Tesi sul tema "Sulphur and Callcium isotopes"

La limite Crétacé-Paléogène (KPg, -66 Ma) est associée à l'une des plus grandes perturbations environnementale de l'histoire récente de la Terre. Cette crise, liée à la mise en place d'une province magmatique de premier ordre (traps du Deccan) et/ou à un impact météoritique (formation du cratère de Chixculub) se traduit entre autres par une perturbation profonde de la bioproduction carbonatée océanique. Si de nombreuses questions subsistent quant à l'importance relative de l'impact et du volcanisme dans les perturbations de la limite KPg, la modification de la composition chimique du système océan-atmosphère par l'émission d'énormes quantités d'acide sulfurique et carbonique d'origines volcaniques a probablement joué un rôle clé dans la crise Crétacé-PaléogèneDurant ce projet de thèse j'ai réalisé des enregistrements isotopiques à haute résolution des isotopes stables du soufre et du calcium à travers la transitons Crétacé-Paléogène. Ces enregistrements sont basés sur des échantillons monospécifiques de foraminifères planctoniques et benthiques issue du pacifique équatorial.Les enregistrements de δ44/40Ca benthiques et planctoniques avant et après la limite K-Pg nous ont permis de mettre en évidence une succession d'épisodes de changements de l'alcalinité océanique liés à l'augmentation de l'altération continentale et à la crise de biocalcification causée par les émissions de CO2 du volcanisme du Deccan. La compensation des carbonates par la dissolution des sédiments carbonatés, la réduction de la biocalcification et/ou l'augmentation de l'altération continentale ont dû se produire pour compenser l'excès de CO2. Par conséquence, cela a entraîné des changements rapides dans la chimie des carbonates océaniques, en combinaison avec une réduction de l'exportation de l'alcalinité de surface en réponse à la crise de biominéralisation planctonique du Paléogène précoce.L'examen de la perturbation du cycle du soufre quant lui, soutient plutôt l'idée que l'extinction de masse à travers la transition K-Pg n'est pas être associée à une expansion globale de conditions anoxique, contrairement aux différents événements d'extinction de masse du Phanérozoïque, où il existe des preuves multiples du de développement de condition anoxique associé aux perturbations du cycle du carbone. Ces conclusions est en accord avec les observations micropaléontologiques qui ne montrent pas d'extinction de masse des foraminifères benthiquesCette approche géochimique multiproxies a l'avantage de permettre donc une évaluation plus pousser de certains paramètres clés tel que la chimie des carbonates et l'anoxie océanique à travers la transition Crétacé -Paléogène permettant ainsi d'avoir un schéma global plus clair des perturbations biogéochimiques autour de cette période
The Cretaceous-Paleogene boundary (KPg, -66 Ma) is associated to one of the deepest biogeochemical cycle disruptions in Earth's recent history. The events associated to the KPg boundary include one of the strongest known oceanic calcareous bioproduction crisis and are coeval with a bolid impact (that formed the Chixculub crater) and the emplacement of a Large Igneous Province (Deccan traps). Many studies investigated the mechanism(s) triggering the environmental perturbations and many questions remain unanswered regarding the relative contribution of the volcanic event and the impact on the KPg crisis. Yet, modification of the ocean-atmosphere system composition through massive input of sulfuric and carbonic acid very likely played a key, underconstrained, role.During this thesis project, I conducted high-resolution stable sulphur and calcium isotope records across the Cretaceous-Paleogene transition. These records are based on monospecific samples of planktonic and benthic foraminifera from the equatorial Pacific.The benthic and planktonic δ44/40Ca records before and after the K-Pg boundary allowed us to demonstrate a succession of episodes of ocean alkalinity change related to the increase in continental weathering and the biocalcification crisis caused by CO2 emissions from Deccan volcanism. Carbonate compensation through dissolution of carbonate sediments, reduction of biocalcification and/or increase in continental weathering had to occur to compensate for the excess CO2. As a result, this led to rapid changes in oceanic carbonate chemistry, in combination with a reduction in the export of surface alkalinity in response to the early Paleogene planktonic biomineralisation crisisExamination of sulphur cycle disruption instead supports the idea that mass extinction through the K-Pg transition is not associated with a global expansion of anoxic conditions, in contrast to the various Phanerozoic mass extinction events, where there are multiples evidences for the development of anoxic conditions associated with carbon cycle disruption. These findings are consistent with micropalaeontological observations that show no benthic foraminiferal mass extinction.This multi-proxy geochemical approach has the advantage of allowing a more detailed assessment of key parameters such as carbonate chemistry and oceanic anoxia across the Cretaceous-Paleogene transition, thus providing a clearer global picture of biogeochemical perturbations around this time

