Magmatic evolution of Graciosa (Azores, Portugal)

Larrea, Patricia, Gale, Carlos, Ubide, Teresa, Widom, Elisabeth, Lago, Marceliano and Franca, Zilda (2014) Magmatic evolution of Graciosa (Azores, Portugal). Journal of Petrology, 55 11: 2125-2153. doi:10.1093/petrology/egu052

Author Larrea, Patricia
Gale, Carlos
Ubide, Teresa
Widom, Elisabeth
Lago, Marceliano
Franca, Zilda
Title Magmatic evolution of Graciosa (Azores, Portugal)
Journal name Journal of Petrology   Check publisher's open access policy
ISSN 1460-2415
Publication date 2014-11-01
Year available 2014
Sub-type Article (original research)
DOI 10.1093/petrology/egu052
Open Access Status Not yet assessed
Volume 55
Issue 11
Start page 2125
End page 2153
Total pages 29
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Language eng
Subject 1908 Geophysics
1906 Geochemistry and Petrology
Abstract Graciosa is the westernmost island of theTerceira Rift, located to the east of the Mid-Atlantic Ridge, in the Azores archipelago. The three volcanic complexes recognized in the island have been characterized, including the study of lava flows, gabbroic xenoliths (alkaline and subalkaline), syenites and dunites. A detailed study of mineral compositions and whole-rock major and trace element concentrations has allowed the characterization of volcanic units and the investigation of the magmatic and temporal evolution of the island. Lava flows from the three volcanic complexes, alkaline gabbros (cumulate origin) and syenites (bulk trachyte liquid origin) can be related by polybaric fractional crystallization starting at ~15 km depth; to explain the alternation of mafic and evolved products with time, magma chamber replenishment by primitive melts is needed. In contrast, the origin of the subalkaline gabbros, found for the first time in the Azores, appears to be related to fractionation of highly refractory melts at shallower levels (~3 km).The lack of significant crustal assimilation in most Graciosa samples suggests that the range in Sr-Nd-Pb isotope compositions probably reflects those of a predominantly FOZO-like mantle source. Enriched (EMI- and EMII-type) mantle source components, similar to those of São Miguel and Faial, have also been recognized for the first time in Graciosa.
Keyword Alkaline xenoliths
Magmatic differentiation
Subalkaline xenolith
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 8 times in Thomson Reuters Web of Science Article | Citations
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