Recebido em 15/9/05; aceito em 25/4/06; publicado na web em 30/8/06Lateritic iron crust (LIC) samples from Padauari (AM) were analysed by XRD, optical microscopy and SEM-EDS. The equilibrium of iron minerals (IM) was studied using Eh-pH diagram
TH E PRECAMBRIAN OF NATI VID ADE REGIO N, GOlAS, BRAZIL. Thi s~per presents the results of the geological in vestigation performed on the Preca mbrian rock s at the Nativi dede regio n (Northe rn Goi4s). Archean tcnalites, mafic rock s, and supracrus tals of ancient evolution not yet reconstituted were modified by strong progressive non-coaxial ductil e deformation, with displacement, imbrication. sheari ng. recrytallizatioh in high to medium amphi bolit e facies. and some migma tiza tio n. These mod ified rocks gra de to gra nite-greenstone terrai n in the easte rn part of the area . All these modified rocks and unaffected gneisses are assembled in the Goiano Complex . The mass displacement occurred towards SSE and the myloniti c foliation has ON30 d irection, what is interpreted as related to a not yet located oblique ramp . This impo rtant tectoni c event is adm ited to be of Late Archean age . Afterwards. high angle ducti le shear zones developed, with 10N20 direction, sinistral movement. and recrystallizat ion under green schist facies conditions. This event seems to be of Early Proterozoic age and introduced modifications o n the ear lier structural geometry. An ensialic basin could be developed and clo sed in some interval of the, 1.850-4 50 Ma period; its sedimentary fillin g, the Natividad e Group, accumulated on stable shelf environme nt. was folded with ON20 trending axis and slightly transformed by low grade metamorphism. T ranscurrent SON60 dextral and 3OON3 15 sinistra l faults also could form, cutting this supracrus tal sequence and the older Goiano Com plex.
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Resumo No extremo noroeste da Província Borborema foi identifi cado um maciço alcalino subsaturado, o Nefelina Sienito Brejinho (NSB), alojado em gnaisses do Paleoproterozoico do Complexo Granja. As investigações envolveram mapeamento de detalhe do corpo, acompanhado de análises petrográfi cas e geocronológicas, que permitiram reconstruir a sua história evolutiva. Foram identifi cadas cinco fácies petrográfi cas, com a sua distribuição cartográfi ca, associações mineralógicas presentes e análises texturais/estruturais sugerindo a atuação de processos de cristalização fracionada, com forte controle da ação da gravidade e imiscibilidade de líquidos na história da cristalização magmática do maciço. Os estudos geocronológicos realizados pelo método Rb-Sr em rocha total revelaram valor de 554 ± 11 Ma, interpretado como a idade mínima para cristalização e emplacement do NSB, no fi nal do Neoproterozoico. No contexto tectônico, esse magmatismo alcalino pode ser relacionado ao evento extensional responsável pela implantação do Gráben Jaibaras e seus correlatos no oeste do Ceará, assim como à granitogênese da região, cujas idades situam-se no intervalo entre 530 e 590 Ma. Situação semelhante é reconhecida na borda norte da Bacia do Amazonas, com o Complexo Alcalino-Ultramáfi co-Carbonatítico Maicuru (589 Ma) alojado no embasamento gnáissico paleoproterozoico do Cráton Amazônico. A situação geológica e temporal do NSB permite situá-lo posteriormente à tectônica transcorrente representada na área pela Zona de Cisalhamento Santa Rosa, uma ramifi cação do Lineamento Transbrasiliano, e anterior à Bacia do Parnaíba. Disso resulta que esse magmatismo alcalino pode ser interpretado como um importante registro da fase rifte que prenunciou a instalação dessa bacia no início do Paleozoico. A sua caracterização, até então sem similar na Província Borborema, abre novas perspectivas de pesquisa em todo o embasamento da Bacia do Parnaíba, tendo em vista a importância tectônica e metalogenética desse tipo de magmatismo.Palavras-chave: Nefelina Sienito Brejinho, magmatismo alcalino, geocronologia Rb-Sr, Província Borborema. Abstract Petrography, geochronology and tectonic signifi cance of Brejinho Nepheline Syenite: NW BorboremaProvince. In the extreme northwest of the Borborema Province was identifi ed an alkaline massif named Brejinho Nepheline Syenite, emplaced in Paleoproterozoic gneisses of the Granja Complex. The investigation involved the mapping, detailed petrographic analyses and Rb-Sr geochronology, allowing to the reconstruction of the evolutionary history of this pluton in the tectonic context of the Borborema Province. Five petrographic facies have been mapped and the mineralogical and textural/structural analyses performance suggest the processes of fractional crystallization, with strong control of gravitational action and liquid immiscibility in the history of magmatic crystallization of the massif. The age of 554 ± 11 Ma was obtained by Rb-Sr wholerock geochronology and was interpreted as the minimum age for crystallizat...
ResumoA partir de algumas características essenciais da chamada economia do compartilhamento, o artigo busca traçar algumas considerações jurídicas sobre o seu desenvolvimento, buscando na principiologia constitucional e contatual elementos que reforçam aspectos positivos desse fenômeno. Destaque é dado ao princípio da função social dos bens, e em especial àquela relativa aos bens móveis, e ao princípio da boa-fé objetiva, enfatizando como iniciativas típicas da economia do compartilhamento podem incrementar a transparência e a confianças nas relações contratuais, além de gerar impactos relevantes sobre a forma de realização das mais diversas atividades nas cidades.Palavras-Chave: Economia do Compartilhamento; Função Social; Boa-fé objetiva; Tutela da Confiança; Direito Civil; Direito da Cidade. AbstractThis article aims to analyze a set of legal features concerning the evolution of the so-called sharing economies. In order to better understand how Law can interplay with the expansion of activities usually labeled as part of the sharing economies movement, the article suggests that the constitutional principle of social function of property as well as the strengthening of the principle of objective good faith could serve as two relevant guides to such an analysis. The compliance requirements stated in some constitutional and other legal provisions concerning the social function of property can lead to a better way to examine the impact of sharing economies activities in the cities. On other hand, the principle of objective good faith can emphasize how typical sharing economy initiatives might increase transparency and trusts in contractual relationships.
This chapter offers a critical analysis of Brazilian copyright law and legal scholarship, through the particular lens of exceptions and limitations.Copyright exceptions and limitations are those positive rights granted to users of cultural materials, to be exercised without prior authorization of copyright holders. 1 Exceptions and limitations are widely recognized as an essential part of the balance between public and private interests inherent in copyright law, deeply linked to the underlying rationales for copyright itself. This is an essential starting point; however, two additional perspectives also merit emphasis.First, copyright exceptions and limitations are a particularly important strategy for addressing the challenges and opportunities posed by new information and communication technology. These include the challenges that the Internet and digital reproduction technologies pose to traditional copyright-based business models, as well as the opportunities these technologies offer to move from a society of information consumers to a society of information users -a transition that is already under way (BenklerWe make no distinction between exceptions and limitations, but use the two terms interchangeably.A distinction can certainly be made, however, with limitations referring to works falling entirely outside the scope of copyright protection, and exceptions referring to permitted uses of works that are protected by copyright (Ricketson 2003).
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