| 摘要: |
| 为了揭示歧口凹陷古近系沙河街组白云岩的成因,对50件白云岩样品的稀土元素地球化学特征进行分析研究,并利用北美页岩(NASC)对分析结果进行标准化处理。结果表明:白云岩样品的稀土元素表现出轻稀土富集、重稀土亏损的分配模式,稀土元素La异常值和Y/Ho具有负相关关系,稀土元素总量与Al含量呈正向同步变化关系而与Ca含量呈反向关系,指示其形成于湖相环境;同时还具有轻微的La正异常和Ce负异常,较高的Y正异常和Y/Ho比值说明白云岩化流体受到海水的影响;白云岩样品的Eu正异常和较高的包裹体均一温度表明其受到热液的改造作用;歧口凹陷沙河街组白云岩其形成于湖相环境中,成岩流体受到海水和热液的影响。 |
| 关键词: 古近系 白云岩 稀土元素特征 歧口凹陷 |
| DOI：10.3969/j.issn.1673-5005.2014.02.001 |
| 分类号:P 581 〖HTH〗 |
| 基金项目:中国石油重大专项 (2008E-0601) |
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| REE characteristics and genesis of dolostones from Paleogene Shahejie Formation in Qikou depression |
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YANG Yang1, GAO Fu-hong1, PU Xiu-gang2
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(1.College of Earth Sciences,Jilin University,Changchun 130061,China;2.Research Institute of Exploration and Development,Dagang Oilfield Company,PetroChina,Tianjin 300280,China)
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| Abstract: |
| The REE of 50dolostone samples from Paleogene Shahejie Formation in Qikou depression were analyzed, with the aim of determining the genesis of dolostone in this region. The data were normalized to the standard NASC, and the results demonstrate that most of samples share similar REE distribution patterns with LREE enrichment and HREE depletion. The negative correlation between δLa and Y/Ho,the positive correlation between w(REE) and w(Al) and the negative correlation between w(REE) and w(Ca) imply that the dolostones are deposited in a lacustrine environment. Characteristics of the positive La anomaly,slightly negative Ce anomaly,positive Y anomaly and relatively higher ratio of Y/Ho indicate that the diagenetic fluids of dolomitization are probably influenced by seawater. The positive Eu anomaly and high homogenization temperatures suggest that the dolostones are affected by hydrothermal fluid. The dolostones from Paleogene Shahejie Formation in Qikou depression are the products of lacustrine dolomitization, and the diagenetic fluids are influnced by seawater and hydrothermal fluid. |
| Key words: Paleogene dolostone REE characteristics Qikou depression |
