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