Early Proterozoic Age of the Tyrkandin Fault Zone, the Aldan Shield: U-Pb Dating of Fragments of Single Zircon Grains

摘要

In recent years, we have obtained numerous geo-chronological data that make it possible to constrain the timing of major mapable structures in the central Aldan Shield. Unfortunately, such data are still absent for the eastern part of this region. Therefore, it is difficult to elaborate integrated geodynamic models of the evolution of Precambrian complexes of the Siberian Craton basement. This paper is devoted to geochronological study of the Tyrkandin fault zone, which is one of the largest sutures in the eastern Aldan Shield (Fig. 1). This 20-km-wide zone extends more than 500 km. It is characterized by positive magnetic linear anomalies. In addition, the zone coincides with a large gravity step, which separates blocks with different structures of the earth's crust. It should also be noted that the Tyrkandin fault zone hosts numerous mafic and ultramafic bodies. In addition, unlike surrounding granulites, K- and K-Na-grani-toids, which are widespread in this zone, form migma-tite leucosome, pegmatoid granite veins, and concordant granite gneiss and gneissic granite bodies.