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Carson, B., Westbrook, G.K., Musgrave, R.J., and Suess, E. (Eds.), 1995Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 146 (Pt. 1)
31. DATA REPORT: MOLECULAR AND STABLE ISOTOPE ANALYSES OF SORBED AND FREEHYDROCARBON GASES OF LEG 146, CASCADIA AND OREGON MARGINS1
Michael J. Whiticar2 and Martin Hovland3
INTRODUCTION
The collection and analysis of sediment gases, including light hy-drocarbons, sulfur, and permanent gases, is a required routine duringOcean Drilling Program (ODP) drilling operations with the JOIDESResolution. These measurements are a critical component of the ship-board safety and environmental protection conducted by the ship-board organic geochemists and ODP geochemistry technical staff. Inaddition, these gas analyses, in particular the hydrocarbons, are avaluable measurement asset for various scientific aspects of ODP in-vestigations. This is because these gases are ubiquitous and diagnos-tic for many subsurface processes. For example, during Leg ODP 146on the basis of determinations of the Cj-Cg hydrocarbons (methanethrough hexane) it was possible to:
1. Differentiate between the occurrences of bacterial and ther-mogenic gases;
2. Identify autochthonous vs. allochthonous (i.e., migrated)gases;
3. Signal the approach and presence of free gases (e.g., associatedwith gas hydrate dissociation);
4. Pinpoint active fractures or fault zones or seepages with fluidand/or gas flow; and
5. Define the subsurface diagenetic and catagenetic regimes.
The shipboard characterization of the gases is based on concentra-tion and molecular ratios, obtained by gas chromatography (GC).However, a more reliable classification of hydrocarbons found unex-pectedly involves the shore-based determination of the stable carbonisotope ratios of the hydrocarbons, particularly methane. The combi-nation of 2H/'H and 13C/12C ratios of methane are especially powerfulat discriminating between bacterial, thermogenic, geothermal, hydro-thermal, and abiogenic methane (Fig. 1). In concert with the molecu-lar and concentration data, the 13C/12C ratios of light hydrocarbonscan also identify secondary alterations such as mixing or microbialoxidation (Fig. 2).
Additional gas characterization with molecular and stable carbonisotopes is provided by differentiating (1) dissolved or free gases inthe interstices of the sediment from (2) the gases bound or sorbed onthe organics and minerals in the sediments. Over the past 15 years,the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR-meth-od) Hannover, FRG has pioneered the development of measurementmethodologies and interpretative schemes to take advantage of thegas genetic information contained in both the free and sorbed phasesin sediments (e.g., Faber and Stahl, 1984). The use of sorbed and freegas analyses has been applied successfully on several ODP legs, in-
-120
ES lGtLT' ll
carbonatereduction_ _
Bacterial \ " „ " 'mettiyl-tyóe * r —lermenlali..
',"" early mature '!"Tftérmpger>io
-450 -350 -250 -150δD-methane (%o)
Figure 1. Gas classification diagram using the combination of stable carbon
and hydrogen isotope ratios of methane (after Whiticar, 1990).
eluding Legs 104 (Whiticar and Faber, 1989), 112 (Whiticar andSuess, 1990), and 139 (Whiticar et al., 1994).
This is a data report of the light hydrocarbons encountered duringdrilling on the Cascadia and Oregon Margins. Some of this informa-tion is contained in the individual site chapters in the Initial Reportsvolume of Leg 146 (Westbrook, Carson, Musgrave, et al., 1994).Here, we document and make available our new shore-based data,which include:
1. Ratios of 13C/12C methane for selected Vacutainer samples(free gas);
2. Development of a new sorbed/total gas extraction apparatus, inconjunction with this ODP Leg 146 investigation;
3. Concentrations of total methane in sediments by acid-vacuumgas desorption; and
4. Ratios of 13C/12C total methane from desorbed sediment sam-ples.
Detailed interpretation and reporting of these and other geochem-ical results will be provided in the companion synthesis paper ofWhiticar et al. (this volume).
METHODS
'Carson, B., Westbrook, G.K., Musgrave, R.J., and Suess, E. (Eds.), 1995. Proc.ODP, Sci. Results, 146 (Pt. 1): College Station, TX (Ocean Drilling Program).
2 School of Earth and Ocean Sciences, University ofVictoria, P.O. Box 1700, Victo-ria, British Columbia V8W 2Y2, Canada.
3Statoil, P.O. Box 300, N-4001, Stavanger, Norway.
The techniques used to collect and analyze the sediment gas dur-ing shipboard operations are described in Shipboard Scientific Party(1994, p. 30). These will be presented briefly here, along with a de-scription of the new mechanical acid-vacuum gas desorption devicefor sorbed/total gas analysis.
DATA REPORT
Figure 2. Three-dimensional natural gas classificationdiagram using the combination of stable carbon iso-tope ratios of methane, molecular C]/(C2+C3) ratios,and gas concentration (after Whiticar, 1990).
10
-100 -70 -60 -50δiac-methane (‰)
Sampling and Measurement for Headspaceand Vacutainer Gases
During Leg 146, the compositions and concentrations of hydro-carbons and other gases were monitored in the sediments generally atintervals of one per core. Briefly, the two methods used are:
1. Headspace (HS) method:a. 5-mL sediment core taken with a cork borer and sealed into
a serum vial;b. vial warmed to 60°C;c. aliquots of gas released by the sediments analyzed by GC.
