Ore-control Structure-fluid-metallogenesis Of Dazhuangzi Gold Deposit

Dazhuangzi gold ore deposit is a large one that has been discovered recently. It is hosted in the Jingshan group strata that between Jiaobei terrane and Jiaolai basin. Ore types of the Dazhuangzi gold ore deposit include altered rock and quartz vein type.By contrasting the sources of ore-forming materials as well as the location of ore bodies towards the magmatic rocks and the ore-control structures of Dazhuangzi with that of Jiaojia, Linglong and Majiayao gold ore deposit, it can be concluded that sources of ore-forming materials in Dazhuangzi gold ore deposit is of multi-sources containing crustal material and layers of Jingshan. Moreover, the wall rock of Dazhuangzi gold deposit is quite different from the others;therefore, it is concluded as Dazhuangzi type gold ore deposit.Dazhuangzi gold ore deposit is controlled by a ductile-brittle shear zone, where the former ductile shearing was supervision by later brittle shearing. The ductile-brittle shearing effect accelerated the enrichment of Au element and controlled the occurrence of gold ore bodies. These lately brittle fractures can be divided into three groups, NNE, NE and EW trending according to the direction of them.The most important structures are the NNE trending faults which can be sub-divided into two classes: low dipping and high dipping ones. The former faults control the large â… ₁ ore bodies and the later faults control â…¡₁-â…¡₄ ore bodies. The two classes of faults presented a "λ" shape in the profile. While NE brittle fractures control the aurous quartz veins. On the contrary, EW brittle fractures formed after mineralization and destroyed the existing ore bodies, especially have a notably contribution to the movement of â… ₁ ore body in space.Analysis of rare earth element, sulfur isotopes, carbon and oxygen isotopes of the carbonate, H and O isotopes of fluid inclusions in quartz indicated that, ore-forming fluids have multi-sources, which are magmatic, metamorphic and meteoric water. And the ore-forming materials come from both earth's crust and Jingshan group. Studies on the relations of ore-forming fluids with altered rock, structures and mineralization suggested that ore-forming fluids are very important in the formation of Dazhuangzi type of hydrothermal deposits.According to the comparison of mineralization zoning laws of Dazhuangzi gold ore deposit with other well-known gold ore deposits in Jiaodong region and the lower temperature mineralizing conditions in Dazhuangzi, the author perform that there are still more reservoirs in the deep of the Dazhuangzi gold mine. By a large-scale mapping of tectonic deformation and rock facies features carried out in the mine area well as well as comprehensive analysis of the structure features, the author presented the forecast zone that the deposits formed in the north of structure F₁, which will receive well economic benefits.