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  • 标题:New age determinations for the Banhadão and Itapirapuã complexes in the Ribeira Valley, southern Brazil
  • 其他标题:New age determinations for the Banhadão and Itapirapuã complexes in the Ribeira Valley, southern Brazil
  • 本地全文:下载
  • 作者:Gomes, Celso de Barros ; Azzone, Rogério Guitarrari ; Ruberti, Excelso
  • 期刊名称:Brazilian Journal of Geology
  • 印刷版ISSN:2317-4889
  • 出版年度:2018
  • 期号:AHEAD
  • 页码:0-0
  • DOI:10.1590/2317-4889201820170094
  • 出版社:Sociedade Brasileira de Geologia
  • 摘要:ABSTRACT: New age determinations by Ar-Ar and U-Pb SHRIMP for the alkaline complexes of Banhadão and Itapirapuã that occur in the Ribeira Valley are in agreement with the previously radiometric K-Ar ages available in literature. Ar-Ar ages on biotite for Banhadão range in the 106-110 Ma interval, and suggest a minimum age of 106 Ma for the complex. Ar-Ar data on biotite for Itapirapuã are more uniform, indicating an age of 102 Ma for the complex. U-Pb SHRIMP determinations on titanite from Itapirapuã melanite syenitic rocks yielded an age of ~106 Ma. Thus, the age interval of 100 and 110 Ma does exist indeed, suggesting an intermediate magmatic pulse between the already well-defined peaks of 80-90 Ma and 130-140 Ma for the alkaline rocks in southern Brazil, confirming the periodicity of the magmatism.
  • 其他摘要:ABSTRACT: New age determinations by Ar-Ar and U-Pb SHRIMP for the alkaline complexes of Banhadão and Itapirapuã that occur in the Ribeira Valley are in agreement with the previously radiometric K-Ar ages available in literature. Ar-Ar ages on biotite for Banhadão range in the 106-110 Ma interval, and suggest a minimum age of 106 Ma for the complex. Ar-Ar data on biotite for Itapirapuã are more uniform, indicating an age of 102 Ma for the complex. U-Pb SHRIMP determinations on titanite from Itapirapuã melanite syenitic rocks yielded an age of ~106 Ma. Thus, the age interval of 100 and 110 Ma does exist indeed, suggesting an intermediate magmatic pulse between the already well-defined peaks of 80-90 Ma and 130-140 Ma for the alkaline rocks in southern Brazil, confirming the periodicity of the magmatism.
  • 其他关键词:Alkaline rocks;Ponta Grossa Arch;Geochronology
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