南海北部陆坡高速堆积体沉积物稀土元素特征及其物源意义

RARE EARTH ELEMENTS CHARACTERISTICS OF SEDIMENTS FROM HIGH-DEPOSITION-RATE SEDIMENT IN THE NORTH SLOPE OF SOUTH CHINA SEA AND ITS PROVENANCE SIGNIFICANCE

对南海北部陆坡MD05-2905站9个沉积物样品稀土元素进行分析,结果显示MD05-2905站沉积物中稀土含量总量(ΣREE)变化范围较大,其分布范围为60.66×10-6～350.37×10-6,平均值为174.59×10-6,其中全新世样品的稀土含量总量明显低于末次冰期样品,其球粒陨石分布模式与上地壳基本一致。对比发现,其ΣREE平均值相对接近中国黄土和珠江口,而与深海粘土中稀土元素的丰度相差较大,说明其主体可能来自陆源。稀土元素分馏参数δEu和δCe以及富集因子(EF)和判别函数(DF)揭示南海北部MD05-2905站沉积物与黄土、珠江口和台湾浅滩都有联系,显示了多物源多传输方式的特征。另外发现富集因子(EF)和判别函数(DF)数值在末次冰期时期与全新世时期差别相对较大,末次冰期时期黄土、珠江口和台湾浅滩的DF值都远远小于全新世时期,这可能反映末次冰期时黄土、珠江口和台湾浅滩对南海北部的物源贡献更大,也反映末次冰期与全新世期间各个物源供给/传输方式可能发生变化。

Study of rare earth element content of 9 sediment samples from core MD05-2905 in the northern slope of South China Sea showed that the total content of rare earth elements changed in a wide distribution range of 60. 66 ×10-6～350.37×10-6 with an average of 174.59×10-6 ,and the ZREE content of Holocene samples were significantly lower than the content of gla- cial samples. Their chondrite distribution patterns were consistent with the upper crust. Compared with published data in adjacent area,it was found that the average of E, REE content of site MD05- 2905 was relatively close to the data of sediments from the China loess and Pearl River estuary, and it varied greatly with an abundance of rare earth elements of deep-sea clay, and it might be- long to mainly land-based material sources. ment factor （EF） and discriminant function 2905 might be related to sediments of China REE fractionation parameters 3Eu and aCe, enrich- （DF）,illustrated that the material source of MD05- loess, the Pearl River estuary and the Taiwan shallow bank,showing multi-source and multi-transmission features. In addition,enrichment factor （EF） and the discrimination function （DF） values of last glacial samples displayed a relatively large difference with that of Holocene samples. DF value with sediments of Chinese loess, Pearl River estuary and Taiwan shallow bank during the last glacial period were far less than that during the Holocene,reflecting that Chinese loess,Pearl River estuary and Taiwan shallow bank during the last glacial period contributed more materials to northern slope of South China Sea than that dur- ing the Holocene,and each source supply/transmission mode may be changed from last glacial pe- riod to Holocene period.