Litogeoquímica E aspectos Petrogenéticos dos basaltos da Província Magmática do Paraná na porção centro-norte do Estado de São Paulo

The petrographic and geochemical characterization of flood basalts of Serra Geral Formation are here presented. The investigated areas are situated in four different regions of São Paulo state: Jaú, Ribeirão Preto, Franca and Fernandópolis. They represent almost the total area of outcrops of basalts in the São Paulo State. The petrographical data reveals that these rocks are constituted mainly by plagioclase (30-40%), pyroxenes, augite and pigeonita (20-30%) and magnetite (5-15%), and show a intergranular texture and its varieties intersertal, hialophitic and pilotaxitic. The geochemical data show a basic and tholeiitic affinity of the studied basalts, with high-Ti content (TiO2 > 1.8%), typical of the northern region of Paraná Basin. Three different magma-types were recognized: Paranapanema, Urubici and Pitanga. The first magma-type is concentrated in the Fernandópolis region, the second in the Franca region, and the Pitanga occurs in the Ribeirão Preto and Jaú regions. The distribution patterns of these magma-types and the detailed study of geochemical data showed that they are, probably, generated by a melting of a continental lithospheric mantle.

Parâmetros físicos pré-eruptivos do magmatismo ácido da província magmática do Paraná: Resultados preliminares

A set of 12 samples of acid rock types Palmas (ATP) and Chapecó (ATC) was used to determine the chemical composition of plagioclase and pyroxene by electron microprobe, with the purpose to get information about the pressure and temperature of crystallization of these rocks. The results show that the pyroxene of ATP rocks (3,2 ± 1,2 kbar, max = 5,1 kbar and 1028 ± 38°C) were formed under pressure conditions higher than those ATC (1,8 ± 0,9 kbar, max = 3,4 kbar and 995 ± 26oC). However, the pressures obtained from plagioclase showed higher pressures for ATC (3.2 ± 1 kbar, max = 6,4 kbar and 1033 ± 12°C) than ATP (1,9 ± 1 kbar, max = 4,8 kbar and 1043 ± 5°C), suggesting that the crystallization of rocktype ATP began with the formation of pyroxene and plagioclase almost simultaneously at a depth of around 17 km while the ATC, began with the crystallization of plagioclase at a depth of about 21 km (assuming a gradient of 3,3 kbar/km). The geothermometry of plagioclase allow us to calculate the concentration of water from about 1 ± 0,3% H2O for both acid rock types. Additional calculations allow us to get the depth of water exsolution of magmatic liquid at 30m below the surface. Although the data are still preliminary and insufficient to model the extrusion of these rocks, they point out to an effusion mechanism of a partially fluidized magma by volatile, which would spread to large areas with small friction with the surface that would increased with the increase of viscosity caused by the loss of volatile and decreasing of temperature, developing coherent structures as lava flows.

Petrologia e caracterização geoquímica das fontes mantélicas da região noroeste da província magmática do Paraná

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Quimioestratigrafia do vulcanismo ácido mesozóico da província magmática do Paraná: porção SE do estado de Santa Catarina

The Mesozoic acid volcanism of the Paraná-Etendeka Province can be considered as one of the biggest events of its kind in the Earth's surface, and its study have attracted special interest in characterizing the end of magmatism that preceded the rupture process and the formation of continental Africa and South America Although significant, the acid volcanism featuring Members Chapecó Palmas and Serra Geral Formation represents only 2.5% of the total generated by the magmatic rocks and perhaps therefore the existing literature on these rocks is well less significant than that on the basalts. However, there are still aspects still unclear about the origin and evolution of these rocks in relation to the associated basalts. Thus, two profiles were selected, called RA and TA, which be a systematic collection of samples from the base where the Botucatu Formation sandstones occur at the top, where they observe Palmas acid rock type. These samples should be analyzed for major, minor and trace elements and treated in specific diagrams to define the vertical variation lithochemistry and their possible relationships with the associated basalts

Estratigrafia do vulcanismo mesozóico ácido da província magmática do Paraná

The Paraná Magmatic Province was generated by a large volcanic event occurred in the Lower Cretaceous, it was a phenomenon that preceded the fragmentation of the supercontinent Gondwana. In Brazil the volcanic rocks overlying about 75% of the surface of the Parana basin being the Serra Geral Formation essentially represented by basalts and andesites of tholeiitic nature and subordinate porphyritic rhyodacites, called Chapecó type and aphyric rhyolites, Palms type. Based on the chemical compositions, rocks of Palmas type are subdivided into Santa Maria, Clevelândia, Caxias do Sul, Jacuí and Anita Garibaldi. Rocks of Chapecó type are grouped into three distinct subtypes called Guarapuava, Tamarana and Ourinhos. These acidic rocks that overlying basalts are of two main types: high-Ti (Paranapanema, Pitanga and Urubici) and low-Ti (Gramado, Esmeralda and Ribeira). Representative profiles of these rocks were studied in detail in order to establish the lithostratigraphy and Chemostratigraphy of Palmas and Chapecó type. To do this was made a field work and the use of a database with 1109 samples with their geographical coordinates and geochemical information of major and trace elements, which were launched in maps generated by Google Earth. From these maps, it was verified that rocks of the Palmas type are distributed predominantly in the south region of the basin in the state of Rio Grande do Sul, accumulated along Torres Syncline, while those Chapecó type occur in the plateaus of midwestern Paraná, in this region was observed that Chapecó type overlap those Palmas type. In the profiles studied, within Palmas type, Caxias do Sul type is spread throughout the southern region of the basin, occurring at the base of the acid volcanic sequences, in other words, they are older compared to the others. It was also observed that the rocks of Santa Maria and Anita Garibaldi type occupy the top of the sequences, both covering rocks of Caxias do Sul..

