U-Pb SHRIMP zircon dating of Grenvillian metamorphism in Western Sierras Pampeanas (Argentina) : correlation with the Arequipa-Antofalla craton and constraints on the extent of the Precordillera Terrane

The Sierras Pampeanas of Argentina, the largest outcrop of pre-Andean crystalline basement in southern South America, resulted from plate interactions along the proto-Andean margin of Gondwana, from as early as Mesoproterozoic to Late Paleozoic times (e.g., Ramos, 2004, and references therein). Two discrete Paleozoic orogenic belts have been recognized: the Early Cambrian Pampean belt in the eastern sierras, and the Ordovician Famatinian belt, which partially overprints it to the west (e.g., Rapela et al., 1998). In the Western Sierras Pampeanas, Mesoproterozoic igneous rocks (ca. 1.0–1.2 Ga) have been recognized in the Sierra de Pie de Palo (Fig. 1) (McDonough et al., 1993 M.R. McDonough, V.A. Ramos, C.E. Isachsen, S.A. Bowring and G.I. Vujovich, Edades preliminares de circones del basamento de la Sierra de Pie de Palo, Sierras Pampeanas occidentales de San Juán: sus implicancias para el supercontinente proterozoico de Rodinia, 12° Cong. Geol. Argentino, Actas vol. 3 (1993), pp. 340–342.McDonough et al., 1993, Pankhurst and Rapela, 1998 and Vujovich et al., 2004) that are time-coincident with the Grenvillian orogeny of eastern and northeastern North America (e.g., Rivers, 1997 and Corrievau and van Breemen, 2000). These Grenvillian-age rocks have been considered to be the easternmost exposure of basement to the Precordillera Terrane, a supposed Laurentian continental block accreted to Gondwana during the Famatinian orogeny (Thomas and Astini, 2003, and references therein). However, the boundaries of this Grenvillian belt are still poorly defined, and its alleged allochthoneity has been challenged (Galindo et al., 2004). Moreover, most of the Grenvillian ages so far determined relate to igneous protoliths, and there is no conclusive evidence for a Grenvillian orogenic belt, other than inferred from petrographic evidence alone (Casquet et al., 2001). We provide here the first evidence, based on U–Pb SHRIMP zircon dating at Sierra de Maz, for a Grenville-age granulite facies metamorphism, leading to the conclusion that a continuous mobile belt existed throughout the proto-Andean margin of Gondwana in Grenvillian times

Datações U-Pb convencional versus SHRIMP do Maciço estanífero Santa Bárbara, Suíte Granitos últimos de Rondônia, Brasil

The Santa Bárbara Granite Massif is part of the Younger Granites of Rondônia (998 - 974 Ma) and is included in the Rondônia Tin Province (SW Amazonian Craton). It comprises three highly fractionated metaluminous to peraluminous within-plate A-type granite units emplaced in older medium-grade metamorphic rocks. Sn-mineralization is closely associated with the late-stage unit. U-Pb monazite conventional dating of the early-stage Serra do Cícero facies and late-stage Serra Azul facies yielded ages of 993 ± 5 Ma and 989 ± 13 Ma, respectively. Conventional multigrain U-Pb isotope analyses of zircon demonstrate isotopic disturbance (discordance) and the preservation of inherited older zircons of several different ages and thus yield little about the ages of Sn-granite magmatism. SHRIMP U-Pb ages for the Santa Bárbara facies association yielded a 207Pb/206Pb weighted-mean age of 978 ± 13 Ma. The textural complexity of the zircon crystals of the Santa Bárbara facies association, the variable concentrations of U, Th and Pb, as well as the mixed inheritance of zircon populations are major obstacles to using conventional multigrain U-Pb isotopic analyses. Sm-Nd model ages and µNd (T) values reveal anomalous isotopic data, attesting to the complex isotopic behaviour within these highly fractionated granites. Thus, SHRIMP U-Pb zircon and conventional U-Pb monazite dating methods are the most appropriate to constrain the crystallization age of the Sn-bearing granite systems in the Rondônia Tin Province.O Maciço Granítico Santa Bárbara é parte da Suíte Granitos Últimos de Rondônia (998 - 974 Ma), e integra a Província Estanífera de Rondônia (SW do Cráton Amazônico). Compreende três unidades de granitos altamente fracionados, metaluminosos a peraluminosos, de afinidade geoquímica com granitos do tipo A e intraplaca. A mineralização estanífera está associada com a unidade tardia. As unidades facies Serra do Cícero, precoce, e facies Serra Azul, tardia, foram datadas por U-Pb em monazita em 993 ± 5 Ma e 989 ± 13 Ma, respectivamente. A datação U-Pb convencional de zircão, entretanto, demonstrou perturbação isotópica e revelou importantes componentes herdados das unidades em questão, sendo inadequada para a definição da idade de cristalização desses granitos. Datações via SHRIMP do zircão da unidade associação de facies Santa Bárbara forneceram média ponderada das idades 207Pb/206Pb de 978 ± 13 Ma. A alta complexidade textural dos cristais de zircão da associação de facies Santa Bárbara, seus teores variáveis de U, Th e Pb, além da presença comum de populações de zircão com núcleos herdados, desencorajam o uso da datação U-Pb convencional em multigrão em granitos similares. As idades-modelo Sm-Nd e os valores de µNd (T) revelam dados isotópicos anômalos, confirmando a complexidade do comportamento dos sistemas isotópicos nestes granitos altamente fracionados. Diante desse cenário, os autores consideram os métodos U-Pb em zircão via SHRIMP e U-Pb convencional em monazita como mais adequados para a estimativa da idade de cristalização em sistemas graníticos mineralizados na Província Estanífera de Rondônia

