O Stock Serra da Acauã: um exemplo de granito tipo I fracionado oxidado no Domínio Rio Piranhas-Seridó, NE do Brasil

The Serra da Acauã Stock is inserted in the context of Ediacaran plutonic activity, one of the most important geological features of the Borborema Province, NE of Brazil. The body is divided into two facies: one fine to medium equigranular and other medium to weakly porphyritic unequigranular with K-feldspar phenocrysts. U-Pb determinations in zircon indicated an ediacaran age of c. 578 Ma for its crystallization. Petrographically, the stock consists of hololeucocratic to leucocratic biotite-monzogranites (M = 1.3% – 9.9%), with biotite being the main mafic (0.5 to 8.1%). Opaque minerals, titanite, allanite, apatite and zircon are accessories and the earliest mineral phases. Geochemically, the rocks that form the stock are similar, with a weakly peraluminous character (1.00 ≤ A / CNK ≤ 1.04), with normative corundum and transition signature between alkaline and calc-alkaline rocks. The variation of the amount of oxides and trace elements suggests the fractionation of plagioclase, biotite, titanite, apatite and magnetite during crystallization of magma. The diagram for the rare earth element (REE) groups shows the enrichment of the LREE relative to the HREE, with the LaN/YbN ratios between 16.10 and 54.75, and negative anomalies of Eu (Eu/Eu* of 0.66 to 0.90) compatible with plagioclase fractionation. Data related to the temperature of zircon saturation added to geochemical discriminant diagrams have the potential to associate these rocks to a highly fragmented type I granites. The data set allows correlating the magmatism in the context of high-K calc-alkaline granites, late to post-tectonics of Piranhas-Seridó River Domain.O Stock Serra da Acauã está inserido no contexto da atividade plutônica ediacarana, uma das mais importantes feições geológicas na Província Borborema, Nordeste do Brasil. O corpo está dividido em duas fácies: uma equigranular fina a média e outra inequigranular média a fracamente porfirítica com fenocristais de K-feldspato. Determinações U-Pb em zircão apontaram uma idade ediacarana de c.a 578 Ma para a sua cristalização. Petrograficamente, o stock consiste de um biotita monzogranitos hololeucocráticos a leucocráticos (M = 1,3 – 9,9%), com biotita sendo o máfico principal (0,5 a 8,1%). Minerais opacos, titanita, allanita, apatita e zircão são acessórios e as fases minerais mais precoces. As rochas que formam o stock são geoquimicamente similares, de caráter fracamente peraluminoso (1,00 ≤ A/CNK ≤ 1,04), com coríndon normativo e de assinatura transicional entre rochas alcalinas e calcioalcalinas. A variação do conteúdo de óxidos e elementos traço sugere o fracionamento de plagioclásio, biotita, titanita, apatita e magnetita durante a cristalização do magma. O diagrama para elementos terras raras mostra enriquecimento dos elementos terras raras leves em relação aos elementos terras raras pesados, com razões LaN/YbN entre 16,10 e 54,75, e anomalias negativas de Eu (Eu/Eu* de 0,66 a 0,90) compatíveis com fracionamento de plagioclásio. Dados referentes à temperatura de saturação de zircão somados a diagramas discriminantes geoquímicos permitem associar essas rochas a granitos tipo I altamente fracionados. O conjunto de dados permite correlacionar o magmatismo no contexto de granitoides calcioalcalinos de alto potássio, tardi a pós-tectônicos do Domínio Rio Piranhas-Seridó

STOCK NOVA CRUZ (DOMÍNIO SÃO JOSÉ DO CAMPESTRE, PORÇÃO NE DA PROVÍNCIA BORBOREMA): GEOLOGIA E PETROGRAFIA

O Stock Nova Cruz (SNC) localizado na porção SSE do Domínio São José do Campestre, possui uma área aflorante em torno de 12 km2 e uma forma aproximadamente subcircular, é intrusivo em ortognaisses tonalíticos a monzograníticos pertencentes ao Complexo Serrinha - Pedro Velho de idade riaciana (c.a 2,2 Ga). Composicionalmente as rochas do stock são monzogranitos leucocráticos (minerais máficos entre 6,9 a 9,2%), tendo a biotita como máfico principal (entre 3,3 a 4,3%) e titanita, allanita, minerais opacos, epídoto, apatita e zircão como demais acessórios. Baseado em critérios de campo é possível inferir que o alojamento deste corpo se deu possivelmente em ambiente Tardi a Pós-tectônico no contexto da orogênese Brasiliana/Panafricana, submetido a um campo de stress em regime frágil em nível crustal raso. O Stock ainda apresenta evidências de que a cristalização do magma se deu principalmente de forma fracionada, com a presença de volume considerável de fluidos tardimagmáticos enriquecidos em voláteis (H2O e CO2) responsáveis pelo desenvolvimento de fases minerais secundárias (clorita, mica branca e carbonato) além do desenvolvimento relativamente extensivo de texturas mirmequíticas e granofíricas

