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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Petrology and Sr-Nd characteristics of the Nova Lacerda dike swarm, SW Amazonian Craton: new insights regarding its subcontinental mantle source and Mesoproterozoic geodynamics

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Autor(es):
Girardi, V. A. V. [1] ; Correa da Costa, P. C. [2] ; Teixeira, W. [1]
Número total de Autores: 3
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Geociencias, BR-01498 Sao Paulo - Brazil
[2] Univ Fed Mato Grosso, Inst Ciencias Exatas & Terra, Cuiaba - Brazil
Número total de Afiliações: 2
Tipo de documento: Artigo Científico
Fonte: INTERNATIONAL GEOLOGY REVIEW; v. 54, n. 2, p. 165-182, 2012.
Citações Web of Science: 8
Resumo

The NNW-trending Nova Lacerda tholeiitic dike swarm in Mato Grosso State, Central Brazil, intrudes the Nova Lacerda granite (1.46 Ga) and the Jauru granite-greenstone terrain (ca. 1.79-1.77 Ga). The swarm comprises diabases I and II and amphibolites emplaced at ca. 1.38 Ga. Geochemical data indicate that these are evolved tholeiites characterized by high LILE/HSFE and LREE/HSFE ratios. Isotopic modelling yields positive epsilon(Nd)(T) values (+0.86 to +2.65), whereas values for epsilon(Sr)(T) range from positive to negative (+1.96 to -5.56). Crustal contamination did not play a significant petrogenetic role, as indicated by a comparison of isotopic data (Sr-Nd) from both dikes and country rocks, and by the relationship between isotopic and geochemical parameters (SiO2, K2O, Rb/Sr, and La/Yb) of the dikes. We attribute the origin of these tholeiites to fractional crystallization of evolved melts derived from a heterogeneous mantle source. Comparison of the geochemical and isotopic data of the studied swarm and other tholeiitic Mesoproterozoic mafic intrusions of the SWAmazonian Craton the Serra da Providencia, Colorado, and Nova Brasilandia bimodal suites - indicates that parental melts of the Nova Lacerda swarm were derived from the most enriched mantle source. This enrichment was probably caused by the stronger influence of the EMI component on the DMM end-member. These data, coupled with trace element bulk-rock geochemistry of the country rocks, and comparisons with the Colorado Complex of similar age, suggest a continental-margin arc setting for the emplacement of the Nova Lacerda dikes. (AU)

Processo FAPESP: 07/58762-2 - Estudo do magmatismo basico em areas selecionadas: petrologia, geoquimica, geocronologia e metalogenese.
Beneficiário:Vicente Antonio Vitorio Girardi
Linha de fomento: Auxílio à Pesquisa - Regular