地質記録から古海域の広がりを見積る

抄録

The size of ancient seaway can be estimated from paleo-wave conditions reconstructed from wave ripples and other sedimentary rock records. Possible combinations of wind speed, fetch and length of wave decay are obtained for a given paleo-wave condition by making a reverse use of wave forecasting and swell forecasting methods. This method is unique in that it pays regard to the process of wave decay. The calculated possible fetches fall into a certain range. The maximum value of calculated fetch is that for fully developed waves having no chance to decay. The range of fetches can be reduced using some sedimentological criteria, e. g. storm/fair weather sedimentation. Reference to present-day ocean waves further provides a basis for omitting unrealistic fetch lengths. Estimated fetch and decay lengths place some constraint on the minimum size of the paleo-seaway.