2. Vacutainer (V) or expansion void gas (EVG) method:a. samples taken on catwalk into pre-evacuated glass Vacu-
tainers when gas pockets or expansion voids occurred incores as they arrived on deck;
b. aliquots of gas analyzed by GC.
Gas Chromatographic Systems
The two systems used were the (1) Hach-Carle AGC Series 100(Model 211), a standard packed column isothermal flame ionizationdetector (FID) GC, attached to Hewlett-Packard Model 3393A Inte-grator; and (2) the Hewlett-Packard 5 890A Natural Gas Analyzer,modified by John Booker & Company, Austin, Texas, modified mul-tivalve and multicolumn, temperature-programmed GC equipped
with both thermal conductivity (TCD) and FID, and two Hewlett-Packard Model 3393A Integrators dedicated to the TCD and FID.
Sampling and Measurement for Total and Sorbed Gases
Sediment samples for the sorbed and total hydrocarbons were ob-tained from the sediments collected for interstitial fluids (see Ship-board Scientific Party, 1994, p. 32). The sediment was frozenimmediately after subsectioning and stored frozen until analysis.
The previous BGR-method used to desorb gases from sedimentsrequired 100-200 of sediment and a bulky glass vacuum extractionline (Faber and Stahl, 1984). This was necessary in order to obtain atleast 50 nmol of CH4 for the 13C/12C determination by conventionalisotope ratio mass spectroscopy (IRMS). With the development ofthe on-line, gas chromatograph/combustion/isotope ratio mass spec-trometer (GC/C/IRMS) (Fig. 3), we are now able to measure 13C/12Con extremely small quantities of methane (-100 picomole, Whiticarand Cederberg, in press). This reduction in the amount of gas re-quired also reduced the amount of sediment need to be degassed, andhence the degassing apparatus. Details of the new method are report-ed by Whiticar (in press).
Figure 4 shows the new sorbed gas desorption device. It consistsof a thick-walled glass reaction vessel, with a three-port lid sealed byan O-ring/clamp. The lid provides for a transducer measurement ofpressure/vacuum, and a valve-septum arrangement for addition of so-lutions and removal of gas samples. The procedure is briefly de-scribed below.
GasChromatograph Combustion
Isotope RatioMass
Spectrometer
Gas microinletand
Cryofocusing
Figure 3. Basic schematic of GC/C/IRMS instrumen-tal configuration for stable carbon isotope ratios ofVacutainer and total methane (after Whiticar andCederberg, in press).
Computer fordata collection
& reduction
DATA REPORT
Vacuum
Pressure/vacuumtransducer
Degassedsaline solution
pie isotope ratio relative to a known standard isotope ratio. The usualδ-notation generally used in the earth sciences is:
Acid, KOHinjection
• Gas removal
O-ring
Pressureguage
Glassreactionvessel
èediment;slurry
.Disaggregation/boiling beads
Figure 4. Light hydrocarbon acid/vacuum sediment gas desorption device(after Whiticar, in press).
A known weight of frozen sediment, typically 1-5 g wet sedi-ment, is thawed under vacuum in the apparatus. Enough saline solu-tion (degassed water saturated with NaCl) is added to make a slurryusing a vortex mixer. Phosphoric acid is added slowly to release thesorbed gas fraction into the headspace. At the same time some car-bonates will dissolve and generate free CO2. It is the carbonate con-tent of the sediment, and hence amount of CO2 released that limits thepractical sample size. The vessel is immersed in a water bath and theslurry is brought to a boil under reduced pressure (~75°C, 200 mbar).KOH is added to precipitate the CO2, leaving the desorbed hydrocar-bons and some N2, O2, CO2, H2O, and possibly H2S in the headspaceof the reaction vessel. The vessel is brought to atmospheric pressurewith degassed saline solution. Aliquots of gas are taken for analysis.Gases are then analyzed by conventional GC or by GC/C/IRMS. Atour current stage of the method development, it is still possible that aportion of the free gas could be contained in the sorbed gas fraction.Because of this, we refer to this analysis at this stage as a total gasanalyses. Continued evolution of this method will effectively elimi-nate the free gas fraction.
Concentration Units and Notation
The gases measured by the headspace and Vacutainer/EVG meth-ods are reported on a gas volumetric basis, in parts per million by vol-ume (ppmv), e.g., µl CH4/L sample. In the case of the Vacutainer/EVG the partial pressures of the gases measured are similar to thosein the gas pocket of the sediment core liner. Inherent in the samplingfor the headspace measurement, there is considerable contaminationof air in the vial prior to sealing. Hence, the abundances are only pro-portional or relative. The concentration of methane in the sorbed gas-es is reported on a wet-sediment weight basis, i.e., µg CH4/kg wetsediment (ppb wt).
Stable Isotope Notation
For practical reasons, stable isotope data are determined as a ratio,for example, 13C/12C, rather than as an absolute molecular abundance,and are reported as the magnitude of excursion in per mil of the sam-
,, " C / Csample — ( C ) / Cstandard ,δ'3C(%0) = ,/ ^ ' ×103
LV L. standard
(1)
where the 13C/12C isotope ratio is referenced relative to the PDBstandard.
RESULTS
Only the basic analytical results are presented in the following ta-bles and figures. Readers interested in interpretative aspects and dis-cussion regarding the data should refer to Whiticar et al. (in press andthis volume), and Hovland et al. (this volume).
