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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)
Charnoquitos de Ourilândia do Norte (PA): geologia, natureza e implicações tectônicas para a Província Carajás.
(Universidade Federal do Pará, 2019-10-02) FELIX, Williamy Queiroz; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The granite-charnockite association from Carajás Province is spatially associated with gabbronorites, which intrude Mesoarchean granitoids and form a NE-SW elongated pluton with subordinate lenses E-W oriented showing subvertical (70-80°) foliation. They consist of leucocratic rocks (M' = 21.1 - 32.9) with well-preserved magmatic textures and medium- to coarse-grained. The main mafic phases are pyroxene [enstatite/ferrosilite and augite/diopside (Wo1En66Fs33 to Wo49En38Fs14)], amphibole [hornblende (0.88 ≥ Mg/(Mg+Fe2+) ≤ 0.43)], and biotite [0.68 ≥ Fe/(Fe + Mg) ≥ 0.31]. These rocks are considered syntectonic plutons emplaced in a postcollisional setting, which underwent dynamic recrystallization controlled by subgrain rotation (SGR; 400-450 °C) in a sinistral transpressive deformational regime driven by pure shear. The granite-charnockite association and gabbronorite present very similar geochemical behavior: magnesian affinity [whole-rock 0.8 ≥ FeOt/(FeOt+MgO) ≤ 0.5], calc-alkaline and high-K calcic-alkaline trends and metaluminous character. Magma ascent and emplacement are reconstructed as a singlestage process with decreasing temperatures. Crystallization temperatures range from 1100 to ~700 °C for pyroxenes, and 809 to 713 °C for amphiboles. Calculated crystallization pressures were 190 to 310 MPa resulting in crystallization depths of 7.0 to 10.5 km. Observed mineral assemblages and compositions of the main mafic minerals imply crystallization under relatively oxidizing conditions (NNO -9.8 to -12.6). H2O contents ranging from 4.1 to 6.5 wt% and indicates that water played an important role in the magmatic evolution of the studied rocks. Hydration was responsible for differences in the modal contents of monzogranite varieties. Gabbronorites were probably formed by partial melting of depleted mantle source (low HFSE), and orthopyroxene-bearing granitoids originated through fractional crystallization from magma similar in composition to gabbronorite.
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)
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.
Acesso aberto (Open Access)
Geocronologia U-Pb, classificação e aspectos evolutivos do Granito Marajoara – Província Carajás
(Universidade Federal do Pará, 2018-01-24) SANTOS, Rodrigo Fabiano Silva; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The Marajoara granite (MjGr) is a stock intrusive in mesoarchean granitoids of the Rio Maria domain, which is formed mainly by leucocratic rocks, represented by equigranular (BMzE) and heterogranular (BMzH) monzogranite facies. Rapakivi texture and occurrences of porphyritic granite (EGp) and microgranular enclaves (EMg) are restricted to BMzH facies. Such varieties have similar mineralogy: microcline, quartz and plagioclase occur as essential minerals; biotite partially altered to chlorite as the only varietal phase; zircon, titanite, opaque, apatite and allanite as primary accessories; and chlorite, sericite-muscovite, epidote, fluorite and clay minerals as secondary phases. The high magnetic susceptibility (SM) values (2.3-6.5 x10-3) and the frequent presence of magnetite show that the BMzH facies is akin to granites with magnetite series, whereas the BMzE variety shows affinity with the ilmenite series considering the modal opaque contents ≤0.5%, low values of SM (<0.15x10-3), and ilmenite as the sole Fe-Ti oxide. These rocks are, in general, peraluminous and have high FeOt/FeOt+MgO ratio, similar to the ferroan granites. In addition, they have geochemical affinities with intraplate A-type granites, which have crustal origin, wherein a significant variation of FeOt/(FeOt + MgO) found for these rocks [EGp (> 0.82); BMzH (> 0.86); BMzE (> 0.97)], allow them to be classified as oxidized (BMzH and EGp) and reduced (BMzE) Atype granites, that are related to the Jamon and Velho Guilherme suites, respectively. Differently from this, the EMg show clear affinity with the magnesian granites and the calcalkaline series. Evidence of magma mixing and geochemical modeling calculations demonstrate that EGp originate from the interaction of EMg (60%) and BMzH (40%) liquids. The compositional gaps existing among the several varieties that constitute the MjGr, as well as their compositional contrasts, suggest that their magmas are not cogenetic. The EMg represents a basic magmatism from the enriched lithospheric mantle that would have been injected into the magma chamber during the underplating process and at different phases of the granitic magma crystallization. The U-Pb zircon isotopic analyzes (SHRIMP) yielded an age of 1885 ±6Ma, interpreted as the crystallization age of MjGr. The MjGr was emplaced at shallow crustal levels (epizone) in an extensional tectonic environment with the effort following the trend NNE-SSW to ENE-WSW. The concentric zoning in the MjGr and the rheological behavior of its country rocks as well as the reduced or no influence of the regional efforts during the emplacement of the pluton indicate that the transport of the magma occurred through dikes. It is suggested that the construction of the MjGr was a result of the vertical rise of magmas through fractures and accommodation along the planes of the regional EW foliation, followed by a change of the vertical flow by a lateral scattering of the magma, analogous to the admitted model for the emplacement of the tabular batholiths of the Jamon Suite.