This project focuses on two Palaeozoic mass extinction events: the Frasnian-Famennian crisis of the Late Devonian and the end-Guadalupian event of the Permian for which similar extinction mechanisms have been proposed. These have been evaluated by examining the nature of the Sr and S isotopic systems during these intervals. Proposed extinction mechanisms for the Late Devonian event include extraterrestrial impacts, rapid sea-level fluctuations, climate change eutrophication and the spread of anoxia in bottom waters. Many models invoke changes in nutrient fluxes related to proposed increases in continental weathering or hydrothermal/volcanic fluxes but these theories have not been tested on a global scale. This study attempted to address this by compiling high resolution 87Sr/86Sr ratio curves for an interval spanning the FrasnianFamennian boundary based on measurements in well-preserved conodont apatite from sections in Poland and Iowa.

Dissolved organic matter (DOM) is present in all forested catchments and can be important in binding metals, absorbing UV, and the transport of nutrients (C, N, S, P). DOM is extremely heterogeneous in time and space, making it difficult to characterize. New techniques have been developed to determine δ34S and δ18O in DOM. These techniques have been applied to samples from Harp and Plastic Lake catchments (45º23'N, 79º 08'W, 45º11'N, 78º 50'W) in order to obtain information about sources and sinks of DOM within forested catchments on the Canadian Shield. In conjunction with sulphate and DOC concentrations, this new data provides valuable insight into sulphur cycling and DOM alteration within these catchments. Data generated for δ34S-DOM and δ18O-DOM appears to be the first data reported in the literature for DOM. The inorganic (δ34S-SO42-) and organic S (δ34S-DOM) differs by environment in both catchments. The range of δ34S-SO42- is between 3. 3‰ and 10. 3‰, and the range of δ34S-DOM is from 3. 4‰ to 8. 7‰. Sulphate in the Harp Lake catchment in most samples is subject to some sort of cycling within the watershed, since δ34S-SO42- differs from precipitation. In the Harp Lake catchment, upland δ34S-SO42- is influenced by historical precipitation. The δ34S-DOM is derived from leaching and microbial activity of DOM from organic horizons in the soil. The δ34S-SO42- and δ34S-DOM of wetland streams is extremely variable, controlled by hydrology. The δ34S-SO42- provides information on oxidation-reduction dynamics in the wetland, and δ34S-DOM provides information about sources of DOS in the wetland. The δ34S-SO42- and δ34S-DOM are possibly related in Harp Lake. Mineralization of DOS as evidenced by δ34S-DOM and DOS concentrations could be a small input of SO42- into Harp Lake. It is possible δ18O-DOM could be an indicator of DOM alteration. The range of δ18O-DOM is between 8. 2‰ and 14. 4‰. The δ18O-DOM in the Harp Lake catchment is highly correlated with relative molecular weight, which has been shown to decrease with increasing alteration. Wetland streams show the largest range in δ18O-DOM, while uplands, groundwater, and Harp Lake are the least varied. The highest δ18O-DOM values are from sources of DOM such as leaf leachates (representative of forest floor litter) and wetlands. The most depleted samples are from groundwater and Harp Lake which typically contain highly altered DOM. The δ34S-DOM and δ18O-DOM can provide valuable information on sources of DOM and DOM alteration within the catchment. The δ18O-DOM could also allow the separation of autochthonous and allochthonous DOM in lakes.

