内蒙古东部敖脑达坝铜-银-锡矿区附近发现晚石炭世地层

摘要

在内蒙古东部的大兴安岭中南段地区,具有工业价值的多数大中型银多金属矿床均产于二叠系中.笔者在敖脑达坝铜-银-锡矿床开展研究时,对该矿区西部出露的凝灰质板岩取样并开展了LA-MC-ICP-MS测年工作,获得的锆石U-Pb年龄为(302.6±1.9)Ma,MSWD=2.0,表明凝灰质板岩的原岩形成年代为晚石炭世,而不是前人认为的二叠纪.这一新发现可能对重新认识该区的区域地质演化具有重要意义.%Most economically important medium- to large-sized Ag-polymetallic deposits occurring in south-central part of the Da Hinggan Mountains in east Inner Mongolia are hosted by Permian strata. The LA-MC-ICP-MS dating of zircons from tuffaceous slate outcropped in the western part of the Aonaodaba Cu-Ag-Sn deposit yielded an U-Pb age of (302.6 + 1.9) Ma with MSWD being 2.0, which indicates that the original rock of the tuffaceous slate was formed in late Carboniferous instead of in Permian considered by previous researchers. This new discovery is of great significance for re-understanding the regional geological evolution.