DEGEO - Departamento de Geologia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8
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Item Andean fingerprint on placer sands from the southern Brazilian coast.(2022) Rizzi, Monique Aparecida Marchese; Dillenburg, Sérgio Rebello; Takehara, Lucy; Girelli, Tiago Jonatan; Wust, Cássia Fatima; Lana, Cristiano de Carvalho; Chemale Júnior, FaridOn the passive margin of southern Brazil, where the availability of sediments and coastal system conditions were adequate for forming a Ti–Zr-bearing placer in the Holocene, could there be a source of detrital contribution other than the Precambrian South American cratons? To answer that, detrital zircon U–Pb–Hf analyses were performed using the LA-ICP-MS method. The U–Pb age pattern distribution of 866 zircon grains showed that 35.3% of the grains belong to the Neoproterozoic, which covers the Brasiliano orogenic belts. However, 9.1% of the total zircons analyzed (up to 12% in some samples) correspond to grains younger than 50 Ma, restricted to the Andean orogeny in southern South America. The Hf signature of the zircons stands out by pointing to five significant and distinct groups interpreted as coming from the Andean (0–50 Ma), Gondwanides (230–380 Ma), Famatinian (380–500 Ma), Brasiliano (850–541 Ma), and Grenville (900–1300 Ma) orogens, confirming an Andean fingerprint as source rocks in addition to the sediments originating from the craton. This Andean source is related to the distal sediment contribution from the La Plata River system and Argentina rivers that discharge in the Atlantic Coast. Based on a statistical and Hf isotope approach, we defined that around 50% of the zircons grains were transported from the Argentina coast and La Plata River by the littoral drift for more than 1000 km to their final sink in the southern Brazilian coast.Item Unraveling multiple tectonic events and source areas in the intracratonic Bauru Basin through combined zircon geo and thermochronological studies.(2020) Dias, Airton Natanael Coelho; Chemale Júnior, Farid; Candeiro, Carlos Roberto dos Anjos; Lana, Cristiano de Carvalho; Guadagnin, Felipe; Sales, A. S. W.The application of Fission-Track Thermochronology (FTT), and U-Pb and Lu-Hf isotope analyses on the same zircon grains revealed the provenance and thermal/tectonic events related to the build-up and evolution of the Bauru Basin filling in Minas Gerais, Brazil. The U-Pb on detrital zircon reveals that the potential source areas were dominated by Brasiliano outcrops and subordinately, Paleoproterozoic, Mesoproterozoic, and Carboniferous sources. Positive εHf(t) signatures can characterize the Goias ´ magmatic Arc and older adjacent terranes as the most probable region that supplied the Bauru Basin. The FTT data display five main age peaks at 569, 337, 235, 132, and 83 Ma. They record the exhumation and denudation processes of Brasiliano and Gondwanide orogens and later, the Serra Geral magmatism of the South American Platform. A younger subordinate age (100–80 Ma) is recorded, and it may be associated with intense alkaline magmatism that occurred during the initial stages of basin deposition.Item The Ribeirão da Folha ophiolite-bearing accretionary wedge (Araçuaí orogen, SE Brazil) : new data for Cryogenian plagiogranite and metasedimentary rocks.(2020) Amaral, Leandro Silva dos Santos; Caxito, Fabrício de Andrade; Soares, Antônio Carlos Pedrosa; Queiroga, Gláucia Nascimento; Babinski, Marly; Trindade, Ricardo Ivan Ferreira da; Lana, Cristiano de Carvalho; Chemale Júnior, FaridThe Araçuaí orogen and West Congo belt make up a singular confined orogenic system, embraced by the San Francisco – Congo craton: the AWCO. It includes a southern sector with ophiolite bodies and magmatic arc, and a northern sector free of them, suggesting the precursor basin was an embayment partially floored by oceanic crust. The northernmost ophiolitic rock-assemblage found in the Araçuaí orogen comprises metamafic and meta-ultramafic rocks with signatures of ocean-floor magmas, and associated pelagic to oceanic metasedimentary rocks of the Ribeirão da Folha Formation. Although tectonically dismembered and metamorphosed, those rocks resemble the classical ophiolite pseudostratigraphy. The Ribeirão da Folha Formation comprises rocks expected to be found in the upper units of an ophiolite edifice, like Al-rich micaschist (pelagic pelite), graphite-rich schist (black shale), sulfide-bearing metachert, diopsidite with massive sulfide, and banded iron formations (chemical-exhalative sediments), and sulfide-bearing fine-grained ortho-amphibolite with thin metachert intercalations (mafic volcanic unit). That formation hosts tectonic slices of banded ortho-amphibolite (dolerite) with plagiogranite veins, and coarse-grained massive ortho-amphibolite (gabbro), representing dismembered slivers from deeper mafic units, and slices of meta-ultramafic rocks from the deepest ophiolite units. Zircon crystals from a plagiogranite vein yielded the U-Pb SHRIMP age of 645 ± 10 Ma, providing a new time constraint for ocean-floor emplacement. Micaschist samples show chemical attributes typical of distal passive margin pelites. Among three progressive deformation phases, the main ductile phase (Dn) shows kinematic indicators related to top to SW mass transport, associated with intermediate P-T (St, Ky, Sil) metamorphic zoning. Although the few youngest grains of detrital zircon from three siliciclastic samples have distinct ages (around 599 Ma, 741 Ma, and 816 Ma), their wide-range age spectra and Hf signatures suggest similar sediment sources. The wide lithological variety and stratigraphic complexity along with the intricate tectonic framework of the Ribeirão da Folha region, comprising thrust slices of ophiolitic rocks tectonically interleaved with older rift-related rocks, characterize an accretionary wedge that was scrapped off the subducted slab and involved in collisional tectonics, marking the AWCO suture zone for some 250 km between the Guanhães basement block (lower plate) and Rio Doce magmatic arc (upper plate).Item Provenance and paleogeography of the Southern Paraná Basin : geochemistry and U\\Pb zircon geochronology of the Carboniferous-Permian transition.(2019) Tedesco, Julia; Cagliari, Joice; Chemale Júnior, Farid; Girelli, Tiago Jonatan; Lana, Cristiano de CarvalhoThe Carboniferous-Permian transition of the intracratonic Paraná Basin (S Brazil) includes important evidence of the climate change, tectonics, and paleogeographic configuration of SW Gondwana. During this period, the Late Paleozoic Ice Age (LPIA) was in its final phase in the Paraná Basin, producing a temperate-tropical climate through the transition to the Permian. UPb laser ablation ICP-MS detrital zircon dates and whole-rock geochemistry of rocks from the upper Itararé Group (Carboniferous) and the lowermost Rio Bonito Formation (Early Permian) in the southern Paraná Basin are determined to characterize the sedimentary-dispersal patterns of the source area and glacial paleoflow. Geochemistry proxies suggest that the studied units experienced different degrees of weathering, with the Itararé Group's units forming in an arid environment. The overlying Rio Bonito Formation's units were deposited under hotter and more humid climate conditions. The Late Carboniferous to Early Permian units showed similar zircon-age distribution patterns, with a Neoproterozoic main peak from the Uruguayan Sul-Riograndese Shield. A lack of Mesoproterozoic sources in the studied samples indicates that this area of the Paraná Basin probably did not receive sediments from the African side during the Late Carboniferous as previously described. This result suggests a more complex system in which ice caps and small ice sheets dominated the glacial environment during the Late Carboniferous in this segment of SW Gondwana.Item Granulite accretion to Rio de la Plata Craton, based on zircon U-Pb-Hf isotopes : tectonic implications for Columbia Supercontinent reconstruction.(2018) Girelli, Tiago Jonatan; Chemale Júnior, Farid; Lavina, Ernesto Luiz Correa; Laux, Jorge Henrique; Bongiolo, Everton Marques; Lana, Cristiano de CarvalhoThe paleogeographic reconstruction of the Rio de la Plata involved either allocthonous or autochthonous process reflecting directly the Paleoproterozoic connection of the craton to Columbia Supercontinent. Santa Maria Chico Granulite Complex is a significant fragment of Rio de la Plata intensely affected by the Brasiliano Orogeny. Zircon U-Pb-Hf isotopes by LA-ICP-MS, mineral and whole-rock chemistry and a pseudo-section are presently interpreted. U-Pb-Hf isotopes characterize two main accretionary and metamorphic events: oceanic juvenile crustal accretion (i) 2430–2290 Ma (εHf(t) = −3.17 to +7.00), with arc related metamorphism (830–870 °C, 6.7–7.2 kbar) at ~2.3 Ga; and