Current mining operators in the Athabasca oil sands deposit of Alberta, Canada have made commitments to zero discharge of oil sands process-affected waste materials (OSPM) from the mine site and rehabilitation of mined lands to a pre-mining state. As part of aquatic reclamation efforts, experimental test sites that contain a range of OSPM (solid and liquid components) were constructed to monitor the evolution and viability of aquatic habitats used as disposal sinks for OSPM produced by mining activities. In the present study, stable isotopes of carbon, nitrogen and sulphur were used to gauge some of the potential effects of OSPM site construction methods on aquatic food webs. Carbon and nitrogen isotopic signatures of sediment, dissolved inorganic carbon, dissolved organic carbon, particulate organic matter, periphytic material, plants, plankton, aquatic invertebrates and fish were used to assess differences related to the naphthenic acid (NA) concentration in OSPM and reference sites. For statistical analyses, sites were grouped into low (0 to 4 mg/L), medium (4 to 15 mg/L) and high (> 15 mg/L) NA concentrations. There were no significant differences in food web area or food web length among the low, medium and high NA concentration sites. In most cases, sample carbon isotope analyses of low, medium and high NA concentration sites were not significantly different, suggesting food web carbon sources did not include significant contributions from OSPM materials at OSPM sites. Significant differences, however, were found in the sample nitrogen isotope signatures between low, medium and high NA concentration sites. Ammonia from OSPM is suggested to be the main contributor to δ¹⁵N enrichment.

To determine the potential effects of site construction and OSPM within experimental test sites, carbon and sulphur stable isotopes of water, plankton, aquatic invertebrates and fish were analyzed. With the exception of Chaoborus and Haliplus, all carbon isotope signatures were not significantly different in constructed and reference sites. Also with the exception of Haliplus, sulphur isotope values for aquatic organisms from constructed and reference sites were significantly different. Aquatic organisms and water samples from constructed sites built in, or close, to the boundary of Kcw clays typically had δ³⁴S < 0 ?. Coinciding with depleted δ³⁴S signatures found in these aquatic systems were elevated sulphate concentrations. The waters at experimental test sites are in direct contact with the soil materials that facilitate the accumulation of sulphates as a result of the oxidation of substrate sulphide minerals. In general the results of the study suggest that aquatic food web structure and function do not change with the introduction of OSPM. Shifts in isotopic signatures suggestive of changes in food web structure, however, do occur when site construction exposes Kcw clays in the substrate.

Les émissions volcaniques sont une source importante de soufre. Le soufre volcanique est oxydé et forme des aérosols sulfatés qui influencent le climat en absorbant et en dispersant le rayonnement solaire incident. Les émissions de soufre dans la troposphère influencent le climat local et régional, mais de grandes incertitudes subsistent en ce qui concerne l’oxydation et sa conversion en aérosols de sulfate volcanique. L’oxydation du soufre dans une vaste gamme de panaches volcaniques et l’influence des halogènes volcaniques sur la chimie du panache sont étudiées à l’aide d’un modèle de boîte chimique. Parallèlement, la composition isotopique en oxygène du sulfate volcanique, à savoir l’excès de 17-O (∆17O), est à l’étude, ce qui peut limiter les voies d’oxydation du soufre. Les résultats suggèrent qu’en présence de gouttelettes d’eau et de cendres, l’oxydation du soufre dans les panaches est principalement due à l’oxydation en phase aqueuse avec de l’O2 catalysé par des ions de métaux de transition (TMI). Les émissions d’halogènes favorisent la dominance de l’O2 /TMI en induisant des phénomènes d’appauvrissement de la couche d’ozone (ODE). En l’absence de gouttelettes d’eau, la chimie du panache est largement déterminée par la chimie hétérogène des aérosols primaires sulfatés. Les oxydants dominants dans ces panaches sont OH et H2O2. Le taux d’oxydation du soufre est considérablement réduit par rapport aux panaches contenant des gouttelettes d’eau. Les résultats montrent que les isotopes de l’oxygène dans les sulfates exercent de fortes contraintes sur l’équilibre chimique du soufre dans les panaches volcaniques et sur le rôle des halogènes volcaniques
Volcanic emissions are a major source of sulphur. Volcanic sulphur is oxidized and forms sulphate aerosols that influence the climate by absorbing and dispersing incident solar radiation. Sulphur emissions in the troposphere influence local and regional climate, but large uncertainties remain regarding oxidation and its conversion into volcanic sulphate aerosols. The oxidation of sulphur in a wide range of volcanic plumes and the influence of volcanic halogens on plume chemistry are studied using a chemical box model. At the same time, the isotopic oxygen composition of volcanic sulphate, namely the excess of 17-O (∆17O), is being explored, which can provide constraints on sulphur oxidation pathways. The results suggest that in the presence of water droplets and ash, the oxidation of sulphur in plumes is mainly due to aqueous phase oxidation with O2 catalyzed by transition metal ions (TMI). Halogen emissions promote the domi- nance of O2 /TMI by inducing ozone depletion events (ODEs). In the absence of water droplets, plume chemistry is largely determined by heterogeneous chemistry on primary sulphate aerosols. The dominant oxidants in these plumes are OH and H2O2. The oxidation rate of sulphur is significantly reduced compared to plumes containing water droplets. The results show that oxygen isotopes in sulphates provide strong constraints on the chemical balance of sulphur in volcanic plumes and on the role of volcanic halogens