Fatores que influenciam a amamentação à alta em recém-nascidos após o internamento numa unidade de apoio perinatal diferenciado

Introdução: O leite materno é um alimento vivo, completo e natural, adequado a todos os recém-nascidos, salvo raras exceções, sendo uma das formas mais eficientes de suprimir necessidades nutricionais, imunológicas e emocionais do bebé, ainda com maior relevo nos Recém-nascidos doentes e internados em Neonatologia. Inúmeras estratégias hospitalares têm sido implementadas com o objetivo de valorizar a amamentação de recém-nascidos doentes nas Unidades de Apoio Perinatal Diferenciado, promovendo a amamentação e o vínculo afetivo da díade mãe-bebé. Objetivos: Identificar a relação entre as características sociodemográficas maternas, as variáveis obstétricas e clínicas do Recém-Nascidos e os conhecimentos e dificuldades das mães na amamentação à alta de recém-nascidos internados numa Unidade de Apoio Perinatal Diferenciado; Identificar os fatores maternos e do Recém-Nascido que se relacionam com a amamentação á alta do recém-nascidos internados numa Unidade de Apoio Perinatal Diferenciado. Metodologia: Estudo quantitativo, do tipo descritivo analítico-correlacional de corte transversal, realizado numa amostra não probabilística, composta por 100 mães, com média de idade de 29,63 anos (DP= 5,395) que acompanhavam os seus filhos numa Unidade de Apoio Perinatal Diferenciado num hospital público do Norte de Portugal. Para a recolha de dados utilizou-se um questionário de autorrelato da vivência das mães sobre a amamentação, desenvolvido por Sousa (2014). Resultados: Registou-se um predomínio de mães com o 2º e 3º ciclo do ensino básico, empregadas, a viver numa zona urbana, com companheiro. Do ponto de vista obstétrico, 56% tiveram parto distócico, 69% não frequentaram aulas de preparação para o parto e 51% tinham apenas aquele filho. Clinicamente os bebés nasceram de termo 61% e a patologia mais frequente foi o Risco Infecioso, seguida da prematuridade (32%). Todas as mães consideram que a Unidade de Apoio Perinatal Diferenciado promove a Amamentação e consideraram os enfermeiros como o profissional mais indicado para prestar apoio (92%) e esclarecer as dúvidas (96%). O nível de conhecimentos sobre amamentação foi classificado como suficiente para 48% das mães e 53% apresentaram dificuldades com a amamentação. O estudo revelou ainda que os conhecimentos eram mais elevados nas mães com ensino superior, que tiveram um parto distócico, que tinham apenas um filho, nas mães de recém-nascidos com outras patologias e nas que não tinham amamentado anteriormente. As dificuldades evidenciaram-se nas mães que tiveram parto eutócico e nas que tiveram um filho macrossómico. Conclusão: A passagem do conhecimento do profissional para a capacitação da mãe para a amamentação, sobretudo perante um bebé com patologia é uma tarefa árdua a ser ultrapassada. Os profissionais de saúde deverão iniciar uma reflexão conjunta sobre as suas práticas e formação sobre aleitamento materno, confrontando as simetrias e\ou assimetrias entre os pontos de vista dos enfermeiros e utentes, para melhor serem ultrapassadas as dificuldades. PALAVRAS-CHAVE: Aleitamento materno; Conhecimentos; Dificuldades; Enfermeiros; Mães; Neonatologia.Abstract Background: Breast milk is a living, complete and natural food suitable for all newborns, with rare exceptions, being one of the most efficient ways of suppressing the nutritional, immunological and emotional needs of the baby, even more important in sick babies admitted in a Neonatology unit. Numerous hospital strategies have been implemented with the objective of valuing breastfeeding of sick newborns in the Differentiated Perinatal Support Units, promoting breastfeeding and the affective bond of the mother-baby dyad. Objectives: To identify the relationship between maternal sociodemographic characteristics, obstetric and clinical variables of the Newborn and the knowledge and difficulties of mothers in breastfeeding newborns hospitalized in Differentiated Perinatal Support Units; to identify maternal and Newborn factors related to breastfeeding at the discharge of newborns hospitalized in a Differentiated Perinatal Support Units. Methodology: A quantitative, cross-sectional, descriptive and correlational study was performed in a non-probabilistic sample, composed of 100 mothers, with mean age of 29.63 years (SD = 5,395) who followed their children in a Differentiated Perinatal Support Unit in a public hospital in northern of Portugal. For data collection we used a self-report questionnaire of experience living of mothers about breastfeeding, developed by Sousa (2014). Results: There was a predominance of mothers with the 2nd and 3rd cycle of basic education, employed, living in an urban area with a partner. From the obstetric point of view, 56% had dystocia delivery, 69% did not attend childbirth classes and 51% had only that child. Clinically 61% of babies were born in term pregnancy and the most frequent pathology was Infectious risk, followed by prematurity (32%). All mothers consider that the Differentiated Perinatal Support Unit promotes Breastfeeding and the nurses to be the most appropriate professional to provide support (92%) and clarify doubts (96%). The level of knowledge about breastfeeding was classified as sufficient for 48% of mothers and 53% presented difficulties with breastfeeding. The study also revealed that knowledge was higher in mothers with higher education, who had a single child, with dystocia delivery, in mothers of newborns with other health conditions and those who had not previously breastfed. The difficulties were evidenced in mothers who had eutocic delivery and those who had a overgrowth baby. Conclusion: The crossover from the knowledge of the professional to the skills training in mothers for breastfeeding, especially when the baby has pathology, is an arduous task to be overcome. Health professionals should initiate a joint reflection on their practices and training on breastfeeding, comparing the symmetries and / or asymmetries between the points of view of nurses and users, in order to better overcome the difficulties. Keywords: Breastfeeding; Knowledge; Difficulties; Nurses; Mothers; Neonatology

