Occurrence of 1 ka-old corals on an uplifted reef terrace in west Luzon, Philippines: Implications for a prehistoric extreme wave event in the South China Sea region

Geoscience Letters

Official Journal of the Asia Oceania Geosciences Society (AOGS)

Table 1 U-Th isotopic compositions and ²³⁰Th ages for corals of Badoc Island by MC-ICPMS, Thermo Electron Neptune, at HISPEC, NTU

Sample ID	Weight g	²³⁸U ppb^a	²³²Th ppt	d²³⁴U measured^a	[²³⁰Th/²³⁸U] activity^c	²³⁰Th/²³²Th atomic (×10⁻⁶)	Age (year ago) uncorrected	Age (year ago) corrected^c,d	Age (year BP) relative to 1950 AD	δ²³⁴U_initial corrected^b
BAD-071914-2.1	0.26321	2324.0 ± 3.6	30.3 ± 1.8	145.2 ± 2.2	0.07067 ± 0.00017	89,269 ± 5199	6937 ± 22	6936 ± 22	6871.7 ± 22	148.1 ± 2.2
BAD-071914-2.2	0.20931	3151.7 ± 4.7	595.6 ± 2.6	147.2 ± 2.1	0.010623 ± 0.000038	926.8 ± 5.0	1014.3 ± 4.1	1009.9 ± 4.6	945.1 ± 4.6	147.6 ± 2.1
BAD-071914-2.3	0.21320	3130.4 ± 5.1	161.0 ± 2.2	143.4 ± 2.3	0.010119 ± 0.000035	3245 ± 46	969.2 ± 3.9	968.0 ± 3.9	903.1 ± 3.9	143.8 ± 2.3
BAD-022215-09	0.10863	2564.8 ± 2.4	27.5 ± 4.3	144.8 ± 1.4	0.0145 ± 0.0001	22293 ± 3471	1387 ± 5	1386.6 ± 5.4	1320 ± 5	145.4 ± 1.4
BAD-111815-01	0.14431	3374.9 ± 2.9	69.6 ± 3.2	145.4 ± 1.3	0.02898 ± 0.00013	23170 ± 1079	2793 ± 13	2793 ± 13	2727 ± 13	146.6 ± 1.4

Decay constants are 9.1705 × 10⁻⁶ year⁻¹ for ²³⁰Th, 2.8221 × 10⁻⁶ year⁻¹ for ²³⁴U (Cheng et al. 2013), and 1.55125 × 10⁻¹⁰ year⁻¹ for ²³⁸U (Jaffey et al. 1971)
^a[²³⁸U] = [²³⁵U] × 137.77 (±0.11‰) (Hiess et al. 2012); δ²³⁴U = ([²³⁴U/²³⁸U]_activity − 1) × 1000
^bδ²³⁴U_initial corrected was calculated based on ²³⁰Th age (T), i.e., δ²³⁴U_initial = δ²³⁴U_measured X e^λ234*T, and T is corrected age
^c[²³⁰Th/²³⁸U]_activity = 1 − e^−λ230T + (δ²³⁴U_measured/1000)[λ₂₃₀/(λ₂₃₀ − λ₂₃₄)](1 − e^{−(λ230 − λ234) T}), where T is the age
^dAge corrections, relative to chemistry date, were calculated using an estimated atomic ²³⁰Th/²³²Th ratio of 4 (±2) × 10⁻⁶ (Shen et al. 2008)