Table 1. Compositional and isotopic data for PCS gas samples.

Sample	Depth (mbsf)	Gas volume (mL)	CH4 (ppm)	CH4 volume (mL)	13C (CH4) (PDB)
164-994C-27P	223.50
G2		--	231,900	--	-67.0
G3		--	393,800	--	-67.9
164-994C-36P	300.40
G2		--	225,000	--	-61.1
164-994C-60P	541.10	--	228,400	--	-64.3
164-994C-70P	569.90	--	789,800	--	-63.0
164-995A-27P	222.90
G1		105	19,400	2.0	-71.3
G2		860	837,000	719.8	-67.7
G3		840	953,700	801.1	-68.2
G5		920	914,100	841.0	-69.3
G6		560	912,100	510.8	-68.4
				Weighted avg.:	-68.4
				Weighted std. dev.:	0.6
164-995A-36P	300.30
G1		80	24,700	2.0	-71.4
G2		290	579,100	167.9	-65.9
G3		590	970,200	572.4	-66.0
G4		350	966,500	338.3	-65.0
				Weighted avg.:	-65.7
				Weighted std. dev.:	0.5
164-995A-45P	377.50
G1		100	400	0.0	-73.5
G2		175	50,900	8.9	-64.9
G3		700	--	--	-63.9
G8		170	--	--	-63.9
164-995A-48P	396.80
G1		85	40,900	3.5	-65.0
G2		40	146,500	5.9	-65.0
G3		425	610,100	259.3	-63.9
G4		140	664,900	93.1	-63.4
				Weighted avg.:	-63.8
				Weighted std. dev.:	0.3
164-995A-60P	493.10
G1		70	7,200	0.5	-67.3
G2		640	195,700	125.2	-65.2
G3		325	--	--	-64.2
G4		275	--	--	-63.4
164-995B-7P	308.51
G6B		--	--	--	-65.3
G7B		650	--	--	-65.1
164-996A-7P	47.50
G3		35	31,300	1.1	-69.4
G4		45	542,500	24.4	-69.3
G6		90	864,000	77.8	-68.7
G8		300	986,000	295.8	-68.8
G16		490	948,700	464.9	-68.0
G17		600	964,800	578.9	-68.4
G19		520	972,700	505.8	-68.4
G22		280	983,500	275.4	-70.6
G24		335	932,400	312.4	-68.5
				Weighted avg.:	-68.6
				Weighted std. dev.:	0.7
164-996D-7P	51.20
G5		620	996,800	618.0	-69.1
G7		215	956,000	205.5	-68.0
G9		1060	984,400	1043.5	-68.3
G10		525	988,900	519.2	-69.3
G11		525	990,500	520.0	-66.0
G12		650	953,500	619.8	-66.8
G13		440	968,000	425.9	-66.3
G14		990	941,400	932.0	-67.6
G15		550	--	--	-67.6
				Weighted avg.:	-67.8
				Weighted std. dev.:	1.1
164-997A-25P	202.40
G1		45	3,187	0.1	-69.1
G2		15	24,448	0.4	-68.4
G3		660	954,449	629.9	-67.9
G4		340	948,136	322.4	-67.3
				Weighted avg.:	-67.7
				Weighted std. dev.:	0.3
164-997A-49P	394.90
G1		110	2,726	0.3	-62.4
G2		55	672,426	37.0	-64.1
G3		540	923,753	498.8	-64.0
G4		540	950,344	513.2	-64.8
G5		290	929,239	269.5	-64.4
G6		305	897,917	273.9	-64.2
G7		685	905,328	620.1	-64.6
G8		1190	931,182	1108.1	-64.2
G9		535	873,598	467.4	-64.7
G10		165	512,814	84.6	-64.7
				Weighted avg.:	-64.4
				Weighted std. dev.:	0.3
164-997A-55P	433.30
G1		440	745,193	327.9	-64.7
G2		690	903,547	623.4	-64.1
G3		670	920,593	616.8	-64.0
G4		560	927,895	519.6	-64.3
G6		565	949,175	536.3	-64.9
G7		630	949,178	598.0	-63.9
G9		280	928,040	259.9	-63.6
				Weighted avg.:	-64.2
				Weighted std. dev.:	0.4
164-997B-10P	462.20
G3		780	--	--	-63.3
G4		465	923,647	429.5	-63.5
G5		105	--	--	-63.2
G6		105	924,586	97.1	-64.6
G7		465	929,592	432.3	-63.0
G8		465	917,494	426.6	-64.4
G9		445	900,842	400.9	-63.5
G10		575	894,195	514.2	-63.2
G11		140	871,929	122.1	-65.0
				Weighted avg.:	-63.6
				Weighted std. dev.:	0.6
164-997B-15P	501.80
G2		500	874,613	437.3	-64.4
G3		1160	860,744	998.5	-63.1
G4		510	878,845	448.2	-63.4
G5		430	850,141	365.6	-65.5
G6		525	874,108	458.9	-63.2
G7		20	976,319	19.5	-65.0
				Weighted avg.:	-63.7
				Weighted std. dev.:	0.9
164-997B-21P	549.90
G1		85	17,517	1.5	-64.3
G2		85	8,006	0.7	-64.2
G3		390	915,858	357.2	-63.1
G4		960	957,771	919.5	-63.0
G5		625	924,014	577.5	-62.7
G6		530	890,910	472.2	-63.3
G7		440	893,655	393.2	-62.8
G8		340	--	--	-62.0
				Weighted avg.:	-63.0
				Weighted std. dev.:	0.2

Notes: -- = not measured. Successive aliquots of gas removed from each PCS core were numbered sequentially as G1, G2, G3, etc.