The Saint-Fulgence Lobe, located southest of the Lac-Saint-Jean Anorthosite, is hosted by a thin strip of banded gneisses of variable composition. On the eastern portion of the lobe, the banded gneisses are in contact with a charnockitic gneiss. A mangeritic intrusion fringes its western border. Structural and microtextural relationships along the eastern border indicate the emplacement of the anorthosite through diapiric rise. On the other hand, tectonic relationships on the western limits

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... ot be as easily explained through a simple diapiric rise of the intrusive masses, anorthositic and mangeritic, thus other possible mechanisms must be considered. Three microtextural assemblages can be recognized within the rocks from the western border: 1) a non-oriented fabric, 2) an early oriented fabric and 3) a late oriented fabric. The first group is recurrent in the intrusive rocks (anorthosite and mangerite). These microtextures lack orientation and may correspond to an early deformational phase which took place at a great depth following diapiric rise. The second group can be found within the anorthosite. These microtextures are oriented and are associated to abruptly plunging lineations. They are product of relative shearing between the elements of the anorthosite mass, following diapiric rise. The third group is the last one to appear. These microtextures are characterized by a well developped oriented fabric and are associated to strongly dipping foliations, generally striking N-S with sub-horizontal to weakly plunging lineations. They are mostly evident in the gneissic series and less so in the anorthosite and the mangerite.