Contexto geológico e estrutural do Maciço Rio Apa, sul do Cráton amazônico - MS

Rio Apa Massif crops out in the Mato Grosso do Sul state and corresponds to the southeastern portion of the Amazonian Craton dominantly Paleoproterozoic in age. Rio Apa Complex is oldest and it is composed mainly by migmatitic orthogneisses, beyond amphybolites, tonalities and granodiorite. Alto Tererê Group is composed by schists, biotitemuscovite gneisses and micaceous quartzites generally rich in garnets, beyond metabasic rocks of low amphibolite facies. The Amoguijá Group is constituted by Alumiador Intrusive Suite, which is represented by a sieno to monzogranitic batholith and Serra da Bocaina Volcanic Suite composed of volcanoclastic rocks of alkali riolites to monzoriolites compositions and pyroclastic products. Overlaying towards East and South occurs Neoproterozoic metasedimentary rocks from the Paraguai Folded Belt (Cuiabá, Corumbá and Jacadigo Groups - Urucum Formation). Structural-metamorphic framewok is identified by five deformational phases but the actual tectonic and metamorphic structure shows the superposed tectonic array of the Paraguai Folded Belt. Rocks from Rio Apa Complex, Alto Tererê Group and Amoguijá Group record an older structural evolution defined by (Dn-1 and Dn). The deformational phases (Dn+1 and Dn+2) are visible mainly in rocks of Paraguai Folded Belt beyond the last deformation (Dn+3) that imprints all sequences.

Suíte vulcânica serra da bocaina, grupo amoguijá, maciço rio apa-MS

The Rio Apa Massif corresponds to the southeastern portion of the Amazonian Craton and crops out in the Mato Grosso do Sul State, Brazil. It is constituted by rocks of paleoproterozoic age of Rio Apa Complex, Alto Tererê Group and the plutonic-volcanic suites of the Amoguijá Group, subdivided in Alumiador Intrusive suits and Serra da Bocaina Volcanic. The Volcanic Suite is represented by São Francisco and Bocaina mountains and is constituted by terms of the composition of alkali - rhyolitic to rhyolitic, including in minor amounts riodacite, andesite and dacite. It consists of a variety of textual subvolcanic rocks, volcanic and varied volcanoclastics. The pyroclastic deposits are very expressive and consist of pyroclastic particle immerse in aphanitic matrix, fine grained or amorphous, where quartz, feldspar, chlorite, sericite, microlithes of carbonate, sparse spherulites and reliquiar volcanic glass can be distinguished. The pyroclastic rocks are represented by breccias, ignimbrites, agglomerate, tuffs, lapillistones and pumices and contain commonly vitroclasts, lithoclasts and crystalloclasts, pumices, fiammes, glass shards, spherulites, vesicles and amygdales. They are calc-alkaline rocks with dominant peraluminous character high to middle potassium series and define a sin-colisional dominant tectonic and are genetically associated to the evolution of the Amoguijá Magmatic Arc.

Suíte plutônica Alumiador, grupo Amonguijá, maciço rio apa - MS

The Rio Apa Massif corresponds the southern portion of the Amazon Craton and is located in the southwest of Mato Grosso do Sul State. It consists on Paleoproterozoic rocks of Rio Apa Complex, Alto Tererê Group and Amonguijá Group, is subdivided into Alumiador Plutonic Suite and Serra da Bocaina Volcanic Suite. The volcanic suite is comprises sub volcanic, volcanic and varied volcanoclastics rocks with composition ranging from alkali-rhyolitic to rhyolite types. The plutonic suite corresponds to an N-S elongated batholith and is characterized by four main segments delimited by NW-SE faults. The southern and central main segments, discussed in this paper, are characterized by the following petrographic facies: medium to fine grained hornblende-biotite monzogranites, coarse grained biotite monzogranites, graphic biotite sienogranites and muscovite sienogranites and the northern segment is contemporaneous and is composed of two different sequences of rocks, one acid and another of basic to ultrabasic composition. The southern and central segment consists of to chemically compatible rocks with the types I and A Granites. These are calc-alkaline rocks of high potassium to the shoshonitic and subalkaline. Constitute sin-collisional granites of metaluminous the peraluminous characters of the Amonguijá Magmatic Arc, but they exhibit late litotypes with chemical characteristics of post tectonic granites from intraplate environment.

