2002 Fiscal Year Final Research Report Summary
Comparative sedimentology between greenhouse and icehouse stratigraphic successions
| Project/Area Number |
12640437
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Geology
|
|---|
| Research Institution | Chiba University |
|---|
Principal Investigator |
ITO Makoto Chiba University, Department Earth Sciences, Professor, 理学部, 教授 (10201930)
|
|---|
| Project Period (FY) |
2000 – 2002
|
| Keywords | greenhouse / icehouse / hummocky cross-stratification / storm intensity / tempestite / inner shelf / paleotemperature / Phanerozoic |
|---|
| Research Abstract |
Hummocky cross-stratification is believed to be one of diagnostic sedimentary structures in a storm-dominated shallow marine environment. In general, the wavelength of hummocky cross-stratification increases with the increase in bed thickness of tempesties. Within a tempestie bed, the wavelength of hummocky cross-stratification decreases upsection and this relationship may correspond to the decrease in the orbital diameters during the waning stage of storm waves. Furthermore, paleoflow directions of tempesties, which were investigated on the basis of sole marks, tend to more orthogonal relative to the paleo-shorelines with the increase in bed thickness of tepmestites and this relationship may reflect higher degree of coastal setup in response to the increase in storm intensities. Therefore, the wavelength of hummocky cross-stratification is interpreted to be a function of the orbital diameters of storm-induced oscillatory currents near sea floors and many reflect the intensity of storm
… More
waves. Here I investigated temporal variation in the hummocky cross-stratification wavelength as a proxy for the storm intensity through the Phanerozoic. The hummocky cross-stratification wavelength shows secular changes though the Phanerozoic with two major peaks at middle Cretaceous and late Devonian, together with two other secondary peaks at early Jurassic and late Ordovician. These secular changes largely correspond to major greenhouse-and-icehouse cycles of global environmental changes. The peaks of the hummocky cross-stratification wavelength, however, are earlier or later than major warmer periods of independently estimated long-term fluctuation in the global temperatures. These time lags are interpreted to indicate that the threshold conditions for the intensification of storms occurred at some times before and after the extreme warmth of global temperatures. The outcome of this study suggests that the storm intensity would be the highest before and/or after the maximum stage of the global warming with an ongoing greenhouse phase in future. Less
|
Research Products
(20 results)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
[Publications] Nishikawa,T., and Ito,M.: "Wave and tidal climates in a tidal-inlet environment in the Late Pleistocene paleo-Tokyo Bay, Japan : Implications for dynamic conditions of combined-flow ripples, In Park,Y.A., and Davis,R.A., eds., TIDALITE 2000"Journal of The Korean Society of Oceanography. Special Publication. 77-86 (2001)
Description
「研究成果報告書概要(欧文)」より
-
-
[Publications] Ito,M.: "Kuroshio-Current-influenced sandy contourites from the Plio-Pleistocene Kazusa forearc basin, Boso Peninsula, Japan, In Stow, D.A.V., Pudsey,C.J., Howe,J.A., Faugress,J.-C, and Vina,A.R., eds., Deep-water contourite systems Modern drifts and ancient series, seismic and sedimentary characteristics"Geological Society of London, Memoirs. 22. 421-432 (2002)
Description
「研究成果報告書概要(欧文)」より
-