Riacian Augen gneisses in Piranhas River-Seridó Domain - Borborema Province, Brazil Northeast

Augen gnaisses da Serra da Formiga/Fazenda Genezaré, borda do Núcleo São Vicente-Florânia (RN) e corpos a SW/NW da cidade de São José do Seridó (RN) foram estudados através de mapeamento geológico, petrografia, litogeoquímica e datação U-Pb. Estes são constituídos por biotita augen gnaisses e ortognaisses grossos graníticos/granodioríticos, leucocráticos, de textura porfirogranoblástica e cor cinza clara/rosa. A mineralogia é dada por microclina pertítica, oligoclásio, quartzo, além de biotita e anfibólio, tendo como acessórios epidoto, titanita, clorita, minerais opacos, apatita, zircão e allanita. As relações petrográficas/texturais indicam que estes atingiram a fácies anfibolito com retrometamorfismo para xisto verde. Apresentam foliação de baixo ângulo de direção NW-SE associada a lineações de estiramento com rake forte. Análises litogeoquímicas indicam assinatura de termos metaluminosos a peraluminosos, cálcio-alcalinos de alto potássio, orogênicos de ambiente colisional. Datações U-Pb em zircão (ICP-MS-LA) forneceram idades (intercepto superior) de 2252 ± 17 Ma e de 2171 ± 20 Ma, respectivamente para as rochas situadas a norte de Florânia (RN) e a leste de Genezaré (Caicó/RN). Neste último também foram obtidos valores de TDM de 2,84 Ga e ƐNd(0) de -20,76. Os dados obtidos permitem associar estes augen gnaisses ao Período Riaciano, com idade em torno de 2,25 a 2,17 Ga, e consequentemente ao magmatismo do Complexo Caicó.Augen gneisses occurring at the Fazenda Genezaré in the Serra da Formiga east of Caicó, at the border of the São Vicente-Florânia (RN) nucleus, and in exposures SW and NW of São José do Seridó (RN) were studied by geologic mapping, petrography, lithogeochemistry and U-Pb dating. These rocks consist of biotite augen gneisses, and granitic/granodioritic orthogneisses, with porphyro-granoblastic textures and light gray to pink colors. Their mineralogy consists of perthitic microcline, oligoclase, quartz, besides biotite and amphibole, with epidote, titanite, chlorite, opaque minerals, apatite, zircon and allanite as accessory minerals. Petrography indicates that these rocks were affected by amphibolite facies metamorphism, and a later greenschist facies retrometamorphism. They have a prominent low-angle NW-SE foliation containing a high rake stretching lineation. Lithogeochemistry indicates high-K, metaluminous to peraluminous and calc-alkaline geochemical signatures related to a collisional environment. U-Pb dating of zircon (LA-ICP-MS) provided an upper intercept age of 2252 ± 17 Ma and 2171 ± 20 Ma, for the rocks found north of Florânia (RN), and east of Genezaré, respectively. In the latter values of 2.84 Ga TDM and ƐNd(0) of -20.76 were also obtained. The data allow attribution of the augen gneisses to the Rhyacian period, and are consequently associated with to the magmatism which formed the Caicó Complex

Geochronology and structural and petrological features of the Bravo Pluton, Central Domain of the Borborema Province, Northeast Brazil : an early trans-alkaline granite in the post-collisional stage of the Brasiliano Orogeny

