Nova proposta de arcabouço estratigráfico e evolução tectono-sedimentar do registro cretácico da Bacia dos Parecis, centro oeste do Brasil

A Bacia dos Parecis é uma bacia intracratônica, com uma área de 500.000 km2 na região Centro-Oeste do Brasil. Ocupa a porção sul-sudeste do Cráton Amazônico, tendo este como maior parte de seu embasamento. Acumula mais de 6.000 m de sedimentos, relacionados ao Paleozoico, Mesozoico e Cenozoico. O registro mesozoico inclui unidades sedimentares e vulcânicas. O registro cretácico da Bacia dos Parecis consiste em duas sequências sedimentares com assinaturas deposicionais distintas. Essas sequências são fisicamente descontínuas e relacionadas a diferentes depocentros, nas porções leste e oeste do Arco da Serra Formosa, ou seja, sub-bacias Juruena e Alto Xingu. Isto gera controvérsias em termos de correlação regional, posicionamento estratigráfico e correta subdivisão das sequências. Com base em afloramentos e testemunhos de sondagem foi possível a reconstituição do registro a partir das associações de fácies. Estas associações juntamente com o reconhecimento regional de superfícies e relações estratigráficas permitiu a identificação de uma assinatura deposicional diferencial para cada sequência. Na sub-bacia Juruena foram depositadas sequências predominantemente clásticas, fluviais e eólicas. Na sub-bacia do Alto Xingu, na base foram identificadas fácies de natureza química e clástica e no topo, sedimentação clástica. A reconstituição da evolução da bacia no Mesozoico e a contextualização das unidades cretácicas foram efetuadas levando-se em conta os registros do tectonismo, do magmatismo e da sedimentação na região. A evolução da bacia no Mesozoico teve início no Triássico Superior e Jurássico Inferior com vulcanismo e sedimentação, sucedido de soerguimento e erosão até o Cretáceo Inferior, quando ocorreram magmatismos básico e alcalino. A partir do Cretáceo Superior, com início da fase compressiva da Orogenia Andina e abertura do Oceano Atlântico, desenvolveu-se tectonismo e a sedimentação na sub-bacia Juruena no Cenomaniano. Porém, na sub-bacia Alto Xingu esta ocorre a partir do Coniaciano. A análise do registro fossilífero e as relações com unidades adjacentes indicam uma idade entre Cenomaniano-Turoniano para a sequência da sub-bacia Juruena e Coniaciano-Santoniano para a sequência da sub-bacia Alto Xingu. Assim, foi proposta uma nova unidade litoestratigráfica para esta última, denominada de Formação Rio Tapirapé. A atuação da tectônica na geração de subsidência diferenciada para cada sub-bacia ocasionou a geração de diferentes assinaturas deposicionais. Na sub-bacia Juruena a taxa de sedimentação superior à taxa de subsidência é perceptível, gerando sequências clásticas de alta energia. Na sub-bacia Alto Xingu, a taxa de subsidência é superior à taxa de sedimentação, com um sistema lacustre transgressivo nas fases iniciais. Ao final em ambas as sub-bacias prevalecem sistemas sedimentares fluviais e deltaicos enquanto a taxa de subsidência é reduzida. A reconstituição paleoambiental da sequência cretácica da sub-bacia Alto Xingu identificou uma sedimentação clasto-química de fundo e borda de lago na base. Na porção superior ocorre uma progradação com ambientes de prodelta, frente deltaica e uma planície deltaica com planície fluvial e deposição eólica. O posicionamento cronoestratigráfico Coniaciano-Santoniano baseou-se em fósseis de vertebrados e ostracodes que tem crono-correlatos regionais na Formação Adamantina (Grupo Bauru) e Formação Capacete (Bacia Sanfranciscana) e ainda na Formação Bajo de Carpa (Grupo Neuquén, na Argentina).The Parecis Basin is an