Programa de Pós-Graduação em Geologia e Geoquímica - PPGG/IG

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2603

O Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA) surgiu em 1976 como uma necessidade de desmembramento do então já em pleno desenvolvimento Curso de Pós-Graduação em Ciências Geofísicas e Geológicas (CPGG), instalado ainda em 1973 nesta mesma Universidade. Foi o primeiro programa stricto sensu de Pós-Graduação (mestrado e doutorado) em Geociências em toda Amazônia Legal. Ao longo de sua existência, o PPGG tem pautado sua atuação na formação na qualificação de profissionais nos níveis de Mestrado e Doutorado, a base para formação de pesquisadores e profissionais de alto nível. Neste seu curto período de existência promoveu a formação de 499 mestres e 124 doutores, no total de 623 dissertações e teses.

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Afinidades petrológicas e geocronologia U-Pb em zircão de ortognaisses do Complexo Gnáissico-Migmatítico Água Azul, Terreno Sapucaia, Província Carajás.
(Universidade Federal do Pará, 2024-10-09) PINTO, Eliziane de Souza; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472
The Água Azul do Norte area is part of the geological context of the Carajás Province, precisely in the Sapucaia Terrain, according to the recent tectonic compartmentalization proposals presented by the Granitoid Petrology Research Group (GPPG/UFPA). This region is formed by a mesoarchean orthognathic basement with TTG affinity (Água Azul GneissicMigmatitic Complex; 2.93 Ga) associated with late Mesoarchean intrusions with sanukitoid signatures (Água Azul and Água Limpa Granodiorites; 2.88-2.87 Ga), high-Ba-Sr sodic (Nova Canadá Granodiorite; 2.89-2.87 Ga) and high-K calc-alkaline (Boa Sorte Granite; 2.89- 2.85 Ga) signatures. The review of geological and petrographic data indicated that the TTG crust of Água Azul do Norte is compositionally heterogeneous and records strong evidence of progressive metamorphism and migmatization. Therefore, this work reclassifies this TTG basement as being formed by orthogneisses, which occasionally present variations to tonalitic to quartz dioritic compositions that resemble fragments of a more primitive, intensely deformed and gneissified crust. These varieties show compositional banding in an E-W direction, often disturbed by shear bands and drag folds. Considering the classification of migmatites, they have an orthognathic paleosome and leucosomes rich in Qz+Pl±Bt parallel to the banding (stromatic metatexite) and frequentely outlined by mafic aggregates (melanosome rich in biotite and hornblende). They form four compositional varieties: i) hornblende±biotite tonalitic orthogneiss (HBTnl), ii) clinopyroxene-hornblende tonalitic orthogneiss (CHTnl), iii) epidote-biotite orthogneiss quartz diorite (EBQzD) and iv) hornblende-biotite orthogneiss quartz diorite (HBQzD). They present a large proportion of mafic minerals (M'> 15%), especially biotite and hornblende, which can occur slightly stretched along the foliation plane. Plagioclase and secondary quartz are abundant and occur in the matrix or, in the case of plagioclase, as phenocrysts, while alkali-feldspar and primary quartz are practically insignificant. Whole rock geochemical analysis indicated that samples MED-120A (EBQzD) and MEP-53B (HBQzD) present moderately magnesian character, medium-K calcium-alkaline signature, relative depletion in K2O, MgO, Ba, Ni and Cr and enrichment in Na2O, Al2O3, TiO2, Fe2O3 and Zr, reflecting a certain affinity with traditional tonalite-trondhjemitic associations. The presence of many zircon crystals with igneous features preserved in these samples marks the crystallization age of the protolith at 3.06 Ga, suggesting that they are crustal fragments approximately 100 Ma older than the underlying crust (Água Azul Orthognathic Complex). MED-144 (HBTnl) exhibited a strongly magnesian character, high-K calcium-alkaline signature, high K2O/Na2O ratio and enrichment in MgO, Ba, Ni and Cr, very similar to the composition observed in sanukitoids. The U-Pb data obtained for this sample indicated a crystallization age of 2.92 Ga, similar to that observed in sanukitoids described in the Ourilândia do Norte region (Arraias Granodiorite). The other samples showed significant contents of compatible elements (e.g. Fe, Mg, Ni, Cr) and moderate contents of incompatible elements (e.g. K, Rb, Ba, Sr, Zr, Ti) and revealed an intermediate behavior between TTGs and granitoids enriched in Mg, as well as a strong affinity with the São Carlos Orthogneiss (2.93 Ga) described in the same terrain. Concordant U-Pb ages obtained for samples MED-95A (HBTnl) and EDC-28B (CHTnl) indicated acrystallization at 2.95-2.93 Ga contemporaneous with the emplacement of the Água Azul TTGs and the São Carlos Orthogneiss. The textural behavior of the quartz and mafic minerals indicates dynamic recrystallization mechanisms at intermediate to high temperatures (~500-650ºC), while the morphology observed in the migmatites (stromatic metatexitic and leucosomes with hydrated minerals) suggests that there was a low amount of melt produced and fluids participation in the partial melting process. Combined with the mineral paragenesis (Pl+Qz+Bt±Hbl±Ep), these factors point to a granitic protolith metamorphosed under amphibolite facies conditions, with the migmatization being strongly contemporaneous with the deformation and peak of the regional metamorphism described in the Carajás region (2.89 Ga; MED-95A).
Acesso aberto (Open Access)
As águas subterrâneas de Belém e adjacências: influência da Formação Pirabas e parâmetros físico-químicos para medidas de qualidade
(Universidade Federal do Pará, 1996-04-08) SAUMA FILHO, Michel; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
In the Metropolitan Region of Belém (PA) the water supply to the population comes from springs (physiographic area of Utinga) and from a network of positional tube wells, in general, in more remote urban areas or where pumping is precarious. This work evaluates the groundwater used in the Metropolitan Region of Belém, correlating data of physical, physical-chemical and chemical parameters, in an attempt to compose an understandable picture about the quality of these waters, and to verify the influence that they suffer from the geological units in which they are located. the aquifers that preserve them are located. To carry out the work, water samples were collected in two different seasonal periods: dry and rainy. After exhaustive consultation of the files of companies, institutions and researchers, 17 tubular wells were selected, 9 in Belém, 5 in Icoaraci, 2 in Mosqueiro and 1 in Ananindeua (Annex A). The most frequent turbidity indices were between 9 and 14 units (ppm of SiO2), but some wells showed higher values (33, 41 and 71 ppm of SiO2. Only in some cases, this turbidity can be immediately correlated with the silica content obtained by chemical analysis. The most frequent color measurements are in the range from zero to 7.5 U.C., with the zero index predominating. However, some wells showed a value above 100 U.C. and others, less frequent, with indices varying between 20 and 60 U.C. The pH and electrical conductivity were quite different parameters. Thus, the highest pH and electrical conductivity indices were verified in the aquifers of the Pirabas Formation. In these cases, the pH was around 6 .4 to 7.6 and conductivity between 231 and 362 µS/cm, with a discontinuity at 87.5 µS/cm, also attributed to a well associated with the aforementioned Formation. More acidic waters (pH below 6.38 and above of 4.01) are certainly attributed to the aquifers of the Barreiras and Post-Barreiras Group. The chemical constituents, notably the contents of Ca2+, Mg2+, Na+ and K+, are consistent with the interpretation of the numerical values of pH and electrical conductivity. Without exception, the concentrations of Ca2+ are higher than those of the other cations, establishing a decreasing order according to Ca2+> Mg2+> Na+>K+, with some inversion between Na+ and Mg2+. The highest concentrations of Ca2+ (soon followed by Mg2+) result from the dissolution of carbonates present in the Pirabas limestone. In fact, confirming this assertion, the concentrations of HCO-3 are also much higher than the concentrations of Cl- and SO2-4. It is to be expected, therefore, that the dissolution of Pirabas sediments produces higher concentrations of Ca2+ and HCO-3. The silica and iron contents also discriminate such waters. In general, higher silica contents correspond to greater depths, as would be expected, taking into account the action of chemical weathering on silicate minerals. As for iron, this constitutes a differentiating parameter of the waters of the Pirabas Formation, almost always at much lower levels than the corresponding values associated with the Barreiras and Post-Barreiras aquifers, with, however, exceptions, in which appreciable indices of iron related to Pirabas sediments. It should be noted that the Pirabas Formation appears in the Metropolitan Region of Belém almost always at depths greater than 100 m, although there are records of smaller depths, but these are apparently rarer situations, as is the case with well number 3. , on the University Campus, near the Guamá River, with a depth of 76 m, and the 94 m well of the Museu Paraense Emílio Goeldi, in the central area of the city (Annex A). The exhaustive consultation of the aforementioned archives of institutions, companies and researchers led to the realization that many tubular wells installed in the urban area use water associated with the Barreiras and Post-Barreiras aquifers, where the pH values are almost always, below 6 units, and electrical conductivity measurements rarely reach 100 µS/cm. Finally, it appears that there is a need for greater investments in order to increase the prospection and use of groundwater in the region, as these, in addition to dispensing with treatment prior to distribution, are still a source of resources, not dimensioned, but of great potential.
