New age determinations for the Banhadao and Itapirapua complexes in the Ribeira Valley, southern Brazil

Author(s)

Gomes, Celso de Barros ; Azzone, Rogerio Guitarrari ; Ruberti, Excelso ; de Vasconcelos, Paulo Marcos ; Sato, Kei ; Enrich Rojas, Gaston Eduardo

• Document type: Journal article
• Source: BRAZILIAN JOURNAL OF GEOLOGY; v. 48, n. 2, p. 12-pg., 2018-04-01.

Abstract

New age determinations by Ar-Ar and U-Pb SHRIMP for the alkaline complexes of Banhadao and Itapirapua 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 Banhadao range in the 106-110 Ma interval, and suggest a minimum age of 106 Ma for the complex. Ar-Ar data on biotite for Itapirapua are more uniform, indicating an age of 102 Ma for the complex. U-Pb SHRIMP determinations on titanite from Itapirapua melanite syenitic rocks yielded an age of similar to 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: 16/23399-4 - The alkaline magmatism: petrological and geochemical investigations
• Grantee: Celso de Barros Gomes
• Support Opportunities: Regular Research Grants
• 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