Quaternary Nannofossils from Goban Spur, Eastern North Atlantic Ocean, Deep Sea Drilling Project Holes 548 and 549A

Pujos, A.

doi:10.2973/dsdp.proc.80.129.1985

Cited by 11 publications

(9 citation statements)

References 12 publications

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“…In other parts of the world, reported LOD's for H. sellii are 1.22 Ma in the North Atlantic (Pujos, 1985a), 1.10-1.27 Ma at six DSDP Leg 94 drill sites in the North Atlantic (Takayama and Sato, 1986), 1.22 Ma in the equatorial Pacific (Gartner, 1977), 1.23 Ma in the central equatorial Pacific (Pujos, 1985a), and 1.20 Ma in the subtropical northwestern Pacific Ocean (Matsuoka and Okada, 1989). Backman and Shackleton (1983) questioned whether the 1.37 Ma disappearance of//, sellii might be due to selective dissolution and concluded that dissolution did not effect this datum.…”

Section: Stratigraphic Standardsmentioning

confidence: 99%

“…This is partly due to the criteria (i.e., angle of bridge, shield roundness, size of central opening, rim width, and number of shield elements) some workers have used to split this genus at the species level using electron microscopy (Sambtleben, 1980;Pujos-Lamy, 1977;Pujos, 1985b;Matsuoka andOkada, 1989 andand others). Compounding this problem is the small size of the gephyrocapsids, which makes identification difficult at the species level in light microscope studies.…”

Section: Stratigraphic Standardsmentioning

confidence: 99%

See 1 more Smart Citation

Calcareous Nannofossil Biostratigraphy from the Japan Sea, Sites 798 and 799: Evidence for an Oscillating Pleistocene Oceanographic Frontal Boundary

Muza¹

1992

Proceedings of the Ocean Drilling Program

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Preliminary results of the biostratigraphic analysis of calcareous nannofossils recovered from Ocean Drilling Program Leg 128, Sites 798 and 799, provide clues to the Quaternary oceanography of the Japan Sea. The distribution of calcareous nannofossils from the Quaternary sediments at Site 798 (903 m water depth) may record the position of an Oceanographic frontal boundary between warm water derived from a branch of the Kuroshio Current as it entered the Japan Sea through the Tsushima Straits to the south, and colder water introduced into the western portion of the Japan Sea derived from the winter chilling of northern Japan Sea surface waters. This Oceanographic front probably oscillated north-south over Site 798 in response to glacial/interglacial cycles, or perhaps to some other climatic event or combination of events unique to the Japan Sea. During the last 1.5 m.y., six major intervals are recognized when the Oceanographic front may have been north of Site 798 separated by five major intervals when the frontal boundary may have been south of the site. These migrations were centered around approximately 0.125, 0.29, 0.56, 0.62, 0.85, 0.91, 0.98, 1.0, 1.11, and 1.5 Ma, which correspond to the boundaries separating nannofossil-rich sediments from barren or nearly barren, low-carbonate intervals. Nannofossil-rich intervals may represent times when the frontal boundary was north of Site 798, and the site was above the CCD. Barren or nearly barren intervals represent times when the frontal boundary may have been south of Site 798 and the CCD was probably higher. The distribution of calcareous nannofossils at Site 799 (2073 m water depth) appears to be controlled more by the depth of the CCD than by any climatic effects.The FOD (first occurrence datum) of Emiliania huxleyi, the LOD (last occurrence datum) of Psuedoemiliania lacunosa, Helicosphaera sellii, Calcidiscus macintyrei (10 µm), and the FOD and LOD of Reticulofenestra asanoi are recognized from Site 798 cores. The LOD of P. lacunosa is observed in sediments from Site 799.Only in the sediments younger than 1.5 Ma are the nannofossils from Sites 798 and 799 preserved well enough and sufficiently numerous for age dating and paleoceanographic conjecture. In-situ dissolution in older sediments at both sites precludes any dating or paleoenvironmental interpretations.

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Section: Stratigraphic Standardsmentioning

confidence: 99%

Section: Stratigraphic Standardsmentioning

confidence: 99%

Calcareous Nannofossil Biostratigraphy from the Japan Sea, Sites 798 and 799: Evidence for an Oscillating Pleistocene Oceanographic Frontal Boundary

Muza¹

1992

Proceedings of the Ocean Drilling Program

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“…Thus, there are many extant and extinct species classified under the genus Gephyrocapsa, and most of which are defined solely by morphologic characters (e.g. Pujos 1985). According to this taxonomy the modern Gephyrocapsa assemblage consists of four species with first appearances between 1-3.5 Ma (Samtleben 1980;Matsuoka and Okada 1990;Young 1991).…”

