Zircon U-Pb Age of the Meta-rhyolite of Huangyakou Lead-zinc Deposit and Its Geological Significance in Yuzhong County, Gansu Province

Huangyakou lead-zinc deposit is located outside Baiyin orefield,being the main prospecting mining areas. Its metallogenic characteristics have long been considered to be similar to that of Xiaotieshan lead-zinc deposit. Through the LA-ICP-MS zircon U-Pb isotope dating of the meta-acid volcanic rocks in Huangyakou lead-zinc deposit,the age of meta-rhyolite is(507.6±1.8) Ma (MSWD=0.23, Points=23), belonging to the Middle Cambrian.This is also the formation age of Huangyakou lead-zinc deposit.On the basis of previous research,it is held that Baiyin copper polymetallic ore is formed in (467.1±2.2)-(465.0±3.7) Ma which belongs to the Middle Ordovician.There for,Huangyakou lead-zinc deposit was formed earlier than Baiyin copper polymetallic ore.It is proposed that Baiyin copper polymetallic orefield and its periphery are multi-stage metallogenic, which has some implications in the prospecting of the Baiyin orefield.