886-857 Ma granites from Yenisey Ridge formed long before their collision with the western margin of the Siberian Craton

Abstract:

Yenisei Ridge represents the key geological structure in the western framing of the Siberian Craton, playing a significant role in regional and global geodynamic paleoreconstructions. This Late Precambrian orogenic belt stretches along the Yenisei River and is built of terranes of different nature (Vernikovsky et al., 2003). The largest structure of the Yenisei Ridge is the Central Angara terrane enclosing 886-857 Ma Yeruda granites. Origin and age of Yeruda granites along with paleogeographic position of the Central Angara terrane at the time of their formation were investigated using combined petrological, geochemical, geochronological and paleomagnetic approach. Yeruda granites were emplaced 886-857 Ma and are characterized by fractionated compositions, transitional between I- and S-types. The final stage of 859-857 Ma marks the formation of leucocratic granites, including high-K adakites or continental type (C-type), which could be formed during post-orogenic phase following extreme crustal thickening as described in (Xiao, Clemens, 2007). The calculated apparent movement of polar wonder (APWP) for Yeruda granites is significantly different from the trajectory of Siberia during Early Neoproterozoic, corresponding to paleolatitude difference of more than 8.6°. This clearly indicates that the Central Angara terrane was thousands of kilometers away from Siberia at the time of Yeruda granites emplacement.