cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.7513811.v1
title: Geochemistry and geochronology U-Pb Shrimp of granites from Peixoto de Azevedo: Alta Floresta Gold Province

description: The analysis of petrographic, geochemical and geochronological data of granites in the Peixoto de Azevedo region, Mato Grosso, Brazil, in the eastern portion of the Alta Floresta Gold Province, led to the recognition of two granitic bodies bounded by regional major faults and shear zones. In the northwestern portion a body with featured as biotite granodiorite, coarse-grained, with porphyritic to inequigranular texture, metaluminous to peraluminous, high-K calc-alkaline and magnesium character. In the southeastern portion of the area, a biotite monzogranite coarse-grained, with equigranular to porphyritic texture, slightly peraluminous, high-K calc-alkaline and dominantly of ferrous character. U- Pb dating (SHRIMP) showed that the biotite monzogranite has an age of 1869 ± 10 Ma, similar to the Matupá Intrusive Suite, while the biotite granodiorite has an age of 1781 ± 10 Ma, that is the age expected to Peixoto Granite. Both units show patterns of rare earth elements with enrichment of light over heavy and negative Eu anomaly (LaN/YbN " 7.6 to 17.31 and ratios Eu/Eu* between 0.46 - 0.72 for biotite monzogranite and LaN/YbN " 7.13 to 29.09 with ratios Eu/Eu* between 0.25 - 0.40 for the biotite granodiorite). Trace elements pattern for both present negative anomalies of Ba, P, Ti and Nb indicating an evolution from mineral fractionation and subduction related sources. In this paper, it is sugested that the monzogranite Matupá was developed in mature arc tectonic environment. For the Peixoto Granite, two hypotheses are suggested: (a) it was developed in younger magmatic arc environment associated with the Colider Magmatism or (b) it was generated in extentional tectonic environment during the Columbia Supercontinent break up.
DOI: 10.6084/m9.figshare.7514711
title: The potential of CBM (Coalbed Methane) generation in the South Santa Catarina reserve: 1. petrographic and chemical characteristics of the coal seams in Rio Bonito Formation, Paraná Basin

description: Currently, CBM is an important source of alternative energy in Brazil. The most important coal bearing sedimentary succession occurs in the Paraná Basin, and the largest reserves are located in RS and SC. This work aims to analyze the chemical and petrological characteristics of coal seams from three boreholes, being recently conducted in the South Santa Catarina coalfield, in the areas of Treviso and Ararangua (SC), in order to assess the capacity to generate associated methane gas. Samples of seven coal seams were collected (Barro Branco, Irapuá, seam A, Bonito Superior, Bonito Inferior, Pré-Bonito Superior and Pré-Bonito Inferior) from the Rio Bonito Formation, and were prepared and submitted for petrographic and chemical analysis. The lithotype banded dull (BD) was prevalent in hole CBM-SC-2012, and dull (D) in hole CBM-SC-2013. Petrographic results indicated average vitrinite reflectance values from 0.60 to 1.26 % Rrandom, classifying the seams according to rank from high volatile bituminous C to medium volatile bituminous. Maceral analysis showed significant variation in maceral composition, with predominance of vitrinite and inertinite. Results from the proximate analysis showed ash variation from 34.93 to 65.70 wt%, whereas the gross calorific value varied from 1858.0 to 5074.8 cal/g. The carbon content ranged from 4.15 to 65.81 wt%, and sulfur ranged from 0.22 to 12.43%. According to the analyzed parameters, the Barro Branco and Irapuá seams present characteristics suitable for the generation of natural gas, whereas the Bonito seam has a lower gas generation potential because of its high ash content.
DOI: 10.6084/m9.figshare.7514711.v1
title: The potential of CBM (Coalbed Methane) generation in the South Santa Catarina reserve: 1. petrographic and chemical characteristics of the coal seams in Rio Bonito Formation, Paraná Basin

