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Multi‐Wavelength Synchrotron Radiation XRF Determination of U and Th in Sedimentary Cores from Lake Baikal
Author(s) -
Phedorin Michael A.,
Goldberg Evgeny L.,
Bobrov Vladislav A.,
Khlystov Oleg M.,
Grachev Michael A.
Publication year - 2000
Publication title -
geostandards newsletter
Language(s) - English
Resource type - Journals
eISSN - 1751-908X
pISSN - 0150-5505
DOI - 10.1111/j.1751-908x.2000.tb00773.x
Subject(s) - geology , synchrotron radiation , uranium , x ray fluorescence , sedimentary rock , thorium , sediment , mineralogy , monochromatic color , paleontology , fluorescence , materials science , physics , optics , metallurgy
A new technique for the determination of uranium and thorium in lacustrine sediments is based on non‐destructive synchrotron radiation X‐ray fluorescence analysis (SR‐XRF) of sediment samples using monochromatic beams of different energies as excitation sources, with the recording and subsequent iterative processing of the X‐ray fluorescence spectra. The technique has a multielement capability and enables fast, simultaneous analysis of a few tens of elements. The proposed SR‐XRF technique was tested against INAA and ICP‐MS methods and showed a number of advantages with a generally good correlation of results by the three methods. Uranium and Th profiles have been measured at a time resolution of 2 kyr in a drill core (BDP‐96) from Lake Baikal bottom sediments deposited between 780 and 40 kyr B P. During this time span, peaks in the U and U/Th concentration marked warm climates. Oscillations of U and U/Th in Baikal bottom sediments during the Brunhes chron reflect climate‐induced global change in the volume of polar ice, controlled by long‐term cyclicity of the Earths orbital parameters. The response of these warm periods is similar to that observed earlier in shorter cores that span the two last interglacials (220‐0 kyr BP).