Vulcanologia e petrologia das rochas vulcânicas ácidas da Província Magmática do Paraná

Pós-graduação em Geologia Regional - IGCE

Geologia e aspectos petrológicos das rochas intrusivas e efusivas mesozóicas de parte da borda leste da Bacia do Paraná no Estado de São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A formação Serra Geral na porção centro-norte do estado de São Paulo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Rochas basálticas da formação serra geral no município de Araçatuba, estado de São Paulo

Pós-graduação em Geologia Regional - IGCE

Geomorfometria da região de Fartura (SP)

Pós-graduação em Geociências e Meio Ambiente - IGCE

Caracterização magnetométrica do Sill de Limeira-SP

The purpose of this study is to characterize the geological subsurface structure of the diabase sill of the Paraná Magmatic Province intruded in the Itararé Group, located near the city of Limeira, in the east-central region of São Paulo state. The magnetometric method served as an important tool defining the igneous body in view of the great contrast between the physical properties of the diabase sill and the host sandstones. Previous cartographic data signaled in region a possible lateral continuity in subsurface, of the various sills that occur in the region. However, the magnetic data obtained herein indicate that the area of occurrence of this body is very restricted and independent of the others observed in the region. The analysis of the radial average power spectrum obtained allowed determine the interval of number of waves adequate for the separation of shallow and deep sources, and thus conclude that the sill of the Limeira region is located more than 100 m deep.

Evolução termocronológica por traços de fissão em apatita e zircão das Bacias da Transição Proterozóico-Fanerozóico de Camaquã (RS), Castro (PR), Eleutério (SP/MG), Jaibaras e Cococi (CE)

Pós-graduação em Geologia Regional - IGCE

Caracterização magnetométrica de Sill de diabásio na região de Limeira - SP

Pós-graduação em Geologia Regional - IGCE

Contexto tectônico dos granitóides neoproterozóicos da faixa de dobramentos paraguai, MS e MT

The Neoproterozoic Granitic Province from the southeast of Mato Grosso and Mato Grosso do Sul region is constituted by seven distinctive granitic bodies, emplaced in the epimetamorphic rocks of the Cuiabá Group and related to the evolution of Paraguai Folded Belt. The Northern portion crops out in Mato Grosso State and is constituted by São Vicente, Araguaiana and Lajinha batholiths; the Southern portion crops out in the Mato Grosso do Sul State and is represented the Sonora, Coxim Rio Negro and Taboco massifs. The structural evolution is evidenced by the presence of three deformational phases, the first one is characterized by axial planar foliation (S 1), parallel or sub parallel to S 0, with attitude N60E/70NW; the second constitutes the most important phase for the tectonic arrangement and is defined by a slaty and/or crenulation cleavages (S 2), with attitude N10W/30SW and contact metamorphism associated to the emplacement of granitic bodies, the third phase is characterized by a weak retrometamorphic cleavage (S 3) with attitude N10E/ 80NW, that evolves local and gradually to strike-slip shear zones. The geological data suggest that this province was formed syn- to post tectonic to the D2 deformational set associated to the end of the collisional event in the Southeastern of the Amazonian Craton.

As rochas intrusivas da Formação Serra Geral na Porção leste da Bacia do Paraná no Estado de São Paulo: Aspectos petrográficos e geoquímicos - Resultados preliminares

The purpose of this paper is to present preliminary aspects of the petrography and chemistry of intrusive rocks (sills and dykes) from the eastern portion of the Parana Basin in the State of Säo Paulo. Data from 80 samples of the region show a subaphyric and subophitic nature and have plagioclase (25-50%), augite (3-39%), pigeonite (0-10%) and magnetite (4-20%) as an essential minerals. Apatite and quartz are present as accessory minerals. The geochemical data of intrusive rocks show a basic to intermediate composition (48% < SiO 2 < 56%) and a high Ti nature (TiO 2 > 2%). Based on the minor and trace composition of the intrusive rocks, two different magma types were recognized, named Paranapanema and Pitanga. The spatial distribution of these magma types is not alleatory in the studied region. The intrusive rocks of Pitanga magma type are displayed in the Campinas-Paulinia region, while the Paranapanema magma type cover a large region above that one, between Rio Claro and Cajuru. Furthermore, the chemical composition of the lava flows of the Serra Geral Formation, sampled in this work, reveals a magma of Urubici type. So, the intrusive rocks of the eastern portion of the of State Säo Paulo are not the extension of the lava flows, or they aren't a portions which don't reach the surface.