Overlapping ODP Holes 1179B and 1179C in the northwest Pacific Ocean between Japan and Shatsky Rise yielded a near-continuous, 221.5-m-thick upper Miocene to Pleistocene diatom record in an expanded section (sedimentation rate = 29.29 m/m.y.) with 98.8% recovery. Due to the presence of diatom species included in both low-latitude and high-latitude biostratigraphies, zonations for the equatorial Pacific and northwest Pacific were applied to these sediments. The oldest zones from each zonation are the N. miocenica Zone and the R. californica Zone, respectively. Only one zonal boundary is not present, that being the top of the N. jouseae Zone and base of the R. praebergonii Subzone A (equatorial Pacific). Overall preservation is good, and sample abundances vary from rare to abundant. No samples were barren of diatoms.
The entire section was apparently deposited below the calcite compensation depth; thus, little useful planktonic calcareous biostratigraphic information was obtained. However, the combined section did yield an excellent paleomagnetic record along with palynomorph, agglutinated foraminiferal, and radiolarian biostratigraphies. The palynomorph record extends down to Sample 191-1179C-11H-CC (143.84 mbsf), which is of late early Pliocene age, whereas the radiolarian record parallels the diatom record (Shipboard Scientific Party, 2001).
Therefore, when the diatom data presented here are combined with the other microfossil and paleomagnetic records, this section at Site 1179 should be a valuable addition to the drill core archives used to study the late Neogene paleoclimatic and paleoceanographic history of the northwest Pacific Ocean.