Deformation Fabrics and Rheological Features of Early Permian Fanjiatun Formation from Quannongshan Area,Southeastern Changchun
Liang Chenyue
Liu Yongjiang
Zhu Jianjiang
Li Weimin
Chang Ruihong
Zhang Li
Abstract：The Quannongshan area is located in the southeastern part of Changchun,at the junction of the Jiamusi-Yilan fault belt and Xar Moron suture zone.Detailed field observations indicate strong ductile deformation event which developed in these mylonites:Lower Permian Fanjiatun Formation (P1 f )calc-mylonites and the intrusive Yanshanian granitic mylonites.Most rocks were deformed to protomylonites and mylonites macroscopically in a gneissic-like structure.The major strain type is plan-strain and marked by much compression,which is general compression.And the deformed rocks are characterized by L=S type tectonites demonstrating a strong tectonic condition of a compressive ductile shear zone.A variety of macro/micro-ductile de-formation kinematic marks indicate a significant sinistral shearing.Based on detailed macro/microstructural analysis,quartz c- axis EBSD fabrics,calcite-dolomite geothermometer from electron probe,calcite < e> twin morphology and quartz/feldspar deformation behaviors,a low-temperature plastic flow characteristics and greenschist metamorphic environment were esti-mated.The ductile shear zone has a relatively high strain rate,which is between 10 -6 .95 and 10 -8.89 in a highly strained zone and 10 -9 .25 -10 -12.17 away from the strong deformation zone.The lower limit of the differential stress during the mylonization process should be approximately 51.27-65.46 MPa,which represents that the mylonitization formed at a slightly faster strain rate with low deformation temperature and moderate strain strength.In the initial deformation period,the pressolution diffu-sion and the twin gliding are the main deformation mechanisms,then in the middle of the deformation they are dominated by the twin gliding and the grain boundary slip.In the late stage of the progressive deformation,the grain boundary sliding oc-curred in parts of strong stain zone.The formation of this ductile shear zone might be related to the Izanagi plate obliquely NNW subducting under the Eurasia plate during the middle and late Early Cretaceous,which is a local performance of the sinis-tral strike-slip Jia-Yi fault.
Keywords：structural deformationEBSDdeformation temperaturepaleo-stressstrain rateJia-Yi faulttectonics
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：19( 2174-2192 )