کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4407279 1307367 2006 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Origin of pedogenic needle-fiber calcite revealed by micromorphology and stable isotope composition—a case study of a Quaternary paleosol from Hungary
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Origin of pedogenic needle-fiber calcite revealed by micromorphology and stable isotope composition—a case study of a Quaternary paleosol from Hungary
چکیده انگلیسی

Pedogenic needle-fiber calcite was studied regarding its morphology, texture and stable isotope composition from the paleosol of the Quaternary Várhegy travertine (Budapest, Hungary). The needle-fiber calcite is composed of 40–200 μm long monocrystals. Smooth rods as well as serrated-edged crystals with calcite overgrowths were identified by SEM. Needles have several textural varieties: randomly distributed crystals in vugs and pores with calcite hypocoatings, bundles of subparallel crystals forming coatings around grains and alveolar structure with bridging needles in vugs.The morphological study of needle-fiber calcite suggests that needles are calcified fungal sheaths and produced by fungal biomineralization, a common process in recent and fossil soils and calcretes. The stable isotope composition of needle-fiber calcite (average: δ18O=-7.1‰δ18O=-7.1‰ and δ13C=-7.3‰δ13C=-7.3‰ vs. V-PDB) indicates significant incorporation of organically derived CO2 and probably biological influence on needle genesis. Dissolved host rock travertine and/or atmospheric CO2 could also contribute some carbon to the acicular calcite.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemie der Erde - Geochemistry - Volume 66, Issue 3, 4 September 2006, Pages 203–212
نویسندگان
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