W. Teixeira
University of Sao Paulo, Mineralogy and Geotectonics, Department Member
- Universidade de Lisboa, Departamento de Mineralogia e Geotectônica, Department Memberadd
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The Eastern Ghats granulite belt along the east coast of Peninsular India has a polyphase deformation and complex metamorphic record. Moreover, geochronological record indicated two distinct crustal domains, namely, Eastern Ghats Province... more
The Eastern Ghats granulite belt along the east coast of Peninsular India has a polyphase deformation and complex metamorphic record. Moreover, geochronological record indicated two distinct crustal domains, namely, Eastern Ghats Province and Ongole domain, separated by the Godavari graben. The most predominant granulite facies event in the Eastern Ghats Province is of Grenvillian age, as recorded from different lithologies and different segments of this large granulite terrane. Around Jeypore, at the western margin of the Eastern Ghats Province, the dominant lithology is massif-type charnockite with abundant mafic enclaves and xenoliths. A crustal scale shear zone at the western margin affected both the charnockitic assemblage and the cratonic assemblages. U-Pb dating of zircons from charnockite and cratonic assemblages indicates a strong thermal imprint around 2.5 Ga. Most importantly, no Grenvillian imprint is recorded in any of these assemblages, and this implies an exotic terrane later incorporated into the Eastern Ghats Province, possibly during the Grenvillian orogeny.
Research Interests: Geology and Shear Zone
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The Figueira Branca Suite (FBS) comprises a layered mafic–ultramafic complex which together with mafic–felsic plugs makes up a string of NW-trending intrusive bodies that are emplaced into the Jauru domain (Rio Negro-Juruena province;... more
The Figueira Branca Suite (FBS) comprises a layered mafic–ultramafic complex which together with mafic–felsic plugs makes up a string of NW-trending intrusive bodies that are emplaced into the Jauru domain (Rio Negro-Juruena province; 1.80–1.60Ga). This domain comprises Orosirian calc-alkaline rocks and coeval metamorphic volcanic–sedimentary associations, intruded by voluminous granitoid plutons resulted from outboard Cachoeirinha (1587–1522Ma) and Santa Helena (1485–1420Ma) accretionary
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... as young as 2125 ± 4 Ma (Machado et al., 1996), this formation also contrasts ... SFC as recorded by the regional deformation and metamorphism overprinting the Archean complexes ... to these authors the orogenic collapse, which was... more
... as young as 2125 ± 4 Ma (Machado et al., 1996), this formation also contrasts ... SFC as recorded by the regional deformation and metamorphism overprinting the Archean complexes ... to these authors the orogenic collapse, which was responsible for the dome-and-keel structure of ...
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The mafic/ultramafic Ipanema Layered Complex (ILC), Minas Gerais, Brazil, consists of seven individual bodies. These units crosscut polyphase orthogneisses and interlayered paragneisses of the Paleoproterozoic Juiz de Fora Complex.... more
The mafic/ultramafic Ipanema Layered Complex (ILC), Minas Gerais, Brazil, consists of seven individual bodies. These units crosscut polyphase orthogneisses and interlayered paragneisses of the Paleoproterozoic Juiz de Fora Complex. Intrusive granitoids tectonically related to the Neoproterozoic Araçuaí orogen are also present in the study area.A Sm-Nd whole-rock linear array for seven samples (metapyroxenites, metaperidotites, metagabbro, and meta-anorthosite) from the Santa
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Research Interests: Geology, Geochemistry, Chemical Geology, Metasomatism, Dike, and 3 moreBasalt, Petrogenesis, and Andesite
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... Complex reveal distinct isotopic characteristics for three granitoids, although the obtained signatures are consistent with the idea that the Rondonian-San Ignacio orogeny makes up ... Santos, JOS, Hartmann, LA, Gaudette, HE, Groves,... more
... Complex reveal distinct isotopic characteristics for three granitoids, although the obtained signatures are consistent with the idea that the Rondonian-San Ignacio orogeny makes up ... Santos, JOS, Hartmann, LA, Gaudette, HE, Groves, DI, McNaughton, NJ, and Fletcher, IR, 2000. ...
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The Aguapei basin from Central-Western Brazil (Amazonian Craton) has been interpreted as a NNW/SSE aulacogen associated with the development of the WNW-trending Sunsas Belt. Proterozoic reconstructions have considered the Sunsas belt as a... more
The Aguapei basin from Central-Western Brazil (Amazonian Craton) has been interpreted as a NNW/SSE aulacogen associated with the development of the WNW-trending Sunsas Belt. Proterozoic reconstructions have considered the Sunsas belt as a counterpart of the Grenville belt produced during the Laurentia-Amazonia collision at the end of the Mesoproterozoic (1300-950 Ma). Samples from 51 layers of sediments from the Aguapeí Group have been collected for paleomagnetic studies. Twenty five levels are sub-horizontal while the remainder have variable inclinations, and were collected for a fold test. Alternating field and thermal demagnetizations on the sub-horizontal sediments yielded a northern (southern) direction with a moderate to steep upward (downward) inclinaton. This magnetization is generally carried by magnetite in light to dark grey sediments, and by hematite in red sediments. Most of the grey sediments have acquired its magnetization during reverse (downword) polarity while the red ones present a normal (upward) polarity. Preliminary mean directions for normal (Dm=339.3°, Im=-58.4°; a95=9.4°, K=22.5, N=12) and reverse (Dm=205.2°, Im=57.8°; a95=9.3°, K=52.8, N=6) polarities yielded poles at 153.1°E, 58.1N° (A95=11.9°) and 263.8°E, -57.5°S (A95=12.7°), respectivelly. They plot in-between the recently obtained 1.2 Ga Nova Floresta pole and the pole obtained for mafic rocks (sills) that cut the Aguapei sediments (DAgrella-Filho et al., this volume). Our results suggest an Amazonia-Laurentia collision after 1.2 Ga.
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We report three new paleomagnetic poles from the Amazon craton for the Meso/Neoproterozoic Grenvillian interval, a period notable for the eponymous continental collision that affected the eastern margin of Laurentia. The poles were... more
We report three new paleomagnetic poles from the Amazon craton for the Meso/Neoproterozoic Grenvillian interval, a period notable for the eponymous continental collision that affected the eastern margin of Laurentia. The poles were derived from study of ca.1230 Ma mafic sills (Figueira Branca -V 40Ar/39Ar biotite), the 1149 ,b7 Ma sediments of the Aguapeí Gp. (U-Pb SHRIMP analysis of authigenic