Acesso aberto (Open Access)
Geologia e geoquímica dos granitóides Arqueanos da área de Bannach (PA): uma reavaliação das áreas de ocorrência do trondhjemito mogno e granodiorito Rio Maria
(Universidade Federal do Pará, 2018-08-21) MACHADO, Jean Ricardo Mesquita; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The Bannach area is located in the center-west of Rio Maria Domain, Carajás Province, Amazonian craton. Based on field relationships, petrography and geochemical behavior, it was possible to identify six varieties that was divided into two groups: (i) high silica and low Mg group, represented by trondhjemitic rocks associated with mogno Trondhjemite (TdhMg), leucogranodiorites and fine grained granitoids and (ii) low silica and high Mg groups, represented by biotite granodiorites, amphibole bearing tonalites and biotite tonalites (enclaves). The trondhjemites, leucogranodiorites are the most extensive batholiths of the region, covering approximately 90% of the work area, presenting medium-to-coarse heterogranular texture and E-W to NW-SE ductile deformation features. The biotite granodiorites occur as a small stock in the north-east, being formed by more enriched in mafic minerals rocks than the predominant granodioritic variety. The amphibole bearing tonalites (± quartz diorites) is emplaced along shear zones that intersect the central portion of the area, being more deformed than the other rocks and the only amphibole bearing granitoid. In smaller proportions, the biotite tonalites represent mega-enclaves of the trondhjemitic rocks, whereas the fine granitoids intersect the other rocks of the region. These varieties are divided into two groups. Geochemically, the group of high silica (SiO2> 70%) presents high levels of Al2O3, CaO and Na2O (especially leucogranodiorites) in detriment of Fe2O3, MgO, Ni and Cr. Moreover, these varieties have high La/Yb and Gd/Er ratios, discrete or absent Eu negative anomalies, and strongly fractionated REE patterns. On the other hand, the low silica granitoids present high content of Fe2O3, MgO, Ni and Y, emphasizing the high K- Ba-Sr content of the biotite granodiorites in relation to the other granitoids in the area, in addition to their moderate to high La/Yb ratios, while the other low silica granitoids present low La/Yb ratios because of the high HREE content, which provides a sub-horizontal REE pattern. These differences trace back distinct formation processes for Bannach granitoids. Although the formation of trondhjemites and leucogranodiorites occurs in the garnet stability zone, its chemical differences go back to sensible differences in its magma. The origin of the trondhjemites is associated with the partial melt of garnet amphibolite, under high pressure conditions in a subduction environment. The leucogranodiorites, due to their higher sodium enrichment, Ba and Sr, have their compositional control associated to different degrees of melting of basalt under different pressure levels and by a source richer in subducted sediments of the oceanic crust to produce magmas of similar composition to the leucogranodiorite. Therefore, it is assumed that these rocks would have originated by the fusion of enriched tholeiite basalts installed below an older TTG crust that would have been assimilated by these melts. The geochemical aspects, such as the high LILE content and even high presence of mantle affinity elements (Mg, Ni and Cr) of the biotite granodiorites and amphibole bearing tonalites may denounce their affinities with the rocks of the Sanukitoid suite of Rio Maria. The ambiguous geochemical character of the biotite granodiorites associated with the highest SiO2 content when compared to the quartz diorites, as well as their higher levels of Rb and Ba, Sr, Y and the La/Y and Sr/Y ratios indicate a more evolved and conditions of formation in higher pressure and that has felsic parent magmas, as well as a mafic component acting in its origin, approaching the Closepet-type granites. In this way, these compositional affinities indicate a strong petrogenetic analogy, with an origin from an enriched mantle or even from a mafic source of high-K. On the other hand, the less evolved character of the amphibole tonalites, as well as the low La/Yb and Sr/Y ratios indicate that these have a higher mantle affinity and that formed at low depths. It is assumed that the origin of these rocks would have been from a metassomatized mantle by slab fluids in a subduction environment.
Acesso aberto (Open Access)
Geologia e Geoquímica dos Granitoides Mesoarqueanos da Porção Noroeste do Domínio Rio Maria da Província Carajás: individualização e contexto tectônico das rochas da área de Tucumã.
(Universidade Federal do Pará, 2019-09-16) SILVA, Luana Camile Silva; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The Carajás Province (CP) represents the largest preserved Archaean core of the Amazonian Craton with worldwide correspondents. Thus the Tucumã área, located in the northwest portion of the Rio Maria Domain (RMD) near the tectonic border with the Carajás Domain (CD), is marked by the occurrence of mesoarchean age granitoids. This study deals with the discrimination and characterization of this region granitoids which according to the regional studies is dominated by the Rio Maria suíte, by Xingu Complex rocks and metamafics of the greenstone belts sequences. However since data obtained in this work with geological mapping in detailed scale showed that the geological framework of Tucumã is much more diverse and complex. So that contrary to previous studies the most expressive unit in the region are high-K leucomonzogranites rocks that occur as a large plúton. Associated to this pluton small enclaves of granitoids of various compositions are presente in the form of lenses, controlled by NE-SW and E-W anastomosed shear zones. These bodies distinction led to the recognition of five groups: i) high-K Leucomonzogranite; ii) high-HFSE Granites subdivided into medium- and high-Ba; iii) porphyry médium-K Granodiorite; iv) high-Mg Granodiorite; and v) high-Na Tonalite. The granitoids have affinity with the calc-alkaline series, other than high-Na tonalites which follow the trondhjemitic trend with TTG affinities. The latter refers to magnesian granitoids Na2O rich (low K2O/Na2O ratio) which also differ from the others due to the N-S structural pattern often found in greenstone belt sequence, associated with an older tectonic in the region. The moderately fractionated REE patterns (medium La/Yb and Sr/Y ratios) and absence or small negative Eu anomaly typical of TTGs, are features similar to those of médium La/Yb ratio Mogno trondhjemite. With regard to the calc-alkaline units the porphyry médium-K granodiorites differ from the others by the magnesian feature and higher enrichment in Na2O (médium K2O/Na2O ratio) which set forth a resemblance to the TTG suites. However the médium-K granodiorites have higher levels of Ba, K and Th than TTG composition rocks, indicating strong similarities to the so-called transitional or enriched TTG suites. The small differences in the geochemical pattern of these two units are related to changes in the source, where the TTGs (high-Na tonalites) would be the product of the partial melting of a hydrated mafic source (metabasalts), on the other hand the transitional TTGs (porphyry médium-K granodiorite) would originate from melts of a heterogeneous crust with intercalation of enriched basalts and felsic layers. The high-Mg granodiorites occurs in a restricted way in Tucumã identified only in two outcrops. They are distinctly more enriched in Sr and mantle elements (Mg, Cr and Ni) and impoverished in HREE regarding the other granitoids. These features show strong affinities with the sanukitoides suites (Rio Maria Granodiorite) linked to the partial deep melting of the metassomatized mantle. The high-HFSE Granites (medium- and high-Ba) share geochemical characteristics with both the sanukitoide suite and the high-K leucogranites suíte similar to Hybrid granites like the Closepet-type. These suites represent different degrees of interaction processes (mingling or mixing), in the middle crust between crustal melts (tonalites/metassediments) and enriched mantle differentiated melts. Whilst the high-K leucomonzogranites represent the most evolved rocks in the region, where its enrichment in LILEs (Ba, K and Rb) and presence of the negative Eu anomaly indicates crustal reworking processes of an ancient felsic (tonalitic) crust at intermediate crustal levels. This unit has affinities with tha Xinguara and Mata Surrão granites. Regarding the deformation pattern, the rocks with the highest degree of deformation are the high-Na tonalities, in the other units this pattern is only identified in the portions where the shear zones are located. The observed textures (mantle-core and microcracks textures) suggest the operation of deformation processes during the magma crystallization typical of sintectonic granitoids under high temperature conditions (>500ºC). Less deformed granitoids present evidence of dynamic recrystallization at temperatures below 400°C. Thus, in RMD two phases of magmatism are identified, being the first one (2,98-2,92 Ga) related to a subduction setting under an oceanic plateau or a thickened mafic crust with melting at different crustal levels (crust root and slab), and mantle metassomatization by TTG melts and fluids. The second phase (~2.87 Ga) starts from thermal events (slab breakoff, delamination or mantle plumes) that results in partial meltilng of the metassomatized mantle with production of sanukitoide magmas and hybrid granites. This results in changes of the crustal root thickness that lead to substancial temperature variations sufficient to generate partial melting in and beneath the crust associated to generation of high-K granites.
