Geochemistry of Neogene Mengtuo lignite in the Lincang from western Yunnan, southwestern China: Implications for its sediment material provenance and model of element enrichment

摘要

The Mengtuo Basin is proximal to the Bangmai Basin, which holds the world-class coal-hosted Ge deposit and shares the same sediment material provenance as the Lincang batholith. Herein, the mineralogy and geochem-istry of Neogene Mengtuo lignite were reanalyzed using supplementary data on major element oxides and minerals. The results indicated that Mengtuo lignite is a medium-ash lignite A. The minerals in lignite are composed of quartz, kaolinite, illite, chamosite, bassanite, and rutile. Compared to common Chinese coals, Mengtuo lignite is significantly enriched in Sb, Cs, and W, enriched in Rb and U, and slightly enriched in Be, As, Cd, Bi, and Th. The rare earth elements plus yttrium (REY) are characterized by significantly positive Ce and Gd anomalies and negative Eu anomalies. A positive Ce anomaly is inherited from the sediment source material. The local Lincang granite around the Mengtuo Basin dominates the mineralogy and geochemistry of lignite and carbonaceous mudstone. Because of the lack of hydrothermal fluids, an indispensable condition for Ge miner-alization in the Mengtuo Basin, a large-scale coal-hosted Ge deposit cannot be discovered.