Hole 888B, Cascadia Margin
The results of the headspace, Vacutainer, and total gas analysesfor Hole 888B are presented in Tables 1-3, respectively. Representa-tive depth plots for the methane concentrations and δ1 3Cm e t h a n e areshown in Figures 5 and 6.
Hole 889A, Cascadia Margin
The results of the headspace, Vacutainer, and total gas analysesfor Hole 889A are presented in Tables 4-6, respectively. Representa-tive depth plots for the methane concentrations and δ1 3Cm e t h a n e areshown in Figures 7 and 8.
Hole 891B, Oregon Margin
The results of the headspace, Vacutainer, and total gas analysesfor Hole 89IB are presented in Tables 7 and 8. Representative depthplots for the methane concentrations and δ1 3Cm e t h a n e are shown in Fig-ures 9 and 10.
Site 892, Oregon Margin
The results of the headspace, Vacutainer, and total gas analysesfor Site 892 are presented in Tables 9-11, respectively. Representa-tive depth plots for the methane concentrations and δ1 3Cm e t h a n e areshown in Figures 11 and 12.
ACKNOWLEDGMENTS
We would like to thank F. Harvey-Kelly for the desorption labo-ratory work and T. Cederberg for operation of the GC/C/IRMS. Thesorbed gas analyses were supported by a Nordic Research grant toM.H. The GC/C/IRMS facility was funded largely by a grant toM.J.W. by NSERC Strategic (STR0118459) and Operating(OPG0105389) Grants.
REFERENCES
Faber, E., and Stahl, W., 1984. Geochemical surface exploration for hydro-carbons in North Sea. AAPG Bull, 68:363-386.
Shipboard Scientific Party, 1994. Explanatory notes. In Westbrook, G.K.,Carson, B., Musgrave, R.J., et al., Proc. ODP, Init. Repts., 146 (Pt. 1):College Station, TX (Ocean Drilling Program), 15^8.
Westbrook, G.K., Carson, B., Musgrave, R.J., et al., 1994. Proc. ODP, Init.Repts., 146 (Pt. 1): College Station, TX (Ocean Drilling Program).
Whiticar, MJ., 1990. A geochemical perspective of natural gas and atmo-spheric methane. In Durand, B., and Behar, F. (Eds.), Advances in
441
DATA REPORT
Organic Geochemistry 1989, Part I. Organic Geochemistry in PetroleumExploration. Org. Geochem., 16:531-547.
-, in press. An acid/vacuum micro-extraction device for molecularand stable isotopic analysis of free and sorbed sediment gases. Anal.Chem.
Whiticar, MJ., and Cederberg, T., in press. Stable carbon isotope determina-tions of hydrocarbon gases at the picomole level by GC-C-IRMS.Anal. Chem.
Whiticar, MJ., and Faber, E., 1989. Molecular and stable isotope composi-tion of headspace and total hydrocarbon gases at ODP Leg 104, Sites642, 643, and 644, V0ring Plateau, Norwegian Sea. In Eldholm, O.,Thiede, J., Taylor, E., et al., Proc. ODP, Sci. Results, 104: College Sta-tion, TX (Ocean Drilling Program), 327-334.
Whiticar, MJ., Faber, E., Whelan, J.K., and Simoneit, B.R.T., 1994. Ther-mogenic and bacterial hydrocarbon gases (free and sorbed) in MiddleValley, Juan de Fuca Ridge, Leg 139. In Mottl, MJ., Davis, E.E., Fisher,A.T., and Slack, J.F. (Eds.), Proc. ODP, Sci. Results, 139: College Sta-tion, TX (Ocean Drilling Program), 467^77.
Whiticar, MJ., and Suess, E., 1990. Characterization of sorbed volatilehydrocarbons from the Peru margin, Leg 112, Sites 679, 680/681, 682,684, and 686/687. In Suess, E., von Huene, R., et al., Proc. ODP, Sci.Results, 112: College Station, TX (Ocean Drilling Program), 527-538.
Date of initial receipt: 12 September 1994Date of acceptance: 12 April 1995Ms 146SR-212
Table 1. Headspace analyses for Hole 888B.
