青田-仙居地区金银矿化特征及找矿远景分析

AuAg MINERALIZATION AND PROSPECTING GUIDE IN QINGTIANXIANJU AREA,ZHEJIANG PROVINCE

浙江青田－仙居地区位于华南褶皱系浙东南褶皱带之温州－临海拗陷内．金银矿化的直接围岩是上侏罗统西山头组晶屑、玻屑熔结凝灰岩．主控矿构造为火山机构及有关的断裂构造．多期次的火山活动、岩浆侵入活动为金银成矿提供热源、热液及成矿物质来源．该区与龙泉遂昌金银成矿带同处于地幔陡变带内，深部构造特征相同或相似．区内构造活动、火山喷发及岩浆侵入频繁而强烈，伴随的多期次热液活动明显．基底岩系为含金变质岩系（陈蔡群、龙泉群），盖层岩系是由基底含金变质岩系重熔或部分同熔形成的中生代火山喷发－沉积岩系．在基底岩系演化过程中，金银等成矿物质发生了活化、迁移、富集或再分配作用，部分在构造有利部位富集成矿，部分则以自然态、游离吸附态赋存在凝灰质岩石中，经多期次热液作用再次被活化、迁移，最终在成矿有利部位沉淀富集成矿．因此，青田－仙居地区具备较好的金银成矿条件，是金银矿找矿的良好远景区．

ingtian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