Consulta: subjectFacets:"Isotopic composition"
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Data/hora: 12/06/2024 07:29:36

Li isotopic variations in single pyroxenes from the Northwest Africa 480 shergottite (NWA 480): a record of degassing of Martian magmas?
Provedor de dados: 5
Autores: Beck, Pierre; Barrat, J; Chaussidon, M; Gillet, P; Bohn, Marcel.
Lithium abundances and isotopic compositions were measured by ion microprobe in individual grains of pyroxene, and in a few maskelynites and Ca-phosphates grains, from the Martian meteorite Northwest Africa 480 (NWA 480).  In pyroxenes Li abundances are nearly constant from core to rim with concentrations ranging between 3 and 4 mug/g. In contrast, a significant isotopic zoning is observed with delta(7)Li values increasing within single crystals from similar to -17parts per thousand in the core to similar to +10parts per thousand in the rim, most of the variability being observed in the core. Plagioclase (now maskelynite) and phosphate crystals, which co-crystallized with the pyroxene rims, display similar delta(7) Li values. Because of the incompatible...
Tipo: Text
Palavras-chave: Mars planet; Magma; Pyroxene; Isotopic composition; Lithium; Geochemistry.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-735.pdf

Diffusion induced Li isotopic fractionation during the cooling of magmatic rocks: The case of pyroxene phenocrysts from nakhlite meteorites
Provedor de dados: 5
Autores: Beck, Pierre; Chaussidon, M; Barrat, J.a.; Gillet, Ph.; Bohn, Marcel.
Ion-microprobe was used to measure Li abundances and isotopic compositions in pyroxenes from three Martian meteorites belonging to the nakhlite family. The profiles performed across augite crystals from Northwest Africa 817 show a large isotopic zoning from crystal cores (delta Li-7 similar to 0 parts per thousand) to rims (delta Li-7 similar to +20 parts per thousand) while Li abundances are almost constant (similar to 9.2 mu g/g). Unlike NWA 817, the pyroxene studied in the Miller Range 03346 nakhlite shows a zoning in Li abundance, with concentrations increasing from similar to 2.5 mu g/g in the core to similar to 9 mu g/ g in the rim. The augite rim (delta Li-7 = +7 parts per thousand) is slightly enriched in Li-7 with regard to the core (delta Li-7 =...
Tipo: Text
Palavras-chave: Magma; Pyroxene; Lithium; Geochemistry; Mars planet; Isotopic composition.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1955.pdf

Carbon, nitrogen and natural abundance of δ13C e δ15N of light-fraction organic matter under no-tillage and crop-livestock integration systems - doi: 10.4025/actasciagron.v34i4.15061
Provedor de dados: 1
Autores: Loss, Arcângelo; Universidade Federal Rural do Rio de Janeiro; Pereira, Marcos Gervasio; Universidade Federal Rural do Rio de Janeiro; Perin, Adriano; Instituto Federal de Educação Ciência e Tecnologia Goiano; Beutler, Sidinei Julio; Universidade Federal Rural do Rio de Janeiro; Anjos, Lúcia Helena Cunha dos; Universidade Federal Rural do Rio de Janeiro.
This study aimed to quantify the light organic matter mass (LOM) in water, free light fraction (FLF) of soil organic matter (SOM) and carbon (C), nitrogen (N) contents and natural abundance of δ13C e δ15N contained in the mass of LOM, C and N in the FLF in land use systems in the Cerrado region of Goiás State, Brazil. Were evaluated a crop-livestock integration system - CLIS (corn+brachiaria/bean/cotton/soybean) and no-tillage system - NTS (sunflower/millet/soybean/corn). The vegetal coverage of natural Cerrado, adjacent to NTS and CLIS, was considered as the original soil condition. Soil samples were collected at depths of 0.0-5.0 and 5.0-10.0 cm in full random experimental design. The CLIS showed the greatest mass and levels of C-LOM (5-10 cm), and too...
Palavras-chave: Cerrado; Brachiaria; Plant residues; Isotopic composition; Physical indicators Cerrado; Brachiaria; Plant residues; Isotopic composition; Physical indicators.
Ano: 2012
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/15061