1,099 research outputs found
Part of the global seawater delta oxygen-18 database from reference Ganssen 1991
No full textPosition was read off a graph
Hydrography and plankton abundance of horizontal plankton hauls sampled off Northwest Africa (Table 1b)
No full textHydrography and plankton abundance of horizontal plankton hauls sampled off Northwest Africa (Table 1b
Hydrography and plankton abundance of vertical plankton haul profile GIK15658-2, off NW Africa (Table 1c)
No full textHydrography and plankton abundance of vertical plankton haul profile GIK15658-2, off NW Africa (Table 1c
Hydrography and plankton abundance of vertical plankton haul profile GIK15679-2, off NW Africa (Table 1c)
No full textHydrography and plankton abundance of vertical plankton haul profile GIK15666-8, off NW Africa (Table 1c
Stable isotopic measurement on planktonic foraminifera of vertical plankton haul samples GIK15666-8, off NW Africa (Table 1d)
No full textStable isotopic measurement on planktonic foraminifera of vertical plankton haul samples GIK15679-2, off NW Africa (Table 1d
Stable isotopic measurements on planktonic foraminifera of plankton haul samples off Northwest Africa (Table 1d)
No full textStable isotopic measurements on planktonic foraminifera of plankton haul samples off Northwest Africa (Table 1d
Controls on planktonic foraminifera apparent calcification depths for the northern equatorial Indian Ocean
No full textWithin the world’s oceans, regionally distinct ecological niches develop due to differences in water temperature, nutrients, food availability, predation and light intensity. This results in differences in the vertical dispersion of planktonic foraminifera on the global scale. Understanding the controls on these modern-day distributions is important when using these organisms for paleoceanographic reconstructions. As such, this study constrains modern depth habitats for the northern equatorial Indian Ocean, for 14 planktonic foraminiferal species (G. ruber, G. elongatus, G. pyramidalis, G. rubescens, T. sacculifer, G. siphonifera, G. glutinata, N. dutertrei, G. bulloides, G. ungulata, P. obliquiloculata, G. menardii, G. hexagonus, G. scitula) using stable isotopic signatures (δ18O and δ13C) and Mg/Ca ratios. We evaluate two aspects of inferred depth habitats: (1) the significance of the apparent calcification depth (ACD) calculation method/equations and (2) regional species-specific ACD controls. Through a comparison with five global, (sub)tropical studies we found the choice of applied equation and δ18Osw significant and an important consideration when comparing with the published literature. The ACDs of the surface mixed layer and thermocline species show a tight clustering between 73–109 m water depth coinciding with the deep chlorophyll maximum (DCM). Furthermore, the ACDs for the sub-thermocline species are positioned relative to secondary peaks in the local primary production. We surmise that food source plays a key role in the relative living depths for the majority of the investigated planktonic foraminifera within this oligotrophic environment of the Maldives and elsewhere in the tropical oceans
Portrait of President Gerald Ford.
No full textHandwritten Inscription: \u27To Felton M. Johnston - best always, Gerald Ford\u27https://egrove.olemiss.edu/fmjohnston/1097/thumbnail.jp
(Table 2) Oxygen and carbon isotope composition of planktonic foraminiferal species from DSDP Holes 93-603B and 93-604, and one benthic species from Hole 93-604
No full textHoles 603C and 604 of DSDP Leg 93 were drilled on the western Atlantic continental rise at water depths of 4633 m and 2364 m, respectively. In Hole 603C, a nearly continuous, undisturbed, and complete section of Pliocene and lower Pleistocene sediments was recovered by hydraulic piston coring; in Hole 604, a section of uppermost Miocene to Pleistocene sediments was incompletely recovered by rotary coring.
In order to reconstruct the Pliocene and Pleistocene history of isotopic variations, 139 oxygen and carbon isotope values were determined for planktonic and monospecific benthic foraminifer samples from these holes. Large parts of the Pleistocene history could not, however, be documented because sample intervals were large and sediments at Site 604 were redeposited. Time correlation is based on magnetostratigraphic (Hole 603C) and micropaleontologic (Hole 603C, Site 604) interpretation.
Stable isotope analyses were carried out on the planktonic foraminiferal species Globigerinoides ruber, G. obliquus, and Globorotalia inflata from Hole 603C (48 analyses) and from Site 604 (48 analyses); at Site 604, the benthic foraminifer Uvigerina peregrina (43 analyses) was also studied through the section. Age calibration for Hole 603C is based on the magnetostratigraphy of Canninga et al. (1987; doi:10.2973/dsdp.proc.93.130.1987), which uses the time scale of Lowrie and Alvarez (1981)
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