Table 10. Results of headspace gas analyses of sediments from Hole 1080A.
Core, section,
interval (cm)
Depth
(mbsf)
C1
(ppmv)
CO2
(ppmv)
C2=
(ppmv)
C2
(ppmv)
C3
(ppmv)
C1/C2
175-1080A-
1H-2, 0-5 1.50 2 864



1H-3, 0-5 3.00 7.4 1,893



2H-2, 0-5 4.80 228 9,058 0.2 2.1
109
2H-3, 0-5 6.30 4,352 14,123 0.3 4.5
967
2H-4, 0-5 7.80 13,099 18,397 0.6 7.2 0.8 1,819
2H-5, 0-5 9.30 20,309 12,152 0.7 8.5 1.2 2,389
2H-6, 0-5 10.80 31,121 13,778 0.2 10.9 1.3 2,855
3H-2, 0-5 14.35 11,025
1.0 6.0 1.5 1,838
3H-3, 0-5 15.90 6,842 18,213 1.7 6.8 3.0 1,006
3H-4, 0-5 17.45 10,556
0.3 6.8 2.1 1,552
3H-5, 0-5 19.00 5,485 11,171 0.5 4.1 1.1 1,338
3H-6, 0-5 20.55 9,351
0.3 6.0 1.8 1,558
3H-7, 0-5 22.10 12,959 9,367 0.4 8.2 2.5 1,580
4H-3, 0-5 24.14 6,827
0.3 5.0 1.9 1,365
4H-4, 0-5 25.64 6,684 10,766 0.4 3.6 1.0 1,857
4H-6, 0-5 27.30 7,158
0.5 6.0 2.3 1,193
4H-8, 0-5 28.91 4,458
1.4 5.1 2.6 874
4H-10, 0-5 30.71 6,333 15,641 0.9 7.1 3.7 892
4H-12, 0-5 32.41 16,069
0.8 10.9 3.7 1,474
5H-3, 0-5 34.02 4,999 16,914 1.2 4.8 2.6 1,041
5H-5, 0-5 36.10 6,021
1.2 3.9 3.0 1,544
5H-7, 0-5 38.50 6,220 20,790 1.3 3.6 3.1 1,728
5H-8, 0-5 39.70 7,196
1.8 4.6 4.1 1,564
5H-9, 0-5 40.90 8,257 24,275 1.1 3.6 3.3 2,294
5H-10, 0-5 42.10 6,611
0.1 4.4 2.9 1,502
6H-3, 0-5 43.14 5,787 29,362 1.1 5.0 6.9 1,157
6H-5, 0-5 45.54 9,881
1.1 6.4 7.0 1,544
6H-6, 0-5 46.94 11,664
1.4 16.1 4.5 7,24
6H-7, 0-5 48.34 10,759 30,280 1.0 6.4 5.7 1,681
6H-8, 0-5 49.74 7,458 24,423 0.2 3.5 3.0 2,131

Notes: C1 = methane; CO2 = carbon dioxide; C2= = ethene; C2 = ethane; and C3 = propane. Dominance of C1 over C2 indicates that the gases originate from in situ microbial degradation of organic matter.