摘要
内蒙古大青山地区是华北克拉通北缘西段以孔兹岩系发育为特征的早前寒武纪变质杂岩发育地区之一。区内,除大面积出露的孔兹岩系之外,还残存有一套由各种石英岩、变粒岩组成的浅变质碎屑沉积地层,前人将其划归乌拉山岩群第四岩组或高角闪岩相孔兹岩系。笔者通过详细的地质填图,发现这套浅变质地层以角度不整合覆盖在孔兹岩系之上,应是孔兹岩系经历了下地壳麻粒岩相变质变形并隆升到地表之后沉积的,形成时代为古元古代,并把这套浅变质地层定名为美岱召岩群。
The Daqing Mountains area is one of the areas of early Precambrian khondalite-bearing meta-morphic complexes in the western segment of the northern margin of North China craton.In addition to the widely exposed khondalite series,there occurs a suite of low-grade metamorphic clastic rocks com-posed of various types quartzites and granulitite(leptite),which was previously assigned to the Fourth Formation-complex of the Archean Wulashan Group-complex or high amphi bolite-facies khondalite series.Through detail geo logical mapping and research,it is found that this suite of low-grade metamorphic stra-ta overlies the khondalite series unconformably and was not deposited until the khondalite series underwent granulite-facies metamorphism and deformation of the lower crust and was exhumed onto the surface.It is Paleoproterozoic in age and named the Meidaizhao Group-complex.
出处
《地质通报》
CAS
CSCD
北大核心
2003年第7期480-486,共7页
Geological Bulletin of China
基金
中国地质调查局内蒙古自治区土默特右旗6幅1:5万(J5.3.4)和包头地区1:25万(200113000021)区域地质调查项目。
关键词
古元古代
美岱召岩群
孔兹岩系
角度不整合
内蒙古大青山
Palaeoproterozoic
Meidaizhao Group complex
khondalite series
unconformity
Daqing Mountains area in Inner Mongolia
