GENESIS AND EVOLUTION OF THE DUCTILE DEFORMATIONAL BANDS IN DEEP TECTONIC FACIES IN THE ARCHAEAN HIGH GRADE METAMORPHIC AREA, EAST HEBEI
Sun Zhongshi Yang Zhensheng (Changchun College of Geology)
The banded structures in the Archaean gneiss area in East Hebei are well developed, They are the chief structural features of the ductile deformational bands in the deep tectonic structure facies (corresponding to granulite facies). They are divided, according to their genesis, into four major types, i. e. sedimentary band, metamorphic differentiated band (further subdividedinto four types, mechanical differentiated band, chemical differentiated band, partial melting band and emplacing band of rock body in solid-state), composite band and structural transposition band. Meanwhile,a study on constituting characteristics, formation evolution, and distinguishing marks of different genetic band is made, having a great significance in the research on characteristics of lower crustal structure.