Abstract: The petrochemical and trace element and rare earth element geochemical features of brittle ductile tectonite were studied during the 1∶50 000 scale regional geological survey of the Huangcai Sheet.The study indicates that,when medium fine grained porphyritic two mica monzonitic granites are modified into mylonitized granite,protomylonite,sericite mylonite,silicified mylonite,phyllonite and mylonite schist,their chemical composition changes to different degrees.The dispersion,accumulation or stability of chemical elements are controlled not only by the protoliths （inheritance）but also by the deformation intensity of the composition, properties and mobility of the fluids（variability）.