description: Currently, CBM is an important source of alternative energy in Brazil. The most important coal bearing sedimentary succession occurs in the Paraná Basin, and the largest reserves are located in RS and SC. This work aims to analyze the chemical and petrological characteristics of coal seams from three boreholes, being recently conducted in the South Santa Catarina coalfield, in the areas of Treviso and Ararangua (SC), in order to assess the capacity to generate associated methane gas. Samples of seven coal seams were collected (Barro Branco, Irapuá, seam A, Bonito Superior, Bonito Inferior, Pré-Bonito Superior and Pré-Bonito Inferior) from the Rio Bonito Formation, and were prepared and submitted for petrographic and chemical analysis. The lithotype banded dull (BD) was prevalent in hole CBM-SC-2012, and dull (D) in hole CBM-SC-2013. Petrographic results indicated average vitrinite reflectance values from 0.60 to 1.26 % Rrandom, classifying the seams according to rank from high volatile bituminous C to medium volatile bituminous. Maceral analysis showed significant variation in maceral composition, with predominance of vitrinite and inertinite. Results from the proximate analysis showed ash variation from 34.93 to 65.70 wt%, whereas the gross calorific value varied from 1858.0 to 5074.8 cal/g. The carbon content ranged from 4.15 to 65.81 wt%, and sulfur ranged from 0.22 to 12.43%. According to the analyzed parameters, the Barro Branco and Irapuá seams present characteristics suitable for the generation of natural gas, whereas the Bonito seam has a lower gas generation potential because of its high ash content.
DOI: 10.6084/m9.figshare.7513646
title: Proposal of new lithostratigraphic units for the Devonian of the Rio do Peixe Basin, Northeast of Brazil

description: Subsurface stratigraphic analysis of Devonian strata in the Rio do Peixe Basin, newly recognized by palynological studies, has resulted in the identification of two new formations assembled in the newly established Santa Helena Group. These units were characterized using cores, sidewall and cuttings samples, conventional well logs, image log and 3D seismic data. The Pilões Formation, the lower unit, is composed mainly of dark mudstones and medium-to-very fine-grained sandstones, with minor conglomerates and breccias, and the Triunfo Formation, the upper unit, comprises whitish grey, kaolinitic, coarse-grained to conglomeratic, cross stratified sandstones and conglomerates, with interbedded mudstones and fine-grained sandstones. The Pilões Formation is represented by prodeltaic lagoonal-lacustrine facies, with lesser associated subaqueous talus, debrite and sandy turbidite lobe facies, part of fandelta and delta systems. The Triunfo Formation is interpreted as braided fluviodeltaic facies. The Santa Helena Group corresponds to the Lower Devonian tectono-sequence deposited in a NW-SE-trending graben during a transgressive-regressive cycle. With 343 m of thickness (isochore) in well 1-PIL-1-PB (Pilões 1), this sequence has a non-conformity at the lower boundary and its upper boundary is an angular unconformity that represents a hiatus of about 265 Myr, at the base of the Lower Cretaceous tectono-sequence (Rio do Peixe Group). Ignimbrites and co-ignimbrite breccias (Poço da Jurema volcanic breccia) were recognized at the northern margin of the Sousa half-graben. There is evidence that the pyroclastic event is coeval with the Lower Devonian graben filling. The results of this study indicate a polyhistorical tectono-volcano-sedimentary evolution of the basin. This lithostratigraphic update brings new perspectives for geological research in the Rio do Peixe Basin, as well as in other inland basins of the Northeast of Brazil.
DOI: 10.6084/m9.figshare.7513646.v1
title: Proposal of new lithostratigraphic units for the Devonian of the Rio do Peixe Basin, Northeast of Brazil

description: Subsurface stratigraphic analysis of Devonian strata in the Rio do Peixe Basin, newly recognized by palynological studies, has resulted in the identification of two new formations assembled in the newly established Santa Helena Group. These units were characterized using cores, sidewall and cuttings samples, conventional well logs, image log and 3D seismic data. The Pilões Formation, the lower unit, is composed mainly of dark mudstones and medium-to-very fine-grained sandstones, with minor conglomerates and breccias, and the Triunfo Formation, the upper unit, comprises whitish grey, kaolinitic, coarse-grained to conglomeratic, cross stratified sandstones and conglomerates, with interbedded mudstones and fine-grained sandstones. The Pilões Formation is represented by prodeltaic lagoonal-lacustrine facies, with lesser associated subaqueous talus, debrite and sandy turbidite lobe facies, part of fandelta and delta systems. The Triunfo Formation is interpreted as braided fluviodeltaic facies. The Santa Helena Group corresponds to the Lower Devonian tectono-sequence deposited in a NW-SE-trending graben during a transgressive-regressive cycle. With 343 m of thickness (isochore) in well 1-PIL-1-PB (Pilões 1), this sequence has a non-conformity at the lower boundary and its upper boundary is an angular unconformity that represents a hiatus of about 265 Myr, at the base of the Lower Cretaceous tectono-sequence (Rio do Peixe Group). Ignimbrites and co-ignimbrite breccias (Poço da Jurema volcanic breccia) were recognized at the northern margin of the Sousa half-graben. There is evidence that the pyroclastic event is coeval with the Lower Devonian graben filling. The results of this study indicate a polyhistorical tectono-volcano-sedimentary evolution of the basin. This lithostratigraphic update brings new perspectives for geological research in the Rio do Peixe Basin, as well as in other inland basins of the Northeast of Brazil.
DOI: 10.6084/m9.figshare.7511228
title: Primary composition and diagenetic patterns of sandstones from Barra de Itiúba Formation in Atalaia High, Sergipe Sub-Basin