This paper deals with the late Viking age/early medieval grave field in Björned, Torsåker parish, Ångermanland County in northern Sweden. The grave field in Björned is rare because it has all the signs of being Christianized before the surroundings. This awakes questions such as if the people of Björned came from another place and brought the religion with them or if someone else did that for them. To find these answers I have analysed the stable isotope ratios [delta]13C, [delta]15N and [delta]34S in human bone collagen. Through these stable isotopes we can not only see what the people consumed but also where their food had its origin. It seems like several people from the grave field had a different origin then the rest.

Large Igneous Provinces (LIPs) form during short-lived pulses of extensive magmatic activity. LIPs are known for their ability to affect global climate as well as for their Ni-Cu-PGE ore potential. A key factor that controls the intensity of the climate impact of a LIP and its ore potential is the assimilation of volatile-rich sedimentary host rocks. Magmas of the High Arctic Large Igneous Province (HALIP), exposed in the Arctic, intruded volatile-rich black shales, carbonates and evaporites in the Canadian Arctic Islands, offering a great opportunity for studying magma-sediment interaction. The purpose of this study is to test whether assimilation of sedimentary sulphide can promote sulphide immiscibility in magma and thus aid formation of Ni-Cu-PGE ore bodies. This is done by analysing sulphur isotopes in pyrite grains hosted in a HALIP dolerite sill, which was emplaced into black shale, by using Secondary Ion Mass Spectrometry (SIMS). Four dolerite samples are analysed; two coming from the lower contact margin of the sill, one from 60 cm into the sill and one sample from a basaltic vein at the upper contact margin of the sill. A total of 14 pyrite grains (n = 246 individual SIMS spot analyses) were analysed for their sulphur isotope ratios. The results of the SIMS analyses show that all analysed sulphides have highly negative δ34S values ranging from -19.5 to -5.7‰ (average δ34S = -8.2 ± 0.83‰, 2SD), which therefore differ largely from that of the primitive mantle (0 ± 1.8‰). In order to put our four analysed dolerite samples into a broader context, δ34S data of our sulphides are compared with whole-rock δ34S and δ18O data from Hare Fiord shale and dolerite samples. The δ34S values of the sulphide samples from the sill typically trend toward the negative sulphur isotope composition of the sulphides in the surrounding shale, and the shale surrounding the sill experiences a loss of 32S near the contact of the sill. This indicates that sedimentary light sulphur (32S) has been locally incorporated into the sill by the surrounding shale, resulting in negative δ34S values in the magmatic sulphides. Since sulphide immiscibility in the Hare Fiord sill was triggered by assimilation of sulphur from host rock shale, the igneous rocks of the HALIP may be prospective for Ni-Cu-PGE mineralization, though more studies are needed. Furthermore, our results suggest that incorporation of crustal sulphur increased the volatile budget of HALIP magmas, which therefore could have contributed to a deterioration of the environmental conditions during the emplacement of the HALIP.
Stora magmatiska provinser (på engelska Large Igneous Provinces, LIPs) är vulkaniska event då enorma mängder magma avsätts över en väldigt stor yta under ett, i ett geologiskt perspektiv, kort tidsspann. Dessa stora vulkaniska utbrott har väckt stort intresse då de är samtida med flera av de största massutdöendena i jordens historia, men också för att en viss typ av sulfidmalm rik på nickel, koppar och platinametaller (Ni-Cu-PGE malmer) ofta förekommer i provinsernas magmagångar och magmakammare. En viktig faktor som till stor del avgör en magmatisk provins påverkan på klimatet och potentiella malmförekomster är inkorporering av sedimentära bergarter till magman som, när de hettas upp, kan frigöra gaser rika på svavel och kol. I Kanadas arktiska öar trängde magma tillhörande den högarktiska magmatiska provinsen (HALIP) in i svart skiffer, karbonater och evaporiter, som är sedimentära bergarter rika på flyktiga ämnen. Denna magmatiska provins erbjuder därför stora möjligheter till att studera interaktionen mellan magma och sedimentära bergarter. Syftet med denna studie är att testa om inkorporering av sedimentärt svavel kan främja bildandet av sulfidsmälta i magma och därigenom bidra till bildandet av sulfidmalmer. Detta görs genom att analysera svavelisotoper i sulfidmineral i prover från en magmagång, som trängde in i en skifferformation, tillhörande den högarktiska magmatiska provinsen i norra Kanada. Genom att analysera svavelisotopkvoten (δ34S) i sulfidmineral kan man få information om huruvida svavlet i mineralen är av sedimentärt ursprung (där skiffer generellt har negativa δ34S värden) eller om svavlet har δ34S värden liknande de från manteln (som har δ34S värden runt 0‰), vilket i så fall skulle innebära att magman inte har inkorporerat sedimentärt svavel. Genom att använda masspektrometri av typen SIMS analyseras totalt 14 sulfidmineralkorn (n = 246 individuella SIMS punkter) för deras svavelisotopkvoter. Resultatet av studien visar att alla analyserade sulfidmineral har mycket negativa δ34S värden mellan -19.5 och -5.7‰ (med ett δ34S medelvärde på -8.2 ± 0.83‰, två standardavvikelser). Genom att jämföra våra δ34S värden med δ34S och δ18O värden för andra prover från både magmagången och den omgivande skiffern kunde vi se att δ34S värdena för sulfidmineralen i de yttre delarna av magmagången har liknande negativa värden som den omgivande skiffern, och att δ34S värdena för skiffern närmast magmagången är mer positiva. Detta tyder på att sedimentärt svavel i kontakten mellan magmagången och skiffern har blivit inkorporerat i magman från den omgivande skiffern. Våra resultat tyder därför på att sulfidmineralen i våra prover från magmagången bildades genom assimilering av svavel från den omgivande skiffern. Detta innebär i sin tur att den kanadensiska högarktiska magma provinsen potentiellt kan vara en källa för sulfidmalm, även om ytterligare studier behövs. Dessutom visar våra resultat att inkorporering av sedimentärt svavel förmodligen ökade de vulkaniska gaserna i magman, vilket kan ha bidragit till klimatförändringar relaterade till den vulkaniska aktiviteten av den högarktiska magmatiska provinsen.

