TERRANE CHARACTER OF THE NORTHEAST MARGIN OF THE MOLDANUBIAN ZONE - THE KUTNA HORA CRYSTALLINE COMPLEX, BOHEMIAN MASSIF

Three major allochthonous units have been distinguished on the north-e astern border of the Moldanubian Zone, which differ each from other in lithology and structural and metamorphic evolution. Their present day position displays significant metamorphic and structural inversion re sulting from progressive nappe stacking during the Variscan orogeny. T he uppermost-Gfohl Unit consists of anatectic rocks containing high te mperature/high pressure relics, i.e. granulites, eclogites and garnet peridotites. The rocks of the Gfohl Unit were strongly mylonized durin g uplift and later also extensively migmatized in the kyanite stabilit y field. The Kourim Nappe is built up by a sequence of fine-grained le ucocratic migmatites with preserved relics of a pre-Variscan deformati on event. This event was terminated by the intrusion of coarse-grained porphyritic granites, converted into augen orthogneisses by the Varis can orogeny. The lowermost Micaschist Zone was formed from a sequence of metapelites intercalated with diopsidic amphibolites. During uplift from deep crustal zones the Gfohl Unit cut off a thick slice of the b asement crustal material represented by the Kourim Nappe. The quartzo- feldspathic material of the Kourim Nappe acted as a major shear interf ace because of its extreme ductility under the conditions found in the middle crust. This process occurred under amphibolite facies metamorp hism. The continuous uplift of the nappe pile induced another crustal segment in the nappe stack, represented by the Micaschist Zone. The wh ole nappe sequence was then thrust over the Moldanubian Zone. A westwa rd sense of shear is suggested for the whole uplift history. The kinem atic pattern was complicated by later strike-slip ductile faults which finished the recent geological configuration.