Lamprophyres are mantle-derived magmatic rocks, commonly occurring as dikes. They are readily identified from their field setting, petrography, chemical and mineralogical composition. These rocks not only provide important information on melting processes in the mantle, but also on geodynamic processes modifying the mantle. There are numerous occurrences of lamprophyres in the Saxo-Thuringian Zone of Variscan Central Europe, which are useful to track the variable effects of the Variscan orogeny on local mantle evolution. This work presents and evaluates the mineralogical, geochemical, and Sr-Nd-Pb isotopic data of late-Variscan calc-alkaline lamprophyres, post-Variscan ultramafic lamprophyres, of alkaline basalt from Lusatia, and, for comparison, of pre-Variscan gabbros. In addition, lithium isotopic signatures combined with Sr-Nd-Pb isotopic data of late-Variscan calc-alkaline lamprophyres from three different Variscan Domains (i.e., Erzgebirge, Lusatia, and Sudetes) are used to assess compositional changes of the mantle during Variscan orogeny. / Lamprophyre sind porphyrische, aus Mantelschmelzen gebildete Gesteine, die meist in Form von Gängen auftreten. Sie zeichnen sich durch auffällige und charakteristische texturelle, chemische und mineralogische Eigenschaften aus. Als ehemalige Mantelschmelzen liefern sie Information sowohl über Bedingungen der Schmelzbildung im Mantel als auch über geodynamische Prozesse, die zu metasomatischer Veränderung des Mantels geführt haben. Im Saxothuringikum Mitteleuropas, am Nordrand des Böhmischen Massivs, gibt es zahlreiche Lamprophyrvorkommen, die hier zur Charakterisierung der Mantelentwicklung während der variszischen Orogenese dienen. Die vorliegende Arbeit befaßt sich mit den mineralogischen, geochemischen und isotopischen (Sr-Nd-Pb) Signaturen von spätvariszischen kalkalkalischen Lamprophyren, von postvariszischen ultramafischen Lamprophyren, von Alkalibasalten der Lausitz und, zum Vergleich, von prävariszischen Gabbros. Darüberhinaus nutzt die Arbeit Lithium-Isotopensignaturen kombiniert mit Sr-Nd-Pb–Isotopendaten spätvariszischer kalkalkalischer Lamprophyre aus drei variszischen Domänen (Erzgebirge, Lausitz, Sudeten) zur Erkundung der lokalen Mantelüberprägungen während der variszischen Orogenese.

The multiphase Ice River Alkaline Complex is located in the Main Ranges of the Rocky Mountains about 40 km east-southeast of Golden, BC, and comprises, in order of decreasing age: (1) a rhythmically-layered mafic complex; (2) carbonatite (concentrated as a plug in the centre of the complex); (3) a zoned nepheline syenite complex, and; (4) a dyke suite consisting of syenitic dykes, late alkaline lamprophyres, and carbonatites. Petrographic, geochemical, and isotopic analysis of the dykes occurring along the eastern margin of the Ice River Alkaline Complex indicates that the syenitic dykes are the product of extensive fractional crystallization (Zr/Hf = 39 – 80; Nb/Ta = 19 – 305). These syenitic dykes can be subdivided based on mineralogy and composition into a nepheline syenite – nephelinolite group, a syenite – monzodiorite group, and an alkali feldspar granite dyke. The calculated Sm-Nd isochron age of the syenitic dykes (369 ± 15 Ma) is consistent with the accepted age of the complex (359 ± 3 Ma), and is supported by the Rb-Sr errorchron for the same samples, as well as preliminary U-Pb zircon dating. A solidification front (fractional crystallization) model has been described for the development of the Ice River Alkaline Complex, where the syenitic dykes represent structurally controlled periodic discharges from an evolving magma chamber. Isotopic evidence coupled with a U-Th-Pb EPMA date of 165 ± 8 Ma for one of the examined discordant REE-rich carbonatite dykes, indicates that at least some of the carbonatites within the Moose Creek Valley are temporally and magmatically isolated from the Ice River Alkaline complex.

