(Table 2) U and Th isotopic compositions of authigenic carbonates, bottom- and pore water and 230Th/234U ages of authigenic carbonates@en

Notes: All given statistical errors are two standard deviations of the mean (2Sigma). The used decay constants are: Lamda234U = 2.8262 x 10**-6 a**-1 (Cheng et al., 2000b); Lamda238U = 1.55125 x 10**-10 a**-1 (Jaffey et al., 1971); Lamda230Th = 9.158 x 10**-6 a**-1 (Cheng et al., 2000b). Corrections for U and Th chemistry blanks are negligible. Column 2: Subsamples of one carbonate sample are represented by numbers following letters. Samples labeled 'a' and 'b' are different aliquots of the same sample before dissolution. Column 11: The measured 234U/238U activity ratios (delta234U(0)) are presented as deviation permil from the equilibrium value, delta234U(0) = {(234U/238U) x (lamda234/lamda238) - 1} x 1000 (Edwards et al., 1987). Column 13: The decay-corrected 234U/238U activity ratios (delta234U(T)) are calculated from the Th corrected ages (column 10) delta234U(T) = delta234U(0) x e**(lamda234*t) (Edwards et al., 1987). Column 17: Maximum ages are calculated using the equation: (230Th/238U) = 1 - e**(lamda230*t) + [delta234U(0)] - 0.001 x [lamda230/(230Th - lamda234)] x [1 - e((lamda234 - lamda230)*t)]. Column 19: Best age estimate corrected for the effect of detrital Th. The uncertainty on the age correction is deduced from an uncertainty of +-50% on the 230Th/232Th activity ratio of 1.92.