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Siesser, William G; Bralower, Timothy J; De Carlo, Eric Heinen (1992): Carbon and oxygen stable isotope composition of bulk sediment and abundance of Braarudospahaera in ODP Site 122-762 (Table 1) [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.729251, Supplement to: Siesser, WG et al. (1992): Mid-Tertiary Braarudosphaera-rich sediments on the Exmouth Plateau. In: von Rad, U; Haq, BU; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 122, 653-663, https://doi.org/10.2973/odp.proc.sr.122.163.1992

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Abstract:
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.
Project(s):
Coverage:
Latitude: -19.887000 * Longitude: 112.254000
Date/Time Start: 1988-07-26T11:00:00 * Date/Time End: 1988-08-05T08:30:00
Minimum Elevation: -1371.0 m * Maximum Elevation: -1371.0 m
Event(s):
122-762B * Latitude: -19.887000 * Longitude: 112.254000 * Date/Time Start: 1988-07-26T11:00:00 * Date/Time End: 1988-07-27T03:25:00 * Elevation: -1371.0 m * Penetration: 175.4 m * Recovery: 174.9 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg122 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 19 cores; 175.4 m cored; 0 m drilled; 99.7 % recovery
122-762C * Latitude: -19.887000 * Longitude: 112.254000 * Date/Time Start: 1988-07-27T03:25:00 * Date/Time End: 1988-08-05T08:30:00 * Elevation: -1371.0 m * Penetration: 940 m * Recovery: 534.54 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg122 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 91 core; 940 m cored; 0 m drilled; 56.9 % recovery
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1Event labelEvent
2Sample code/labelSample labelSiesser, William GDSDP/ODP/IODP sample designation
3δ13C, carbonateδ13C carb‰ PDBSiesser, William GIsotope ratio mass spectrometry
4δ18O, carbonateδ18O carb‰ PDBSiesser, William GIsotope ratio mass spectrometry
5Braarudosphaera spp.Braarudosphaera spp.Siesser, William G
6EpochEpochSiesser, William G
7Nannofossil zoneNannos zoneSiesser, William GNannofossil Zone; Martini, 1971
Size:
54 data points

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