Lochkovian (earliest Devonian) miospores from the Solimões Basin, northewestern Brazil

RUBINSTEIN, C.V., MELO, J. H. G., STEEMANS, P

REVIEW OF PALAEOBOTANY AND PALYNOLOGY

Elsevier

Lugar: Amsterdam; Año: 2005 vol. 133 p. 91 - 113

0034-6667

Eighteen core samples from PETROBRAS well 1-JD-1-AM (Jandiatuba area, Solimões Basin, northwestern Brazil), have been studied for miospores. Fifty-three species have been identified. This assemblage is tentatively correlated with the Z Phylozone of the BZ Oppel Zone (Steemans, 1989), dated late Lochkovian.  This is in accordance with previous age determinations based on chitinozoans and acritarchs. Numerous representatives of the miospore genus Dictyotriletes have been observed. They enable us to propose the D. emsiensis Morphon, which includes D. granulatus, D. emsiensis, D. cf. subgranifer, specimens previously misassigned to D. subgranifer, and some Dictyotriletes spp. provisionally left in open nomenclature. Since all intermediate forms from typical D. granulatus to typical D. emsiensis coexist, it is currently difficult to determine the base of E Interval Biozone in South America as originally defined in Western Europe (Steemans, 1989). Therefore, we suggest that the base of the Ems Biozone of Melo and Loboziak (2001, 2003) cannot be correlated with the base of the E Biozone. Instead, it should be included in an interval of uncertainty ranging from the Si to the E Biozones (Steemans, 1989). Indeed, the underlying NsZ Biozone of Melo and Loboziak (2001) contains species not known below the Si Biozone (Steemans, 1989). We erect here a D. emsiensis Morphon Assemblage Zone, which may be coeval with the N through E biozones of Western Europe. The PISA palynoflora (Dino and Rodrigues, 1995), in the Paraná Basin, is also attributed to this new biozone. However, in the absence of species observed in the BZ Biozone (and also in the Solimões Basin), the PISA assemblage could be somewhat older than that of well 1-JD-1-AM.