Research Article Methane at the NW of Weddell Sea, · PDF fileResearch Article Methane at the...

Research ArticleMethane at the NW of Weddell Sea Antarctica

R A del Valle1 E Yermolin1 J Chiarandini2 A Sanchez Granel3 and J C Lusky2

1 Instituto Antartico Argentino 25 de Mayo 1143 San Martın Provincia de Buenos Aires Argentina2Direccion Nacional del Antartico Balcarce 290 2∘ Piso C1064ABR Ciudad Autonoma de Buenos Aires Argentina3Universidad del Salvador Av Callao y Cordoba C1023AAB Ciudad Autonoma de Buenos Aires Argentina

Correspondence should be addressed to R A del Valle kings foilhotmailcom

Received 16 August 2016 Revised 14 November 2016 Accepted 1 December 2016 Published 13 February 2017

Academic Editor Umberta Tinivella

Copyright copy 2017 R A del Valle et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of gaseous hydrocarbons (from methane to n-pentane) in the seabed sediments and the bubbling of methane maysuggest the presence of gas accumulations in the substrate of the NW Weddell Sea Antarctica The release of methane from thefrozen ocean substrate adjacent to Seymour Island would be linked to climate instability during Late Cenozoic when vast areas ofthe Antarctic continental shelf were flooded during themarine transgression that occurred 119888 18000 years ago after the Last GlacialMaximum (LGM) As the icemelted the sea again occupied the regions which it had abandoned As the transgression was relativelyrapid the sub-air relief was not destroyed but was submerged and the ground had frozen (permafrost) along with it Thus the heatflow from the sea to the marine substrate now flooded would have destabilized frozen gas accumulations which were originallyformed into terrestrial permafrost during the LGM similarly to what would have happened in the Arctic

1 Introduction

Gases that trap heat in the atmosphere are called greenhousegases and methane is one of them Methane emissions cause119888 25 of the current global warming While methane doesnot linger as long in the atmosphere as carbon dioxide itis initially far more devastating to the climate because ofhow effectively it absorbs heat In the first two decades afterits release methane is 84 times more powerful than carbondioxide [1]

11 Objectives This paper is aimed at briefly presenting anddiscussing the occurrence ofmethane gas inAntarctica undertwo facts (I) the concentrations of methane (C1) togetherwith other alkane aliphatic hydrocarbons of single bondsfrom ethane (C2) to pentane (C5) found in seabed sedimentsoff the northern coast of Seymour Island (IslaMarambio) andthe NW extreme of the Weddell Sea Antarctica (Figure 1)and (II) the natural bubbling of methane observed off theSeymour Island coast (Bouchard Zone Figure 1 see thesupplemental video in Supplementary Material availableonline at httpsdoiorg10115520175952916)

12 Working Area The research was conducted in twomarine sectors of Antarctica with different characteristicsone of shallow waters located in Admiralty Sound (EstrechoBouchard) off the northern coast of Seymour Island and theother characterized by deeperwaters located offshore at about70 km to the northeast of the island (Figure 1)

The area named ldquoBouchard zonerdquo extends about 100 km2and the area called ldquoWeddell zonerdquo about 3000 km2 Fieldactivities were developed during austral summers of 19941995 1997 1998 2011 and 2015 when the region was largelycovered by sea ice and icebergs which hampered systematicsampling in both sectors For this reason the distribution ofsamples at seabed became completely irregular (Figure 1) andthe density of samples actually is quite low

Alkane aliphatic hydrocarbons of single bonds wereanalyzed at Bouchard and Weddell zones 88 and 54samples respectively (Table 1) spread over 100 km2 and3000 km2 resulting in meager 088 sampleskm2 and 0018sampleskm2 respectively

13 Geological Frame The working area (Figure 1) is locatedwithin an Antarctic site of sedimentary accumulation James

Hindawi Publishing CorporationJournal of Geological ResearchVolume 2017 Article ID 5952916 8 pageshttpsdoiorg10115520175952916

2 Journal of Geological Research

Table 1 Summary of analyses of C1 to C5 of sediment samples from the Antarctic seabed

