Back
Dinolagellate cysts palaeoenvironmental analysis of the Oligocene/Miocene transition in northwest and central Italy
| Zevenboom, D, Brinkhuis, H. and Visscher, H. | |
| 1994 | |
| Giornale di Geologia, ser. 3a, vol. 56/1 (1994): 155-169, Bologna | |
| Dinolagellate cysts palaeoenvironmental analysis of the Oligocene/Miocene transition in northwest and central Italy |
Zevenboom, D, Brinkhuis, H. and Visscher, H., 1994; Dinolagellate cysts palaeoenvironmental analysis of the Oligocene/Miocene transition in northwest and central Italy. Giornale di Geologia, ser. 3a, vol. 56/1 (1994): 155-169, Bologna Abstract: Detailed palynological investigations have been carried out on the Oligocene/Miocene (O/M) transition of the Contessa and Santa Croce di Arcevia sections (Umbria-Marche Basin, central Italy), emphasizing dinoflagellate cysts (dinocysts). Results are compared and combined with recently established information from the O/M GSSP section (Lemme section, Tertiary Piedmont Basin, NW Italy). The combined qualitative and quantitative dinocyst distribution patterns allow detailed correlations between the sections. In addition, the quantitative dinocyst record enables the recognition of sea-level and sea surface temperature (SST) fluctuations. These are used to further strengthen correlations made on the basis of the qualitative dinocyst information. The sea-level and SST-trends allow for recognition of six "third order" cycles. The cycles appear to match those of the third order "Exxon curve" in the O/M interval, reflecting their cycles TB 1.3 to TB 2.2., although one additional cycle is inferred within TB 1.4. The relationship between the sea-level and SST trends suggests glacio-eustasy as an underlying mechanism for the recorded third order cyclicity. The dinocyst-based correlations match relatively well with previously established calcareous plankton records. Combined evidence now indicates that previous interpretations of the magnetostratigraphic succession of the Contessa sequence across the O/M transition can be further refined. Key words: dinoflagellate cysts, biostratigraphy, palaeoecology, sequence stratigraphy, Oligocene/Miocene transition, central Italy.