Archeointensity study on baked clay samples taken from the reconstructed ancient kiln: implication for validity of the Tsunakawa-Shaw paleointensity method

Earth, Planets and Space

Table 1 Results of the rock magnetic experiments and the Tsunakawa-Shaw paleointensity experiments

Sample	ARM0 ₀	N _hys	B _rc /B _c	M _rs /M _s	LTD	Anisotropy	First heating					Second heating					F	ΔAIC
	[10 ^-5 Am ² /kg]				[%]	ratio	H _c	Slope _A1	Slope _N	f _N	r _N	H _c	Slope _A2	Slope _T	f _T	r _T	(μT)
Floor surface
1	247	2	1.564	0.4267	21.8	1.12	40-180	0.882	1.28	(0.166)	(0.982)	0-180	1.03	(1.05)	0.999	1.00		−1.66
2	343	2	2.730	0.2696	9.1	0.972	40-110	0.932	1.08	0.369	1.00	0-180	1.02	0.978	0.986	0.999	43.2	0.17
5	302	2	1.470	0.4252	24.7	1.05	20-180	0.976	1.16	0.570	0.999	0-180	1.00	1.05	1.01	1.00	46.4	5.26
8	274	4	1.581	0.3970	16.5	1.03	20-180	0.991	1.20	0.530	0.999	14-180	1.03	1.05	0.779	0.999	48.0	−0.17
9	171	2	1.702	0.4296	32.9	1.06	20-180	0.939	1.21	0.691	0.999	0-180	1.04	0.984	0.998	1.00	48.4	11.6
11	261	4	2.029	0.3420	14.0	0.980	20-180	0.972	1.24	0.672	0.998	0-180	0.969	1.04	1.01	0.999	49.6	16.3
12	142	4	1.683	0.4074	24.2	1.24	20-180	1.04	1.20	0.503	0.999	0-180	1.01	1.02	0.999	1.00	48.0	0.18
13	262	4	1.750	0.4001	28.5	1.10	45-180	0.925	0.994	(0.233)	0.998	0-180	1.00	1.05	0.993	1.00		11.9
	250	8	1.814	0.3872	21.4												47.3
	±66		±0.406	±0.0552	±7.9												±2.2
−20-cm level
15	38.2	2	2.153	0.3064	7.8	1.06	70-180	0.826	1.46	(0.206)	0.995	0-180	1.08	0.984	1.01	1.00		0.55
16	21.0	2	2.385	0.2372	4.0	0.986	20-120	1.01	0.790	0.743	0.996	0-180	1.08	0.999	0.977	0.998	31.6	−0.31
18	3.69	2	3.639	0.1344	20.5	0.941	20-180	1.03	0.909	0.623	(0.964)	0-180	0.939	1.01	0.914	0.968		−0.92
19	5.35	2	4.905	0.1164	7.5	0.958	20-180	1.00	0.863	0.547	(0.883)	0-180	0.934	0.985	0.970	0.986		7.79
	17.1	4	3.271	0.1986	10.0												31.6
	±16.1		±1.270	±0.0894	±7.2

ARM0₀, initial ARM0 intensity after LTD; N_hys, number of chips for the hysteresis measurements; B_rc/B_c, M_rs/M_s, sample-averaged ratios of coercivity of remanence (B_rc) to coercive force (B_c) and saturation remanent magnetization (M_rs) to saturation magnetization (M_s); LTD, LT demagnetized fraction of ARM0; anisotropy ratio, ratios of ARM_{TRM direction} to ARM_{NRM direction} before laboratory heating; H_c, the coercivity interval taken for the linear segments; slope_A1, slope_A2, slopes of ARM spectra for H_c in the ARM0-ARM1 and ARM1-ARM2 diagrams; slope_N, slope_T, slopes of the linear segments in the NRM-TRM1* and TRM1-TRM2* diagrams; f_N, f_T, NRM and TRM1 fractions of the linear NRM-TRM1* and TRM1-TRM2* segments; r_N, r_T, correlation coefficients of the linear NRM-TRM1* and TRM1-TRM2* segments; F, calculated paleointensity; ΔAIC, AIC difference between linear and quadratic fit (Yamamoto and Tsunakawa, 2005); Numbers in parentheses indicate out of the selection criteria; Numbers in italic are averaged values with their 1 σ for the sample groups.