新疆塔什库尔干地区“帕米尔式”铁矿床的发现及其地质意义

The discovery of the “Pamir-type” iron deposits in Taxkorgan area of Xinjiang and its geological significance

新疆塔什库尔干地区近年来发现了一系列规模较大的铁矿床,如老并铁矿床、乔普卡里莫铁矿床、叶里克铁矿床、吉尔铁克沟铁矿床等。由于这些矿床具有较为独特的矿床地质特征和成矿时代特点而有别于世界上已知的铁矿床,因而将其命名为"帕米尔式"铁矿床。以老并铁矿床为例对"帕米尔式"铁矿床的地质特征、成矿年代、矿床成因等进行了初步研究。研究表明,"帕米尔式"铁矿床主要赋存于布伦阔勒岩群黑云石英片岩岩性段内,该岩性段磁铁矿化现象较为普遍,普遍发育磁铁矿、黄铁矿、石膏、硬石膏的矿物同生组合,为一种特殊的膏铁建造;LA-ICP-MS碎屑锆石U-Pb同位素测年表明,含铁建造布伦阔勒岩群的形成时代为早古生代;矿床成因类型为海相火山沉积型磁铁矿矿床,后期受到一定的区域变质作用的叠加改造。该类型矿床的发现,对于丰富世界铁矿床的类型和同类型铁矿床的找矿工作都具有重要的借鉴意义。

A series of relatively large-size magnetite deposits have been discovered in Taxkorgan area of western Kunlun,Xinjiang,e.g.,Laobing iron deposit,Qiaopukalimo iron deposit,Yelike iron deposit and Jiertiekegou iron deposit.Because these deposits have unique geological features and metallogenic epoch,the authors name them ＂Pamir-type＂ iron deposits as a new type of iron deposit in the world.With the Laobing iron deposit as an example,the authors studied geological features,metallogenic epoch and genesis of this kind of ore deposit,and the results show that the ore deposit occurs in biotite quartz schist of Bulunkuole Group,where magnetite mineralization is extensively developed with the syngenetic combination of magnetite-pyrite-gypsum-anhydrite,which constitutes a special anhydrite-gypsum-iron formation.LA-ICP-MS U-Pb isotopic dating of detrital zircon shows that iron formation of Bulunkuole Group was formed in early Paleozoic period,and the ore deposit was genetically of marine volcanic sedimentary magnetite type subjected to later superimposed reformation of some regional metamorphism.The discovery of the new iron deposit type has important reference significance in enriching types of iron deposits and prospecting for the same type of iron deposits all over the world.