Acesso aberto (Open Access)
Assinatura geoquímica do ouro na Província Mineral do Tapajós, Cráton Amazônico: o exemplo dos depósitos São Jorge e São Chico
(Universidade Federal do Pará, 2025-06-19) GOMES, Iolanda Clara do Carmo; LIMA, Rafael Guimarães Corrêa; http://lattes.cnpq.br/6751523860876497; LAMARÃO, Claudio Nery; http://lattes.cnpq.br/6973820663339281; https://orcid.org/0000-0002-0672-3977
Gold has a great economic importance, and the determination of its geochemical and isotopic signatures, exploited in Brazil’s main mineral provinces, has become a valuable tool not only for mineral exploration but also for tracing its origin and circulation. The aim of this study is to characterize and compare the chemical composition of gold from two different deposits using scanning electron microscopy paired with energy-dispersive spectrometry (SEM‑EDS), to evaluate the viability in differentiating provenance on local and regional scales, and to discuss the factors controlling element distribution in native gold. São Jorge and São Chico are gold deposits located in the eastern portion of Tapajos Mineral Province, aligned along the Tocantinzinho lineament (WNW‑ESE). The gold mineralization at São Jorge deposit consists of a paragenesis formed by gold + pyrite + chalcopyrite ± sphalerite and, rarely, galena, which host two generations of gold with distinct chemical compositions. These gold phases occur either in quartz veins and/or in sulfide disseminations in strongly hydrothermally altered host rocks. In this deposit, gold is mainly hosted by pyrite, occurring in the form of inclusions with high Au contents (84.27–91.02 wt%) and filling pyrite fractures with a composition richer in Ag (7.86–15.72 wt%). The geochemical and textural differences indicate at least two distinct mineralizing events. In contrast, the São Chico deposit shows a paragenesis formed by gold + pyrite + galena + sphalerite ± chalcopyrite, in which gold occurs as electrum within polymetallic sulfide‑bearing quartz vein systems. Here, gold is mainly hosted by galena, and textural relationships between these two minerals suggest simultaneous precipitation under low‑temperature conditions. Gold in this deposit also occurs with chalcopyrite and sphalerite, as reflected in its chemical composition, which shows higher average of Cu (0.44 wt%) and Zn (0.42wt%) contents, respectively. Principal component analysis (PCA) identified Ag, Fe, and Te as the elements with the greatest potential for gold discrimination between these two deposits. Gold microparticles from the São Jorge deposit exhibits a geochemical signature with higher contents of Au (73.82–91.02 wt%), Fe (0.54–6.21 wt%), and Te (0.37–3.61 wt%), compared to gold from the São Chico deposit, which displays higher concentrations of Ag (29.82–51.42 wt%).
Acesso aberto (Open Access)
Caracterização mineralógica com espectroscopia de reflectância por infravermelho (SWIR): exemplo do Complexo máficocarbonatítico Santana, sul do Cráton Amazônico
(Universidade Federal do Pará, 2021-09-21) COSTA, Jhoseph Ricardo Costa e; FERNANDES, Carlos Marcello Dias; http://lattes.cnpq.br/0614680098407362; https://orcid.org/0000-0001-5799-2694
On the border of the Pará and Mato Grosso states, in the Amazonian Craton, municipality of Santana do Araguaia (PA), there is a volcano-plutonism named Santana mafic-carbonatitic complex. This set houses the Serra da Capivara phosphate deposit. A lower mafic-ultramafic member reveals plutono-volcanic lithofacies with pyroxenite, ijolite, apatitite, and alkaline basalt. Autoclastic lithofacies contains poorly selected deposits of massive polymictic breccia, lapilli-tuff, crystal tuff, and ash tuff. Volcanogenic epiclastics rocks cover these lithofacies. The upper carbonatite member contains plutonic lithofacies with coarse calcite-carbonatite (sövite). Fine carbonatite veins with pervasive carbonatic and apatitic alterations crosscut this lithotype. Minor thick apatitite occcurs associated to this member and represents the protore of the deposit. Effusive volcanic lithofacies reveals fine calcite-carbonatite (alvikite) with porphyritic, equigranular, or aphanitic textures. A poorly sorted lithofacies of crystals tuff, lapilli-tuff, and massive polymictic breccia completes this member. Stocks and syenitic dykes invade these lithofacies. Detailed mapping suggests that the complex is a volcanic caldera in which large zones of hydrothermal alterations occur with reddish, brownish red, and yellowish carbonatitic rocks. Petrographic observations reveal paragenesis of barite + fluorapatite + calcite + dolomite ± quartz ± rutile ± chalcopyrite ± pyrite ± monazite ± magnetite ± hematite. The application of short wave infrared spectroscopy (SWIR) revealed the chemical characteristics and their importance in the crystallinity of most of these hydrothermal minerals, such as radicals (OH- and CO3), H2O molecule, and cation-OH bonds such as Al-OH, Mg-OH, and Fe-OH. The main mineral phases identified were dolomite, calcite, serpentine, chlorite, muscovite with low, medium, and high aluminum, montmorillonite (Ca and Na), illite, nontronite (Na0.3Fe2((Si,Al)4O10) (OH)2·nH2O), and epidote. The data suggest a control by temperature, fluids composition, and fluid/rock ratio during the evolution of the Santana mafic-carbonatitic complex. This low-cost exploratory technique, which is applied in hand-held samples or drill holes on a large scale, is promising in characterization of volcano-plutonic centers in regions subjected to severe weathering conditions, as well as helping to develop models for prospecting mineral deposits of Rare Earth Elements (e.g. Nd, La) associated with alkaline-carbonatitic complexes. We can even combine this tool with artificial intelligence algorithms for more robust and faster results.
