CONICET | Buscador de Institutos y Recursos Humanos

Fronds of Ruflorinia orlandoi Carrizo and Del Fueyo, 2014 (Pteridospermophyta) are analyzed for the first time by semi-quantitative Fourier Transform Infrared (FTIR) spectroscopy with the aim of revealing mesophyll and cuticle chemical structures (functional groups) preserved in different frond parts (pinnae and raquis) as well as their relation with kerogen types. The specimens collected in the well-known oil-source Springhill Formation (Berriasian-Valanginian) at the Río Correntoso Locality (Santa Cruz, Argentina) are compressions with cuticular features very well-preserved (MPM-PB 15323-15330). For the spectrometric study pinnae and raquis were analyzed which in turn conform two sample forms: (1) compressions (including coalified mesophyll and cuticle) and (2) cuticles. The latter were obtained from compressions by chemical oxidation treatment. Semi-quantitative data were evaluated by principal component analysis (PCA) showing the behavior of the analyzed categories according to the functional groups. The results indicate that compressions have a similar chemical composition while cuticles show a greater variability. In the first case, the mesophyll may hide cuticular differences between specimens. In the second case, the observed variation may be due to the stage of fronds development and to the presence of trichomes and cuticular striations which are heterogeneously distributed on epidermises. Additionally, rachis show a higher aromatic carbon content than pinnae for each specimen, in both compressions and cuticles, which is in agreement with a more lignified tissue in rachis. Furthermore, the sample forms have a general chemical composition similar to Type II-kerogen which is characterized by intermediary aliphatic-groups values related to cuticles, spores, and resins.