36. ASSESSMENT OF DIATOM AND RADIOLARIAN HIGH- AND LOW-LATITUDE ZONATIONS IN NORTHWEST PACIFIC SEDIMENTS: COMPARISON BASED UPON

• Main Authors: Lloyd H. Burckle, J. J. Morley, Lamont-doherty Geological Observatory, I. Koizumi, U. Bleil, Ruhr-universitàt Bochum
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pacific; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.567.3783; http://www.deepseadrilling.org/86/volume/dsdp86_36.pdf

Sediments recovered by the hydraulic piston corer at three northwest Pacific sites (Sites 578, 579, and 580; Fig. 1) have a relatively high accumulation rate (> 30 m/m.y.) and contain a detailed paleomagnetic record. This makes it pos-sible to examine the various biostratigraphic datum levels used in low- and high-latitude siliceous floral/faunal zona-tions in this transitional setting in order to determine which zonal scheme or combination of schemes provides the most reliable biostratigraphic information for the Neogene and Quaternary in this region of the North Pacific. Most high-lat-itude diatom species do not penetrate the equatorial regions, although they do occur in subarctic to transitional and oc-casionally subtropical waters. Significant diachroneity is observed in middle Pleistocene sediments. Long-ranging equa-torial Pacific forms are found in the northwest Pacific and their first and last appearances are usually isochronous with the equatorial record. However, both first and last appearances tend to be diachronous for species that have short ranges in low latitudes. All of the biostratigraphic marker species associated with the North Pacific radiolarian zonation are present in sediments at the three Deep Sea Drilling Project sites with each event synchronous with its counterpart in high-latitude sediments. Therefore, the North Pacific faunal zonation can be reliably applied to siliceous sediments across a broad region of the northwest Pacific extending from the subarctic to intermediate latitudes.