کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4407204 1307356 2008 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Carbonate xenoliths in La Palma: Carbonatite or alteration product?
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Carbonate xenoliths in La Palma: Carbonatite or alteration product?
چکیده انگلیسی

Carbonate xenoliths containing olivine and rimmed by kaersutitic amphibole were collected in basaltic rocks of the Basal Complex of La Palma. The mineralogical composition and microscopic appearance may suggest a relationship with carbonatites in general, thus a major element, trace element and stable isotope study was conducted to investigate the origin of the carbonate formation. Based on electron microprobe analyses, the carbonate is calcite with up to 6.3 wt% MgO and 7.2 wt% SiO2. The elevated SiO2 content may suggest a melt origin for the carbonate. However, the C and O isotope compositions of the carbonate xenoliths (δ13C and δ18O around −1‰ and 13‰, respectively) are similar to those of calcite veins and amygdales in basaltic rocks of the Basal Complexes of La Palma and Fuerteventura and are interpreted as produced by fluid degassing and metasomatism by CO2–H2O fluid derived from mobilization of sedimentary material. Trace element contents determined by laser-ablation ICP-MS analyses support the assumed origin, thus, the relationship with carbonatitic melts can be excluded. Based on trace element compositions, the amphibole surrounding the xenoliths is not related genetically to the carbonate. The elevated SiO2 content of the calcite can be attributed to submicron relics of pyroxene, thus, the use of this feature as an evidence for melt origin is questionable.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemie der Erde - Geochemistry - Volume 68, Issue 4, 25 September 2008, Pages 369–381
نویسندگان
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