title: Spectroscopic studies of wood fossils from the Crato Formation, Cretaceous Period.
abstract: In this work we study two types of wood fossils (Gymnosperms, Araucariaceae) from the Crato Formation of Araripe Basin in Brazil, from the Cretaceous Period. The samples were characterized by Raman and infrared spectroscopies, X-ray diffraction and scanning electron microscopy. The results obtained by different techniques showed that although the rocks surrounding the fossils have predominantly the same constitution - calcite - however, the formation processes of these types of wood fossils are quite different. One of the fossils, denominated as light wood, is predominantly composed of gypsum, while the other fossil, the dark wood, is rich in amorphous carbon, possibly the kerogen type. Implications relative to the environment where the plants lived millions years ago are also given. Finally, the results highlight the constitution of one of the most important paleontological sites of the Cretaceous Period in the South America.
authors.affiliation: Campus Cariri, Universidade Federal do Ceará, 63000-000 Juazeiro do Norte, CE, Brazil.
authors.forename: J H
authors.initials: JH
authors.lastname: da Silva
authors.forename: P T C
authors.initials: PT
authors.lastname: Freire
authors.forename: B T O
authors.initials: BT
authors.lastname: Abagaro
authors.forename: J A F
authors.initials: JA
authors.lastname: Silva
authors.forename: G D
authors.initials: GD
authors.lastname: Saraiva
authors.forename: F J
authors.initials: FJ
authors.lastname: de Lima
authors.forename: O A
authors.initials: OA
authors.lastname: Barros
authors.forename: R A
authors.initials: RA
authors.lastname: Bantim
authors.forename: A A F
authors.initials: AA
authors.lastname: Saraiva
authors.forename: B C
authors.initials: BC
authors.lastname: Viana
mesh_terms: D001938:Brazil; D005580:Fossils; D055593:Geological Phenomena; D061848:Optical Imaging; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D013997:Time Factors; D014934:Wood / Q000737:chemistry* / Q000648:ultrastructure; D014961:X-Ray Diffraction
keywords: Cretaceous Period; Infrared spectroscopy; Raman spectroscopy; Wood fossils; X-ray diffraction