The transport of elements by streams from headwater regions to the sea is influenced by landscape characteristics. This thesis focuses on the influence of landscape characteristics (e.g. proportion of wetland/forest coverage) on temporal and spatial variations of Fe, Mn, S and trace elements (As, Co, Pb) in streams located in northern Sweden, a boreal region characterized by coniferous forests and peat wetlands.

Water samples from a network of 15 streams revealed a different hydrogeochemistry in forested catchments compared to wetland catchments. The temporal variation was dominated by spring flood, when concentrations of Fe, Mn and trace elements increased in forested headwaters. However, in streams of wetland catchments concentrations decreased, but Pb concentrations were higher in comparison to other streams. Both Fe and Pb showed positive correlations with wetland area, while Co correlated with forest coverage. The anthropogenic contribution of As and Pb appear to be larger than the supply from natural sources.

During spring flood SO₄^2- decreased in most streams, although concentrations increased in streams of wetland catchments. Concentrations of SO₄^2- were higher in streams of forested catchments than in wetland dominated streams, the former being net exporters of S and the latter net accumulators. Isotope values of stream water SO₄^2- (δ³⁴S_SO4) were close to that of precipitation during spring flood, indicating that the major source of S is from deposition. The results show that, although emissions of anthropogenic S have been reduced, there is still a strong influence of past and current S deposition on runoff in this region.

In conclusion, wetlands are key areas for the hydrogeochemistry in this boreal landscape. The findings emphasize the importance of understanding stream water chemistry and element cycling from a landscape perspective. This may be important for predicting how boreal regions respond to environmental disturbances such as climate change.

