Glendonites and seep-related carbonate bodies from the Jurassic/Cretaceous boundary interval of West Spitsbergen were studied using mineralogical, isotopic, and geochemical methods. The stratigraphic distribution of seep-related carbonate bodies and glendonites (pseudomorphs after ikaite, Ca(CO₃)·6H₂O) reveals that although they can be occasionally found close to each other, their formation differs through time. Seep carbonates are found in the Oxfordian, Kimmeridgian, Volgian, and Ryazanian deposits, while glendonites appear in the Valanginian–Hauterivian and Middle Aptian–Lower Albian deposits of West Spitsbergen. Furthermore, numerous appearances of seep carbonates correlate with warming and shelf dysoxic–anoxic events in the Arctic, while glendonite occurrences correlate with cooling events. The δ¹³C values obtained for seep-related carbonates and glendonite samples reflect mixed sources including thermogenic and biogenic methane, oil fractions, decomposing organic matter, and dissolved inorganic carbon. We assume the precipitation of seep carbonates was caused by methanogenesis and anaerobic oxidation of organic matter promoting dense communities of benthic organisms and carbonate precipitation in warm climatic condition. At the end of the Ryazanian, shallowing of the basin coupled with climate cooling led to decrease in methanogenesis and anaerobic decomposition of methane and organic matter. Locally, in areas of anaerobic organic matter oxidation under low bottom temperatures, ikaite crystallized.

Graphical abstract

中文翻译：

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西斯匹次卑尔根岛晚侏罗世-早白垩世的伊凯石与渗流相关的碳酸盐降水：寒冷气候与温暖气候的证据？

使用矿物学、同位素和地球化学方法对西斯匹次卑尔根侏罗纪/白垩纪边界层段的硅藻土和与渗流相关的碳酸盐体进行了研究。与渗流相关的碳酸盐岩体和硅藻土（钙镁石的假形体，Ca(CO ₃ )·6H ₂ O）的地层分布表明，尽管偶尔可以发现它们彼此靠近，但它们的形成随时间而变化。渗流碳酸盐存在于牛津阶、奇莫里阶、伏尔加阶和梁赞阶沉积物中，而硅钙石则出现在西斯匹次卑尔根群岛的瓦朗吉阶-欧特里阶和中阿普阶阶-下阿尔布阶沉积物中。此外，大量渗漏碳酸盐的出现与北极变暖和陆架缺氧-缺氧事件相关，而硅藻土的出现则与变冷事件相关。与渗流相关的碳酸盐和硅藻土样品获得的δ ¹³ C 值反映了混合来源，包括热成因和生物成因甲烷、石油馏分、分解有机物和溶解的无机碳。我们假设渗透碳酸盐的沉淀是由有机物的产甲烷和厌氧氧化促进底栖生物密集群落和温暖气候条件下碳酸盐沉淀引起的。梁赞纪末期，盆地变浅，加上气候变冷，导致产甲烷作用减少，甲烷和有机物的厌氧分解减少。局部地区，在底部温度较低的厌氧有机物氧化区域，伊卡石结晶。

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