Section: Gephyrocapsa Oceanica and Related Species (Plate 5)mentioning

confidence: 99%

Species level variation in coccolithophores

et al. 2004

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Coccolithophores are an ideal test group for investigating fine-scale differentiation within the phytoplankton since their taxonomy is rather well-documented and their biomineralised periplasts -the coccoliths -provide a rich suite of qualitative and quantitative morphological characters and a uniquely extensive fossil record. In addition, extant coccolithophore species can be grown in culture and hence are available for studies of morphological variability under controlled conditions, molecular genetic studies and cytological research.For the CODENET project the following extant species with seemingly global occurrence and spanning the biodiversity of coccolithophores were selected: Coccolithus pelagicus, Calcidiscus leptoporus, Umbilicosphaera sibogae, Syracosphaera pulchra, Gephyrocapsa oceanica, and Helicosphaera carteri. These were used as case studies to elucidate their species level biodiversity. The key merit of our approach was the use of multiple, independent lines of evidence, so as to remove the ambiguity implicit in any one type of study. In each case morphotypes of previously uncertain significance have been shown to represent discrete genotypes and probably well-separated species, with divergence times ranging 314 Geisen et al. from about 100 kyrs to >10 myrs. The evolutionary significance of these results is discussed.

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“…Quaternary deposits from the high-productivity area of the central equatorial Pacific were investigated by Pujos (1985a) for their nannofossil content. This semiquantitative study was mainly biostratigraphically oriented, and it is difficult to use the data for ecologic interpretations.…”

Section: Comparison With Previous Results From the Pacific Ocean And mentioning

confidence: 99%

“…The taxonomy of the Pleistocene reticulofenestrids has been discussed by various workers (Pujos, 1985a(Pujos, , 1985bTakayama and Sato, 1987;Matsuoka and Okada, 1989). For the present study, specimens of the genus Reticulofenestra were subdivided as follows:…”

Section: Reticulofenestrid Groupmentioning

confidence: 99%

Quantitative Nannofossil Biostratigraphy of Quaternary Sequences from Guyots in the Central and Western Pacific Ocean

Erba¹

1995

Proceedings of the Ocean Drilling Program, 144 Scientific Results

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Quantitative analysis of calcareous nannofossils was performed on Quaternary sediments recovered during Leg 144 at Sites 880 (Takuyo-Daisan Guyot), 871 (Limalok Guyot), 872 (Lo-En Guyot), and 873 (Wodejebato Guyot). For each sample, at least 500 specimens were counted with the light microscope and the relative abundance of taxa was computed as percentages. Calcareous nannofloras are very abundant and well preserved. Assemblages are dominated by the gephyrocapsid group, which was subdivided using a simplified taxonomy based on morphologic and morphometric characters that are easily applicable during light microscope investigations. Quantitative analysis of nannofloras revealed distinctive changes in the abundance patterns, especially within the Gephyrocapsa group, at all sites. These events seem to be coeval on a global scale and were used for high-resolution biostratigraphy. Most nannofossil events and biozones previously proposed for the Quaternary were recognized.The sequence recovered at Site 880 is almost complete, but a hiatus was detected in the upper Pleistocene, where the G. oceanica Zone is extremely short. At Site 871, the Quaternary sequence seems to be complete and all the nannofossil events and biozones were detected. Also at Site 872, a complete sequence of nannofossil events was recognized, but the Quaternary section is very thin and suggests very low sedimentation rates and/or the occurrence of minor hiatuses that cannot be determined with biostratigraphy. The spacing of nannofossil events at Sites 800, 871, and 872 is quite different, suggesting variable sedimentation rates and minor gaps caused by the strong currents on top of these guyots. At Site 873, most of the Quaternary is missing; detection of only the lower Pleistocene nannofossil events suggests that the accumulation of recent sediments on Wodejebato Guyot is strongly affected by current activity.Major changes in the composition of Pleistocene nannofloras appear to be coeval on a global scale across a wide latitudinal range within the tropical to equatorial belts. However, the nannofossil records at Sites 871, 872, 873, and 880 indicate that some taxa were locally and temporarily influenced by the specific oceanographic conditions. Further investigations on the distribution of specific taxa, such as the smallest specimens of Gephyrocapsa (2-2.5 µm) and Florisphaera profunda, may help in separating global vs. local/regional effects.

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Quaternary Nannofossils from Goban Spur, Eastern North Atlantic Ocean, Deep Sea Drilling Project Holes 548 and 549A

Cited by 11 publications

References 12 publications

Calcareous Nannofossil Biostratigraphy from the Japan Sea, Sites 798 and 799: Evidence for an Oscillating Pleistocene Oceanographic Frontal Boundary

Calcareous Nannofossil Biostratigraphy from the Japan Sea, Sites 798 and 799: Evidence for an Oscillating Pleistocene Oceanographic Frontal Boundary

Species level variation in coccolithophores

Quantitative Nannofossil Biostratigraphy of Quaternary Sequences from Guyots in the Central and Western Pacific Ocean

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