2024-03-28T12:31:42Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/549192021-06-24T08:01:52Zcom_10261_83com_10261_8com_10261_55com_10261_6com_10261_15com_10261_77col_10261_336col_10261_308col_10261_268col_10261_330
00925njm 22002777a 4500
dc
Almendros Martín, Gonzalo
author
Zancada Fernández, M. Cristina
author
González-Vila, Francisco Javier
author
Lesiak, M. A.
author
Álvarez Ramis, Concepción
author
2005-07
Przenosza (Western Carpathians, Poland) is an important palaeobotanical Cretaceous basement site with morphologically
well-preserved plant remains. Both the morphology of the macro remains and microscopic examination of isolated
plant cuticles reveal species typical of coastal swampy palaeoenvironments, mainly the fern Weichselia reticulata.
After isolation of the plant remains, preliminary characterisation of the fossil organic matter was carried out using
cross-polarization, magic angle spinning (CP-MAS) 13C Nuclear Magnetic Resonance (13C NMR) spectroscopy and
Curie point analytical pyrolysis.
The 13C NMR results suggested a type III kerogen from predominantly terrestrial material which was subjected to
intense diagenetic and catagenetic changes. The prominent resonance at ca. 130 ppm indicates C- or H-substituted aromatic
sub-units and the weak shoulder at ca. 153 ppm suggests removal of oxygen-containing groups from lignin and
carbohydrate. The aliphatic carbon signal (ca. 30 ppm) represents about a quarter of the total 13C signal intensity, suggesting
a significant contribution from selectively preserved aliphatic macromolecular structures.
Curie-point pyrolysis released a range of aromatic compounds and their alkylated derivatives, i.e. benzenes, phenols,
naphthalenes, anthracenes/phenanthrenes, fluorenes and pyrenes (probably derived from heavily altered aromatic biomacromolecules
such as lignin or tannins, or from secondary aromatisation of diagenetic structures). There was also a
series of n-alkane/n-alkene/a,x-alkadiene triplets. These range from C9 to C24 in carbon number, which is consistent
with the distributions found in previous studies of thermally altered cutan. Methoxyphenols, catechols, fatty acids, steroids,
diterpenes and sesquiterpenes were absent or present only in trace amounts. In contrast to the distributions of
aliphatic pyrolysis products, the lack of indicators for selectively preserved lignin, carbohydrate or protein, points to
an extensive rearrangement of phenolic constituents into a largely newly formed condensed backbone, where the original
lignin, waxes and carbohydrate were removed or became incorporated into a condensed kerogen matrix affected
by severe reduction, aromatization and additional cross-linking reactions.
Organic Geochemistry 36(7): 1108-1115 (2005)
0146-6380
http://hdl.handle.net/10261/54919
10.1016/j.orggeochem.2005.03.008
http://dx.doi.org/10.13039/501100007273
Molecular features of fossil organic matter in remains of the Lower Cretaceous fern Weichselia reticulata from Przenosza basement (Poland)