intracratonic basin, covering a huge area of 500.000 km2 in center-west portion of Brazil. The Amazonian Craton constitutes the most part of its basement. In this basin, there are an accumulation of more than 6,000 m of sediments, related to Paleozoic, Mesozoic and Cenozoic ages. The Mesozoic record includes sedimentary and volcanic units. The cretaceous record of the Parecis Basin is represented by two sedimentary sequences characterized by distinct depositional signatures. These sequences are physically discontinuous, and related to different depocenters located in the east and west of Serra Formosa Arch, namely Juruena and Alto Xingu sub-basins. So, this distribution is controversy in terms of regional correlation, stratigraphic positioning and correct subdivision of the sequences. Based on outcrops and cores information it was possible the reconstruction of the record from the facies association, which together with regional surface recognition and stratigraphic relations allowed the identification of a differential depositional signature for each sequence. In the Juruena sub-basin, predominantly clastic fluvial and aeolian sequences were deposited. In the Alto Xingu sub-basin the base is marked by facies of lacustrine chemical and clastic nature but top, clastic sedimentation of a fluvio-deltaic system is recognized. The reconstruction of the mesozoic evolution of the basin and contextualization of the Cretaceous units were carried out taking into account records of tectonism, magmatism and sedimentation in the region. The basin evolution in Mesozoic age start in Upper Triassic to Lower Jurassic period where occurred volcanism and sedimentation, followed by uplift and erosion until the Lower Cretaceous, when as occurred basic and alkaline magmatism. From the Upper Cretaceous, with the beginning of the compressive phase of Andean Orogeny and opening of the Atlantic Ocean, tectonism and sedimentation were developed in Juruena Sub-basin in the Cenomanian and Alto Xingu Sub-basin from Coniacian. The relation of the fossiliferous record with adjacent units allows to assign one related age between Cenomanian-Turonian to Juruena sub-basin sequence. But the Coniacian-Santonian to Alto Xingu sub-basin is being proposed an new lithostratigraphic. unit named Rio Tapirapé Formation results from this recognition. The tectonism is the main event in the generation of differentiated subsidence to each sub-basin and the differential depositional signatures. In the Juruena sub-basin the sedimentation rate over the subsidence rate is perceptible, and a clastic high energy sequence is deposited. In the Alto Xingu sub-basin, the subsidence rate is higher than the sedimentation rate, with a transgressive lacustrine system with chemical sedimentation in the initial phases. At the end of the process, in both sub-basins, fluvial and deltaic sedimentary systems prevail while the subsidence rate decreases. The paleoambiental reconstruction of Alto Xingu sub-basin cretaceous sequence indicates a chemical and clastic sedimentation of bottom and shoreline lake, in a context of high initial subsidence and low sedimentation rate. As the subsidence process decreased, a deltaic progradation became dominant with deposition in a prodelta environment, deltaic front and deltaic plain interbedded with fluvial plain, and aeolian deposition. The Coniacian–Santonian chronostratigraphic positioning was based on vertebrate fossils and ostracods with regional chrono-correlates in the Adamantina Formation (Bauru Group), the Capacete Formation (Sanfranciscana Basin), and also in the Bajo de la Carpa Formation (Neuquén Group, in Argentina)

