(Table 1) Occurrence of ichthyoliths at DSDP Hole 56-436

Approximately 20 meters of the section near the bottom of Hole 436 was "unfossiliferous," overlain by middle Miocene mudstone with siliceous microfossils and underlain by Cretaceous chert. Therefore we attempt to determine the age of these pelagic clays on the basis of the ichthyoliths. Site 436 is at 39°55.96'N, 145°33.47'E, in a water depth of 5240 meters. The cores investigated here (Nos. 39 and 40) are from 359.5-378 meters below the sea floor. In addition, we studied one sample from Core 41, containing Late Cretaceous radiolarians (436-41-1, 26-31 cm).436号钻孔（Hole 436）底部附近约20米的层段为不含化石的（unfossiliferous）层段，其上覆为含硅质微体化石（siliceous microfossils）的中中新世泥岩，下伏为白垩纪燧石（Cretaceous chert）。因此，本研究尝试基于鱼硬体化石（ichthyoliths）确定这套远洋黏土的形成年代。436站位（Site 436）位于北纬39°55.96′、东经145°33.47′，水深5240米。本次研究所分析的岩芯（编号39与40）取自海底以下359.5~378米的层位。此外，本研究还对41号岩芯（Core 41）中的1件样品进行了分析，该样品编号为436-41-1，层位为26~31厘米，其中含有晚白垩世放射虫（radiolarians）。