Chemical Characterization and Botanical Origin of French Ambers
Abstract
The molecular composition of 10 Cretaceous andone Eocene ambers from France was analyzed by infraredspectroscopy, solid-state 13C nuclear magnetic resonance spectroscopy,and thermochemolysis gas chromatography−massspectrometry. The terpenoids identified in the samples wereused as biomarkers for the botanical origin of the resins. TheCretaceous samples, comprising the so-called Alpine, Anjou,Charentese, Provence, Pyrenean, and Vendean ambers, rangedfrom the Albian−Cenomanian transition to the early Santonian(100 to 85 Ma) and correspond to class Ib resins typical ofconifers. The extinct conifer family Cheirolepidiaceae wasproposed as the plant source of Pyrenean and brown Charenteseambers. Araucariaceae or Cheirolepidiaceae were the plant sourcesof the Cenomanian Alpine, Anjou, and yellow Charentese ambers.The Santonian ambers of Provence and Vendée were found to derive from the Cupressaceae. The Eocene Oise amber (ca. 53Ma) is a class Ic resin typical of angiosperms and was produced by a Fabaceae. The evolution of resin sources from the earlyCretaceous to the Eocene periods is discussed. Finally, a possible fingerprint hitherto unveiled is proposed for cheirolepidiaceousresins, defined by the simultaneous presence of phenolic diterpenoids, labdanoic acids, callitrisate structures, and their respectivederivatives.