Estratigrafia do Batólito Florianópolis, Cinturão Dom Feliciano, na Região de Garopaba-Paulo Lopes, SC

In southern Brazil, the Florianopolis Batholith results from prolonged, mainly granitic magmatism, as part of the Neoproterozoic Dom Feliciano Belt. Plutonic associations in this belt are related to transpressive tectonism (650-580 Ma) in post-collisional setting, where the translithospheric discontinuities of the Southern Brazilian Shear Belt have triggered magmatism, acting as channels for melts originated in deep crustal or mantle sources. In the region of Garopaba-Paulo Lopes, a fraction of this magmatism was studied, resulting in a formal proposition for its stratigraphic organization in igneous suites. A small volume of gneissic host rocks is found as roof pendants. The Paulo Lopes Suite comprises the foliated Paulo Lopes Granite, Garopaba Granitoids and Silveira Gabbro. It is characterized as porphyritic granitoids of high-K tholeiitic affinity, coeval with mafic, tholeiitic magmatism. It is followed by metaluminous, alkaline series granitoids of the Pedras Grandes Suite, namely the Vila da Penha Granite, comprising heterogranular and porphyritic facies, and the Serra do Tabuleiro Granite, comprising heterogranular, equigranular and porphyritic facies. The Cambirela Suite, last magmatic episode in the study area, encompasses alkaline plutonic, volcanic and subvolcanic rock types, as the Ilha Granite, the Cambirela Rhyolite and the Itacorumbi Granite. Hypabissal rocks are also part of this suite, and result from recurrent acid and basic magma pulses emplaced either as idividual dykes or composite ones. The magmatic associations described in this region attest to magma emplacement under a moderate to low stress field, possibly extinguished by the time the Cambirela Suite crystallized. Their age values indicate that they are mostly contemporaneous to the post-collisional, syntectonic magmatism of the Southern Brazilian Shear Belt, and the preservation of magmatic structures such as modal layering, relatively uncomon in granitoids, may also be attributed to their emplacement far from the main deformation sites. Features indicative of coeval mafic and felsic magmas are described in all three magmatic associations, and are especially significant in the Paulo Lopes and Cambirela suites. They attest to continuous mantle participation in the batholith construction.In southern Brazil, the Florianopolis Batholith results from prolonged, mainly granitic magmatism, as part of the Neoproterozoic Dom Feliciano Belt. Plutonic associations in this belt are related to transpressive tectonism (650-580 Ma) in post-collisional setting, where the translithospheric discontinuities of the Southern Brazilian Shear Belt have triggered magmatism, acting as channels for melts originated in deep crustal or mantle sources. In the region of Garopaba-Paulo Lopes, a fraction of this magmatism was studied, resulting in a formal proposition for its stratigraphic organization in igneous suites. A small volume of gneissic host rocks is found as roof pendants. The Paulo Lopes Suite comprises the foliated Paulo Lopes Granite, Garopaba Granitoids and Silveira Gabbro. It is characterized as porphyritic granitoids of high-K tholeiitic affinity, coeval with mafic, tholeiitic magmatism. It is followed by metaluminous, alkaline series granitoids of the Pedras Grandes Suite, namely the Vila da Penha Granite, comprising heterogranular and porphyritic facies, and the Serra do Tabuleiro Granite, comprising heterogranular, equigranular and porphyritic facies. The Cambirela Suite, last magmatic episode in the study area, encompasses alkaline plutonic, volcanic and subvolcanic rock types, as the Ilha Granite, the Cambirela Rhyolite and the Itacorumbi Granite. Hypabissal rocks are also part of this suite, and result from recurrent acid and basic magma pulses emplaced either as idividual dykes or composite ones. The magmatic associations described in this region attest to magma emplacement under a moderate to low stress field, possibly extinguished by the time the Cambirela Suite crystallized. Their age values indicate that they are mostly contemporaneous to the post-collisional, syntectonic magmatism of the Southern Brazilian Shear Belt, and the preservation of magmatic structures such as modal layering, relatively uncomon in granitoids, may also be attributed to their emplacement far from the main deformation sites. Features indicative of coeval mafic and felsic magmas are described in all three magmatic associations, and are especially significant in the Paulo Lopes and Cambirela suites. They attest to continuous mantle participation in the batholith construction

Boletín diario del Instituto Central Meteorológico: Año II Número 219 - 1894 agosto 6

