Ravelo, Ana Christina; Shackleton, Nicholas J (1995): Stable carbon and oxygen isotope record of planktonic foraminifera in ODP Site 138-851 [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.807757, Supplement to: Ravelo, AC; Shackleton, NJ (1995): Evidence for surface-water circulation changes at Site 851 in the eastern Tropical Pacific Ocean. In: Pisias, NG; Mayer, LA; Janecek, TR; Palmer-Julson, A; van Andel, TH (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 138, 503-514, https://doi.org/10.2973/odp.proc.sr.138.126.1995
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Abstract:
This study investigates changes in the upper water column hydrography at Site 851 of the eastern tropical Pacific Ocean since the late Pliocene, using the oxygen and carbon isotopic composition of three species of planktonic foraminifers, each calcifying at different depths in the photic zone. The upper ocean seasonal hydrography in this region responds to the seasonally changing trade winds and thus is expected to respond to past changes in trade winds. One major change occurs at about 1.5 Ma, when the thermocline adjusts from a deep position to a shallower position. The thermocline remains in a relatively shallow position throughout the record up to recent time, with slight variations occurring synchronously with glacial/interglacial stages. In glacials, SSTs are probably a few degrees cooler and the thermocline is slightly deeper. From our knowledge of seasonal and interannual adjustments of the thermocline in this location, a deeper thermocline might be interpreted as either a decrease in the strength of the Equatorial Undercurrent (EUC) that results from lower mean wind strength or an increase in the Equatorial Countercurrent (ECC), which results from an increase in the strength of the southeasterly trade winds. A major shift from higher to lower carbon isotope values occurred at about 1.9 Ma, marking a transition to reduced planktonic-benthic d13C differences after 1.9 Ma. The carbon isotopic data indicate that changes in the carbon isotopic composition of intermediate upwelling water occurs at higher frequencies than the glacial/interglacial changes in ice volume.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 0.637236 * Median Longitude: -95.260013 * South-bound Latitude: -9.550000 * West-bound Longitude: -179.400000 * North-bound Latitude: 2.770283 * East-bound Longitude: 6.050000
Date/Time Start: 1965-03-18T00:00:00 * Date/Time End: 1991-06-21T00:00:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
2 datasets
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Datasets listed in this publication series
- Ravelo, AC; Shackleton, NJ (1995): (Table 1) Stable carbon and oxygen isotope ratios of planktonic foraminifera from ODP Site 138-851. https://doi.org/10.1594/PANGAEA.807744
- Ravelo, AC; Shackleton, NJ (1995): (Table 2) Comparison of core-top stable oxygen isotope values from tropical sites. https://doi.org/10.1594/PANGAEA.807756