description: The petrologic analyses of 40 thin sections from two wells located in Atalaia High, offshore of Sergipe Sub-Basin, allowed the identification of primary composition and diagenetic patterns of Barra de Itiúba Formation. The original detrital compositions included arkoses, sublithic, and lithic sandstones. The main diagenetic processes observed were: compaction of metamorphic rock fragments and mud intraclasts, generating pseudomatrix; precipitation of quartz and feldspar overgrowths and outgrowths, cementation and grain replacement by kaolinite; dolomite and ferrous dolomite/ankerite; pyrite; iron oxides and hydroxides; and diagenetic titanium minerals, in addition to dissolution phases during eo-, meso- and telogenesis. The macroporosity in the two studied wells is primary intergranular, but there is secondary porosity due to dissolution of primary and diagenetic constituents, as well as fracture porosity. Thirteen reservoir petrofacies were defined and grouped into four reservoir petrofacies associations. They reflect the reservoir quality in microscale: good, medium and low-quality and non-reservoir. The good-quality is characterized by average total porosity greater than 15%, whereas the medium shows average total porosity greater than 7%. Low-quality presents average total porosity between 1 and 4%, and the non-reservoir has an average total porosity consistently less than 1%. Overall, the studied reservoirs consist on low-quality and non-reservoir rocks, which are intercalated with levels of medium- and good-quality. The loss of original porosity was mainly due to mechanical compaction (generating pseudomatrix), and cementation by kaolinite and dolomite. Preservation of primary porosity was favored by the presence of quartz overgrowths.
DOI: 10.6084/m9.figshare.7511228.v1
title: Primary composition and diagenetic patterns of sandstones from Barra de Itiúba Formation in Atalaia High, Sergipe Sub-Basin

description: The petrologic analyses of 40 thin sections from two wells located in Atalaia High, offshore of Sergipe Sub-Basin, allowed the identification of primary composition and diagenetic patterns of Barra de Itiúba Formation. The original detrital compositions included arkoses, sublithic, and lithic sandstones. The main diagenetic processes observed were: compaction of metamorphic rock fragments and mud intraclasts, generating pseudomatrix; precipitation of quartz and feldspar overgrowths and outgrowths, cementation and grain replacement by kaolinite; dolomite and ferrous dolomite/ankerite; pyrite; iron oxides and hydroxides; and diagenetic titanium minerals, in addition to dissolution phases during eo-, meso- and telogenesis. The macroporosity in the two studied wells is primary intergranular, but there is secondary porosity due to dissolution of primary and diagenetic constituents, as well as fracture porosity. Thirteen reservoir petrofacies were defined and grouped into four reservoir petrofacies associations. They reflect the reservoir quality in microscale: good, medium and low-quality and non-reservoir. The good-quality is characterized by average total porosity greater than 15%, whereas the medium shows average total porosity greater than 7%. Low-quality presents average total porosity between 1 and 4%, and the non-reservoir has an average total porosity consistently less than 1%. Overall, the studied reservoirs consist on low-quality and non-reservoir rocks, which are intercalated with levels of medium- and good-quality. The loss of original porosity was mainly due to mechanical compaction (generating pseudomatrix), and cementation by kaolinite and dolomite. Preservation of primary porosity was favored by the presence of quartz overgrowths.
DOI: 10.6084/m9.figshare.7517261
title: Evaluation of the potential generator Aptian-Albian oil section of the Sergipe Basin, integrating palynofacies and organic geochemistry analyses

