The chemical composition of Dicroidium (Corystospermales, Coristospermaceae). New insights from infrared spectroscopy analysis.

J. A. DANGELO; L. B. ESCUDERO ; W. VOLKHEIMER.

Mar del Plata

Simposio; XIV SIMPOSIO ARGENTINO DE PALEOBOTÁNICA Y PALINOLOGÍA; 2009

Universidad Nacional de Mar del Plata

Several specimens of Dicroidium odontopteroides var. odontopteroides (Morris) Gothan from the Triassic of Cacheuta, Mendoza, Argentina have been analyzed by Fourier Tranform Infrared Spectrometry (FTIR) ans Scanning Electron Microscopy analysis (SEM). Fossil remains are preserved as compressions by Schulze´s maceration process exhibited an excellently preserved morphological structure as evidenced by SEM. The high degree of cuticular preservation prompted this chemical study of Dicroidium, a well- known and dominant element of the terrestrial habitats og Gondwana during the Triassic. In order to improve the qualitative information provided by FTIR technique, different treatments of digitalized FTIR spectra have been applied, which allowed to obtain semi-quantitative data on chemical composition of fossil cuticles. Thus, Fourier self-deconvolution and curve-fitting methods have been employed to separate overlapping bands in composite profiles of cuticles. As a result this analysis, several functional groups were detected in the cuticular structure of the Dicroidium remains studied herein, namely C-H (in alkyl and aryl ethers and esters); C-O (in phenols and aryl and alkyl ethers); C-O and O-H (in phenoxy structures and ethers); Carbonyl groups (in carboxylic acids and conjugated and highly conjugated structures such as ketones) and C=C (in aromatic carbon structures). This novel quantitative determination of chemical structures by FTIR in fossil plants and related sedimentary materials (coal, kerogen) if characteristic, could be useful for oil-oil and oil-source rock correlation in certain Mesozoic southern hemisphere basins.