本文選題：瓜德魯普世末滅絕事件 + Zn同位素　； 參考：《中國地質大學(北京)》2017年碩士論文

【摘要】：瓜德魯普世末滅絕事件(GLB事件)是一次發(fā)生在中二疊世與晚二疊世過渡時期的全球性集群絕滅事件。相對于二疊紀末的生物大滅絕而言,其研究程度較低。對于此次滅絕事件在全球的影響范圍、選擇性、程度、起止時間以及成因機制,都存在著較大爭議。因此,我們需要尋找一個新的地球化學指標,對此次滅絕事件進行更精確的解析。鋅是一種生物必需的微量營養(yǎng)元素,廣泛參與多種生物過程,對生物的生命活動起著重要的作用。由于碳酸鹽巖與海水之間的Zn同位素分餾幾乎不受溫度影響,碳酸鹽巖中真實地保存了表層海水中原始的Zn同位素的信息。本文利用Zn同位素,對瓜德魯普世末生物滅絕時期古氣候和古環(huán)境的變化對生物演化所產(chǎn)生的影響進行研究,并探討瓜德魯普世末滅絕事件的可能滅絕機制。本文通過對樂平統(tǒng)底界GSSP廣西來賓蓬萊灘剖面的Zn同位素研究發(fā)現(xiàn),GLB附近出現(xiàn)了兩次明顯的Zn同位素負異常。第一次Zn同位素負異常開始于Jinogondolella xuanhanensis與J.granti牙形類化石帶的過渡層,負偏范圍達0.46‰,對應珊瑚和腕足的滅絕層;第二次Zn同位素負異常開始于J.granti牙形類化石帶的頂部,負偏范圍達0.65‰,對應□類、牙形刺和菊石的滅絕層。說明Zn同位素組成的變化與GLB事件在時間上具有一致性。結合當時的古環(huán)境背景,本文認為滅絕的第一幕是與峨眉山大火成巖省的火山活動有關,而滅絕的第二幕是與全球性的大規(guī)模海退相關。因此,Zn同位素對瓜德魯普世末生物滅絕事件的滅絕機制,起到了重要的約束作用。
[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，

本文編號：1814148