(a) Bouchard zone (Figure 1)

Number of samples88

C1(ppm)

C2(ppm)

C3(ppm)

C4(ppm)

n-C4(ppm)

C5(ppm)

n-C5(ppm)

Maximum 999563 4925 3671 11 64 232 028Minimum 11582 003 481 017 277 007 006Average 42331 2114 1049 4 277 066 0251119877 Maximum = 41 Minimum = 2 Average 119877 = c 232 C1 Maximum = 9989 Minimum = 6344 Average C1 = c 89

(b) Weddell zone (Figure 1)

Number of samples54

C1(ppm)

C2(ppm)

C3(ppm)

C4(ppm)

n-C4(ppm)

C5(ppm)

n-C5(ppm)

Maximum 175387 8665 6406 2275 1928 1406 491Minimum 6527 472 528 170 037 015 003Average 36960 3240 2640 755 649 290 1661119877 Maximum = 24 Minimum = 2 Average 119877 = c 72 C1 Maximum = 9515 Minimum = 70 Average C1 = c 821119877 = C1C2 + C3 2 C1 = C1 lowast 100C1 + C2 + C3 + C4 + C5

Weddell Sea

Snow HillIs

James RossIs

Antarctic Peninsula

JoinvilleIs

DundeeIs

Seymour(Marambio)

Is

Paulet Is

Sampling place Bouchard zoneSampling place Weddell zone

Fossil Bay

Loacutepez deBertodanoBay

58∘W 57

∘W

58∘W

80∘W 70

∘W

70∘W

50∘S

60∘S

64∘S

70∘S

60∘W

60∘W 50

∘W

50∘W

54∘W55

∘W57∘W 56

∘W

minus6426∘S

minus6380∘S

minus6400∘S

minus6420∘S

minus6440∘S

minus6430∘S

minus6435∘S

minus5695∘W minus5690

∘W minus5685∘W minus5680


∘W minus5665∘W





∘W

0 5 10 15 20

(km)

Figure 1 Working areas at the NWWeddell Sea Antarctica Small triangles (red triangle) indicate sampling places at Bouchard andWeddellzones Bouchard zone is enlarged due to the small scale of the map while Weddell zone is in the right scale

Journal of Geological Research 3

Ross Basin [2] which is a ldquosubbasinrdquo comprising the northernpart of a larger basin named Larsen Basin [3] that wasdeveloped behind a volcanic arc (back-arc basin) duringmost of the Mesozoic and Cenozoic periods Within thisbasin over 6000 meters of thick clastic sediments mostly ofvolcanic origin were deposited

Cretaceous and Paleogene sediments which belong toMarambio and Seymour stratigraphic groups respectivelycrop out at Seymour Island These sediments correspond tothe so-called ldquoshallow play zonerdquo described by Macdonaldet al [4] He inferred by indirect geophysical methods (ieseismic reflection profiles) that here shallow hydrocarbonreservoirs would potentially be small and contain mainly gasalthough the quality of these reservoirs would be higher thanthat at other deeper levels

Basaltic rocks of the Miocene-Recent James Ross IslandVolcanic Group (JRIVG [5]) crop out at most of the neigh-boring islands of James Ross Island Group

The permafrost layer reaches a thickness of c 250m atSeymour Island [6] Fukuda et al [7] defined at this placethree levels of marineglacimarine terraces (1) LaMeseta (2)Sub-Meseta and (3) Larsen TerraceThe former is the lowestwith 30ndash35m asl and an age of 2910 plusmn 120 years BP and wasobtained in a layer of algae from the bottom of the terrace atc 3m asl

According to Sloan et al [8] two seismostratigraphicunits would be present at the deep marine substrate ofWeddell zone (Figure 1) (1) theUnit ldquoU3rdquo (reflections dipping3∘ndash5∘E-SE Cretaceous-Oligocene) and (2) the Unit ldquoU4rdquo(chaotic reflections Jurassic vulcanites) Samples from thedeeper seabed (289ndash556m below sea level) analyzed in thisstudy were obtained in the domain of these two units ofthe substrate inferred by high resolution seismic reflectionsurveys

