淮北煤田煤中镧系元素和钇的地球化学——“岩浆侵入对淮北花沟西煤中稀土元素分布的影响”的商榷

"岩浆侵入对淮北花沟西煤中稀土元素分布的影响"(高校地质学报,2013,19(4):671-676页)和"岩浆侵入对袁店二井煤矿72煤中稀土元素的影响"(煤炭工程,2014,46(5):119-122页)两文均表明"岩浆侵入致使煤中稀土元素含量增加,使煤中稀土元素发生了二次迁移与富集,且岩浆组分对煤中稀土元素的迁移富集具有一定程度的影响",而经重新整理原作者数据,并对其中镧系元素和钇(REY)的含量特征、上陆壳标准化分配模式的分析后,则得出完全不同的结论:淮北煤田煤中REY平均118mg/kg,天然焦中REY平均128mg/kg,侵入岩中REY平均326mg/kg;煤层侵入岩REY含量高于煤和天然焦,而煤和天然焦中REY含量无显著差别。煤层侵入岩上陆壳标准化的REY分配模式均显著富集LREY,且明显与煤和天然焦的REY分配模式不同,这表明岩浆侵入对煤中镧系元素和钇的影响甚微,且煤中的HREY较LREY和MREY富集。总结得出:对煤中稀土元素地球化学的研究须将钇元素一并分析,且将REY三分(LREY,MREY和HREY)便于更细致的对比;稀土元素分配模式标准化的参考应该尽量选择与煤近似的地质体(如北美页岩、上陆壳、中国煤等),不应均以球粒陨石为标准,方可更准确地解析稀土元素的来源及其在成煤及变质过程中的分异等。

Geochemistry of Lanthanide and Yttrium in Coals from the Huaibei Coalfield: A Discussion on Influence of Magmatic Intrusion on the Distrbution of REE in Coals at Western Huagou,Huaibei

Liu et al. (2013, 2014) concluded that the abundance of REE in coals was increased during igneous intrusion that caused a secondary migration and enrichment of REE. However, some completely different conclusions could be reached from the same data provided by original authors. The concentrations of REY in the unaltered coal, thermally-altered coal, and intrusive rocks from the Huaibei coalfield were 118, 128, and 326 mg/kg, respectively. There was no significant difference in the REY concentrations between unaltered coal and thermally-altered coal, both of which were much lower than those of intrusive rocks. With regard to the upper continental crust-normalized REY patterns, the unaltered coal and thermally-altered coal shared a similar pattern and obviously differed from that of intrusive rocks, suggesting that the REY in the Huaibei coals was not affected by igneous intrusion. The LREY was more concentrated than MREY and HREY in the intrusive rocks; whereas the HREY was more enriched in coals than LREY and MREY. Therefore, the geochemistry of REE and yttrium suggests that REY should be divided into LREY, MREY, and HREY. Moreover, a similar geologic body (i.e., North American Shale, Upper Continental Crust, and common Chinese coals) to coals may be chosen as a standard for REY normalization.