11:15 AM - 11:30 AM
[MIS08-09] Proposal of Deep Sea Drilling for the Jurassic/Cretaceous boundary in the western Pacific
Keywords:Jurassaic/Cretaceous boundary, GSSP, Deep Sea Drilling, Radiolarian biostratigraphy
Pelagic radiolarian-rich sequences across the JKB have been reported in ODP/IODP sites in the western Pacific. The most complete section encompassing the JKB is recorded at ODP Leg 129 Site 801 in the central Pigafetta Basin, western Pacific. Unfortunately, the recovery of cores at the site was too poor to clarify the evolutionary lineages of radiolarians. Extremely well-preserved radiolarian fossils together with minor calcareous nannofossils of early Berriasian age were obtained from the outer slope of the Mariana Trench by a dive of “Shinkai 6500” in 1993. The rock sample is not a chert but a tuffaceous clayey radiolarite which contains as many as 400 species of radiolarian shells with opal-A phase. A sequence suitable for radiolarian biostratigraphy around the Jurassic-Cretaceous transition is expected to lie under the deep sea near the Mariana Trench. Deep sea drilling nearby the dive site can contribute to gathering crucial data for selecting the GSSP of the JKB.