RUSSIA 463 Figure Sedimentary basins of the Siberian Craton (compiled by Nikishin and Fokin) In Quaternary times, the craton was glaciated many times, but thick glaciers formed only in its northern part and the rest of the area was affected by thick permafrost that survives until the present day Neoproterozoic Orogens Shatsky proposed the term Baikalides for the Neoproterozoic orogens on the flanks of the major cratons of Russia Their type locality is in the Patom Highlands in northern Transbaikalia, but they were also distinguished in the Yenisei ridge, northern Taimyr, and Timan Their slivers are recognized inside the Palaeozoic to Cenozoic orogens Until the 1980s, the interpretation of Baikalide age was mostly based on stratigraphic data Recently, the Neoproterozoic age of the type locality in northern Transbaikalia was questioned Some researchers suggested that the Baikalides are Early or Middle Proterozoic structures, whereas others proposed a Caledonian age However, the deformed sequences in the Patom Highlands are unconformably overlapped by less deformed Vendian to Cambrian sedimentary rocks, indicating Neoproterozoic deformations In addition, isotopic dating of syn- and postmetamorphic granitoids in the Yenisei ridge, Taimyr, and Timan also demonstrate the validity of Neoproterozoic deformations Patom Highlands This is an oroclinal embayment in the south of the Siberian Craton, extending from Lake Baikal towards the Patom Highlands (Figure 1) In the 1970–1980s, the Baikalides were interpreted as an Early Proterozoic orogen Subsequent regional mapping re-confirmed that the orogen is Neoproterozoic Most of this area is occupied by the Barguzin granitoid batholith In the 1960s, it was considered as Proterozoic In the 1970–1980s, the first K-Ar data showing its Early Palaeozoic age were obtained However, application of more advanced techniques