Structural-metamorphic evolution of the Southern Yenisey Range of Eastern Siberia: implications for the emplacement of the Kanskiy granulite Complex

The Southern Yenisey Range of Eastern Siberia consists of the granulite fac ies Kanskiy Complex bordered in the west by the lower-grade Yeniseyskiy and Yukseevskiy Complexes. Three deformational events were recognized in each of the three complexes along the Yenisey River cross-section: a D1 fabric f orming event, a D2 shear and folding event, and a D3 shear event. Thrust ki nematics across the Southern Yenisey Range suggest that during the D2 event the Kanskiy Complex was thrusted along a regional ductile shear zone onto the lower-grade complexes. This resulted in shearing and folding as well as the development of a dynamic metamorphic zonation. In the low-grade greens tone belt part of the cross section (Yukseevskiy complex) D2 shearing is as sociated with peak prograde (T similar to 660 degrees C and P similar to 5. 8 kbar) metamorphism. The retrograde P-T path of the Yukseevskiy Complex co incides with minimum Tof the near-isobaric cooling P-T paths for the adjace nt granulites of the Kanskiy Complex (Perchuk et al., 1989). The metamorphi sm can therefore be attributed to deformation and heat transfer caused by e xhumation of the Kanskiy Complex in the time period 2000-1800 Ma which also defines the most significant tectono-thermal event in the Southern Yenisey Range. The tectono-metamorphic pattern and evolution of the low- to high-g rade metamorphic complexes of the Southern Yenisey Range is very similar to that described for the similar to 2600 Ma Limpopo Complex of Southern Afri ca and the similar to 1900 Ma Lapland Complex of the Kola Peninsula. Simila r geodynamic processes were therefore possibly responsible for the formatio n of these high-grade terrains suggesting that their formation is linked to a general geodynamic model.