The Serido Group of NE Brazil, a late Neoproterozoic pre- to syn-collisional basin in West Gondwana: insights from SHRIMP U-Pb detrital zircon ages and Sm-Nd crustal residence (T-DM) ages

The Serido Group is a deformed and metamorphosed metasedimentary sequence that overlies early Paleoproterozoic to Archean basement of the Rio Grande do Norte domain in the Borborema Province of NE Brazil. The age of the Serido Group has been disputed over the past two decades, with preferred sedimentation ages being either Paleoproterozoic or Neoproterozoic. Most samples of the Serido Formation, the upper part of the Serido Group, have Sm-Nd T-DM ages between 1200 and 1600 Ma. Most samples of the Jucurutu Formation, the lower part of the Serido Group, have T-DM ages ranging from 1500 to 1600 Ma; some basal units have T-DM ages as old as 2600 Ma, reflecting proximal basement. Thus, based on Sm-Nd data, most, if not all, of the Serido Group was deposited after 1600 Ma and upper parts must be younger than 1200 Ma.Cathodoluminescence photos of detrital zircons show very small to no overgrowths produced during ca. 600 Ma Brasiliano deformation and metamorphism, so that SHRIMP and isotope dilution U-Pb ages must represent crystallization ages of the detrital zircons. Zircons from meta-arkose near the base of the Jucurutu Formation yield two groups of ages: ca. 2200 Ma and ca. 1800 Ma. In contrast, zircons from a metasedimentary gneiss higher in the Jucurutu Formation yield much younger ages, with clusters at ca. 1000 Ma and ca. 650 Ma. Zircons from metasedimentary and metatuffaceous units in the Serido Formation also yield ages primarily between 1000 and 650 Ma, with clusters at 950-1000, 800, 750, and 650 Ma. Thus, most, if not all, of the Serido Group must be younger than 650 Ma. Because these units were deformed and metamorphosed in the ca. 600 Ma Brasiliano fold belt during assembly of West Gondwana, deposition probably occurred ca. 610-650 Ma, soon after crystallization of the youngest population of zircons and before or during the onset of Brasiliano deformation.The Serido Group was deposited upon Paleoproterozoic basement in a basin receiving detritus from a variety of sources. The Jucurutu Formation includes some basal volcanic rocks and initially received detritus from proximal 2.2-2.0 Ga (Transamazonian) to late Paleoproterozoic (1.8-1.7 Ga) basement. Provenance for the upper Jucurutu Formation and all of the Serido Formation was dominated by more distal and younger sources ranging in age from 1000 to 650 Ma. We suggest that the Serido basin may have developed as the result of late Neoproterozoic extension of a pre-existing continental basement, with formation of small marine basins that were largely floored by cratonic basement (subjacent oceanic crust has not yet been found). Immature sediment was initially derived from surrounding land; as the basin evolved much of the detritus probably came from highlands to the south (present coordinates). Alternatively, if the Patos shear zone is a major terrane boundary, the basin may have formed as an early collisional foredeep associated with south-dipping subduction. In any case, within 30 million years the region was compressed, deformed, and metamorphosed during final assembly of West Gondwana and formation of the Brasiliano-Pan African fold belts. (C) 2003 Elsevier B.V. All rights reserved.

Fission track and U-Pb in situ dating applied to detrital zircon from the Vale do Rio do Peixe Formation, Bauru Group, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

From Amazonia to the Atlantic forest: Molecular phylogeny of Phyzelaphryninae frogs reveals unexpected diversity and a striking biogeographic pattern emphasizing conservation challenges

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Collectives of humans-with-media in mathematics education: Notebooks, blackboards, calculators, computers and ... notebooks throughout 100 years of ICMI

The main aim of this study was to present evidence of the ways in which different media have conditioned and dramatically reorganized education, in general, and mathematics education, in particular. After an introduction of the theme, we discuss the epistemological perspective that provides the foundation for our analysis: the notion of humans-with-media. Then, we briefly illustrate how the medium is related to the scientific production of mathematical knowledge. We take a detour into the world of art to examine how devices and instruments have historically been associated with the production of mathematical knowledge. Then, we review studies on the history of education to show how traditional media were introduced into schools and have influenced education. In particular, we examine how devices such as blackboards and notebooks, which were novelties a 100 years ago, came to be accepted in schools and the mathematical activities that were promoted with their use. Finally, we discuss how information technology has changed education and how the Internet may have an impact on mathematics education comparable to that of the notebook over a century ago. © FIZ Karlsruhe 2009.

Programa pró-letramento matemática: uma abordagem de grandezas e medidas com inserção dos temas transversais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Trabalhando conceitos matemáticos com tecnologias informáticas por meio da elaboração de projetos de construção civil

Pós-graduação em Educação Matemática - IGCE

A prática do professor de matemática em classes de recuperação de ciclo II no regime de progressão continuada do estado de São Paulo

Pós-graduação em Educação Matemática - IGCE

O cálculo e a invenção na poética de Stockhausen

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Theodoro Augusto Ramos: um estudo comentado de sua tese de doutoramento

Pós-graduação em Educação Matemática - IGCE

As contribuições de Chaim Samuel Hönig para o desenvolvimento da matemática brasileira

Pós-graduação em Educação Matemática - IGCE

Notas de testemunho e recalque: uma experiência musical dos traumas sociais brasileiros em Chico Buarque e Paulinho da Viola (de meados da década de 1960 a meados da década de 1970)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Narrativas de professoras que ensinam matemática na região de Blumenau (SC): sobre as feiras catarinenses de matemática e as práticas e e concepções sobre ensino e aprendizagem de matemática

Pós-graduação em Educação para a Ciência - FC

O longo caminho: guerreiro ramos e a sociologia da administração antes de a nova ciência das organizações

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Solution to bilharmonic equation with vanishing potential

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Matemática comercial e financeira com a utilização de recursos digitais: uma experiência no ensino médio

This work aimed to investigate the possible contributions of the use of digital resources in the teaching and learning process of Commercial and Financial Mathematics concepts to high school students. Its development has included a survey of some researches on the topic as well as an experimental study of a qualitative type, in which the Webquest was used as methodology. It uses the computer, more precisely the internet resources, to assist students in building up knowledge. Eight meetings were held, in the after-school period, with a group of students of the second year of high school at a state public school in the city of Guaratinguetá. Aiming to evaluate the knowledge that students had about the theme, it was applied a diagnosis at first glance for further analysis and development of activities and interventions according to the students’ answers. Once the research data was analyzed, it was noted that the students had little knowledge regarding the basic contents of Commercial and Financial Mathematics, in addition to presenting difficulties in handling some of the digital resources used in the meetings. Nonetheless, from the students’ works, it was seen significant advances in understanding and building up knowledge on concepts such as percentage, simple and compound interest, savings, and sales involving prompt payment or in arrears