(U)SAXS characterization of porous microstructure of chert: insights into organic matter preservation
Carregando...
Data
Data de publicação
Orientador
Título da Revista
ISSN da Revista
Título do Volume
É parte de
É parte de
É parte de
Journal of Applied Crystallography
Exportar
Resumo
This study characterizes the microstructure and mineralogy of 132 (ODP
sample), 1000 and 1880 million-year-old chert samples. By using ultra-smallangle X-ray scattering (USAXS), wide-angle X-ray scattering and other
techniques, the preservation of organic matter (OM) in these samples is
studied. The scarce microstructural data reported on chert contrast with many
studies addressing porosity evolution in other sedimentary rocks. The aim of this
work is to solve the distribution of OM and silica in chert by characterizing
samples before and after combustion to pinpoint the OM distribution inside the
porous silica matrix. The samples are predominantly composed of alpha quartz
and show increasing crystallite sizes up to 33 5 nm (1 standard deviation or
SD). In older samples, low water abundances (0.03%) suggest progressive
dehydration. (U)SAXS data reveal a porous matrix that evolves over geological
time, including, from younger to older samples, (1) a decreasing pore volume
down to 1%, (2) greater pore sizes hosting OM, (3) decreasing specific surface
area values from younger (9.3 0.1 m2 g 1
) to older samples (0.63
0.07 m2 g 1
, 1 SD) and (4) a lower background intensity correlated to
decreasing hydrogen abundances. The pore-volume distributions (PVDs) show
that pores ranging from 4 to 100 nm accumulate the greater volume fraction of
OM. Raman data show aromatic organic clusters up to 20 nm in older samples.
Raman and PVD data suggest that OM is located mostly in mesopores.
Observed structural changes, silica–OM interactions and the hydrophobicity of
the OM could explain the OM preservation in chert.
Como referenciar
MUNOZ, PATRICIO; ILAVSKY, JAN; NEWVILLE, MATTHEW; WETTER, NIKLAUS U.; LOURENÇO, RAFAEL A.; ANDRADE, MARCELO B. de; MARTINS, TEREZA S.; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; SILVA, LUIS C.C. da; OLIVEIRA, CRISTIANO L.P. (U)SAXS characterization of porous microstructure of chert: insights into organic matter preservation. Journal of Applied Crystallography, v. 56, p. 1692-1706, 2023. Part: 6. DOI: 10.1107/S1600576723008889. Disponível em: http://repositorio.ipen.br/handle/123456789/34437. Acesso em: 20 Mar 2026.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.