Table 1.

Table 1. Important gas hydrate measurements and comparisons to nearby sediment gas composition.

Sample type Hole, core,
section Depth (mbsf) Volume gas/
volume water Volume gas/
volume water
(chlorinity correction) Chlorinity
(mM) C₁
(%) C₂
(ppmv) C₃
(ppmv) i-C₄
(ppmv) n-C₄
(ppmv) CO₂
(%) C₁/C₂+C₃ ¹³C C₁(PDB) D C₁(SMOW) ¹³C CO₂(PDB) D H₂O
(SMOW)

Gas tube
994A-30X-5
246.8

83.6
64
32.2
13.8
4.6
16.4
8670
-68.1

-5.3

Gas tube
994A-31X-5
257.3

93.9
86
2.0

2.8
10670

Free gas
994C-31X-3
255.1

92.0
125
0.0
14.3
3.3
8.0
7330

Hydrate gas
994C-31X-7
260.0
154
173
57
98.8
86
2.0
0.0
0.0
1.2
11230
-67.0

-5.7

Hydrate gas
996A-1H-1
0.1

99.3
1010
12.0
1.2
0.7
0.4
970

Free gas
996A-8H-3
50.3

99.3
629
28.2
11.1
2.5
0.8
1510

Hydrate gas
996A-8H-4
52.5

99.8
772
0.5
0.0
0.0
0.1
1290
-69.3

-23.2

Free gas
996A-8H-5
52.8

99.8
697
19.5
4.5
1.0
0.2
1390

Hydrate gas
996A-9H-CC
63.8

99.9
754
6.8
1.7
0.7
0.0
1310
-67.4

-19.9

Hydrate gas
996B-1H-1
2.1
43
58
169
99.3
969
11.9
2.5
0.6
0.6
1010

-199.7

13.8

Hydrate gas
996B-1H-1
2.1
18
29
248
99.4
753
8.9
1.7
0.4
0.5
1310

10.4

Hydrate gas
996C-1H-1
2.3
45
78
294
99.3
719
7.3
1.6
0.5
0.4
1370

9.2

Hydrate gas
996C-1H-1
2.3
58
90
245

10.3

Hydrate gas
996-C-2H-CC
2.4
24
48
352
99.8
857
15.8
4.3
0.9
0.0
1140
-65.9

-26.9
8.1

Free gas
996D-4H-5
26.9

98.5
720
6.5
1.8
0.6
1.5
1360

Hydrate gas
996D-5X-CC
32.1
59
107
317
99.7
747
18.3
3.2
0.8
0.3
1300

12.9

Free gas
996D-6H-4
45.0

98.9
776
22.3
5.6
1.9
1.0
1240

Hydrate gas
996D-6H-5
45.9

99.6
744
10.9
2.4
0.6
0.3
1320
-66.6
-175.0
-22.3

Free gas
996E-7X-5
48.5

98.1
637
20.4
6.2
1.6
1.9
1490

Hydrate gas
996E-7H-CC
58.6
142
145
21
99.7
719
6.9
1.6
0.4
0.2
1370
-70.7
-193.1
-21.9
17.1

Free gas
997A-41X-3
321.8

76.4
138
15.8
18.4
6.4
23.5
4980
-65.0
-195.8
-4.4

Free gas
997A-42X-2
329.0

95.8
142
0.0
1.7
0.4
4.2
6730
-68.2

-11.7

Hydrate gas
997A-42X-3
331.0
139
204
167
98.4
196
3.8

1.6
4940
-65.8
-196.1
-21.2

Free gas
997A-43X-1
337.1

73.9
143
20.0
23.4
6.2
26.1
4520
-65.0

-6.5

Sample type	Hole, core, section	Depth (mbsf)	Volume gas/ volume water	Volume gas/ volume water (chlorinity correction)	Chlorinity (mM)	C₁ (%)	C₂ (ppmv)	C₃ (ppmv)	i-C₄ (ppmv)	n-C₄ (ppmv)	CO₂ (%)	C₁/C₂+C₃	¹³C C₁(PDB)	D C₁(SMOW)	¹³C CO₂(PDB)	D H₂O (SMOW)
Gas tube	994A-30X-5	246.8				83.6	64	32.2	13.8	4.6	16.4	8670	-68.1		-5.3
Gas tube	994A-31X-5	257.3				93.9	86	2.0			2.8	10670
Free gas	994C-31X-3	255.1				92.0	125	0.0	14.3	3.3	8.0	7330
Hydrate gas	994C-31X-7	260.0	154	173	57	98.8	86	2.0	0.0	0.0	1.2	11230	-67.0		-5.7
Hydrate gas	996A-1H-1	0.1				99.3	1010	12.0	1.2	0.7	0.4	970
Free gas	996A-8H-3	50.3				99.3	629	28.2	11.1	2.5	0.8	1510
Hydrate gas	996A-8H-4	52.5				99.8	772	0.5	0.0	0.0	0.1	1290	-69.3		-23.2
Free gas	996A-8H-5	52.8				99.8	697	19.5	4.5	1.0	0.2	1390
Hydrate gas	996A-9H-CC	63.8				99.9	754	6.8	1.7	0.7	0.0	1310	-67.4		-19.9
Hydrate gas	996B-1H-1	2.1	43	58	169	99.3	969	11.9	2.5	0.6	0.6	1010		-199.7		13.8
Hydrate gas	996B-1H-1	2.1	18	29	248	99.4	753	8.9	1.7	0.4	0.5	1310				10.4
Hydrate gas	996C-1H-1	2.3	45	78	294	99.3	719	7.3	1.6	0.5	0.4	1370				9.2
Hydrate gas	996C-1H-1	2.3	58	90	245											10.3
Hydrate gas	996-C-2H-CC	2.4	24	48	352	99.8	857	15.8	4.3	0.9	0.0	1140	-65.9		-26.9	8.1
Free gas	996D-4H-5	26.9				98.5	720	6.5	1.8	0.6	1.5	1360
Hydrate gas	996D-5X-CC	32.1	59	107	317	99.7	747	18.3	3.2	0.8	0.3	1300				12.9
Free gas	996D-6H-4	45.0				98.9	776	22.3	5.6	1.9	1.0	1240
Hydrate gas	996D-6H-5	45.9				99.6	744	10.9	2.4	0.6	0.3	1320	-66.6	-175.0	-22.3
Free gas	996E-7X-5	48.5				98.1	637	20.4	6.2	1.6	1.9	1490
Hydrate gas	996E-7H-CC	58.6	142	145	21	99.7	719	6.9	1.6	0.4	0.2	1370	-70.7	-193.1	-21.9	17.1
Free gas	997A-41X-3	321.8				76.4	138	15.8	18.4	6.4	23.5	4980	-65.0	-195.8	-4.4
Free gas	997A-42X-2	329.0				95.8	142	0.0	1.7	0.4	4.2	6730	-68.2		-11.7
Hydrate gas	997A-42X-3	331.0	139	204	167	98.4	196	3.8			1.6	4940	-65.8	-196.1	-21.2
Free gas	997A-43X-1	337.1				73.9	143	20.0	23.4	6.2	26.1	4520	-65.0		-6.5