在白纪晚期,鱼类耳石结合的有机物质中发生了同位素转移
Zixuan C Rao1,2, Jessica A Lueders-Dumont1,3,4, Gary L Stringer5
1Department of Geosciences, Princeton University, Princeton, NJ 08544.
概括
化石鱼耳石中的同位素揭示了白纪晚期的环境变化. 温暖的气候与较低的同位素值相关,这表明海洋缺氧区域与全球温度之间存在长期联系.
科学领域:
- 古气候学 古气候学
- 地质化学 地质化学
- 古生物学的古生物学
背景情况:
- 化石鱼耳石含有保存的有机物质,适合地质化学分析.
- 有机物中的同位素 (δ15N) 可以作为过去环境条件的代理.
- 重建晚白时期的海洋学和气候对于理解长期地球系统动态至关重要.
研究的目的:
- 为了分析来自晚白纪的化石鱼耳石中的同位素.
- 研究同位素与环境变化,特别是气候和海洋条件之间的关系.
- 评估石有机物作为古气候代理物的可靠性.
主要方法:
- 对同位素比率 (δ15N) 和化石石结合有机物中的含量进行分析.
- 对来自三种鱼类 (Eutawichthys maastrichtiensis*,Eutawichthys zideki*和Pterothrissus* sp.) 的耳石进行了检查. 来自坎帕尼亚和马斯特里希特的沉积物.
- 评估清洁方案和保存状态对地球化学信号的影响.
主要成果:
- 奥托利特有机物 δ 15 N 和 N 含量对清洁方法和保存状态强大.
- 所有分析的物种都表现出从坎帕尼亚到马斯特里希特的耳骨质 δ15N (~4‰) 的显著增加.
- 观察到的δ15N转移在各个属和沉积物中是一致的,表明区域或更大的环境信号.
结论:
- 从坎帕尼亚到马斯特里希特时代的δ15N增加被解释为环境信号,可能与全球气候有关.
- 坎帕尼亚时期全球气温升高可能导致δ15N值降低,反映了海洋脱率下降和缺氧区 (ODZs) 收缩.
- 一致的δ15N-气候相关性表明ODZ与过去8000万年气候之间存在稳定的关系,并持续到白纪末期的灭绝.
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