Acesso aberto (Open Access)
Desenvolvimento de uma metodologia para análise química de inclusões silicáticas em cristais de quartzo: estudo de caso em granitos estaníferos da Mina Pitinga (AM)
(Universidade Federal do Pará, 2021-05-02) SANTOS, Gabrielle Cristine Silva dos; BORGES, Régis Munhoz Krás; http://lattes.cnpq.br/4220176741850416; https://orcid.org/0000-0002-0403-0974
Silicate inclusions (melt inclusions) are small globules of silicate melt, containing some combinations of crystals, glass and vapor, entrapped in different minerals during their growth, and can be found in volcanic and plutonic rocks. They are easily identified in volcanic rocks. On the other hand, one of the major difficulties in the study of melt inclusions in plutonic rocks is their identification, because, after being trapped, their evolution results in total or partial crystallization. Based on international literature, they provide important information about the origin, nature of magmas and their petrological evolution. In addition¸ the detection of metals in melt inclusions is a unequivocal geological evidence of the genetic association of these elements with magmatic liquids (source) and is crucial in the study of orthomagmatic or hydrothermal deposits. The techniques for studying silicate inclusions for petrological and metallogenic purposes have evolved very rapidly in the last four decades, but it is a methodology that has not yet been implemented in Brazil, both due to the absence of laboratories with adequate equipment and the inexistence of research groups engaged in this field. Recently, pioneering studies were developed at the CDTN (Centro de Desenvolvimento da Tecnologia Nuclear), in Belo Horizonte (MG), with the tin granites of the Pitinga mine (AM), through high temperature microthermometric experiments and analysis of trace elements by LA-ICP-MS, in silicate inclusions hosted in quartz crystals of these granites. However, the tests were carried out on doubly-polished sections, which made it difficult to perform chemical analyzes of major elements by electron microprobe, since the inclusions were very deep in the quartz crystals, and any attempt at polishing to expose the inclusions would damage the samples. Based on this preliminary experience, this specific work is a technique for preparing quartz crystal concentrates containing silicate inclusions, using as such tin granites from the Pitinga mine (AM), representatives of the later facies of the Madeira pluton, porphyritic hypersolvus alkali feldspar granite and albite-rich granite. Thus, the developed work at the Laboratório de Inclusões Fluidas, with the crucial support of the Oficina de Laminação, the Laboratório de Análises Químicas and the Laboratório de Microanálises of the Instituto de Geociências of the Universidade Federal do Pará (UFPA), allowed the research to establish a routine involving the following steps: detailed petrography; crushing and grinding of the samples; granulometric separation; preparation of quartz crystal concentrates; muffle furnace heating and cooling experiments; selection of crystals with appropriate inclusions; assembly of the crystals in mounts with epoxy resin and subsequent polishing; monitoring and imaging of inclusions through the SEM; particle analyzes by EDS and, finally, analysis of major element (WDS) by electron microprobe. The microanalytical data (major elements) chosen especially in those silicate inclusions containing two or more solid phases (glass, spherical globules), demonstrated that the preparation technique provided a good exposure of the inclusions. In this way, the methodology developed in this work is relevant to the study of silicate inclusions and can be applied for the preparation of concentrates of any transparent magmatic mineral (quartz, olivine, pyroxene, plagioclase, etc.), host of silicate inclusions, and that can be analyzed by any of the traditional microanalytical techniques (electron microprobe, LA-ICP-MS, Raman spectroscopy, SEM, etc.).
Acesso aberto (Open Access)
Estudo geoquímico e isotópico (U-Pb/Lu-Hf) de novas ocorrências de granitos tipo-A no Domínio Carajás.
(Universidade Federal do Pará, 2023-04-18) AFONSO, Jully Mylli Lopes; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472
The Carajás Mineral Province was the setting of an extensive magmatic event, marked by anorogenic granitic intrusions and associated dykes. Geological mapping methods carried out in the central portion of the Canaã dos Carajás Domain allowed the individualization of two new anorogenic granitic stocks. These granites occur as isotropic, semicircular shaped stocks, which occur as intrusions in Archean granitic rocks of the Vila União and Cruzadão granite suites. And are classified as monzogranites and divided into biotite-monzogranite equigranular facies (BMzE) and biotite monzogranite porphyritic (BMzP) facies, where biotite is the main ferromagnesian mineral and are often associated with fluorite, in addition to allanite, zircon, apatite and epidote. They are meta- to peraluminous, with a high content of HSFE iron-related with a reduced to moderately oxidized character. When compared to others type-A granites of the Carajás Mineral Province, these granites display significant contrasts with the Jamon and Velho Guilherme suites and are similar to those observed in the Serra dos Carajás suite and, consequently, the Gogó da Onça Granite. Geochronological data of U-Pb in zircon revealed that crystallization age of these granites is ~1893 ± 13 Ma, and associated with isotopic data of Lu-Hf indicate crustal sources for these rocks, with strongly negative ƐHf values ranging from -14 at -17°C and TDM between 3.38 Ga to 3.57 Ga. Based on this informations, the geochemical modeling imply that these granites were generated from partial melting of tonalitic granites of similar composition to the Arco Verde Tonalite or Caracol Tonalite from the Rio Maria Domain. Such results are suitablewith the hypothesis that these granites were generated from a fusion of Archean granitoids and placed in a shallow crust between 1.88 and 1.86 Ga.
Acesso aberto (Open Access)
Estudo sedimentológico da Formação Pimenteira (Devoniano) na borda sudoeste da bacia do Parnaíba (TO)
(Universidade Federal do Pará, 1998-04-15) SILVA, Valter Fernandes; CAPUTO, Mário Vicente; http://lattes.cnpq.br/1028384858323270
The part of the Pimenteira Formation studied occurs in the southwest portion of the Parnaíba Basin, in the region between the cities of Paraíso, Miranorte, Miracema, Tocantinea, Pedro Afonso and Itacajás in the State of Tocantins. This formation is considered to be deposited in a transgressive sea system tract of Middle and Late Devonian age (Givetian to Famenian). In the area on stage, the studies of the facies made it possible to individualize three associations of facies named here as A, B and C that were deposited on a shallow marine platform during transgressive sea level, regressive sea level and high sea level, respectively. These facies associations were interpreted as a product of the following depositional environments: 1) LAMMA MARINE PLATFORM (association of facies A) represented by F1 (laminated shale facies), Alp (sandstone with plane-parallel lamination and Aab (sandstone intercalated to claystones with sand pockets) where the deposition took place mainly from fine suspended sediments (pelites) intercalated with fine to very fine sandstones (psamites) deposited under the influence of oscillatory and tractive flow originated by waves; 2) PROXIMAL GLACIOMARINHO with SUBGLATIAL CHANNEL, associated (association of facies B), represented by facies Dmm (massive diamictite), Acf (sandstone with fluidized clast), F1 (laminated shale), Pgm (massive coarse paraconglomerate), Pfm (massive fine paraconglomerate) and Agm ( massive coarse sandstone), were deposited from glaciers, with associated subglacial channels, ice rafts and/or icebergs that displaced from the continent, floated in the sea, released generating melt water bringing a large amount of fine and coarse sediments, forming a plume loaded with suspended sediments in front of the gallery. With the decrease in energy, extensive layers of mud are deposited, with pebbles and gravels, dispersed, being released from ice rafts and/or icebergs, as they melt. The facies F1, Pgm, Pfm and Agm represent a bar deposit remaining from a subglacial channel. Subglacial channels discharge coarse sediments in front of the glacier that can be transported further by turbidity currents forming lenticular or layered deposits interspersed with diamictites; 3) SHALLOW MARINE PLATFORM UNDER THE ACTION OF STORMWAVES (association of facies C) represented by facies F-A1 (shale-laminated sandstone), F1-S (laminated shale interleaved with siltstones), Aco (sandstone with wavy cross bedding truncated by wave), Ap (sandstone with plane-parallel bedding), Apt (sandstone with plane-parallel and tabular cross bedding), Acot (sandstone with wavy truncated wave and tangential cross bedding), Ach (sandstone with hamocky cross bedding), Aptb (sandstone with plane-parallel and cross-tabular bioturbated bedding), Apmo (sandstone with plane-parallel bedding and wavy marks), Amg (massive sandstone with dispersed granules and pebbles) and Pm (massive paraconglomerate). The deposits are characteristic of platform bars with dominant hummocky structures, attesting to the action of storm waves, covered by extensive layers of marine shales deposited during the good weather phase. This facies association predominates in the upper portion of the Pimenteira Formation gradually passing to the deformed sandstones and diamictites of the Cabeças Formation east of the town of Pedro Afonso.