Evolução do Terreno rio Apa e sua relação com a faixa de dobramentos Paraguai

Pós-graduação em Geologia Regional - IGCE

SUÍTE VULCÂNICA SERRA DA BOCAINA, GRUPO AMOGUIJÁ, MACIÇO RIO APA - MS

O Maciço do Rio Apa corresponde à porção meridional do Cráton Amazônico no sudoeste do estado de Mato Grosso do Sul e é constituído pelas rochas de idade paleoproterozóicas do Complexo Rio Apa, Grupo Alto Tererê e suítes plutono - vulcânica ácida do Grupo Amoguijá, dividido em suítes Intrusiva Alumiador e Vulcânica Serra da Bocaina. A suíte vulcânica é caracterizada nas serras de São Francisco e Bocaina, constituída dominantemente por termos de composição álcali - riólitos a riólitos, incluindo em menores proporções riodacitos, andesitos e dacitos. É constituída por uma diversidade textural de rochas subvulcânicas, vulcânicas e variedades vulcanoclásticas. Os depósitos piroclásticos de maior expressão são constituídos por partículas piroclásticas imersas em matriz afanítica de granulometria fina ou amorfa, onde se pode distinguir quartzo, feldspato, clorita, sericita, micrólitos de carbonato, esferulitos esparsos e vidro vulcânico reliquiar. As rochas piroclásticas são representadas por brechas, tufos, ignimbritos, aglomerados, lapilitos e púmices, contendo geralmente vitroclastos, litoclastos e cristaloclastos, púmices, fiammes, glass shards, esferulitos, vesículas e amígdalas. São rochas cálcio - alcalinas pertencentes à série de alto potássio de caráter predominantemente peraluminoso e definem magmatismo sincolisional e encontram - se geneticamente associadas à evolução do Arco Magmático Amoguijá. Palavras-chave: Maciço Rio Apa, Suíte Vulcânica Serra da Bocaina, litogeoquímica, petrografia.

Isotopic evidence for the late Brasiliano (500-550 Ma) ore-forming mineralization of the Araes gold deposit, Brazil

The Araes gold deposit, located in eastern Mato Grosso State, central Brazil, is hosted in Neoproterozoic volcanosedimentary rocks of the Paraguay belt, which formed during collision of the Amazonian craton and the Rio Apa block. Ar-40/Ar-39 geochronology and Pb and S isotopic analyses constrain the timing and sources of mineralization. Three biotite flakes from two samples of metavolcanic host rock yield Ar-40/Ar-39 plateau ages between 5941 and 531 Ma, interpreted as cooling ages following regional metamorphism. Clay minerals from a hydrothermal alteration zone yield an Ar-40/Ar-39 integrated age of 503 +/- 3 Ma. Galena grains from ore-bearing veins yield values of Pb-206/(204)pb from 17.952 to 18.383, Pb-207/Pb-204 from 15.156 to 15.811, and Pb-208/Pb-204 from 38.072 to 39.681. Pyrite grains from ore-bearing veins yield values of Pb-206/Pb-204 from 18.037 to 18.202, Pb-207/Pb-204 from 15.744 to 15.901., and Pb-208/(204)pb from 38.338 to 38.800. Pb isotope variations may be explained in terms of mixing a less radiogenic lead component (mu similar to 8.4) from mafic and ultramafic basement host-rocks (Nova Xavantina metavolcanosedimentary rocks) and a more radiogenic lead component (mu similar to 9.2) probably derived from supracrustal rocks (Cuiaba sedimentary groups). Sulfur isotope compositions are homogeneous, with delta S-34 values ranging from -1.1 parts per thousand to 0.9 parts per thousand (galena) and -0.7 parts per thousand to 0.9 parts per thousand (pyrite), suggesting a mantle-derived reservoir for the mineralizing solutions. Based on the Ar, Pb, and S isotope data, we suggest that the precious metals were remobilized from metavolcanic host rocks by hydrothermal solutions during Brasilide-Panafrican regional metamorphism. The Arabs gold deposit probably formed during a late stage of the orogeny, coeval with other mineralization events in the Paraguay Belt.

