Stalagmite evidence for East Asian winter monsoon variability and 18O-depleted surface water in the Japan Sea during the last glacial period

Progress in Earth and Planetary Science

Table 1 Uranium and thorium isotopic compositions and ²³⁰Th ages (before 1950 AD) for subsamples of stalagmite FG02 by MC-ICP-MS

Horizon (mm)	Weight (g)	²³⁸U (ppb)		²³²Th (ppt)		δ²³⁴U (measured)^a		[²³⁰Th/²³⁸U] (activity)^c		[²³⁰Th/²³²Th] (ppm)^d		Age (uncorrected)		Age (corrected)^c,e		δ²³⁴U_initial (corrected)^b
9.5	0.2257	6.01	± 0.00	3818	± 13.4	387.7	± 2.4	0.2987	± 0.0129	7.8	± 0.3	26165	± 1265	13537	± 6838	402.8	± 8.0
29.0	0.2416	9.33	± 0.01	1247	± 4.2	423.9	± 2.2	0.2957	± 0.0056	36.5	± 0.7	25126	± 530	22665	± 1349	452.0	± 2.9
61.0	0.2635	8.21	± 0.01	543	± 2.9	407.2	± 3.1	0.2889	± 0.0039	72.1	± 1.0	24810	± 377	23585	± 720	435.2	± 3.4
80.7	0.2880	7.78	± 0.02	446	± 2.6	436.7	± 3.9	0.2778	± 0.0030	80.0	± 1.0	23213	± 283	22173	± 593	465.0	± 4.2
93.2	0.2944	6.32	± 0.03	293	± 2.4	443.8	± 7.1	0.2948	± 0.0027	105.1	± 1.2	24642	± 282	23809	± 501	474.7	± 7.6
120.7	0.3347	6.08	± 0.03	754	± 4.2	430.8	± 8.1	0.2993	± 0.0053	39.8	± 0.7	25323	± 524	23053	± 1255	459.8	± 8.8
148.5	0.2848	6.07	± 0.03	431	± 2.8	483.1	± 8.9	0.3159	± 0.0048	73.4	± 1.2	25812	± 472	24567	± 779	517.8	± 9.6
159.5	0.2749	6.32	± 0.04	233	± 2.6	494.0	± 11.4	0.3349	± 0.0032	149.9	± 2.0	27329	± 381	26691	± 492	532.8	± 12.4
178.7	0.2364	5.80	± 0.04	669	± 4.1	484.4	± 10.9	0.3733	± 0.0064	53.5	± 0.9	31127	± 660	29111	± 1202	525.9	± 12.0

^a234U = ([234 U/238 U] activity−1) × 1000.
^b234U_initial corrected was calculated based on 230Th age (T), i.e., 234U_initial = 234U_measured × e 234*T, and T is corrected age
^c[230Th/238 U]activity = 1 − e−230 T + (234U_measured/1000)[230/(230–234)](1 − e − (230–234) T), where T is the age. Decay constants are 9.1577 × 10⁻⁶ year-1 for 230Th, 2.8263 × 10^–6 year-1 for 234 U (Cheng et al. 2013), and 1.55125 × 10^–10 year-1 for 238 U (Jaffey et al. 1971)
^dThe degree of detrital 230Th contamination is indicated by the [230Th/232Th] atomic ratio instead of the activity ratio
^eAge corrections were calculated using an estimated atomic 230Th/232Th ratio of 4 ± 2 ppm