Acesso aberto (Open Access)
Evolução tectono-metamórfica e petrogênese de gnaisses migmatíticos e granitoides mesoarqueanos do Subdomínio Sapucaia (Província Carajás): uma abordagem geocronólogica, isotópica e estrutural
(Universidade Federal do Pará, 2025-05-09) NASCIMENTO, Aline Costa do; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472
The Sapucaia Subdomain, located between the Rio Maria Domain and the Canaã dos Carajás Subdomain, exhibits a Mesoarchean lithostratigraphy that includes greenstone belts, TTG suites, migmatized gneisses, sanukitoids, potassic granites, and "hybrids." This study presents a description of the main migmatitic structures of the basement within this subdomain and proposes the individualization of the Caracol, Colorado, Água Azul and São Carlos orthogneisses, grouping them into the Caracol Gneiss-Migmatitic Complex. Intruding this complex and the Sapucaia greenstone belt sequence, the Água Fria Trondhjemite represents a second generation of sodic magmatism, along with the Mg-rich granodiorites of the Água Limpa Sanukitoid Suite and the Xinguara Potassic Granite. The migmatites exhibit features indicative of in situ and in-source syn-anatectic melting, characterized by stromatic metatexites, net-structured metatexites, schollen, schlieren diatexites, and rare occurrences of patch metatexites. The paleosome is composed of orthogneiss and amphibolite, while the leucosome is quartz-feldspathic and the melanosome is biotite-rich. The unsegregated neosome is represented by a fine-grained granodiorite. Anatexis occurred under upper amphibolite-facies conditions (~650–700°C). The orthogneisses of the Caracol Complex are metagranitoids with high SiO2 and Na2O contents, low MgO, and strong REE fractionation. The sanukitoids of the Água Limpa Suite follow a calc-alkaline trend, enriched in Mg, Ni, Cr, and LILEs. Despite being younger, the Água Fria Trondhjemite exhibits geochemical affinity with the gneisses but with higher K2O content. The Xinguara Granite is calc-alkaline, rich in SiO2 and K2O, with pronounced negative Eu anomalies, indicating a crustal origin. Geochronological data indicate protolith crystallization of the gneisses between 2.95–2.93 Ga, with regional metamorphism between 2.89–2.84 Ga, coeval with the granulites of the Carajás Province. The sanukitoids of the Água Limpa Suite and the Água Fria Trondhjemite date to 2.87 Ga, followed by the Xinguara Granite at 2.86 Ga. Isotopic data from the orthogneisses reveal positive ƐHf(t) and ƐNd(t) values (+0.65 to +3.9), with Hf-TDM C and Nd-TDM model ages between 3.21 to 2.98 Ga, suggesting a juvenile source. The sanukitoids show ƐHf(t) and ƐNd(t) values ranging from –3.31 to +1.76, model ages from 3.28 to 2.91 Ga, δ18O values between 5.0 and 7.6‰, and feldspar Pb compositions with μ > 10, indicating a mantle source contaminated by crustal material. The Água Fria Trondhjemite exhibits ƐHf(t) and ƐNd(t) values ranging from +1.14 to +3.59, with Hf-TDM C model ages of 3.05 to 3.21 Ga. The Xinguara Granite has a Nd-TDM model age of 2.94 to 2.86 Ga, with ƐNd(t) values between +1.32 and +2.55. The temporal proximity between mantle extraction and the crystallization age of these granitoids suggests a rapid crustal growth process in the region. Geochemical data indicate that the melt responsible for the high (La/Yb)N ratio gneiss group derived from the melting of non-enriched metabasalts, previously transformed into garnet-amphibolite. Sources compositionally similar to the average Archean metabasalts from the Sapucaia and Identidade Greenstone Belts could generate such melts, though at different degrees of partial melting (25–30% or 10–15%). The low (La/Yb)N ratio gneiss-forming melt could also be derived from a similar source but without garnet. The sanukitoid melt resulted from 19–20% partial melting of a mantle source enriched by 32% of a TTG-like melt within the garnet stability field. The Água Fria Trondhjemite formed from 5–10% partial melting of metabasalts, whereas the Xinguara Granite resulted from different degrees of melting of sources similar to the older gneisses. Experimental petrology suggests that the sanukitoids crystallized at 1000–970°C in the liquidus stage and 700°C in the solidus stage, with crystallization pressures of 900–600 MPa and emplacement pressures of 200–100 MPa. These rocks exhibit mineralogy indicative of crystallization under oxidizing conditions (NNO +0.3 to +2.5) and high-water content (H₂Omelt > 6–7%). The Mesoarchean evolution of the Sapucaia Subdomain occurred in three main phases: (1) >3.0 Ga, formation of the primitive felsic crust; (2) between 2.95–2.92 Ga, formation of the Caracol Complex gneisses; (3) 2.89–2.84 Ga, crustal thickening during sinistral transpressive tectonic associated with exhumation and metamorphism of the TTG basement. Crustal stabilization allowed for the formation of younger sanukitoid and TTG magmas (Água Fria Trondhjemite). The ascent of these magmas supplied heat for the melting of regional basement metagranitoids, leading to the formation of anatectic granites. During this stage, gneissic foliation was obliterated by deformation and intrusion of younger granitoids. The integration of the data suggests that tectonic processes facilitated the generation of both crustal and mantle-derived magmas at the end of the Mesoarchean in the Sapucaia Subdomain. It can be inferred that crustal growth in the Sapucaia Subdomain was initially controlled by mantle plumes associated with vertical tectonics, similar to observations in the Pilbara and Dharwar cratons. However, unlike the Rio Maria Domain, the dome-like structuring of the gneissic basement in this subdomain was intensely obliterated by the action of sinistral transpressive tectonics (non-coaxial deformation), forming sigmoidal bodies with an E-W orientation.
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Geologia e Metalogênese do Depósito Au-Ag (Pb-Zn) do Coringa, Sudeste Província Mineral Tapajós, Pará.
(Universidade Federal do Pará, 2020-09-16) GUIMARÃES, Stella Bijos; KLEIN, Evandro Luiz; http://lattes.cnpq.br/0464969547546706; https://orcid.org/0000-0003-4598-9249
The Tapajós Mineral Province (TMP) is located in the south-central portion of the Amazonian Craton and is considered one of the main metallogenic provinces of Brazil. A significant part of the province comprises felsic volcanic and volcanoclastic rocks and granites, which formed predominantly in two intervals, 2.02 to 1.95 Ga and 1.91 to 1.87 Ga, belonging to several stratigraphic and lithodemic units. Fieldwork, petrography, and high-resolution airborne geophysics allowed us to produce a new map at the 1:100,000 scale for the southeastern portion of the TMP, where the gold and silver (Cu-Pb-Zn) Coringa deposit is located. We identified two new geological units: (1) the volcanic and pyroclastic rocks of the Vila Riozinho Formation, previously attributed to the Iriri Group, including a facies defined here of this formation, which comprises a group of rocks with the largest magnetic content in the region (Vila Riozinho Formation - magnetic pyroclastic facies), and (2) the Serra Alkali Feldspar Granite, which intruded into the Vila Riozinho Formation (VRF). These units are the host rocks of Coringa deposit. The FVR rocks represent a magmatic arc with high K calcalkaline to shoshonitic affinities. There are similarities in the patterns of LILE and HFSE and the multielementar diagrams with the granitic rocks from Creporizão Intrusive Suite (CIS). The contemporaneousness between these units reinforce a possible petrogenetic correlation and converge to the hypothesis of similar sources, of probable remelting of arc rocks. Isotopic data revealed similar behavior between VRF, SAFG and Maloquinha Intrusive Suite expose similar behavior and present negative εNd values; however, it indicates rocks derived from enriched sources (ancient crustal rocks). Therefore these units had the same source during tectonic setting and crustal evolution of TMP. It is a transcurrent post-collisional stage that followed the collision of the Cuiú-Cuiú Magmatic Arc related to the Orosian volcano-plutonic event (2033-2005 Ma). Based on available geochronological information these units can be associated with a volcano-plutonic event that occurred in the Orosirian period, at about 1.98 Ga. The Au-Ag (Cu-Pb-Zn) Coringa deposit, occurs essentially in veins and veinlets whose match the regional trend (NNW-SSE). The host rocks are volcanic and pyroclastic rocks of the Magnetic Pyroclastic Facies (MPF) from the Vila Riozinho Formation (ignimbrites, tuffs, and breccia), and the Serra Alkali Feldspar Granite, with a predominance of the supracrustal rocks The hydrothermal processes affected all lithotypes associated with mineralization, producing distal alteration (carbonate-chlorite-epidote), intermediate-proximal alteration (sericite-pyrite) and proximal alteration (chlorite-hematite). The mineralized veins are generally composed of quartz + pyrite + chalcopyrite + galena + sphalerite + electrum + chlorite + sericite. Gold grains occur as inclusions or fractures in pyrite. The fluids presents low salinity, rich in H2O and poor in CO2, with evidence of mixing (magmatic-meteoric), and the presence of adularia and Mn-carbonate are outstanding features of this deposit. All characteristic converge to confirm an intermediate- sulfidation epithermal deposit as a genetic model to Coringa deposit.