Acesso aberto (Open Access)
Geologia, geoquímica e geocronologia do granito Boa Sorte, Município de Água Azul do Norte (PA), Província Carajás
(Universidade Federal do Pará, 2013-08-30) RODRIGUES, Daniel Silvestre; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The Boa Sorte granite occurs in the southeastern region of the Pará state, northern Brazil, in the geological context of the Carajás Domain or, more precisely, in the Transition subdomain between the Rio Maria domain and the Carajás basin. It corresponds to an E-W elongated batholith, formed of biotite leucomonzogranites with subordinate granodiorites and syenogranites, with varying degrees of deformation. The textures observed in rocks with more pronounced ductile foliation suggest middle degree conditions (450°C - 600°C and 6±1 kbar) during the Boa Sorte granite deformation. To the south it makes contact with Água Limpa granodiorite, it is intrusive into TTGs and Greenstone belts, and is intruded by plutons of mafic to intermediate composition of the Diopside Norite Pium, granites of the Planalto suite and mafic dykes. Four granite groups were distinguished on the basis of their different REE patterns: (1) this is the predominant group and it is characterized by high (La/Yb)N ratios, moderate negative Eu anomalies and concave pattern of heavy REE; (2) this group show low (La/Yb)N ratios and strong negative Eu anomalies; (3) the third group is depleted in light REE elements, with (Gd/Yb)N ratios close to unity, and shows moderate negative Eu anomalies; and (4) the fourth group is characterized by low REE contents, with high to moderate (La/Yb)N ratios. The geochemical characteristics of these groups are compatible with those of weakly peraluminous calc-alkaline I-type Archean granites. These rocks have high K2O, low contents of ferromagnesian elements, moderate CaO and Na2O and moderate to high Al2O3. K2O/Na2O ratios vary between 1 and 2. Despite the large compositional overlap between these groups, on average there is an increase in the SiO2 content from the high (La/Yb)N group (1) towards the low (La/Yb)N (2) and low (Gd/Yb)N ratios (3) groups. In Harker diagrams, the first and second groups tend to line up in well-defined trends, with the third showing on average higher Na2O and lower K2O, Zr and Hf. In addition to these differences, the fourth group has on average higher contents of CaO, Ba, and Sr and lower FeOt/(FeOt+MgO) and Rb. The Boa Sorte granite was formed more probably in the Mesoarchean, at 2857±2 Ma, and resulted from partial melting processes of crustal protoliths, whose oldest ages are around 3.00 Ga. Despite some geochemical affinity with the Potassic leucogranites represented by the Xinguara and Mata Surrão plutons, this granite differs from the Leucogranodiorite-granite group of the Rio Maria Domain. On the other hand, the groups with high and low (La/Yb)N ratio show good correspondence with the Cruzadão and in some respects Bom Jesus granites of the Canaã dos Carajás area. In its turn, the low (Gd/Yb)N ratio group resembles the Serra Dourada granite, while the group with low REE contents has more affinity with the Canaã dos Carajás granite. Such evidences suggest that the region comprising the Canaã dos Carajás area and the northeastern portion of the Água Azul do Norte municipality have been affected by similar processes during the Mesoarchean evolution of the Carajás Domain. That area was subsequently affected by the Neoarchean tectonic related to the closing of the Carajás Basin.
Acesso aberto (Open Access)
Geologia, geoquímica e mineralogia dos corpos anfibolíticos de Água Azul do Norte: condições metamórficas e implicações tectônicas para o Domínio Sapucaia - Província Carajás
(Universidade Federal do Pará, 2016-11-09) SOUZA, Diwhemerson Barbosa de; MONTEIRO, Lena Vírginia Soares; http://lattes.cnpq.br/6455990478032543; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The metamafics bodies identified in the Água Azul do Norte area, located in the south-central portion of the Carajás domain, crosscut the TTG basement and include two distinct varieties: (i) actinolite amphibolite, an extensive elongated body (~17 km long) with N-S orientation and inflection to NE, composed essentially of plagioclase and amphibole, with relicts of igneous pyroxene crystals and plagioclase, defining a subophitic texture; and (ii) diopside amphibolite, with occurrence restricted to the extreme east portion of the area, outcropping as small lenticular anastomosed bodies of NW-SE orientation. The latter shows nematoblastic and porphyroblastic textures, mylonitic foliation, and S-C pairs. The mineral paragenesis recognized in this variety include: Plg+Amph+Di+Ilm, which represent the metamorphic peak, while Plg+Amph+Ep+Clz+Tit+Ap+Qtz+Ser were generated during the retrometa-morphism. The plagioclase from the actinolite amphibolite has a broad compositional spectrum, ranging from calcic oligoclase to calcic labradorite (An28-65) with calcic compostions representing igneous inheritances. The plagioclase from the diopside amphibolite has more homogeneous composition and was classified as sodic andesine (An31-35). The amphibole from the actinolite amphibolite shows compositional zoning with Mg/Fe ratio slightly higher than those of the diopside amphibolite, and can be classified as Mg-hornblende, tschermakite, actinolite and edenite. In addition, the amphibole of the diopside amphibolite has AlVI of ~0.4 and Fe3+ of 0.7 to 0.8 contents, which allows its classification as Mg-hastingsite. Taking into account the chemical data, these bodies had a protolith with composition compatible with tholeiitic basalts, multielement standard of continental tholeiites (diopside amphibolite) and tholeiites low K (actinolite amphibolite), incompatible elements (HFSE) ratios suggest a source derived from primitive mantle, with significant changes in the magma composition due to interaction with the continental crust and/or subcontinental lithosphere. The chemical-mineralogical and textural evidences indicate that the protolith of actinolite amphibolite underwent deformation in the submagmatic stage and later a deformation in solid state at shallow depths. In contrast, the diopside amphibolite was submitted to ductile deformation regime in relatively higher depths. The metamorphic path of the actinolite amphibolite reveals isothermal decompression (metamorphic peak at 2.7 kbar and 430 °C; and retrometamorphic equilibrium at 1.2 kbar and 425 °C), associated with its exhumation and/or emplacement of leucogranite bodies, whereas the diopside amphibolite indicates amphibolite facies metamorphism in intermediate crustal level conditions (5 kbar; 540oC). These data indicate the exposure of relatively deep crustal levels in Água Azul do Norte (9-16 km).
