Apesar de representarem apenas 1% das rochas expostas na superfície da Terra, as rochas alcalinas possuem um grande espectro composicional e são associadas a vários ambientes tectônicos terrestres. Além disso, seu estudo nos ajuda a compreender melhor a evolução térmica e geodinâmica do planeta. Potássio, sódio e cálcio são os principais elementos utilizados na classificação deste grupo de rochas, e as razões entre estes elementos nos dão pistas sobre sua origem. Este estudo experimental utilizou uma prensa hidráulica de 1000 tonf, com câmaras de perfil toroidal acopladas, para estudar o sistema kalsilita-nefelina-diopsídio-sílica anidro, a 4,0GPa (aprox. 120 km de profundidade) e temperaturas até 1400 °C, com foco nos planos lucita-nefelina-diopsídio (Lct-Nph-Di) e kalsilita-nefelina-diopsídio (Kls-Nph-Di). Os produtos dos experimentos foram analisados através de MEV-EDS e DRX Para o plano Lct-Nph-Di foram encontrados campos de estabilidade para os minerais kalsilita (Klsss), nefelina (Nphss), e clinopiroxênios (Cpxss) (ambos soluções sólidas), wollastonita e sanidina, além de três pontos invariantes: (A) Kls+Nph+Di+liquido (Lc62Ne29Di9) a 1000°C (pseudoeutético); (B) Kls+Sa+(Di+Wo)+liquido (Lct75Nph22Di2) a 1200°C (pseudoperitético), (C) Kls+Di+Wo+liquido (Lct74Nph17Di9) a 1000°C (pseudoeutético). O campo da kalsilita forma uma barreira termal entre os campos composicionais potássico/ultrapotássico e sódico do diagrama. No plano Kls-Nph-Di foram encontrados campos de estabilidade para Klsss, Nphss e Cpxss e duas fases aluminosas (espinélio e coríndon), além do ponto invariante Kls+Nph+Di(±Spl)+liquido (Kls47Nph43Di10) a 1100°C (pseudoeutético). Nossos dados sugerem que a 4,0 GPa a dissolução de K em Nphss é estendida para até 39% molar, e de Na em Klsss para até 27% molar, e que tal solução sólida parcial determina o quão ricos em K ou Na os líquidos gerados pelo sistema serão. Adicionalmente, nossos dados mostram correlaçãos entre concentrações álcalis e sílicas nos líquidos gerados: positiva para K2O, negativa para CaO, mas irregular para Na2O (este devendo depender de outros fatores). / The alkaline rocks represent only 1% of the exposed rocks on the Earth’s surface. Despite that, these rocks are a group with a wide compositional spectrum, associated to many tectonic contexts, and their study can help us to better understand the thermal and geodynamic evolution of our planet. Potassium, sodium and calcium are the main elements used in the classification of this group of rocks, and their concentration can give us insights about the origin of these rocks. We have experimentally investigated the Kalsilite–Nepheline–Diopside-Silica system at high pressure and temperature conditions (HPHT), with emphasis on silica-undersaturated volume (Leucite–Nepheline–Diopside and Kalsilite–Nepheline–Diopside planes), both at 4.0GPa (~120km deep) and dry conditions and temperatures up to 1400°C, aiming to better understand the influence of K2O, Na2O, and CaO in alkaline silica-undersaturated magmas. For the experiments, we used a 1000 tonf hydraulic press with toroidal chambers, and the run products were analyzed by XRD and SEM-EDS technique. In the Lct-Nph-Di plane we determined the stability fields for kalsilite (Klsss), nepheline (Nphss) and clinopyroxene solid solution (CPxss), wollastonite (Wo) and sanidine (Sa); and three piercing points: (A) Kls+Nph+Di+liquid (Lc62Ne29Di9) at 1000°C; (B) Kls+Sa+(Di+Wo)+liquid (Lct75Nph22Di2) at 1200°C, (C) Kls+Di+Wo+liquid (Lct74Nph17Di9) at 1000°C Kalsilite stability field represents a boundary between ultrapotassic/potassic vs. sodic compositions. In the plane Kls-Nph-Di, we found the stability fields for Klsss, Nphss and CPxss and two aluminous phases spinel (Spl) and corundum (Crn). This plane have a piercing point in Kls+Nph+Di(±Spl)+liquid (Kls47Nph43Di10) at 1100°C. Our data suggest that pressure extends K dissolution in Nph (up to 39%) and Na in Kls (up to 27%), and that these solid solutions determine eutectic positions in surrounding systems, or how much K-rich will be the generated magmas. Additionally, our data shows positive correlation between K2O and SiO2 concentration in magmas, negative correlation between CaO and SiO2 and no evident correlation with Na2O.

