Au-Ag MINERALIZATION AND PROSPECTING GUIDE IN QINGTIAN-XIAN JU AREA, ZHEJIANG PROVINCE

Qingtian-Xianju area is located in Wenzhou-Linhai depression,southeastern Zhejiang folded belt,South China folded system.The wall rocks of Au-Ag mineralization are crystal-vitric welded tuff of Xishantou formation,upper Jurassic.The main controlling structures are volcanic mechanism and related faults.Multiperiodic activities of volcanic eruption and magmatic intrusion offered heat,thermal fluid and mineralized materials to Au-Ag mineralization.The area is situated in abruplty changed belt of mantle gradient.The character of deep-seated structure in this area is the same as that in Longquan-Suichang Au-Ag mineralized belt.The activities of volcanic erupsion,magmatic intrusion and structure are frequent and strong in the area,accompanying obvious multiperiodic fluid activities.The basement rocks of the depression are metamorphosed auriferous rocks(Chencai group,etc.).The cap formation is volcanic eruption rocks which were formed in Mesozoic period and developed from basement metamorphic auriferous rocks through remelting or partly syntexics.Mineralization materials such as Au and Ag are subjected to activating,mingrating,enriching or re-distributing,with the development of basement rocks.Part of Au-Ag enrich in favorable structures to form ore bodies.thers are distributed in tuffaceous rocks in the form of naturlism and/or free absorption,then re-activated and remigrated depending on multiperiodic thermal fluid activity,and finally enriched in favorable structures to form ore bodies.Thus,Qingtian-Xianju area is a favorable area for Au-Ag mineralization.