Understanding the Mahomet Aquifer: Geological, Geophysical, and Hydrogeological Studies in Champaign County and Adjacent Areas

Illinois American Water, Contract No. IL Amer Water 2007-02899Ope

Geochemistry and petrogenesis of the East Branch Brook metagabbroic dykes in the Sawyer Brook fault zone, Clarence Stream gold prospect, southwestern New Brunswick

The East Branch Brook (EBB) metagabbroic dykes, host to a portion of the Clarence Stream gold deposit, are situated within the contact metamorphic aureole of the Middle Devonian I-type Magaguadavic Granite on the northwestern margin of the post-orogenic Saint George Bathohth. They are highly deformed, light- (type I), intermediate- (type 2) to dark-coloured (type 3) dykes containing auriferous quartz veins that occupy brittle to ductile northeast-trending shear zones in shallow marine, hornfelsed, volcaniclastic, sedimentary rocks of the Silurian Waweig and Oak Bay formations. The shear zones parallel the regional structure as a result of proximity to the faulted boundary (Sawyer Brook fault) between the Ordovician St. Croix terrane to the northwest and the Silurian to Early Devonian Mascarcne Basin to the southeast. Geochemical studies of the EBB dykes indicate that three pulses (Fe-rich. intermediate, and Mg-rich) of subalkaline to slightly alkaline continental tholeiitc magmas were generated in a transpressional environment during the Early Silurian to Early Devonian Positive εNd values indicate their derivation from a partially depleted mantle source during faulting and nft-related events Although the geochemical data (Fe- and Ti-depletion) indicate calc-alkaline affinity for the nearby Bocabec intrusive complex, εNd values and primitive mantle-normalized spider diagram patterns are similar to those of the EBB dykes. In contrast, the St. Stephen Intrusion appears more primitive with within-plate tholeiitic to slightly alkalie affinity RÉSUMÉ Les dykes metagabbroïques du ruisseau East Branch, qui abritent une partie du gite aurifière dc Clarence Stream, sont situées à l'inténeur de 1'auréolc de métamorphismc de contact du granite du Dévonian moyen de type 1 de Magaguadavic sur la limite nord-ouest du batholithe postorogénique de Saint George. Il s'agit de dykes extrémemeni déformés de teinte pàle (type 1) et intermédiaire (type 2) à foncée (type 3) renfermant des filons de quartz aurifere qui occupent des zones de eisaillement cassantes à déformables, orientées ver\ Ic nord-est. dans des roches sédimcntaires volcanoclastiques à coméenncs marines peu profondes des formations silunennes de Wawcig el d'Oak Bay. La proximilé de la limite faillée (faille du runsseau Sawyer) entre le terrane ordovicien de St. Croix, au nord-ouest et le bassin du Silurien au Dévonien inférieur de Mascarenc. au sud-est, a amené les zones du eisaillement à longer parallélement la structure régionale. Des éludes géochimiques des dykes du ruisseau East Branch révèlent que trois impulsions (composante riche en Fer. composante intermédiaire et composante riche en Mg) de magmas tholéutiques continentaux, allant de subalcalins à légèrement alcalms sont survenues dans un environnement transpressionnel pendant la période du Silurien inferieur au Dévonien infèrieur. Les vateurs positives de εNd lémoignent de leur provenance d'un manteau particllement appauri pendant la formation de failles et des phénomènes apparcntes à une distension Même les données géeochimiques (appaurassement en Fe et en Ti) revèlent unc affinité calcoalcaline du complexe intrusif proche de Bocabec. les valeurs de εNd et les configurations de diagrammes en araignée normalisées du manteau primitif sont analogues a celles des dykes du ruisseau East Branch Par contre, l'intrusion de Saint Stephen semble plus primitive avec une affinite mira-plaques allant de tholénlique à légèrcment alcaline Traduit par la rédactio

The characterisation and leaching behaviour of coal washery tailings

This work investigates the ultrafine component of the reject stream from West Cliff Colliery, near Appin, on the NSW South Coast. The tailings studied were less than 118|im in size. The tailings were characterised mineralogically and elementally, using analytical techniques such as XRD, SEM, Y-Spectrometry and ICP. A series of standard and modified leaching tests, based on the BEOP-31 standard, was used on the tailings to determine the release of four of the primary elements, and ten heavy metal elements, under different leaching conditions. The tailings were found to consist mainly of kaolinite, siderite, including a magnesium-bearing siderite, calcite and quartz, with lesser amounts of illite and magnetite. Kaolinite was considered to be the primary source for aluminium in the leachates, siderite for iron, calcite for calcium, and the magnesium-bearing siderite for magnesium. The release of calcium and magnesium was relatively high, saturating the leachates, and accounting for the alkalinity. The pH of the leachates increased rapidly from 4 of the initial leaching solution to 9. The release of the heavy metals was very low. The leaching of manganese differed from the other heavy metal elements, and appeared to parallel that of magnesium and calcium for at least some of the leaching time. The release of the heavy metals from the tailings was generally much less than the concentrations recommended for potable water by the SPCC. Geochemical modelling of the leaching system was able to predict pH and magnesium and calcium concentrations in the leachates reasonably well. Modelling of the dissolution of siderite and kaolinite was not successful probably due to the complex behaviour of these minerals in aqueous systems