The main aim was to investigate the provenance of Viking age antler material findings of moose and red deer from Sigtuna and from three sites on the island of Gotland in the Baltic sea. This was done by analysis of the stable isotopes of carbon, nitrogen and sulphur. Thre were never any living population of these mammals on Gotland during the Viking age. δ34S-values of sulphur from this study was compared with earlier research and by studying maps of the Swedish bedrock. The δ34S-values were more like the δ34S-value for bedrock other than European granite. These bedrocks are found in the south-east of Sweden along the coast towards Gotland. The provenance of the Sigtuna antlers could be three different areas and the material from Gotnald could come from two differente regions. A student-t test between Fröjel and Sigtuna showed no significant correlation between the two populations. A comparison within the Sigtuna material showed a possible difference between two different dated phases. This could mean that an import of antlers from other areas was made when antlers in the Sigtuna region was less available.

碩士
國立成功大學
地球科學系
105
This study involves the determination of sulphur (S) isotopes in water samples from hot springs and nearby rivers. The water samples were pre-concentrated, subjected to separation with anion exchange resin AG1-X8 and sulphur isotopic analysis was performed with a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). Concentrations of anions and cations were determined with ion chromatography (IC) and inductively coupled plasma-optical emission spectrometer (ICP-OES), respectively. Samples from western Japan were pre-defined as Na–Cl type ground water, and originated from 'fossil seawater' entrapped in the formations. The K/Cl and SO4/Cl ratios in hot spring water samples were in a range between those of rain water and sea water. The Br/Cl ratios in hot spring water samples were close to that of seawater line, and could be distinguished from river water samples. The δ34S values in most of the hot spring water samples were in the range 15.74-24.87 ‰, and this range is close to δ34S in seawater (+21 ‰). However, δ34S values in water samples from Chibben (Taiwan) and Kurama (Japan) were -1.50‰ and -3.17 ‰, respectively. The lighter sulphur isotope ratios in these two hot water spring resorts indicate the reduction of sulphate, probably by bacteria, because of domestic contamination in the groundwater system. The data on major elements and sulphur isotopes showed that the river water samples, which were collected near hot spring wells, were influenced by the hot springs. Based on the water chemistry of end members i.e., Br/Cl, Na/Cl, K/Cl, SO4/Cl and sulphur isotope signatures, most of the water samples from Eastern Taiwan were considered to be a mixture of rainwater, sulphate fluid from digenetic barite, alternating metamorphic sulphide fluid and sea water (or brine).

The Platreef has been the site of platinum mining since the 1920’s. The reef itself comprises a series of pyroxenites, gabbronorites and norites that contain xenoliths/rafts of footwall rocks. The Platreef is irregularly mineralised with PGE, Cu and Ni, and has a greater abundance of sulphides than the Merensky Reef. The main base metal sulphides within the Platreef are pyrrhotite, pyrite, pentlandite, and chalcopyrite. Extremely varied platinum group minerals occur as tellurides, bismuthotellurides, antimonides and arsenides. This study aimed to gain a clearer understanding of the formation of sulphides within the Platreef. In order to do this, cores from both the northern and southern sectors of the Platreef were sampled. A detailed study of the sulphides within these cores was conducted to identify different styles of mineralisation and their occurrences. Four different styles of mineralisation were identified: massive, net-textured, blebby and interstitial. In general, sulphides in the southern sector of the Platreef are concentrated in the lower portion of the package, whereas in the northern sector they are concentrated in the upper part although in both sectors the sulphide occurrences are associated with metasedimentary xenoliths. Conventional and multiple sulphur isotope analyses were undertaken on sulphides from cores from both the southern and the northern sectors. This was done in order to determine the source of the sulphur. These analyses were also conducted to examine sulphur isotope variations with changing footwall. Previous sulphur isotope data predominantly obtained from the central sector of the Platreef indicated a crustal contribution to the sulphur budget but did not provide much data on footwall sulphides so the nature of the crustal component was only implied. In this thesis sulphur from an external source was identified as having contributed to the formation of sulphides in both the southern and the northern sectors of the Platreef, especially for sulphides in proximity to metasedimentary xenoliths. In the southern sector of the Platreef this source was identified as most likely being pyritic shales of the Lower Duitschland Formation. In the northern sector, Malmani dolomites, which are suggested to have collapsed from the roof of the Platreef, are the most likely source of sulphur. Importantly, in the northern sector no sulphur is thought to have come from the Archaean granite footwall. Oxygen isotope analyses were conducted on samples from the southern sector of the Platreef to verify the presence of crustal contamination. Data collected indicated that there had been a crustal oxygen component involved in the formation of silicates that led to their partial recrystallisation. When compared to oxygen isotope data from the central sector of the Platreef it appears that there are variations along strike that most likely result due to the changing footwall. This data indicates a major contribution of oxygen-, sulphur- and other volatile-rich fluids to the Platreef. This led to the partial re-crystallisation of silicates, and in areas in close proximity to sulphur-bearing metasedimentary xenoliths aided in the formation of sulphides. These volatile-rich fluids most likely originated from metasedimentary xenoliths during metamorphism that then migrated through the Platreef package. When the observations from both the southern and northern sectors of the Platreef are compared and combined with pre-existing data for the central sector, several general observations can be made. 1. The entire length of the Platreef has been affected by contamination from crustal sulphur sources to some degree. This contamination is suggested to be from volatile-rich fluids which were released from metasedimentary crustal xenoliths and footwall during metamorphism. 2. The proximity between sulphide enrichment and sulphur-bearing sediments (as footwall or xenoliths) is important and indicates the source of the sulphur which led to sulphide formation. 3. Contamination occurred on a localised scale, depending on the composition of the sedimentary lithologies and the proximity of the contaminant to the magma. In the southern sector of the Platreef the source of the sulphur is almost certainly pyritic shales of the Lower Duitschland Formation. In the central sector, sulphur has most likely come from sulphur-rich dolomites and evaporites from the Malmani dolomites. In the northern sector, sulphur-rich fluids were released from Malmani dolomite rafts that collapsed from the roof into the magma during the emplacement of the Platreef. The Archaean footwall in this area has had little or no control on the formation of the sulphides within the Platreef.

