1999 Fiscal Year Final Research Report Summary
Basic study for reconstruction of submarine-fan models
| Project/Area Number |
09640539
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | Chiba University |
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Principal Investigator |
ITO Makoto Chiba University, 理学部, 教授 (10201930)
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| Project Period (FY) |
1997 – 1999
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| Keywords | submarine fan / sequence model / channel-overbank / sheet-like turbidite / basin floor fan / slope fan |
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| Research Abstract |
Sheet-like turbidite packets and channel-overbank systems are interpreted to be major components of subnarine fans. Spatial and temporal relationships between the two major components, however, are not yet clearly understood, in particular for sand-dominated submarine fans in active-margin basins. Three-dimensional outcrop analysis of an ancient sandy submarine-fan succession in a Late Miocene-Early Pliocene forearc basin on the Boso Peninsula, Japan, together with mapping of chronostratigraphic surface defined by volcanic ash beds, indicates that deposition of sheet-like turbidite packets was intimately associated with the lateral migration of depocenters of channel-overbank systems and distinct entrenchment of fan channels in response to upfan avulsion. Deposition of a sheet-like turbidite packet is not restricted in a single interchannel low, but rather is spread out over most of the channel-overbank area, possibly reflecting the high width/depth ratio of channel-overbank system on sandy submarine fans. Largely contemporaneous deposition of sheet-like turbidite packets and channel-overbank systems further indicates that the "basin-floor fan" and "slope fan" of the sequence-stratigraphic model do not necessarily characterize different parts of a relative seal-level lowstand.
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