Core, section,interval (cm)
1H-1,5-551H-1, 58-1081H-1, 111-1611H-2, 164-2141H-3, 0-51H-3, 50-532H-4, 50-532H-6, 0-53H-5, 0-54H-5, 0-55H-5, 0-56H-6, 0-57H-5, 0-58H-5, 0-59H-4, 0-59H-4, 147-15010H-5, 0-511H-2, 0-5HH-3,0-512H-3, 0-513H-4, 0-514H-5, 0-515H-3, 0-516H-6, 0-517H-5,0-518X-5.O-519X-5, 0-520X-1,0-521X-l,0-224H-2, 0-525H-4, 0-526H-2, 0-526H-4, 0-527H-5, 0-528H-2, 0-529H-4, 0-530H-1, 145-1503OH-5, 0-531H-6, 0-534H-1, 127-13034H-5, 0-535H-4, 0-535H-5, 0-536H-2, 65-7037H-7, 36-4040H-3, 0-541X-l,0-542X-1,2-343X-1,0-544X-3, 145-15045X-2, 0-547X-1,0-248X-1,0-550X-1,20-2452X-1,20-2553X-1,48-5354X-2, 0-555X-1,0-556X-1,40^1557X-1, 137-14058X-2, 145-15059P-1,0-559P-1,47-4860X-1.0-561X-1, 145-15062X-2, 0-563X-2, 0-564X-2, 0-565X-4, 145-150
Depth(mbsf)
0.30.81.43.433.5
11132131405159697778889394
104113124131145153162172175185214222
236240245256
267275294
305307312329351357367376190
397414424443452461471478
498508514514515524533542551564
O2
6265
1,49070
27,73618,4792,5346,8624,3302,536
933,6222,4592,572
21,12593
1,7016,6661,557
240,91613,635
302,31339,868
1,3134,224
22,5741,6333,873
245,7921,8776,3338,519
86422,35718,5183,231
238,0362,434
347,059171,925
1,1746,7904,570
409.891290,869
3,903126,04620,811
356,547582,869572,548503,233404,321
1,83841
1,13615,3213,391
24,508510,48
1,12018,2634,150
17,6562,1096,4379,390
20,984
N2
380402
1,388428
116,76080,0244,991
31,14416,1484,803
5688,7094,2244,609
89,807570
1,53928,959
1,402
59,395
165,7771,224
14,06195,665
2,56611,831
2,25628,80338,199
92195,0144,5707,809
4,466
1,13631,27018,653
1
12,11429,81289,179
2,080250
1,13666,5707,761
103,165208,69
1,06177,18213,89874,5103,204
27,28540,15288,681
CH4
1.20.92.01.43.23.86.24.13.34.02.71.54.44.11.00.4
110.5150.991.2
4.40.80.70.40.71.50.20.33.60.3
438.4622.5
5,997.25,930.96,710.46,862.54,120.92,447.86,238.63,969.28,586.78,967.18,059.9
23,241.04,123.06,525.2
68,043.014,107.0
950.133,329.020,264.0
8,309.510,031.028,517.05,017.15,199.9
13,918.01,342.48,978.45,718.5
18,712.024,246.6
2,952.1582.7
19,026.018,223.02,189.8
11,704.02,848.02,850.0
CO2
373158433
24,954
3,73395
1,38596
39
52
24,735
4,7951,3845,1569,014
824,744
771,279
63
49319029
4193,640
491,025
773,327
9414,0934,0623,6671,1071,2362,1292,955
513,0702,331
561,5811,0585,3811,129
4,0126,002
80686
1,888
622
155
372,616
C2H6
1.01.2
1.41.32.2
C3H6
0.7
c,/c2
1E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+620,00615,1231E+68,5872,2431,272
C,/C2+
1E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+61E+620,00615,1231E+68,5872,243986
442
DATA REPORT
Table 2. Vacutainer analyses for Hole 888B.
Core, section,interval (cm)
Depth(mbsf) CO. nC, nCs
nC= c,/c2+
31H-3, 100-10336H-7, 0-144H-3, 38-3944H-4, 143-14462H-3, 108-109
271.82319.01398.89401.44535.79
2,851.6
19,669453,492
27.4
5,865
84,902380163.3
65.5550
586,879173,705450,158
55.1373.2
951600
9.1
1.65
14.673.4
23.57
1.4
2.6
1
2.2 1.1 3.97E+ 11.00E + 64.00E + 45.11E + 41.91E + 4
4IE+ 0633,98351,09018,321
Table 3. Total gas analyses for Hole 888B.
Core, section,interval (cm)
Depth(mbsf)
CH4 (ppb)ng CH4/gsediment
61 3CH4
(‰)
3H-2, 145-1508H-4, 140-1509H-3, 140-1509H-3, 140-15010H-4, 140-15011H-3, 142-15214H-4, 138-15018H-4, 135-15024H-1, 135-15024H-1, 135-15034H-2, 130-15034H-2, 130-15034H-2, 130-15036H-2, 70-8048X-CC, 0-561X-1, 1-1063X-2, 130-15063X-2, 130-15065X-5, 0-25
1868.476.476.487.495.3
124159214.3214.3293.7293.7293.7312.2423.5522.8543.2543.2564.1
1973092X4156231203151L93171993129
631350409253414204
-39.8-41.8^ 3 . 2-42.1-43.2-37.5-33.9-34.5-38.7-33.4-52.4-50.7-48.8-59.9-57.4-50.3-50.6-51.7-50.4
Headspace methane (ppmv)101 "I02 103
100
4^200
300
400
500
146 888B- —Headspace CH4
-D•—Yield total CH 4
600
10 4
TTT,
105
146 888B
δ 1 3 CH 4 , total
• Headspace CH4
-30 -35 -40 -45 -50
δ13C-methane, total (%o)
-55 -60
100 -
^ 2 0 0 -
•ë 300 -
co 400 -
500 -
600101 10° 101 102 103 104 105
Headspace methane (ppmv), Total methane (ppb wt)
Figure 5. Depth distribution of headspace methane and total methane con-
centrations at Hole 888B.
Figure 6. Depth distribution of total methane carbon isotope ratio and head-
space methane concentrations at Hole 888B.
DATA REPORT
Table 4. Headspace analyses for Hole 889A.
