Title

N.I. GUSEV, L.Yu. SERGEEVA (VSEGEI), S.G. SKUBLOV (IGGD RAS, SPMU), N.G. BEREZHNAYA, A.N. LARIONOV (VSEGEI)

Composition and relationships of the Early and Late Archaean granulites in the Bekelekh Formation of Anabar Shield (Siberian Craton)

The Bekelekh Granulite Formation in the section along the river Bol. Kuonamka contains Early Archean mafic crystalline schists and trondhjemite plagiogneisses of the TTG series (zircon U­-Pb age of 3.41–3.30 Ga, whole rock T_Nd(DM) 3,43–3,33 Ga) in very small quantities. The predominant are Late Archean diorite – quartz­diorite two­pyroxene plagiogneisses (zircon U-­Pb age of 3.16–2.96 Ga, whole rock T_Nd(DM) 3,29–3,21 Ga) containing a subordinate amount of mafic and ultramafic rocks with a feature of stratified intrusions. Enderbitization is widespread as a formation of granitoids of the TTG series with an age of 2.87 Ga. Potassium alaskite granite gneisses have an age of 2.62 Ga. According to the Lu-­Hf systematic in anatectic zircon with the age of 3.05 Ga, the early stages of formation of the Anabar shield crust constrains by the age of T_Hf(DM) 3.6–3.5 Ga and T^C_Hf 3.9–3.8 Ga. Zircon with an age of 2.87 Ga is characterized by T_Hf (DM) 3.22–3.15 Ga and T^C_Hf 3.43–3.33 Ga.
Keywords: Anabar shield, Daldyn Group, Bekelekh Formation, Early Archean, Late Archean, granulites, enderbitization, zircon, U-­Pb age SHRIMP II, Sm-­Nd, Lu-­Hf systematics.