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Geoquímica e geocronologia U-Pb shrimp dos granitóides TTG da área de Ourilândia-Tucumã, Província Carajás-SE do cráton amazônico.
(Universidade Federal do Pará, 2023-11-17) REIS, Yury Haresson da Costa; OLIVEIRA, Davis Carvalho de
The rocks that make up the TTG crust in the northern area of Ourilândia do Norte - Tucumã are predominantly tonalitic and show strong petrographic and geochemical affinities with other TTG occurrences in the Carajás Province, which occur in the Rio Maria Domain and Carajás Domain. The granitoids were differentiated based on the occurrence domains of rocks from the Xingu Complex. They exhibit a varied structural pattern, with a tendency towards N-S and concentric patterns. These granitoids are predominantly composed of tonalites with subordinate trondhjemites and granodiorites. The U-Pb zircon crystallization age obtained from the tonalitic variety was 3.00 Ga. The trondhjemites are characterized by higher sodium concentration (Na2O/K2O ratio between 4.24-7.89) and low content of ferromagnesian elements (6 < FeO* + Mg + TiO2 + MnO < 8), while tonalites show sodium depletion (Na2O/K2O ratio between 1.79-3.20) and tend to be enriched in ferromagnesian elements (8 < FeO* + Mg + TiO2 + MnO < 13), with some samples falling within the field of hybrid granitoids, and they are also metaperaluminous (A/NK 1.5-2.0; A/CNK ~1). The Archean is characterized by developing thick sequences of greenstone and TTG plutons, forming dome-like structures and ridges in some cratons, such as those reported in the eastern Pilbara (Australia) and Dharwar (India) cratons. In the model adopted for the Ourilândia-Tucumã area, the generation of the initial stages of TTG magma in the Carajás Province sourced from metabasalts of the Tucumã-Gradaús Group's greenstone belt sequence. This occurred in a scenario involving the partial melting of the base of a thickened mafic oceanic protocrust due to interactions between the lithosphere and convective currents in the asthenospheric mantle, resulting in high-ETRP TTG melt. Dispersed crustal drips formed under increasing pressure and temperature conditions in this context. The partial melting of metabasalt within these drips produced felsic melts that intruded the overlying crust, forming low-ETRP TTG.
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Intemperismo tropical em fachadas azulejadas de edificacoes historicas em belem do para
(Universidade Federal do Pará, 2007-05-14) SANJAD, Thais Alessandra Bastos Caminha; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The application of European tiles on building façades of Belém city started since 19th century. After hundred years under weathering action, the tiles started to show alterations. To understand these weathering action two historical buildings of the 19th century were studied: Palacete Pinho and Solar do Barão de Guajará, located on Belém old town. The Palacete building has German tiles (PPA and PPA-C) and Portuguese tiles from Porto city (PPP). The Solar building has only Portuguese tiles on its main façade, from Porto city (BGFP). Dark stains are the main kind of alteration found in the German tiles. They are located between the glaze and the ceramic part, without lost of glaze. In case of the Portuguese tiles from both buildings, the lost of glaze is frequent, besides the presence of green stains under the detached glaze. Physical characterization results are as follow: 1) the German tiles (PPA and PPA-C) have a lower accessible porosity (12.96% and 9.59%, respectively) and higher density (1.99 g/cm3 and 1.92g/cm3, respectively), than the Portuguese ones (PPP: 29.34% and 1.59 g/cm3 and BGFP: 17.53% and 1.74 g/cm3); 2) the Portuguese tiles present glaze thickness between 0.06-0.1 mm (PPP) and 0.5-0.54 (BGFP) and the German ones between 0.04-0.2 mm (PPA and PPA-C); 3) Portuguese glazes exhibit an abrupt contact with the ceramic part while German tiles show a transition zone between these two layers. Mineralogical analyses of the ceramic parts were carried out using XRD and SEM/EDS. The main mineral phases identified are: quartz, mullite, and cristobalite (German tiles) and quartz, gehlenite, diopside and calcite (Portuguese tiles). Quartz, cassiterite and apatite were also found in both German and Portuguese glazes; only the PPP sample does not have cassiterite. Total chemical analyses of the ceramic parts of German tiles indicated a major amount of SiO2 (75%) and Al2O3 (18%). In the Portuguese tiles, besides SiO2 (46%) and Al2O3 (15%), there is also high CaO contents (22%). Concerning the glazes, the chemical composition is mainly composed by Si and Pb. The green and dark stains beneath the glaze are related to microorganisms of the Cyanophyta and Bacillariophyta divisions. Climatic data records from Belém city were recovered since 1898 and showed that no significant climate changes happened in the region. Rain water sampling and analysis were also carried out in the vicinities of the two studied buildings. 11 The results show small Ca concentrations above regular levels for rain water, which can be related to the mortars. The temperature measurements on tile surfaces indicate variations for different parts of the façades. In the Solar Building, areas of high surface temperature are those where the glaze was unattached to the ceramic bodies. The results showed that the tiles are rather resistance to the tropical weathering. German tiles have a minor glaze lost because of the interface zone between glaze and ceramic part. The absence of such zone in the Portuguese tiles turn then more prone to weathering due to climate changes, mainly thermal daily variations, which lead to glaze detachment.
