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    高级变质区岩石地层系统建立的思考与实践——以内蒙古大青山—乌拉山地区为例

    Consideration and practice of the construction of litho stratigraphic systems in high-grade metamorphic terrains —Acase study in the Daqingshan-Wulashan area

    • 摘要: 提要:作者通过两个项目的区域地质调查研究,在大青山—乌拉山及其邻区重建了早前寒武纪地层系统,将新建的美岱召岩群列入古元古代。对区内高级变质岩石地层进行重组,在麻粒岩系中划分了2个岩组,归并为桑干岩群,将乌拉山岩群划分为上、下两个亚岩群,下亚岩群片麻岩系,上亚岩群相当于集宁群,可称孔兹岩系。提出本区高级变质区的主期构造是穹形构造与穹间褶皱群构造组合样式(简称“穹—褶”构造),确立了大型顺层滑脱构造系统是决定高级变质岩石地层空间分布、组成特征和相互关系的关键因素,提出了研究高级变质岩石地层系统建立的方法与步骤。

       

      Abstract: Abstract:The early Precambrian stratigraphic system in the Daqingshan-Wulashan area is reconstructed based on recent regional geological survey. A Meidaizhao Group-complex is eslatlished and classified as the Paleoproterozoic. The high-grade metamorphic rocks in the area are regrouped, i.e. the granulite sequence is subdivided into two formation complexes, which are merged into the Sanggan Group-complex, and the Wulashan Group-complex is subdivided into two subgroup-complex, a lower subgroup complex. and an upper subgroup complex.The former is known as the gneiss sequence and the latter is equivalent to the Jining Group, a khondalite sequence. The major structural patterns of the high-grade terrain in the area are characterized by dome structures and fold groups between the domes (simply called `dome-fold' structures). It is suggested that the large-scale ledding detachment system is a key factor for determining the spatial distrilution,composition and interrelations of high-grade metamorphic rocks.The new ways and methods of estallishing lithostatigraphic systems in high-grade metamorphic terrains are proposed in the paper.

       

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