New age determinations for the Banhadão and Itapirapuã complexes in the Ribeira Valley, southern Brazil

• Document type: Journal article
• Source: BRAZILIAN JOURNAL OF GEOLOGY; n. ahead, p. -, 2018.

Abstract

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. (AU)

• FAPESP's process: 12/06082-6 - The Paraná-Etendeka magmatic province in Brazil: temporal and petrologic relationships between the tholeiitic and alkaline magmatism and geodynamic implications
• Grantee: Excelso Ruberti
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/23399-4 - The alkaline magmatism: petrological and geochemical investigations
• Grantee: Celso de Barros Gomes
• Support Opportunities: Regular Research Grants