El complejo volcánico cerros Bravos, región de Maricunga, Chile: Geología, alteración hidrotermal y mineralización

El Complejo Volcánico Cerros Bravos (Oligoceno-Mioceno) es un conjunto de lavas y domos dacítico-andesíticos calcoalcalinos de gran extensión (450 km2) ubicado a unos 140 km al este de Copiapó, Chile, que integra la Franja de Maricunga, cadena volcánica neógena que representa un arco pluto-volcánico de margen continental. Los análisis radiométricos K-Ar señalan que el complejo volcánico Cerros Bravos estuvo activo entre los 26-18 Ma (Oligoceno-Mioceno inferior) en tanto que el complejo La Coipa registra actividad hasta el Mioceno medio (15 Ma), y desde allí hacia el sur los centros volcánicos presentan edades entre 16 y 6 Ma. El complejo hospeda la zona de alteración hidrotermal del Prospecto Esperanza, sistema epitermal del tipo sulfato-ácido con mineralización de oro y plata controlada estructuralmente y asociada a una intensa silicificación y argilización con calcolinita, alunita y jarosita, con edades radiométricas K-Ar entre 20-18 Ma. Los estudios isotópicos de Pb realizados en rocas y sulfuros de los depósitos de la Franja de Maricunga indican que las rocas ígneas del Oligoceno-Mioceno son una mezcla de manto subcortical máfico o material cortical y material cortical radiogénico. El Pb en los depósitos de metales preciosos de la franja es dominado por una fuente como las rocas ígneas huéspedes y, localmente, otras rocas huéspedes (sedimentarias triásicas) pueden haber contribuido con Pb durante la circulación hidrotermal en ambiente cercano a la superficie. La aplicación de las metodologías de la teledetección en imágenes Landsat TM en la zona de Maricunga demostró ser una herramienta eficaz para la exploración ya que permitió destacar perfectamente las zonas de alteración hidrotermal presentes en el área y la elaboración de mapas de alta confiabilidad a escala regional

Summary of Pb isotopic compositions in epitermal precios metal deposits, Orcopampa área of Southern Peru, Berenguela area of Western Bolivia, and the Maricunga belt in north-central Chile

