Reprint of "Solid bitumen occurrences in the Arruda sub-basin (Lusitanian Basin, Portugal): Petrographic features

• Tipo: Artigo em Revista Científica Internacional
• Data: 2015

Autores

Goncalves, PA (Autor) FCUP; Mendonca Filho, JG (Autor) Outra; da Silva, FS (Autor) Outra; Flores, D (Autor) FCUP

Revista

Título: International Journal of Coal Geology

Vol. 139

Páginas: 217-227

ISSN: 0166-5162

Editora: Elsevier

Indexação

ISI Web of Knowledge - 12 Citações

Scopus - 0 Citações

Outras Informações

ID Authenticus: P-00G-49T

DOI: 10.1016/j.coal.2014.10.012

Abstract (EN): The Middle Jurassic to Cretaceous sedimentary record in the Lusitanian Basin (Portugal) reveals the presence of disseminated solid bitumen. The present work is focused on the petrographic characteristics of solid bitumen identified in the Freixial-1 and Benfeito-1 boreholes (Arruda sub-basin, Lusitanian Basin) that display different thermal maturities. Microscopy techniques (reflected and transmitted white light, incident blue light and SEM) and organic geochemistry analyses (total organic carbon, total sulfur and insoluble residue) were used to study these samples. From the results obtained by optical microscopy (fluorescence and reflectance) it was possible to distinguish three types of solid bitumen. They were labeled as solid bitumen A, present in all the samples, solid bitumen B and solid bitumen C, these ones observed in some of them. They correspond to allochthonous (migrated) bitumens. In blue incident light, some bitumen do not show fluorescence while others reveal fluorescence that range from yellow (solid bitumen B) to dark brown (solid bitumen A). All bitumens are optically isotropic. Bitumen reflectance varies between 0.70 and 2.60%R-r, and the vitrinite reflectance ranges from 1.11 to 1.48% R-r. Based on the % R-r values, the solid bitumen identified in these samples are classified as impsonite (epi- and cata-) or pyrobitumen. No relation can be established with confidence for the reflectance of bitumens with the reflectance of vitrinite.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11