A new biozone - called Ictidosaur Assemblage Zone - is proposed to the Upper Triassic Caturrita Formation from Southern Brazil, based on the discovery of a distinct tetrapod association characterized by the presence of little non-mammalian cinodonts including Riograndia guaibensis, Brasilodon quadrangularis and Brasilitherium riograndensis. Besides, the advanced procolophonid Soturnia caliodon, the dinosaur Guaibasaurus candelariensis, the dicynodont Jachaleria candelariensis, indeterminated phytosaurs and sphenodontids were also found in this association. The new biozone overlies the Rhynchosaur Assemblage Zone and encloses the “Jachaleria Level” usually cited for these layers. Stratigraphical sections, as well as facies analysis, facies associations and architectural elements confirms that the new biozone is clearly included in a distinct stratigraphical level, which reflects a marked change in the fluvial pattern of the sequence. The anastomosed/meandering pattern associated to the underlying Rhynchosaur Assemblage Zone turns to a braided to low confinement fluvial system with unconfined flows. The faunal and faciological changes may have been caused by a combined action of climatic, base level and floral changes, probably reflecting the global tendency to an increasing aridity towards the end of the Triassic. It is presumed an early Norian age for the new biozone on basis on its faunal content, on its stratigraphic placement, recovering the Carnian rhynchosaur assemblage and also on the presence of woods, leafs and reproductive structures of conifers, whose morphological pattern is exclusively Triassic

La correspondencia de Valencia : diario de noticias : eco imparcial de la opinión y de la prensa: Año XLVII Número 19325 - 1924 Mayo 27

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

Stratigraphy of the Florianópolis Batholith, Dom Feliciano Belt, in the region of Garopaba-Paulo Lopes, SC, Brazil

In southern Brazil, the Florianopolis Batholith results from prolonged, mainly granitic magmatism, as part of the Neoproterozoic Dom Feliciano Belt. Plutonic associations in this belt are related to transpressive tectonism (650-580 Ma) in post-collisional setting, where the translithospheric discontinuities of the Southern Brazilian Shear Belt have triggered magmatism, acting as channels for melts originated in deep crustal or mantle sources. In the region of Garopaba-Paulo Lopes, a fraction of this magmatism was studied, resulting in a formal proposition for its stratigraphic organization in igneous suites. A small volume of gneissic host rocks is found as roof pendants. The Paulo Lopes Suite comprises the foliated Paulo Lopes Granite, Garopaba Granitoids and Silveira Gabbro. It is characterized as porphyritic granitoids of high-K tholeiitic affinity, coeval with mafic, tholeiitic magmatism. It is followed by metaluminous, alkaline series granitoids of the Pedras Grandes Suite, namely the Vila da Penha Granite, comprising heterogranular and porphyritic facies, and the Serra do Tabuleiro Granite, comprising heterogranular, equigranular and porphyritic facies. The Cambirela Suite, last magmatic episode in the study area, encompasses alkaline plutonic, volcanic and subvolcanic rock types, as the Ilha Granite, the Cambirela Rhyolite and the Itacorumbi Granite. Hypabissal rocks are also part of this suite, and result from recurrent acid and basic magma pulses emplaced either as idividual dykes or composite ones. The magmatic associations described in this region attest to magma emplacement under a moderate to low stress field, possibly extinguished by the time the Cambirela Suite crystallized. Their age values indicate that they are mostly contemporaneous to the post-collisional, syntectonic magmatism of the Southern Brazilian Shear Belt, and the preservation of magmatic structures such as modal layering, relatively uncomon in granitoids, may also be attributed to their emplacement far from the main deformation sites. Features indicative of coeval mafic and felsic magmas are described in all three magmatic associations, and are especially significant in the Paulo Lopes and Cambirela suites. They attest to continuous mantle participation in the batholith construction.In southern Brazil, the Florianopolis Batholith results from prolonged, mainly granitic magmatism, as part of the Neoproterozoic Dom Feliciano Belt. Plutonic associations in this belt are related to transpressive tectonism (650-580 Ma) in post-collisional setting, where the translithospheric discontinuities of the Southern Brazilian Shear Belt have triggered magmatism, acting as channels for melts originated in deep crustal or mantle sources. In the region of Garopaba-Paulo Lopes, a fraction of this magmatism was studied, resulting in a formal proposition for its stratigraphic organization in igneous suites. A small volume of gneissic host rocks is found as roof pendants. The Paulo Lopes Suite comprises the foliated Paulo Lopes Granite, Garopaba Granitoids and Silveira Gabbro. It is characterized as porphyritic granitoids of high-K tholeiitic affinity, coeval with mafic, tholeiitic magmatism. It is followed by metaluminous, alkaline series granitoids of the Pedras Grandes Suite, namely the Vila da Penha Granite, comprising heterogranular and porphyritic facies, and the Serra do Tabuleiro Granite, comprising heterogranular, equigranular and porphyritic facies. The Cambirela Suite, last magmatic episode in the study area, encompasses alkaline plutonic, volcanic and subvolcanic rock types, as the Ilha Granite, the Cambirela Rhyolite and the Itacorumbi Granite. Hypabissal rocks are also part of this suite, and result from recurrent acid and basic magma pulses emplaced either as idividual dykes or composite ones. The magmatic associations described in this region attest to magma emplacement under a moderate to low stress field, possibly extinguished by the time the Cambirela Suite crystallized. Their age values indicate that they are mostly contemporaneous to the post-collisional, syntectonic magmatism of the Southern Brazilian Shear Belt, and the preservation of magmatic structures such as modal layering, relatively uncomon in granitoids, may also be attributed to their emplacement far from the main deformation sites. Features indicative of coeval mafic and felsic magmas are described in all three magmatic associations, and are especially significant in the Paulo Lopes and Cambirela suites. They attest to continuous mantle participation in the batholith construction