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Geologia, geoquímica e petrologia magnética do magmatismo básico da área de Nova Canadá (PA), Província Carajás
(Universidade Federal do Pará, 2013-08-29) MARANGOANHA, Bhrenno; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
Through geologic mapping of the Nova Canadá area, was possible to individualize two mafic units, typified for diabase dikes, isotropic, and extensive bodies of amphibolites with nematoblastic and granoblastic textures, outcropping only in the southwestern part of the area. Both units cross-cut granitoids of Xingu Complex and Sapucaia greenstone belts sequence. They are classified as subalkaline tholeiitic basalts. Diabase dikes are divided into three varieties, namely hornblende-gabbronorite, gabbronorite and norite, being the differences between these ones only concerned the modal contents of amphibole, ortho- and clinopyroxene, once petrographically, they don’t show significant differences. They consist of plagioclase, ortho-/clinopyroxene, amphibole, Fe-Ti oxides and olivine; they show a moderate fractional pattern REE and unremarkable negative Eu anomaly. Tectonically, they are related to a continental intraplate environment, and show OIB and E-MORB-types signatures. On the other hand, the amphibolites show a flat REE pattern and an absence of Eu anomaly. They are classified as island arc tholeiites and show N-MORB-type signature. This lithotype includes plagioclase, amphibole, opaque minerals, titanite and biotite as main mineralogical phases. The mineral chemistry shows in the diabases no significant variation between plagioclase core and rim, being classified as labradorite, with rare andesine and bytownite; the amphibole shows a compositional gradation from Fe-hornblende to actinolite with increasing silica. In the amphibolites, the plagioclase shows a wide compositional variation, from oligoclase to bytownite in the foliated rocks; in the amphibolites less/no foliated, there is only sodic andesine. Pyroxene is only found in the diabase dikes and exhibits considerable variation compositional, showing a magnesium content increasing in the cores; the iron and calcium contents increase toward the rims; it is classified as augite, pigeonite (clinopyroxene) and enstatite (orthopyroxene). Diabase dikes have titanomagntite, magnetite and ilmenita as main Fe-Ti oxides. Textural analyses of these oxides allowed identifying five distinct forms of ilmenite in the diabase dikes: trellis ilmenite, sandwich ilmenite, patch ilmenite, individual ilmenite, internal and external composite ilmenite. Texture features suggest that titanomagnetite and individual and external composite ilmenite crystallized in early magmatic stage. During the subsolidus stage, titanomagnetite was transformed by oxidation-exsolution in intergrowths of almost pure magnetite and ilmenite (sandwich, patch, trellis and internal composite ilmenite). Amphibolites have ilmenite as the only Fe-Ti oxide mineral, that occurs as individual ilmenite, and it is always associated to amphibole and titanite. Norites and gabbronorites are characterized by the highest values of the magnetic susceptibility (MS); these varieties exhibit the highest modal opaque minerals content, having primary titanomagnetite as mineralogical phase. Hornblende-gabbronorites exhibit the moderate values of the MS, and amphibolites, the lowest ones. The negative correlation between MS values with modal ferromagnesian contents of the diabases shows that paramagnetic minerals (amphibole and pyroxene) don’t have significant influence in the magnetic behavior in these rocks. In contrast, the positive correlation between these variables, of the amphibolites, suggests these mineral phases are the main responsible for its values of the MS. Geothermobarometric data obtained from titanomagnetite-ilmenite pair in the diabase dikes show temperature and oxygen fugacity conditions (1112°C and -8,85, respectively) close to NNO buffer.
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Geologia, geoquímica e petrologia magnética dos granitoides Arqueanos da Porção Nordeste de Água Azul do Norte - Província Carajás
(Universidade Federal do Pará, 2012-09-10) GABRIEL, Eleilson Oliveira; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
Petrographic and geochemical studies of Archean granitoids under taken during the geological mapping of the NE portion of the Água Azul do Norte area - Carajás Province, allowed the identification of new units that were previously inserted into the Xingu Complex. The granitoids individualized are: (i) the Água Azul and Água Limpa granodiorites, which are high-Mg granitoids, similar geochemical to the Archaean sanukitoid occurring in other areas of the Carajás Province as well as in the Karelian and Superior provinces; (ii) a pluton of Trondhjemite with affinity to the classical TTG, not identified in previous studies in this area; (iii) three bodies of Leucogranodiorites and one of Leucogranite all of them with calc-alkaline signature and geochemically similar to the leucogranodiorites-granites of the Guarantã Suite of the Rio Maria Domain. These Archaean granitoid are intrusive in the supracrustal sequences of the Sapucaia Group and occur as deformed bodies, generally elongated along EW. The Água Azul and Água Limpa granodiorites are composed essentially of (epidote)- amphibole-biotite granodiorite and tonalite with (muscovite)-(epidote)-biotite granodiorite and monzogranites. Biotite trondhjemites and subordinate biotite tonalites are the rock varieties identified in the Trondhjemite pluton. The occurrences of Leucogranodiorites consist of biotite granodiorites, and the Leucogranite body is composed of biotite monzogranites. The Água Azul and Água Limpa granodiorites are predominantly metaluminous and exhibit higher values of Mg#, Cr and Ni when compared to the calc-alkaline series from continental margins and Archean TTG suites and leucogranodiorites of the Rio Maria Domain. The magnetic susceptibility (MS) values obtained in the rocks of these two bodies are relatively low (average 17.54 x10-4 SIv for the Água Limpa and average 4.19 x10-4 SIv for the Água Azul granodiorites). Magnetite and hematite are the more common opaque minerals and ilmenite is absent in these rocks. The magnetite crystals are more abundant and larger in the Água Limpa Granodiorite compared to the Água Azul Granodiorite, justifying the highest values of MS found in this pluton. In general there is a tendency of increasing of MS values in the sense of the less evolved facies (amphibole tonalite + amphibole granodiorite) to more evolved facies (biotite granodiorite + biotite monzogranite). The more magnetic samples are related to magnetite formed during deformational processes in shear zones. Because of the geochemical and mineralogical similarities between these rocks and sanukitoids of Rio Maria, it is assumed conditions of the fO2 between HM and FMQ buffers for granitoids of the Água Azul do Norte.