description: Data presented in this investigation refer to studies integrating palynofacies and organic geochemistry analyses that were performed on 51 samples of PEC-41-SE-9 well, located in the Sergipe Basin, Eastern Brazilian continental margin. It was evaluated the potential for oil generation, identifying the type and degree of maturation of the organic matter. Optical analyzes show that the organic matter is composed in greater proportion by amorphous organic matter in good preservation, with high fluorescence. It also presents a 67% average concerning the total composition of the kerogen. The phytoclasts usually are well preserved in almost all the section. The palynomorphs are composed of an association, predominantly, of spores and pollen grains of genus Classopollis, featuring a predominantly arid to semi-arid climate environment at deposition time. Presence of the dinoflagellate in the upper section displays the first marine ingressions that happened in the end of Aptian. Based on the qualitative and quantitative results of kerogen, it was possible to characterize three distinct palynofacies, in which the palynofacies I had the best features for quality and preservation of organic matter. The results show total organic carbon values up to 6.39% and Rock-Eval pyrolysis data pointed to the type II kerogen rich in organic matter suitable for the formation of hydrocarbon accumulations. The hydrogen index is found between 200 and 550 mg HC/g of total organic carbon, which shows good potential for oil and gas generation. Spore color index data conclude that the organic matter is found predominantly on the immature maturation phase, with SCI values of 4.0 to 4.5, corroborating with data of maximum temperature, of up to 432°C.
DOI: 10.6084/m9.figshare.7517261.v1
title: Evaluation of the potential generator Aptian-Albian oil section of the Sergipe Basin, integrating palynofacies and organic geochemistry analyses

description: Data presented in this investigation refer to studies integrating palynofacies and organic geochemistry analyses that were performed on 51 samples of PEC-41-SE-9 well, located in the Sergipe Basin, Eastern Brazilian continental margin. It was evaluated the potential for oil generation, identifying the type and degree of maturation of the organic matter. Optical analyzes show that the organic matter is composed in greater proportion by amorphous organic matter in good preservation, with high fluorescence. It also presents a 67% average concerning the total composition of the kerogen. The phytoclasts usually are well preserved in almost all the section. The palynomorphs are composed of an association, predominantly, of spores and pollen grains of genus Classopollis, featuring a predominantly arid to semi-arid climate environment at deposition time. Presence of the dinoflagellate in the upper section displays the first marine ingressions that happened in the end of Aptian. Based on the qualitative and quantitative results of kerogen, it was possible to characterize three distinct palynofacies, in which the palynofacies I had the best features for quality and preservation of organic matter. The results show total organic carbon values up to 6.39% and Rock-Eval pyrolysis data pointed to the type II kerogen rich in organic matter suitable for the formation of hydrocarbon accumulations. The hydrogen index is found between 200 and 550 mg HC/g of total organic carbon, which shows good potential for oil and gas generation. Spore color index data conclude that the organic matter is found predominantly on the immature maturation phase, with SCI values of 4.0 to 4.5, corroborating with data of maximum temperature, of up to 432°C.
DOI: 10.6084/m9.figshare.7511858
title: The role of viscosity in the emplacement of high-temperature acidic flows of Serra Geral Formation in Torres Syncline (Rio Grande do Sul State, Brazil)

description: The acidic flows from Serra Geral Formation in Torres Syncline, Rio Grande do Sul, Brazil, are on the top of a volcanic sequence composed by a complex facies association of compound, simple and rubbly pahoehoebasic flows, acidic lava domes, and tabular acidic lava flows. The origin and emplacement conditions of the acidic volcanic rocks are discussed in this paper based on petrology, on calculated apatite saturation thermometry temperatures, and on estimated viscosity data. The liquidus temperatures for metaluminous rhyodacite to rhyolite samples are about 1,067.5 ± 25ºC in average. The viscosity (η) values vary from 105 to 106 Pas for anhydrous conditions, suggesting the emplacement of high-temperature - low-viscosity lava flows and domes. The occurrence of acidic lava domes above simple pahoehoe flows as flow-banded vitrophyres was under low effusion rates, in spite of their high temperature and low viscosities, which are reflected in their small height. The emplacement of lava domes has continued until the eruption of rubbly pahoehoe flows and the geometry of these deposits rugged the relief. Presence of tabular acidic lava flows covering the landscape indicates that it was under high effusion rates conditions and such flows had well-insulated cooled surface crusts. The capacity to attain greater distances and overpass relief obstacles is explained not only by high effusion rates, but also by very low viscosities at the time of emplacement.
DOI: 10.6084/m9.figshare.7511858.v1
title: The role of viscosity in the emplacement of high-temperature acidic flows of Serra Geral Formation in Torres Syncline (Rio Grande do Sul State, Brazil)

