Evidence of neoproterosoic continental subduction in the Baikal-Muya fold belt

The results of isotope-geochemical studies of eclogits and host rocks of the North-Muya block are presented. The studies showed broad variations both in the character of distribution of incompatible elements and in the Nd and Sr isotope composition of eclogits from the North-Muya block. The Nd isotope composition of eclogits is characterized by broad variations, which is reflected in the value of ɛ Nd ( T ), which has both positive (from +0.3 to +6.9) and negative values (from −0.5 to −16.8). The isotope characteristics for the both samples of eclogits (Mu 12-11, 12-12) with the lowest values of ɛ Nd ( T ) clearly indicate protolith contamination by an ancient source of Meso- or Paleoarchean age. Consequently, the melts of the protoliths of the eclogites intruded into the continental crust, and the eclogite-gneiss complex of the North-Muya block may be considered as a paleozone of the continental subduction.