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Geologia, mineralogia e afinidades petrológicas dos granitóides neoarqueanos da porção central do Domínio Canaã dos Carajás
(Universidade Federal do Pará, 2017-10-28) OLIVEIRA, Vinícius Eduardo Silva de; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The central portion of the Canaã dos Carajás domain, located in the northern part of the Carajás province was originally marked by the occurrence of undifferentiated rocks belonging to the Xingu complex and Plaque suite, as well as greenstone belts, mafic rocks of the Pium diopside-norite and high K calc-alkaline leucogranites (Boa Sorte and Cruzadão granites). A semi-detailed geological mapping (1:100.0000) was carried out in the Vila União area and allowed the identification of several deformed granite bodies intrusive in the Mesoarchean units. They correspond to the most expressive unit of the studied area and are composed predominantly of monzogranites with chemical and mineralogical affinity with the Neoarchean A-type granites of the Planalto and Vila Jussara suites. The variable felsic and ferromagnesian minerals contents, as well as the different proportions between them, allowed to distinguish four major groups of granitoids: (i) biotite-hornblende monzogranites (BtHblMzG); (ii) biotite granites and leucogranites (BtLG); (iii) biotite-hornblende tonalites (BtHblTn); and quartz diorites (QD). The tectonic foliation of these rocks follows the regional E-W trend and exhibits high angles (70-85°). Well-developed core and mantle structures in quartz and feldspar crystals, as well as the presence of serrated and irregular contacts between these crystals suggest that dynamic recrystallization occurred at relatively high temperatures (> 500 °C). These rocks exhibit a wide variation in silica content (61.7 – 75.91 wt%), are metaluminous to slightly peraluminous and show affinity with A-type (high HFSE) and ferroan granites. Based on magnetic petrology studies it was possible to distinguish two groups of rocks: (1) granites containing only ilmenite with low magnetic susceptibility values (MS; <0.570 × 10-3 SI), and (2) granites with magnetite as the main iron and titanium oxide mineral and higher MS values (> 1.437 × 10-3 SI). Textural and compositional evidences indicate that magnetite and ilmenite are earlycrystallized phases and titanite has magmatic origin. Amphiboles are calcic and classified as hastingsite, whereas biotites are rich in the annite molecule. The relatively high Fe/(Fe + Mg) ratios found in the amphiboles of the BtHblMzG and BtHblTn varieties indicate that these granitoids were formed under low to moderate fO2 conditions, whereas in the BtLG the lower values of this ratio suggest more oxidizing conditions. Geothermometers point to crystallization temperatures between 830 – 930 °C in the different facies. The high total Al content in the amphibole crystals suggests crystallization at pressures between 400 and 800 MPa, indicating that these granitoids were emplaced at different crustal depths.
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Geologia, petrografia e geoquímica das associações leucograníticas e TTG arqueanos da área de Nova Canadá (PA) Domínio Carajás
(Universidade Federal do Pará, 2014-02-25) SANTOS, Pablo José Leite dos; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The geological mapping carried out in the Nova Canada and Velha Canada villages, south portion of the Carajas Domain, ally to the petrographic and geochemical data allowed to the characterization of new geological units before inserted in the Xingu Complex geological context. In abundance order they are: (i) Nova Canada Leucogranodiorite composed predominantly by leucogranodiorite rocks that are more enriched in Al2O3, CaO, Na2O, Ba, Sr and in the Sr/Y ratio. They show strong geochemical affinities with Guarantã Suites from the Rio Maria Domain, which are also correlated to Transitional TTGs from Yilgarn Craton. Their REE pattern is slightly fractionated with low (La/Yb)N ratios with Eu negative anomalies absent or discrete; (ii) Velha Canadá Leucogranite comprised essentially by leucogranitic rocks that show higher contents of SiO2, Fe2O3, TiO2, K2O, Rb, HFSE (Zr, Y e Nb), and K2O/Na2O, FeOt/(FeOt+MgO), Ba/Sr e Rb/Sr ratios. The Velha Canada area rocks are characterized by two distinct patterns REE of: (a) moderate to low (La/Yb)N ratios with accentuated Eu negative anomalies, and (b) high to moderate (La/Yb)N ratios with discrete Eu negative anomalies. A concave HREE pattern is observed. In several aspects, the Velha Canada granite show similarities with K-Leucogranites like Xinguara and Mata Surrão granites from Rio Maria Domain, and more discretely with low-Ca granites from Yilgarn Craton. To origin of Nova Canadá Leucogranodiorite rocks is admitted fractional crystallization by sanukitoid liquids, following by mixing with trondhjemitic magmas, while for those high-K rocks is assumed partial melting of metatonalites rocks related to TTG Suites on different crustal levels, for give rise to these liquids; and (iii) Trondhjemitic associations with high-Al and low-K calc-alkaline TTG series affinities. Two varieties were distinguished: (a) biotite-trondhjemite with deformational features like compositional banding, folds and evidence of migmatization, suggesting the presence at least two compressional events during the sin- and post magmamtic stages; and (b) (muscovite) biotite-trondhjemite that differs from the previous one by the presence of muscovite, plagioclase saussuritization, medium evengrained texture and discrete deformation features with development of a low-angle foliation with E-W direction. The restrict occurrence of the first one, ally with intense deformation and eventual anatexie processes that affected these rocks, can indicate a crustal rework linked to generation of the leucogranites described in the Nova Canadá area. The trondhjemites of the southern part of area are more enriched in Fe2O3, MgO, TiO2, CaO, Zr, Rb, an in the Rb/Sr ratio in relation to those of the northern part. The arrangement of trends defined by the set of analyzed samples, suggests that theses varieties are not cogenitc or comagmatic. These rocks also show fractionated REE patterns, with variations in contents of the heavy REE and Strong light REE enrichment, besides the absence of the Eu and Sr anomalies, and low contents of Yb and Y. Such aspects are tipically attributed to magmas generated from partial melting of a mafic source at different depths, with increasing of the garnet influence in the residue, as well as the lack of plagioclase in both residual and fractionating phases. Geochemical affinities between the rocks studied with those of the mesoarchean Rio Maria domain, suggest the extension of Rio Maria Domain to north until the Nova Canadá area, while that the leuocogranodiorites of the Velha Canadá area, that are younger and generated in the neoarchean, discard the hypothesis to associate the generation of these rocks to the same tectonic-magmatic events that acted in Rio Maria.
