ABSTRACT

New high-resolution seismic reflection data off the NE shore of Lake Baikal indicate intimate relations between recurrent late Pleistocene glaciations onshore and lacustrine sedimentation processes offshore. The basin floors bordering the most extensively glaciated regions of the lake margin are characterized by large sublacustrine fans. Extending over 20 km in diameter, the Frolikha Fan is among the largest fans in northern Lake Baikal. Morphologically the fan consists of three parts: the upper fan, which is marked by a prominent single-leveed channel, the middle fan, consisting of smaller distributary channels (without levees) associated with convex fan lobes, and the lower fan, which is poorly developed and characterized by a transition of lobate sedimentary units into basin-plain or bottom-current channel deposits. The extremely steep morphology of the Frolikha Fan, internal seismic characteristics, and in particular the depositional geometry and seismic signature of the upper fan division indicate that the fan formed during glacial periods in a proglacial depositional environment. In fact, large moraines onshore Frolikha Bay document multiple Pleistocene glaciations down to and beyond the present-day shoreline into the lake basin. It is therefore very likely that the Frolikha Fan developed in response to the recurrent late Pleistocene advances of valley glaciers into Lake Baikal.