Core, section,interval (cm)
Depth(mbsf) CO, iC, nC, C,/C2+
1H-2, 0-61H-5, 0-52H-1, 145-1502H-5, 140-1453H-1, 145-1503H-6, 6-104H-3, 0-54H-6, 0-55H-4, 0-56H-6, 0-57H-2, 0-58H-4, 0-59H-4, 0-510H-4, 150-15211H-2, 0-512H-2, 0-513H-l,0-514H-1, 148-15315P-1,45-5017X-2, 75-8018X-4, 31-3619X-3, 145-15020X-3, 133-13822X-2, 0-524X-6, 0-525X-2, 145-15026X-3, 0-528X-3, 0-530X-3, 0-531X-3, 0-532X-1, 125-13032X-3, 0-534X-2, 145-15036X-1,94-9937X-l,0-l38X-1.0-139X-1,45-5040X-3, 0-540X-4, 39-4441X-5.0-542X-1,42-4443X-2, 0-544X-1, 101-106
21.526.031.036.940.546.651.556.062.575.078.591.099.0
110.0115.0120.5127.0129.5129.5132.4144.4153.6163.0179.0195.3200.3209.8220.3230.8240.2248.0249.7260.2267.7275.2284.1293.3301.5301.5310.5319.5328.4337.2
1996
1,29594
3537934.7
4166077.941.725
2,2173,6616,0934,1439,0558,3562,103
50,12358,02325,01033,101
4,2554,0613,9652,9263,7483,1411,9862,161
60,34725,160
184,4622,522
73,52015,2834,1733,2987,872
51,38643,41316,318
114585
1,231577713491208724369481268150
3,5019,217
26,87513,47240,70236,951
3,089208,641237,429109,405140,520
15,27312,77711,8146,447
10,2497,2602,6693,223
249,019108,685860,777
4,859300,328
66,93214,1047,850
34,327212,776180,97771,628
58,98060,14950,13431,45230,62249,95311,91422,31233,12648,83023,92212,22521,412
9,65227,858
9,65276,49810,05351,18460,79846,43248,53454,75630,78447,33048,66247,19271,22245,85974,88210,04210,05516,27123,29934,00442,40210,07725,61926,46338,529
8,92944,39029,687
1.23.62.2
4,3863.27
823.165.547.91665.5
7.31.3
23.539.3
1,6621,9211,6341,7701,8983,6446,3251,9231,7581,3833,7923,1853,3002,035
33,2293,294
9821,824
10,2992,4491,0541,8981,8112,4871,124
9632,1092,233
1.41.52.41.31.61.91.11.62.42.92.41.12.32.24.62.2
14.111.233.420.212.519.2512.69.5
22.31620.533.338.835.912.7812.1524.7535.6635.348.935.858.3
13483
108.9110.1225.2
0.351.660.550.60.73.41.72.22.71.91.3
1.061.70.591.40.810.721.61.11.60.991.4
3.61.90.9
42,12940,09920,88924,194
8,7497,805
10,83113,94513,80316,838
11,1149310
4,3876,0564,3875,425
8981,5322,9593,2792,4514,1483,0181,8422,7492,0791,9781,1272,013
786828630624947
275434195458
81400131
Table 5. Vacutainer analyses for Hole 889A.
Core, section,interval (cm)
1H-1, 41-424H-2, 132-1335H-7, 37-389H-8, 91-9212H-5, 5-619X-3, 140-1412OX-3, 90-9122X-6, 28-2925X-2, 100-10126X-4, 56-5728X-4, 101-10230X-2, 81-8231X-5, 51-5240X-1, 102-10341X-4, 35-36103/VAC7000004/1103/VAC7000004/2103/VAC7000004/3103/VAC7000004/4103/VAC7000004/1103/VAC7000004/2
Depth(mbsf)
20.451.382.2113.1125.1144.5162.5185.3199.8211.9222.8230.1243.7302.5315.4
Type
VVVVVVVVVVVVVVV
Lab standardLab standardLab standardLab standardLab standardLab standard
c,812,418.7962,874.0995,485.3562,284.0464,676.0782,283.9969,920.4892,816.0798,851.4867,673.0813,107.7894,792.1733,235.5218,779.0860,362.1700,000.0700,000.0700,000.0700,000.0700,000.0700,000.0
c2
31.865.883.562.7
211.7607.2522.7866.9687.4625.4867.3775.7412.2206.1
2,813.587,500.087,500.087,500.087,500.087,500.087,500.0
c3
0.30.60.61.51.02.66.79.27.76.55.14.13.71.05.0
52,500.052,500.052,500.052,500.052,500.052,500.0
Area(Vs)
8.616.319.98.89.09.45.05.37.37.0
13.011.510.08.0
14.58.7
13.87.2
11.38.7
13.8
δ 1 3 CH 4
(‰)
-84.4-66.2-61.5-57.1-56.7-53.6-50.8—49.9-50.7-50.3-51.0-53.7-54.9^ 9 . 5-47.4-36.4-36.6-37.1-36.5-36.4-36.6
Area(Vs) repl.
12.0
12.9
7.6
10.6
9.5
δ 1 3 CH 4
C‰)
-83.6
-61.5
-50.4
-53.8
^ 7 . 3
Note: repl. = replicate analysis.
444
DATA REPORT
Table 6. Total gas analyses for Hole 889A.
