Nannofossil biohorizons of the late Oligocene section of ODP Hole 120-748B from the Kerguelen Plateau, Southern Ocean (Table 2)
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| Format: | Dataset Open Access |
| Langue: | en |
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2006
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| _version_ | 1867169001863380992 |
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| author | Villa, Giuliana Persico, Davide |
| author_facet | Villa, Giuliana Persico, Davide |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Palaeoecological changes in nannofossil assemblages in the Southern Ocean during Oligocene times are examined through high-resolution, quantitative analyses of samples from Ocean Drilling Program (ODP) Site 748 (Kerguelen Plateau). We quantitatively characterized the palaeoecological preference of groups of species and compared their general trends with those determined at Maud Rise (ODP Sites 690 and 689) (Persico, D., Villa, G., 2004. Eocene-Oligocene calcareous nannofossils from Maud Rise and Kerguelen Plateau (Antarctica): palaeoecological and palaeoceanographic implications. Marine Micropaleontology 52, 153-179, doi:10.1016/j.marmicro.2004.05.002). We then attempt a correlation between the main assemblage variation and sea-surface temperature (SST) changes in the Southern Ocean at this time. Relatively stable, cool conditions are interpreted to have persisted from earliest to late Oligocene times, when an increase in abundance of temperate-water taxa is recorded, both at Maud Rise and Kerguelen Plateau, before the Mi-1 event. This reveals a climatic event that probably involved both sites, and which is comparable to that indicated by the global oxygen isotope curve ([Miller, K.G., Wright, J.D., Fairbanks, R.G., 1991. Unlocking the Ice House: Oligocene-Miocene oxygen isotopes, eustasy, and margin erosion. Journal of Geophysical Research, 96, 6829-6848, doi:10.1029/90JB02015; Zachos, J., Pagani, M., Sloan, L., Thomas, E., Billups, K., 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science, 292, 686-693, doi:10.1126/science.1059412.]). In the uppermost Oligocene at Site 689, the temperate-water taxa index ([temperate / temperate+cool]*100) increases from 25.2 Ma. Similarly, at Site 748, the temperate-water taxa index indicates an increase in SST in the late Oligocene, from about 26.5 Ma, at the base of Chron C8n.2n, which is offset by about 1 m.y. between the two areas. The reason for this time difference can probably be found in the location of Site 748 with respect to Site 689, and in the palaeoceanographic setting, taking into account that Site 748 lies north of a deep water passage that separates Kerguelen Plateau from Antarctica, and north of the present day front of the Antarctic Circumpolar Current. The presence of warm-water taxa, exclusively at Site 748, corroborates this hypothesis. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_693986 |
| institution | PANGAEA |
| language | en |
| publishDate | 2006 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Nannofossil biohorizons of the late Oligocene section of ODP Hole 120-748B from the Kerguelen Plateau, Southern Ocean (Table 2) Villa, Giuliana Persico, Davide 120-748B; Age model; Age model, Berggren et al (1995) BKSA95; Ageprofile Datum Description; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Joides Resolution; Leg120; Ocean Drilling Program; ODP; Sample code/label; Sample code/label 2; South Indian Ridge, South Indian Ocean Palaeoecological changes in nannofossil assemblages in the Southern Ocean during Oligocene times are examined through high-resolution, quantitative analyses of samples from Ocean Drilling Program (ODP) Site 748 (Kerguelen Plateau). We quantitatively characterized the palaeoecological preference of groups of species and compared their general trends with those determined at Maud Rise (ODP Sites 690 and 689) (Persico, D., Villa, G., 2004. Eocene-Oligocene calcareous nannofossils from Maud Rise and Kerguelen Plateau (Antarctica): palaeoecological and palaeoceanographic implications. Marine Micropaleontology 52, 153-179, doi:10.1016/j.marmicro.2004.05.002). We then attempt a correlation between the main assemblage variation and sea-surface temperature (SST) changes in the Southern Ocean at this time. Relatively stable, cool conditions are interpreted to have persisted from earliest to late Oligocene times, when an increase in abundance of temperate-water taxa is recorded, both at Maud Rise and Kerguelen Plateau, before the Mi-1 event. This reveals a climatic event that probably involved both sites, and which is comparable to that indicated by the global oxygen isotope curve ([Miller, K.G., Wright, J.D., Fairbanks, R.G., 1991. Unlocking the Ice House: Oligocene-Miocene oxygen isotopes, eustasy, and margin erosion. Journal of Geophysical Research, 96, 6829-6848, doi:10.1029/90JB02015; Zachos, J., Pagani, M., Sloan, L., Thomas, E., Billups, K., 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science, 292, 686-693, doi:10.1126/science.1059412.]). In the uppermost Oligocene at Site 689, the temperate-water taxa index ([temperate / temperate+cool]*100) increases from 25.2 Ma. Similarly, at Site 748, the temperate-water taxa index indicates an increase in SST in the late Oligocene, from about 26.5 Ma, at the base of Chron C8n.2n, which is offset by about 1 m.y. between the two areas. The reason for this time difference can probably be found in the location of Site 748 with respect to Site 689, and in the palaeoceanographic setting, taking into account that Site 748 lies north of a deep water passage that separates Kerguelen Plateau from Antarctica, and north of the present day front of the Antarctic Circumpolar Current. The presence of warm-water taxa, exclusively at Site 748, corroborates this hypothesis. |
| title | Nannofossil biohorizons of the late Oligocene section of ODP Hole 120-748B from the Kerguelen Plateau, Southern Ocean (Table 2) |
| topic | 120-748B; Age model; Age model, Berggren et al (1995) BKSA95; Ageprofile Datum Description; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Joides Resolution; Leg120; Ocean Drilling Program; ODP; Sample code/label; Sample code/label 2; South Indian Ridge, South Indian Ocean |
| url | https://doi.org/10.1594/PANGAEA.693986 |