Water content in arc basaltic magma in the Northeast Japan and Izu arcs: an estimate from Ca/Na partitioning between plagioclase and melt

Earth, Planets and Space

Table 1 Experimental conditions and results

Run#	Capsule#	Run durations (h)	T (°C)	Pressure (MPa)	Bulk H₂O (wt.%)^a	H₂O in melt (wt.%)^b	H₂O in melt (wt.%)^c	Phase and modal proportions (wt.%)^d	Calculated fO₂(ΔNNO)^e	Relative Fe-loss (wt.%)^f	K _D ^pl-melt _Ca-Na	An in plagioclase
HG442	C1838	12	1,150	100	0.77 (3)	0.91 (10)		Melt (85), pl (15)		−13	1.05 (17)	80.4
HG442	C1837	12	1,150	100	2.07 (9)	2.11 (13)	2.01 (19)	Melt (98), pl (2)		−6	2.21 (27)	88.4
G463	C1831	24	1,100	100	2.99 (12)	3.23 (17)	3.00 (25)	Melt (93), pl (5), mt (2)		0	3.14 (31)	91.3
G459	C1824	12	1,150	150	0.77 (3)	0.91 (10)		Melt (85), pl (15)		−11	0.93 (10)	76.9
G459	C1820	12	1,150	150	1.57 (11)	1.71 (16)	1.52 (14)	Melt (92), pl (8)		−8	1.56 (19)	84.7
G458	C1817	24	1,100	150	2.59 (9)	2.92 (10)		Melt (88), pl (10), mt (2)		−3	2.36 (33)	88.8
HG448	C1857	24	1,075	150	2.99 (12)	3.44 (13)		Melt (87), pl (10), mt (3)		1	2.78 (26)	90.2
G465	C1839	24	1,100	200	0.77 (3)	1.24 (11)		Melt (62), pl (32), ol (3), cpx (1), opx (2)	0.8	−14	1.06 (23)	79.4
G465	C1840	24	1,100	200	2.07 (9)	2.42 (10)		Melt (86), pl (12), mt (3)		5	2.11 (28)	87.7
G465	C1841	24	1,100	200	2.99 (12)	3.16 (13)	3.16 (27)	Melt (95), pl (3), mt (2)		6	2.42 (26)	89.9

^aH₂O content of starting materials analyzed by transmittance measurements using Fourier transform infrared spectroscopy (FTIR). Standard deviation is indicated in parentheses; ^bH₂O in melt calculated from mass balance. Standard deviation is indicated by parentheses; ^cH₂O in melt analyzed by Δreflectance measurements using FTIR. Standard deviation is indicated in parentheses; ^dphase proportion in weight percent indicated by parentheses. Abbreviation of phases: pl, plagioclase; mt, magnetite; ^efO₂ was calculated using the oxygen fugacity barometer (Sugawara 2001); ^fRelative Fe loss was calculated as (FeO_after − FeO_{starting material})/FeO_{starting material} × 100. FeO_after is the summation of FeO (total Fe as FeO) from all phase in run products.