Stratigraphy and isotropic record of the middle Kazusa group, Boso peninsula, S.E. Japan
Glacio-eustasy is a primary control on sedimentation patterns in the open ocean and along passive continental margins, but the relative importance of glacio-eustasy, sediment supply and tectonic uplift/subsidence in clastic-dominated sections formed at active plate margins remains poorly understood....
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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UCL (University College London)
1996
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| Online Access: | https://discovery.ucl.ac.uk/id/eprint/10100652/1/Stratigraphy_and_isotropic_rec.pdf https://discovery.ucl.ac.uk/id/eprint/10100652/ |
| Summary: | Glacio-eustasy is a primary control on sedimentation patterns in the open ocean and along passive continental margins, but the relative importance of glacio-eustasy, sediment supply and tectonic uplift/subsidence in clastic-dominated sections formed at active plate margins remains poorly understood. This study involved detailed sedimentary logging and the construction of a high-resolution δ 18O and δ13C record from the planktonic foraminifera, Glohorotalia inflata, for sediments in the Plio- Pleistocene Kazusa Group, a forearc basin fill from onland SE Japan. Globally recognised glacial and interglacial events, stage 34 to stage 16 are identified in the isotopic results, which correspond to an age range from 1.18 - 0.6 Ma. There is a good positive correlation between the presence of sandstone packets and inferred glacial intervals, suggesting that relative sea level changes during glacial- interglacial cycles exerted the primary control on sediment accumulation in the deep- marine forearc basin. The overall regressive nature of the middle Kazusa Group is interpreted as the result of a third-order stratigraphic cyclicity controlled by the subsidence history of the Kazusa forearc basin. Superimposed on the third-order stratigraphic cyclicity is a higher frequency fourth- and fifth-order cyclicity produced by perturbations in the Earth's orbit resulting in fluctuations in global ice volume. Cross-spectral analysis of the Kazusa Group suggests that throughout the period of deposition of the middle Kazusa Group the dominant orbital parameter was the 23 kyr precessional component followed by the 41 kyr cycle. The introduction of the 100 kyr component occurred later at, ca. 875 kyrs. |
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