The Upper Age Boundary of the Formation of the Olondo Fragment of the Tokko–Khani Greenstone Belt, Aldan Shield: U–Pb (ID-TIMS) Geochronological Data

This work presents new U–Pb ID-TIMS geochronological data obtained for the rocks of the metagabbro–diorite–tonalite complex of the Olondo fragment of the Tokko–Khani greenstone belt of the Aldan Shield, Siberian Craton. Wide development of ultramafic and mafic volcanics associated with felsic volcanics has been recognized only within this fragment. It was established that the protoliths of metagabbro–diorite and quartz metadiorite intruding metavolcanic and metasedimentary rocks were crystallized at 3002 ± 5 and 3005 ± 7 Ma, respectively. The obtained age estimates determine the upper age boundary of the formation of the Olondo supracrustal rocks (3012–2997 Ma). The Nd model ages of the Olondo metaandesites and metadacites are close to 3.0 Ga, which, to the first approximation, determines the lower age boundary of their formation. Thus, the sedimentary–volcanogenic sequence of the Olondo fragment are about 3.0 Ga old, and their formation, including superimposed structural and metamorphic transformations, occurred within a short period (a few million years).