Study of the veins, alterations and mineralization of the Comtois gold deposit, Abitibi subprovince, Quebec, Canada

Le gîte de Comtois est situé dans le complexe volcanique archéen du Nord de la sous province de l'Abitibi. Les roches volcaniques hôtes sont de compositions mafiques, intermédiaires et felsiques. La séquence volcanique est verticalisée. Elle montre des textures massives et clastiques. Comtois se caractérise par ses nombreux dykes, des veines et des altérations hydrothermales. Cette étude vise à découvrir un lien entre la minéralogie des veines, les altérations hydrothermales et la minéralisation aurifère afin d'identifier le type de modèle génétique. L'étude des veines a permis d'établir quatre types sur la base de leur paragenènes et leur orientation. Les veines de type I sont composées de quartz gris d'orientation variable. Les veines de type II sont composées d'actinote + quartz ± épidote ± pyrite orientée 60°N et 100°N. Les veines de type III sont composées de pyrite ± chalcopyrite orientée 120°N. Les veines de type IV sont composées de quartz laiteux orienté 70°N. Les roches volcaniques ont subi plusieurs altérations hydrothermales. La cordiérite et andalousite sont trouvées de façon envahissante partout dans la zone d'étude. L'épidote et l'albite sont associées aux veines de type II. Une enveloppe d'altération à quartz est localement observée avec les veines de type III. La minéralisation en or est associée aux veines de types III dans l'enveloppe d'altération siliceuse. L'or se trouve en grain d'électrum dans la pyrite et ses fractures. Le ratio Au:Ag se situe entre 9:1 et 1:2. Des grains de BiTe sont aussi présents dans le même contexte. Le contexte géologique, les altérations hydrothermales et la composition des grains d'électrum sont consistants avec un modèle génétique de type sulfures massifs volcanogène. \ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Altération, Cordiérite, Andalousite, Veines, Sulfures Massif

Culture or Biology? If this sounds interesting, you might be confused

Culture or Biology? The question can seem deep and important. Yet, I argue in this chapter, if you are enthralled by questions about our biological differences, then you are probably confused. My goal is to diagnose the confusion. In debates about the role of biology in the social world it is easy to ask the wrong questions, and it is easy to misinterpret the scientific research. We are intuitively attracted to what is called psychological essentialism, and therefore interpret what is biological as what can be traced to “essences”. On this interpretation, it would be deep and important to know what about, say, the differences between the genders is biological: it would correspond to what is essential to being a man or being a woman, and be opposed to what is a mere accidental feature that some women or some men have. Yet, the psychological essentialist understanding of ‘biological differences’ is deeply mistaken about biology. It has the wrong conception of biological kinds, of biological heritability, and of how genes and hormones work. Those who argue for an important role of ‘biology’ in the explanation of human differences often see ‘the science’ on their side. But this is false – on the interpretation of ‘biological differences’ that is most intuitive and that makes the question appear to be most interesting. Defenders of ‘biology’ often have the science against them. What is often called ‘biology’ is a myth: a myth created by an intuitive tendency that grotesquely distorts real biological research

Hydrogeochemistry in soils and sediments in the area of the Lagoa Campestre lake (Salitre, MG, Brazil) : chemical balances of major and trace elements and dynamics of rare earth elements

Study of the sediments filling the Lagoa Campestre peaty lake (Minas Gerais, Brazil) showed a high rare earth elements (REE) content, especially in phosphatic bottom beds (authigenic phosphates), whose fluctuations could be related to variations in the erosion conditions and the nature of the plant cover. In order to understand better the mode of complexation and transport of trace elements in this environment, a geochemical survey was undertaken of the waters of the area, both in surface streams and at the water table. The concentration of the main cations decreases from the top of the slope down towards the lake. This is especially true during the rainy season and could be related to a more active leaching in this period. The chondrite-normalized REE pattern in the soil sequence is very similar to the pattern found for the local bedrock and is characterized by a depletion in heavy REE (HREE). For the groundwaters, the REE abundance normalized to average REE values of soils shows an enrichment in HREE as well as downslope, near the lake, and in the upper part of the sequence. At the outlet of the lake, the water of the stream has an alkaline pH and high values for numerous elements, contrasting with the low contents in the water table and in the lake. Thus it seems that the water of the outlet could be at least partly related to an apatite rich and carbonatitic formation, more abundant in this area. This is confirmed by positive Sm and Eu anomalies. Waters were also collected in 2 types of lysimeters. The cylindrical collectors gave higher REE contents than the plate collectors, a feature that might result from adsorption by the metabolic activity at the rhyzosphere. The geochemical data acquired in the groundwaters, in the lake and at the outlet of the Lagoa Campestre allow a better understanding of the dynamics of the basin. (D'après résumé d'auteur

Human action in a Genomic Era: debates on human nature Ação humana na Era do Genoma: debates sobre a natureza humana

The supposed properties of 'genes' have led natural scientists to claim authority to explain the reasons of human action, behavior, and even human nature, which has traditionally been the object of study of the humanities. The aim of this paper is to discuss the possibilities of sociological theory dealing with the biological reductionism that establishes the strict articulation between 'human nature' and 'human action', presented in several speeches and papers by scientists and journalists and supported by features of 'genes'. I intend to argue that sociological theories may broaden their scope of analysis by encompassing biological dimensions, which does not necessarily mean adopting a biological reductionist approach.<br>As supostas propriedades dos 'genes' levam os cientistas naturais a reivindicar autoridade para explicar as razões de atos, comportamentos e até a natureza humana, tradicional objeto de estudo das ciências humanas. O objetivo deste artigo é discutir as possibilidades de a teoria sociológica lidar com o reducionismo biológico, que estabelece uma articulação exata entre 'natureza humana' e 'ação humana'. Tal reducionismo está presente em discursos e artigos de cientistas e jornalistas, e é embasado por características dos 'genes'. Argumento que as teorias sociológicas podem ampliar suas possibilidades de análise se incorporarem dimensões biológicas, o que não implica necessariamente adotar uma abordagem reducionista