprint of source rocks of hydrocarbons (-28.3 to -26.7 ‰), and 2) crude oils with the fingerprint of the reservoir rocks (-25.5 to -24.9 ‰). Similarly, the δ15N values reveal that crude oils, during migration or trapping processes mimic the isotopic composition of the reservoir rocks of the Ek-Balam Formation. Furthermore, the δ34S values of crude oils from the SCPS (-8.0 to -2.5 ‰) show an absence of a thermal sulfate reduction (TSR) signature, which likely means that the use of Re-Os systematics in crude oils and rocks in the SCPS is appropriate. Strontium and lead measurements show crude oils have an isotopic composition different from rocks from the Edzna Formation but similar to rocks of the Akimpech and Ek-Balam formations, indicating that crude oils received Sr and Pb from the trapping rocks during migration or trapping processes, producing a isotopic mixing trend with rocks of these formations. Specifically, the lead isotope composition allows the identification of a source of lead never recorded before, the Guichicovi Complex. The isotopic data suggest that this Grenville Complex has been feeding with detrital material to the sedimentary rocks from Bacab, Ek-Balam and Akimpech formations in the SCPS, and in consequence contributing to the final isotopic composition of crude oils as well. Re-Os geochronology of rocks from the Edzna and Akimpech formations (152 ± 4 Ma; and 158.6 ± 5.5 Ma, respectively) provides precise ages of deposition that coincide with the ages proposed in previous studies based on the fossil record. Re-Os geochronology in crude oils yield ages with low uncertainty and moderate MSWD values, reflecting a rapid formation and migration process that occurred during evolution of the SCPS. The age of crude oils (28.3 ± 5.5 Ma) broadly agrees with petroleum generation models proposed by PEMEX.

Integrated sequence stratigraphy and geochemistry has significantly improved our knowledge of the formation and distribution of early and late diagenetic products in North American Mississippian carbonates. Deposition of the Madison Limestone occurred in concert with a major perturbation to the global C-pool, the timing of which was constrained by comparing secular variations in the delta13C values from the Madison Limestone with limited biostratigraphy. These early constraints were then improved by peak matching of 87Sr/86Sr values from this study with European brachiopod 87Sr/86Sr. The secular variations in the delta13C values were then applied as a chronostratigraphic tool to outcrops and subsurface core. As a result, our sequence stratigraphic interpretations and knowledge regarding lateral facies variability in carbonate rocks is significantly improved. Geographic variability in the magnitude of the delta13C values is also documented along the dip-transects which suggests that marine waters experienced increasing restriction in a landward direction. These results show how local changes to the C-pool are controlled by the morphology of the depositional system which can significantly affect the original signal of the global carbon pool. The geographic variability in the delta13C and delta18O values from reservoir quality dolomites along the mid-to-upper Madison ramp suggest they also precipitated from a restricted water mass with increased salinity, temperature and alkalinity which in turn, were responsible for the distribution of massive quantities of strataform dolomite deposited during the continental transgression at the beginning of the Mississippian. Trace element and 87Sr/86Sr values from strataform dolomite suggest initial formation from Mississippian seawater and slight resetting during shallow burial diagenesis. Petrography indicates that the formation of this dolomite ceased in the shallow burial environment, between the Mississippian and Permian. These dolomites are cross-cut by comparatively small volumes of geothermal-hydrothermal dolomite associated with Laramide-age breccias and fractures. Tectonic-hydrothermal activity associated with the Laramide Orogeny was responsible for late stage calcite cemented fractures and breccias which cross-cut all carbonate rocks discussed in this thesis. Radiogenic 87Sr/86Sr, depleted delta18O and enriched delta13C values and the hottest fluid inclusions measured in this study suggest the late stage calcite formed in the hydrothermal environment and under the most open-system and water-dominated conditions. Tectonic-diagenesis is ultimately responsible for establishing vertical barriers in the otherwise porous and permeable strataform dolomites.

The geochemical analysis of bioapatite in vertebrate skeletal tissues is an important tool used to obtain ecological information from fossil animals. An important consideration when conducting stable isotope and trace element analyses is obtaining biogenic information that has been unaffected by diagenetic processes. A two-step pretreatment procedure is commonly used remove diagenetically altered material by removing organic material, via an oxidation reaction with H2O2 or NaOCl, and secondary carbonate, via dissolution in dilute acetic acid, from bioapatite. While much work has been done to determine the efficacy of the pretreatment process, little research has been conducted to determine the potential effects of this process on the oxygen isotope composition of enamel bioapatite. A comparison between δ18O values of fossil enamel treated with 18O-depleted (δ18O = -10.0 / V-SMOW) and 18O-enriched solutions (δ18O = +16.4 / V-SMOW). On average, samples treated with 18O-enriched solutions had δ18O values at least 0.4 / V-PDB more positive than samples treated with 18O-depleted solutions. These results suggest that the isotopic composition of solutions used in the pretreatment process can significantly affect the δ18O values of fossil enamel prior to isotopic analysis. Diagenetic alteration can potentially be assessed using the linear relationship between δ18O values of the carbonate and phosphate components of bioapatite, as any deviation from a slope of 1 suggests alteration. Comparing the relationship between δ18Op and δ18Oc for fossil mammals from the Hadar Formation suggests that this method is successful at identifying samples that are significantly different from the remaining samples due to diagenetic alteration. The relationship between δ18Oc and δ18Op for the majority of sampled fossils from the Hadar Formation has a slope very close to 1 with an average offset, and apparent fractionation factor, between δ18Oc and δ18Op consistent with modern mammals. Therefore, it is likely that many of the fossil mammals sampled from the Hadar Formation retain in vivo δ18O values relating to the δ18O value of the water they consumed. The reliability of paleodietary reconstructions using trace element ratios (notably Sr/Ca and Ba/Ca) is strongly dependent on the preservation of biogenic trace element concentrations. Although most trace element ratio research relies on bone bioapatite, enamel has a better preservation potential and may successfully preserve biogenic trace element relationships. An analysis of Sr/Ca, Ba/Ca, and Zn/Ca ratios indicates that, despite rare earth element concentrations greater than the 1ppm observed in modern enamel, mammals from the Hadar and Busidima formations potentially reflect feeding strategies observed in modern counterparts, i.e. grazers have higher Sr/Ca and Ba/Ca ratios than browsers and omnivores

