二叠纪瓜德鲁普世末生物大灭绝的Zn同位素研究

发布时间：2018-04-28 06:26

  本文选题：瓜德鲁普世末灭绝事件 + Zn同位素　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：瓜德鲁普世末灭绝事件(GLB事件)是一次发生在中二叠世与晚二叠世过渡时期的全球性集群绝灭事件。相对于二叠纪末的生物大灭绝而言,其研究程度较低。对于此次灭绝事件在全球的影响范围、选择性、程度、起止时间以及成因机制,都存在着较大争议。因此,我们需要寻找一个新的地球化学指标,对此次灭绝事件进行更精确的解析。锌是一种生物必需的微量营养元素,广泛参与多种生物过程,对生物的生命活动起着重要的作用。由于碳酸盐岩与海水之间的Zn同位素分馏几乎不受温度影响,碳酸盐岩中真实地保存了表层海水中原始的Zn同位素的信息。本文利用Zn同位素,对瓜德鲁普世末生物灭绝时期古气候和古环境的变化对生物演化所产生的影响进行研究,并探讨瓜德鲁普世末灭绝事件的可能灭绝机制。本文通过对乐平统底界GSSP广西来宾蓬莱滩剖面的Zn同位素研究发现,GLB附近出现了两次明显的Zn同位素负异常。第一次Zn同位素负异常开始于Jinogondolella xuanhanensis与J.granti牙形类化石带的过渡层,负偏范围达0.46‰,对应珊瑚和腕足的灭绝层;第二次Zn同位素负异常开始于J.granti牙形类化石带的顶部,负偏范围达0.65‰,对应□类、牙形刺和菊石的灭绝层。说明Zn同位素组成的变化与GLB事件在时间上具有一致性。结合当时的古环境背景,本文认为灭绝的第一幕是与峨眉山大火成岩省的火山活动有关,而灭绝的第二幕是与全球性的大规模海退相关。因此,Zn同位素对瓜德鲁普世末生物灭绝事件的灭绝机制,起到了重要的约束作用。
[Abstract]:The GLB event is a global cluster extinction event that occurred during the transition period between the Middle Permian and the late Permian. Compared with the late Permian mass extinction, its research degree is relatively low. The scope, selectivity, extent, starting and ending time and mechanism of the extinction in the world are controversial. Therefore, we need to find a new geochemical indicator for a more accurate analysis of the extinction event. Zinc is a kind of essential micronutrient element, which is widely involved in many biological processes and plays an important role in biological life activities. Since the fractionation of Zn isotopes between carbonate rocks and seawater is almost unaffected by temperature, the information of the original Zn isotopes in surface seawater is truly preserved in carbonate rocks. In this paper, the effects of paleoclimate and paleoenvironmental changes on biological evolution during the late Guadru extinction period were studied by using Zn isotopes, and the possible extinction mechanism of the late Guadrupu extinction event was discussed. Based on the study of Zn isotopes in the Penglai beach section of Lailinglai, Guangxi, at the bottom boundary of Leping series, it is found that two obvious negative Zn isotopic anomalies occurred near the GLB. The first Zn isotope negative anomaly began in the transitional layer of the Jinogondolella xuanhanensis and J.granti conodont fossil belt, and the negative deviation range was 0.46 鈥，

本文编号：1814148