Time-Progressive Morphometric Changes of the Genus Gephyrocapsa in the Quaternary Sequence of the Tropical Indian Ocean, Site 709

Matsuoka, Hiromi; Okada, Hisatake

doi:10.2973/odp.proc.sr.115.155.1991

Cited by 32 publications

(89 citation statements)

References 11 publications

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“…The classification of Gephyrocapsa in this study closely follows the one proposed by Matsuoka and Okada (1990). They identified two groups of Gephyrocapsa: small Gephyrocapsa, which consist of small specimens with relatively large central openings; and large Gephyrocapsa, which consist of large specimens with relatively small central openings.…”

Section: Classification Of Gephyrocapsamentioning

confidence: 71%

“…A with slits on the distal shield and Gephyrocapsa spp. (small) without slits on the distal shield, were recognized in the small Gephyrocapsa complex by Matsuoka and Okada (1990). In addition to these two taxa, Gephyrocapsa ornata var.…”

Section: Classification Of Gephyrocapsamentioning

confidence: 99%

“…A near the Brunhes/Matuyama boundary. Matsuoka and Okada (1990) also reported morphometric changes of the genus Gephyrocapsa in the Quaternary sequence cored at Site 709 in the equatorial Indian Ocean. They identified three development cycles of the large morphotype of Gephyrocapsa (1.6-1.1,0.9-0.5, and 0.5 Ma to the present).…”

Section: Introductionmentioning

confidence: 99%

“…This dominance interval correlates with the acme of G. protohuxleyi var. A in the Mariana core (KH82-4 st. 21) documented by Matsuoka and Okada (1989). Gartner's (1977) zonal scheme documented abundance peaks of small Gephyrocapsa in the middle Quaternary and named the interval "small Gephyrocapsa Zone."…”

Section: Abundance Patterns Of Small Gephyrocapsamentioning

confidence: 99%

“…3). Matsuoka and Okada (1990) further divided the large Gephyrocapsa into four subspecies {Gephyrocapsa sp. A, Gephyrocapsa sp.…”

Section: Classification Of Gephyrocapsamentioning

confidence: 99%

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Morphometric Changes of the Genus Gephyrocapsa at Site 790, Subtropical Pacific Ocean

Matsuoka¹,

Fujioka²

1992

Proceedings of the Ocean Drilling Program

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Cyclic changes in the morphometry of large specimens of the calcareous nannofossil genus Gephyrocapsa, first discovered in the Indian Ocean, are recognized in the middle Quaternary sedimentary sequence of Site 790 drilled in the Izu-Bonin forearc. The second and a part of the third cycle of morphometric development of large Gephyrocapsa were identified at this site. Small Gephyrocapsa (in particular, Gephyrocapsa protohuxleyi var. A and Gephyrocapsa ornata var. A) generally compose approximately 50% of the middle Quaternary nannoflora. Four abundance peaks of the small Gephyrocapsa complex were seen in this middle Quaternary sequence, three of which were not seen in previously studied Indian Ocean or Mariana Arc cores.

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Section: Classification Of Gephyrocapsamentioning

confidence: 71%

Section: Classification Of Gephyrocapsamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Abundance Patterns Of Small Gephyrocapsamentioning

confidence: 99%

“…3). Matsuoka and Okada (1990) further divided the large Gephyrocapsa into four subspecies {Gephyrocapsa sp. A, Gephyrocapsa sp.…”

Section: Classification Of Gephyrocapsamentioning

confidence: 99%

See 3 more Smart Citations

Morphometric Changes of the Genus Gephyrocapsa at Site 790, Subtropical Pacific Ocean

Matsuoka¹,

Fujioka²

1992

Proceedings of the Ocean Drilling Program

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Plio‐Pleistocene palaeoceanography of the tropical Indian Ocean (ODP Hole 709C): Radiolarian and CaCO₃ evidence

Haslett

Funnell

Dunn

et al. 1994

J Quaternary Science

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Sediments spanning the Olduvai subchron (1.79-1.95 Ma) of ODP Hole 709C in the tropical Indian Ocean were sampled at 5-cm intervals. High-resolution quantitative radiolarian and CaC03% data have been used as proxies in interpreting palaeoceanographical conditions, and a comparison made with previously obtained oxygen isotope data. Radiolarian data were subjected to principal components analysis, resulting in four varimax factors. Factor 1 accounted for the greatest variation and comprised well-known warm-water and cold-water taxa, with high +ve and -ve scores respectively, which were used in the construction of a temperature index. Results indicate a tripartite temporal division of Olduvai palaeoceanography. In the early Olduvai, prior to 1.895 Ma, and the late Olduvai, approximating the Plio-Pleistocene boundary at 1.81 Ma, divergence-driven equatorial upwelling and high-productivity coincide with isotope-defined 'interglacials', and with generally low CaC03%. However, during the mid-Olduvai, upwelling, productivity and sedimentation rates were all reduced. These changes in palaeoceanography are thought to be linked directly to eccentricity modulated variations in the precession of the Earth's orbit. The early and late Olduvai coincide with periods of minimum eccentricity, when precessional reinforcement of the southwest monsoon is weakest, coastal upwelling along the Oman margin is reduced, and zonal wind-driven equatorial divergence upwelling is increased. The mid-Olduvai, however, corresponds with an eccentricity maximum, during which monsoonal activity is stronger and equatorial divergence upwelling weak. bourM~ of Q~~~~~~~~~

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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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Time-Progressive Morphometric Changes of the Genus Gephyrocapsa in the Quaternary Sequence of the Tropical Indian Ocean, Site 709

Cited by 32 publications

References 11 publications

Morphometric Changes of the Genus Gephyrocapsa at Site 790, Subtropical Pacific Ocean

Morphometric Changes of the Genus Gephyrocapsa at Site 790, Subtropical Pacific Ocean

Plio‐Pleistocene palaeoceanography of the tropical Indian Ocean (ODP Hole 709C): Radiolarian and CaCO₃ evidence

Species level variation in coccolithophores

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Time-Progressive Morphometric Changes of the Genus Gephyrocapsa in the Quaternary Sequence of the Tropical Indian Ocean, Site 709

Cited by 32 publications

References 11 publications

Morphometric Changes of the Genus Gephyrocapsa at Site 790, Subtropical Pacific Ocean

Morphometric Changes of the Genus Gephyrocapsa at Site 790, Subtropical Pacific Ocean

Plio‐Pleistocene palaeoceanography of the tropical Indian Ocean (ODP Hole 709C): Radiolarian and CaCO3 evidence

Species level variation in coccolithophores

Contact Info

Product

Resources

About

Plio‐Pleistocene palaeoceanography of the tropical Indian Ocean (ODP Hole 709C): Radiolarian and CaCO₃ evidence