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

Hyeon-Seon Ahn; Yuhji Yamamoto

doi:10.1186/s40623-019-1107-6

Earth, Planets and Space

Table 2 Summary of results of the Tsunakawa–Shaw API experiments

From: 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

Specimen	NRM_LTD,0 (Am²/kg)	ARM0₀ (Am²/kg)	MDF_A0 (mT)	LTD_A00 (%)	NRM					First heating						Second heating						B_lab (μT)	B_anc (μT)
Specimen	NRM_LTD,0 (Am²/kg)	ARM0₀ (Am²/kg)	MDF_A0 (mT)	LTD_A00 (%)	H_L (mT)	H_H (mT)	D (°)	I (°)	MAD_free (°)	H_L (mT)	H_H (mT)	Slope_A0	Slope_N	f_N	r_N	H_L (mT)	H_H (mT)	Slope_A1	Slope_T	f_T	r_T	B_lab (μT)	B_anc (μT)
B1A-1-1	8.63E–04	1.17E–03	28	17	8	180	nd	nd	1.6	8	180	0.936	0.397	0.926	0.998	0	180	0.993	0.976	0.989	1.000	30.0	11.9
B1A-2-1	9.51E–04	1.11E–03	27	19	18	140	350.1	39.2	0.9	18	60	0.841	0.591	0.596	0.999	0	180	0.991	0.989	0.991	1.000	20.0	11.8
B1B-1-1	9.80E–04	1.41E–03	31	14	4	180	nd	nd	1.0	4	180	0.942	0.385	0.969	0.997	0	180	0.999	1.029	0.989	0.999	30.0	11.6
B1B-2-1	8.66E–04	1.27E–03	30	13	2	140	353.7	45.7	1.1	2	140	0.909	0.566	0.986	0.997	0	180	1.013	0.988	0.989	1.000	20.0	11.3
B1D-1-1	7.11E–04	8.90E–04	25	24	20	180	nd	nd	2.3	20	180	0.829	0.977	0.624	0.995	0	180	0.989	1.000	0.985	0.999	15.0	14.7
B1D-2-1	8.00E–04	8.93E–04	26	23	10	140	115.6	− 77.0	1.2	10	140	0.852	0.665	0.896	0.998	0	180	1.013	0.973	0.990	1.000	20.0	13.3
B1E-1-1	9.08E–04	9.52E–04	29	20	10	180	nd	nd	1.0	10	180	0.869	0.861	0.928	0.998	0	180	0.987	1.003	0.993	1.000	15.0	12.9
B1E-2-1	5.42E–04	8.72E–04	28	21	10	140	351.0	42.6	0.9	10	140	0.842	0.589	0.902	0.998	0	180	1.004	0.990	0.989	1.000	20.0	11.8
B1G-1-1	8.53E–04	1.04E–03	28	20	10	180	nd	nd	1.4	10	180	0.878	0.947	0.902	0.996	0	180	0.998	1.005	0.989	1.000	15.0	14.2
B1G-2-1	6.59E–04	1.03E–03	28	21	10	140	355.9	29.3	0.9	10	140	0.902	0.611	0.883	0.996	0	180	0.981	1.021	0.988	1.000	20.0	12.2
B2B-1-1	3.79E–04	1.60E–03	29	21	20	180	nd	nd	7.5	20	180	0.791	0.210	0.655	*0.985*	0	180	0.982	*1.136*	0.977	0.999	15.0	nd
B2B-2-1	5.96E–04	1.57E–03	23	20	22	140	nd	nd	8.2	22	140	0.724	0.179	0.599	*0.991*	0	180	1.000	*1.130*	0.974	0.999	20.0	nd
B2C-1-1	9.65E–04	1.63E–03	31	11	22	180	nd	nd	1.7	22	180	0.753	1.055	0.721	0.998	0	180	0.978	1.027	0.985	0.999	15.0	15.8
B2C-2-1	9.64E–04	9.64E–04	28	13	14	140	344.4	37.1	1.0	14	140	0.813	0.797	0.884	0.999	0	180	0.973	1.023	0.990	0.999	20.0	15.9
B2D-2-1	1.70E–04	1.38E–03	26	23	10	140	336.3	29.9	3.6	10	140	0.578	0.222	0.907	*0.979*	0	180	0.996	*1.091*	0.983	1.000	20.0	nd
B2E–1-1	3.79E–04	1.53E–03	25	23	16	180	nd	nd	6.1	16	180	0.562	0.239	0.669	*0.988*	0	180	0.994	*1.075*	0.970	0.999	15.0	nd
B2E–2-1	2.31E–04	1.38E–03	20	24	12	140	339.3	37.9	5.5	12	140	0.527	0.168	0.701	*0.978*	0	180	1.002	*1.069*	0.975	0.999	20.0	nd
B2F-1-1	3.11E–04	1.56E–03	23	16	14	180	nd	nd	6.2	14	180	0.560	0.219	0.644	0.995	2	180	1.016	1.038	0.978	0.999	15.0	3.29
B2F-2-1	2.87E–04	1.40E–03	19	22	20	140	344.8	39.9	5.1	20	140	0.525	0.179	0.587	*0.989*	0	180	0.993	1.041	0.980	0.999	20.0	nd
B2G-1-1	5.31E–04	1.44E–03	30	23	12	180	nd	nd	4.5	12	180	0.619	0.359	0.918	*0.976*	0	180	0.987	*1.131*	0.973	0.999	15.0	nd
B2G-2-1	4.36E–04	1.39E–03	24	23	20	140	351.1	41.3	5.9	20	140	0.623	0.203	0.602	0.996	0	180	0.984	*1.139*	0.983	1.000	20.0	nd
																				N	Mean ± SD (µT)
																		B1 site mean		10	12.6 ± 1.2
																		B2 site mean		3	11.7 ± 7.3
																		B2 site mean#		2	15.9 ± 0.1
																		Overall mean		13	12.4 ± 3.2
																		Overall mean#		12	13.1 ± 1.7

NRM_LTD,0, intensity after LTD for NRM. ARM0₀, intensity after LTD for ARM0. MDF_A0, median destructive field of ARM0 in progressive AFD. LTD_A00, LT demagnetized fraction of ARM0, expressed as (ARM0 intensity after LTD)/(ARM0 intensity before LTD) × 100. H_L, H_H, low (high) limit of the interval of AF steps chosen for the determination of a characteristic direction or a linear segment. D, I, MAD_free, declination and inclination in the geographic coordinate system and the maximum angular deviation determined by the PCA free-floating fit (Kirschvink 1980) for the chosen intervals of data. Time, hold time at the set peak temperature (610 °C) in each heating process. The slope_A0, slope_A1, and slope values determined from all data points after LTD in each of the ARM0-ARM1 and ARM1-ARM2 diagrams. The slope_N, slope_T, slope values of the chosen linear segment in each of the NRM-TRM1* and TRM1-TRM2* diagrams. The f_N, f_T, NRM, and TRM1 fractions of the chosen linear NRM-TRM1* and TRM1-TRM2* segments. The r_N, r_T, correlation coefficients for linearity of the chosen linear segment of NRM/TRM1* and TRM1/TRM2* data points, respectively. B_lab, laboratory DC field during the TRM1 and TRM2 acquisitions. B_anc, API estimate
“nd” denotes “not determined”. Arabic numerals with bold italic denote the values failing to meet the corresponding selection criterion. In the bottom of the table, site means and overall means of API estimates are listed
The mean value with # mark is calculated from all other specimen-level estimates excluding one for specimen B2F-1-1 (3.29 μT)

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