Estratigrafia do batólito Florianópolis, cinturão Dom Feliciano, na região de Garopaba-Paulo Lopes, SC

In southern Brazil, the Florianopolis Batholith results from prolonged, mainly granitic magmatism, as part of the Neoproterozoic Dom Feliciano Belt. Plutonic associations in this belt are related to transpressive tectonism (650-580 Ma) in post-collisional setting, where the translithospheric discontinuities of the Southern Brazilian Shear Belt have triggered magmatism, acting as channels for melts originated in deep crustal or mantle sources. In the region of Garopaba-Paulo Lopes, a fraction of this magmatism was studied, resulting in a formal proposition for its stratigraphic organization in igneous suites. A small volume of gneissic host rocks is found as roof pendants. The Paulo Lopes Suite comprises the foliated Paulo Lopes Granite, Garopaba Granitoids and Silveira Gabbro. It is characterized as porphyritic granitoids of high-K tholeiitic affinity, coeval with mafic, tholeiitic magmatism.It is followed by metaluminous, alkaline series granitoids of the Pedras Grandes Suite, namely the Vila da Penha Granite, comprising heterogranular and porphyritic facies, and the Serra do Tabuleiro Granite, comprising heterogranular, equigranular and porphyritic facies. The Cambirela Suite, last magmatic episode in the study area, encompasses alkaline plutonic, volcanic and subvolcanic rock types, as the Ilha Granite, the Cambirela Rhyolite and the Itacorumbi Granite. Hypabissal rocks are also part of this suite, and result from recurrent acid and basic magma pulses emplaced either as idividual dykes or composite ones. The magmatic associations described in this region attest to magma emplacement under a moderate to low stress field, possibly extinguished by the time the Cambirela Suite crystallized. Their age values indicate that they are mostly contemporaneous to the post-collisional, syntectonic magmatism of the Southern Brazilian Shear Belt, and the preservation of magmatic structures such as modal layering, relatively uncomon in granitoids, may also be attributed to their emplacement far from the main deformation sites. Features indicative of coeval mafic and felsic magmas are described in all three magmatic associations, and are especially significant in the Paulo Lopes and Cambirela suites. They attest to continuous mantle participation in the batholith construction