Anisotropy of magnetic susceptibility of silicic rocks from quarries in the vicinity of Sao Marcos, Rio Grande do Sul, South Brazil: Implications for emplacement mechanisms

Author(s)

Canon-Tapia, Edgardo ; Raposo, M. Irene B.

• Document type: Journal article
• Source: JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH; v. 355, p. 16-pg., 2018-04-15.

Abstract

The Parana-Etendeka Large Igneous Province includes acid volcanic rocks that can be found throughout its extension. Several aspects concerning those rocks remain controversial, including their mechanism of emplacement and location of their eruptive sources. Opening of several quarries of dimension stone near the city of Sao Marcos, Rio Grande do Sul, Brazil, offers a unique opportunity to study in detail the acid products. Here, we present the results of a study of the anisotropy of magnetic susceptibility (AMS) completed in some rocks that had been interpreted as the roots of volcanic conduits. Our results, and reexamination of the textural features of the rocks, lead to a reinterpretation that suggests that these rocks were emplaced subaerially, and involved assimilation and remelting of clastic components of previous products. Due to the inferred conditions of emplacement, it is unlikely that the eruptive vents are located far from the area of study, therefore ruling out the long-travelled nature of these products. (C) 2017 The Authors. Published by Elsevier B.V. (AU)

• FAPESP's process: 14/12476-2 - The Paraná magmatic Province-Etendeka in Brazil: petrological and temporal relations between the tholeiitic and alkaline magmatism and its geodynamic implications
• Grantee: Maria Irene Bartolomeu Raposo
• Support Opportunities: Research Grants - Visiting Researcher Grant - International
• 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