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Registros recuperados: 9
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Delineating shallow Neogene deformation structures in northeastern Pará State using Ground Penetrating Radar Anais da ABC (AABC)
Rossetti,Dilce F..
The geological characterization of shallow subsurface Neogene deposits in northeastern Pará State using Ground Penetrating Radar (GPR) revealed normal and reverse faults, as well as folds, not yet well documented by field studies. The faults are identified mostly by steeply-dipping reflections that sharply cut the nearby reflections causing bed offsets, drags and rollovers. The folds are recognized by reflections that are highly undulating, configuring broad concave and convex-up features that are up to 50 m wide and 80 to 90 ns deep. These deformation structures are mostly developed within deposits of Miocene age, though some of the faults might continue into younger deposits as well. Although the studied GPR sections show several diffractions caused by...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Neogene; Northeastern Pará State; Ground Penetrating Radar; Tectonics; Sedimentary rocks.
Ano: 2003 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652003000200009
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Contribution to the stratigraphy of the onshore Paraíba Basin, Brazil Anais da ABC (AABC)
Rossetti,Dilce F.; Góes,Ana M.; Bezerra,Francisco H.R.; Valeriano,Márcio M.; Brito-Neves,Benjamim B.; Ochoa,Felipe L..
Several publications have contributed to improve the stratigraphy of the Paraíba Basin in northeastern Brazil. However, the characterization and distribution of sedimentary units in onshore areas of this basin are still incomplete, despite their significance for reconstructing the tectono-sedimentary evolution of the South American passive margin. This work provides new information to differentiate among lithologically similar strata, otherwise entirely unrelated in time. This approach included morphological, sedimentological and stratigraphic descriptions based on surface and sub-surface data integrated with remote sensing, optically stimulated luminescence dating, U+Th/He dating of weathered goethite, and heavy mineral analysis. Based on this study, it...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Morphology; Sedimentology; Stratigraphy; Chronology; Tectonics; Paraíba Basin.
Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652012000200007
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Tectonic control on the stratigraphic framework of Late Pleistocene and Holocene deposits in Marajó Island, State of Pará, eastern Amazonia Anais da ABC (AABC)
Rossetti,Dilce F..
The traditional view that the Brazilian Amazonia is located in a tectonically stable area since the Cretaceous is changing in front of the increasing documentation of fault reactivations even during the Holocene. How the sedimentary record has responded to these events is an issue that remains to be approached with basis on field data. This work focuses on the stratigraphic correlation of late Quaternary deposits from eastern Marajó Island, with the goal of demonstrating the role of fault reactivation on the origin and preservation of these deposits. Despite the location in a stable platform of a continental passive margin, three studied stratigraphic units display significant vertical offsets that define two depocenters that are better explained through...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Amazonia; Tectonics; Quaternary; Stratigraphic framework; Radiocarbon dating; Sedimentation.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652010000200020
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Heavy mineral as a tool to refine the stratigraphy of kaolin deposits in the Rio Capim Area, Northern Brazil Anais da ABC (AABC)
Góes,Ana M.; Rossetti,Dilce F.; Mendes,Anderson C..
Studies of heavy minerals in kaolin deposits from the Ipixuna Formation in the Rio Capim area (Northern Brazil) showed a mature to super mature assemblage dominated by zircon and tourmaline, and subordinately rutile, kyanite and staurolite. These minerals do not change much throughout the whole section; however, each kaolin unit displays a particular signature, defined by differences in the proportions of the whole assemblage of heavy minerals, as well as of their textural characteristics. This work revealed that the lower and upper kaolin units can be definitely considered as distinct depositional sequences. A higher proportion of opaque minerals and higher zircon values characterize the lower unit. The higher volumes of anhedric, rounded to sub-rounded...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Heavy minerals; Kaolin deposits; Ipixuna Formation; Early Cretaceous; Cametá Sub-Basin.
Ano: 2007 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652007000300009
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Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil Anais da ABC (AABC)
Paz,Jackson D.S.; Rossetti,Dilce F..