U Pb and Sm Nd geochronologic studies of the eastern Borborema Province, Northeastern Brazil: initial conclusions

The Borborema Province of NE Brasil comprises the central part of a wide Pan-African-Brasiliano orogenetic belt that formed as a consequence of late Neoproterozoic convergence and collision of the São Luis-West Africa craton and the São Francisco-Congo-Kasai cratons. New Sm Nd and U Pb results from the eastern part of this province help to define the basic internal architecture and pre-collisional history of this province, with particular emphasis on delineating older cratonic terranes, their fragmentation during the Mesoproterozoic, and their assembly into West Gondwana during the Pan African-Brasiliano orogeny at ca. 600 Ma. The region can be divided into three major geotectonic domains: a) Rio Piranhas-Caldas Brandão massif, with overlying Paleoproterozoic to Neoproterozoic supracrustal rocks, north of the Patos Lineament; b) the Archean to Paleoproterozoic São Francisco craton (SFC) to the south; and c) a complex domain of Paleoproterozoic to Archean basement blocks with several intervening Mesoproterozoic to Neoproterozoic fold belts in the center (south of Patos Lineament and north of SFC). The northern and central domains comprise the Borborema Province. Archean basement gneiss and Transamazonian granulite of northern SFC are exposed in the southern part of the central domain, underlying southern parts of the Sergipano fold belt. Basement in the Rio Piranhas massif appears to consist mostly of Transamazonian (2.1 to 2.2 Ga) gneissic rocks; Nd model ages (TDM) of ca. 2.6 Ga for 2.15 Ga gneisses indicate a substantial Archean component in the protoliths to these gneisses. The Caldas Brandão massif to the east yields both Transamazonian and Archean U Pb zircon and Nd (TDM) ages, indicating a complex architecture. Metasedimentary rocks of the Jucurutu Formation yield detrital zircons with original crystallization ages as young as 1.8 Ga, indicating that these rocks may be late Paleoproterozoic and correlate with other ca. 1.8 Ga cratonic supracrustal rocks in Brazil such as the Roraima Group and Espinhaço Group. Most metavolcanic and pre-Brasiliano granitic units of the Sergipano (SDS), Pajeú-Paraíba (SPP), Riacho Pontal (SRP), and Piancó-Alto Brígida (SPAB) fold belts in the central domain formed ~ 1.0 ± 0.1 Ga, based on U Pb ages of zircons. Nd model ages (TDM) for these same rocks, as well as Brasiliano granites intruded into them and large parts of the Pernambuco-Alagoas massif, are commonly 1.3-1.7 Ga, indicating that rocks of the fold belts were not wholly derived from either older (> 2.1 Ga) or juvenile (ca. 1.0 Ga) crust, but include mixtures of both components. A simple interpretation of Brasiliano granite genesis and the Nd data implies that there is no Transamazonian or Archean basement underlying large parts of these fold belts or of the Pernambuco-Alagoas massif. An exception is a belt of syenitic Brasiliano plutons (Syenitoid Line) and host gneisses between SPAB and SPP that clearly has a Transamazonian (or older) source. In addition, there are several smaller blocks of Archean to Transamazonian gneiss that can be defined within and among these fold belts. These blocks do not appear to constitute a continuous basement complex, but appear to be isolated older crustal fragments. Our data support a model in which ca. 1.0 Ga rifting was an important tectonic and crust-forming event along the northern edge of the São Francisco craton. Our data also show that significant parts of the Borborema Province are not remobilized Transamazonian to Archean crust, but that Mesoproterozoic crust is a major feature of the Province. There are several small remnants of older crust within the area dominated by Mesoproterozoic crust, suggesting that the rifting event created several small continental fragments that were later incorporated into the Brasiliano collisional orogen. We cannot at present determine if the Rio Piranhas-Caldas Brandão massifs and the older crustal blocks of the central domain were originally part of the São Francisco craton or whether some (or all) of them came from more exotic parts of the Proterozoic Earth. Finally, our data have not yet revealed any juvenile terranes of either Transamazonian or Brasiliano age. © 1995.