The study area from a structural point of view is placed tothe north of a major counterclockwise strike-slip fault zonelocated c 25ndash35 km SE of the eastern coast of Snow Hill andSeymour islands [8 9] This fracture zone is parallel to theeastern edge of Antarctic Peninsula and its origin is assignedto tectonic movements which probably occurred during theOligocene [8] Due to its relatively old age this structurewould have no influence in the present study

14 Materials and Methods The morphology of seabed atBouchard zone was carried out using a portable side-scansonar EdgeTech Discover 4150 and profiles of the substrateup to c 210m depth below seabed were obtained with aportable subbottom profiler EdgeTech Discover SB-3200-XS Both instruments were towed and operated using smallrubber boats (Zodiac Mark III) while the sampling atWeddell zone was done onboard the Icebreaker Irizar

Sediment samples were obtained with snapper and grav-ity and piston corer Benthic of 1020 kg and packaged insealed containers Benzalkonium chloride 2 was addedto inhibit bacterial action and forwarded to the laboratory[10] where all the sediment samples were analyzed for theircontents in gaseous alkanes methane (C1) ethane (C2)propane (C3) butane (C4) and pentane (C5)

Additionally samples of gas exhalations found atBouchard zone were obtained with gas trap they werepackaged in sealed containers of 4 litersrsquo capacity and sentto laboratory in order to be analyzed for their contents inmethane H

2S and CO

2

2 Results

Sediment samples from the seabed in the surroundings ofthe NE Antarctic Peninsula (Figure 1) contain small amountsof methane (CH

4) besides other aliphatic hydrocarbons of

simple bond and ice Most of the samples analyzed in thispaper (Table 1) are fine grained and generally muddy (siltyclay) and exhibit dark gray colour except those obtained atshallow areas next to the coast (Bouchard zone Figure 1)where they include sandy fractions and show lighter shadesAlso some samples from deeper water (c 300450m) inWeddell zone (Figure 1) show high contents of sand andgravel materials The latter are composed of fragments ofbasalts identified to belong to James Ross Island VolcanicGroup (JRIVG) and plutonic rocks (mainly granites) all ofthem were probably transported by icebergs (dropstones)

At Bouchard zone 88 samples from the seabed obtainedat depths between 05m and 37m were analyzed (Table 1Figures 2 and 11) The C1 (CH

4) content ranges between

115 ppm and 9995 ppm with 423 ppm in average (Table 1Figure 2) Methane (C1) is the dominant gaseous alkanehydrocarbon in all the samples (Figure 3) Four samplesshow high values of methane ranging between 51389 ppmand 999593 ppm and they are considered as strongly positiveanomalies (Figure 2) Also in all samples small amounts ofmore complex hydrocarbons from ethane (C2) to pentane(C5) (Table 1) were detected

The hydrocarbons ratio (119877 = C1C2 + C3) exhibits valuesranging between 2 and 41 whereas the percentage of C1 tototal gaseous hydrocarbons ( C1 = C1 lowast 100C1 + C2 + C3+ C4 + C5) fluctuates between 6344 and 9989 (Table 1Figure 3)

Many gas emanations (bubbling) were detected atBouchard zone where the composition of a total of six (6)gas samples yielded c 160000 ppm as an average of CH

4

with traces of H2S and CO

2(Table 2) These gas samples

were collected in shallow waters ranging 10ndash15m in depthmainly during low tides when gas emanations occur morefrequently suggesting that free gas might accumulate inshallow submarine reservoirs during high tides and escape aswater pressure decreases below certain level

The supplemental video shows the coastal environmentduring low tide in the vicinity of Seymour Island (at Bouchardzone Figure 1) located at the NW extreme of the WeddellSea Images of various natural bubbling of methane are alsoshown The water depth was about 15m and the watertemperaturewasminus16∘CThe imageswere obtained during theAntarctic summer campaign of the year 2012 The density ofthe methane leaks was estimated at approximately 1 methanevent every 20 square meters

At Weddell zone (Figure 1) 54 sediment samplesobtained at water depths of 289ndash556m were analyzed(Table 1 Figures 4 5 and 12) Methane (C1) content ranging