The work presented in this dissertation explores the nature of agro-pastoral strategies developed by Neolithic farmers as a way to understand how early food production was inter-twined with environmental and socio-economic opportunities and constraints. Towards this end, a multi-isotope approach is used to address questions of scale and intensity of crop cultivation and animal management at the archaeological sites of Kouphovouno, southern Greece, Makriyalos, northern Greece, and Çatalhöyük, south-central Turkey. Measurements of stable carbon, nitrogen, oxygen and strontium isotope values of carbonized plant remains, human and animal bone collagen and animal tooth enamel are used to examine the similarities and differences in the types of treatments that individual species of plants and animals received during the agricultural cycle at the distinct locations. The results show that farmers at the three sites developed variable methods for exploiting the arable and pastoral landscape and catering to their economic and culinary needs. The discussion considers the implications of these findings to our understanding of the complexity and adaptability of early farming systems.

Regions of surface water and groundwater exchange are major sites for the transfer and transformation of solutes and nutrients between stream and subsurface environments. Conventional stream and groundwater exchange investigations are limited by methodologies that require intensive field investigations and/or the set-up of expensive infrastructure. These difficulties are exacerbated where hydraulic gradients are very low and stream discharge highly variable. This thesis uses a suite of environmental tracers (Cl-, Rn-222, H-2 & O-18, Sr-87/Sr-86) to characterise the extent of stream and groundwater exchange between a sand bed stream and adjacent alluvial aquifer in a subtropical catchment (the Wollombi Brook) of eastern Australia. The aims were to identify sources and relative contributions of different sources of groundwater to stream discharge and specifically to improve the methodology of using Rn-222 to obtain quantitative estimate of groundwater fluxes. The sensitivity of the Rn-222 technique for identifying groundwater discharge based on the Rn-222 concentration in stream water was improved via an iterative numerical approach to account for Rn-222 loss from stream water via turbulent gas exchange and radioactive decay. Optimal distances between stream sampling points for defining the magnitude of groundwater discharge to stream flow based on Rn-222 concentrations in stream water is a function of average stream velocity and water depth. The maximum allowable distance between sampling points for determining the magnitude of groundwater discharge to the Wollombi Brook was 2 km. This work showed that groundwater discharged to all reaches of the Wollombi Brook during baseflow and flood recession conditions. Alluvial groundwater contributed less than 30% of water to stream flow in the mid Wollombi Brook catchment. Dilution of steady-state Rn-222 concentrations measured in transects from the stream to the alluvial sediments showed that significant surface water and groundwater exchange occurs even when gradients between surface water and groundwater are low. Lateral stream water influx to the adjacent alluvial aquifer was more extensive in the lowland areas of the Wollombi Catchment during low flow than flood recession conditions. Extensive stream water influx to the adjacent alluvial aquifer occurs contrary to the net direction of surface water and groundwater flux (as indicated by hydraulic gradients toward the stream channel). The rate of stream and groundwater exchange within the adjacent alluvial aquifer appears to be greatest during baseflow conditions. Fresh alluvial groundwater appeared to provide a buffer against higher salinity regional groundwater discharge to the alluvial aquifer in some reaches of the Wollombi Brook catchment. Pumping of the alluvial aquifer and diversions of surface water may jeopardise the water quality and volume of the alluvial aquifer and induce water flow from the regional aquifer toward the stream, potentially salinising the fresh alluvial aquifer and subsequently the stream. The change in the Cl- concentration and the variation in slope of the deuterium � oxygen-18 line between consecutive stream sampling points could be used to differentiate between regional and alluvial groundwater discharge to stream flow. Incorporating this information with three-component end-member mixing using [Sr2+] and Sr-87/Sr-86 showed that stream and alluvial groundwater exchange within the stream channel was highest in the lowland floodplains during low flow conditions. The least stream and alluvial groundwater exchange occurred in the low streambed gradient mid reaches of the Wollombi Brook regardless of stream stage. The greatest difference in the degree of stream and alluvial groundwater exchange between high and low stream stages occurred in the lowland floodplains of the Wollombi Brook.

The importance of marine versus terrestrial foods in prehistoric Pacific and New Zealand diets, and the adaptation of the Polynesian diet to new enviroments, is examined through the analysis of the ratios in human bone of the stable isotopes of carbon, nitrogen and sulphur. In particular, this study seeks to obtain quantitative information which could provide answers to five main questions, relating to the subsistence focus of the early Lapita colonists in the Pacific, the significance of suger cane in the diets of early Pacific populations, the proportions of reef versus open ocean and terrestrial versus marine foods in these diets, and the identification of populations with pronounced marine or pronounced terrestrial diets. One hundred and nineteen samples of human bone from 13 sites throughtout the Pacific and New Zealand were processed. Nitrogen values were obtained directly from bone powder, while carbon values were determined from collagen produced by digesting bone powder in phosphoric acid. Sulphur evaluations were determined from a BaSo⁴ precipitate, produced after combustion of the collagen samples in a Parr bomb. Interpretation of results is approached from a comparative point of view, which enables the proportions of marine and terrestrial foods in the diets of each study group to be assessed in relation to the diets of all the other groups. Additional information on the composition of the diets is gained by comparing the stable isotope values obtained in this study with published values of other human populations, and of marine and terrrestrial plants and animals. The potential of stable isotope analysis to identify the composition of prehistoric New Zealand and Pacific diets is confirmed. A unique marine adaptation is revealed from the analysis of the Chatham Islands Moriori who appear to have focused almost exclusively on marine resources. In contrast, a highly terrestrial diet is suggested for groups from Nebira in Papua New Guinea and Lake Rotoiti in New Zealand.

