Abstract:

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.

Key words: lanthanide, yttrium, geochemistry, coal, Huaibei coalfield