New volcanological, ⁴⁰Ar/³⁹Ar dating and paleomagnetic record from Trindade Island and stratigraphic implications

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Pasqualon, N. G. ; Lima, E. F. ; de Oliveira, W. P. ; Hartmann, G. A. ; Scherer, C. M. S. ; Rossetti, L. M. M. ; da Luz, F. R. ; Trindade, R. I. F. ; Cahoon, E. B. ; Miggins, D. P. ; Koppers, A. ; Di Chiara, A.

• Document type: Journal article
• Source: QUATERNARY GEOCHRONOLOGY; v. 81, p. 19-pg., 2024-04-05.

Abstract

Unrevealing the stratigraphy of volcanic systems is fundamental to understanding their eruptive history and requires a multiproxy approach for the accurate correlation and interpretation of deposits. We present new volcanological, Ar-40/Ar-39 ages and paleomagnetic data from the volcanic rocks of Trindade Island, located at similar to 1.260 km from the Brazilian coast in the South Atlantic Ocean. The reconstruction of the volcanic history of Trindade Island is important because it is the youngest volcanic terrain in Brazil and part of a submarine chain that represents the most recent plume-induced alkaline manifestation beneath the South American plate. Our results suggest Trindade Island underwent two main phases of volcanism. The first phase (3.9-1.5 Ma) formed the Trindade Complex and Desejado Formation, with eruptive styles ranging from phreatomagmatic/Surtseyan to Vulcanian and of dominant phonolitic composition. The second phase (1.0-0.06 Ma) formed the nephelinitic monogenetic centers Morro Vermelho, Valado and Pared & atilde;o Volcano Formations through dominant Hawaiian and Strombolian styles. The new ages imply a revised stratigraphy for the youngest units of Trindade Island, with partial overlap between them. The revised chronology integrated to the paleomagnetic directional data evidence that Trindade Complex formed during Gauss normal chron (D = 355.4 degrees; I = -49.6 degrees), Valado and Pared & atilde;o Volcano during Brunhes normal chron (D = 14 degrees; I = -42.3 degrees and D = 9.2 degrees; I = -35.2 degrees, respectively), while Morro Vermelho records the late Matuyama-early Brunhes chron (D = 36.5 degrees; I = -19.8 degrees), with site-level mean paleodirections of normal and transitional polarity within the reverse Matuyama interval. (AU)

• FAPESP's process: 19/22084-8 - The Paraná Magmatic Province: petrogenesis, chronology and environmental impact of Cretaceous tholeiitic, alkaline and silicic magmatism in the Brazilian Platform
• Grantee: Valdecir de Assis Janasi
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 22/03086-2 - Geomagnetic history of South America
• Grantee: Gelvam André Hartmann
• Support Opportunities: Research Grants - Initial Project