Oxygen isotope thermometry in carbonatites, Fuerteventura, Canary Islands, Spain

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doi: 10.1007/s00710-003-0022-4
Authors:Demény, A.; Vennemann, T. W.; Ahijado, A.; Casillas, R.
Volume Title:Mineralogy and Petrology
Source:Mineralogy and Petrology, 80(3-4), p.155-172. Publisher: Springer-Verlag, Vienna, Austria. ISSN: 0930-0708
Publication Date:2004
Note:In English; illus., incl. 3 tables, geol. sketch map
Summary:Crystallization temperatures of the oceanic carbonatites of Fuerteventura, Canary Islands, have been determined from oxygen isotope fractionations between calcite, silicate minerals (feldspar, pyroxene, biotite, and zircon) and magnetite. The measured fractionations have been interpreted in the light of late stage interactions with meteoric and/or magmatic water. Cathodoluminescence characteristics were investigated for the carbonatite minerals in order to determine the extent of alteration and to select unaltered samples. Oxygen isotope fractionations of minerals of unaltered samples yield crystallization temperatures between 450 and 960 °C (average 710 °C). The highest temperature is obtained from pyroxene-calcite pairs. The above range is in agreement with other carbonatite thermometric studies. This is the first study that provides oxygen isotope data coupled with a CL study on carbonatite-related zircon. The CL pictures revealed that the zircon is broken and altered in the carbonatites and in associated syenites. Regarding geological field evidences of syenite-carbonatite relationship and the close agreement of published zircon U/Pb and whole rock and biotite K/Ar and Ar-Ar age data, the most probable process is early zircon crystallization from the syenite magma and late-stage reworking during magma evolution and carbonatite segregation. The oxygen isotope fractionations between zircon and other carbonatite minerals (calcite and pyroxene) support the assumption that the zircon would correspond to the early crystallization of syenite-carbonatite magmas. [H.P.B.]
Sections:Geochemistry
Subsections:Igneous rocks
Subjects:Baddeleyite; Carbonatites; Cathodoluminescence; Geologic thermometry; Igneous rocks; Islands; Isotope ratios; Isotopes; Nesosilicates; O-18/O-16; Orthosilicates; Oxides; Oxygen; Silicates; Stable isotopes; Volcanoes; Zircon; Zircon group; Atlantic Ocean Islands; Canary Islands; Fuerteventura
Coordinates:N282500 N282500 W0140000 W0140000
Abstract Numbers:04M/1641
Record ID:2010054293
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe
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