Matuyama–Brunhes geomagnetic reversal record and associated key tephra layers in Boso Peninsula: extraction of primary magnetization of geomagnetic fields from mixed magnetic minerals of depositional, diagenesis, and weathering processes

Earth, Planets and Space

Table 1 Chemical analysis of a tephra layer (tephra B) from Terasaki section (this study), Byk-E from Yoro river (the Chiba section) and Byk-E from M44 section (Nanayama et al. 2016)

Target	Tephra	N	Method		Oxides (wt%)
Target	Loc	N	Method		SiO₂	TiO₂	Al₂O₃	FeO	MnO	MgO	CaO	Na₂O	K₂O	Total
Hornblende	Byk-E	20	a	Average	44.25	1.84	10.15	13.16	0.78	13.52	10.67	1.92	0.49	96.78
	Yoro River			Std. Dev	0.99	0.31	0.94	0.61	0.29	0.61	0.30	0.16	0.05	0.43
	Tephra B	5	a	Average	45.07	1.75	9.29	13.13	0.33	13.73	10.89	1.73	0.36	96.29
	Terasaki			Std. Dev	2.99	0.58	2.81	2.54	0.16	1.50	0.45	0.42	0.18	0.52
Volcanic glass	Byk-E	20	b	Average	66.76	0.21	12.97	1.14	0.13	0.26	1.74	3.51	2.92	89.63
	Yoro River			Std. Dev	0.79	0.07	0.59	0.12	0.06	0.05	0.31	0.20	0.20	0.84
	Byk-E	20	a	Average	67.00	0.21	12.79	1.23	0.16	0.31	1.67	3.49	2.93	89.79
	M44			Std. Dev	0.80	0.05	0.16	0.12	0.08	0.04	0.07	0.07	0.07	1.00
N: number of measured grains
Method	a	EDS: HORIBA EMAX Evolution EX-270, SEM: HITACHI SU1510, acceleration voltage of 15 kV and a beam current of 0.3nA
	b	EDS: HORIBA EMAX ENERGY EX-250, SEM: HITACHI S3000H, acceleration voltage of 15 kV and a beam current of 0.3nA