Miocene planktonic foraminifera from the eastern equatorial Pacific

Neogene calcareous sediments were recovered at 11 sites along two north-south transects in the eastern equatorial Pacific Ocean during Ocean Drilling Program (ODP) Leg 138. An overview of planktonic foraminifer distribution in these sediments was presented in Mayer, Pisias, Janecek, et al. (1992) based on a preliminary examination of core-catcher samples. In general, the preservation state of the foraminifers is poor throughout most of the sedimentary sequences, making this microfossil group here of much less value for biostratigraphy than other microfossil groups. Pliocene-Pleistocene planktonic foraminifers from several sites have been analyzed in great detail for their oxygen and carbon isotope composition in various high-resolution studies (Farrell et al., this volume; Mix et al., this volume; Ravello et al., this volume; Shackleton et al., this volume). Planktonic foraminiferal datums of biostratigraphic value have been identified in several of these studies. This report presents planktonic foraminiferal distribution in selected Miocene sediments.

大洋钻探计划（Ocean Drilling Program, ODP）第138航次期间，研究团队在东赤道太平洋海域的两条南北向断面上的11个站位，采集获取了新近纪钙质沉积物。梅耶（Mayer）、皮西亚斯（Pisias）、雅内克（Janecek）等人（1992）基于对岩芯捕集器样品的初步分析，对该批沉积物中浮游有孔虫（planktonic foraminifer）的分布情况进行了概述。总体而言，绝大多数沉积序列中的有孔虫保存状态不佳，使得该微化石类群在生物地层学研究中的应用价值远低于其他微化石类群。多项高分辨率研究针对多个站位的上新世-更新世浮游有孔虫的氧同位素与碳同位素组成开展了详尽分析（Farrell等，本卷；Mix等，本卷；Ravello等，本卷；Shackleton等，本卷）。上述多项研究已鉴定出若干具备生物地层学研究价值的浮游有孔虫基准面。本报告针对经筛选的中新世沉积物，阐述其中浮游有孔虫的分布情况。