Fourier transform Raman spectra of Czech and Moravian fossil resins from freshwater sediments

Abstract

Fourier Transform (FT) Raman spectra were obtained from 10 fossil resin specimens differing in localities, precise paleoecological situation and geological age. The series investigated includes amber from Moravia and Bohemia designated by local names: valchovite, retinite, neudorfite, schauffite and muckite. All fossil resins originate from freshwater deposits of Cenomanian age (Mesozoic). Non-altered amber from Jantarnaja (Baltic Russia), highly matured amber, rumanite and simetite and also přílepite of Westphalian age (Carboniferous) were investigated for comparison material. The FT-Raman spectra indicates the similarity between Bohemian and Moravian fossil resins and Baltic (Eocene) and Lebanon (Cretaceous) ambers. Important differences exist among the FT-Raman spectra obtained. Similarities between spectra of fossil resins of different ages, and differences between similar materials sampled at close localities, suggest the importance of the post-depositional conditions and alteration on the character of the resulting fossil resin.

Non-destructive analysis of amber artefacts from the prehistoric Cioclovina hoard (Romania)

“…If we focus on the spectral differences, we can observe that around 1614 cm À1 , a region associated with n (C]C) aromatic stretching, Romanite presents a characteristic medium intensity signal (Jehlicka et al, 2004), while Baltic amber presents only a weak intensity signal (Edwards and Farwell, 1996). Moreover, in most of the Baltic amber specimens, a weak intensity ester band of n (C]O) stretching was present at around 1739 cm À1 .…”

“…By examining the 1400e1700 cm À1 wavenumber region, all samples (controlled origin and archaeological) were found to be genuine amber specimens, based on the presence of the doublet formed by two strong signals at 1450 cm À1 and 1646 cm À1 , both assigned to n (C]C) stretching (Edwards and Farwell, 1996). In the 250e1400 cm À1 wavenumber region, common weak intensity signals for both Romanite and Baltic amber were observed at 1355 cm À1 , corresponding to d (CH 2 ) and d (CH 3 ) scissor vibrations; at 1299 cm À1 , corresponding to d (CH 2 ) and d (CH 3 ) twisting vibrations; at 1205 cm À1 , corresponding to d (CCH) and d (CeO) twisting vibrations; at 977 cm À1 , corresponding to r (CH 2 ) and r (CH 3 ) vibrations; and at around 716 cm À1 , corresponding to n (CC) isolated vibrations (Jehlicka et al, 2004).…”

“…In the wavenumber region 3200e2600 cm À1 , the spectra are all quite similar. All investigated samples display a broad band centred around 2930 cm À1 , assigned to n (CH 2 ) stretching, and a secondary band at 2872 cm À1 , assigned to n (CH 3 ) stretching (Edwards and Farwell, 1996;Jehlicka et al, 2004). By examining the 1400e1700 cm À1 wavenumber region, all samples (controlled origin and archaeological) were found to be genuine amber specimens, based on the presence of the doublet formed by two strong signals at 1450 cm À1 and 1646 cm À1 , both assigned to n (C]C) stretching (Edwards and Farwell, 1996).…”

“…It was recently suggested in the specialist literature that chemometric techniques could be applied with the advantage of improving the spectral recognition from background interference (Jehlicka and Edwards, 2008;Jehlicka et al, 2009). Important spectral features and the assignments of Raman bands have been published for fossil resins, including amber from different Cretaceous and Tertiary European sites by Edwards and Farwell (1996), Brody et al (2001), Winkler et al (2001Winkler et al ( , 2003 and Jehlicka et al (2004). The removal of the exomethylene group during progressive diagenesis in amber resins has also been described using FT-Raman spectroscopy (Brody et al, 2001).…”

“…In addition, we also applied complementarily Fourier transform Raman spectroscopy (FT-Raman) coupled with multivariate data analysis (MDA), with the aim of accurately identifying the origin of the investigated archaeological material. Over the last ten years, Raman spectroscopy has been used to identify several highly specific structural units or functional groups in complex mixtures of fossil resins (Jehlicka et al, 2004), allowing provenance studies to be undertaken quickly and non-destructively. It was recently suggested in the specialist literature that chemometric techniques could be applied with the advantage of improving the spectral recognition from background interference (Jehlicka and Edwards, 2008;Jehlicka et al, 2009).…”