Thermochronology of hydrothermal alteration zones in the Kii Peninsula, southwest Japan: an attempt for detecting the thermal anomalies and implications to the regional exhumation history

Sueoka, Shigeru; Iwano, Hideki; Danhara, Tohru; Niwa, Masakazu; Kanno, Mizuho; Kohn, Barry P.; Kawamura, Makoto; Yokoyama, Tatsunori; Kagami, Saya; Ogita, Yasuhiro; Hirata, Takafumi

doi:10.1186/s40623-023-01921-5

Earth, Planets and Space

Table 6 Summary of zircon (U–Th)/He data

From: Thermochronology of hydrothermal alteration zones in the Kii Peninsula, southwest Japan: an attempt for detecting the thermal anomalies and implications to the regional exhumation history

Sample code	Grain ID	Mass [μm]	²³⁸U [ppm]	²³²Th [ppm]	Th/U	⁴He [ncc/mg]	F_T	eU [ppm]	(U-Th)/He age ± 1σ [Ma]
Sample code	Grain ID	Mass [μm]	²³⁸U [ppm]	²³²Th [ppm]	Th/U	⁴He [ncc/mg]	F_T	eU [ppm]	Raw	Corr
Unknown									Weighted mean age ± 1σ:	16.8 ± 3.9
HJG1-0 m	008	2.8	–	–	–	1665.3	–	–	–	–*
HJG1-0 m	015	1.3	302.0	162.7	0.54	477.4	0.60	340.3	11.5	19.3 ± 2.2
HJG1-1 m	010	2.8	481.2	242.7	0.50	827.8	0.71	538.2	12.6	17.8 ± 2.0
HJG1-1 m	003	2.4	584.4	294.2	0.50	489.0	0.71	653.5	6.2	8.7 ± 1.0
HJG1-3 m	008	2.2	256.8	129.0	0.50	374.1	0.69	287.1	10.7	15.5 ± 1.7
HJG1-3 m	004	3.7	570.2	212.8	0.37	910.8	0.75	620.2	12.1	16.2 ± 1.8
HJG1-10 m	009	3.1	901.1	292.4	0.32	1539.6	0.74	969.8	13.0	17.7 ± 2.0
HJG1-10 m	013	4.0	605.4	147.6	0.24	585.9	0.73	640.1	7.5	10.3 ± 1.2
HJG1-20 m	006	4.9	312.7	181.5	0.58	652.0	0.75	355.4	15.1	20.2 ± 2.3
HJG1-20 m	010	6.2	163.7	68.9	0.42	901.2	0.77	179.8	41.1	53.4 ± 6.0**
HJG2-0 m	002	4.6	147.2	128.0	0.87	210.9	0.76	177.3	9.8	12.8 ± 1.4
HJG2-0 m	004	5.7	171.6	110.2	0.64	438.1	0.77	197.5	18.2	23.6 ± 2.6
HJG2-1 m	006	1.9	573.4	372.7	0.65	956.0	0.68	660.9	11.9	17.4 ± 1.9
HJG2-1 m	009	1.7	483.1	481.1	1.00	864.2	0.64	596.2	11.9	18.5 ± 2.1
HJG2-3 m	003	5.3	659.8	179.8	0.27	1295.3	0.76	702.0	15.2	20.0 ± 2.2
HJG2-3 m	010	2.2	274.5	133.2	0.49	415.8	0.70	305.8	11.2	15.9 ± 1.8
HJG2-10 m	006	3.7	5122.1	12,243.4	2.39	635.9	0.73	7999.3	0.7	0.9 ± 0.1**
HJG2-10 m	009	3.8	309.1	176.4	0.57	554.9	0.72	350.5	13.0	18.1 ± 2.0
Fish Canyon Tuff: 28.3 ± 0.4 Ma (ZHe age ± 1σ; Gleadow et al. 2015)									Weighted mean age ± 1σ:	27.7 ± 3.1
FCT3	013	5.1	217.9	93.5	0.43	978.0	0.76	239.9	19.7	24.5
	103	9.8	356.9	213.0	0.60	1106.5	0.80	406.9	22.3	27.8
	108	4.5	342.0	182.1	0.53	1066.0	0.74	384.8	22.7	30.7

^aF_T is the α-ejection correlation (Farley et al. 1996; Hourigan et al. 2005). Proxy for alpha-radiation activity is computed as eU = [U] + 0.235[Th] (Shuster et al. 2006). [*sample lost during U–Th measurement; **not included in weighted mean calculations; Corr., corrected; eU, effective uranium concentration]

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