Acesso aberto (Open Access)
Geologia, petrografia e geoquímica das associações TTGs e Leucogranodioritos do extremo norte do Domínio Rio Maria, Província Carajás
(Universidade Federal do Pará, 2013-06-18) SILVA, Chrystophe Ronaib Peixoto da; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The geological mapping carried out in the southeastern portion of Água Azul do Norte / PA, northern part of the Rio Maria domain, ally to the petrographic and geochemical data allowed the individualization of TTGs associations and leucogranodiorites. In this region, mapping was performed only on regional scale which allowed the extrapolation of the area of occurrence of rocks similar to Caracol Tonalite and Mogno Trondhjemite. The TTGs studied were individual in two units based on the contents of mafic minerals, concentration of magmatic epidote and degree of saussuritization of the plagioclase in: (1) Epidote-Biotite Tonalite and, (2) Biotite-Trondhjemite. In general, rocks which have a foliation defined by compositional banding which locally can be disturbed by folds and shear bands. Their geochemical characteristics are consistent with Archean TTG group of high Al2O3 and are still relatively poor in ferromagnesian elements, with HREE pattern moderaly to strongly fractionated and Eu discrete anomalies. The differences in the ratios La/Yb and Eu anomalies, allowed todiscrimination three distinct groups of rocks: The TTGs belonging to the group of high La/Yb, Sr/Y are similar to rocks Mogno Trondhjemite described in Rio Maria Domain. These rocks include the most samples of the unit Biotite Trondhjemite. In the case of TTGs with medium to low La/Yb, Sr/Y compared with the rocks of the Rio Maria area are strongly correlated with the Tonalite Caracol. These groups are composed mainly by unit Epidote- Biotite Tonalite, including also isolated samples the Biotite Trondhjemite. On the basis of geological, petrographic and geochemical data leucogranodiorites of the study area were divided into two groups: Biotite Granodiorite and Leucogranodiorite. The rocks of the Biotite Granodiorite have wide spatial occurrence in the western portion of the area. Field relationships show that these rocks are intrusive in granitoids TTGs. The available geochemical indicate that the Biotite Granodiorite have as well fractionated REE patterns, with high ratio La/Yb (33-186) and Eu anomalies quite pronounced, being strongly positive (1,11 < Eu/Eu* < 3,26). Whereas leucogranodioritos show slightly fractionated patterns, with moderate ratios La/Yb (24.7 to 34.7) and Eu anomalie absent (Eu / Eu * = 1.03). The Harker diagrams for major and trace elements do not favor a genetic link by fractional crystallization processes between the Biotite Granodiorite and TTG associations, considering present distinct evolution trends, thus indicating that the conditions of their genesis and differentiation were quite different, either by partial melting of a TTG source by the fact of the leucogranites not to present significant negative Eu anomaly, as well as for to show similar patterns of REE fractionation in relation to TTG suites, attesting that these rocks were probably not derived from precursor magmas of the TTG suites.
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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.
Acesso aberto (Open Access)
Granitoides colisionais mesoarqueanos de Ourilândia do Norte (PA): geologia, microestrutural, afinidades petrológicas e implicações tectônicas para a Província Carajás
(Universidade Federal do Pará, 2017-06-17) SILVA, Luciano Ribeiro da; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
This study investigates the diversity, origin and tectonic significance of the Mesoarchean granitoids of Ourilândia do Norte, emplaced near Rio Maria-Canãa dos Carajás domains boundary, southeastern Amazonian Craton (Brazil). Previous work, done in this region, has identified granitoids of sanukitoid affinity (~ 2.87 Ga), (quartz) diorites of BADR (basalt, andesite, dacite, rhyolite) affinity and undifferentiated leucogranites. In addition there are monzogranites with clinopyroxene, cross-cutting the Mesoarchean granitoids. In this study, new geological mapping data allowed to define the nature and structural aspects of the leucogranites undifferentiated. These data allowed to differentiate three new groups of granitoids, classified as: (i) biotite monzogranites (BMzG); (ii) epitote-biotite granodiorites (EBGd); and (iii) porphyritic granitoids (pGrt). In this respect, this dissertation aims to define the classification, nature, formation processes and deformation aspects of these rocks, and discuss, from the integration of these data with those generated in previous works, the relations between plutonism and deformation for the formation of the Ourilandia do Norte granitoids. For this was used an integrated approach of field, petrography, microstructural and geochemistry data. The petrography data show that the first two groups (BMzG and EBGd) are both subdivided into two facies. The BMzG is differentiated into equigranular (eBMzG) and heterogranular (hBMzG) facies and the EBGd into heterogranular epitope-biotite granodiorite (hEBGd) and sparsely porphyritic titanite-epitoto-biotite granodiorites (spTEBGd). These granitoids constitute two batholiths separated by a rock strip of sanukitoid and BADR affinity. The main batholith has an ellipsoidal shape, with the largest axis oriented in the ENE-WSW direction, and other is arc-shape. Both are largely dominated by BMzG rocks, with less occurrence of EBGd lenses. The pGrt is individualized in porphyritic biotitehornblende granodiorite (pBHGd) and porphyritic epidote-biotite trondhjemite (pEBTd), and occurs as smaller bodies, spatially associated with rocks of sanukitoid and BADR affinities, respectively. The mingling relationships established the contemporaneity between all the Ourilândia do Norte granitoids, including those of sanukitoid and BADR signatures. In terms of structural geology, these plutons were affected by heterogeneous deformation. Their central portions represent lower strain domains, where ocours magmatic foliation of ENE-WSW main direction and subvertical dip, with weak superimposition of solid-state deformation. On the other hand, the borders of these plutons are marked by large-scale shear zones, where