Calcareous nannofossil biostratigraphy of the Nankai Trough

Abstract

ODP Leg 131 recovered nannofossil-bearing sediments from Site 808 in the Nankai Trough, western Pacific Ocean. Three holes were examined for nannofossils, 808A, 808B and 808C. A total of 22 nannofossil events were recognized, of which 10 are used as zonal markers. Age estimates provided by nannofossils show that the sedimentation rate in the trench-fill deposits of the Nankai Trough was very high, 800-1350 m/m.y. (0-0.46 Ma), whereas in the Shikoku Basin deposits (>0.46 Ma), the sedimentation rate was much lower (24-200 m/m.y.). These age estimates also provide an extrapolated age of approximately 15 Ma for the basaltic basement at Site 808. -from Author