Volcanogenic CO₂ Degassing in the Songliao Continental Rift System, NE China

Table 1

Chemical and C-He isotopic compositions of the spring gases in the WMVF.

Sample no.	T	N2	O2	Ar	CO2	CH4	He	He/Ar	N2/Ar	^4He/^20Ne				δ^13C (‰)	CO2/^3He (×10^9)
	(°C)	(%)	(%)	(%)	(%)	(%)	(ppm)
NYQ17	9.2	8.0	0.35	0.16	91.1	0.07	129	0.08	50	182	2.64	713	2.64	−7.2	1.9
NYQ18	7.7	8.7	0.55	0.18	90.5	0.14	278	0.15	49	153	3.10	597	3.10	−5.6	0.8
BYQ17	7.8	3.4	0.32	0.06	95.8	0.10	379	0.64	58	685	2.26	2675	2.26	−7.3	0.8
BYQ18	6.5	3.2	0.25	0.07	96.5	0.38	18	0.03	46	40	3.16	155	3.17	−6.0	12.1
HLQ17	19.8	4.6	0.88	0.08	94.1	0.02	10	0.01	58	38	2.34	150	2.35	−5.0	29.5
HLQ18	24.0	4.9	1.29	0.09	93.7	0.04	433	0.48	54	72	2.97	281	2.98	−2.6	0.5
FHQ17	12.7	15.8	3.66	0.25	80.2	0.08	718	0.28	62	145	2.81	568	2.81	−4.3	0.3
FHQ18	16.0	22.6	0.21	0.43	76.7	0.89	1845	0.43	53	359	3.18	1401	3.18	−2.5	0.1

(1) is the observed ³He/⁴He ratio divided by the ³He/⁴He ratio in the air (, [42]). (2) , where β represents the Bunsen coefficients assuming a groundwater recharge temperature of 10°C (β_Ne/β_He = 1.25, [43]), (⁴He/²⁰Ne)_M is the measured ratio of samples, and (⁴He/²⁰Ne)_Air is the ratio of the air (0.32, [42]). (3) is the air-corrected Helium isotope ratio by applying the following formula [44]: .