GEOLOGY AND GENESIS OF THE YONGXIN GOLD DEPOSIT IN HEILONGJIANG PROVINCE

The discovery of Yongxin gold deposit in Heilongjiang Province is a new geological prospecting achievement in the periphery of Duobaoshan ore-concentrated area. The deposit occurs in an area with small intrusive bodies or dykes of hypabyssal facies and subvolcanic rock facies, located in the contact zone of the Early Cretaceous volcanic basin and the Paleozoic mylonite. The sub-dacite and sub-rhyolite of subvolcanic rock facies, which formed before or during mineralization, were highly altered; while the granite-porphyry and dioritic porphyrite of hypabyssal facies, that formed after the mineralization, intruded into the ore bodies. The Au orebodies and mineralization are mainly hosted in the altered breccia, which formed from crypto-explosion, or in the mylonite in the periphery of altered breccia. The discovery of this deposit indicates the existence of the subvolcanic hydrothermal gold deposits that related to the Early Cretaceous volcanism in the Paleozoic mylonite zone in Western Heilongjiang Province. It also shows the prospecting potential in the periphery of Duobaoshan porphyry copper field.