The Avar were nomadic people from Central Asia who migrated into the Carpathian Basin in Central-Eastern Europe during the mid to late Migration Period (AD 568 - 895). Archaeological evaluation of grave goods and documentation of mortuary practices have been the primary means of understanding the Avar. However, this approach has largely neglected skeletal and biochemical analysis, in particular as these approaches relate to the biological variation, ancestry, and dietary patterns of the Avar. There remains debate as to whether disparities existed among the socially stratified Avar population of ancient Hungary. It is argued by some that these disparities existed and were the result of differential access to nutritional resources. This hypothesis was tested using the unique properties of isotopes and their chemical signatures. In so doing, the qualitative work on the grave goods was augmented by an additional, quantifiable line of evidence. To investigate social stratification among the Avar population, the techniques of chemical multi-isotope and osteological analysis were employed. Multi-isotopic analyses can be done on stable isotopes (carbon, nitrogen, and oxygen) and on the heavy isotopes (strontium and lead). The particular stable isotopes examined were carbon (δ13C), nitrogen (δ15 N), and oxygen (δ18O). The heavy isotopes analyzed were strontium (87Sr/86Sr) and lead (206Pb/204Pb). Stable isotope analysis as well as ratio analysis of the heavy isotopes strontium (87Sr/86Sr) and lead (206Pb/204Pb) are well-established analytical chemistry methods for examining diverse aspects of diet and mobility through specific geographic regions. The analysis was performed on samples derived from well-preserved tooth enamel and bones. Reconstructing migration and dietary patterns at the Sajópetri cemetery site has helped estimate variability among social groups and between sexes in this population at the time of the Migration Period. Results of the heavy isotope analysis revealed that the Avar population were non-locals to the region, and the stable isotope analysis demonstrated that there was little variation between social groups with slightly higher variation between sexes. This research provides an empirical and analytical framework for further research into migration patterns and social class dynamics of late prehistoric Hungry. This study also adds existing research possibilities to the on-going biogeochemical studies conducted throughout Europe.

The focus of this work is magma-crust interaction processes and associated crustal volatile release in subduction zone volcanoes, drawing on rock, mineral, and gas geochemistry as well as experimental petrology. Understanding the multitude of differentiation processes that modify an original magma during ascent to the surface is vital to unravel the contributions of the various sources that contribute to the final magmas erupted at volcanoes. In particular, magma-crust interaction (MCI) processes have been investigated at a variety of scales, from a local scale in the Vesuvius, Merapi, and Kelut studies, to a regional scale, in the Java to Bali segment of the Sunda Arc.  The role of crustal influences is still not well constrained in subduction systems, particulary in terms of the compositional impact of direct magma crust interplay. To address this shortcoming, we studied marble and calc-silicate (skarn) xenoliths, and used high resolution short timescale experimental petrology at Vesuvius volcano. The marbles and calc-silicates help to identify different mechanisms of magma-carbonate and magma-xenolith interaction, and the subsequent effects of volatile release on potential eruptive behaviour, while sequential short-duration experiments simulate the actual processes of carbonate assimilation employing natural materials and controlled magmatic conditions. The experiments highlight the efficiency of carbonate assimilation and associated carbonate-derived CO2 liberated over short timescales. The findings at Merapi and Kelut demonstrate a complex magmatic plumbing system underneath these volcanoes with magma residing at different depths, spanning from the mantle-crust boundary to the upper crust. The erupted products and volcanic gas emissions enable us to shed light on MCI-processes and associated volatile release in these systems. The knowledge gained from studying individual volcanoes (e.g., Merapi and Kelut) is then tested on a regional scale and applied to the entire Java and Bali arc segment. An attempt is presented to distinguish the extent of source versus crustal influences and establish a quantitative model of late stage crustal influence in this arc segment. This thesis therefore hopes to contribute to our knowledge of magma genesis and magma-crust interaction (MCI) processes that likely operate in subduction zone systems worldwide.

This work focuses on crustal interaction in magmatic systems, drawing on experimental petrology and elemental and isotope geochemistry. Various magma-chamber processes such as magma-mixing, fractional crystallisation and magma-crust interaction are explored throughout the papers comprising the thesis. Emphasis is placed on gaining insights into the extent of crustal contamination in ocean island magmas from the Canary Islands and the processes of magma-crust interaction observed both in nature and in experiments. This research underscores that the compositions of ocean island magmas, even primitive types which are classically used as probes of the mantle, are susceptible to modification by crustal contamination. The principal mechanisms of contamination identified from work on both Tenerife and Gran Canaria (Canary Islands) are assimilation and partial melting of the pre-existing island edifice and intercalated sediments by newly arriving magma (i.e. “island recycling”). The information that we can gain from studying solidified magma and entrained crustal xenoliths concerning the rates and mechanisms of crustal assimilation is, however, limited. To address this shortcoming, a series of time-variable crustal carbonate assimilation experiments were carried out at magmatic pressure and temperature using natural materials from Merapi volcano, Indonesia. A temporally constrained reaction series of carbonate assimilation in magma has hence been constructed. The experiments were analysed using in-situ techniques to observe the progressive textural, elemental, and isotopic evolution of magma-carbonate interaction. Crucially, carbonate assimilation was found to liberate voluminous crustally-derived CO2 on a timescale of only seconds to minutes in the experiments. This points to the role of rapid crustal degassing in volcanic volatile budgets, and, pertinently, in magnifying hazardous volcanic behaviour. This thesis, therefore, delivers detailed insights into the processes of magma-crust interaction from experiments and geochemistry. The outcomes confirm that crustal processes are significant factors in both, i) ocean island magma genesis, and ii) magma differentiation towards compositions with greater explosive potential which can, in turn, manifest as hazardous volcanism.
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 707