Table 2 Analyses of gas emanations (bubbling) at Bouchard zone (Figure 1)

Bouchard zone Analyzed gasesSamples Depth C1 (ppm) SH

2CO2

1 10ndash15m 165240 Traces Traces2 10ndash15m 169263 Traces Traces3 10ndash15m 167806 Traces Traces4 10ndash15m 166570 Traces Traces5 10ndash15m 158172 Traces Traces6 10ndash15m 156808 Traces Traces

Sample 25Sample 28

Sample 7

Sample 54

minus6420

minus6425

Latit

ude S

minus6430

minus6435

minus5695 minus5690 minus5685 minus5680 5675 minus5670 minus5665 minus5660Longitude W

Figure 2 Distribution of methane (CH4) detected in samples of seabed sediments along Bouchard zone (Figure 1) Samples 7 54 25 and 28

are considered as strongly positive anomalies they contain the maximum values of methane 9995 ppm 1753 ppm 858 ppm and 837 ppmrespectively

Samples

100

H

D

80

60

40

20

0

n-C5iso-C5

iso-C4n-C4 C1

C2C3

8681767166615651464136312621161161

Figure 3 Percentage of methane (CH4) related to total hydrocar-

bons content ( HD = C1 lowast 100C1 + C2 + C3 + C4 + C5) detectedin all analyzed samples alongBouchard zone (Figure 1) C1methaneC2 ethane C3 propane C4 butane n-C4 n-butane C5 pentaneand n-C5 n-pentane

between 6527 and 175387 ppm with 36960 ppm as anaverage was detected (Table 1 Figure 4) being the dominantgaseous aliphatic alkane in all samples (Figure 5) Samples

with high values (ie Sample 20 175387 ppm) are consideredas strongly positive anomalies Small amounts of other alkanehydrocarbons from ethane (C2) to pentane (C5) were alsodetected (Table 1 Figure 5)Values of119877 vary between 2 and 24while the values of C1 vary between 70 and 95 (Figure 5)No gas vents (flares) were observed along this sector

Reflectors compatible with lenses and discontinuousbands next to the sea floor were detected by geophysicalsurveys (see ldquoSection 14 Materials and Methodsrdquo) in thesubstrate of Admiralty Sound Antarctica (Bouchard zone)(Figures 6 7(a) 7(b) and 8) Instrumental limitations inthe survey only allowed for recognizing reflectors into thesubstrate up to a maximum of 210m depth below theseabed (Figure 8) but it is estimated that the presence ofsuch reflectors still continues below this range In this areathe maximum content of CH

4was obtained (Sample 7

999593 ppm Table 1 Figure 2) from all the samples analyzedin this paper

The distribution of the reflectors detected in the substrateat Bouchard zone is heterogeneous and apparently random(Figures 6 and 8) The horizontal trace of the geophysicalsurveys was fragmentary quite irregular and discontinuousdue to the obstacle presented by sea ice and icebergs

Images of the seabed obtained with side-scan sonar inshallow waters of Bouchard zone show a dense network oftracks and drags caused by the intense traffic of icebergs


Sample 8

Sample 1

Sample 49

Sample 20

minus6380

minus6400

minus6420

minus6440

Longitude W minus5640 minus5600 minus5560 minus5520 minus5480 minus5440

Latit

ude S

Figure 4 Distribution of methane (CH4) detected in seabed sediments alongWeddell zone (Figure 1) Samples 20 49 1 and 8 are considered

as strongly positive anomalies they contain the maximum values of methane 1753 ppm 717 ppm 709 ppm and 592 ppm respectively

H

D

Samples

100

80

60

40

20

0535047444138353229262319161310741

n-C5i-C5

i-C4n-C4 C1

C2C3


bons content ( HD = C1 lowast 100C1 + C2 + C3 + C4 + C5) detectedin all analyzed samples along Weddell zone (Figure 1) C1 methaneC2 ethane C3 propane C4 butane n-C4 n-butane C5 pentaneand n-C5 n-pentane

