(Table 2) Distribution of phytoliths in selected samples from DSDP Site 90-591

Phytoliths are described from deep sea sediments at Site 591 in the southwestern Pacific. Their regional distribution is related to the arid and semiarid regions of Australia, from where they were blown by westerly winds into the Tasman Sea area. The stratigraphic record ranges from the middle Miocene, at about 14.4 m.y., until the early Pleistocene. A distinct increase in frequencies observed during the Pliocene and a maximum at about 2.5 m.y. coincide with important trends in paleogeography and paleoclimatology: the development of the Antarctic ice cap, the northward drift of the Australian Plate, and the generation of arid conditions on the Australian continent.植硅体（Phytoliths）的研究对象为西南太平洋591站位的深海沉积物。其区域分布与澳大利亚干旱、半干旱区域密切相关，植硅体正是从这些区域经西风带吹扬后进入塔斯曼海海域。本次研究涉及的地层记录年代跨度为中中新世（约1440万年前）至早更新世。观测显示，植硅体丰度在上新世出现显著上升，并在约250万年前达到峰值，这一变化与古地理学、古气候学的重要演化趋势高度吻合：包括南极冰盖的形成、澳大利亚板块向北漂移，以及澳大利亚大陆干旱环境的形成。