Syn-tectonic magmatic emplacement in Wanda Mountain, northeast China: A response to the Late Mesozoic sinistral strike slip motion

Raohe granitic plutons in Wandashan, northeast China show evidence of syn-tectonic magmatic emplacement. The dark minerals and K-feldspar phenocrysts are aligned parallel to the NNE-trending magmatic flow lineation. The lenticular dioritic xenoliths are arranged horizontally, characterized by long axis parallel to the magmatic flow lineation with sinistral shearing. Boudin quartz veins are also well developed in the plutons. All of these features indicate that the plutons were affected by sinistral strike-slip shearing in the process of magmatic intrusion and emplacement. Thus, the Raohe granite was formed in a sinistral strike slip environment which underwent syn-tectonic magmatic flow. The Raohe granite was emplaced at 121±1Ma and 119±1Ma, as shown by LA-ICP-MS zircon U-Pb dating. The wall rock gabbro and the syenite veins and diabase dikes that intruded in the Raohe pluton were analyzed by zircon U-Pb dating, with the yielded ages being 160±1Ma, 109±2Ma and 124±1Ma, respectively. According to the characteristics of inherited zircon age data in these samples, the ages of wall rock gabbro are quite concentrated with no relict zircon ages, whereas the granite and the dikes have inherited zircon age data from Archean to Jurassic. These age data combined with the regional geology might indicate that the Wandashan block had completed the subduction collage before 120Ma, and the Wandashan granitic plutons were formed in sinistral strike slip motion of intracontinental deformation as the syn-tectonic emplacement.