云南省临沧市勐托新近系褐煤的微量元素地球化学特征

Geochemistry of trace elements in the Mengtuo Neogene lignite of Lincang,western Yunnan

为研究云南临沧勐托新近系褐煤的微量元素地球化学特征,共采集了11个褐煤样品,采用ICP-MS和ICP-CCT-MS（As和Se）对煤中微量元素进行了测试。结果表明：与中国煤相比,勐托褐煤中Rb（96.1mg/kg）、Sb（15.3mg/kg）和Cs（25.9mg/kg）显著富集,W（10.6 mg/kg）和U（20.2 mg/kg）富集,Be（7.84 mg/kg）、Ga（16.1mg/kg）、As（11.6mg/kg）、Cd（0.67mg/kg）、Sn（6.66mg/kg）、Pb（34.6mg/kg）、Bi（3.86mg/kg）和Th（28.2mg/kg）稍富集,微量元素组成与大寨富锗煤不同,与酸性花岗岩物源供应有关。勐托褐煤中REY含量范围为121~420mg/kg,平均251mg/kg,均较大寨富锗褐煤高,且以Ce显著正异常和Eu显著负异常为特征,明显区别于大寨褐煤,Eu负异常和上陆壳标准化的REY分配模式均表明勐托褐煤中稀土元素受盆地周边花岗岩风化陆源碎屑供应影响。

To investigate the geochemical characteristics of trace elements in the Mengtuo Neogene lignite of Lincang in western Yunnan, a total of 11 lignite samples were collected, and the trace elements were determined by ICP-MS and ICP-CCT-MS（As and Se）. Results indicated that the enriched trace elements were different from the Dazhai Ge-rich coals, i. e. , significant enrichment of Rb（96. 1 mg/kg）, Sb（15. 3 mg/kg） and Cs（25. 9 rng/k_g）, enrichment of W（10. 6 rng/kg） and U（20. 2 rng/k4g）, and slight enrichment of t3e（7. 84 rng/kg）, Ga（16. 1 mg/kg）, As（11.6 mg/kg）, Cd（0. 67 rng/kg）, Sn（6. 66 rng/kg）, Pb（34. 6 mg/kg）, Bi（3. 86 mg/kg） and Th（28. 2 mg/kg） when compared to common Chinese coals, which might be inherited from the weathered granite around coal-accumulating basin. The REY concentrations in Mengtuo lignite range from 121 mg/kg to 420 mg/kg, with an average of 251 mg/kg, higher than that of Chinese coals. The UCC-normalized REY distribution patterns of Mengtuo lignite are characterized by the significant positive Ce anomaly and negative Eu anomaly, obviously differentiating from that of Dazhai coals, suggesting a terrigenous input of REY from weathered granite.