O Pluton Bravo (no Estado da Paraíba) constitui um stock elipsoidal formado por monzo/sienogranitos porfiríticos, enclaves dioritos e zonas híbridas. Está intrudido em gnaisses migmatíticos paleoproterozoicos do Domínio Central da Província Borborema. Os sienogranitos são metaluminosos a levemente peraluminosos, e exibem altas razões de K2O/Na2O > 1,5 e FeOt/(FeOt + MgO) > 0,86. Os dioritos possuem alto conteúdo de Zr (> 1.134 ppm), TiO2 ~ 1,6% e Nb > (49 ppm). As razões (LaN/YbN)N estão entre 14 e 19,4, e (Eu/Eu*)N, entre 0,31 e 0,37. As rochas do Pluton Bravo são moderadamente fracionadas com picos em La, Zr e forte depressão em P, Ti e menor em Sr. Os dados plotam no campo discriminante de granitos pós-tectônicos/intraplaca. As estimativas de pressão (4,4 a 6,0 Kbar) baseadas no conteúdo de Alt em anfibólio sugerem posicionamento do pluton na crosta superior a média. A temperatura do liquidus de acordo com o conteúdo de Zr e SiO2 oscilou entre 847 e 893°C, e a de cristalização, calculada pelo par anfibólio-plagioclásio, entre 581 e 785°C. Exibem idades-modelo TDM = 2,35 a 2,18 e εNd (580 Ma) = -18,32 a -17,03. A idade U-Pb (LA-MC-ICP-MS U-Th-Pb em zircão) indica cristalização ao redor de 581 ± 2 Ma. A relação entre a idade de cristalização (~ 580 Ma), as características químicas de granito tipo-A, idades-modelo Sm-Nd maiores que 2,1 Ga e a associação com regime tectônico transcorrente contrastam com outros granitos similares, porém ligeiramente mais novos (~ 570 Ma), que ocorrem nos Domínios Central, Rio Grande do Norte e no leste da Nigéria. Isso sugere que a transição do regime compressional para direcional/componente extensional precedeu no caso deste corpo evidenciando o caráter episódico e diacrônico da Orogênese Brasiliana. ­Conclui-se que o Pluton Bravo constitui um bom exemplo de magmatismo pós-colisional transalcalino no Domínio Central, que, com outros exemplos no Domínio Rio Grande do Norte e no leste da Nigéria, sugere um afinamento convectivo da litosfera subcontinental entre 580 e 570 Ma durante a consolidação do Supercontinente Gondwana.The Bravo Pluton (State of Paraíba) is an ellipsoidal stock formed by porphyritic monzo/syenogranites, dioritic enclaves and their hybrid products. The granitic body is intruded in paleoproterozoic gneiss-migmatitic rocks of the Central Domain of the Borborema Province. The monzo/syenogranites are metaluminous to slightly peraluminous and exhibit high K2O/Na2O > 1.5 and FeOt/(FeOt + MgO) > 0.86. The diorites exhibit high contents of Zr (> 1,134 ppm), TiO2 ~ 1.6% and Nb > (49 ppm). (La/Yb)N is in between 14 and 19.4 and (Eu/Eu*)Nbetween 0.31 to 0.37. In the spiderdiagram, the data are moderately fractionated with peaks in La, Zr and strong negative anomalies in P, Ti and less in Sr. They plot in the field of post-tectonic/intraplate granites in the tectonic discriminant diagram, with some scattering. The estimated pressure (4.4 to 6.0 kbar) based on Alt content in amphibole suggest a range from the middle to the upper crust for the emplacement of the Bravo Pluton. The liquidus temperature according to Zr and SiO2 contents range from 847 to 893°C and for the crystallization, calculated by amphibole-plagioclase pairs range from 589-867°C. They show TDM model ages ranging from 2.35 to 2.18 and εNd(580 Ma) = -18.32 to -17.03. A crystallization age of 581 ± 2 Ma was obtained for the granite from LA-MC-ICP-MS U-Th-Pb method in zircon. The relationship between the crystallization age (~ 580 Ma), A-type geochemical characteristics of the granitoids, Nd model-ages greater than 2.1 Ga and association with the strike-slip regime contrasts with other similar granitoids, furthermore, slight younger in age (~ 570 Ma), which occur in Central, Rio Grande do Norte Domains and in eastern Nigeria. In this sense, the transition of the compressional to the directional regime (with an extensional component) has occurred just before in the case of this body showing an episodic and diachronic character of the Brazilian ­orogeny. We conclude that Bravo Pluton constitutes a good example of trans-alkaline post-collisional magmatism within Central Domain which together with other examples from Rio Grande do Norte Domain and in eastern Nigeria suggest a convective thinning of subcontinental lithosphere between ­580-570 Ma during amalgamation of Gondwana Supercontinent

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Caracterização de suítes magmáticas neoproterozóicas e da trama estutural da porção central da Província Borborema (NE do Brasil) através do processamento digital de imagens

Digital image processing of Landsat 5-TM images of the Província Borborema central portion linked with field data have emphasized the igneous bodies limits and the structural framework nearby Triunfo (PE), Manaíra (PB)and Princesa Isabel (PB)cities. The images interpretation allowed the distinction of four magmatic suites and their hosted complexes (Riacho Gravatá e São Caetano complexes)and the structural relations and geometric geoarchitecture of shear zone systems of Neoproterozoic ages.Pages: 279-28

The Catolé do Rocha Batholith (RN-PB): A reduced A2-type granitic magmatism in the Rio Piranhas-Seridó Domain, Borborema Province, Northeastern of Brazil

