Dynamic climate-driven controls on the deposition of the Kimmeridge Clay Formation in the Cleveland Basin, Yorkshire, UK
Dynamic climate-driven controls on the deposition of the Kimmeridge Clay Formation in the Cleveland Basin, Yorkshire, UK
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DOI：
10.5194/cp-15-1581-2019
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发表时间：
2019-01
影响因子：
4.3
通讯作者：
Elizabeth Atar;C. März;A. Aplin;O. Dellwig;Liam Herringshaw;V. Lamoureux-Var;M. Leng;B. Schnetger;T. Wagner
中科院分区：
文献类型：
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作者：
Elizabeth Atar;C. März;A. Aplin;O. Dellwig;Liam Herringshaw;V. Lamoureux-Var;M. Leng;B. Schnetger;T. Wagner
抽象的。基米里奇粘土层（KCF）是一个横向广泛的，总有机碳丰富的继承沉积在整个西北欧在基米里奇-蒂托（晚侏罗世）。它最近被假定，一个扩大的哈德利细胞，加强，但交替的水文循环，严重影响沉积和总有机碳（TOC）富集，促进初级生产力和有机物埋藏在英国部门的北方航道。与这种气候边界条件相一致，岩相学观测，总有机碳和碳酸盐含量，以及主要和微量元素的数据表明，克利夫兰盆地的KCF沉积在劳亚海道的影响下，这些条件。沉积条件在三种状态之间交替变化，在岩性和地球化学记录中产生了明显的周期性：低变泥岩间隔（LVMI），包括富含粘土的泥岩和高变泥岩间隔（HVMI），包括富含TOC的沉积和富含碳酸盐的沉积。低变异性泥岩间隔占研究间隔的主导地位，但被三个交替的富含TOC和富含碳酸盐沉积（HVMI）的2.2 -4 m厚间隔所打断。在较低的可变性泥岩间隔，条件是静态的好氧到亚氧的底层水条件。在较高的可变性泥岩间隔，高度动态的条件下，导致氧化还原系统的反复切换的方式类似于现代深海盆地的波罗的海。在富碳酸盐沉积期间，氧化条件占主导地位，最有可能是由于海流波作用导致海底沉积能量升高。在TOC丰富的沉积过程中，间歇性缺氧-缺氧条件导致氧化还原敏感和硫化物形成的微量金属在海底富集和有机物的保存，和一个活跃的锰-铁微粒穿梭交付氧化还原敏感和硫化物形成的微量金属到海底。此外，TOC-S-Fe关系的基础上，有机物硫化似乎增加了有机物保存在约一半的分析样品在整个核心，而其余的样品要么占主导地位的过量铁输入到系统中或经历黄铁矿氧化和硫损失在氧化事件。新的汞闪烁TOC数据没有提供证据表明，在这段时间内，火山活动增加，与以前的工作一致。在最近的气候建模的背景下，我们的研究提供了一个全面的例子，动态的气候驱动的沉积和氧化还原条件，可以控制TOC和金属积累在一个浅的陆表海，因此，它是关键的理解形成类似的存款在整个地球的历史。
Abstract. The Kimmeridge Clay Formation (KCF) is a laterally extensive, total-organic-carbon-rich succession deposited throughout northwest Europe during the Kimmeridgian–Tithonian (Late Jurassic). It has recently been postulated that an expanded Hadley cell, with an intensified but alternating hydrological cycle, heavily influenced sedimentation and total organic carbon (TOC) enrichment by promoting primary productivity and organic matter burial in the UK sectors of the Boreal Seaway. Consistent with such climate boundary conditions, petrographic observations, total organic carbon and carbonate contents, and major and trace element data presented here indicate that the KCF of the Cleveland Basin was deposited in the Laurasian Seaway under the influence of these conditions. Depositional conditions alternated between three states that produced a distinct cyclicity in the lithological and geochemical records: lower-variability mudstone intervals (LVMIs) which comprise clay-rich mudstone and higher-variability mudstone intervals (HVMIs) which comprise TOC-rich sedimentation and carbonate-rich sedimentation. The lower-variability mudstone intervals dominate the studied interval but are punctuated by three ∼ 2–4 m thick intervals of alternating TOC-rich and carbonate-rich sedimentation (HVMIs). During the lower-variability mudstone intervals, conditions were quiescent with oxic to suboxic bottom water conditions. During the higher-variability mudstone intervals, highly dynamic conditions resulted in repeated switching of the redox system in a way similar to the modern deep basins of the Baltic Sea. During carbonate-rich sedimentation, oxic conditions prevailed, most likely due to elevated depositional energies at the seafloor by current–wave action. During TOC-rich sedimentation, intermittent anoxic–euxinic conditions led to an enrichment of redox-sensitive and sulfide-forming trace metals at the seafloor and a preservation of organic matter, and an active Mn–Fe particulate shuttle delivered redox-sensitive and sulfide-forming trace metals to the seafloor. In addition, based on TOC–S–Fe relationships, organic matter sulfurization appears to have increased organic material preservation in about half of the analysed samples throughout the core, while the remaining samples were either dominated by excess Fe input into the system or experienced pyrite oxidation and sulfur loss during oxygenation events. New Hg∕TOC data do not provide evidence of increased volcanism during this time, consistent with previous work. Set in the context of recent climate modelling, our study provides a comprehensive example of the dynamic climate-driven depositional and redox conditions that can control TOC and metal accumulations in a shallow epicontinental sea, and it is therefore key to understanding the formation of similar deposits throughout Earth's history.