Cherts from the Yangla copper deposit, western Yunnan Province: geochemical characteristics and relationship with massive sulfide mineralization

<正>Four layers of cherts were found for the first time in the Yangia copper deposit, western Yunnan Province. The cherts possessed the following geochemical characteristics: ① Low TiO2 and AI2O3 contents, but high ore-forming element (e.g. Cu, Au, Ag) contents; ② low total REE contents and clear negative Eu anomalies when normalized to chondrite similar to the REE contents and distribution patterns of associated massive sulfide ores; ③ silicon isotopic compositions of cherts in the Yangia deposit being the same as cherts and geyserite of hot-water sedimentary origin; ④ lead and sulfur isotopic compositions of cherts in the Yangia deposit being similar to those of the massive sulfide ores in the Yangia deposit; ⑤ Rb-Sr isochron age of cherts from the Yangia deposit being identical with that of host strata. Hence, we conclude that the cherts in the Yangia deposit are of hot-water sedimentary origin, which have a close relationship with the massive sulfide ores. The discovery of hydrothermal cherts from t