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lndicadores de estabilidade da matéria orgânica em terras pretas nos sítios arqueológicos Jabuti e Jacarequara (Pará)
(Universidade Federal do Pará, 2015-09-02) SENA, Luciana Freitas de; KERN, Dirse Clara; http://lattes.cnpq.br/8351785832221386; 8351785832221386; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008; 1829861620854008
Environmental conditions in the Amazon region favor the weathering and decomposition of soil organic matter, making it depleted in nutrients and difficult agricultural use. But in the same region, areas that have been modified by human action preterit, known as Terra Preta Archaeological (TPA), have different properties, among which stands out the high stability of soil organic matter (SOM) that in some research it is attributed to interactions between the MOS and other soil constituents such as pyrogenic carbon and minerals from the soil. In this study were selected two archaeological sites in the state of Pará, the Jabuti, the cemetery housing type, located in the city of Bragança, and the Jacarequara, the sambaqui type, located in Barcarena, in order to assess the stability of organic matter TPA from soil extracted solutions (depths 30 and 80 cm) and own soil (collected during the implementation of extractors in December 2013) in areas of TPA and vicinity. The characterization of soil solutions was conducted in the period between March and June 2013, based on the macroscopic properties and the chemical indicators: dissolved carbon concentrations (organic, inorganic and total), determined by the combustion method; pH, Eh and conductivity. The SOM stability assessments in the solid phases of the TPA and surrounding areas (ADJ) were based on textural verification of soil chemical indicators (pH, organic carbon concentrations and Ca, K, P, Na, and Mg) and biological represented by the microbial biomass, determined by the method of irradiation / extraction and expressed in terms of carbon (Cbm) and nitrogen (Nbm). The results of the soil solutions showed that two sites in the pH values are higher in depth (80 cm), and at the site Jacarequara values were determined for this parameter up to 7.2, while the site Jabuti pH results do not exceed the value 6. The maximum values of Eh (mV), conductivity (μs) and dissolved organic carbon (mg L-1) in place Jacarequara, 30 cm deep were respectively +201 mV, 427 µs e 13 mg L-1 and in the area adjacent to this site, at the same depth the highest values were +128 mV, 72 µs e 23 mg L-1 for the same parameters. At the Jabuti site and its ADJ, in 30 cm deep, the respective maximum values of the same areas were Eh +108 mV and +96 mV; conductivity 138.87µs and 59.85µs, dissolved organic carbon 12 mg L-1 and 21.08 mg L-1. Comparing the areas of TPA and their ADJ, the data Eh and dissolved organic carbon refer to more stable components in soil areas of solutions of TPA, owing to the more oxidizing values and smaller dissolved organic carbon concentrations, the results conductivity, which is an indicator of the concentration of ions is higher in the TPA reporting the increased availability of nutrients. In both sites, soils presented sandy texture, both in the areas of TPA as the ADJ, the latter being more sandy. In the soil Jacarequara site and its ADJ in the range of 20 to 30 cm deep, the following values were obtained respectively: 119.82 g kg-1 and 20.34 g kg-1 for SOM; pHH2O equal to 6.8 and 4.9; 183 mg/dm3 and 5 mg/dm3 P (available); 39 mg/dm3 and 29 mg/dm3 K (exchangeable); 14.8 cmolc/dm3 and 0.7 cmolc/dm3 Ca (exchangeable); 0.1 cmolc/dm3 and 1.7 cmolc/dm3 Al (exchangeable), 181.26 μg g-1 and 88.74 μg g-1 of Cbm and 3.27 mg kg-1 and 1.91 mg kg-1 Nbm. In the soil of Jabuti site, the determined values were: 83.66 g kg-1 of MOS, pHH2O equal to 4.4; 55 mg/dm3 P (available); 59 mg/dm3 K (exchangeable); 0.3 cmolc/dm3 Ca (exchangeable); 4 cmolc/dm3 of Al (exchangeable); 92.56 mg kg-1 of Cbm and 1.41 mg kg-1 Nbm; in the area adjacent to this site, the values were: 13.13 g kg-1 of MOS, pHH2O equal to 4.6; 4 mg/dm3 P (available); 29 mg dm3 K (exchangeable); 0.3 cmolc/dm3 Ca (exchangeable); 1 cmolc/dm3 Al (exchangeable), 27.54 mg kg-1 of Cbm and 0.96 mg kg-1 Nbm. As well as other archaeological sites with TPA, Jacarequara and the Jabuti had significantly higher levels of nutrients compared to surrounding areas, with the exception of Ca element in Jabuti. In the sites, carbonaceous particles were investigated, showing no intrinsic results pyrogenic carbon. In areas of TPA, the results obtained from the soil analysis indicated positive correlation between the microbial biomass, organic matter and nutrients, which can be associated with better quality of the soil in these areas compared their ADJ, consistently with the data highlighted in the soil solutions. Comparing the two sites, the results indicate that the SOM in Jacarequara site shows more stable constituents.
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Materiais construtivos e sua biodeterioração em fortificações da Amazônia
(Universidade Federal do Pará, 2017-03-29) NORAT, Roseane da Conceição Costa; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
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Metalogênese do depósito aurífero Volta Grande, Domínio Bacajá (PA), Cráton Amazônico: aplicação de espectroscopia de infravermelho VNIR-SWIR.
(Universidade Federal do Pará, 2024-02-27) PARESQUI, Brenda Gomes Silva; FERNANDES, Carlos Marcello Dias; http://lattes.cnpq.br/0614680098407362; https://orcid.org/0000-0001-5799-2694
The world-class Volta Grande gold deposit contains measured reserves of ~6.0 Moz at 1.02 g/t, divided into north and south exploration blocks. It is inserted in the geological context of the Bacajá Domain and was affected by the Trans-Amazonian Cycle (2.26–1.95 Ga). Part of the mineralization is hosted in a group of gneisses and mylonitized granitoids in amphibolite facies of medium to high metamorphic grade of the Três Palmeiras Group (2.36 Ga). Recent research in the northern block has revealed the presence of late volcanics and plutonics, with isotropic texture and intermediate to felsic compositions, which host disseminated gold in different types and styles of hydrothermal alteration, as well as in quartz and carbonate (±sulfides) venules and veins. Thus, this Master's Thesis represents the continuity of research in the northern block of this repository with the application of the VNIR–SWIR (visible-near and short-wave infrared) infrared spectroscopy technique. This tool helps to explain in detail the configuration of the hydrothermal system, contributing to a better understanding of the genesis of the deposit. The mineralogy observed by spectroscopy in metamorphic rocks confirms the occurrence of potassic, propylitic, intermediate argillic, pervasive carbonate, and advanced argillic hydrothermal alterations types. The latter occurs associated with high levels of gold and alunite, a mineral indicative of epithermal systems with high-sulfidation. In turn, the isotropic volcanic and plutonic rocks present more developed, intense, and larger-volume hydrothermal alterations. They reveal greater diversification of hydrothermal minerals, where jarosite is the superior indicator of advanced clay alteration, which is also consistent with high-sulfidation epithermal mineralizations. In addition, the appearance of rhodochrosite, pyroxmangite, and galena, mainly related to volcanic rocks of andesitic and dacitic compositions, suggests an epithermal system of intermediate-sulfidation. The geological features present in the region and the hydrothermal alterations, especially the propylitic alteration in the rocks with allanite, clay minerals, montmorillonite, and zeolites, portray a typical epidote subzone of a low-temperature propylitic alteration that are genetically related to the medium-depth intrusions where they appear hydrated porphyry stocks. In this way, the Volta Grande gold deposit reveals characteristics compatible with rare and base metals porphyry and epithermal mineralizing systems, already identified in other regions of the Amazon Craton. The high-sulfidation conditions at the northwest portion of this repository and intermediate-sulfidation at the southeast region point to a transitional environment. The VNIR–SWIR spectroscopy method represents an important tool that identifies and characterizes hydrothermal minerals quickly and efficiently, as well as differentiating them from weathered ones. In general, it becomes a significant prospective guide when robustly analyzing minerals that are difficult to recognize by other methods such as conventional optical microscope or scanning electron microscope (SEM). The results presented here represent a remarkable contribution to the geological and metallogenetic knowledge of the Bacajá Domain, as well as the Amazonian Craton as a whole, pointing out the potential for identifying economically viable deposits of precious and base metals associated with volcanic and plutonic systems that occur in a vast area of this domain.
Acesso aberto (Open Access)
Morfologia e composição de rutilo como guia prospectivo para depósitos de Au: o exemplo do depósito São Jorge, Província Mineral do Tapajós
(Universidade Federal do Pará, 2025-03-18) MEDEIROS, Marcos Flávio Costa; LAMARÃO, Claudio Nery; http://lattes.cnpq.br/6973820663339281; https://orcid.org/0000-0002-0672-3977
The Tapajós Mineral Province (PMT), inserted in the context of the Tapajós-Parima or Ventuari-Tapajós geochronological province, is recognized as the largest gold-bearing province in Brazil. The São Jorge Jovem Granite (GSJJ), located east of the PMT in a heavily fractured and hydrothermalized area, hosts gold mineralization. The GSJJ exhibits calcium-alkaline affiliation K-rich, composed of rocks of monzogranitic and leucomonzogranitic composition, with amphibole and biotite as the main mafic minerals. Pb-Pb dating of zircon in leucomonzogranites revealed a crystallization age of 1891±3 Ma. TiO2 polymorphs are common accessory phases in several types of rocks. In nature, it occurs in three main polymorphs: anatase and brookite, which are representatives of low temperatures and pressures, and rutile, at medium to high and ultra-high pressures and temperatures. Of these, rutile is the most common polymorph in the Earth's crust. The samples and polished blades used in this research come from drilling holes carried out by Rio Tinto Desenvolvimento Minerais (RTZ) in GSJJ. TiO2 polymorphs are represented by thin (10-100μm) anhedral crystals in or surrounding biotite. Samples from the mineralized zone show varied hydrothermal alteration, with rocks in the propylitic and phyllic alteration stages. TiO2 polymorphs form acicular aggregates or aggregates with a skeletal texture, predominantly replacing titanite. Spot electron microprobe analyses conducted on individual crystals and aggregates of rutile crystals revealed significant compositional variations, particularly concerning the contents of Nb, Al, Zr, V, and W. Rutile crystals from the non-mineralized zone (NMZ) exhibited higher levels of Nb (> 5,000 ppm) compared to crystals from the mineralized zone (MZ; predominantly < 3,000 ppm). Rutile crystals from the MZ display a trend of Al enrichment and V. Crystals from the NMZ sometimes show enrichment in Fe but are always accompanied by levels considered to be Nb. ZM crystals exhibit a trend of enrichment in W, V, and Sb and are always depleted in Nb. Analysis of rutiles demonstrates that their chemical composition can be used to distinguish between mineralized rocks and other types of non-mineralized rocks. The results indicate that the trace element composition of rutile, mainly the V content, and other elements such as Al, Zr, Sb, W, offer the best indications of mineralization in gold deposits.
