内蒙古大青山煤田晚古生代沉积砾岩的物源分析

Analysis of Late Paleozoic Conglomerates from Daqing Mountain in Inner Mongolia

大青山煤田晚古生代沉积岩层中共有 1 4个砾岩层。通过岩矿鉴定、重矿物对比分析、砾度测量及不同成分砾石含量统计、K- Ar同位素年龄分析及 REE配分模式对比研究。证明晚石炭世早期及早二叠世早期砾岩主要砾石成分是石英砂岩 ,物源为下伏奥陶系石英砂岩 ;早二叠世中期砾岩主要砾石为石英岩砾石 ,母岩为震旦纪石英岩 ;早二叠世晚期及晚二叠世初期砾岩的砾石成分主要为中酸性火山岩砾石 ,并含有一定量的太古界变质岩砾石 ,母岩分别相当于盆地以北岛弧或活动大陆边缘的华力西中晚期火山岩和太古代变质岩。陆源区并不是自元古代以来长期隆起的“阴山古陆”,而是研究区北部华力西期构造岩浆隆起区。

There exist 14 sedimentogenic conglomerates of late Paleozoic sedimentary layer in Daqingshan coalfield.Based on the study of the petrology and comparing analysis of heavy minerals,granulometric analysis and percentage statistics of different composition gravels, K Ar isotopic age determination ,the comparison of REE distribution,it is probed that the main pebbles of conglomerates formed in the earlier period of Upper Carboniferous and Lower Permian are the quartzose sandstone gravels,coming from Ordovician period quartzose sandstone.The essential pebbles of conglomerates formed in the middle of Lower Permian are the quartzite gravels,their parent rock is Sinian Period quartzite .The conglomerates formed in the later period of Lower Permian and initial Stage of Upper Permian consist mainly of neutral acidic volcanics and metamorphic rock peddles of certain quantity.The mother rock of gravels are separately equal to the Variscan volcanics of island arc or activity continental margin and Archean era metamorphic rocks.The land source area is not Yinshan Ancient Land of long term uplift from Proterozoic era,but the upwelling area of Variscan tectonomagmatic activities in Inner Mongolia on the northern of the studed area.