Distribution of phytolithes in CRP sediment cores from the Ross Sea, Antarctica

Phytoliths (siliceous plant microfossils) have been recovered from Cenozoic sediments (c. 34 to 17 Ma) in the CRP-2/2A and CRP-3 drillholes cored off Cape Roberts, Victoria Land Basin, Antarctica. The phytolith assemblages are sparse, but well-preserved and dominated by spherical forms similar to those of modern trees or shrubs. Rare phytoliths comparable to modern grass forms are also present. However, due to the paucity of phytolith data, any interpretations made are necessarily tentative. The assemblages of CRP-2/2A and the upper c. 250 m of CRP-3 are interpreted as representing a predominantly woody vegetation, including Nothofagus and Libocedrus with local areas of grass in the more exposed locations. A cool climate is interpreted to have prevailed throughout both cores. However, beneath c. 250 metres below sea floor in CRP-3, the dominant woody vegetation is supplemented by pockets of Palmae, ?Proteaceae and 'warm' climate grasses. This association represents vegetation growth in sheltered, moist sites - possibly north-facing mid-slopes or the coastal fringe. It may also represent remnant vegetation that grew in moist, temperate conditions during the Middle to Late Eocene, previously interpreted from the Southern McMurdo Sound erratics and lower part of the CIROS-1 drillhole. The phytolith analysis compares well to the terrestrial palynomorph record from both cores and provides additional independent taxonomic and climatic interpretations.植硅体（Phytoliths，硅质植物微化石）已从南极维多利亚地盆地罗伯茨角外钻探获取的CRP-2/2A与CRP-3钻孔的新生代沉积物（约34至17百万年（Ma））中提取。该植硅体组合较为稀少，但保存完好，以与现代乔木或灌木相似的球形形态占主导；同时存在少量与现代草本植物形态相仿的罕见植硅体。但受限于植硅体数据的匮乏，所有相关解释均为试探性结论。针对CRP-2/2A钻孔与CRP-3钻孔上部约250米的植硅体组合，研究推断其代表以木本植被为主的群落，包含南山毛榉属（Nothofagus）与翠柏属（Libocedrus），在暴露程度更高的局部区域伴生有草本植被。两个钻孔均显示整体处于凉爽气候环境。但在CRP-3钻孔海底以下约250米处，优势木本植被中夹杂有斑块状分布的棕榈科（Palmae）、疑似山龙眼科（?Proteaceae）以及‘暖型’草本植物。该组合代表遮蔽湿润生境中的植被发育——此类生境可能为朝北的中坡或海岸带；该植被群落也可能代表始新世中晚期湿润温带环境下发育的残存植被，此前该类结论曾通过南麦克默多湾漂砾与CIROS-1钻孔下部的记录得到推断。本次植硅体分析与两个钻孔的陆生孢粉记录吻合度较高，可为分类学与气候学解读提供独立的补充依据。