milonitic foliations are typically developed, with suballel trend to the batholith border and subvertical dip. The meso- and microstructural data indicate that the rocks studied are syn- to late-tectonic and were affected by high temperature deformation (> 500 ºC) and low differential stress, in a sinistral transpression regime, predominantly controlled by pure shear, indicating that the magmatic and solid-state fabrics are related to the a same deformational event. Geochemically, except the EBTdp facies that has Mg-Na affinity, the Ourilândia do Norte granitoids can be grouped into two suites: (i) Fe-K suite that integrates the BMzG group and the spTEBGd facies; and (ii) Mg-K suite composed of granitoids (including EBGdh and BHGdp) and (quartz) diorites of sanukitoid and BADR affinities, respectively. Both groups are alkali-calcic to calc-alkaline and they differ on the basis of their FeOt /MgO ratios, Al2O3, K2O and some trace elements (Sr, Ba, Rb). The origin of the eBMzG is attributed anatexis a 2.92-2.98 Ga old TTG crust. The hEBGd has sanukitoid affinity and could have been produced by intense fractionation of hornblende ± clinopyroxene. The granitoids of spTEBGd, hBMzG, pBHGd and pEBTd facies show evidence of mingling between contrasting magmas, indicating that their origins require interaction between metassomatized mantle- and crustal derived magmas. Geochemical data and modeling were used to identify the different processes related to the origin and formation of these granitoids: (i) spTEBGd is enriched in HFSE (Ti, Zr and Y ) and LILE (Ba and Sr) and was admitted as product of the partial melting of an enriched mantle source, with participation of crustal liquids, probably in a post-subduction setting; (ii) hBMzG is generated by the interaction between magmas of spTEBGd (60%) and eBMzG (40%) composition; (iii) pBHGd is formed by the hybridization between sanukitoid (80%) and leucomonzogranitic (20 %) magmas; and (iv) pEBTd is formed by an incomplete mixture between TTG signature trondhjemitic liquid (70-80%) and magma of BARD affinity (20-30%). Therefore, we can conclude that in ~2.87 Ga a significant crustal growth and reworking occurred in the final stages of stabilization of the first geotectonic cycle of Carajás province. This leads us to suggest that all the Ourilândia do Norte Mesoarchean granitoids were emplacement during the second stage of a tectonomagmatic two-stage (subduction-collision) model: (i) first stage (2.98-2.92 Ga) - low-angle subduction with emplacement of slab-melt and consequent mantle wedge metasomatism; (Ii) second stage (~ 2.87 Ga) - emplacement of the granitoids studied in a collisional environment, where shear zones conditioned the rise and emplacement of magmas, acting as deep-reaching discontinuities and important conduit for transport and interaction between mantle- and crustal-derived magmas.
Acesso aberto (Open Access)
Granitóides TTG de Água Azul do Norte: implicações tectônicas para a Província Carajás
(Universidade Federal do Pará, 2016-12-15) SANTOS, Marcela da Silva; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The rocks that compose the TTG crust from the Água Azul do Norte area are dominantly trondhjemites and are strongly akin to others TTG occurrences in Carajás domain (Rio Verde and Colorado trondhjemites and related rocks from Nova Canadá area), differing from those of the Rio Maria domain (Caracol, Arco Verde, Mariazinha tonalities and Mogno, Água Fria trondhemites) due the presence of more evolved terms, lower primary accessory minerals contents and for being essentially peraluminous, without strongly decalcified plagioclase. They exhibit moderate to high La/Yb and Sr/Y ratios, and low Nb/Ta ratio, which indicate that they were produced from partial melt of metamafic source, at high to intermediate pressure conditions (~1.0-1.5 GPa). The large tonalitic enclaves indentified have particular mineralogical and geochemical features that do not allow associating them with the typical TTG associations. They exhibit significant amphibole contents (>5%), high Fe2O3, MgO, CaO, Ni e Cr contents, and a flat RRE pattern (low La/Yb ratio), which reflect their less evolved character compared with TTG granitoids. The low La/Yb and Sr/Y ratios indicate that they were produced out the garnet stability field, in lower pressure conditions than TTG granitoids (≤ 1.0 GPa), and they could represent magmas with transitional behavior between typical TTG and sanukitoids. The less evolved character of the enclaves compared with the São Carlos tonalite, which represent the oldest fragment of Mesoarchean crust from Carajás domain, associated with their chaotic structural patterns, suggest that these enclaves can represent preserved parts of an even older crust. Structural data suggest that the TTG crust records at least two important deformational moments played in the area with coincident principal shortening axis (N10-20°E). The first moment (D1 ~2,93 Ga) is evidenced for the compositional banding (E-W) formed by a strong pure shear component during the TTG granitoids emplacement. The late phase of ductile deformation (D2 ~2,87 Ga), under medium amphibolite metamorphism facies conditions (550°C), is marked by the transposition of simple and pure shear of the ancient structures, which originated the NW-SE, N-S, NE-SW and E-W foliation patterns. This deformational moment is strongly linked to late intrusions of sin to post-tectonic Mesoarchean leucogranites. The transpressive strain identified in the area suggests that the plates convergence was active between 2.93 and 2.87 Ga, and during the last phase of transpression, the strain was partitioned with the total stress of simple shear being accommodated in shear zones and shear bandings. As consequence, there is the preservation of regions with low deformation among shear zones controlled by pure shear. The existence of a TTG crust in Água Azul do Norte region compositionally distinct from Rio Maria domain, in addition to a complex deformational pattern that is usually associated with migmatization processes, suggest that this portion of Carajás domain does not represent an extension of the Rio Maria domain, but an independent Mesoarchean crust fragment without records of Neoarchean events, which would not be in compliance to the definition attributed to Sapucaia subdomain.