(Figure 9) The strong mechanical disturbance obliteratesmost of the structures formed on the seabed by the ventingof gases (ldquopockmarksrdquo) Figure 10 shows images obtainedwith portable side-scan sonar of these structures quite wellpreserved at seabed of Bouchard zone

No geophysical research was carried out at Weddellzone due to the lack of facilities and adequate instrumentalonboard the Icebreaker Irizar

3 Discussion

Methane (C1) predominates widely in sediments of theAntarctic seabed analyzed in this paper The average contentof C1 to total gaseous hydrocarbons (C1 + C2 + C3 + C4 +C5) in Bouchard and Weddell zones is c 89 and c 82respectively indicating a certain abundance of more complexhydrocarbons predominantly ethane (C2) and propane (C3)at both zonesThis is also reflected in the relatively low valuesof 119877 (ratio of [C1][C2] + [C3]) which is 2ndash41 (average value

(b)

(a)

30

50

100

AB

Dep

th(m

bsb

)

64∘12

998400382

998400998400S56

∘38

998400339

998400998400W

110m bsb

64∘13

998400338

998400998400S56

∘31

998400529

998400998400W

Towards 3182∘NE length 2km

Enlarged area

Figure 6 Reflectors compatible with solid lenses (A) and dis-continuous bands (B) recorded with sea-bottom portable profiler(EdgeTech Discover SB-3200-XS) in a sector of marine substrateup to 110m below seabed (bsb) towards the NE of Bouchard zone(Figure 1) These reflectors may correspond to methane accumu-lations frozen in the marine substrate surroundings of Seymour(Marambio) Island (Figure 1) (a) A survey sector of the marinesubstrate 2 km long and 110m depth Latitude and longitude arespecified at both the left and right corners of the profile (b) Enlargedsector of the figure (a)

equals 23) at Bouchard zone and 2ndash24 (average value equals7) at Weddell zone (Table 1)

Although there is not a definite design in the distributionof methane concentrations at Bouchard zone a gradualincrease of methane content occurs as sampling stationsmigrate northwards from the coast of Seymour Island (Fig-ure 2)

At Bouchard zone there is no relationship betweenmethane content and sea depth (Figures 11 and 12) Methaneconcentrations are lower near the coasts of Seymour Islandwhere sandy sediments predominate while they are higher inseabed sediments rich inmud generally away from this coastThis situation is also reflected in Fossil Bay (ldquoBahıa Fosilrdquo)(Figures 1 and 2) where muddy clay facies predominate andgas concentrations are relatively high In the proximities of


0m bsb

210 m bsbLat 64∘129682998400S Long 58∘388427998400W water depth 348 m

(a)

Lat64∘129584998400S Long 58∘387221998400W Water depth 35m

0m bsb

210 m bsb

A

B

(b)

Figure 7 Details of reflectors compatible with lenses (A) and solid bands (B) recorded with sea-bottom portable profiler (EdgeTechDiscoverSB-3200-XS) in a sector of marine substrate up to 210m depth below seabed (bsb) towards the NE of Bouchard zone (Figure 1) Thesereflectors may correspond to methane accumulations frozen in the marine substrate at the surroundings of Seymour (Marambio) IslandLatitude longitude and depth indicated below correspond to the one at the middle point of each graph

Dep

th(m

bsb

)0

30

50

100

200m

Figure 8 Reflectors recorded with sea-bottom portable profiler(EdgeTech Discover SB-3200-XS) at Bouchard zone (Figure 1) Therandomized distribution of reflectors is shown in the substrate up to110m below seabed (bsb)

0(m)10 20

Figure 9 Images of seabed obtained with side scan sonar in shallowwaters (119888 15m depth) at Bouchard zone (Figure 1) A dense networkof drag marks caused by the heavy traffic of icebergs is shown

Seymour Island low methane concentrations are probablydue to faster gas escapes from sandy sediments which prevailthere This fact contrasts with the highest content of gaseoushydrocarbons in the muddy facies far from the island InWeddell zone (Figures 1 and 4) the relationship betweenhigher contents of gaseous hydrocarbons andmuddy facies isalsomanifested while coarse-grained facies (sand and gravel)are poorer in these gases

