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C- and Sr-isotope stratigraphy of the São Caetano complex, Northeastern Brazil: a contribution to the study of the Meso-Neoproterozoic seawater geochemistry Anais da ABC (AABC)
Silva,Juan C.; Sial,Alcides N.; Ferreira,Valderez P.; Pimentel,Márcio M..
C-isotope and 87Sr/86Sr values for five carbonate successions from the São Caetano Complex, northeastern Brazil, were used to constrain their depositional age and to determine large variations in the C- and Sr-isotopic composition of seawater under the framework of global tectonic events. Three C-isotope stages were identified from base to top in a composed chemostratigraphic section: (1) stage in which delta13C values vary from +2 to +3.7‰ PDB and average 3‰ PDB, (2) stage with delta13C values displaying stronger oscillations (from -2‰ to +‰ PDB), and (3) stage with an isotopic plateau with values around +3.7‰ PDB. Constant 87Sr/86Sr values (~ 0.70600) characterize C-isotope stage 1, whereas slightly fluctuating values (from 0.70600 to 0.70700)...
Tipo: Info:eu-repo/semantics/article Palavras-chave: C-isotopes; Meso-Neoproterozoic; Chemostratigraphy; Borborema Province; Northeastern Brazil.
Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652005000100011
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Combined U-Pb and Lu-Hf isotope analyses by laser ablation MC-ICP-MS: methodology and applications Anais da ABC (AABC)
Matteini,Massimo; Dantas,Elton L.; Pimentel,Marcio M.; Bühn,Bernhard.
The Lutetium-Hafnium isotopic system represents one of the most innovative and powerful tools for geochronology and isotopic studies. Combined U-Pb and Lu-Hf in situ analyses on zircon by LA-MC-ICP-MS permit to characterize isotopically the host magma from which it crystallized furnishing significant information for sediment provenance and crustal evolution studies. In this paper e describe the Lu-Hf systematic by LA-MC-ICP-MS developed in the laboratory of Geochronology of the University of Brasilia and report the results obtained by repeated analyses of 176Hf/177Hf isotopic ratio of three zircon standards: GJ-1 = 0.282022 ± 11 (n=56), Temora 2 = 0.282693 ± 14 (n=25) and UQZ = 0.282127 ± 33 (n=11). The 176Hf/177Hf ratio (0.282352 ± 22, n=14) of gem...
Tipo: Info:eu-repo/semantics/article Palavras-chave: LA-MC-ICP-MS; Lu-Hf; U-Pb; Zircon; Borborema Province.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652010000200023
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Conservation of geosites as a tool to protect geoheritage: the inventory of Ceará Central Domain, Borborema Province - NE/Brazil Anais da ABC (AABC)
MOURA,PÂMELLA; GARCIA,MARIA DA GLÓRIA M.; BRILHA,JOSÉ B.; AMARAL,WAGNER S..
ABSTRACT The Ceará Central Domain, in the northern Borborema Province/NE Brazil, encompasses important geological records (geosites) which allow understanding a relevant period of the Earth’s evolution, mainly associated to Neoproterozoic Brazilian/Pan-African Cycle and West Gondwana amalgamation, besides Neoarchean to Ordovician records. The presented geoheritage inventory aims to characterise the geosites with scientific relevance of Ceará Central Domain. By applying a method for large areas, the final selection resulted in eight geological frameworks represented by 52 geosites documented in a single database. This is the first step for a geoconservation strategy based on systematic inventories, statutory protection, geoethical behaviour and awareness...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Geological heritage; Geoconservation; Inventory; Borborema Province; Brazil.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652017000602625
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