Estudos mineralógicos e petrológicos foram realizados em amostras de xenólitos do manto inclusos em dique de kaersutita lamprófiro de Ubatuba (SP) (Província Ígnea da Serra do Mar) e no Kimberlito Limeira 1 (Monte Carmelo, MG; Província Alcalina do Alto Paranaíba) utilizando petrografia e geoquímica de elementos maiores e traços em minerais por microssonda eletrônica e LA-ICPMS. Os espinélio lherzolitos de Ubatuba, para os quais foram estimadas temperaturas de equilíbrio entre 750 e 950°C, representam um manto fértil, afetado por proporções variáveis, mas sempre moderadas de empobrecimento. Evidências de dois tipos de metassomatismo mantélico foram observadas em amostras distintas. Cristais de clinopiroxênio das amostras com evidências de empobrecimento prévio mais acentuado (maior Mg# de olivina e piroxênios, menor Al e Na em piroxênios, pouco espinélio) mostram enriquecimento caracterizado por alta razão LILE/HFSE, atribuído a fluidos/fundidos provenientes de zonas de subducção. Em amostra de wehrlito pobre em espinélio, por outro lado, observa-se enriquecimento de LILE e HFSE no clinopiroxênio, sugestivo de interação com fluidos/fundidos alcalinos. Os xenólitos do manto do Kimberlito Limeira 1 representam lherzolitos e dunitos, com maior variedade mineralógica e textural, para os quais foram estimadas temperaturas de equilíbrio entre 760 e 820°C. Evidências de metassomatismo modal mantélico são identificadas pela presença frequente de bolsões com concentração de minerais secundários, com notável enriquecimento de LILE e HFSE, em alguns casos com fases exóticas exclusivamente relacionadas a metassomatismo no manto superior. As assinaturas químicas das fases secundárias são semelhantes às presentes na suíte MARID e em peridotitos venulados metassomatizados de xenólitos de kimberlitos da África do Sul. Evidências petrográficas e químicas de descompressão (sugerindo a presença pretérita de granada) foram observadas em uma amostra afetada por enriquecimento com alta razão LILE/HFSE. As diferentes evidências de processos de empobrecimento e metassomatismo observadas entre os dois grupos de xenólitos estudados (Ubatuba e Monte Carmelo), são indicativas da variabilidade lateral do manto superior de fácies espinélio do sudeste brasileiro, refletindo os processos geológicos (tectônicos e magmáticos) distintos vivenciados pelas duas regiões. / Mineralogical and petrological studies were conducted in mantle xenoliths included in a kaersutite lamprophyre dyke from Ubatuba (SP) (Serra do Mar Igneous Province), and in the Limeira 1 Kimberlite (Monte Carmelo, MG; Alto Paranaíba Alkalic Province), using petrography and major and trace element geochemistry in minerals by electron microprobe and LA-ICPMS. The Ubatuba spinel lherzolites, with equilibrium temperatures ranging from 750 to 950°C, represent a fertlie mantle affected by variable but moderate depletion. Evidence of two types of mantle metasomatis were detected in different samples. Clinopyroxene crystals of the samples with evidence of stronger previous depletion (olivine and pyroxenes with higher Mg#, pyroxenes with lower Al and Na, few proportion of spinel) show enrichment with high LILE/HFSE, attributed to fluids/melts derived from subduction zone. On the other hand, a spinelpoor wehrlite shows a clinopyroxene with both LILE and HFSE enrichment, suggestive of interaction with alkaline fluids/melts. The Limeira 1 mantle xenoliths correspond to lherzolites and dunites showing more textural and mineralogical variety and equilibrium temperatures ranging from 760 to 820°C. Modal metasomatism was identified by the presence of abundant pockets with concentration of LILE and HFSE-rich secondary minerals, including in some cases, exotic phases typical of upper mantle metasomatism. The chemical signature of the metasomatic minerals is similar to those found in MARID and in veined metasomatic peridotites from South Africa kimberlite xenoliths. Petrographic and chemical evidences of decompression (suggesting the former presence of garnet) were observed in a sample affected by enrichment with high LILE/HFSE. The different evidences of depletion and enrichment processes observed in the two groups of xenoliths (Ubatuba and Monte Carmelo) indicate a lateral variability of the spinelfacies upper mantle in southeast Brazil, which may reflect the distinct tectonic and magmatic processes that affected these two regions.