continental arc accretion (ii) 2240–2120 Ma (εHf(t) = −4 to +2.4), with continental collision metamorphism (770–790 °C, 8.7–9.1 kbar) at 2.1–2.0 Ga. Alkaline granitic dikes related to crustal extension at 1.8 Ga cut the granulitic rocks after the stabilization of this crustal segment. The present data point to formation of Paleoproterozoic granulitic rocks of the Santa Maria Chico Granulite Complex and adjacent Nico Pérez and Rivera terranes in multi-stage volcanic arcs to continental collision environment over 370 Ma (2430 to 2060 Ma). These terranes were amalgamated in the Paleoproterozoic to the core of the Rio de la Plata Craton as part of Columbia Supercontinent and intensely reworked during the amalgamation of Western Gondwana in the Neoproterozoic.Item Geochemistry and isotopic signatures of metavolcanic and metaplutonic rocks of the Faina and Serra de Santa Rita greenstone belts, Central Brazil : evidences for a Mesoarchean intraoceanic arc.(2017) Borges, Caio César Aguiar; Toledo, Catarina Labouré Bemfica; Silva, Adarlêne Moreira; Chemale Júnior, Farid; Jost, Hardy; Lana, Cristiano de CarvalhoThe Archean-Paleoproterozoic Terrane of Goiás, Central Brazil, is an allochthonous block within the Neoproterozoic Tocatins Province and consists of an association of Archean TTG complexes and goldbearing Archean-Paleoproterozoic greenstone belts. The Faina and Serra Santa Rita greenstone belts, located in the southern portion of the terrane, are investigated using geochemistry and isotope geology to establish the time of magmatism and tectonic environment. Our data show that the ultramafic rocks have some chemical characteristics similar to modern boninites, whereas the amphibolites are subdivided into two groups: the type 1 basalts group are tholeiites with flat REE patterns and are similar to back-arc basin basalts; the type 2 basalts group have high Nb contents and are comparable to Nbenriched basalts. Felsic to intermediate rocks present some of the main chemical diagnostic features of adakites, in which the metandesites and metatonalites are comparable to high-SiO2 adakites, and the metadiorites, characterized by very high MgO, Cr and Ni contents, are comparable to low-SiO2 adakites or high-Mg andesites. Metavolcanic and metaplutonic rocks show two main periods of magmatic crystallization ages with juvenile and slightly crustal contaminated rocks. The first occurred at 2.96–2.92 Ga with positive ƐNd (t) values of +2.16 to +2.77, while the second formed at 2.8 Ga with slightly negative ƐNd (t) value of 0.15. The volcanic and plutonic protoliths of the two greenstone belts were formed in an intraoceanic forearc-arc-back-arc system. The initial stage corresponds to ultramafic lava eruption in the forearc region of a proto-island arc, at 2.96 Ga. The evolution of the island arc and subduction progression led to oceanic slab-melting and generation of adakites. At 2.92 Ga, the adakitic melt was totally consumed by peridotite mantle and the subsequent melting of these hybridized mantle wedge generated high-Mg andesites that lodged in the crust as dioritic intrusions with high MgO, Cr and Ni contents. The late-stage corresponds to a continental arc formation at 2.8 Ga, marked by tonalitic magmatism and amalgamation with other island arcs and continental arcs of the TTG complexes of the Archean- Paleoproterozoic Terrane of Goiás.Item The tectonic evolution of the Quadrilfitero Ferrifero, Minas Gerais, Brazil.(1994) Chemale Júnior, Farid; Rosière, Carlos Alberto; Endo, IssamuThe structural framework of the Quadrilatero Ferrifero is the result of two main deformational events. The first is an extensional event of Palaeoproterozoic age (between 2100 and 1700 Ma, the Transamazonian Event), which resulted in the formation of Archaean granite-gneiss domes and the nucleation of regional synclines in the overlying Rio das Velbas and Minas supergroups strata. Such regional synclines are continuous with each other and are bordered by structural granite-gneiss highs. At the contact between these units, ductile-brittle to ductile extensional shear zones are developed, representing the dislocation surfaces of Archaean blocks. This tectonism is probably related to the evolution of a metamorphic core complex, formed in the hinterland to the west of a Transamazonian collision zone, which structured the Paramirim Craton. The second event is compressive and associated with the closure of the Pan-African/Brasiliano protoocean (650-500 Ma), situated to the east of Quadrilltero Ferrffero (QF). During this event, a west-verging foldandthrust belt (FTB) developed, causing inversion, amplification, translation and rotation of the basinal synclines. The FTB affected mainly the eastern portion of QF and obliterated many of the tectonic features of the extensional event.Item Provenance and paleogeographic reconstruction of a mesoproterozoic intracratonic sag basin (Upper Espinhaço Basin, Brazil).