Late Cretaceous and Cenozoic paleoceanography from north-east Atlantic ferromanganese crust microstratigraphy
Late Cretaceous and Cenozoic paleoceanography from north-east Atlantic ferromanganese crust microstratigraphy
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DOI：
10.1016/j.margeo.2020.106122
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发表时间：
2020-04
期刊：
影响因子：
2.9
通讯作者：
P. Josso;J. Rushton;P. Lusty;A. Matthews;S. Chenery;D. Holwell;S. Kemp;B. Murton
中科院分区：
文献类型：
--
作者：
P. Josso;J. Rushton;P. Lusty;A. Matthews;S. Chenery;D. Holwell;S. Kemp;B. Murton
海洋水成铁锰结壳(铁-锰结壳)在数百万年的时间里直接从周围的海水中沉淀下来。它们非常慢的生长速度和物理化学性质意味着它们可以从海水中吸附大量元素。因此，它们提供了海水随时间演变的浓缩记录，可用于古海洋学重建。在这里，我们介绍了对位于热带东北大西洋热带海山顶端的铁锰结壳路面上获得的岩心样品进行高分辨率、地层、结构和地球化学调查的结果。在一个限制很好的年龄模型的背景下，提出了一些观察和解释，该模型跨越了过去75岁±2岁。该岩心与晚白垩世以来形成的太平洋铁锰结壳具有结构地层一致性，突出了全球海洋和气候现象对铁锰结壳发育的一级控制作用。在铁锰结壳中观察到的所有主要间歇期都与整个大西洋发生的侵蚀事件同时发生。高分辨率的地球化学数据表明，在cm-μm尺度上，铁-锰结壳的成分具有变异性。主要的控制因素包括重大海洋事件、矿物结构和微地形。
Oceanic hydrogenetic ferromanganese (Fe-Mn) crusts precipitate directly from ambient seawater over millions of years. Their very slow growth rates and physio-chemical properties mean that they adsorb numerous elements from seawater. As such, they provide condensed records of seawater evolution through time that can be used for paleoceanographic reconstruction. Here, we present the results of a high-resolution, stratigraphic, textural and geochemical investigation of a core sample, obtained from a Fe-Mn crust pavement, located on the summit of Tropic Seamount in the tropical north-east Atlantic Ocean. A number of observations and interpretations are proposed, within the context of a well-constrained age model, spanning the last 75 ± 2 Myr. This core has textural stratigraphic coherence with Pacific Fe-Mn crusts formed since the Late Cretaceous, highlighting that global oceanic and climatic phenomena exert first-order controls on Fe-Mn crust development. All major hiatuses observed in the Fe-Mn crusts are contemporaneous with erosion events occurring throughout the Atlantic Ocean. High-resolution geochemical data indicate that there is variability in the composition of Fe-Mn crusts at the cm to μm scale. The dominant factors controlling this include major oceanographic events, mineral textures and micro-topography.