The Characters and Mechanism of Yingbishan Gold Ore Deposit in the Volcanic Breccia Chimney

Yingbishan gold ore deposit is a volcanic hydrothermal deposit hosted in the volcanic breccias chimney whose occurrence is controlled by the nearly-transmeridional fracture F_1 in the ore field.The ore bodies are strictly confined within the fractured zones with different orientations in the pipe, and the nonhomogeneous gold mineralization mainly displayed the relationship between the mineralization and the intense silicatization as well as the fine-micro grained pyritization . From the middle of the pipe towards the marginal rim the ore-tenor exhibits the decreasing tendency implying that the mineralizing material sources have originated from the central parts of the pipe.In the term of the ore-forming process mechanism, the Jurassic period volcanic rocks (K1y)invaded along the hanging wall of the incipient fracture F1(conducting structures) and formed the breccias chimney, and the later stage auric volcanic hydrothermal fluids filled the tensional fractures (host structures)in the pipe finally yielded this volcanic hydrothermal gold ore deposit.