(2014) Santos, Marcelo Nascimento dos; Chemale Júnior, Farid; Dussin, Ivo Antonio; Martins, Maximiliano de Souza; Queiroga, Gláucia Nascimento; Pinto, R. T. R.; Santos, A. N.; Armstrong, RichardThe Mesoproterozoic Conselheiro Mata Group is the uppermost sequence of the Proterozoic intracontinental Espinhaço basin that developed on the Congo-São Francisco Paleoplate. This sequence is represented by amarine shallow-water platform that experienced a sag phase followed by a rift phase in the Upper Espinhaço.We used combined sedimentological-stratigraphic descriptions of sections, whole-rock (WR) geochemistry and U-Pb detrital zircon dating to develop a regional paleogeographic evolution model of the sag phase. The succession corresponds to transgressive-regressive cycles in the following ascending order: 1) offshore to lower shoreface facies represented by quiescent periods and episodic sediment supply (Santa Rita Formation); 2) upper shoreface to foreshore and coastal desert facies with a reworking of the underlying units (Córrego dos Borges Formation); 3) lower shoreface with fallout of suspended fine sediments and a combination of unidirectional and oscillatory flows generated by storm waves (Córrego da Bandeira Formation); 4) tidal-influenced upper shoreface to foreshore facies with the migration of subaqueous dunes, wave swash in a beach environment and cycles of neap-spring tides (Córrego Pereira Formation); and 5) the resumption of lower-shoreface sedimentation and the subsequent development of a stromatolitic carbonate-siliciclastic platform (Rio Pardo Grande Formation). The geochemical data indicate that the studied units contain input from felsic rocks and sedimentary rocks. The basal marine to eolian sediments of the Galho do Miguel Formation are dominated by Rhyacian sources (2.1 Ga). The basal and intermediate units of the Conselheiro Group contain Archean, Rhyacian, Statherian and Calymmian-Ectasian (1.6–1.33 Ga) zircon grains, whereas Orosirian (1.9–2.0 Ga) sources dominate in the upper strata of the group. The study of this Stenian (Mesoproterozoic) intracratonic sequence provides clues to understanding the history of sedimentation and the potential source areas on the São Francisco Craton and adjacent areas, which are very useful for comparison to Phanerozoic intracratonic basins and the reconstruction of Paleoproterozoic and Mesoproterozoic supercontinents.Item Roteiro da excursão geológica no Quadrilátero Ferrífero e regiões adjacentes.(1992) Endo, Issamu; Rosière, Carlos Alberto; Chemale Júnior, FaridItem Sedimentological and paleoenvironmental constraints of the Statherian and Stenian Espinhaço rift system, Brazil.(2013) Santos, Marcelo Nascimento dos; Chemale Júnior, Farid; Dussin, Ivo Antonio; Martins, Maximiliano de Souza; Assis, Tiago A. R.; Jelinek, Andréa Ritter; Guadagnin, Felipe; Armstrong, RichardThe Espinhaço Basin in eastern Brazil contains depositional sequences developed in the São Francisco paleoplate and its margins. Detailed mapping was conducted and combined with U–Pb detrital zircon dating to determine the sedimentological-stratigraphic framework, provenance and minimum and maximum ages of the syn-rift-deposits. The two cycles have minimum ages of 1192 and 923 Ma and maximum ages of 1785 and 1685 Ma. The first depositional cycle, represented by the Bandeirinha and São João da Chapada formations, is marked by contributions of Neoarchean and Paleoproterozoic detrital zircons. The second cycle, the diamond-bearing Sopa-Brumadinho Formation, also contains Mesoproterozoic zircons formed between 1300 and 1190 Ma, which suggests an additional external source of Grenvillian age, that was not previously recorded in the São Francisco Craton. The investigation of such Mesoproterozoic intraplate sedimentary records, provides clues to understanding the history of the Rodinia active margins and, therefore, the kinematic reconstruction of its paleoplates.