地质科学2025，Vol.60Issue(4)：960-974,15.DOI:10.12017/dzkx.2025.064
二连盆地北缘勃勒金韧性剪切带40Ar/39Ar年龄及其构造意义
40Ar/39Ar ages of the Bolekin ductile shear zone in the northern margin of the Erlian Basin and their tectonic significance
摘要
Abstract
The Bolekin ductile shear zone,identified in the northern margin of the Erlian Basin,Inner Mongolia,is a structural feature of the Chagan Obo-Arongqi fault in northern Sonid Zuoqi.The shear zone trends nearly east-west and is developed within the Carboniferous intermediate-acidic volcanic rocks of the Baoligaomiao Formation,Permian biotite monzogranite,and their contact zones.The ductile deformation in this shear zone is intense,with well-developed macroscopic and microscopic structures such as mylonitic foliation,stretching lineation,S-C fabrics,asymmetric folds,rotated porphyroclasts,book-shelf structures,and mica fish.Field investigations indicate that the Bolekin ductile shear zone underwent two phases of ductile deformation with different characteristics.The early phase was characterized by north-to-south thrust-type ductile shearing under a compressional regime,while the late phase was marked by layer-parallel ductile shearing under an extensional regime.40Ar/39Ar isotopic dating was conducted on the muscovite-quartz schist from the strongly deformed zone within the shear zone,yielding plateau ages and isochron ages of 133.8～132.5 Ma,which indicates that the late-stage layer-parallel ductile shearing occurred during the Early Cretaceous.Based on regional data analysis,it is suggested that the late-stage layer-parallel ductile shearing of the Bolekin ductile shear zone was formed in an extensional tectonic setting during the Early Cretaceous,resulting from the collapse of the thickened lithosphere following the closure of the Mongol-Okhotsk Ocean.In contrast,the early thrust-type ductile shearing was a product of the subduction and closure of the paleo-Asian Ocean and the north-south collision between the North China and the Siberian plates during the Early Permian.The deformation characteristics and timing of the Bolekin ductile shear zone provide constraints on the tectonic evolution of the Chagan Obo-Arongqi fault since the Late Paleozoic.关键词
查干敖包—阿荣旗断裂/逆冲型韧性剪切/顺层韧性剪切/40Ar/39Ar年龄/二连盆地北缘Key words
Chagan Obo-Arongqi fault/Thrust-type ductile shearing/Layer-parallel ductile shearing/40Ar/39Ar age/Northern margin of the Erlian Basin分类
天文与地球科学引用本文复制引用
张祥信,雷世和..二连盆地北缘勃勒金韧性剪切带40Ar/39Ar年龄及其构造意义[J].地质科学,2025,60(4):960-974,15.基金项目
中国地质调查局地质调查项目(编号:1212011220458)资助 （编号:1212011220458）