Os granitóides brasilianos da faixa de dobramentos paraguai, MS e MT

The Brazilian Granitic Province from southeastern Mato Grosso do Sul and Mato Grosso region, central western Brazil, can be divided into two major groups and/or magmatic events related to the evolution of the Paraguay Fold Belt. The southern portion crops out in Mato Grosso do Sul State and is constituted by the Taboco, Rio Negro, Coxim and Sonora massifs forming NE-SW oriented, elongated small intrusions. The north portion crops out in Mato Grosso State and is constituted by the São Vicente, Araguaiana and Lajinha batholiths. Lithogeochemical aspects of the northern granites point to Type-I granites ranging from K calc-alkaline to high-K, peraluminous to metaluminous in composition, generated in an environment of continental collision and/or post- collision decompression. The southern granites are Type-I, from K calc-alkaline to high-K, peraluminous to subordinate metalummous, in a syn-collision continental arc environment with the exception of some pre-collisional facies from the Rio Negro Massif. The southern granites have less SiO 2 and K 2O, and are less differentiated and evolved than granites from the northern region. The four southern granites can be grouped into two subordinate sets with the degree of differentiation increasing from South (Taboco and Rio Negro) to North (Coxim and Sonora). The granitic rocks are characterized by a magmatism generated by melting of material from the lower crust which suggests that in this province the formation from non-cogenetic magmas with diversified compositions and distinct degrees of fractioning reaching more steady consolidated environments at the end of the collisional event in the southeastern Amazonian Craton.

The puzzle assembled: Ediacaran guide fossil Cloudina reveals an old proto-Gondwana seaway

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

As mudanças climáticas e suas consequências observadas na Região Metropolitana de São Paulo e a importância da APA Várzea do Rio Tietê na minimização de danos

O maior rio do Estado de São Paulo, o Rio Tietê, teve, na Região Metropolitana de São Paulo, suas áreas de várzeas tomadas pelo processo de urbanização e metropolização da população. Parte de suas terras inundáveis passou por processos de aterramento e impermeabilização para que a instalação de indústrias e infraestruturas fosse possível. A APA da Várzea do Rio Tietê foi criada para controlar o processo de ocupação do entorno do rio e na tentativa de amortecer as enchentes causadas por tempestades, cada vez mais constantes. Essas chuvas torrenciais são causadas pela influência das Ilhas de Calor da RMSP com o encontro de brisas marítimas, e causam inundações e destruições

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)

Revisitação de Bromeliaceae na APA Santuário ecológico da Pedra Branca Caldas, MG

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo da vulnerabilidade à erosão com a aplicação da Equação Universal de Perda de Solo na alta bacia hidrográfica do rio Jacaré Pepira, utilizando SIG/SPRING

Pós-graduação em Geociências e Meio Ambiente - IGCE

Zoneamento ambietal da APA Corumbataí (SP) de acordo com critérios de vulnerabilidade ambiental

Pós-graduação em Geociências e Meio Ambiente - IGCE

Análise socioeconômica e ambiental das populações tradicionais da Reserva de Desenvolvimento Sustentável (RDS) dos Quilombos de Barra do Turvo e Área de Proteção Ambiental (APA) do Planalto do Turvo, Mosaico de Jacupiranga/SP

As Unidades de Conservação são sub-divididas em duas categorias: Proteção Integral, com objetivos de manutenção do ecossistema livre da interferência humana na qual é permitido apenas o uso indireto; e de Desenvolvimento Sustentável, que tem por objetivo equilibrar a conservação da natureza com o uso sustentável dos recursos naturais. O Parque de Jacupiranga era localizado na região sul do estado de São Paulo, denominada Vale do Ribeira, sendo criado em 1961 com aproximadamente 141 mil ha e cerca de 8 mil moradores presentes no seu interior, incluindo comunidades tradicionais, quilombolas, e agricultores migrantes de outros estados. O mosaico de Jacupiranga foi criado em 2008, com o objetivo de atender reivindicações dos moradores que sofriam restrições de suas atividades por estar dentro de uma unidade de conservação de proteção integral, com isso, o antigo PEJ sofreu a recategorização, e foram criadas 3 unidades de proteção integral e 7 de uso sustentável na antiga área do parque. O objetivo foi analisar as mudanças socioeconômicas e ambientais das famílias que sofreram com a recategorização do antigo Parque Estadual do Jacupiranga para a Reserva de Desenvolvimento Sustentável (RDS) dos Quilombos de Barra do Turvo e a Área de Proteção Ambiental (APA) do Planalto do Turvo, Mosaico de Jacupiranga/SP, onde a legislação ambiental permite a presença de moradores bem como suas atividades de subsistência. A coleta de dados foi feita pelo processo de entrevistas estruturadas realizadas com 12 moradores escolhidos por indicação dos próprios moradores das áreas tanto da APA quando da RDS. Com isso, pode-se observar uma maior liberdade nas atividades de uso da terra praticadas pelos moradores, contudo, mesmo com a recategorização, os investimentos públicos locais não são suficientes para propiciar uma boa qualidade de vida para as famílias das áreas analisadas