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

Four layers of cherts were found for the first time in the Yangla copper de posit, western Yunnan Province. The cherts possessed the following geochemi cal characteristics: 1. Low TiO2 and Al2O3 contents, but high ore-forming e lement (e.g. Cu, Au, Ag) contents; 2. low total REE contents and clear nega tive Eu anomalies when normalized to chondrite similar to the REE contents and distribution patterns of associated massive sulfide ores; 3. silicon is otopic compositions of cherts in the Yangla deposit being the same as chert s and geyserite of hot-water sedimentary origin; 4. lead and sulfur isotopi c compositions of cherts in the Yangla deposit being similar to those of th e massive sulfide ores in the Yangla deposit; 5. Rb-Sr isochron age of cher ts from the Yangla deposit being identical with that of host strata. Hence, we conclude that the cherts in the Yangla deposit are of hot-water sedimen tary origin, which have a close relationship with the massive sulfide ores. The discovery of hydrothermal cherts from the Yangla copper deposit provid es further evidence for the hydrothermal exhalative origin of the massive s ulfide deposits.