摘要:针对渭河盆地新近系沉积古环境恢复问题，以渭河盆地固市凹陷荔参1井岩芯资料为例，结合周缘野外露头特征，利用孢粉、介形虫等古生物化石和古盐度、风化指数、B/Ga比、Sr/Ba比、Fe/Mn比、Th/U比、氧化还原条件指标及钴含量推算古水深等地球化学方法，恢复渭河盆地新近系沉积古环境。结果表明：渭河盆地新近系孢粉由中新统高陵群阔叶林、灞河组疏林草原向上新统游河组森林草原植被演变，含浪游土星介、显著真星介等古生物化石，为暖湿转为冷干的半干旱气候特征；微量元素分析显示，新近系古盐度平均值0.65‰、风化指数平均值64.51，B/Ga比值平均2.44、Sr/Ba比值平均0.65，Fe/Mn值平均56.3、Th/U值平均4.36，氧化还原条件指标平均值0.82，钴含量推算最大古水深范围4.16～19.42 m，平均最大古水深13.01 m，认为渭河盆地新近系为中等程度风化陆相淡水—半咸水沉积环境。研究为渭河盆地新近系沉积古环境恢复提供理论基础，也为渭河盆地其他层位及其他盆地沉积古环境恢复提供理论依据。
关键词: 古生物/
微量元素/
古盐度/
最大古水深/
新近系/
渭河盆地
Abstract:Aiming at the restoration of Neogene sedimentary paleo-environment in Weihe Basin, combined with the characteristics of the outcrop in the peripheral section, selected the core data of Lican-1 well in Gushi Sag, used paleontological fossils such as sporopollen and ostracods as well as geochemical characteristics such as paleo-salinity, weathering index, B/Ga ratio, Sr/Ba ratio, Fe/Mn ratio, Th/U ratio, redox index and Co content estimated palaeobathymetry to restore the sedimentary paleo-environment. It shows that vegetation from the broadleaf forest of the Gaoling Group to the sparse forest steppe of the Bahe Formation and the forest steppe of the Youhe Formation based on Neogene palynology, and paleontological fossils including the Ilyocypris cf. Errabundis and Eucypris cf. Notabilis. It shows the characteristics of semi-arid climate from warm to dry. From trace element analysis, paleo-salinity average value is 0.65‰, weathering index average value is 64.51, B/Ga average value is 2.44, Sr/Ba average value is 0.65, Fe/Mn average value is 56.3, Th/U average value is 4.36, redox index average value is 0.82, Co content estimated palaeobathymetry from 4.16~19.42 m, average value is 13.01 m. Combined the oxidative lithology, paleontological fossils and geochemical characteristics, the sedimentary environment of Neogene Weihe Basin is terrestrial fresh water-brackish lake of weathering. This method not only provides a theoretical basis for other stratigraphic sedimentary paleo-environment restoration in Weihe Basin, but also provides a theoretical basis for sedimentary paleo-environment restoration of different basins.
Key words:Paleontology/
Trace elements/
Paleo-salinity/
Maximum palaeobathymetry/
Neogene/
Weihe Basin
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