摘要:
提要：通过山西榆社盆地新近系高庄组剖面的野外地质调查以及沉积物粒度、碳酸盐、磁化率等环境指标的分析，结合前人的ESR测年资料，分析了上新世早期高庄组的沉积环境演化特征。认为榆社盆地上新世早期（5.25～3.16 Ma）以温暖湿润条件下的湖泊环境为主，存在多次强弱不等的干旱气候波动，且榆社古湖水体经历了3次稳定增加—波动性增加的周期性变化。5.25～4.50 Ma盆地演化进入初次裂陷活动期，水体经历稳定加深阶段—波动加深阶段，形成桃阳段地层；4.44～3.89 Ma盆地演化进入裂陷稳定期，对应南庄沟段的沉积，水体经历稳定阶段—波动加深阶段；3.81～3.16 Ma盆地演化进入二次裂陷活动期，对应醋柳沟段的沉积，水体经历稳定加深阶段—波动平衡阶段，其中3.50～3.33 Ma出现极端干旱的气候事件，而后向温暖湿润环境转化。
Abstract:
Abstract：Based on field geological survey and an analysis of such environmental indicators as grain sizes, magnetic susceptibility and carbonate content in combination with ESR age data provided by previous researchers, this paper discusses the variation of the depositional environment in the Gaozhuang Formation during the early Pliocene. The analytical results show that, in the early Pliocene (5.25～3.16 Ma), the Yushe Basin was mainly warm and wet in climate, with unsteady short-term drought, and its paleolake underwent three seasonal changes of the water level from steady increase to wavy increase. During 5.25～4.50 Ma, the basin evolved into the first strong rift stage, its paleolake underwent a change of its water level from steady increase to wavy increase, forming Taoyang Member strata. During 4.44～3.89 Ma, the basin evolved into the steady rift stage, its paleolake underwent a change of its water level from steady stabilization to wavy increase, forming Nanzhuanggou Member strata. During 3.81～3.16Ma, the basin evolved into the second strong rift stage, its paleolake underwent a change of its water level from steady increase to wavy balance, forming Culiugou Member strata, and the extreme dry climate occurred in 3.50～3.33Ma, after which the climate became warm and wet.
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