The Newsletter of the International Fission-Track Community

Editor's Notes -- Short Tracks -- Forthcoming Meetings -- Recent PhD Theses: Thermotectonic Evolution Of Kraishte, Western Bulgaria / By Alexander Kounov -- Exhumation Of The Northern Sub-Andean Zone Of Ecuador And Its Source Regions: A Combined Thermochronological And Heavy Mineral Approach / By Geoffrey Ruiz -- Tectonic Evolution Of An Active Orogen As Reflected By Its Sedimentary Record; An Integrated Study Of The Tertiary Piedmont Basin (Internal Western Alps, NW Italy) / By Barbara Carrapa -- Exhuming The Alps Through Time: Clues From Detrital Zircon Fission-Track Ages / By Matthias Bernet -- The Thermotectonic Evolution Of The Northern Precambrian Shield, Western Australia / By Ursula Weber -- The Australian Replacement Research Reactor At Lucas Heights / By Paul Green -- Using TEM Grids As Reference Crosses On Fission-Track Slides / By Trevor Dumitru -- Fission-Track Papers 2001 To 2003 -- International Fission-Track Directory -- Call For ContributionsUT Librarie

Dados preliminares de paleomagnetismo nas intrusões básicas associadas ao vulcanismo Serra Geral na porção nordeste do Rio Grande do Sul

As intrusões pertencentes ao Grupo Serra Geral vêm sendo estudadas, pois possuem importância para o entendimento da formação das rochas vulcânicas e seu ambiente gerador. Novas técnicas, baseadas em paleomagnetismo, têm sido usadas nos últimos anos para auxiliar na compreensão dos diversos processos geológicos envolvidos na geração e desenvolvimento deste vulcanismo. A mineralogia magnética presente nas rochas possibilita o uso de métodos paleomagnéticos que visam identificar a magnetização remanente preser vada, resultando em dados vetoriais de declinação, inclinação e intensidade no momento de cristalização da rocha, bem como a identificação da mineralogia, através de ciclos de histerese, e possibilitam um entendimento mais completo da unidade geológica. Através da desmagnetização por campos alternados, seis, dos nove sítios analisados, mostraram bons resultados, tendo total desmagnetização em torno de 60 mT . Os outros três sítios desmagnetizaram parcialmente, indicando que a rocha possui minerais de baixa e alta coercividade. São apresentados novos dados paleomagnéticos para os diques da porção nordeste do Grupo Serra Geral . Através de curvas de histerese e de magnetização remanente induzida, verificou-se que os principais portadores magnéticos são magnetita/titanomagnetita , de tamanho pseudo - domínio simples. Na estatística por grupo de Fisher , todos os sítios indicam polos com direções de polaridade normal. Para a obtenção de um polo magnético, é necessário analisar mais amostras para se obter uma boa estatística de dados, porém, é comprovado, através desse trabalho, que a análise paleomagnética tem muito a agregar no entendimento da evolução e formação do Grupo Serra Geral e na Província Magmática como um todo.The intrusions belonging to the Serra Geral Group have been studied, as they are important for understanding the formation of volcanic rocks and their generating environment. New techniques, based on paleomagnetism, have been used in recent years to help understand the different geological processes involved in the generation and development of this volcanism. The magnetic mineralogy present in the rocks allows the use of paleomagnetic methods that aim to identify the preserved remanent magnetization, resulting in vector data of declination, inclination and intensity at the time of crystallization of the rock, as well as the identification of the mineralogy, through hysteresis cycles, and enable a more complete understanding of the geological unit. Through alternating fields demagnetization , six of the nine sites analyzed showed good results, with total demagnetization around 60 mT. The other three sites partially demagnetized, indicating that the rock has low and high coercivity minerals. New paleomagnetic data for the northeastern portion of the Serra Geral Group are presented. Through hysteresis and induced remanent magnetization curves, it was verified that the main magnetic carriers are magnetite/titanomanetite, of simple pseudo - domain size. In Fisher's group statistics, all sites indicate poles with directions of normal polarity. To obtain a magnetic pole, it is necessary to analyze more samples to obtain good data statistics, however, it is proven, through this work, that paleomagnetic analysis has much to add to the understanding of the evolution and formation of the Serra Geral Group and in the Magmatic Province as a whole

