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三峡地区九龙湾剖面陡山沱组帽碳酸盐岩中氧化还原敏感元素的含量表现出两期明显的富集,分别出现在帽碳酸盐岩底界以上0.8和3.3m附近,是由于甲烷的渗漏和氧化造成短暂的还原环境.帽碳酸盐岩中REE+Y配分呈现3种基本形态,下部2.45m内显示淡水环境,与冰期之后的冰融淡水涌入吻合;帽碳酸盐岩底界之上2.45～3.3m可能因为深部海水的上涌混合,表现出与古海水相似的形态;在3.3m以上受成岩作用的影响,转变为HREE亏损的“帽型”配分形态.3个阶段REE+Y配分形态的转变展示了冰期后浅海先是以淡水为主导(且因甲烷渗漏氧化出现短暂缺氧),随着海进和深部海水上涌、淡水融入大洋盆地及后来浅海浮游(微)生物的繁盛,造成水/沉积物界面附近又缺氧的过程.
The contents of redox-sensitive elements in the Doushantuo cap-cap rocks of the Jiulongwan section of the Three Gorges area show two distinct enrichments that occur at around 0.8 and 3.3 m above the cap carbonate boundary, respectively, due to methane Of the REE + Y fraction in the cap carbonate rocks showed three basic morphologies, the freshwater environment showed in the lower part of 2.45 m and coincided with the influx of fresh ice after the ice age; the cap carbonate 2.45 ~ 3.3m above the bottom of the rock bottom may be similar to the paleo-seawater because of the upwelling of the deep seawater. Due to the diagenesis above 3.3m, the “cap” The three-phase REE + Y distribution pattern shows that after the ice age the shallow sea was dominated by fresh water (with a brief oxygen deficiency due to methane seepage), and the fresh water was integrated into the oceanic basin as marine and deep seawater upwells Shallow sea planktonic (micro) biological prosperity, resulting in water / sediment near the interface and hypoxia process.