IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
artículos
Título:
Compression map, functional groups and fossilization: A chemometric approach (Pennsylvanian neuropteroid foliage, Canada).
Autor/es:
D`ANGELO, JOSÉ A; ZODROW, E L; MASTALERZ, M
Revista:
INTERNATIONAL JOURNAL OF COAL GEOLOGY
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2012 vol. 90-9 p. 149 - 155
ISSN:
0166-5162
Resumen:
Nearly all of the spectrochemical studies involving
Carboniferous foliage of seed-ferns are based on a limited number of pinnules,
mainly compressions. In contrast, in this paper we illustrate working with a larger
pinnate segment, i.e., a 22-cm long neuropteroid specimen, compression-preserved
with cuticle, the compression map. The objective is to study preservation
variability on a larger scale, where observation of transparency/opacity of constituent
pinnules is used as a first approximation for assessing the degree of pinnule
coalification/fossilization. Spectrochemical methods by Fourier transform infrared
spectrometry furnish semi-quantitative data for principal component analysis.
The compression map shows a high degree of preservation variability,
which ranges from comparatively more coalified pinnules to less coalified pinnules
that resemble fossilized-cuticles, noting that the pinnule midveins are preserved
more like fossilized-cuticles. A general overall trend of coalified pinnules
towards fossilized-cuticles, i.e., variable chemistry, is inferred from the semi-quantitative
FTIR data as higher contents of aromatic compounds occur in the visually more
opaque upper location of the compression map. The latter also shows a higher condensation
of the aromatic nuclei along with some variation in both ring size and degree
of aromatic substitution. From principal component analysis we infer correspondence between transparency/opacity
observation and chemical information which correlate with varying degree to fossilization/coalification
among pinnules.