西昆仑帕米尔式铁矿床膏铁建造成因探讨——以老并铁矿为例

Genesis of gypsolyte-iron formation of West Kunlun-Pamir type iron deposits:a case study of Laobing iron deposit

产于塔什库尔干陆块下古生界含铁岩系的西昆仑帕米尔式铁矿床具有独特的膏铁建造特征。老并矿区具有明显的6个沉积铁矿化层,由下往上构成"粗碎屑岩-中基性火山岩夹层-磁铁矿层-含铁膏岩层-细碎屑岩"退积正粒序组合的沉积层,与火山活动关系密切,成矿物质主要来源于火山物质。在海底火山喷发过程中,深部火山岩浆与海水硫酸盐矿物发生混染作用,含铁热水溶液与膏岩层作用。随着温度、压力、pH值等环境条件的转变,先后结晶出硬石膏、磁铁矿、黄铁矿并沉积形成不同矿物组合的膏铁建造。

West Kunlun Pamir type iron deposits occur in the ferruginous rock series of lower Paleozoic erathem Taxkorgan Landmass and have unique characteristics of gypsolyte-iron formation.Laobing mining area has 6 obvious sedimentary iron mineralized layers,and has a sedimentary formation of retrograding normally graded sequence combination of “coarse clastic rock-intermediate basic volcanic interlayer-magnetite layer-fer-ruginous gypsolyte-fine grained clastic rock”.The area has a close relationship with volcanic activities,and the ore-forming materials derive from volcanic matters.In the course of submarine volcanic eruption,con-tamination takes place between the deep seated volcanic magma and the seawater sulfate minerals,and ferru-ginous hydrothermal solution interacts with gypsolyte.Along with the changes of the environmental condi-tions such as temperature,pressure and pH value,minerals like anhydrite,magnetite and pyrite are crystal-lized in succession and through sedimentation form a gypsolyte-iron formation of different mineral combina-tions.