Core,section,
interval (cm)
5H-15H-113H-213H-224X-524X-532X-332X-332X-332X-340X-443X-243X-2
Depth
(mbsf)
102102129129198.8198.8248248248248306.47329.8329.8
Type
VFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFG
Weight
(g)frozen
sediment
9.259.158.188.184.84.87.897.896.856.852.34
12.5712.57
Area
(Vs)
3.23.96
15.4514.149.028.372.031.871.81.640.781.082.65
δ1 3CH4
(foo)
-55.2-55.1-56.8-56.8-50.8-50.7-54.2-53.5-52.9-52.8-45.2-48.0-47.3
CH4 (ppb wt)ng CH4/g frozen
sediment
488659
2,2412,0512,1211,968
271250290265409
95232
Headspace methane (ppmv)
50,000 100,000 150,000 200,000
50
100
150
250
300
350
146 88 9A- Headspace CH4 (ppmv)• Yield total CH4 (ppb wt)
50 -
100 -
150 -
200 -
250 -
300 -
350
\ F-". JB—-"•=- a'
".B
: SL... Q. -.-.-.-.-.-.-.β-:™"B
- % /: - • - 1/
Vf
•• t\
^ – - •* \
a / /
^-< /J
f>146 88 9A
....a.... Headspace CH4
— — δ 1 3 C H 4 , vac
• δ 1 3 CH 4 , total
Λ
-
-24 -32 -40 -48 -56 -64 -72 -80
δ13C-methane, vacutainer, total (%o)
Figure 8. Depth distribution of Vacutainer and total methane carbon isotope
ratio and headspace methane concentrations at Hole 889A.
101 102 103 104 105
Headspace methane (ppmv), Total methane (ppb wt)
Figure 7. Depth distribution of headspace methane and total methane con-
centrations at Hole 889A.
445
Table 7. Headspace and Vacutainer analyses for Holes 891A and B.
Core, section, Depthinterval (cm) (mbsf) O 2 N 2 CH4 CO 2 C 2H 4 C 2H 6 C 3 H 6 iC4 nC4 C,/C2
Headspace
146-891A1H-3,0-5 3.03 155,935 937,857 3 464 I E + 62H-2,0-5 6.23 171,141 928,039 3 3,492 IE + 63H-2,0-5 8.83 208,204 787,818 3 3,263 IE + 6
146-891B3X-CC, 0-2 20.81 142,183 963,534 4 1,501 IE + 64X-CC, 0-2 29.61 164,223 910,127 2 963 IE + 61 OX-1,0-5 85.13 184,210 736,677 5 2,932 I E + 611X-2,0-5 102.43 205,006 807,826 8 2,067 I E + 614X-1,59-64 110.12 196,472 838,754 7 1,157 1.6 I E + 615X-1, 1-6 118.44 105,703 1,067,457 3 275 1E + 616X-1,49-54 127.82 193,098 752,829 5 574 I E + 618X-CC, 7-9 145.18 170,089 910,598 2 2,320 I E + 619X-1.8-10 153.99 184,488 75,319 2 1,158 I E + 620X-1, 142-147 164.15 193,889 750,667 16 3,767 tr. I E + 621N-1,47-52 172.10 178,763 727,660 2 1,877 tr. I E + 622X-1,62-67 176.75 188,927 742,200 2 1,318 IE + 623X-1, 145-150 181.98 182,443 787,209 3 1,328 IE + 625X-1,56-61 198.79 171,084 731,476 2 2,550 I E + 626X-1, 10-15 207.23 146,819 1,059,769 4,658 4,133 IE + 627X-1, 10-15 216.03 205,096 806,067 944 5,463 IE + 628X-1,45-50 225.18 198,732 843,058 9,135 3,570 IE + 630X-2,85-89 239.97 191,709 827,795 10,065 629 2.0 IE + 631X-2,0-5 243.93 102,125 469,106 9,924 23,399 I E + 632X-1,20-25 251.63 164,332 772,866 40,864 13,805 0.9 44,08233X-1,20-25 260.43 171,706 713,942 31,428 6,102 I E + 634X-2,50-53 265.12 147,363 775,640 49,033 16,379 1.2 0.3 39,25835X-1, 145-150 270.48 171,123 717,895 20,321 7,018 tr. IE + 637X-1,0-4 278.82 190,979 906,506 34,758 8,407 I E + 638X-2,0-5 287.93 155,194 979,326 50,886 13,315 0.9 57,17539X-2,0-5 296.63 208,975 908,710 56,915 23,235 1.2 45,89940X-1,0-5 304.03 201,758 795,865 9,383 9,230 I E + 641X-2,0-5 314.33 116,760 507,611 25,447 94,796 4.5 3.1 4.6 6.7 5,71842X-1, 147-150 323.09 163,534 717,869 37,572 8,466 tr. I E + 643X-3.0-5 333.43 150,716 749,949 16,873 3,878 I E + 644X-1.9-14 339.42 175,525 918,771 18,593 5,739 0.7 I E + 645X-l,0-5 348.23 204,890 853,129 41,835 5,529 I E + 647X-1,65-75 366.80 123,153 615,195 10,034 27,688 0.3 1.0 tr. tr. tr. I E + 448X-1,47-49 375.48 173,957 699,399 25,524 4,346 tr. tr. I E + 649X-1,0-5 383.93 176,610 749,105 17,756 3,875 tr. tr. IE + 650X-1,0-5 392.83 140,605 649,341 17,240 1,070 tr. tr. I E + 652X-1,21-26 410.74 161,044 958,588 6,357 39,090 tr. 1.8 2.0 1.2 3.7 3,51255X-1,35^0 437.38 173,406 805,778 40,129 15,686 1.0 1.3 38,96056X-2,0-5 447.33 171,160 921,846 36,946 7,946 2.1 I E + 657X-1,48-53 455.21 203,585 860,335 33,387 13,596 I E + 658X-2,27-32 465.30 32,258 3,403 tr. IE + 6
Vacutainer
146-89 IB41X-2, 98-99 315.29 109,703 442,017 58,430 468,343 150 61.3 3.3 28.0 39042X-2,50-50 323.60 198,221 812,857 6,597 1,312 1.0 6,59747X-2,49^9 368.09 181,257 691,711 34,502 87,728 3.5 4.7 2.6 7,32555X-2, 107-108 368.68 209,046 792,808 197,281 2,579 3.5 2.4 2.6 82,200
Table 8. Total gas analyses for Hole 891B.
