中文摘要：

本文分析了三水盆地SB-01孔微体古生物群的组合特征，结合全岩碳酸盐碳、氧同位素数据探讨了古新统-始新统界线在该孔中的具体层位．介形类化石分为两个组合，即Eucypris sanshuiensis组合（89．0—73．38m）和Sinocypris nitela-Cyprois buxinensis—Limnocythere honggangensis组合（73．38—0m）．前者属种单调，丰度低，后者前期和中期属种单调，丰度低，而后期属种相对较为丰富，丰度快速上升；轮藻化石也可分为两个组合，即Peckicharasubspherica．Rhabdocharafiangduensis组合（89．0—73．38m）和cyrogona qianjiangica-Obtusochara brevicylindrica组合（73．38—53．75m）．前者属种丰富，丰度高，化石个体较大，后者属种单调，丰度很低，化石个体较小．在孔深73．38m处，微体古生物群发生重大更替，且全岩碳酸盐碳同位素（下降幅度大于3．0％。）、氧同位素值均在此处发生突变，这与古新世一始新世最热事件（PETM）时期的地质记录相一致，因而认为三水盆地古新统-始新统界线在孔深73．38m处．

英文摘要：

Characteristics of microfossils assemblages of core SB-01 from Sanshui Basin have been analysised in this paper. Based on micropaleontological study and data from carbon and oxygen isotopes of bulk carbonates, which depth of Paleoeene-Eocene boundary from the core was discussed. Ostracode assemblages include the Sinocypris nitela-Cyprois buxinensis-Limno- cythere honggangensis assemblage （89.0 - 73.38 m） with few species and low abundance and the Sinocypris nitela-Cyprois buxinensis-Limnocythere honggangensis assemblage （73.38 - 0 m） with few species and low abundance during early and middle the core deposition and relatively many species and abundance increasing quickly of the late time of the core deposition;Charo- phyte assemblages contain the Peckichara subspherica-Rhabdochara fiangduensis assemblage （89.0-73.38 m） with rich species,high abundance and large sizes of fossils and the Gyrogona qianjiangica-Obtusochara brevicylindrica assemblage （73.38 -53.75 m） with few species, low abundance and small sizes of fossils. At 73.38 m core depth, the great changes of microfossils assemblages and carbon isotopes values （decrease by more than 3.0 ‰） and oxygen isotopes values of bulk carbonates take place ,which consist with the geological records of the Paleocene-Eoeene Thermal Maximum （PETM）. Hence, Paleocene-Eocene boundary of SanShui Basin should be roughly placed at 73.38 m core depth.