The Catolé do Rocha Batholith, situated in the Rio Piranhas-Seridó Domain of the Borborema Province (Northeastern (NE) Brazil), is an important example of the post-collisional Ediacaran magmatism that affected this region. It includes metaluminous to slightly peraluminous syenogranite and quartz syenite, basic-intermediate rocks and minor microgranite dykes; the whole set is intrusive in the Paleoproterozoic basement. This batholith has been interpreted as a member of the high-K calc-alkaline magmatic suite with chemical affinities akin to the Caledonian I-type granites. However, there are many lithochemical evidence associating the batholith to the A-type magmas. The granites are alkali-calcic to alkaline, have ferroan character, significant concentrations of large-ion lithophile elements (LILE) and high-field-strength elements (HFSE) and relative enrichment of light rare earth elements (LREE) than heavy rare earth elements (HREE). Their chemical signatures agree with a post-collisional A2-type setting. Geothermobarometric estimates provide crystallization at pressures of 4.6 – 6.3 kbar (ca. 16 – 24 km in depth) and temperatures in the range of 950 – 750°C, under low oxygen fugacity conditions (-4 &lt; ΔFQM &lt; -1). Geochemical data and distinct redox crystallization conditions for the felsic and basic-intermediate rocks suggest they represent distinct magma batches, with local mixing and mingling features. The origin of the batholith seems to be related to enriched (metasomatized) sources, with differentiation controlled mostly by fractional crystallization processes.O Batólito Catolé do Rocha, situado no Domínio Rio Piranhas-Seridó da Província de Borborema (Nordeste (NE) do Brasil), é um importante representante do magmatismo ediacarano pós-colisional que acometeu essa região. Ele inclui sienogranitos e quartzo sienitos metaluminosos a ligeiramente peraluminosos, rochas básico-intermediárias e, subordinadamente, diques e/ou bolsões de microgranitos menores. Esse batólito é tido como representante da suíte cálcio-alcalina de alto K, que inclui principalmente granitos de afinidade química próxima aos de tipo-I caledonianos. Contudo, são diversas as evidências litoquímicas que aproximam o batólito aos magmas de tipo-A. As rochas graníticas são álcali-cálcicas a alcalinas, possuem caráter ferroano, concentrações significativas de elementos litófilos de raio grande (LILE) e de alto potencial iônico (HFSE) e enriquecimento de terras-raras leves (LREE) sobre pesados (HREE). Suas assinaturas químicas permitem classificá-los como granitos de tipo‑A2 pós-colisionais. Estimativas geotermobarométricas apontam cristalização sob pressões de 4,6 – 6,3 kbar (~16 – 24 km de profundidade) e temperaturas entre 950 – 750°C, em condições de baixa fugacidade de oxigênio (-4 &lt; ΔQFM &lt; -1). Evidências químicase distintas condições redox estimadas para os granitos e rochas básico-intermediárias do batólito sugerem que se trata de magmas distintos, com misturas do tipo mixing e mingling locais. A origem do batólito parece estar relacionada a fontes enriquecidas (metassomatizadas), com diferenciação controlada principalmente por processos de cristalização fracionada

Gamma-ray spectrometry, magnetic and gravity signatures of Archean nuclei of the Borborema Province, Northeastern Brazil

Gamma-ray spectrometry, as well as magnetic and gravity data, are used to investigate the geophysical signatures of the Archean nuclei of the Borborema Province. Natural radioactivity, magnetic anomalies, and residual Bouguer gravity anomalies of the Archean nuclei exhibit distinct signatures in relation to adjacent Proterozoic domains. Gamma-ray spectrometry data reveal eTh enrichment in relation to K and eU contents in Archean units. Assuming that K and U were the dominant isotopes, this relative enrichment of eTh can be explained by the fact that Th radioisotopes have a longer half-life than the other two radionuclides and that 4.56 Ga has elapsed since Earth's formation. The intensity of the total magnetic gradient in Archean units is greater than in Proterozoic units in most nuclei. The Archean units underwent deformation and metamorphism in the Brasiliano/Pan-African Orogeny; therefore, the magnetic characteristics now observed in Archean mafic-ultramafic rocks, iron formations and gneiss-migmatite complexes are the joint result of their primary properties and the superposed effects of the orogeny. All Archean nuclei of the Borborema Province show positive residual Bouguer gravity anomalies. This could be due to the conservation of the main petrophysical properties of the Archean lithosphere, and their preservation during the intense granitization that occurred in the Brasiliano/Pan-African Orogeny. As magnetic and gravity methods provide information from depth, it is possible to infer the continuity of some Archean nuclei beyond the limits established by surface geological data. Based on these results, it will be possible to use geophysical signatures to investigate the possible existence of unknown Archean units in the province