Terrane transfer during the Grenville orogeny: tracing the Amazonian ancestry of southern Appalachian basement through Pb and Nd isotopes

Whole rock Pb isotope data can be used to determine the provenance of different blocks within the Rodinia supercontinent, providing a test for paleogeographic reconstructions. Calculated isotopic values for the source region of the Grenville-deformed SW Amazon craton (Rondonia, Brazil), anchored by published U-Pb zircon ages, are compared to those from the Grenville belt of North America and Grenvillian basement inliers in the southern Appalachians. Both the SW Amazon craton and the allochthonous Blue Ridge/Mars Hill terrane are defined by a similar Pb isotopic signature, indicating derivation from an ancient source region with an elevated U/Pb ratio. In contrast, the Grenville Province of Laurentia (extending from Labrador to the Llano Uplift of Texas) is characterized by a source region with a distinctly lower, time-integrated U/Pb ratio. Published U-Pb zircon ages (ca. 1.8 Ga) and Nd model ages (1.4-2.2 Ga) for the Blue Ridge/Mars Hill terrane also suggest an ancient provenance very different from the rest of the adjacent Grenville belt, which is dominated by juvenile 1.3-1.5 Ga rocks. The presence of mature continental material in rocks older than 1.15 Ga in the Blue Ridge/ Mars Hill terrane is consistent with characteristics of basement rocks from the SW Amazon craton. High-grade metamorphism of the Blue Ridge/Mars Hill basement resulted in purging of U, consistent with observations of the rest of the North American Grenville province. In contrast, the Grenvillian metamorphic history of the Amazon appears to have been much more heterogeneous, with both U enrichment and U depletion recorded locally. We propose that the Blue Ridge/ Mars Hill portion of the Appalachian basement is of Amazonian provenance and was transferred to Laurentia during Grenvillian orogenesis after similar to1.15 Ga. The presence of these Amazonian rocks in southeastern Laurentia records the northward passage of the Amazon craton along the Laurentian margin, following the original collision with southernmost Laurentia at ca. 1.2 Ga. (C) 2004 Elsevier B.V. All rights reserved.

Systematic consideration of petiole anatomy of species of Echinodorus Richard (Alismataceae) from north-eastern Brazil

Petiole anatomy of the north-eastern Brazilian species Echinodorus glandulosus, E. palaefolius, E. pubescens, E subalatus, E lanceolatus and E paniculatus were examined. All species had petioles with an epidermis composed of tabular cells with thin walls. The chlorenchyma just below the epidermis alternates with collateral vascular bundles. The interior of the petiole is filled by aerenchyma with ample open spaces or lacunas. The lacunas are bridged at intervals by plates, or by diaphragm-like linkages. There are lactiferous ducts and groups of fibres throughout the entire length of the petiole, but more frequently in the chlorenchyma. Important taxonomic characteristics for the genus Echinodorus include the shape and outline of the petiole in transversal section, the presence of winged extensions, and the number of vascular bundle arcs. Exceptions occur in E. lanceolatus and E. paniculatus, whose petioles have similar anatomic patterns. A comparative chart of the petiole anatomic characteristics analyzed is presented. (c) 2007 Elsevier GmbH. All rights reserved.

A personagem Bigger Thomas na obra de Richard Wright e a construção de identidade afro-americana

This paper analyzes the character Bigger Thomas Native Son’s American novel published in 1940 by African-American author Richard Wright. Through this character we try to study more the post-slavery racial issue in a country where racial segregation was legally sustained and how this issue was reflected in society and identity formation of their native sons African-American

Estudo do método Monte Carlo e sua aplicação no modelo SIR

In this work we present a discussion and the results of the simulation of disease spread using the Monte Carlo method. The dissemination model is the SIR model and presents as main characteristic the disease evolution among individuals of the population subdivided into three groups: susceptible (S), infected (I) and recovered (R). The technique used is based on the introduction of transition probabilities S-> I and I->R to do the spread of the disease, they are governed by a Poisson distribution. The simulation of the spread of disease was based on the randomness introduced, taking into account two basic parameters of the model, the power of infection and average time of the disease. Considering appropriate values of these parameters, the results are presented graphically and analysis of these results gives information on a group of individuals react to the changes of these parameters and what are the chances of a disease becoming a pandemic

Tradução anotada, autor-tradutor invisível: Richard Francis Burton na Brasiliana

The aim of this paper is to analyze the translation of the work by the translator-traveller Richard Francis Burton, Explorations of the Highlands of the Brazil, with a full account of the gold and diamond mines, made by Américo Jacobina Lacombe, trying to relate the work of the latter to the editorial goals of the Brasiliana Collection. As a subseries of the Biblioteca Pedagógica Brasileira [Brazilian Pedagogical Library] published by Companhia Editora Nacional, Brasiliana was conceived in agreement with the 1930s and 1940s policies to expand lay education and make it possible for Brazilians to get to better know the greatness of their country. The paper will focus on the numerous translator’s notes, since many of them reveal Lacombe’s didactic purpose of informing readers about Brazilian history and geography. The analysis also examines the effacement of Burton’s translations from Portuguese into English in his book.

Intoxicação pela Metáfora segundo Gilles Deleuze e Félix Guattari: os desenhos do pequeno Richard (1941)

Starting with a critical review that make Deleuze and Guattari about the use of images in the writings and drawings reproduced in Narrative of a Child Analysis, by Melanie Klein, the authors reflect on the place of metaphor in the speech of this analyzed child about desiring life, intoxicated with Oedipian metaphors. They highlight the role of metaphor in the production of the alleged psychoanalytic intoxication.