敦密断裂带走滑运动的^(40)Ar/^(39)Ar年代学证据  

^(40)Ar/^(39)Ar Geochronology Evidence of Strike-Slip Movement in Dunhua-Mishan Fault Zone

作　　者：孙晓猛[1] 刘永江[1] 孙庆春[1] 韩国卿[1] 王书琴[1] 王英德[1] 

机构地区：[1]吉林大学地球科学学院,长春130026

出　　处：《吉林大学学报（地球科学版）》2008年第6期965-972,共8页Journal of Jilin University：Earth Science Edition

基　　金：国家"973"项目(2009CB219305)

摘　　要：敦密断裂带是郯庐断裂带北段最重要的分支,其大规模左旋走滑剪切时代一直是悬而未决的科学问题。野外构造解析和显微构造分析表明,密山县知一镇附近的敦密韧性剪切带为左旋剪切带,变形温度约450~650℃。在韧性剪切带糜棱岩中获得黑云母单矿物的40Ar/36Ar-39Ar/36Ar等时线年龄值为(161±3)Ma,结合完达山地体的走滑拼贴时代,认为敦密断裂带在中侏罗世末期发生强烈的左旋走滑运动。这一年代学数据反映了在滨太平洋构造域构造活动期间,郯庐断裂被利用而再次发生左旋走滑,并向北扩展到东北地区。敦密断裂走滑运动时代与完达山地体的走滑-拼贴增生时代吻合,两者是相同大地构造背景中的产物。Dunhua- Mishan fault zone is the most important branch in the northern segment of Tancheng- Lujiang fault zone and its large scale of sinistral strike-slip shear age has been an unsolved scientific problem, The field structural and microstructural analyses suggest the Dunhua - Mishan ductile shear zone near Zhiyi Town, Mishan County is sinistral strike-slip shear zone , the deformational temperature of which is about 450℃ to 650℃. The biotite ^40Ar/^39Ar isoehron age, which is （161±3） Ma, was collected in the mylonite of ductile shear zones. If the age is combined with the age of Wandashan terrane strike-slip and matching accretion, it is considered that Dunhua - Mishan fault zone made the intense sinistral strike-slip movement in the last stage of J2. The isoehron age data show that the second left-lateral strike-slip age of Tancheng - Lujiang fault zone occurred during the period of tectonic movement in marginal-Pacific tectonic domain, It is also the age of Tancheng - Lujiang fault zone which stretches to the Northeast, China. The age of sinistral strike-slip movement of Dnnhua - Mishan fault zone is identical with the age of Wandashan terrane strike-slip and matching accretion, which indicates that both are the product with the same tectonic background.

关 键 词：郯庐断裂带 敦化-密山断裂带 韧性剪切带 糜棱岩 ^40Ar/^39Ar等时线年龄 

分 类 号：P542.3[天文地球—构造地质学]