A preliminary study on diatoms and silicoflagellates in cores from CC Zone, the East Pacific

After analyzing the diatoms and silicoflagellates in the 1787 of east area and the 2437 of west area from CC Zone, the East Pacific, 31 genus and 81 species and varieties of diatom and 7 genus and 12 species of silicoflagellates are identified. There are 8 diatom zones in Core 1787 and 1 diatom Zone in Core 2437. According to the characteristics of diatom zones and the occurring and extinct ages of some diatom and silicoflagellate species, the strata since Oligocene in the region are subdivided. Lastly, com-bined with the data of radiolarians and paleomagnetism, some problems for Core 1787 are discussed, including where is the lower boundary of Quaternary, whether Pliocene is absent or not and whether Oligocene is present or not.