The Late Precambrian Paleo-Ocean Evolution of the Southeast Yangtze Continental Margin: REE Record
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摘要: 本文采用中子活化方法分析了晚震旦～早寒武纪１９件样品的稀土元素组成，发现硅质岩石ＲＥＥ配分形式有着复杂的变化，初步可以划分为五种类型，包括“台地型”、“红海型”、“海水型”及两种特殊的配分形式。剖面上Ｃｅ异常由小到大的演变反映了古海洋底层水由缺氧环境向氧化条件的逐渐转化。正Ｅｕ异常的出现代表了热水沉积事件的存在。Abstract: We report REE (rare earth elements) data of 19 samples from Upper Sinian - Lower Cambrian chens by neutron activation analysis. The REE patterns with respect to an average shale show complicate changes and are preliminarily classified into different types, including "platform-type", "Red Sea-type", "seawater-type"and two distinctive types. The Ce depletion in the section exhibits a progressive increase from the lower to upper beds. The Ce anomaly,as an indicator of redox conditions, reveals that paleo-ocean bottom seawater in this area was anoxic during Late Precambrian and an oxidizing environment occurred in Early Cambrian.The occurrence of positive Eu anomaly may indicate submarine hydrothermal deposition.
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Key words:
- Chert /
- REE /
- Paleo-ocean /
- Anoxic environment /
- Submarine hydrothermal event
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