Entre 2003 et 2010, dans la région centrale nommée X de la catacombe des Saints Pierre-et-Marcellin à Rome, a été découvert et en partie fouillé un ensemble de sépultures plurielles inédites (Ier-IIIe s. ap. J.-C.) contenant plusieurs centaines d’individus, lesquels ont été inhumés selon des pratiques funéraires singulières à la suite d’un épisode de surmortalité de nature probablement épidémique. Pour appréhender l’histoire de vie (alimentation et mobilité) de ces défunts et rediscuter sur la base d’éléments nouveaux certaines hypothèses préalablement établies, nous avons mené dans le cadre de ce travail une approche archéo-biogéochimique multi-proxy (14C, δ13C, δ15N, δ18O et 87Sr/86Sr) et multi-tissulaire (émail, os, cheveu) sur un échantillon de 130 individus issus de six différentes chambres. Nous avons dans un premier temps vérifié l’intégrité biochimique et isotopique des fractions minérales (phases carbonatées) et organiques (phases collagénique et kératinique) des échantillons à partir d’indicateurs classiques mesurés en routine (%Col, %C, %N, C/N, PCO2 et PCO2/Masse) et par spectroscopie IRTF (IRSF, CO3/PO4 et AmideI/PO4) et par une approche innovante consistant en des datations 14C sur couples collagène-apatite pour valider le signal isotopique des fractions minérales. Nos résultats mettent en évidence des différences extrêmes de préservation de toutes les phases. La trajectoire diagénétique des échantillons n’est toutefois pas aléatoire mais dépendante des conditions environnementales et taphonomiques différant entre les petites et les grandes chambres. En outre, nous avons pu démontrer qu’en dépit de fortes recristallisations et d’échanges isotopiques avec l’environnement sépulcral, les phases carbonatées possèdent un signal isotopique biogénique non altéré. Nous avons dans un second temps reconstruit les régimes alimentaires des individus en nous appuyant sur des référentiels de comparaisons robustes ainsi que divers modèles interprétatifs (mono-proxys versus multi-proxys ; qualitatifs versus quantitatifs), lesquels ont été dans certains cas adaptés au besoin de notre étude. D’une façon générale, nos résultats montrent que l’essentiel des individus a eu accès à un régime alimentaire type fondé sur la triade Céréales C3/Viande C3/Poisson marin. Ce régime alimentaire type n’est toutefois pas exclusif, certains individus (n = 13) ayant consommé de façon occasionnelle d’autres catégories de ressources tels que du poisson dulcicole ou des céréales C4. Nos résultats révèlent que les changements d’alimentation au cours de la vie sont relativement limités. Par ailleurs, cette population se singularise sur un plan strictement alimentaire au regard des autres populations contemporaines romaines pour lesquelles des valeurs isotopiques sont publiées. Nous avons dans un troisième temps étudié les schémas de mobilité des individus en nous fondant sur une approche rigoureuse de nos données et sur des référentiels de comparaison les plus exhaustifs possible ainsi qu’en tenant compte de biais ordinairement éludés (faits culturels, influence du climat et erreurs associées aux équations de conversion). Nos résultats mettent en lumière qu’a minima 23 % (n = 30) des individus étudiés sont migrants. Ces derniers ne se distinguent toutefois pas de par leur alimentation des résidents romains. Nous avons pu montrer en outre que ces migrants ont eu des trajectoires de vie complexes et hétérogènes et que trois schémas de mobilité distincts les caractérisent. Notre population ne se différencie pas en termes de taux de migrants des autres populations romaines pour lesquelles des données isotopiques sont disponibles. Elle se distingue en revanche par son cosmopolitisme avec des origines pour les migrants des plus diverses : Europe, Afrique, Arabie et Asie mineure [...]
An assembly of unpublished complex plural burials (1st-3rd cent. AD.) was discovered and partially excavated, between 2003 and 2010 in the central region called X of the catacomb of Saints Peter and Marcellinus in Rome. It contains several hundred individuals which were buried according to uncommon funeral practices following a mortality episode of likely epidemic nature. To understand the life history (diet and mobility patterns) of these deceased and to discuss again certain assumptions previously established on the basis of new evidences, we have as part of this work conducted an archaeo-biogeochemical multi-proxy (14C, δ13C, δ15N, δ18O et 87Sr/86Sr) and multi-tissue (enamel, bones, hair) approach on a sub-sample of 130 individuals coming from six different chambers. At the outset, we tested the biochemical and isotopic integrity of mineral (carbonate phases) and organic fractions (collagen and keratin phases) samples from conventional indicators measured in routine (%Col, %C, %N, C/N, PCO2 et PCO2/Mass), by FTIR spectroscopy (IRSF, CO3/PO4 and AmideI/PO4) and by an innovative approach consisting of 14C dating on collagen-apatite to validate the isotopic signal of mineral fractions. Our results highlight extreme differences of preservation of all phases. Diagenetic trajectory of samples is however not random but dependent on environmental and taphonomical conditions which differ between small and large chambers. Furthermore, we have been able to demonstrate that, despite strong recrystallization and isotopic exchanges with the sepulchral environment, carbonated