新疆西天山阿吾拉勒东段铁矿成矿时代与赋矿地层厘定

摘要

10 large and medium-sized iron ore deposits have been found in Awulale iron ore metallogenic belt,it be-comes the only one in ten iron ore resource bases in China.All the researchers believe that these are volcanic-type iron ore which belong to the same age of ore-bearing strata.The ore-bearing layer zektai formation of Shikebutai iron ore con-tains Fusulinid sp.fossils, which are proved to belong to the early times of late Caboniferous.The volcanic rock isotopic age of 313~317Ma fatherly shows that this belongs to the Bashkirian period;and the volcanic rock isotopic age of 321 Ma in Chagannur iron rock proves that ore metallogenic epoch is the late stage of the Early Caboniferous Serpukhov pe-riod. the Shikebutai in west Tianshan region belongs to Bashkirian period,the Kumutage siderite deposit in east Tianshan region.The ore-bearing strata in the east section Awulale iron ore belt belongs to Hoff period.Threrfore,the name“Duha-lajunshan Formation”which belongs to Tournaisian Age can’t be used to this layer. New name of geolith should be cre-ated for the volcanic rock strata.%西天山阿吾拉勒铁矿成矿带发现大、中型铁矿床10处，为近年来我国新发现的十大资源接替基地中唯一铁矿资源接替基地。该带火山岩型铁矿床研究程度较低，成矿时代和赋矿地层层位认识混乱。在已有研究成果基础上，结合笔者多年地层研究成果，认为该区铁矿存在两个成矿期及赋矿层位，即晚石炭世早期（313~317 Ma±）巴什基尔期和早石炭世晚期（321 Ma±）谢尔普霍夫期。前者包括式可布台铁矿，赋矿地层为则克台组；后者包括查岗诺尔铁矿、备战铁矿等，其赋矿火山岩系地层被多数研究者称为大哈拉军山组。据生物地层和同位素测年成果，该地层层位和时代相当于阿克沙克组上亚组，但二者岩性迥异。其与大哈拉军山组为年代相差约30 Ma的不同层位，区域上两组间呈角度不整合接触关系。因此，建议对该赋矿地层创建新的地层单元名称。