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深海沉积物中纪-普纪边界:微化石的灭绝和进化变化清楚地定义了普纪的突然开始
概括
研究人员寻找了100年来普世气候变化的证据. 目前的定义依赖于海洋化石,但这种方法在测定普莱斯托时代开始时存在局限性.
科学领域:
- 古气候学 古气候学
- 海洋地质学海洋地质学
- 微观古生物学的古生物学
背景情况:
- 一个世纪以来,对地质学家来说,确定普世时代的开始一直是个挑战.
- 大陆冰川沉积物是不连续的和被侵蚀的,限制了它们作为时间标记的使用.
- 地中海上升的普略世-普世海洋沉积物是确定时代开始的关键焦点.
研究的目的:
- 评估使用*Anomalina baltica*首次出现作为普莱斯托时代开始的标记物的可靠性.
- 评估海洋微化石的适宜性,以确定主要地质时代的界限.
主要方法:
- 分析地中海地区的沉积部分.
- 在这些沉积物中检查化石Foraminifera,特别是*Anomalina baltica*.
- 化石发生与古气候指标和冰川事件的相关性.
主要成果:
- 在地中海沉积物中没有发现单一气候事件启动普莱斯托纪的明确证据.
- 基于*Anomalina baltica*的普莱斯托时代开始的定义是有问题的,因为它的局部分布和潜在的环境影响.
- *Anomalina baltica*在地中海首次出现的时间与第一个冰川开始的时间不完全一致.
结论:
- 目前使用*Anomalina baltica*对纪边界的定义是不充分的,并且在地理上受到限制.
- 依靠单一物种的外观来定义时代缺乏强大的古气候证明.
- 需要进一步的研究,以建立可靠的标志物来确定普莱斯托时代的开始,可能整合多个古气候代理.
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