phases have an unaltered biogenic isotopic signal. Secondly, we rebuilt the diets of individuals based on robust comparisons repositories and various interpretative models (mono-proxy versus multi-proxies; qualitative versus quantitative) which were, in some cases, adapted to the needs of our study. In general, our results show that most of the individuals had access to such a type diet based on the triad Cereals C3/Meat C3/Marine fish. This type diet would however not be exclusive, some individuals (n = 13) would have indeed occasionally consumed other resources such as freshwater fish or C4 cereals. Our results indicate that changes of diet during the life history are relatively limited. Besides, with regard to consumed food, this population is distinguished from other contemporary Roman populations for whom isotopic values are published. In the third place, we studied individual’s mobility patterns based on a rigorous approach to our data and on a comparison of the most comprehensive repositories as possible with taking into account the bias usually evaded (cultural facts, influence of climate and errors associated with conversion equations). Our results highlight that a minimum of 23% (n = 30) of the studied individuals are migrants. These, however, are not distinguished from Roman residents through their diet. We were able to show further that these migrants had complex and heterogeneous trajectories during their life within three distinct mobility patterns characterizing them. In terms of migrant’s rates, our population does not differ from other Roman populations for which the isotopic data are available. It differs however by its cosmopolitanism with origins for more diverse migrants: Europe, Africa, Arabia and Asia Minor [...]
Tra il 2003 e il 2010, nella regione centrale chiamata X della catacomba dei Santi Pietro e Marcellino a Roma, è stato scoperto e parzialmente scavato un insieme di sepolture plurime inedite (I-III sec. D.C.) contenente diverse centinaia di individui, i quali sono stati inumati secondo le pratiche funerarie singolari in seguito ad un episodio di sovramortalità di natura probabilmente epidemica. Per comprendere la storia di vita (alimentazione e mobilità) di questi defunti e ridiscutere, sulla base di nuovi elementi, alcune ipotesi precedentemente formulate, abbiamo condotto, nel quadro di questo lavoro, un approccio archeo-biogeochimico multi-proxys (14C, δ13C, δ15N, δ18O e 87Sr/86Sr) e multi-tessuto (smalto, ossa, capelli) su un campione di 130 individui da sei stanze diverse. Abbiamo inizialmente verificato l'integrità biochimica e isotopica delle frazioni minerali (fasi carbonatiche) ed organiche (fasi collageniche e cheratiniche) dei campioni provenienti da indicatori classici misurati in routine (%Col, %C, %N, C/N, PCO2 e PCO2/Massa) e per spettroscopia FTIR (IRSF, CO3/PO4 e AmmideI/PO4) ed un approccio innovativo costituito da datazione 14C su coppie collagene-apatite per validare il segnale isotopico delle frazioni minerali. I nostri risultati mettono in evidenza delle differenze estreme di preservazione di tutte le fasi. La traiettoria diagenetica dei campioni non è però aleatoria, ma dipendente dalle condizioni ambientali e tafonomiche che differiscono tra camere piccole e grandi. Inoltre, abbiamo potuto dimostrare che nonostante delle forti ricristallizzazioni e degli scambi isotopici con l'ambiente sepolcrale, le fasi carbonatiche hanno un segnale isotopico biogenetico inalterato. Abbiamo in un secondo tempo ricostruito i regimi alimentari degli individui basandoci su riferimenti di confronto robusti e vari modelli interpretativi (mono-proxys versus multi-proxys, qualitativi versus quantitativi), i quali sono stati in alcuni casi, adattati alle esigenze del nostro studio. In generale, i nostri risultati mostrano che la maggior parte degli individui ha avuto accesso ad un regime alimentare tipo basato sulla triade Cereali C3/Carne C3/Pesci marini. Questo regime alimentare non è tuttavia esclusivo, avendo certi individui (n = 13) consumato casualmente altre categorie di risorse come il pesce dulciacquicolo o dei cereali C4. I nostri risultati indicano che i cambiamenti di alimentazione nel corso della vita sono relativamente limitati. Inoltre, questa popolazione si distingue da un piano strettamente alimentare rispetto alle altre popolazioni contemporanee romane per le quali dei valori isotopici sono pubblicati. Abbiamo in un terzo tempo studiato gli schemi di mobilità degli individui basandoci su un approccio rigoroso dei nostri dati e su riferimenti di confronto i più esaustivi possibile, e anche tenendo conto di punti di vista solitamente elusi (fatti culturali, influenza del clima e errori associati alle equazioni di conversione). I nostri risultati mettono in luce che a minima 23% (n = 30) degli individui studiati sono migranti. Questi ultimi, tuttavia, non si distinguono per la loro alimentazione dai residenti romani. Abbiamo potuto mostrare, inoltre, che questi migranti hanno avuto percorsi di vita complessi ed eterogenei e che tre schemi di mobilità distinti li caratterizzano. Nostra popolazione non si differenzia in termini di tasso di migranti da altre popolazioni romane per le quali sono disponibili dei dati isotopici. Essa si distingue tuttavia per il suo cosmopolitismo con delle origini per i migranti delle più diverse: Europa, Africa, Arabia e Asia Minore [...]

