Carbon and oxygen stable isotope composition of bulk sediment and abundance of Braarudospahaera in ODP Site 122-762 (Table 1)
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| Format: | Dataset Open Access |
| Langue: | en |
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PANGAEA
1992
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| _version_ | 1867169967613411328 |
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| author | Siesser, William G Bralower, Timothy J De Carlo, Eric Heinen |
| author_facet | Siesser, William G Bralower, Timothy J De Carlo, Eric Heinen |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Nannofossil assemblages enriched in Braarudosphaera occur in lower Oligocene to lower Miocene sediments at Ocean Drilling Program Sites 762 and 763 on the central Exmouth Plateau. Braarudosphaerids appear here rather abruptly in the lower Oligocene (in Zone NP21). They reach their greatest numbers in the lower Oligocene (in Zones NP22 and NP23), where they comprise up to 10% of some samples. Braarudosphaera bigelowii is the overwhelmingly dominant species, occurring together with rare specimens of B. discula and Micrantholithus pinguis. The holococcoliths Peritrachelina joidesa and Lantemithus minutus are also associated with the Braarudosphaera enrichment. There are two populations of B. bigelowii: one of normal size (10-14 µm) and one of large specimens (20-22 µm). The larger braarudosphaerids are more common than the smaller forms. Braarudosphaera-rich sediments are absent at Wombat Plateau sites during the same time interval. We attribute this to latitudinal control, because the Wombat sites are about 4° north of the central Exmouth Plateau sites. We believe that the occurrence of braarudosphaerids is related to an Oligocene to early Miocene oceanographic event on the Exmouth Plateau. We suspect that mid-ocean up welling of cool, low-salinity, nutrient-rich water along a divergent zone created the Braarudosphaera-nch sediments in the South Atlantic and Indian oceans. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_729251 |
| institution | PANGAEA |
| language | en |
| publishDate | 1992 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Carbon and oxygen stable isotope composition of bulk sediment and abundance of Braarudospahaera in ODP Site 122-762 (Table 1) Siesser, William G Bralower, Timothy J De Carlo, Eric Heinen 122-762B; 122-762C; Braarudosphaera spp.; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Epoch; Event label; Isotope ratio mass spectrometry; Joides Resolution; Leg122; Nannofossil zone; Nannofossil Zone; Martini, 1971; Ocean Drilling Program; ODP; Sample code/label; South Indian Ridge, South Indian Ocean; δ13C, carbonate; δ18O, carbonate Nannofossil assemblages enriched in Braarudosphaera occur in lower Oligocene to lower Miocene sediments at Ocean Drilling Program Sites 762 and 763 on the central Exmouth Plateau. Braarudosphaerids appear here rather abruptly in the lower Oligocene (in Zone NP21). They reach their greatest numbers in the lower Oligocene (in Zones NP22 and NP23), where they comprise up to 10% of some samples. Braarudosphaera bigelowii is the overwhelmingly dominant species, occurring together with rare specimens of B. discula and Micrantholithus pinguis. The holococcoliths Peritrachelina joidesa and Lantemithus minutus are also associated with the Braarudosphaera enrichment. There are two populations of B. bigelowii: one of normal size (10-14 µm) and one of large specimens (20-22 µm). The larger braarudosphaerids are more common than the smaller forms. Braarudosphaera-rich sediments are absent at Wombat Plateau sites during the same time interval. We attribute this to latitudinal control, because the Wombat sites are about 4° north of the central Exmouth Plateau sites. We believe that the occurrence of braarudosphaerids is related to an Oligocene to early Miocene oceanographic event on the Exmouth Plateau. We suspect that mid-ocean up welling of cool, low-salinity, nutrient-rich water along a divergent zone created the Braarudosphaera-nch sediments in the South Atlantic and Indian oceans. |
| title | Carbon and oxygen stable isotope composition of bulk sediment and abundance of Braarudospahaera in ODP Site 122-762 (Table 1) |
| topic | 122-762B; 122-762C; Braarudosphaera spp.; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Epoch; Event label; Isotope ratio mass spectrometry; Joides Resolution; Leg122; Nannofossil zone; Nannofossil Zone; Martini, 1971; Ocean Drilling Program; ODP; Sample code/label; South Indian Ridge, South Indian Ocean; δ13C, carbonate; δ18O, carbonate |
| url | https://doi.org/10.1594/PANGAEA.729251 |