Abstract The crustal and upper mantle structures of the Shield on the regional scale were investigated using the data of the POLENET/LAPNET passive seismic array and the previously published models of active and passive seismic experiments in the study area. This area is centred in northern Finland and it extends to surrounding areas in Sweden, Norway and northwestern Russia. The bedrock there is mostly of the Archaean origin and the lithosphere of the region was reworked by two orogenies during Palaeoproterozoic. One of the results of the thesis was a new map of the Moho depth of the study area, for which new estimates of the crustal thickness were obtained using receiver function method and complemented by published results of receiver function studies and controlled source seismic profiles. The map differs from the previously published maps in two locations, where we found significant deepening of the Moho. The 3D structure of the upper mantle was studied using teleseismic traveltime tomography method. The resulting model shows high seismic velocities below three cratonic units of the study area, which may correspond to non-reworked fragments of cratonic lithosphere and a low velocity anomaly separating these cratonic units from each other. The regional scale studies were complemented by two smaller scale studies in upper crust level using combined interpretation of seismic profiling and gravity data. These studies were centred on Archaean Kuhmo Greenstone Belt in eastern Finland and central Lapland in northern Finland located in the crust reworked during Palaeoproterozoic. Both areas are considered as prospective ones for mineral exploration. Both studies demonstrate the advantage of gravity data inversion in studying 3D density structure of geologically interesting formations, when the Bouguer anomaly data is combined with a priori information from petrophysical and seismic datasets.

Passive seismic experiments, MOSAIC, BOHEMA I-III, EgerRift, or, PASSEQ, carried out in the region of the Bohemian Massif (BM), allowed a detailed study of velocity structure of the upper mantle. We present results of tomography studies of the upper mantle beneath the north-eastern and southern parts of the BM based on the data from the BOHEMA II and BOHEMA III experiments (2004-2006). Despite the fact that regions with the highest resolution of velocity perturbations differ in the models, tomography images are similar in overlapping parts. Models of the upper mantle show mostly low- velocity perturbations relatively to radially symmetric velocity model of the Earth beneath the BM. Limited high-velocity heterogeneity beneath the Moldanubian unit, extended in the NE-SW direction, reflects thickening of the lithosphere due to a collision of the BM with the Brunovistulian micro-plate during the Variscan orogeny. The tomography based on the data from the BOHEMA III experiment revealed significant high-velocity heterogeneity in the southern margin of the model with a subduction of the lithosphere beneath the Eastern Alps. Tomographic tests showed that effects of uncorrected velocity heterogeneities within the crust can appear as deep as 100 km and, therefore, they could lead to erroneous interpretation of...

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Les minéraux nominalement anhydres du manteau terrestre (NAMs) contiennent de l’eau en faible quantité, dissoute sous forme de défauts ponctuels, et qui affecte de manière drastique les propriétés physico-chimiques du manteau supérieur terrestre. Afin de mieux comprendre cet effet, il est nécessaire d’estimer la capacité de stockage de l’eau des phases mantelliques et les mécanismes de solubilité. De nombreuses données expérimentales sur la solubilité de l’eau dans les NAMs tels que l’olivine, le pyroxène et le grenat, sont disponibles dans la littérature. Toutefois, la majorité de ces études ont été réalisées en système simple, et à des températures ou des pressions trop basses pour être représentatives du manteau supérieur terrestre. L’objectif de cette étude était de contraindre les effets combinés de la pression, de la température et de la composition sur la solubilité de l’eau dans l’olivine et le pyroxène dans les conditions du manteau supérieur terrestre. Les expériences ont été réalisées en condition de saturation en eau dans le système MSH enrichi en fer et en fer et aluminium, à 2,5 ; 5 ; 7,5 et 9 GPa, entre 1175 et 1400°C, à l’aide d’une presse multi-enclumes. Les teneurs en eau ont été mesurées par spectroscopie infrarouge en mode polarisé, à partir d’échantillons finement double polis, sur des cristaux orientés de manière aléatoire. Al est incorporé dans l’olivine et le pyroxène