Ce manuscrit présente les premiers résultats d'études élémentaires et isotopiques du Zn, du Sr et du Pb, réalisées dans les principaux types d'échantillons liés aux gaz volcaniques (gaz, sublimés, eaux thermales, roches), ainsi que deux nouvelles méthodologies d'échantillonnage des émanations volcaniques. Les variations isotopiques du Zn observées au Merapi suggèrent que les processus de changement de phase (fluides/solides) peuvent provoquer des fractionnements isotopiques significatifs des éléments trace métalliques. L'étude couplée Sr/Pb réalisée à Vulcano indique que les compositions en éléments trace métalliques des fumerolles et des eaux thermales sont influencées par les sources naturelles et anthropiques. Ce travail a aussi permis la mise au point de nouvelles méthodologies d'échantillonnage et d'analyse des gaz et des panaches volcaniques, permettant d'accéder à la composition chimique complète de ces manifestations gazeuses de manière simple et efficace.

The Station Creek Igneous Complex (SCIC) is one of the largest Middle-Late Triassic plutonic bodies in the northern New England Orogen of Eastern Australia. The igneous complex comprises of five plutons - the Woonga Granodiorite (237 Ma), Woolooga Granodiorite (234 Ma), Rush Creek Granodiorites (231 Ma) and Gibraltar Quartz Monzodiorite and Mount Mucki Diorite (227 Ma respectively), emplaced as high-level or epizonal bodies within the Devonian-Carboniferous subduction complex that resulted from a westward subduction along the east Australian margin. Composition of the SCIC ranges from monzogabbro to monzogranite, and includes diorite, monzodiorite, quartz monzodiorite and granodiorite. The SCIC has the typical I-type granitoid mineralogy, geochemistry and isotopic compositions. Its geochemistry is characteristics of continental arc magma, and has a depleted-upper mantle signature with up to 14 wt% supracrustal components (87Sr/86Srinitial = 0.70312 to 0.70391; Nd = +1.35 to +4.9; high CaO, Sr, MgO; and low Ni, Cr, Ba, Rb, Zr, Nb, Ga and Y). The SCIC (SiO2 47%-76%) has similar Nd and Sr isotopic values to island-arc and continentalised island-arc basalts, which suggests major involvement of upper mantle sourced melts in its petrogenesis. SCIC comprises of two geochemical groups - the Woolooga-Rush Greek Granodiorite group (W-RC) and the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group (MMD-GQM). The W-RC Group is high-potassium, calc-alkalic and metaluminous, whereas the MMD-GQM Group is medium to high potassium, transitional calc-alkalic to tholeiitic and metaluminous. The two geochemical groups of the SCIC magmas are generated from at least two distinct sources - an isotopically evolved Neoproterozoic mantle-derived source with greater supracrustal component (10-14 wt%), and an isotopically primitive mafic source with upper mantle affinity. Petrogenetic modeling using both major and trace elements established that the variations within respective geochemical group resulted from fractional crystallisation of clinopyroxene, amphibole and plagioclase from mafic magma, and late fractionation of alkalic and albitic plagioclase in the more evolved magma. Volcanic rocks associated with SCIC are the North Arm Volcanics (232 Ma), and the Neara Volcanics (241-242 Ma) of the Toogoolawah Group. The major and trace element geochemistry of the North Arm Volcanics is similar to the SCIC, suggesting possible co-magmatic relationship between the SCIC and the volcanic rock. The age of the North Arm Volcanics matches the age of the fractionated Rush Creek Granodiorite, and xenoliths of the pluton are found within epiclastic flows of the volcanic unit. The Neara Volcanics (87Sr/86Sr= 0.70152-0.70330, 143Nd/144Nd = 0.51253-0.51259) differs isotopically from the SCIC, indicating a source region within the HIMU mantle reservoir (commonly associated with contaminated upper mantle by altered oceanic crust). The Neara Volcanics is not co-magmatic to the SCIC and is derived from partial melting upper-mantle with additional components from the subducting oceanic plate. The high levels emplacement of an isotopically primitive mantle-derived magma of the SCIC suggest periods of extension during the waning stage of convergence associated with the Hunter Bowen Orogeny in the northern New England Orogen. The geochemical change between 237 to 227 Ma from a depleted-mantle source with diminishing crustal components, to depleted-mantle fractionate, reflects a fundamental change in the source region that can be related to the tectonic styles. The decreasing amount of supracrustal component suggests either thinning of the subduction complex due to crustal attenuation, leading to the late Triassic extension that enables mantle melts to reach subcrustal levels.

The Station Creek Igneous Complex (SCIC) is one of the largest Middle-Late Triassic plutonic bodies in the northern New England Orogen of Eastern Australia. The igneous complex comprises of five plutons - the Woonga Granodiorite (237 Ma), Woolooga Granodiorite (234 Ma), Rush Creek Granodiorites (231 Ma) and Gibraltar Quartz Monzodiorite and Mount Mucki Diorite (227 Ma respectively), emplaced as high-level or epizonal bodies within the Devonian-Carboniferous subduction complex that resulted from a westward subduction along the east Australian margin. Composition of the SCIC ranges from monzogabbro to monzogranite, and includes diorite, monzodiorite, quartz monzodiorite and granodiorite. The SCIC has the typical I-type granitoid mineralogy, geochemistry and isotopic compositions. Its geochemistry is characteristics of continental arc magma, and has a depleted-upper mantle signature with up to 14 wt% supracrustal components (87Sr/86Srinitial = 0.70312 to 0.70391; Nd = +1.35 to +4.9; high CaO, Sr, MgO; and low Ni, Cr, Ba, Rb, Zr, Nb, Ga and Y). The SCIC (SiO2 47%-76%) has similar Nd and Sr isotopic values to island-arc and continentalised island-arc basalts, which suggests major involvement of upper mantle sourced melts in its petrogenesis. SCIC comprises of two geochemical groups - the Woolooga-Rush Greek Granodiorite group (W-RC) and the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group (MMD-GQM). The W-RC Group is high-potassium, calc-alkalic and metaluminous, whereas the MMD-GQM Group is medium to high potassium, transitional calc-alkalic to tholeiitic and metaluminous. The two geochemical groups of the SCIC magmas are generated from at least two distinct sources - an isotopically evolved Neoproterozoic mantle-derived source with greater supracrustal component (10-14 wt%), and an isotopically primitive mafic source with upper mantle affinity. Petrogenetic modeling using both major and trace elements established that the variations within respective geochemical group resulted from fractional crystallisation of clinopyroxene, amphibole and plagioclase from mafic magma, and late fractionation of alkalic and albitic plagioclase in the more evolved magma. Volcanic rocks associated with SCIC are the North Arm Volcanics (232 Ma), and the Neara Volcanics (241-242 Ma) of the Toogoolawah Group. The major and trace element geochemistry of the North Arm Volcanics is similar to the SCIC, suggesting possible co-magmatic relationship between the SCIC and the volcanic rock. The age of the North Arm Volcanics matches the age of the fractionated Rush Creek Granodiorite, and xenoliths of the pluton are found within epiclastic flows of the volcanic unit. The Neara Volcanics (87Sr/86Sr= 0.70152-0.70330, 143Nd/144Nd = 0.51253-0.51259) differs isotopically from the SCIC, indicating a source region within the HIMU mantle reservoir (commonly associated with contaminated upper mantle by altered oceanic crust). The Neara Volcanics is not co-magmatic to the SCIC and is derived from partial melting upper-mantle with additional components from the subducting oceanic plate. The high levels emplacement of an isotopically primitive mantle-derived magma of the SCIC suggest periods of extension during the waning stage of convergence associated with the Hunter Bowen Orogeny in the northern New England Orogen. The geochemical change between 237 to 227 Ma from a depleted-mantle source with diminishing crustal components, to depleted-mantle fractionate, reflects a fundamental change in the source region that can be related to the tectonic styles. The decreasing amount of supracrustal component suggests either thinning of the subduction complex due to crustal attenuation, leading to the late Triassic extension that enables mantle melts to reach subcrustal levels.