Acesso aberto (Open Access)
Granodiorito Rio Maria e rochas associadas de Ourilândia do Norte – Província Carajás: geologia e afinidades petrológicas
(Universidade Federal do Pará, 2015-07-22) SANTOS, Maria Nattania Sampaio dos; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
The granitoids of sanukitoid affinity of the Ourilândia do Norte area, located near the Rio Maria-Carajás domain boundary, are associated with Rio Maria sanukitoid suite from the Mesoarchean age. In this area dioritic, quartz-monzodioritic, tonalitic and granodioritic rocks with variable proportions of amphibole and biotite were described. Contrary to what is observed in the sanukitoid rocks of the Rio Maria area, those of Ourilândia do Norte are constantly affected by deformational processes, relating to the installation of the Itacaiúnas Shear Zones. They exhibit pervasive foliation and microstructures developed under three dynamic recrystallization regimes: (1) Bulging recrystallization (300-400°C); (2) Subgrain rotation recrystallization (<500°C); (3) Grain boundary migration recrystallization (<600°C). Granitoids with sanukitoid affinities are magnesian and metaluminous and belong to medium to high potassium calc-alkaline series. They display non-collinear trends from (quartz) diorite toward granodiorite and exhibit a negative correlation for compatible elements (CaO, Fe2O3 t, MgO, TiO2, Zr, Ni, Cr and #Mg) and inverse behavior for incompatible ones (Ba, Sr), as well as Rb/Sr and Sr/Ba ratios. Moreover, they show amphibole, clinopyroxene and subordinate biotite and plagioclase fractionation. The clinopyroxene-bearing monzogranite shows trends parallel to those of sanukitoids and has a lower Sr/Ba ratio and #Mg content, due to its ferrous character, and probably does not belong to the sanukitoid series. The REE pattern of granodiorite shows a slight or absent Eu anomaly (Eu/Eu*=0.76-0.97) and moderate (La/Yb)N ratio, indicating garnet, amphibole or pyroxene fractionation. Tonalites are less depleted in HREE and have little Eu anomaly (Eu/Eu*=~0.95). Enclaves, (quartz) diorite and quartzmonzodiorite exhibit negative to positive Eu anomalies (Eu/Eu*=0.56-1.71) and a low (La/Yb)N ratio, whose horizontal pattern is similar to that of intermediate rocks from the Rio Maria area. Clinopyroxene-bearing monzogranite shows affinities for the tholeiitic series, following slightly different trends from granitoids, with a negative Eu anomaly (Eu/Eu*= 0.63-0.98) and (La/Yb)N slightly fractionated ratios. Negative Nb-Ta-Ti anomalies, associated with high (La/Yb)N and Y/Nb ratios suggest that these rocks were generated in a subduction zone from a depleted source mantle which was contaminated by fluids or melt. Analysis of the metassomatic agent nature revealed that less evolved rocks were contaminated by fluids, while granodiorites and related rocks were contaminated by melt, whose composition is similar to that of tonalite-trondhjemite-granodiorite (TTG). Enclaves, (quartz) diorite and clinopyroxene-bearing monzogranite were produced by relatively low pressures (La/Yb<1.0 GPa) and depths (<33.6 Km), with little or no residual garnet, while the other granitoids could ix have been generated under superior geothermal conditions (La/Yb=1.0-1.5 GPa; 33.6-50.5 Km) with variable proportions of residual garnet. Furthermore, these granitoids started to crystallize at depths between 30.3 and 20.2 Km and ended between 10.1 and 6.7 Km. Ourilândia do Norte sanukitoid rocks and the other analoguous intrusions of the Carajás Province show geochemical and petrogenetic affinities with high-SiO2 adakites and low-TiO2 sanukitoids. They may have originated through a one-stage process, by direct hybridization between the mantle and TTG-melt. Nevertheless, the modeling performed on Rio Maria and Karelian sanukitoids indicates that they were produced by a two-stage process, from meltmetasomatized peridotite remelting.
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Magmatismo bimodal da área de Tucumã, Província Carajás: geocronologia U-Pb, classificação e processos
(Universidade Federal do Pará, 2015-08-06) SILVA, Fernando Fernandes da; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506
In the geological context of the Carajás Province, dikes are an important mechanism for magma transport and represent the beginning of a rifting, which allow the emplacement through the crust significant amounts of magma. The geological mapping of the Tucumã area has enabled the identification of dike swarms, which are intruded in an Archean basement. The disposition of these dikes is consistent with the regional, NW-SE trending, and can reach up to 20 kilometric lengths. They were individualized in three main groups: (i) felsic dikes (70% of the dikes), composed exclusively of pink to dark purple porphyritic rhyolites with euhedral phenocrysts of quartz, K-feldspar and plagioclase immersed in a felsitic afiric matrix; (ii) mafic dikes, with restrict occurrence, composed primarily of basaltic andesites and subordinately by basalts, with a mineralogical assembly represented by plagioclase, cline- and orthopyroxene and olivine, forming an ofitic texture; and (iii) intermediate rocks, represented by gray to greenish gray andesites and dacites. Dacitic rocks are found outcropping associated to felsic dikes, showing different degrees of hybridization or mixing between mafic and felsic magmas. This is evidenced by large presence of mafic enclaves in the felsic dikes and the frequent presence of embayment textures. SHRIMP U-Pb zircon dating of felsic dikes yielded an age of 1888 ± 3.3Ma, which is interpreted as crystallization age. The felsic dikes are peraluminous to slightly metaluminous mainly due to the fractionation of K-feldspar and plagioclase with minor contribution of amphibole. They are characterized as akin to A2, ferrous and reduced granites. The intermediate and mafic dikes belong to tholeiitic series and are exclusively metaluminous with large fractionation of amphibole and plagioclase. It is noted a decrease in the amounts of CaO, FeOt, MgO, TiO2, Sr, Cr and P in the mafic rocks in the direction to the rhyolitic composition, which are more enriched in silica, while K2O/Na2O, Al2O3 and Na2O, Rb, Ba and Y increase in the same sense. In rhyolitic varieties, the REE patterns are characterized by LREE enrichment in relation to HREE (high ratios La/Yb), and a significant Eu anomaly. A similar behavior is also seen in the intermediate rocks. On the other hand, the mafic rocks presents flatter REE patterns (low ratio La/Yb) and little or no Eu anomaly. Geochemical modeling and the fractional crystallization vectors showed that the mafic rocks evolved by crystallization of pyroxene and plagioclase, while the K-feldspar and biotite are the fractionating phases in felsic magma. For a discussion about the origin of the intermediate rocks, it was utilized a simple binary mixture model, in which the rhyolites and basaltic andesite are the primary components. From this model was shown that by mixing of 60% of rhyolite and 40% of basaltic andesite melts is possible to generate the dacite composition, while the andesite liquid could be x originated by mixing of 60% and 40% of basaltic andesite and rhyolite melts, respectively. The model proposed suggested that mixing of basaltic and andesitic magmas occurred during the ascent and storage in the crust, where the andesitic dikes are probably generated by a more homogeneous mixture at high depths in the continental crust (mixing), while the dacite dikes can be generated in the upper crust at a lower temperature, thus providing a less efficient mixing process (migling). The petrographic, geochemical, and geochronological affinities observed between the felsic dikes studied and the A-type granites of the Rio Maria and São Felix do Xingu regions, demonstrate that the bimodal magmatism of the Tucumã area is a clear evidence that the Paleoproterozoic magmatism of the Carajás Province has been formed by processes involving thermal perturbations in the upper mantle, mafic underplating, and associated extension or transtension of the crust.
Acesso aberto (Open Access)
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.