Transpression in an Archean greenstone belt, northern Minnesota

摘要: Weakly metamorphosed Archean sedimentary and volcanic rocks of the Vermilion district, northern Minnesota, occupy an east–west-trending belt between gneisses granitic complex to north Giants Range batholith south. All measured strain, a foliation, mineral lineation in this are attributed "main" phase deformation (D2). Foliation strikes parallel dips steeply, plunges moderately steeply east or west is maximum stretching direction, X, subparallel fold hinges. An earlier, possibly nappe-forming, event (D1) left little evidence fabric district.A number features indicate that D2 involved significant component dextral strike-slip shear addition north–south compression. They include ductile zones with sigmoidal foliation patterns, bands, asymmetric pressure shadows, fact asymmetry F2 folds pred...