description: The acidic flows from Serra Geral Formation in Torres Syncline, Rio Grande do Sul, Brazil, are on the top of a volcanic sequence composed by a complex facies association of compound, simple and rubbly pahoehoebasic flows, acidic lava domes, and tabular acidic lava flows. The origin and emplacement conditions of the acidic volcanic rocks are discussed in this paper based on petrology, on calculated apatite saturation thermometry temperatures, and on estimated viscosity data. The liquidus temperatures for metaluminous rhyodacite to rhyolite samples are about 1,067.5 ± 25ºC in average. The viscosity (η) values vary from 105 to 106 Pas for anhydrous conditions, suggesting the emplacement of high-temperature - low-viscosity lava flows and domes. The occurrence of acidic lava domes above simple pahoehoe flows as flow-banded vitrophyres was under low effusion rates, in spite of their high temperature and low viscosities, which are reflected in their small height. The emplacement of lava domes has continued until the eruption of rubbly pahoehoe flows and the geometry of these deposits rugged the relief. Presence of tabular acidic lava flows covering the landscape indicates that it was under high effusion rates conditions and such flows had well-insulated cooled surface crusts. The capacity to attain greater distances and overpass relief obstacles is explained not only by high effusion rates, but also by very low viscosities at the time of emplacement.
DOI: 10.6084/m9.figshare.7519151
title: Paleoenvironmental interpretation through the analysis of ostracodes and carbonate microfacies: study of the Jandaíra Formation, Upper Cretaceous, Potiguar Basin

description: Paleoecological analyses are important tools for the reconstruction of paleoenvironments. This paper had the objective of using analysis of ostracode assemblages and carbonate microfacies of a well (Carbomil) and an outcrop (Quixeré) from the Jandaíra Formation, Potiguar Basin, in order to verify how they corroborate and complement the other. Two paleoenvironments for Carbomil Well (assemblages 1 and 2, respectively marine and brackish to neritic environments) and one for Quixeré Outcrop (assemblage 3, marine environment) were identified through the ostracode assemblage analysis. Thin section analysis allowed the identification of two different facies for Carbomil Well, i.e. bioclastic packstones to wackstones, a marine brackish or restricted marine system; and bioclastic grainstones to packstones, a normal, shallow marine system. High levels of alteration on the samples prevented an adequate analysis of Quixeré Outcrop; however, it seems to point towards a low-energy environment. Overall, information provided by the thin sections corroborate and complement data of the ostracode assemblages, which allowed a higher degree of certainty for the paleoenvironmental analysis.
DOI: 10.6084/m9.figshare.7519151.v1
title: Paleoenvironmental interpretation through the analysis of ostracodes and carbonate microfacies: study of the Jandaíra Formation, Upper Cretaceous, Potiguar Basin

description: Paleoecological analyses are important tools for the reconstruction of paleoenvironments. This paper had the objective of using analysis of ostracode assemblages and carbonate microfacies of a well (Carbomil) and an outcrop (Quixeré) from the Jandaíra Formation, Potiguar Basin, in order to verify how they corroborate and complement the other. Two paleoenvironments for Carbomil Well (assemblages 1 and 2, respectively marine and brackish to neritic environments) and one for Quixeré Outcrop (assemblage 3, marine environment) were identified through the ostracode assemblage analysis. Thin section analysis allowed the identification of two different facies for Carbomil Well, i.e. bioclastic packstones to wackstones, a marine brackish or restricted marine system; and bioclastic grainstones to packstones, a normal, shallow marine system. High levels of alteration on the samples prevented an adequate analysis of Quixeré Outcrop; however, it seems to point towards a low-energy environment. Overall, information provided by the thin sections corroborate and complement data of the ostracode assemblages, which allowed a higher degree of certainty for the paleoenvironmental analysis.