This item is only available electronically.
The Wheal Hughes and Poona mines are situated within the Moonta-Wallaroo copper district on the NW region of Yorke Peninsula approximately 150 km NW of Adelaide, S.A. Copper mineralisation is hosted by the Moonta Porphyry, a rhyolite/rhyodacite feldspar porphyry of Early Proterozoic age. The Wheal Hughes and Poona lodes are structurally controlled tabular, en echelon and sheeted fissure veins, which strike 040-050 and have a 45deg to 60deg westerly dip. Two distinct groups of mineralisation are found to occur at Wheal Hughes: (1) the NE Leighton's lode which closely resembles Poona and is typical of Moonta lodes, and (2) the SW Wheal Hughes lode which is unique to the region, in consisting of a series of parallel veins in close proximity and having extensive wall rock alteration. Mineralisation consists predominantly of chalcopyrite and pyrite with minor components of magnetite, hematite, bornite, marcasite, carrollite, molybdenite and gold. A generic model for the mineralisation at Wheal Hughes and Poona is proposed from fluid inclusion studies and petrographic studies, and sulphur isotope, chlorite and sericite analyses together with thermodynamic modelling. Magmatic hydrothermal fluids enriched in metals migrated towards the surface via fractures, which were possibly formed from the emplacement and subsequent cooling of underlying Proterozoic granites. These fractures provided pathways for the migration of hydrothermal fluids as well as sites for the deposition of the ore bodies. Metal deposition occurred as a consequence of a two step boiling process during fluid ascent along fracture conduits, which involved the separation of gases (+ steam) from the liquid phase. Condensation and oxidation of the gas phase produced acid waters that triggered argillic alteration of the country rocks. Two possible heat mechanisms generated the hydrothermal system in the Moonta district; the disruption of the geothermal gradient by the intrusion of an igneous body at depth or a dilatancy/fluid diffusion process. In either case, the heat source generated a hydrothermal system which focussed mineralising fluids into dilatant fractures, effectively localising the mineralisation.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1991

Bibliography: leaves 267-304.
xxiv, 304 leaves : ill., maps ; 30 cm.
Salinisation of groundwater and surface water of the semi-arid Murray Basin is an issue of vital importance to the viability of agriculture in south-east Australia. The understanding of the transport and transfer of water and salts in large sedimentary aquifers is necessary for better management of water resources in the future. Assesses the usefulness of [detla]34S and [delta]18OSO42 of dissolved SO42- and 87SR/86Sr ratios as tracers of inter-aquifer mixing and rock-water interaction between and within the Murray and Renmark Group aquifers in the south-west Murray Basin.
Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1999?