欧龙布鲁克地块西段达肯大坂岩群物质组成及变形特征研究

达肯大坂岩群是欧龙布鲁克地块结晶基底的重要组成部分,在形成过程中保存了丰富的物质记录和演化信息,是研究欧龙布鲁克地块乃至我国西部古老地壳及构造演化的窗口。通过对达肯大坂岩群详细的物质组成及构造剖面研究,根据岩石组合及变质—变形特征,将其进一步细化为混合片麻岩岩段、(混合岩化)流变片麻岩岩段、条带状片麻岩岩段、片岩岩段和大理岩岩段,野外调查表明,达肯大坂岩群中发育多期构造变形作用,根据野外变形特征及各期变形的叠加改造关系,初步建立了达肯大坂岩群相对变形序列,为区域构造过程的探讨与对比提供了新的基础资料。

The material composition and deformation characteristics of Dakendaban Rock Group,in western Oulongbuluke micro-block,north to Lenghu in Qinghai Province

Dakendaban Rock Group,as an important component of the crystalline basement of the Oulongbuluke block,preserved the richest material record and evolutional information during its formation,which may provide us a window to explore the ancient crust and the tectonic evolution of the Oulongbuluke block,even of the west of China.Based on the 1:50000 regional geological surveys,we investigated in detail the rock assemblage and the metamorphic-deformational features by structural profiles and microscope.According to the rock assemblage and the metamorphic-deformational features,we further refined the Dakendaban Rock Group into 5 rock segments:compound gneiss rock segment,(migmatization)rheological gneiss rock segment,banded gneiss rock segment,schist rock segment and marble rock segment.The field investigation and structural analysis proved that the Dakendaban Rock Group underwent multiple phases of deformation.From the field deformation characteristics and superposition relations of each phase,we initially established the relative deformation sequence,which provides a new foundation for the study and comparison of the regional tectonic processes.