Tectonic significance of the Florianopolis Dyke Swarm, Parana-Etendeka Magmatic Province: A reappraisal based on precise U-Pb dating

Author(s)

Florisbal, Luana Moreira ^[1] ; Heaman, Larry M. ^[2] ; Janasi, Valdecir de Assis ^[1] ; Bitencourt, Maria de Fatima ^[3]

Affiliation

^[1] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo - Brazil

^[2] Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E3 - Canada

^[3] Univ Fed Rio Grande do Sul, Inst Geociencias, Ctr Estudos Petr & Geoquim, BR-91500000 Porto Alegre, RS - Brazil

• Document type: Journal article
• Source: JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH; v. 289, p. 140-150, DEC 1 2014.
• Web of Science Citations: 31

Abstract

The first precise ID-TIMS U-Pb baddeleyite/zircon dating of dykes representative of the main activity in the Florianopolis Dyke Swarm (Parana-Etendeka Magmatic Province, south Brazil) reveals a restricted age range (134.7 +/- 03 to 133.9 +/- 0.7 Ma). This is at least 5 Ma older than indicated by previous Ar-40/Ar-39 stepwise heating dating, and precludes a direct relationship with syn-rifting magmatism connected with opening the south Atlantic Ocean. Instead, as indicated by their age and geochemical signature, these dykes are feeders to the nearby Urubici lavas (and coeval Khumib lavas in Etendeka). These new geochronological results also cast doubt on a large (>10 Ma) time span for the emplacement of the Florianopolis Dyke Swarm implied by Ar-40/Ar-39 dates, but the determination of its upper age limit still requires accurate dating of younger, low-volume fine-grained dykes with distinct low-Ti chemistry; crystals suitable to U-Pb dating were not obtained thus far from these dykes. (C) 2014 Elsevier B.V. All rights reserved. (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: 11/09673-2 - Age, duration and tectonic significance of the Florianópolis dyke swarm, Província Magmática Paraná-Etendeka, by the combination of petrologic and U-Pb dating in baddeleyte and zircon studies
• Grantee: Luana Moreira Florisbal
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/13180-4 - ID-TMS U-Pb dating of baddeleyites from the Florianópolis dyke swarm
• Grantee: Luana Moreira Florisbal
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor