Lake Baikal (Russia) contains a variety of turbidite systems in different tectonic and depositional settings that provide tests for the role of Quaternary climatic change on turbidite system growth. During Pleistocene glacial climates, all types of systems exhibit increased sediment supply (high sedimentation rates, high net sand percent, thick sand turbidites) and progradation. During Holocene interglacial climate, all systems exhibit reduced sediment supply and retreat. Seismic profiles from the large Selenga Fan and small Tompuda Fan show (1) maximum fan growth during the late Pleistocene glacial melt time, where lobes and large channels reached the distal outer fan, and (2) fan retreat during the transition to the fully developed Holocene interglacial climate. For example, the Selenga Fan surface lobes backstepped similar to 55 km from the distal outer fan to the distal inner fan, and the large outer fan surface channel (similar to 750 m wide, similar to 20 m levee relief) evolved to a smaller surface channel (similar to 450 m wide, similar to 13 m levee relief) that extended only to the end of the inner fan. These results show that Quaternary climate controls the growth of the Lake Baikal turbidite systems in a setting where there are no significant water-level changes, which often are cited as the main control on turbidite system growth. The Lake Baikal and other marine turbidite systems suggest that climatic control of sediment supply, unrelated to sea-level lowering and tectonic effects, may have been a much more important control for turbidite systems than previously believed, not only during the Pleistocene, but perhaps also for ancient systems. |
