Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity

Earth, Planets and Space

Table 4 Summary of API determination using a bootstrap approach (in a similar way to that documented in Shaar et al. 2011) for the IZZI-Thellier results

Specimen	NRM0 (Am²/kg)	B_lab (μT)	θ	k	BDS_m	Information of specimen-level paleointensity estimates		Bootstrap constraints of overall mean^a
Specimen	NRM0 (Am²/kg)	B_lab (μT)	θ	k	BDS_m	B_min–B_max (μT)	B_max/B_min		95% confidence interval (µT)	Mean ± SD (µT)
B1A-1-2	7.92E–04	15.0	28	1.243	0.446	3.2–51.3	16	N = 8	9.9–24.0	16.6 ± 3.6
B1B-1-2	1.05E–03	15.0	34	1.167	0.467	3.1–39.9	13	N = 2 (B_max/B_min < 5)	6.6–19.7	12.6 ± 3.5
B1B-2-2	9.53E–04	15.0	54	1.191	0.467	3.1–39.4	13	N = 2 (B_max/B_min < 5)	6.6–19.7	12.6 ± 3.5
B1D-1-2	9.47E–04	15.0	99	1.123	0.333	4.0–41.8	10
B1E-1-2	8.49E–04	15.0	70	1.142	0.333	3.8–38.1	10
B1G-1-2	9.00E–04	15.0	50	1.163	0.346	3.3–39.9	12
B2C-1-2	8.02E–04	15.0	84	0.720	0.403	4.9–20.7	4.2
B2C-2-2	1.29E–03	15.0	43	0.993	0.403	5.6–25.1	4.5

NRM0, B_lab, θ, and k are the same as in Table 3. BDS_m, the associated mean value from the measurements of bulk domain stability (Paterson et al. 2017) by 4 subsamples for the drilled samples. B_min, B_max, the minimum and maximum of all of PI estimates that meet a loose set of selection criteria (n ≥ 4, f ≥ 0.3 and β ≤ 0.2; see Paterson et al. (2014) for definitions of the statistics) for each specimen
^aDescribes the information on an overall mean of API estimates obtained when running a re-sampling routine that randomly picks values from the B_min to B_max for each specimen and calculates a large number of their means (n = 10,000): N, the number of specimens used in the bootstrap procedure; S.D., the standard deviation of the 10,000 means. See “IZZI-Thellier (IZZI-T) determination” section for details