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Origem e evolução do complexo granitoide neoarqueano de vila Jussara: implicações para a evolução crustal da província Carajás
(Universidade Federal do Pará, 2022-07-15) SILVA, Fernando Fernandes da; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472
New information on the geology, combined with the acquisition of geochemical and isotopic data (U-Pb, Hf and Nd) from the Vila Jussara Suite, are presented in order to discuss a petrogenetic model for the Neoarchean granitoids of the Carajás Province. This suite appears as a series of coalescing plutons with sigmoidal and elongated shapes, in the E-W direction, which follow the regional trend. The central areas of the plutons are slightly deformed, while the marginal portions have a mylonitic appearance and are delimited by sinistral shear zones belonging to the transcurrent system of the Itacaiúnas Shear Belt. These granitoids present a broad compositional spectrum, with four individualized lithotypes: (i) biotite-hornblende serial monzogranite, which is subdivided into oxidized and reduced types; (ii) biotitehornblende tonalite; (iii) biotite monzogranite; and (iv) porphyritic granite (hornblende biotite monzogranite/granodiorite). The geochronological data U-Pb and Pb-Pb in zircon provided an age of crystallization of 2.74 Ga for the granitic and porphyritic granite varieties, and for the biotite-hornblende tonalite variety, an age of 2.76 Ga. The isotopic data of Nd and Hf suggest that the magmas of the Vila Jussara suite are not juveniles [εNd (-3.5 to 1.5) and εHf (-1.2 to 3.5)] and were derived from rocks of Mesoarchean age (TDM > 3.0 Ga). The petrogenetic model adopted to generate the primary magmas of this suite admits as source rock the Mesoarchean granulites from the Ouro Verde area of the Canaã dos Carajás subdomain. Field relationships, geochemical and isotopic data suggest that the granitoids that make up the Vila Jussara Suite are not formed from a single parental magma, but by multiple magma injections generating extensive hybridization. Its magmas were placed along pre-existing structures under a transtensional tectonic regime dominated by pure shear in a post-collisional syntectonic context.
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Petrogênese da Suíte Igarapé Gelado: implicações para o magmatismo neoarqueano da Província Carajás, Cráton Amazônico
(Universidade Federal do Pará, 2025-04-30) MESQUITA, Caio José Soares; DALL’ AGNOL, Roberto; http://lattes.cnpq.br/2158196443144675
The Igarapé Gelado suite (IGS) is located near the northern border of the Carajás Province, almost at its boundary with the Bacajá Domain, along the Cinzento lineament, and is intrusive in metavolcanic mafic rocks and banded iron formations. The central-eastern portion of the IGS comprises four rock varieties: tonalite to granodiorite with varying contents of biotite and amphibole, (1) with associated clinopyroxene and/or orthopyroxene (PBHTnGd) or (2) devoid of pyroxenes (BHTnGd); and monzogranites that exhibit variable biotite and amphibole content and can be (3) moderately (BHMzG) or (4) strongly (RBHMzG) reduced. The PBHTnGd shows ferrosilite and/or augite with subordinate hedenbergite. The amphiboles are K-hastingsite and, subordinately, Fe-Tschermakite in monzogranites. Biotites are ferroan, and in reduced granites show #Fe > 0.90. These micas are similar to those of alkaline to subalkaline rocks and compositionally akin of primary magmatic biotites. Plagioclase is oligoclase. The integration of thermineral chemistry;mobarometry results and thermodynamic modeling and their comparison with the paragenesis present in natural rocks improved the estimation of crystallization parameters (T, P, ƒO2, H2O), and allowed a better interpretation of magmatic evolution. The IGS granites crystallized at pressures of 550 ± 100 MPa, higher than those attributed to other Neoarchean granites in Carajás provinve. The estimated liquidus temperature for the IGS pyroxene variety is ~1000±50°C. BHTnGd and BHMzG formed within a similar temperature range to PBHTnGd, while RBHMzG had lower liquidus temperatures (≤900°C). Solidus temperatures of around ~660 °C were estimated for the four IGS varieties. The BHMzG magma evolved under conditions of low ƒO2, slightly above or below the FMQ buffer (FMQ±0.5), like those of the Planalto suite and the reduced granites of the Vila Jussara and Vila União suites of Carajás province. In the magmas of the PBHTnGd and BHTnGd varieties the oxygen fugacity attained FMQ+0.5. The RBHMzG crystallized under strongly reduced conditions equivalent to FMQ-0.5 to FMQ-1. The magmas of the monzogranitic varieties evolved with a H2O content of ≥4 wt%, attaining 7 wt% in the case of the reduced monzogranites. This is comparable to, or slightly exceeding, the levels typically attributed to the Neoarchean granites of Carajás province (≥ 4% wt%). In contrast, the variety with pyroxene has a water content (~4 wt%) like that of Café enderbite and Rio Seco charnockite from Carajás province, and Matok Pluton from Limpopo belt. Based on the chemical composition, the rocks from IGS are ferroan, reduced to oxidized A-type-like granites, akin to other Neoarchean granite suites from the Carajás province. The IGS are younger than the 2.76-2.73 Ga Neoarchean granites from the Carajás province. A crystallization concordia age of ~2.68 Ga was obtained by U-Pb SHRIMP in zircon for the RBHMzG variety, and similar upper intercept ages were furnished by the other IGS varieties, except for ages of ~2.5 Ga that resemble the ages of the IOCG Salobo deposits associated with reactivation of the Cinzento Lineament. Tmineral chemistry;he deformation of the IGS rocks was influenced by shear zones linked to that lineament, forming elongated bodies with varied foliation. These zones facilitated the migration and deformation of magmas from the final crystallization stages until their complete cooling, characterizing a syntectonic process. This syntectonicity is associated with the inversion of the Carajás Basin, and the younger crystallization age of these rocks indicates that the inversion occurred up to 2.68 Ga, extending the previously estimated interval (2.76– 2.73 Ga). The IGS displays negative to slightly positive values of εNd(t)(-2.86 to 0.18) and εHf(t)(-3.3 to 0.1), and Paleoarchean to Mesoarchean TDM ages [Nd-TDM(2.98-2.84) and Hf-TDM C (3.27-3.12)]. The positive values of εNd(t) and εHf(t) for the RBHMzG variety, suggest possible juvenile contribution or contamination in the source of its magma. The IGS rocks come from the melting of 19% (PBHTnGd) or 14% (BHTnGd) of contaminated mafic granulite, - and from melting of 9% (BHMzG) and 7% (RBHMzG) of a tholeiitic mafic granulite. The area of occurrence of the IGS is marked by hydrothermalism and mineralizations that locally modified the composition of rocks and minerals, allowing the leaching of REE and Y that changed the composition of some samples of BHMzG approaching them of (false) A1- subtype granites. In addition, these processes were responsible for zircon alteration, which resulted in grains showing enrichment of U, Th, and LREE, and massive textures, that furnished upper intercept U-Pb ages, contrarily to the zircon crystals of the RBHMzG variety that preserved primary characteristics and presented Concordia ages.
