Lifetime of an ocean island volcano feeder zone: constraints from U-Pb dating on coexisting zircon and baddeleyite, and 40Ar/39Ar age determinations, Fuerteventura, Canary Islands

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Version: Final published version
Serval ID
serval:BIB_A2B1184AC906
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Lifetime of an ocean island volcano feeder zone: constraints from U-Pb dating on coexisting zircon and baddeleyite, and 40Ar/39Ar age determinations, Fuerteventura, Canary Islands
Journal
Canadian Journal of Earth Sciences
Author(s)
Allibon J., Ovtcharova M., Bussy F., Cosca M., Schaltegger U., Bussien D., Lewin E.
ISSN-L
0008-4077
Publication state
Published
Issued date
2011
Peer-reviewed
Oui
Volume
48
Pages
567-592
Language
english
Abstract
High-precision isotope dilution - thermal ionization mass spectrometry
(ID-TIMS) U-Pb zircon and baddeleyite ages from the PX1 vertically
layered mafic intrusion Fuerteventura, Canary Islands, indicate
initiation of magma crystallization at 22.10 +/- 0.07 Ma. The magmatic
activity lasted a minimum of 0.52 Ma. Ar-40/Ar-39 amphibole dating
yielded ages from 21.9 +/- 0.6 to 21.8 +/- 0.3, identical within errors
to the U-Pb ages, despite the expected 1% theoretical bias between
Ar-40/Ar-39 and U-Pb dates. This overlap could result from (i) rapid
cooling of the intrusion (i. e., less than the 0.3 to 0.6 Ma 40Ar/39Ar
age uncertainties) from closure temperatures (T-c) of zircon (699-988
degrees C) to amphibole (500-600 degrees C); (ii) lead loss affecting
the youngest zircons; or (iii) excess argon shifting the plateau ages
towards older values. The combination of the Ar-40/Ar-39 and U/Pb
datasets implies that the maximum amount of time PX1 intrusion took to
cool below amphibole T-c is 0.8 Ma, suggesting PX1 lifetime of 520 000
to 800 000 Ma. Age disparities among coexisting baddeleyite and zircon
(22.10 +/- 0.07/0.08/0.15 Ma and 21.58 +/- 0.15/0.16/0.31 Ma) in a
gabbro sample from the pluton margin suggest complex genetic
relationships between phases. Baddeleyite is found preserved in
plagioclase cores and crystallized early from low silica activity magma.
Zircon crystallized later in a higher silica activity environment and is
found in secondary scapolite and is found close to calcite veins, in
secondary scapolite that recrystallised from plagioclase. close to
calcite veins. Oxygen isotope delta O-18 values of altered plagioclase
are high (+7.7), indicating interaction with fluids derived from
host-rock carbonatites. The coexistence of baddeleyite and zircon is
ascribed to interaction of the PX1 gabbro with CO2-rich
carbonatite-derived fluids released during contact metamorphism.
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01/10/2012 19:07
Last modification date
20/08/2019 15:08
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