Estudos mineralógicos e petrológicos foram realizados em amostras de xenólitos do manto inclusos em dique de kaersutita lamprófiro de Ubatuba (SP) (Província Ígnea da Serra do Mar) e no Kimberlito Limeira 1 (Monte Carmelo, MG; Província Alcalina do Alto Paranaíba) utilizando petrografia e geoquímica de elementos maiores e traços em minerais por microssonda eletrônica e LA-ICPMS. Os espinélio lherzolitos de Ubatuba, para os quais foram estimadas temperaturas de equilíbrio entre 750 e 950°C, representam um manto fértil, afetado por proporções variáveis, mas sempre moderadas de empobrecimento. Evidências de dois tipos de metassomatismo mantélico foram observadas em amostras distintas. Cristais de clinopiroxênio das amostras com evidências de empobrecimento prévio mais acentuado (maior Mg# de olivina e piroxênios, menor Al e Na em piroxênios, pouco espinélio) mostram enriquecimento caracterizado por alta razão LILE/HFSE, atribuído a fluidos/fundidos provenientes de zonas de subducção. Em amostra de wehrlito pobre em espinélio, por outro lado, observa-se enriquecimento de LILE e HFSE no clinopiroxênio, sugestivo de interação com fluidos/fundidos alcalinos. Os xenólitos do manto do Kimberlito Limeira 1 representam lherzolitos e dunitos, com maior variedade mineralógica e textural, para os quais foram estimadas temperaturas de equilíbrio entre 760 e 820°C. Evidências de metassomatismo modal mantélico são identificadas pela presença frequente de bolsões com concentração de minerais secundários, com notável enriquecimento de LILE e HFSE, em alguns casos com fases exóticas exclusivamente relacionadas a metassomatismo no manto superior. As assinaturas químicas das fases secundárias são semelhantes às presentes na suíte MARID e em peridotitos venulados metassomatizados de xenólitos de kimberlitos da África do Sul. Evidências petrográficas e químicas de descompressão (sugerindo a presença pretérita de granada) foram observadas em uma amostra afetada por enriquecimento com alta razão LILE/HFSE. As diferentes evidências de processos de empobrecimento e metassomatismo observadas entre os dois grupos de xenólitos estudados (Ubatuba e Monte Carmelo), são indicativas da variabilidade lateral do manto superior de fácies espinélio do sudeste brasileiro, refletindo os processos geológicos (tectônicos e magmáticos) distintos vivenciados pelas duas regiões. / Mineralogical and petrological studies were conducted in mantle xenoliths included in a kaersutite lamprophyre dyke from Ubatuba (SP) (Serra do Mar Igneous Province), and in the Limeira 1 Kimberlite (Monte Carmelo, MG; Alto Paranaíba Alkalic Province), using petrography and major and trace element geochemistry in minerals by electron microprobe and LA-ICPMS. The Ubatuba spinel lherzolites, with equilibrium temperatures ranging from 750 to 950°C, represent a fertlie mantle affected by variable but moderate depletion. Evidence of two types of mantle metasomatis were detected in different samples. Clinopyroxene crystals of the samples with evidence of stronger previous depletion (olivine and pyroxenes with higher Mg#, pyroxenes with lower Al and Na, few proportion of spinel) show enrichment with high LILE/HFSE, attributed to fluids/melts derived from subduction zone. On the other hand, a spinelpoor wehrlite shows a clinopyroxene with both LILE and HFSE enrichment, suggestive of interaction with alkaline fluids/melts. The Limeira 1 mantle xenoliths correspond to lherzolites and dunites showing more textural and mineralogical variety and equilibrium temperatures ranging from 760 to 820°C. Modal metasomatism was identified by the presence of abundant pockets with concentration of LILE and HFSE-rich secondary minerals, including in some cases, exotic phases typical of upper mantle metasomatism. The chemical signature of the metasomatic minerals is similar to those found in MARID and in veined metasomatic peridotites from South Africa kimberlite xenoliths. Petrographic and chemical evidences of decompression (suggesting the former presence of garnet) were observed in a sample affected by enrichment with high LILE/HFSE. The different evidences of depletion and enrichment processes observed in the two groups of xenoliths (Ubatuba and Monte Carmelo) indicate a lateral variability of the spinelfacies upper mantle in southeast Brazil, which may reflect the distinct tectonic and magmatic processes that affected these two regions.

