Distribution of diatoms in Oligocene to Pleistocene sediments of the tropical Pacific

According to the drilling probes of the Deep Waier Drilling Project, Neogene sediments in a tropical area of the Pacific Ocean are divided into 15 zones based on diatoms. The author shows that a unique zonation may be applied for the entire region. Identification of diatoms zones boundaries was conducted through their direct correlation with nannoplancton, radiolarian and foraminiferal zonal sceals. Their ultra-structure and morphological relationship are being analysed. The mode of siliceous accumulation within the equatorial belt differed through the western central and eastern region since the early Miocene and the difference become more evident from the end of Middle Miocene. The distribution of Neogene diatomaceous silt in the tropical area is controlled by the character of gyre-water circulation and agrees with the modern geographical zonation.

根据深海钻探计划（Deep Waier Drilling Project）的钻探取样数据，太平洋热带海区的新近纪（Neogene）沉积物可依据硅藻（diatoms）划分为15个分带。研究证实，一套通用的分带方案可覆盖整个研究区域。硅藻带边界的识别通过与超微浮游生物（nanoplankton）、放射虫（radiolarian）及有孔虫（foraminiferal）分带标尺的直接关联比对完成，相关研究对其超微结构与形态学关联展开了分析。自早中新世以来，赤道带内的硅质沉积模式在西、中、东太平洋区域便存在差异，且该差异从中中新世末期开始愈发显著。热带海区新近纪硅藻质粉砂岩的分布受大洋环流系统（gyre-water circulation）特征调控，其分布格局与现代地理分带特征相符。