selon la réaction de type Tschermak, et diminue avec la pression dans les deux phases. L’ajout d’Al3+ dans le système favorise l’incorporation de H+ dans l’olivine et surtout dans le pyroxène, mais cet effet disparaît à mesure que la pression et la température augmentent. Dans ces conditions, la solubilité de l’eau dans les deux phases est contrôlée par l’activité de l’eau dans le liquide qui se charge de plus en plus en silicates. Le mécanisme majeur de l’incorporation de l’eau dans l’olivine se fait via le remplacement de sites métalliques par 2H+, impliquant que la solubilité de l’eau dans l’olivine est directement proportionnelle à la fugacité de l’eau dans le liquide. Le partage de l’eau entre pyroxène et olivine est toujours inférieur à 1, sauf à basse pression et basse température, quand Al aide à l’incorporation de l’eau dans le pyroxène par rapport à l’olivine. Dans les conditions du manteau convectif profond, l’eau va préférentiellement dans l’olivine. L’effet de la température sur le partage de l’eau entre les deux phases est négligeable. Ces données ont permis de construire un modèle de stockage de l’eau dans l’olivine à toutes pressions et toutes températures, dans le système MFASH. En combinant ce modèle au partage de l’eau entre pyroxène et olivine calculé dans notre étude, et aux données disponibles dans la littérature sur la solubilité de l’eau dans le clinopyroxène et le grenat, nous avons pu modéliser la capacité de stockage de l’eau dans le manteau supérieur terrestre. Ce modèle prédit que la couche de faible vitesse sismique, détectée à 350 km de profondeur par les observations sismiques, peut être expliquée par la fusion partielle de matériel hydraté provenant de la zone de transition et contenant initialement 750 ppm pds H2O. / Trace amounts of hydrogen dissolved as defects in nominally anhydrous minerals (NAMs) in the mantle are believed to play a key role in physical and chemical processes in the Earth’s upper mantle. Hence the estimation of water storage in mantle phases and solubility mechanisms are important in order to better understand the effect of water. Experimental data on water solubility in NAMs are available for upper mantle minerals such as olivine, pyroxenes and garnet. However, the majority of studies are based on single phases, and at temperatures or pressures that are too low for the Earth’s upper mantle. The aim of this study was to constrain the combined effects of pressure, temperature and composition on water solubility in olivine and pyroxene under upper mantle conditions. The solubility of water in coexisting pyroxene and olivine was investigated by simultaneously synthesising the two phases at high pressure and high temperature in a multi-anvil press. Experiments were performed under water-saturated conditions in the MSH systems with Fe and Al at 2.5, 5, 7.5 and 9 GPa and temperatures between 1175 and 1400°C. Integrated OH absorbances were determined using polarized infrared spectroscopy on doubly-polished thin sections of randomly-oriented crystals. Al is incorporated in pyroxene and olivine via the Tschermak substitution and decreases rapidly as pressure increases in both phases. Addition of Al3+ into the system enhances water solubility notably in pyroxene and also in olivine. However, this effect tends to vanish as pressure and temperature increase. Under these conditions, water solubility in both phases is controlled by water activity in the fluid due to dissolution of silicate component. The main mechanism responsible for water incorporation in olivine is 2H+ substituting for metal sites, which indicates that water solubility in olivine is directly proportional to water fugacity. Water partitioning between pyroxene and olivine is always lower than unity except at low pressure and temperature, in which case Al favours water incorporation into pyroxene rather than into olivine. In the conditions of the deep convective mantle, water preferentially goes into olivine. The effect of temperature on water partitioning between the two phases is negligible. The newly collected data allowed the construction of a water storage capacity model in olivine at all pressures and temperatures in the MFASH system. Combining this model with the newly measured partitioning of water between olivine and pyroxene, as well as previous data on solubility in clinopyroxene and garnet, we are able to build a model of the water saturation curve in the upper mantle. This model predicts that the low velocity layer reported by seismic observations at a depth of 350 km depth can be explained by partial melting triggered by the rise of a hydrated mantle-transition-zone material containing 750 wt ppm H2O.

