Table 2.

Helium isotope ratios (³He/⁴He), neon/helium ratio (²⁰Ne/⁴He), argon isotope ratio (⁴⁰Ar/³⁶Ar) and concentrations of argon, krypton and xenon in surface sediments of submarine mud volcanoes off Tanegashima Island obtained in this study.

Sample	Depth	Pore water	(3He/4He )obs	20Ne/4He	40Ar/36Ar	Ar	Kr	Xe
	cmbsf	g	RA		× 102	× 10–4 cm3STP/g	× 10–8 cm3STP/g	× 10–9 cm3STP/g
MV1	300	0.89 ± 0.05	0.23 ± 0.05	0.230 ± 0.120	3.22 ± 0.05	0.96 ± 0.01	1.49 ± 0.03	2.02 ± 0.05
MV2	18	2.29 ± 0.03	0.63 ± 0.01	0.271 ± 0.027	N.A	N.A	N.A	N.A
MV3-1	8	2.27 ± 0.03	0.34 ± 0.01	0.054 ± 0.005	N.A	N.A	N.A	N.A
MV3-2	13	2.64 ± 0.03	0.42 ± 0.01	0.276 ± 0.028	N.A	N.A	N.A	N.A
MV3-3	18	3.17 ± 0.03	0.74 ± 0.02	1.24 ± 0.12	N.A	N.A	N.A	N.A
MV14	274	15.48 ± 0.05	0.95 ± 0.01	0.835 ± 0.002	3.04 ± 0.01	1.050 ± 0.001	2.62 ± 0.01	4.72 ± 0.06
ASW	–	–	1	4.0	2.96a	3.61b	8.84c	13.56d

Data for seawater in equilibrium with the atmosphere are also shown.

N.A. : Not analyzed.

^aOzima and Podosek³⁷.

^bWeiss⁴⁰.

^cWeiss and Kyser⁴¹.

^dJenkins et al.⁴².