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首页> 外文期刊>Palaeogeography, Palaeoclimatology, Palaeoecology: An International Journal for the Geo-Sciences >Paleoceanographic and paleoclimatic similarities between Mediterranean sapropels and Cretaceous black shales
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Paleoceanographic and paleoclimatic similarities between Mediterranean sapropels and Cretaceous black shales

机译：地中海腐殖质和白垩纪黑色页岩之间的古海洋学和古气候相似性

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摘要

Pliocene-Quaternary sapropels of the Mediterranean Sea and mid-Cretaceous black shales share many distinctive properties. Organic carbon concentrations that often exceed 5% in both types of sequences record episodes of exceptional accumulation of organic matter. Although both are rich in marine organic matter, they have high C/N ratios that mimic those of land-plant organic matter, which suggests less-efficient organic matter recycling than in the modem ocean. The coupled presence of isorenieratene derivatives and low delta N-15 values that result from microbial primary productivity indicates that photic zone anoxia existed during their formation and implies strong stratification of the surface ocean. Enrichments of redox-sensitive metals and sediment laminations indicate that anoxia existed deeper in the water column and at the seafloor. Multiple proxies indicate freshening of surface waters of the Mediterranean and imply periods of wetter climate during times of sapropel deposition. Episodes of black shale deposition similarly coincide with times of wetter climate. These comparisons suggest that the wetter climate created similar conditions of surface salinity stratification that enhanced microbial primary production and magnified organic matter export during deposition of both the Mediterranean sapropels and mid-Cretaceous black shales. (c) 2005 Elsevier B.V. All rights reserved.
机译：地中海的上新世-第四纪腐质和白垩纪中部黑色页岩具有许多独特的性质。在两种类型的序列中，有机碳浓度通常都超过5％，这表明有机物质异常积累。尽管两者均富含海洋有机物，但它们具有高的C / N比，可模仿陆地植物有机物的C / N比，这表明有机物的循环利用效率比现代海洋低。异戊二烯衍生物和微生物初级生产力导致的低N-15值的耦合存在，表明在其形成过程中存在光区缺氧，这意味着表层海洋强烈分层。氧化还原敏感金属和沉积物叠层的富集表明缺氧存在于水柱和海底更深处。多个代理表明，地中海地表水清新，这意味着腐泥沉积期间气候更湿润。类似地，黑色页岩沉积的发生与潮湿的气候相吻合。这些比较表明，潮湿的气候创造了相似的表面盐分分层条件，从而增强了地中海腐殖质和白垩纪中部黑色页岩的沉积，从而增加了微生物的初级生产力并增加了有机物的出口。 （c）2005 Elsevier B.V.保留所有权利。

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