Peridotites occuring in orogenic massifs provide important insights into geochemical processes of the Earth's upper mantle by providing direct evidence of mantle evolution throughout Earth history. It has been previously demostrated (e.g. Medaris et al., 1990, 2005) that the uppermost tectonic unit of the Bohemian Massif - the Gföhl Nappe hosts a variety of peridotites that originated from different sources, including subcontinental lithosphere, suboceanic asthenosphere, and possible ultramafic layered intrusive complex. The Czech peridotites of the Gföhl Nappe has been divided into three groups, defined by Medaris et al. (1999), according to their chemical compositions, identity and relations of the aluminous phases, ortopyroxen compositions and estimated P-T conditions. According to Medaris et al. (2005) "Type I" peridotites - represented by Mohelno and Biskoupky bodies - equilibrated in low P-T regime (recording the highest equilibration temperatures - up to 1335 ⁰C at 29 kbar - among the Gföhl peridotites) consist of spinel peridotite with garnet appearing only at its margins. Peridotites are enclosed in granulites that have been extensively recrystallized mostly at amphibolite-facies conditions. Many studies have been done on this locality and a wide range of mineralogy and P-T histories has...

Pour la première fois, une étude par spectroscopie infrarouge à transformée de Fourrier et par microsonde ionique des minéraux majeurs de la croûte inférieure et des péridotites mantelliques a été entreprise afin de mieux caractériser les mécanismes d’incorporation et les teneurs en eau de ces minéraux nominalement anhydres, et de déterminer leurs compostions isotopiques en H, O, et Li pour retracer les échanges latéraux et horizontaux de l’eau dans la lithosphère continentale profonde. Les résultats montrent que: (1) Les minéraux nominalement anhydres, comme les pyroxènes et plagioclase, dans les granulites de la croûte inférieure contiennent de l’eau en trace essentiellement sous forme hydroxyles et accessoirement sous forme moléculaire, avec des concentrations (exprimées en poids H2O) allant de 200 à 2330 ppm pour les clinopyroxènes, de 60 à 1875 ppm pour les orthopyroxènes, de 65 à 900 ppm pour les plagioclases. Les teneurs calculées pour chaque roche totale d’après sa composition minéralogique et la teneur en eau des minéraux varient de 155 à 1100 ppm. (2) Les teneurs en H2O des minéraux majeurs et en roche totale de la croûte continentale inférieure sont manifestement plus élevées que celles du manteau lithosphérique sous-jacent, suggérant des variations verticales de la quantité d’H2O dans la lithosphère continentale profonde. Un tel contraste peut affecter de façon notable le comportement rhéologique de la lithosphère continentale. (3) Les rapports isotopiques de l’oxygène des pyroxènes étudiés, et probablement les roches totales, exprimés en [delta]18OSMOW , vont de ~ 4,5 à 12,5‰. Ceci indique la contribution de matériaux recyclés de la croûte continentale durant la pétrogenèse des échantillons ayant un TM18O élevé. (4) Les minéraux de la granulites sont caractérisés par des valeurs de élevées TMD, avec des valeurs de -80~-10‰ exprimées en [delta]DSMOW; les minéraux sont le plus souvent en équilibre les uns avec les autres lorsque l’on considère leurs compositions isotopiques moyennes. (5) Les compositions isotopiques du Lithium mesurée dans les minéraux de nos échantillons de granulites, exprimées en [delta]7Li par rapport à Lsvec, varient de -13 à +4.7 ‰. Ces valeurs sont donc pour la plus part inférieures à celles mesurées sur les MORB (2 – 6‰). La dispersion des valeurs reflètent l’hétérogénéité de la source des granulites, et les valeurs bassent resultent probablement de la perte par diffusion de Li pendant la mise en place des liquides silicatées provenant du manteau dans la croûte inférieure. (6) La grande hétérogénéité des teneurs en eau et en Lithium, et des compositions isotopiques de H-O-Li indique l’absence de circulation de fluide pervasive au travers de la croûte inférieure, qui aurait pour effet de supprimer les hétérogénéités à petite échelle et de les diminuer fortement à grande échelle / For the first time, systematic investigations of water content and H-O-Li isotopic compositions of minerals in lower crustal granulites, as well as water content of minerals in mantle peridotites, from eastern China have been carried out by Fourier transform infrared spectrometer and ion microprobe. The results show that: (1) Nominally anhydrous minerals, such as pyroxenes and plagioclase, in the lower crust generally contain trace amounts of structural water, with their content (H2O by wt.) varying from 200 to 2330 ppm for clinopyroxene, 60 to 1875 ppm for orthopyroxene, 65 to 900 ppm for plagioclase and 155 to 1100 ppm for the estimated bulk compositions. (2) Water contents of minerals in lower crustal granulites from eastern China, and their bulk values, are significantly higher than those in the underlying upper mantle, implying vertical heterogeneities of water distribution in the deep continental lithosphere; the contrast in water content even affect the rheological strength of the lithosphere. (3) The O-isotopic compositions of pyroxenes in the lower crustal granulites from eastern China