Mineralogical analysis of banded rhyolites Chapecó type of the Paraná Magmatic Province

• Grant number: 17/03515-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2017
• End date: April 30, 2018
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Fabio Ramos Dias de Andrade
• Grantee: Ana Paula Agostinelli dos Santos
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 12/06082-6 - The Paraná-Etendeka magmatic province in Brazil: temporal and petrologic relationships between the tholeiitic and alkaline magmatism and geodynamic implications, AP.TEM

Abstract

Volcanic rocks of the Paraná Basin are an important information source about geological processes not completely understood yet, partly because there is no analogous volcanism in historical time that could be observed directly. While basaltic rocks are extensively studied in their various geological, petrological and geochemical aspects, acidic volcanic rocks are relatively less well known and offer interesting puzzles as to their origin. Acid rocks, formed from magmas more viscous than those of basaltic rocks, probably formed from more explosive eruptions and led to the formation of a greater abundance of volcanic glass, partly still preserved in the south and southeast of the Brazil. There is no definitive interpretation on the solidification of acidic rocks, with models that consider the solidification of lava and others that consider the crystallization of welded tufts or reign ignimbrite. The devitrification features can bring important information to the processes of solidification of acid magmas (or ashes), helping to elucidate the eruption style of the final stages of the volcanism of the Magmatic Province of Paraná.