Home – Home – Jornals – Russian Geology and Geophysics 2004 number 12

In the central Baikal-Vitim folded area, a rock complex has been revealed which was earlier considered to be part of the thick Vendian Padrokan Formation. The complex lies with erosion over the Lower-Middle Cambrian Yanguda Group. It is of volcanoterrigenous composition and Early Ordovician(?) age. The complex is recognized as the Kaalu Formation, which is more than 3200 m in visible depth. It formed in graben-like troughs. The trough periphery is made up mainly of proluvial-alluvial and olistostrome deposits, and the central parts, of alluvial- lacustrine sediments. Volcanogenic formations are abundant traces of tuffaceous matter in terrigenous sediments and less frequent tuffs, lavas, and crater facies. The volcanics are of contrasting rhyolite-basaltic composition. Similar formations in other zones of the central Baikal-Vitim folded area, which were earlier dated to the Late Cambrian, might be in fact of post-Middle Cambrian age.