Acesso aberto (Open Access)
Petrogênese dos granitos Manda Saia e Marajoara: contribuições para a definição da natureza do magmatismo paleoproterozóico da Província Carajás.
(Universidade Federal do Pará, 2024-12-13) SANTOS, Rodrigo Fabiano Silva; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472
The Marajoara (MJG) and Manda Saia (MSG) granites are located in southeastern Pará State, Brazil, and represent circular intrusions with stock dimensions embedded in Mesoarchean rocks of the Rio Maria Domain, in the central-southern portion of the Carajás Province. These rocks outcrop as extensive pavements, exhibiting no solid-state deformation features (isotropic aspect) and frequently containing angular enclaves of the surrounding host rocks. The MJG comprises equigranular biotite monzogranite (eBMzG) and heterogranular (hBMzG) varieties, as well as porphyritic (pME) and microgranular enclaves (ME) restricted to the hBMzG facies. Quartz content and plagioclase/microcline ratios vary significantly, allowing these rocks to be classified from syenogranitic to monzogranitic, and even granodioritic in the case of microgranular enclaves. They are peraluminous granites, similar to ferroan granites with high K2O+Na2O/CaO and FeOt/(FeOt+MgO) ratios, enriched in Rb, Zr, Y, Nb, F, and heavy REEs, with more evolved facies displaying low Sr and Ba contents. In REE patterns, negative Eu anomalies are prominent, and heavy REEs show a gradual increase with magmatic differentiation. These granites fall within the intraplate granite field and exhibit geochemical affinities with A-type granites. Their FeOt/(FeOt+MgO) ratios align with typical oxidized (hBMzG and pME) and reduced (eBMzG) A-type granites, while the MSG displays a moderately reduced character. The ME, however, show affinity with magnesian and calcalkaline series granites. According to biotite mineral chemistry, MSG and the hBMzG facies of MJG fall within the magnetite series field, while eBMzG rocks are similar to ilmenite series rocks. SHRIMP zircon U–Pb analyses provide crystallization ages of 1884 ± 11 Ma for MJG and 1866 ± 10 Ma for MSG (LA–SF–ICP–MS). Lu–Hf isotopic data indicate ƐHf(t) between - 11 and -18 and Hf-TDMC from 3.2 to 3.6 Ga for MJG; and ƐHf(t) between -13 and -19 and Hf-TDMC from 3.3 to 3.6 Ga for MSG. The compositional gaps among the various MJG varieties suggest that their magmas are not cogenetic. Geochemical modeling suggests that MJG and MSG were generated by partial melting of tonalitic rocks, with occasional metasedimentary contributions, at a melting rate ranging from 16 to 18%, with a residual assemblage of plagioclase, quartz, biotite, magnetite, and ilmenite. Felsic and mafic magma mixing played an important role in the emplacement. The enclaves represent enriched lithospheric mantle-derived magmatism injected into the magma chamber during the subduction process, interacting to varying degrees with the magma forming the Marajoara granite. This hypothesis may be reinforced by the occurrence of a 1.88 Ga diabase-porphyritic granite composite dyke in the Rio Maria region. The proposed model suggests that the granitic magma initially formed a magma chamber, followed by repeated mafic magma injections, resulting in small-scale convection. Subsequently, large volumes of hot mafic magma entered the chamber, leading to mixing processes. Microgranular and porphyritic enclaves were formed due to magma mixing in areas where there were temperature contrasts between felsic and mafic magmas. The results presented in this study highlight the importance of the Archean crust in the origin of Paleoproterozoic granites, which were emplaced in shallow crustal levels through a dyke feeder system as a result of extensional tectonics.
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Petrografia e geoquímica do Granito Manda Saia, Província Carajás.
(Universidade Federal do Pará, 2020-09-09) SANTOS, Marcelo Reis; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; 0294264745783506
The Manda Saia granite is located to southeast of the of Xinguara town and it is represented by two semicircular plutons separated by the Mesoarquean basement of the Rio Maria Domain. The bodies crosscut in the northern portion the Mesoarquean TTG granitoids and the Rio Maria Granodiorite, and in the south, eastern and western portions they are intrusive in the metabasalts of the sequence greenstone belt of the Babaçu Group. The Manda Saia pluton is formed by rocks of isotropic aspect, grayish pink in color and monotonous textural variation. They are hololeucocratic rocks of medium-to-coarse heterogranular texture, occasionally porphyritic, which are classified as monzo- and syenogranites. Biotite is the main ferromagnesian mineral and amphibole is rare and interstitial. Secondary minerals are clay minerals, sericite, muscovite, fluorite and chlorite. Manda Saia pluton is formed by peraluminous rocks that present a restricted and high SiO2 contents (74.80 and 77.70wt.%), and high Fe/(Fe+Mg) ratios. Their REE pattern is marked by enrichment in light and heavy REE and moderate negative Eu anomaly. The pluton can be classified as ferrous type-A granite and akin to the reduced types and those most evolved from the oxidized granites of the Carajás Province. The occurrence of interstitial amphibole identified in the Manda Saia granite also is observed in the plutons of the Velho Guilherme Suite. On the other hand, the frequent occurrence of magnetite combined with the compositional aspects of its rocks, also shows that the Manda Saia granite is akin to the leucogranitic facies of the oxidized granites from Jamon Suite. The emplacement of the Granite Manda Saia is linked to extensional tectonics and the transport of magma that resulted in the emplacement of the plutons in shallow crustal levels (~ 1.0 ± 0.5 kbar) through a dyke feeding system.
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Petrografia e mineralogia das alterações hidrotermais associadas ao bloco Sul do depósito aurífero Volta Grande do Xingu, Domínio Bacajá (PA), Cráton Amazônico
(Universidade Federal do Pará, 2025-04-22) PINTO, BRENDA THAYS BARROS; FERNADES, Carlos Marcello Dias; http://lattes.cnpq.br/0614680098407362; https://orcid.org/0000-0001-5799-2694
The world-class Volta Grande gold deposit, at the Bacajá Domain, contains measured reserves of approximately 6.0 Moz at 1.02 g/t, divided into the north and south exploratory blocks. Historically, this mineralization has been classified as orogenic (lode-type) and is found within a set of mylonitized granitoids in the amphibolite facies of medium to high metamorphic degree attributed to the Três Palmeiras Group (2.41 Ga) and the Oca Granodiorite (2.16 Ga). However, recent research on the rocks of the northern block has established a late volcanic sequence with significant gold mineralization. Aiming to contribute to its metallogenetic modeling, this Master’s Dissertation focused on the southern block, involving macroscopic and microscopic petrographic descriptions and the application of VNIR–SWIR reflectance spectroscopy in core samples from the Pequi, Grande, and Itatá targets. First, the results include the petrography of metamorphic rocks, represented by amphibolite and mylonitic granodiorite, and an associated isotropic volcanic and plutonic suite. The data compilation revealed mineral paragenesis related to metamorphic and magmatic-hydrothermal processes. The metamorphic paragenesis reveals regional and dynamic-thermal metamorphisms and moderate overprinting of hydrothermal alterations typical of epithermal systems, associated with the emplacement of the isotropic rocks package. Second, in the isotropic rocks, there is an overprint of hydrothermal alterations and gold mineralization conceivably of intermediate- and high-sulfidation epithermal-type genetically linked to magmatic-hydrothermal systems, with carbonate alteration in a boiling zone and advanced argillic alteration. In conclusion, data integration from the southern block shows, similarly to the northern block, at least two genetically distinct gold mineralizing events that enhanced the grade and tonnage of the Volta Grande deposit, thus representing a new prospective model for the Bacajá Domain.

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