| 摘要: |
| 研究样品于1988年采自太平洋东部CC48孔。通过对沉积物稀土元素地球化学特征的分析发现：（1）各种类型深海沉积物的稀土含量有所差别，以稀土元素总量（∑REE）而论，深海粘土＞硅质软泥＞硅钙质轨泥＞钙质轨泥Z沉积物中的自生矿物、谁质生物成因的非晶质SiO2及碎屑矿物对稀土元素起富集作用，而生物CaCO3则起分散作用。（2）稀土元素含量随深度发生变化，为地层划分提供了依据，应用元素地层学方法将岩芯分成5个层段。（3）据稀土元素分异特征区分出3种沉积环境（CCD之上、CCD之下和过渡型），而［La／Ce］sh比值的变化，表明早中新世温度、南极底层流及氧化还原条件经历了3个变化旋回。 |
| 关键词: 稀土元素 地球化学 沉积物 古海洋环境 太平洋东部 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助，49070263号 |
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| THE REE GEOCHEMISTRY OF SEDIMENTS IN CORE CC48 FROM THE EAST PACIFIC OCEAN |
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Liu Jihua, Zhang Lijie, Liang Hongfeng
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Institute of Marine Geology, Ministry of Geology and Mineral Resources, Qingdao 266071
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| Abstract: |
| The studies of the REE geochemistry of sediments of core CC48 taken from the East Pacific Ocean, revealed that (1) Vertically downward, the sediments of core CC48 change from pelagic clay to siliceous ooze to calcareous ooze to silicalcareous ooze. The REE contents were distinct in different types of sediments. Clay had the highest REE concentration, calcareous ooze the lowest. There were strong relationships between the REE contents and authigenic minerals such as smectite, phillipsite and barite and detrital plagioclase and biogenic amorphous SiO2, CaCO3. They, except CaCO3, have major roles in REE enrichment. (2) The sharp changes of the REE contents in depth divided core CC48 into 5 layers that provided information for deep sea stratigraphic division. (3) The REE fractionation such as negative Ce anomaly, Eu anomaly and the fractionation between light REE and heavy REE (La/Lu) sh show that three types of sedimentary environments existed since early Miocene (above CCD, below CCD and near CCD). The Ce depletion (La/Ce)sh showed that, in early Miocene, sedimentary redox conditions changed in three cycles that reflect the cyclic changing of paleoclimate and the effects of AABW. |
| Key words: Rare earth element, Geochemistry, Sediment, Paleoceano-graphic environment, East Pacific Ocean |
