Multiwave XRF-SR determination of U and Th in bottom sediments of Lake Baikal: Brunhes paleoclimatic chronology

The paper presents a new method of U and Th determination in bottom sedimen ts implying synchrotron radiation with monochromatic beams at different ene rgies, registration, and iterative Joint processing of the resultant XRF (X -ray fluorescent) spectra series, The validity of the new method was proved by comparison of U and Th determinations by XRF-SR in different sediment s amples with earlier INAA and ICP-MS results for the same samples. Profiles of U and Th were measured at the sampling rate of 2 ka in a drilling core ( BDP-96-2) of bottom sediments from Lake Baikal deposited 40 to 780 ka BP. O scillations of U contents and U/Th ratios record global climate change thro ughout the Brunhes epoch (780 ka BP), and the response of these "warm" prox ies is similar to that observed earlier in shorter cores spanning the last two interglacials (220-0 ka BP).