我国沥青中的稀土元素分布及其环境意义

用中子活化方法测试了我国１８个沥青样品中的稀土元素分布，沥青的稀土元素球粒陨石标准化分布模式，铕异常及某些具有指相性元素对的比值（如Ｌａ／Ｃｅ，Ｌａ／Ｓｍ和Ｌａ／Ｙｂ），并且与现代不同岩相生物稀土元素分布模式进行对比表明我国沥青中的稀土元素分布具有以下特点：（１）东部二叠和第三系滨海相沥青，富含轻稀土元素，弱铕亏损；（２）西部三叠－株罗系海相沥青，富含重稀土，强铕亏损；（３）泥盆系以前远离陆地海相

REE ABUNDANCE DISTRIBUTION PATTERN OF BITUMEN IN CHINA AND THEIR ENVIRONMENTAL IMPLICATIONS

REE abundance of 18 bitumen samples has been determined by Neutron Activation Analysis.Based on the comparison of chondrite-normalized REE abundance distribution pattern, Eu anomaly and ratios of paired facies-index elements with those of living organism from different modern lithofacies, the bitumen occurring in China has such characteristics as following:(a)the bitumen from Permian and Tertiary littoral facies of eastern China is rich in LREE, with weak Eu depletion;(b) the bitumen from Triassic and Jurassic marine facies of western China, rich in HREE,with strong Eu depletion;(c)the bitumen from the land-far marine facies older than Devonian, rich in Eu, Yb and Lu; (d) the hydrothermal solutionreformed bitumen is rich in Eu and Nd. The paper also presents discussion on the difference of La/Ce ratio between the oil bitumen formed at depth and the coal-formed oil bitumen.It is shown that the variation of the former (0.20-1.89) is greater than the latter (0.53-0.65),indicating that the environment for the formation of bitumen is more complicated than that of coal.