This study investigates the development of oligotrophic conditions, thickening, and zonal and meridional contraction of the West Pacific Warm Pool (WPWP) during the Pliocene. It has been hypothesized that the evolution of the WPWP and the establishment of strong equatorial Pacific zonal gradients are closely related to the narrowing of the Indonesian Gateway (IG) as well as the closure of the Central American Seaway (CAS). However, the timing of the development of these events remains unclear. Here we report Pliocene‐to‐Recent relative abundances of planktic foraminifera at Deep Sea Drilling Project (DSDP) Site 214 in the eastern Indian Ocean and at Ocean Drilling Program (ODP) Site 807, in the western Pacific. A comparison of the abundance of mixed‐layer species (MLS) from both sites indicates a pronounced increase in their population between ~3.15 and 1.6 Ma. There is a contemporaneous decrease in the Globigerinita glutinata population during this time, which together with the MLS data suggest the development of oligotrophic conditions in the western tropical Pacific. Our data suggest that the oligotrophic WPWP, resembling present‐day conditions, developed around 3.15 Ma and was closely linked to the gradual constriction of the IG.

中文翻译：

---

上新世一更新世边界的少营养型西太平洋暖池演化

这项研究调查了上新世期间贫营养条件的发展，增厚以及西太平洋暖池（WPWP）的纬向和子午向收缩。据推测，WPWP的演变和强大的赤道太平洋纬向梯度的建立与印尼门户（IG）的变窄以及中美洲海道（CAS）的关闭密切相关。但是，这些事件的发生时间尚不清楚。在这里，我们报告了印度洋东部深海钻探项目（DSDP）站点214和西太平洋海洋钻探计划（ODP）站点807上新世至最近的板孔有孔虫相对丰度。比较两个地点的混合层物种（MLS）的丰度，表明它们的种群在〜3之间显着增加。15和1.6 Ma。同时减少在此期间，globigerinita glutinata种群与MLS数据一起表明了热带西部太平洋地区的贫营养状况的发展。我们的数据表明，与当前条件类似的贫营养型WPWP在3.15 Ma左右发育，与IG的逐渐收缩密切相关。