KENGEDE MAFIC DYKE SWARM AND EXPANSION OF THE 1.50 Ga KUONAMKA LARGE IGNEOUS PROVINCE OF NORTHERN SIBERIA

Abstract

Within the Anabar shield in the northern part of the Siberia, Late Precambrian mafic igneous units are widespread, which form dyke swarms of different ages of different trends. This paper presents new data on the composition, structure and U-Pb dating of the E-W trending Kengede dyke swarm. Three new U-Pb ID-TIMS baddeleyite ages (1496±7, 1494±3 and 1494±5 Ma) were obtained from three dykes, indicating that the Kengede swarm is part of the 1500 Ma Kuonamka large igneous province (LIP). The previously recognized Kuonamka Large Igneous Province (LIP) extends for 700 km from the Anabar shield to the Olenek uplift in the northern part of the Siberia and is potentially linked to coeval dykes and sills of the São Francisco craton and the Congo craton. The newly dated Kengede swarm is parallel to but offset by 50 km from the previously dated 1501±3 Ma Kuonamka swarm, and the identification of these two subparallel dyke subswarms of the Kuonamka LIP supports the earlier interpretation that mantle plume centre was located along the extrapolated trend of the dykes near the eastern or western margin of the Siberia. The paper examines features of sulfide Cu-Ni mineralization in dolerites of the Kengede and East Anabar dyke swarms and discusses potential Cu-Ni-sulfide mineralization linked to the Precambrian mafic dyke swarms of different ages in the north-east of the Siberia.