Coastal systems in semi-arid areas are characterised by complex physico-chemical processes involving mixing of marine and continental water sources as well as precipitation of evaporitic and carbonate minerals. The latter processes involving carbonate cycling also represent an important but currently poorly constrained component of the coastal carbon budget. This thesis fills important knowledge gaps in our understanding of water source mixing and local carbonate cycling in a semi-arid coastal system in South Australia – the Coorong, Lower Lakes and Murray Mouth (CLLMM) estuary, using selected alkaline earth metals (Ca and Sr) and their isotopes with the following research components: 1. Application of radiogenic Sr isotopes ((87)Sr/(86)Sr), stable Ca isotopes (δ(44/40)Ca) and elemental ratios, complemented by mineralogical analysis of top-sediment samples and geochemical (PHREEQC) modelling of carbonate saturations in the CLLMM waters to constrain the water source apportionment and local carbonate output in the Coorong lagoon. 2. Development and validation of high-precision stable Sr isotope analysis (δ(88/86)Sr) using thermal ionisation mass spectrometry (TIMS) and follow up calibration of δ(88/86)Sr in the CLLMM waters with respect to changing salinity and carbonate saturation states. 3. Application of (87)Sr/(86)Sr and δ(88/86)Sr tracers, along with elemental concentration data, to monitor seasonal variations (i.e., every 3 months) in water source mixing and carbonate dynamics (i.e., dissolution vs precipitation) in the CLLMM. 4. Reconstruction of palaeo-hydrology and salinity in the Coorong South Lagoon throughout the past ~2400 years, based on (87)Sr/(86)Sr, δ(88/86)Sr and Mg/Sr analysed in fossil bivalve shell species (Arthritica helmsi) collected from sediment cores. The above data were complemented by radiocarbon (14C) and pollen-based geochronological models. Overall, the results from the thesis showed that the modern North Lagoon waters are mainly sourced from the Southern Ocean, with transient freshwater inputs sourced from the River Murray and Lower Lakes and/or local groundwater discharge. In contrast, the hypersaline South Lagoon waters are basically highly evaporated ‘brackish waters’ with significant contribution of Sr from continental water sources. Importantly, stable Ca and Sr isotope tracers and water chemistry data indicate that the South Lagoon acts as a net sink for dissolved inorganic carbon (DIC) in the form of precipitated carbonate minerals (mostly aragonite). Both δ(44/40)Ca and δ(88/86)Sr in the CLLMM waters seem to be controlled by mass-dependent isotope fractionation, most likely related to carbonate dissolution and precipitation. Despite the current uncertainty regarding the role of local groundwater discharge on the chemistry of Coorong waters, the results indicate that an increased alkalinity supply (mainly from the Salt Creek) may locally promote CaCO3 precipitation and increase in δ(88/86)Sr of waters in the South Lagoon. Finally, the multi-proxy analysis ((87)Sr/(86)Sr, δ(88/86)Sr and Mg/Sr) of fossil shells revealed that over the past two millennia the South Lagoon waters were never purely marine but originally rather comprised brackish waters (estimated minimum salinities of ~6-23 PSU) with at least 60% contribution from continental water. Overall, the findings of this thesis improved our understanding of modern and past water source mixing and carbonate cycling in the CLLMM system and can hopefully benefit future water management strategies and plans.
Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2021