Weight(g) CH4 (ppb wt)
Core, section, Depth frozen Area δ'3CH4 ng CH4/ginterval (cm) (mbsf) Type sediment (Vs) (‰) frozen sediment
56X-1,72-89 446.52 VFG 1.05 0.5377 -50.7 563.155X-2, 130-150 438.97 VFG 1.41 0.8087 -63.4 659.555X-2, 130-150 438.97 VFG 1.41 0.7478 -64.0 609.852X-1,7-21 410.57 VFG 1.09 0.3444 -38.7 427.752X-1,7-21 410.57 VFG 1.09 0.3207 -39.4 398.343X-1, 10-27 330.50 VFG 1.36 0.5119 -44.2 446.943X-1, 10-27 330.50 VFG 1.36 0.4754 -42.9 415.041X-1, 135-150 314.15 VFG 0.81 0.3543 -42.6 530.921N-CC, 0-5 172.12 VFG 1.64 0.2148 -42.7 197.115X-1,82-90 119.22 VFG 1.37 0.474 -37.7 461.5Standard V 14.5567 -36.6Standard V 0.971 -36.6
Note: VFG = Vacutaine Free Gas, V = Vacutainer, and Vs = GC/C/IRMS peak area mass 44 (Volt sec).
DATA REPORT
100
Iε 200
300
400
500
146 891 B— —headspace CH 4
—-B•—total CH,
10 u 101 10 2 103 104
Headspace methane (ppmv), Total methane (ppb wt)10"
10°
Headspace methane (ppmv)
102 103 104105
100
-200
400 -
Figure 9. Depth distribution of headspace methane and total methane con-
centrations at Hole 89IB.
500
146 891 BHeadspace CH4
δ 1 3 CH 4 , vac
δ 1 3 C H 4 , total
-40 -50 -60
δ13C-methane, vacutainer, total (%o)
-70 -80
Figure 10. Depth distribution of total and Vacutainer methane carbon isotope
ratios and headspace methane concentrations at Hole 89IB.
447
DATA REPORT
Table 9. Headspace analyses for Holes 892A, 892D, and 892E.
Core, section,interval (cm)
146-892A1X-2, 0-21X-4, 13-152X-3, 0-53X-1,0-53X-3, 0-54X-1,95-1006X-1, 145-1507X-6, 0-58X-3, 145-1509X-1,0-59X-1,64-6911X-2, 10-1512X-1,60-6513X-3, 96-10113X-8.0-514X-1, 6-1114X-1, 20-2515X-1, 98-10016X-1, 41-4317X-2,0-318X-2,0-520X-CC, 0-520X-2, 145-15021X-1, 7-12
146-892DlX-1,5-72X-1,0-52X-2, 0-52X-2, 145-1503X-1,0-53X-2, 0-54X-2, 0-44X-3, 30-354X-3, 95-1005X-2, 0-55X-3, 0-56X-4, 135-1407X-4, 145-1508X-3, 10-159X-4, 15-2010X-4, 15-2010X-6, 0-511X-1, 125-13012X-4, 0-514X-2, 0-515X-3, 0-516X-3, 0-5
146-892ElX-1,0-51X-1, 128-1321X-2, 125-1303H-5, 125-130
Depth(mbsf)
1.513.67
12.5319.0322.0329.4840.4856.0362.4867.5368.1779.6388.13
100.99103.45106.59106.73116.99125.92135.61146.03167.07166.48173.10
0.068.53
10.0311.4818.0319.5329.0230.8331.4838.5340.0352.3859.9864.8373.98
104.68107.53110.78123.53139.53150.53160.03
0.031.302.78
40.28
O2
161,918154,836151,045188,098176,566179,080153,340127,472103,641162,469114,746143,192167,365176,890162,343173,101147,248146,993191,269207,599
147,042116,652201,518
145,672184,162121,472144,870187,573123,895197,011117,260194,465203,576120,194160,326161,842163,236125,804
2,57560,63254,405
153,879206,460135,574142,266
42,50499,92980,713
136,336
Headspace gases from hydrate dissociation
146-892 A1X-4, 13-151X-4, 13-151X-4, 13-151X-4, 13-15
3.673.673.673.67
178,369152,440209,043165,080
N2
692,267740,766687,839757,871783,687762,634667,552698,926719,730645,999710,498704,554781,741
1,028,8481,055,523
718,681781,741686,294925,261808,947
734,007725,586788412
638,348711,913697,491673,071758,607596,837774,283565,663781,034787,825544,113666,856687,668790,548634,234
4,779260,612249,574696,886851,797638,314614,633
249,592703,422381,245261,470
in syringes
872,556598,181890,491747,892
CH4
80,252132,767129,76039,86133,94750,44738,21358,79960,32761,56410,01535,80025,29920,08161,30432,38512,53047,61719,51361,21111,85618,86828,62595309
5175,893
70,14710,06236,10418,22214,3999,5098,306
46,88336,49224,06931,14310,07838,89154,81943,75354,51155,43642,26965,074
106,913
730,75443,950
542,39057,984
66,40810,21036,02646,085
CO2
1,713578393
5,7011,6843,5332,6019,7005,4205,4205,420
3346,4514,7414,8491,1472,941
11,1384,0603,0563,0562,680
846906
543407932571
1,9342,3533,7168,4754,0974,4923,5984,0704,3351,9754,546
620125
3,2332,8933531
9635155
339771164257
866
504711274731
C2H4
tr.