are highly variable between different localities (~ 4.5 to 12.5‰, expressed in [delta]18OSMOW values), indicating variable influences from recycled crustal materials on their protoliths. (4) The H-isotopic compositions of granulite minerals from eastern China, are mostly in the range of -80 to -10‰ expressed in [delta]DSMOW values, and these minerals are usually in equilibrium with their [delta]D values. The relatively high [delta]D of granulite minerals may be related with degassing loss of H during the genesis of granulites. (5) The Li-isotopic compositions of granulite minerals from eastern China are usually in the range of -13 to 4.7‰, mostly lower than those of MORB (2-6‰). They reflect the source heterogeneity and are probably results of high-T Li diffusion during the intrusion of their original melts into the preexisting lower crust. (6) The large dispersion of Li and water contents and of H-O-Li isotopic results indicate the absence of any pervasive fluids in the lower crust

Variações dos tempos de percurso de fases P e PKP foram usados para tomografia sísmica do manto superior sob o sudeste e centro-oeste do Brasil. Os principais objetivos foram: Melhorar a resolução obtida pelos estudos anteriores (VanDecar et al,. 1995; Escalante, 2002; Schimmel et al., 2003, feitos de 1992 a 2001) com a inclusão de novos dados e estações, mapear as áreas que não tinham sido cobertas pelas estações anteriores, tentar mostrar a consistência da base de dados, principalmente relacionada às novas estações e verificar a robustez das anomalias encontradas. Foi estudada a influência das estações localizadas nas regiões anômalas através de inversões secundárias (retirando estações). Nesta base foram incluídos registros recentes do ano 2002 e também em registros de 2000 e 2001 para eventos utilizados nos trabalhos anteriores. Os resultados confirmaram as estruturas observadas nos trabalhos anteriores e também revelaram novas regiões anômalas, particularmente no sul do estado de Mato Grosso. Das anomalias observadas nos trabalhos anteriores, confirmamos em nossos resultados o Cráton do São Francisco como uma anomalia de alta velocidade, com suas raízes chegando a 250 km de profundidade, a anomalia de baixa velocidade interpretada como resto fóssil da pluma de Tristan da Cunha VanDecar et al. (1995), a boa correlação das anomalias rasas de baixa velocidade com as intrusões alcalinas do Cretáceo Superior Schimmel et al., (2003), a anomalia de baixa velocidade inferida por Escalante (2002) na região de Iporá em Goiás (possível região do impacto inicial da pluma de Trindade), uma anomalia de alta velocidade sob a região da Bacia do Paraná (profundidades rasas) interpretada inicialmente por Schimmel et al. (2003) como possível núcleo cratônico da Bacia do Paraná e também, nesta mesma região (maiores profundidades), uma anomalia de alta velocidade interpretada como a litosfera subduzida da Placa de Nazca (Schimmel et al., 2003 e Escalante, 2002). A nova base permitiu a expansão da área de estudo e o imageamento de anomalias de baixa velocidade na província ígnea de Poxoréu em Mato Grosso, as quais são consistentes com o afinamento litosferico proposto no modelo de Thompson et al. (1998). / Variations of P and PKP travel times were used for seismic tomography of the upper mantle beneath southeast and central Brazil. Our principal objectives were: To improve the resolution obtained by the previous studies (carried out by VanDecar et al., 1995; Escalante, 2002; Schimmel et al., 2003 between 1992 and 2001) with inclusion of new data and stations, to map areas not covered by previous stations, to show the consistency of the database, mainly of the related to the new stations and to verify the robustness of the detected anomalies. The influence of the stations located in the anomalous areas was studied through secondary inversions (removing stations). The new data set includes recent records of 2002 and also new records from 2000 and 2001 for events used in the previous works. Our results confirm the structures observed in the previous works and also revealed new anomalous regions, particularly in the south of the Mato Grosso state. We confirmed the anomalies observed in the previous works: The São Francisco cráton has as a high-velocity anomaly, with roots down to 250 km depth, the low velocity anomaly interpreted as a fossil remnant of the Tristão da Cunha plume (VanDecar et al. 1995), the good correlation of the shallow low velocity anomalies with the alkaline intrusions of the Late-Cretaceous (Schimmel et al. 2003), the low velocity anomaly inferred by Escalante (2002) in the Iporá igneous province in Goiás (possible area of the initial impact of the plume of Trindade), a high-velocity anomaly under the Paraná Basin (shallow depths) interpreted initially by Schimmel et al. (2003) as possible cratonic nucleus of the Paraná Basin and also, in this same area (larger depths), a high-velocity anomaly interpreted as the slab of the Nazca Plate (Schimmel et al., 2003 and Escalante, 2002). The new data set allowed the expansion of the study area and the imaging of low velocity anomalies in the igneous province of Poxoréu in Mato Grosso, which are consistent with the model of litospheric thinning proposed by Thompson et al. (1998).

