(Table 2) Relative abundance of planktonic foraminifera species in Pliocene - Early Quaternary sediments from ODP Hole 111-677A

Planktonic foraminifera from Pliocene - Early Quaternary sediments of ODP Hole 111-677A were studied in detail. It was shown that the majority of detected zonal taxa are reliable biostratigraphic reference points. Between 30 and 210 m in the core zones of planktonic foraminifera from PL1b to Pt1 (according to the W.A. Berggren scale) were distinguished. Changes of planktonic foraminifera complexes from sediments of Hole 111-677A are closely associated with climate-controlled development of surface water masses of the Eastern Equatorial Pacific during 4.6-0.65 million years ago. Sharp decrease in equatorial-tropical species about 3.4 million years ago correlated with cessation of surface water exchange between tropical regions of the Pacific and Atlantic oceans due to formation of the Central American isthmus. The paleotemperature method of M.S Barash was used for reconstructing surface temperatures. Maximum temperatures were reconstructed in late Early Pliocene (26.4°C) and in Late Pliocene (26.6°C) and minimum ones - in the beginning of Early Pliocene (18.4°C), in the middle of Late Pliocene (19.6°C). Cold events occurred: 4.6-4.3, 2.8-2.5, and 1.7-1.2 million years ago, and warm: 4.3, 4.18-3.4, 2.5-2.3, and 1 million years ago. In general, the middle of Early Pliocene, the middle of late Pliocene and early Pleistocene are characterized by cold-water conditions, and the end of Early and the end of Late Pliocene - by warm-water conditions.

对大洋钻探计划（Ocean Drilling Program, ODP）111-677A钻孔上新世-早更新世沉积物中的浮游有孔虫（Planktonic foraminifera）开展了详细研究。研究表明，多数检出的分带类群均为可靠的生物地层学参考点位。在岩心30~210米深度区间内，依据W.A.伯格格林（W.A. Berggren）的划分方案，识别出了从PL1b至Pt1的浮游有孔虫分带序列。111-677A钻孔沉积物中浮游有孔虫组合的演替，与4.6~0.65百万年前东赤道太平洋表层水团受气候调控的演化过程密切相关。约3.4百万年前赤道-热带属种的急剧减少，与中美洲地峡形成后太平洋与大西洋热带区域表层水交换停滞存在显著关联。本次研究采用M.S.巴拉什（M.S Barash）的古温度方法重建表层海水温度：早上新世晚期（26.4℃）与上新世晚期（26.6℃）达到温度峰值，早上新世初期（18.4℃）、上新世晚期中期（19.6℃）则为温度谷值。研究识别出多期冷事件与暖事件：冷事件发生于4.6~4.3、2.8~2.5及1.7~1.2百万年前；暖事件发生于4.3、4.18~3.4、2.5~2.3及1百万年前。总体而言，早上新世中期、上新世晚期中期及早更新世以冷水环境为特征，而早上新世末期与上新世末期则对应暖水环境。