Research Doctorate - Doctor of Philosophy (PhD)
Changes in geochemical and physical properties of speleothems are considered to be accurate proxies of climate variability. However, the climate signal is modified by the internal dynamics of the whole karst system. The aim of the research was to obtain reproducible data extracted by established and non-conventional techniques from two coeval speleothems removed at Grotta Savi cave (Italy), to gain information about regional climate responses across the Last Glacial Maximum to Holocene transition. Different past hydrological regimes for the two stalagmites’ drips were reconstructed on the basis of stalagmites’ physical characteristics and this helped to disentangle the global from the local phenomena. This non-conventional approach, was applied here for the first time on fossil sample, resulting in a benchmark for interpreting the chemical proxies, and enabling assessment of calcite formation environment, hitherto not possible. The interpretation of δ¹⁸O values as reflecting past hydrology was then validated by using the Hydrology Index. The Index, developed in this study, considers two independent proxies: the Mg concentrations and the fraction of Sr uptake that is not dictated by growth rates. The method allowed recognition of a non-hydrological component encapsulated in δ¹⁸O values, then interpreted as changes of air mass provenance and rainfall seasonality. The δ¹³C was chiefly driven by temperature-dependent soil respiration rate. However, a hydrological component was also detected in the δ¹³C by using dead carbon proportion (dcp) and ⁸⁷Sr/⁸⁶Sr ratios. Increases of ⁸⁷Sr/⁸⁶Sr ratios suggest increases of aeolian dust deflated from proximal subalpine periglacial regions facilitated by vegetation-cover reduction, soil destabilisation and windier conditions, which in turn enhanced drier conditions. Although, the dcp trend was likely related to a local, faster, soil organic matter turnover, enhanced by warmer conditions, episodes of high dcp values were possibly hydrologically induced, as a result of wetter conditions. Furthermore, the Hydrology Index and δ¹³C signal allowed reconstructing that wet conditions occurred during climate cooling, an improvement relative to the state of the art of δ¹³C interpretation, where more commonly wet conditions occurs during warming. The comparison of δ¹³C trend of Savi with another stalagmite with similar physical characteristics, but from a cave (Sofular) located in Turkey, revealed a common trend despite the impact of the last glaciation having been drastic at Savi (no speleothem growth). Such δ¹³C similarity could be related to global phenomena and point to an intriguing possibility, which needs future testing, that speleothems may encode information of the C cycle, similar to soil carbonates. The palaeoclimate interpretation extracted from the Savi records between 15 to 9 ka indicates that the Younger Dryas (YD) was a dramatic climate reversal. In the northern Adriatic, the YD is characterised by high hydrological variability, strong winds and a cooling, which resulted in a decrease of vegetation cover and increase of soil erosion. The wind regime was possibly orographically induced, with the Alps acting as a barrier, deviating westerly winds and causing increased windiness in the northern Adriatic region. The Savi records reveal a significant Early Holocene anomaly (10.4 ka), whose drier and colder conditions were probably amplified by a local synoptic framework.

This project provides an up to date study of the various types and occurrences of gold-(base metal) mineralisation in the Adelaide Fold Belt, South Australia. The Adelaide Fold Belt comprises Neoproterozoic to Cambrian sediments and igneous rocks and Mesoproterozoic basement inliers deformed and metamorphosed during the Delamerian Orogeny between 520Ma and 490 Ma. A number of small primary gold-(base metal) mineralisations are known in the Fold Belt which have produced about 250.000 oz of gold since the middle of the 19th century. This study investigates the geological setting, the mineralogy, geochemistry, fluid characteristics, stable and radiogenic isotopes as well as the timing of these mineralisation in relation to the Delamerian Orogeny. Gold mineralisation in the Adelaide Fold Belt are dominantly sediment-hosted, structurally controlled mineralisation in host-rocks that underwent greenschist- to amphibolite facies metamorphism during the Delamerian Orogeny. The majority of mineralisations is hosted by a restricted section of the Neoproterozoic Adelaidean strata, the lower Umberatana Group. Gold in the investigated mineralisation is usually associated with base metals (Cu and, or Pb-Zn-Cd-Ag). Fluid inclusion studies show that mineralising fluids have moderate to high salinities. Fluid inclusion studies were combined with Titanium in Quartz geothermobarometry resulting in a T-P range of ore formation from 300℃ to 450℃ and 1.5 kbar to 5 kbar. Oxygen isotopes of hydrothermal quartz (+13.3%to +19.9%) and carbonate (+10.8%to +30.6%) indicate an metamorphic origin of fluids. Carbon isotopes of hydrothermal carbonate range from -10.2%to +1.4%and may be a result of a mixing of carbon from sedimentary carbonate and C[subscript]org. Sulphur isotope values in the investigated mineralisation range from +2%to +25%supporting a sedimentary sulphur source within the Adelaidean strata. Zn-isotope values of sphalerite from the Woodside goldfield range from -0.53%to +0.43%with the majority of values close to crustal average, indicating that most Zn from the source could be mobilised and that no fractionation took place between source and mineralisation. Pb isotopes of galena of the Woodside and Baratta mineral field are anomalous radiogenic and could represent a source within the Basement or the Adelaidean strata. Sr-isotopes of vein carbonate range from 0.710 to 0.719 and support a Sr source within the central to lower Adelaidean. Direct dating of mineralisation and the relationship of mineralisation to Delamerian igneous rocks show that mineralisation formed post-peak metamorphism in the extensional late stage of the Delamerian Orogeny or later. Most mineralisation have shown no links to magmatic activity. The general geological, structural and T-P characteristics support a classification of the investigated mineralisation as orogenic gold mineralisation but fluid chemistry and the base metal content of the mineralisation are unusual for these type of deposits. Some deposits in the central part of the Adelaide Fold Belt (Nackara Arc) also have characteristics of Telfer-style mineralisation.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2011

The Alberta Basin has been the subject of various diagenetic studies but the precise understanding of the processes behind deep burial cementation remains unclear. This study investigates late-diagenetic calcites from the Devonian Southesk-Cairn Carbonate Complex with the purpose of constraining temperature, relative timing and chemistry of the paleo-fluids involved during calcite precipitation. Two types of late-diagenetic calcites were petrographically andgeochemicallycharacterized.Whereascalcite-Iresultedfrom thermochemical sulfate reduction, calcite-II precipitated with no or little oxidized organic carbon present. As shown by the Sr isotopic signatures, some reservoirs were exposed to radiogenic Sr-bearing fluids. A slight trend of increasing fluid inclusion homogenization temperatures with depth is only seen in calcite-I, and bitumen reflectance also increases with depth following a normal burial gradient. These results, however, are not conclusive to interpret the influence of tectonically-driven fluids during deep burial.

Thesis (M.Sc.)--University of Alberta, 2010.
Title from PDF file main screen (viewed on Apr. 13, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Earth and Atmospheric Sciences, University of Alberta. Includes bibliographical references.