Variability in palaeoclimatic periodicity over 2,500 kyr from magnetic susceptibility of Lake Baikal sediments

Abstract

Magnetic susceptibility was measured on the sedimentary core, BDP-96-2 (100 m length), drilled at the Academician Ridge of Lake Baikal, central Siberia. The palaeomagnetic study has showed that the sediment core covers the past 2,500kyr. The magnetic susceptibility of BDP-96-2 showed high value during glacial periods and low value during interglacial periods, therefore, the susceptibility can be considered to be a good proxy for palaeoclimate around Lake Baikal region.

Spectral analysis to the susceptibility showed that principal periodicity well corresponded to the Earth's orbital cycles. Temporal changes in spectral power of principal periodicities showed a dominance of 100 kyr cycle since 1,200 kyr B.P. and an increase of 23 kyr cycle since 400 kyr B.P. The increase of 100 kyr cycle has been observed also in ODP records around 1200~700 kyr B.P. This variability in the periodicity is thought to be a reflection of change in the global climatic system related to the elevation of Himalayan Mountains. This study demonstrates that the signal of this global climatic change was also found in continental-interior region such as Lake Baikal. Whereas, the increase of 23 kyr precession cycle since 400 kyr B.P. is distinctive of Lake Baikal record. This suggests that local climatic system around Lake Baikal became highly sensitive to the solar insolation since 400 kyr B.P.