Palynological, geochemical, and mineralogical characteristics of the Early Jurassic Liasidium Event in the Cleveland Basin, Yorkshire, UK Palynological, geochemical, and mineralogical characteristics of the Early Jurassic Liasidium Event in the Cleveland Basin, Yorkshire, UK
Palynological, geochemical, and mineralogical characteristics of the Early Jurassic Liasidium Event in the Cleveland Basin, Yorkshire, UK Palynological, geochemical, and mineralogical characteristics of the Early Jurassic Liasidium Event in the Cleveland Basin, Yorkshire, UK
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英国约克郡克利夫兰盆地早侏罗世 Liasidium 事件的孢粉学、地球化学和矿物学特征 英国约克郡克利夫兰盆地早侏罗世 Liasidium 事件的孢粉学、地球化学和矿物学特征
DOI：
10.1127/nos/2019/0536
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发表时间：
2020
影响因子：
2.2
通讯作者：
Hesselbo S
中科院分区：
文献类型：
--
作者：
Hesselbo S
英国约克郡克利夫兰盆地罗宾汉湾的浅海层序研究了早侏罗世（Sinemurian中期）一个先前提出的高温事件。孢粉学研究证实，独特的甲藻孢囊Liasidium variabile的地层范围非常接近对应于尖果藻带。Liasidium variabile的范围也对应于在散装有机质中测得的碳同位素的总体负偏移，在这里表现出在中间的尖齿区的双重尖峰。此外，Liasidium变量丰度跟踪整体海进-海退相趋势，甲藻孢囊的峰值丰度对应于最深的水相和最大洪水。通过对粉末样品的视觉描述和手持式X射线荧光分析确定的岩石周期（准层序）与先前提出的短偏心周期相匹配，并允许提出至少一百万年的事件总持续时间。粘土矿物学的变化，整个部分确定的全岩X射线衍射和扫描电子显微镜被证明是在很大程度上与自生过程，既不支持也不反驳同时代的古气候变化的命题。罗宾汉湾描述的Liasidium事件的综合特征类似于早侏罗世Toarcian海洋缺氧事件，但远不如后者极端，尽管在这个地方，没有证据表明发生了显著的底层水脱氧。
A previously proposed hyperthermal episode in the Early Jurassic (mid-Sinemurian) is investigated from the shallow marine succession at Robin Hood’s Bay, Cleveland Basin, Yorkshire, UK. Palynological study confirms that the stratigraphical extent of the distinctive dinoflagellate cyst Liasidium variabile corresponds very closely to the oxynotum Zone. The range of Liasidium variabile also corresponds to an overall negative excursion in carbon-isotopes measured in bulk organic matter, which here exhibits a double spike in the middle oxynotum Zone. Additionally, Liasidium variabile abundances track overall transgressive-regressive facies trends with peak abundance of dinoflagellate cysts corresponding to deepest water facies and maximum flooding. Lithological cycles (parasequences), defined by visual description and hand-held X-ray fluorescence analysis of powdered samples, match previously suggested short eccentricity cycles, and allow a total duration for the event of at least one million years to be suggested. Changes in clay mineralogy throughout the section determined by whole rock X-ray diffraction and scanning electron microscopy are shown to be largely related to authigenic processes, and neither support nor refute the proposition of coeval palaeoclimate changes. The combined characteristics of the Liasidium Event described from Robin Hood’s Bay are similar to, but much less extreme than, the Early Jurassic Toarcian Oceanic Anoxic Event albeit, at this locality, there is no evidence for the development of significant bottom water deoxygenation.