Variações dos tempos de percurso de fases P e PKP foram usados para tomografia sísmica do manto superior sob o sudeste e centro-oeste do Brasil. Os principais objetivos foram: Melhorar a resolução obtida pelos estudos anteriores (VanDecar et al,. 1995; Escalante, 2002; Schimmel et al., 2003, feitos de 1992 a 2001) com a inclusão de novos dados e estações, mapear as áreas que não tinham sido cobertas pelas estações anteriores, tentar mostrar a consistência da base de dados, principalmente relacionada às novas estações e verificar a robustez das anomalias encontradas. Foi estudada a influência das estações localizadas nas regiões anômalas através de inversões secundárias (retirando estações). Nesta base foram incluídos registros recentes do ano 2002 e também em registros de 2000 e 2001 para eventos utilizados nos trabalhos anteriores. Os resultados confirmaram as estruturas observadas nos trabalhos anteriores e também revelaram novas regiões anômalas, particularmente no sul do estado de Mato Grosso. Das anomalias observadas nos trabalhos anteriores, confirmamos em nossos resultados o Cráton do São Francisco como uma anomalia de alta velocidade, com suas raízes chegando a 250 km de profundidade, a anomalia de baixa velocidade interpretada como resto fóssil da pluma de Tristan da Cunha VanDecar et al. (1995), a boa correlação das anomalias rasas de baixa velocidade com as intrusões alcalinas do Cretáceo Superior Schimmel et al., (2003), a anomalia de baixa velocidade inferida por Escalante (2002) na região de Iporá em Goiás (possível região do impacto inicial da pluma de Trindade), uma anomalia de alta velocidade sob a região da Bacia do Paraná (profundidades rasas) interpretada inicialmente por Schimmel et al. (2003) como possível núcleo cratônico da Bacia do Paraná e também, nesta mesma região (maiores profundidades), uma anomalia de alta velocidade interpretada como a litosfera subduzida da Placa de Nazca (Schimmel et al., 2003 e Escalante, 2002). A nova base permitiu a expansão da área de estudo e o imageamento de anomalias de baixa velocidade na província ígnea de Poxoréu em Mato Grosso, as quais são consistentes com o afinamento litosferico proposto no modelo de Thompson et al. (1998). / Variations of P and PKP travel times were used for seismic tomography of the upper mantle beneath southeast and central Brazil. Our principal objectives were: To improve the resolution obtained by the previous studies (carried out by VanDecar et al., 1995; Escalante, 2002; Schimmel et al., 2003 between 1992 and 2001) with inclusion of new data and stations, to map areas not covered by previous stations, to show the consistency of the database, mainly of the related to the new stations and to verify the robustness of the detected anomalies. The influence of the stations located in the anomalous areas was studied through secondary inversions (removing stations). The new data set includes recent records of 2002 and also new records from 2000 and 2001 for events used in the previous works. Our results confirm the structures observed in the previous works and also revealed new anomalous regions, particularly in the south of the Mato Grosso state. We confirmed the anomalies observed in the previous works: The São Francisco cráton has as a high-velocity anomaly, with roots down to 250 km depth, the low velocity anomaly interpreted as a fossil remnant of the Tristão da Cunha plume (VanDecar et al. 1995), the good correlation of the shallow low velocity anomalies with the alkaline intrusions of the Late-Cretaceous (Schimmel et al. 2003), the low velocity anomaly inferred by Escalante (2002) in the Iporá igneous province in Goiás (possible area of the initial impact of the plume of Trindade), a high-velocity anomaly under the Paraná Basin (shallow depths) interpreted initially by Schimmel et al. (2003) as possible cratonic nucleus of the Paraná Basin and also, in this same area (larger depths), a high-velocity anomaly interpreted as the slab of the Nazca Plate (Schimmel et al., 2003 and Escalante, 2002). The new data set allowed the expansion of the study area and the imaging of low velocity anomalies in the igneous province of Poxoréu in Mato Grosso, which are consistent with the model of litospheric thinning proposed by Thompson et al. (1998).