1.0
0.9
tr.tr.tr.tr.tr.tr.tr.tr.
tr.
tr.
tr.tr.
tr.tr.tr.tr.
C2H6
3277
101654314341
28133926416712118624932735452530218851
106176
51
2216158
316
14233929
17237385613621408109269247
59331
44850
308
1222
H2S
tr
ti-
ll,73312,280
12,408
C3H6
0.81.96.8
39.417.035.829.423.129.458.8
116.2102.8267.5
33.950.418.133.125.6
0.40.1
5.70.10.10.6tr.0.40.60.81.23.35.8
31.3629.9576.0101.076.615.248.330.8
0.30.60.30.3
1.41.5
1.5
iC4
tr.4.55.1
32.615.838.320.428.531.547.145.150.2
109.510.2
19.735.222.9
2.2
2.5
1.89.0
41.0158.0191.3
10.936.711.98.4
19.2
0.9
2.93.3
3.1
nC4
1.8
3.431.415.4
2.6tr3.9
20.531.3
5.052.8
2.6
8.38.5
18.9
1.9
1.25.1
185.7400.0
3.02.7
3.1
21.228.4
31.0
C,/C2+
2,1721,7182,4423,9082,0951,4971,063
99088413222
103106107215
80228718
16950
148132327
944,0923,248
3092,4072,159
4491,704
4931,998
78181187430211436227197
300194345
1,2301,3841,2021,074
1,182246
3,116840
448
DATA REPORT
Table 10. Vacutainer analyses for Hole 892A.
Core, section,interval (cm)
1X-2, 27-281X-3, 55-562X-4, 114-1153X-2, 120-1214X-2, 11-126X-2, 74-746X-3, 148-1487X-7, 22-228X-4, 135-13511X-3, 26-2713X-4, 66-6715X-1,84-8417X-2, 63-6318X-2, 6-720X-1, 147-148
G.HYDRATE-V.4
103/VAC900000PPM3/4103/V AC900000PPM3/1103/VAC900000PPM3/2103/V AC900000PPM3/3103/V AC300000PPM7/16103/V AC900000PPM2/5103/V AC900000PPM2/6103/VAC300000PPM7/11103/VAC300000PPM7/12103/V AC30OOO0PPM7/14103/VAC300000PPM7/15
Depth(mbsf)
1.783.55
15.1521.7130.1241.2443.4857.7263.8581.26
102.17116.84137.13146.07164.98
StandardStandardStandardStandardStandardStandardStandardStandardStandardStandardStandard
CH4
802,197805,749724,806919,909455,003360,704851,695854,304848,342931,873949,757648,209811,411139,571390.854
800,000
900,000900,000900,000900,000300,000900,000900,000300,000300,000300,000300,000
C2
807.9818.5595.5359.0677.6446.0993.7
2,070.01,155.06,322.05,310.97,137.06,201.0
352.91,007.0
112,500.0112,500.0112,500.0112,500.037,500.0
112,500.0112,500.037,500.037,500.037,500.037,500.0
c3
1.00.62.76.1
11.132.6
273.0205.3
3,473.0332.2
29.4102.0
67,500.067,500.067,500.067,500.022,500.067,500.067,500.022,500.022,500.022,500.022,500.0
Area(Vs)
20.014.719.28.3
12.3
9.415.714.58.0
12.79.9
11.65.68.8
0.2
9.78.47.86.21.37.77.18.37.13.53.6
δ 1 3CH 4
(‰)
-66.1-67.5-66.3-66.3-67.9
-66.2-66.1-66.4-62.4-60.1-60.5-62.3-61.8-62.1
-64.8
-36.5-36.5-36.3-36.2-37.4-36.6-36.2-36.7-39.4-36.6-36.6
Area(Vs) repl.
18.3
8.9
8.621.3
10.110.113.210.620.0
8.1
0.5
δ l 3CH 4
(‰) repl.
-66.3
-66.5
-68.3-66.0
-66.1-63.5-60.1-60.5-61.2
-62.5
-64.1
Note: repl. = replicate analysis.
Table 11. Total gas analyses for Hole 892A.
Core, section,interval (cm)
20X-3,0-1020X-3, 0-1020X-3, 0-1020X-3, 0-1018X-1, 140-15018X-1, 140-15015X-1, 88-10013X-6, 69-8211X-2, 0-109X-1,69-748X-3, 0-108X-3, 0-106X-2, 0-103X-3, 0-102X-3, 0-112X-3, 0-11
Depth(mbsf)
166.5166.5166.5166.5145.9145.9116.9101.679.568.2616140.521.812.512.5
Type
VFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFGVFG
Weight
(g)frozen sediment
3.453.454.24.22.572.571.552.131.835.240.940.750.941.12.442.23
Area(Vs)
7.17896.52477.49536.85285.47442.56091.44683.47935.05776.01810.99460.87152.62920.64151.15391.3915
δ 1 3 CH 4
(%»)
-63.5-63.7-63.8-63.9-64.0-63.5-60.8-64.2-63.2-63.8-63.2-63.5-65.9-60.4-61.9-61.4
CH 4 (ppb wt)ngCH4/g
frozen sediment
2,3992,1812,2522,0592,7631,2931,1732,0893,3491,3561,3281,3353,574
688572901
444
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