Hicks Dome is a mineralized intrusive center of alkaline ultramafic dikes, plugs and diatreme breccias that produced ~1200 m of structural doming of Paleozoic sedimentary rocks in southeastern Illinois. It is part of an igneous province referred to as the "Wauboukigou Alnöite Province" or "Middle Mississippi Alkaline Province". The 40Ar/39Ar dating of biotite and hornblende from igneous rocks throughout the region has consistently produced crystallization ages of 270 +/- 2 Ma (Early-Middle Permian). Hicks Dome lies near the intersection of two aulacogens, the Reelfoot Rift and the Rough Creek Graben. The igneous rocks in the Hicks Dome area range from dark-green, porphyritic dikes, through dikes with pelletal lapilli, to carbonate cemented breccias with country rock fragments and, locally, phenocrysts or xenocrysts and pelletal lapilli. Magmatic minerals include diopside, pargasite, phlogopite-biotite, titanomagnetite, ilmenite, and apatite, as well as carbonate (ferroan-dolomite - ankerite and calcite) of possible magmatic origin. This mineral assemblage only partly corresponds with other occurrences in the middle Mississippi Valley region igneous province as melilite, garnet, olivine, and perovskite were not identified in the Hicks Dome samples. The Hicks Dome igneous lithotype is defined here as a minette, a type of calc-alkaline lamprophyre. Evidence for this classification includes abundant Al-rich phlogopite-biotite, diopside, and pargasite, and the absence of melilite, garnet, and perovskite. Additionally, plotted Al2O3 vs. TiO2 compositions of biotite-phlogopite form a trend subparallel to that of minettes and alnöites, and Al vs. Ti values for most clinopyroxenes fall in the minette field. Some other igneous occurrences in the region are classified as types of ultramafic lamprophyres. For example, the North Hutson mine (Kentucky) and the Cottage Grove (Illinois) dikes are identified as alnöites and the Wildcat Hills dike (Illinois) is regarded as an aillikite. The Hicks Dome igneous suite contains 23 - 25 wt. % SiO2 and 13 - 21 wt. % CO2, whereas regional igneous rocks contain 33 - 36 wt. % SiO2 and 1 - 2 wt. % CO2. Such high CO2 values and inferred carbonate abundance is likely related to the elevated REE values at Hicks Dome. Finally, Hicks Dome samples show relative depletions in Ti, Nb, Ta, Zr, and Hf on a spider diagram compared to other regional igneous occurrences. These data indicate more variability among provincial igneous rocks than previously realized and perhaps two types of lamprophyres, one a calc-alkaline such as at Hicks Dome, and the other an alkaline ultramafic type. Rock samples from Hicks Dome and the surrounding region that were analyzed far exceed the silica cut-off to be considered a carbonatite (sensu stricto), yet a strong, consistent spatial association of abundant carbonate with igneous rocks throughout the region and similar patterns in LIL (large ion lithophyle), HFS (high field strength) and RE (rare earth) elements with carbonatites worldwide supports that magmatic carbon was part of the lamprophyre system at Hicks Dome. Carbon and oxygen isotope values for carbonate from Hicks Dome and other regional igneous samples do not plot within the field for primary carbonatite or the field for unaltered Mississippian limestone and instead form a broad linear trend between these two reference fields. The observed isotopic trend was possibly due to alteration of primary carbonatite by magmatic-hydrothermal and later low-temperature connate fluids. Parisite and/or synchysite, two REE fluorocarbonates of the bastnäsite group, and xenotime, a Y-(REE) phosphate, were identified in the Hicks Dome samples and occur as fibroradial aggregates in dissolution cavities in fluorite and carbonate and as anhedral crystals infilling microfractures and cleavage planes of phlogopite-biotite and paragasite. These textures clearly indicate the REE minerals are secondary phases most likely resulting from hydrothermal alteration-replacement by magmatic-hydrothermal fluids. A fertile (LREE enriched) lithospheric metasomatized mantle likely sourced the Hicks Dome carbonated alkaline silicate magma that, during emplacement, domed and brecciated the Paleozoic strata, expelled magmatic-hydrothermal fluids, and generated a F-REE mineralizing fluid with abundant carbonate. Igneous activity at Hicks Dome is genetically related to F-REE-base metal mineralization hosted by diatreme breccias, and likely contributed fluorine to the connate brines responsible for the F-base metal mineralization of the surrounding Illinois-Kentucky Fluorspar District (IKFD). Although resource estimates for the Hicks Dome area are beyond the scope of this work, an economic deposit of F, REEs, and/or base metals may be present at Hicks Dome and other igneous occurrences. The igneous lithotype, mineralogy, whole rock geochemistry, and regional geologic context support such a conclusion.

