Home – Home – Jornals – Russian Geology and Geophysics 2004 number 3

The Uralian orogen includes a group of continental terranes in the west and island-arc terranes in the east. The East Uralian zone consists of two large island-arc terranes of different ages: the Tagil terrane in the northern and central Urals and the Magnitogorsk terrane in the southern Urals. The two terranes produce a strong gravity anomaly in their western part known as the Main Uralian Gravity Supermaximum. The axis of the anomaly is delineated by mafic-ultramafic complexes of the Ural Platinum belt within the Tagil terrane but no such complexes are exposed within the Magnitogorsk terrane in the south. Two-dimensional Bouguer gravity inversion of the gravity step and the supermaximum along seven profiles traversing the Irendyk zone in the western Magnitogorsk terrane indicates that gabbro complexes similar to those in the Platinum belt may be buried at several kilometers beneath basaltic andesites of the Irendyk island arc. The inversion was based on the known geometry of the gravity producing bodies in the Platinum belt, and the results were interpreted taking into account gravity and geological evidence in view of tectonic similarity between the Tagil and Magnitogorsk terranes. The gabbro complexes in the Magnitogorsk terrane may have remained buried because of a lower-angle dip and a shallower base level of erosion of the Irendyk island arc.