Structure of the Deep Freeze Range-Eisenhower Range of the Wilson Terrane (North Victoria Land, Antarctica): emplacement of magmatic intrusions in the Early Palaeozoic deformed margin of the East Antarctic Craton

In North Victoria Land (Antarctica), the Wilson Terrane is a portion of the palaeomargin of the East Antarctic Craton, deformed during the Late Cambri an-Early Ordovician Ross Orogeny. Crustal deformation, from westward subduc tion of the palaeo Pacific plate and terrane accretion on this palaeomargin , gave rise to the development of a transpressive fold belt and a wide magm atic are. In the inner portion of the Wilson Terrane, (Deep Freeze Range-Ei senhower Range) a large portion of this magmatic are is made up of intrusio ns and dyke systems. Intrusive rocks range from large unfoliated plutons to well foliated sheet intrusions emplaced in low and medium-high grade metam orphic rocks respectively. Field and structural data on intrusive rocks and metamorphic host rocks, coupled with parameters relative to deformation me chanism and magmatic processes (crystallization and cooling) rates, make it possible to outline an episode of diffuse synkinematic magmatism in the Wi lson Terrane. The emplacement of intrusions in both the middle and upper cr ust was coeval and related to the development of transpressional and transt ensional structures along dextral strike-slip shear zones. Furthermore the development of foliated or unfoliated fabrics is related to competition bet ween rates of deformation and magmatic processes, which is a function of th e thermal state of the host rocks.