Den övergripande tanken med projektet är att ta reda på vad som hände på Västra Gräddmanhällan,utanför Kalix kust, för 2 miljarder år sedan. Det görs genom att ta reda på vad det är för bergarter ochstrukturer som hittats på området och hur de korrelerar till varandra. De två huvudsakliga delarna somprojektet fokuserar på är de stromatolitiska strukturerna som finns i de sedimentära bergarterna på VästraGräddmanhällan och de magmatiska intrusionerna som går genom de sedimentära bergarterna. De skaidentifieras med hjälp av tre olika metoder som ska komplettera varandra. Alla tre metoder kräver attprover från platsen hämtas till Uppsala Universitet där de kan slipas ned till tunnslip. Det kommer finnastotalt åtta prover tagna från olika stromatolitiska strukturer, både från land och Västra Gräddmanhällanoch två stycken tunnslip från de magmatiska intrusioner som tidigare antagits vara antingen kimberliteller lamprofyr. Alla tunnslip kommer att studeras i ett optiskt mikroskop och då kommer vissa tunnslipväljas ut för att undersökas i SEM och sedan Elektronmikrosond. Det finns vissa egenskaper i de olikabergarterna som är avgörande för resultatet. I de stromatolitiska strukturerna är spår av paleobiologiviktigt. De saker som kommer att kunna ge en indikation på tidigare liv i en stromatolit är bland annatorganiskt kol och pyrit. Fynd av antingen opaka mineral, organiskt kol eller andra intressanta struktureri det optiska mikroskopet kommer därför påverka projektets gång. För de magmatiska intrusionerna blirdet istället mineralsammansättning och eventuella karbonater som blir viktiga för hur synen på Sverigesgeologiska historia kommer se ut i fortsättningen. / The overall idea of the project is to find out what happened on the Western Gräddmanhällan, off thecoast of Kalix, two billion years ago. This is done by finding out what rocks and structures that are foundin the area and how they correlate to each other. The two parts that this project focuses on is thestromatolitic structures found of the Western Gräddmanhällan and the igneous intrusions that passthrough the sedimentary rocks. They must be identified using three different methods that willcomplement each other. All three methods require samples from the site to be brought to Uppsalauniversity and then be ground down to thinsections. There will be a total of eight thin sections takenfrom different stromatolitic structures, both from the coast and the western Gräddmanhällan and twopieces of thin sections from the magmatic intrusions that are already assumed to be either kimberlite orlamprophyre. All thin sections will be studied in an optic microscope and then certain thin sections willbe selected to be examined in SEM and then Electron Microprobe. There are certain properties in thedifferent rock types that are decisive for the result. In the stromatolitic structures, traces of paleobiologyare important. The things that will be able to give an indication of past life in a stromatolite includeorganic coal and pyrite. Findings of either opaque mineral, organic carbon or other interesting structuresin the optical microscope will therefore affect the progress of the project. For the magmatic intrusions,it will instead be the mineral composition and possible carbonates that will be important for how theview of Sweden's geological history will look in the future.

Fundação de Apoio a Pesquisa e à Inovação Tecnológica do Estado de Sergipe - FAPITEC/SE / Lamprophyres occur as microgranular enclaves in the Glória Norte monzonitc Stock (588 ± 5 Ma) located in the central part of the Macururé Domain, Sergipano Orogenic System, in the Sergipe State. These lamprophric enclaves were classified as minettes and occur concentrated in an area approximately 1 km in diameter in the southeast region of the stock. The minettes present porphyritic textures (feldspars limited to matrix), panidiomorphic, granulation of the average matrix and correspond to syenites. The mafic minerals present in addition to the biotite are diopside, augite, hornblende and titanite. Perthitic orthoclase and andesine, biotite, carbonate, apatite, zircon are also present in the matrix. The chemical data of the minettes (K2O/Na2O>3, 6<%MgO>8, K2O>3%) indicates orogenic ultrapotassic magmatism (low Nb, Ta, Ti) and resulting from enriched mantle (Th/Yb>9 e 0.05<Ta/Yb<0.2). The information obtained in this study indicates that ultrapotassic mafic magmas were present during the post-tectonic event in the Sergipano Orogenic System. / Lamprófiros ocorrem como enclaves microgranulares no Stock Monzonítico Glória Norte (588 ± 5 Ma) que se localiza na parte central do Domínio Macururé, do Sistema Orogênico Sergipano, no Estado de Sergipe. Estes enclaves lamprofíricos foram classificados como minettes e ocorrem concentrados em uma área com aproximadamente 1 km de diâmetro na região sudeste do stock. Os minettes apresentam texturas porfirítica (feldspatos limitados a matriz) panidiomórfica, com a matriz de granulação média e composição modal correspondente a sienito. Os minerais máficos presentes além da biotita são: diopsídio, augita, hornblenda e titanita. Ortoclásio pertítico e andesina, biotita, carbontato, apatita, zircão são igualmente presentes na matriz. Os dados químicos dos minettes (K2O/Na2O>3, 6>%MgO>8, K2O>3%) indica magmatismo ultrapotássico orogênico (baixos valores de Nb, Ta, Ti) e resultante da fusão de manto enriquecido (Th/Yb>9 e 0,05<Ta/Yb<0,2). As informações obtidas neste estudo indicam que magmas máficos ultrapotássicos foram presentes durante o período pós-tectônico no Sistema Orogênico Sergipano. / São Cristóvão, SE