Geological Characteristics and Genesis of the Najihe Pb-Zn-Ag Deposit in Elunchun County,Inner Mongolia Province

The Najihe Pb-Zn-Ag deposit,located in the northern section of the Da Hinggan Ling metallogenic belt,has ore reserves of mid-scale at present as one of the few exploration results in recent years. The ore bodies are gently sloped lenticular and stratiod,controlled by fractures within strata and hosted by upper Jurassic rhyolite,volcanic clastic rocks and andesite. The ineralizaiton fluids were originated from the late volcanism and atmospheric water in the late stage. Metallogenic materials were mainly from mantle and partly extracted from ancient strata. It was formed in the mid-late Yanshanian in accord with the Mesozoic large-scale mineralization event in East China. This deposit is a mid-low temperature hydrothermal one associated with midacid magma intrusion. Silver mineralization with Ag grade of several thousands of ppm was found near this deposit,implying a hope to find a single Ag deposit and porphyry ore deposit in the deep subsurface of this district.