三水盆地古近纪早期微体生物群及其古环境意义

 对三水盆地SB-01钻孔下古近系地层进行了微体化石分析，共发现介形类7属10种，分布于5个层位；轮藻化石9属15种，见于3个层位。根据介形类和轮藻化石的分布、丰度和分异度变化，讨论了三水盆地古近纪早期的古环境变化。分析结果表明，三水盆地古近纪早期可划分为4个环境演化阶段。阶段A（89.0~75.5 m）：气候较干燥，水体较浅的半咸水环境；阶段B（75.5~53.5 m）：气候温暖潮湿为主，湖平面上升，水体盐度仍较高；阶段C（53.5 ~ 21.0 m）：温湿－干旱气候条件交替出现，湖平面和水体盐度波动频繁；阶段D（21.0 ~ 5.2 m）：气候温暖湿润为主，水体较深，湖水逐渐淡化，相应于湖盆发育盛期。

Early Paleogene Microfossils and their Palaeoenvironmental Implications in Sanshui Basin, South China

Early Paleogene microfossils of core SB-01 in the Sanshui Basin are analyzed in this paper.Ten ostracod species referred to 7 genera and 15 charophyte species referred to 9 genera are identified. Ostracods mainly occur in 5 core intervals and charophytes are only observed in 3 core intervals. Ostracod and charophyte records allow to recognize 4 environmental stages in the Sanshui Basin during the early Paleogene:Stage A (89.0~75.5 m) dryer climate and shallow brackish waters；Stage B (75.5~53.5 m) warm and humid climate, increased water level and higher salinity; Stage C (53.5~21.0 m) – alternative of humid and arid climate conditions, rapid fluctuations in water depth and salinity and Stage D (21.0~5.2 m) prevailing warm and humid climate, lake waters with reduced salinity.