Understanding the fluid pathways that control the Navan ore body

This work is focused on carbonate-hosted base metal deposits in the Irish midlands with emphasis on the Navan ore deposit, County Meath, Ireland. The Irish ore deposits were created by the mixing of two fluids, a metal-bearing fluid and a sulfur-rich brine. Herein I aim to further the understanding of the creation, movement, and mixing of these two fluids and how they created the giant Zn and Pb deposit at Navan, as well as how post-ore genesis fluids are recorded in the rocks around Navan. The first chapter contains a summary of current knowledge and views of the deposit, local lithologies, structures, and mineralization. The second chapter is original work that examines how metal distribution patterns and 3D meshes of the paleo-surfaces can yield insights into the movement of mineralizing fluid during ore genesis. This work builds on previous work over the many years the mine has been operating. This new work shows the spatial variability in Pb and Zn concentrations and ratios and interprets these values with respect to vertical and horizontal fluid flow. It also builds on the work of others to interrogate the extent to which a major paleo-erosion event and surface has affected the mineralization found above and below this surface. This has significant bearing for the future of exploration in the area. The third chapter is original work that contains new noble gas data from Navan and deposits across Ireland that elucidate the temperature and tectonic setting that drove the metal bearing fluid that made the Irish midlands so well-endowed in base metals. Sulfides from every major carbonate-hosted base metal mine in Ireland were crushed to release noble gases trapped in fluid inclusions, which had retained 3He/4He signatures from the time of mineralization ca. 350 Ma. These 3He/4He ratios indicate a small but clear contribution of mantle-derived 3He, which reveals that mineralization occurred during an extensional event that introduced heat from the mantle. The fourth chapter is original work based on new 40Ar/39Ar geochronological results that constrain the timing of a later fluid flow event caused by the Variscan compression that inverted the local basin. This inversion event created large wrench and reverse faults and has greatly complicated the local lithology and metal extraction. The timing of this inversion event was interrogated by analyzing the 40Ar/39Ar systematics of disturbed feldspars along a large reverse fault. The 293 ± 3 Ma minimum age produced represent the first radiometric age of the Variscan compressional event in central Ireland and confirms the long held assumption that these faults are related to this large scale tectonic event. The fifth and final chapter is a combination of original and recently published work from others. It focuses on a newly discovered area of mineralization several km to the south of Navan. Mineralization, fluid inclusions, and the structural setting of this new area are evaluated and compared to ‘typical’ Navan mineralization. The new area was created by hotter hydrothermal fluid and did not mix with the surface fluid as effectively as the main deposit

Investigating the Distribution and Source(s) of Lunar Volatiles

Following the renewed interest in the volatile inventory of the Moon witnessed in the last decade, from both sample studies and data from orbital missions, it is timely to reassess the distribution and likely source(s) of light element volatiles (C, N, He, Ne, and Ar) in a diverse suite of lunar mare basalts and soils, providing new insights about volatiles indigenous to the lunar interior, volatiles produced in situ at the lunar surface, and volatiles delivered to and implanted into the lunar surface. Simultaneous static-mode mass spectrometric measurements of these key volatiles, extracted from the same aliquot of sample by high-resolution stepped combustion, enable a more detailed identification of the different volatile components present by comparing their varying release patterns across a range of temperature steps. Taken in context with other studies of different volatile elements, this new data contributes towards a greater understanding of the Earth-Moon system, with additional implications for future in situ resource utilisation at the lunar surface. With an average δ15N value of +0.93 ± 9.39 ‰, the indigenous N component measured in mare basalts is most compatible with a CO carbonaceous chondrite source for nitrogen in the lunar interior, although some caveats exist. Variations in abundance and isotopic composition of indigenous nitrogen imply a heterogeneous lunar mantle. Assuming up to ~50 % loss of solar wind 36Ar from lunar soils, nitrogen trapped in soils can be reconciled with up to 87 % being contributed from a non-solar source with an isotopic composition of between +87 ‰ and +160 ‰. Noble gases in soils are dominated by solar wind components, with only minor amounts of cosmogenic neon being released at the highest temperature steps. In mare basalts, noble gases are a mixture of trapped, radiogenic, and cosmogenic components (from which cosmogenic production rates can be calculated and exposure ages for previously undated samples suggeste