An original and detailed study focusing the petrography of evaporites from the Late Aptian deposits exposed in the eastern and southern São Luís-Grajaú Basin is presented herein, with the attempt of distinguishing between primary and secondary evaporites, and reconstructing their post-depositional evolution. Seven evaporites phases were recognized: 1. chevron gypsum; 2. nodular to lensoidal gypsum or anhydrite; 3. fibrous to acicular gypsum; 4. mosaic gypsum; 5. brecciated gypsum or gypsarenite; 6. pseudo-nodular anhydrite or gypsum; and 7. rosettes of gypsum. The three first phases of gypsum display petrographic characteristics that conform to a primary nature. The fibrous to acicular and mosaic gypsum were formed by replacement of primary gypsum, but...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Evaporite; Petrography; Paleolake; Sabkha; Late Aptian; São Luís-Grajaú Basin.
Ano: 2006 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652006000300014
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Late quaternary dynamics in the Madeira river basin, southern Amazonia (Brazil), as revealed by paleomorphological analysis Anais da ABC (AABC)
Hayakawa,Ericson H.; Rossetti,Dilce F..
Ancient drainage systems are being increasingly documented in the Amazon basin and their characterization is crucial for reconstructing fluvial evolution in this area. Fluvial morphologies, including elongate belts, are well preserved along the Madeira River. Digital Elevation Model from the Shuttle Radar Topography Mission favored the detection of these features even where they are covered by dense rainforest. These paleomorphologies are attributed to the shifting position of past tributaries of the Madeira River through avulsions. These radial paleodrainage networks produced fan-shaped morphologies that resemble distributary megafans. Distinguishing avulsive tributary systems from distributary megafans in the sedimentary record is challenging. Madeira´s...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Paleochannels; Amazon Basin; Madeira river; Remote sensing; Climate; Tectonics.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000100029
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Marine influence in the Barreiras Formation, State of Alagoas, northeastern Brazil Anais da ABC (AABC)
Rossetti,Dilce F.; Góes,Ana M..
Tidal processes were important for deposition of the Barreiras Formation located in northern Brazil, while correlatable deposits in northeastern Brazil have been traditionally related to continental environments. Facies analysis in southern Alagoas revealed that the Barreiras Formation consists of cross-stratified conglomerates and sandstones (facies Sx and Cgx), compound cross-stratified sandstones (facies Cx), and heterolithic beddings (facies H). A significant portion of these deposits occurs within channel morphologies displaying fining and thinning upward successions. An abundance of sedimentary features is comparable to those from the northern Brazilian counterpart. These include: tidal bundles; herringbone cross-stratification; heterolithic beddings...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Miocene; Marine transgression; Tidal currents; Sedimentary structures; Northeastern Brazil.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652009000400012
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Late Quaternary drainage dynamics in northern Brazil based on the study of a large paleochannel from southwestern Marajó Island Anais da ABC (AABC)
Rossetti,Dilce F.; Góes,Ana M..
Marajó Island shows an abundance of paleochannels easily mapped in its eastern portion, where vegetation consists mostly of savannas. SRTM data make possible to recognize paleochannels also in western Marajó, even considering the dense forest cover. A well preserved paleodrainage network from the adjacency of the town of Breves (southwestern Marajó Island) was investigated in this work combining remote sensing and sedimentological studies. The palimpsest drainage system consists of a large meander connected to narrower tributaries. Sedimentological studies revealed mostly sharp-based, fining upward sands for the channelized features, and interbedded muds and sands for floodplain areas. The sedimentary structures and facies successions are in perfect...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Remote sensing; Sedimentology; Paleochannel; Marajó Island; Quaternary.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000300017
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Facies analysis of the Codó Formation (Late Aptian) in the Grajaú Area, Southern São Luís-Grajaú Basin Anais da ABC (AABC)
Rossetti,Dilce F.; Paz,Jackson D.S.; Góes,Ana M..
Facies descriptions of the Codó Formation in the Grajaú area are provided for the first time, and its sedimentary characteristics compared to those from the Codó area to allow paleoenvironmental reconstructions. Deposits in the Grajaú area include evaporites, limestones and argillites bearing features indicative of a shallow, low energy, subaqueous, saline environment exposed to meteoric and/or capillary conditions. Flooding-evaporative concentration-desiccation cycles suggest a saline pan complex surrounded by extensive evaporitic mudflats. The location of the system, whether coastal or inland, is a matter open for debate. However, the later hypothesis is favored considering: 1. Sr isotopic data, with values higher than those expected for Late Aptian...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Evaporite; Paleoenvironment reconstruction; Lacustrine; Late Aptian; Facies analysis; São Luís-Grajaú Basin.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652004000400012
Registros recuperados: 9
Primeira ... 1 ... Última
 

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