40Ar/39Ar constraints on the temporal evolution of Graciosa Island, Azores (Portugal)

Larrea, Patricia, Wijbrans, Jan R., Gale, Carlos, Ubide, Teresa, Lago, Marceliano, Franca, Zilda and Widom, Elisabeth (2014) 40Ar/39Ar constraints on the temporal evolution of Graciosa Island, Azores (Portugal). Bulletin of Volcanology, 76 2: . doi:10.1007/s00445-014-0796-8

Author Larrea, Patricia
Wijbrans, Jan R.
Gale, Carlos
Ubide, Teresa
Lago, Marceliano
Franca, Zilda
Widom, Elisabeth
Title 40Ar/39Ar constraints on the temporal evolution of Graciosa Island, Azores (Portugal)
Formatted title
40Ar/39Ar constraints on the temporal evolution of Graciosa Island, Azores (Portugal)
Journal name Bulletin of Volcanology   Check publisher's open access policy
ISSN 0258-8900
Publication date 2014-02-01
Year available 2014
Sub-type Article (original research)
DOI 10.1007/s00445-014-0796-8
Open Access Status Not yet assessed
Volume 76
Issue 2
Total pages 15
Place of publication Heidelberg, Germany
Publisher Springer
Language eng
Formatted abstract
Lava flows spanning the eruptive record of Graciosa Island (Azores archipelago) and a gabbro xenolith were dated by 40Ar/39Ar in order to constrain the Pleistocene and Holocene volcanic evolution of the island. The results range from 1.05 Ma to 3.9 ka, whereas prior published K-Ar and 14C ages range from 620 to 2 ka. The formation of the Serra das Fontes shield volcano started at minimum 1.05 Ma, and the magmatic system was active for ca. 600 ky, as suggested by the formation of the gabbro xenolith by magmatic differentiation. Evolved magmas making up the Serra das Fontes-Serra Branca composite volcano were generated at ca. 450 ka. After a period of ca. 110 ky of volcanic inactivity and erosion of volcanic edifices, volcanism was reactivated with the formation of the Vitória Unit NW platform. Later, the development of the Vulcão Central Unit started with the formation of monogenetic cones located to the south of the Serra das Fontes-Serra Branca-Vitória Unit. This volcanism became progressively more evolved and was concentrated in a main eruptive center, forming the Vulcão Central stratovolcano with an age older than 50 ka. The caldera related to this stratovolcano is older than 47 ka and was followed by effusion of basaltic magmas into the caldera, resulting in the formation of a lava lake, which ultimately spilled over the caldera rim at ca. 11 ka. The most recent eruptions on Graciosa formed two small pyroclastic cones within the caldera and the Pico do Timão cone within the Vitória Unit at ca 3.9 ka.
Keyword 40Ar/39Ar
Graciosa Island
Volcanic history
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID B023/10
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Earth Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 9 times in Thomson Reuters Web of Science Article | Citations
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