The Mesozoic and Cenozoic Central Andes are divided into three Pb isotopic provinces, based upon the Pb isotopic compositions of ore minerals (MacFarlane et al., 1990). Macfarlane et al., 0990), furthermore, argue that the Pb isotopic compositions of the ore minerals reílect those of the igneous rocks associated with the deposits. Province I lies along the coast of Perú, Chile, and westernmost Bolivia. Mcsozoic and early Cenozoic volcapic and plutonic ares built upon a rifted and thinned continental margin dominate this province. Three subprovinces are distinguished based upon slight differences in Pb isotopic compositions. Province la includes northern and central Chile south of 19°S; province lb includes central Perú north of 13°S; whereas province le includes central and southern Perú between the two other subprovinces. Province II lies in the high Andes of central Perú and, perhaps, in northern Chile and Argentina, where miogeoclinal sedimentary rocks crop out and the crust underwent a lower magnitude of extension in the early Mesozoic. This region generally represents a back-arc position relative to the Mesozoic and early Cenozoic magmatic ares, and extensive magmatism related to the Andean cycle has only occurred since the Oligocene. Paleozoic ares are the dominant basement in this province. Province III lies in the Cordillera Oriental and Altiplano of Perú and Bolivia where Paleozoic, Mesozoic, and Cenozoic sedimentary rocks are multiply dcformed by thrust faults. Magma ti-e episodes of Triassic to Jurassic and Oligocene to Miocene age are documented. Proterozoic rocks of the Brazilian shicld are underthrust beneath the Cordillera Oriental, with the youngest shortcning episode beginning in the Oligocene. Province III is subdivided into two subprovinces: ma lies in southeastern Perú where both episodes of magmatism occurred, whereas IIIb lies in Bolivia where magmatism is primarily of Oligocene and Miocene age. Pb isotopic compositions for Province I are slightly less radiogenic than those from province II, whereas province III isotopic compositions are much more varied with consistently higher 207Pb/ 204pb and 208pb/204pb at a given 206pb/ 204pb_Province I Pb isotopic compositions (206pb/ 204pb =18.21-18.82; 207Pb/2<YíPb = 15.55-15.69; 2º8Pb/2º4Pb = 38.11-38.95) overlap with and extend below the average crustal growth curve of Staccy and Kramers (1975) on the uranogenic diagram (207pb/204pb versus 206pb/204Pb). Province lT Pb isotopic compositions (206pb/2<Yípb = 18.76-18.90; 207pb/204pb 15.62-15.73; 208pb/204pb 38.63-39.16) and Province III Pb isotopic compositions (206pb/204Pb 17.97-25.18; 207pb/204pb 15.51-16.00; 208pb/20/4pb 37.71-40.07) lie above the average crustal growth curve on the same diagram. The Pb isotopic compositions from these last two provinces require contribution from a high mu (238U/204pb) Proterozoic or Archean source. On the thorogcnic Pb isotopic variation diagram (208Pb/ 204Pb versus 206pb/204pb), isotopic compositions for province I, 11, and IIIa scatter along the average crustal growth curve of Stacey and Kramers (1975-) indicating that a time averaged Th/U ratio - 4 (the average cristal value) characterizes the Central Andes. Pb isotopic compositions for province IIIb are the most radiogenic and also the most heterogeneous. The variable radiogenic Pb isotopic compositions of province III suggcst heterogeneous upper cristal sources, whereas the isotopic compositions of province I probably reflect a mafic cristal lithospheric source, probably modified by subduction processcs. Province II isotopic compositions conceivably represent a mix betwecn the two model reservoirs

Note – Preserving Dignity in Due Process

Procedural due process is a guarantee of fairness. Fundamentally, this guarantee requires notice and an opportunity to be heard. Procedural protections from arbitrary state action vary according to the context of each case, and protections in administrative actions are distinct from those provided in formal judicial proceedings. The administrative state developed to address a pressing need: how to govern and regulate when the three branches of government lack the capacity to efficiently and effectively administer an everevolving society. But as society has developed and expanded, individuals have more frequently interacted with the administrative state, in turn necessitating the expansion of procedural due process into an area of law that prioritizes efficiency over individual rights. Both the United States Supreme Court and the California Supreme Court have addressed this tension, but with different emphases. Where the U.S. Supreme Court applies a narrow constitutional threshold for rights implicating procedural protections, the California Supreme Court applies a more expansive threshold, with a particular focus on the dignity of the individual confronted with an adverse state action. Where the U.S. Supreme Court uses a three-factor balancing test for procedural adequacy, the California Supreme Court has articulated a four-factor balancing test that recognizes a person’s dignitary interest in procedural protections against the state. However, California’s due process analysis has been applied haphazardly, at best, leading to confusion amongst appellate courts. This Note argues that uneven application of the doctrine stems from unclear guidance from the California Supreme Court in the first instance and, ultimately, demeans the dignitary interest. After outlining the federal and state frameworks and explaining the misapplication of the California due process tests by the state’s courts, this Note urges a clearer definition of the due process trigger and more vigorous consideration of the dignitary interest in order to achieve a truer appreciation for and greater protection of an individual’s position before a state actor