孔凡翠, 杨瑞东, 魏怀瑞, 文雪峰, 韩晓彤, 高军波. 贵州威宁草海第四系窑上组沉积物微量元素地球化学特征及其古环境意义[J]. 海洋地质与第四纪地质, 2011, 31(5): 117-126. DOI: 10.3724/SP.J.1140.2011.05117
引用本文: 孔凡翠, 杨瑞东, 魏怀瑞, 文雪峰, 韩晓彤, 高军波. 贵州威宁草海第四系窑上组沉积物微量元素地球化学特征及其古环境意义[J]. 海洋地质与第四纪地质, 2011, 31(5): 117-126. DOI: 10.3724/SP.J.1140.2011.05117
KONG Fancui, YANG Ruidong, WEI Huairui, WEN Xuefeng, HAN Xiaotong, GAO Junbo. GEOCHEMISTRY OF TRACE ELEMENTS OF THE QUATERNARY SEDIMENTS OF YAOSHANG FORMATION IN WEINING COUNTY, GUIZHOU PROVINCE AND ITS PALEOENVIRONMENTAL IMPLICATIONS[J]. Marine Geology & Quaternary Geology, 2011, 31(5): 117-126. DOI: 10.3724/SP.J.1140.2011.05117
Citation: KONG Fancui, YANG Ruidong, WEI Huairui, WEN Xuefeng, HAN Xiaotong, GAO Junbo. GEOCHEMISTRY OF TRACE ELEMENTS OF THE QUATERNARY SEDIMENTS OF YAOSHANG FORMATION IN WEINING COUNTY, GUIZHOU PROVINCE AND ITS PALEOENVIRONMENTAL IMPLICATIONS[J]. Marine Geology & Quaternary Geology, 2011, 31(5): 117-126. DOI: 10.3724/SP.J.1140.2011.05117

贵州威宁草海第四系窑上组沉积物微量元素地球化学特征及其古环境意义

GEOCHEMISTRY OF TRACE ELEMENTS OF THE QUATERNARY SEDIMENTS OF YAOSHANG FORMATION IN WEINING COUNTY, GUIZHOU PROVINCE AND ITS PALEOENVIRONMENTAL IMPLICATIONS

  • 摘要: 分析了贵州威宁草海第四系窑上组剖面微量元素和稀土元素地球化学特征,结合前人研究的介形类、孢粉等资料,探讨了沉积物微量元素垂直变化反映的沉积环境。结果表明,Li、Ba、Sr等14种微量元素有着很好的相关性。∑REE高,δCe、δEu呈现负异常的总体特征,但δCe在第7、11层表现为正异常;轻重稀土分馏较大,具有轻稀土富集、缓右倾斜型的稀土元素配分模式。窑上组该剖面沉积物元素对比值和稀土元素特征参数具有分带性,自下而上可分为3个地球化学演化带。Li、Ba、Sr等14种微量元素含量及Rb/Sr、Sr/Ba、Sr/Cu等元素对比值表明窑上组第2、6、8、10、12层沉积时期为相对干热气候,其余层为较冷湿气候;Sr/Cu值为1~5,印证了威宁草海在早更新世为亚热带高原季风湿润气候的说法。Sr/Ba值为0.2~0.5,印证了草海是淡水沉积的结论。沉积物源风化强烈,或者有高稀土含量的二叠系玄武岩风化土壤加入。Sr/Cu和Rb/Sr结合可以作为气候变化指标,它们比值的变化说明了该剖面湖泊区沉积时古气候经历了由温暖干燥向冷湿变化的趋势。

     

    Abstract: Geochemistry of trace elements and REE of the Quaternary sediments in the Yaoshang Formation in Weining country, Guizhou,China were analyzed. Based on the previous studies about Ostracoda and pollen, we discussed the sedimentary environmental changes through the vertical variation of elements. Our results show that the 14 trace elements (eg. Li, Ba, Sr) are well correlated. Generally, ∑REE is very high, and δCe and δEu are negative,except that Ce in the layers 7 and 11 are positive. LREE and HREE fractionation is obvious. And the chondrite normalized samples show a distribution pattern of LREE enrichment with gentle incline to the right. The parameter of elements ratio and REE are characterized by zonation.The content the 14 trace elements and Rb/Sr、Sr/Ba、Sr/Cu ratio indicate a relatively dry and hot climate in the layers of 2,6,8,10,12 of the Yaoshang Formation while the other layers formed undera colder and wetter climate. Sr/Cu changes between 1 and 5, indicating a humid subtropical plateau monsoon climate. Sr/Ba changing between 0.2~0.5 indicates that the Caohai sediment was deposiled in a freshwater enviroment, suggesting a very strong weathering of the parent nock of the Permian basalt which is high in REE content. The combination of Sr/Cu and Rb/Sr ratio values can be used as the indicator of climatic change.

     

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