According toMienert et al [11] in shallowwatermethaneis transferred to the water column from the sea bottom andmaybe incorporated into the atmosphereThis situation coin-cides with observations done between years 1994 and 2015 in

AA

0(cm)

10

Figure 10 Images of seabed obtainedwith side scan sonar in shallowwaters (119888 8m depth) at Bouchard zone (Figure 1) A round shapes(ldquopockmarksrdquo) associated with fixed leakages of methane

shallow waters at Bouchard zone where numerous gas ventsoccur reaching the atmosphere and being predominantlymethane (c 160000 ppm c 16) and traces of CO

2and H

2S

(Table 2)These gas vents and the presence ofmainlymethanegas in seabed sediments are compatible with the speculationof Macdonald et al [4] about the existence of gas reservoirsin the substrate of the ldquoshallow play zonerdquo of Larsen Basin(James Ross Basin) (see ldquoSection 13 Geological Framerdquo)

Another research directly related to this paper whichsupports the existence of a frozen substrate or al least thepresence of significant amounts of ice was conducted by SilvaBusso et al [12] They detected by geoelectric methods (ie1D and 2D vertical electrical sounding resistive electricaltomography) the presence of criopeg sectors (interbeddedfresh and salty ice) and sectors with relict and discontinuouspermafrost in the coastal and intertidal substrate at the Lopezde Bertodano Bay Seymour Island (Bouchard zone Figure 1)Here the tidal rangewas c 2m reaching c 3mduring tides ofsyzygy Sands and silts with high tomoderate ice content werefound in the substrate up to a depth of cminus85mbsl (maximumrange of the instruments) The maximum ice content wasfound between minus65 and minus85m bsl

The abundant presence of ice within the substrate pro-vides a possible mechanism to explain natural bubblingmethane observed in the area (Figure 1 Bouchard zone)Methane would be contained in underground reservoirs atrelatively shallow depths (c 100ndash300m bsl) which remainstable while the ice box remains frozen being released whencertain conditions vary mainly increase in temperature


0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000

Figure 11 Random distribution of concentrations of CH4(ppm) versus water depth (m) at Bouchard zone is shown (Figure 1) Sample 7 is not

represented on this plot since its maximum positive value of CH4(9995 ppm) is out of scale The average CH

4concentration is 42331 ppm

at a depth of c minus15m

0

minus100

minus200

minus300

minus400

minus500

minus600

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000

Figure 12 Random distribution of concentrations of CH4(ppm) versus water depth (m) atWeddell zone is shown (Figure 1) Sample 20 is not




4 Conclusions

The presence of gaseous hydrocarbons (from C1 to C5) inseabed sediments (Table 1) and the bubbling of methane(Table 2) suggest the presence of gas accumulations in thesubstrate of the marine areas investigated in this study It isin part compatible with the ideas supported by Macdonaldet al [4] who inferred that in this area shallow hydrocarbonreservoirs would contain potentially mainly gas

The release of methane from the frozen ocean substrateadjacent to Seymour Island would be linked to climateinstability during Late Cenozoic when vast areas of theAntarctic continental shelf were flooded during a marinetransgression which occurred c 18000 years ago after theLast Glacial Maximum (LGM) Thus the heat flow fromthe sea to the marine substrate now flooded would havedestabilized frozen gas accumulations which were originallyformed into terrestrial permafrost during the LGM a similarprocess that occurred in the Arctic [13]

Methane vents bubbling from seafloor were observedoff shore some Antarctic islands coasts located at the NWextreme of Weddell Sea (ie Seymour Island) Methaneemanations (bubbles) weremore strong and abundantmainlyduring low tides when gas emanations occurred more fre-quently suggesting that free gas might accumulate in someshallow submarine reservoirs during high tides venting aswater pressure decreases below certain level

Additionally the extraordinary rapid climate warmingwhich is occurring in the northern tip of the Antarctic

Peninsula [14ndash18] would have helped to accelerate the desta-bilization and melting of the frozen gas contained into theshallow marine substrate of the area The consequences ofthis warming can largely be seen in the reduction of landice along West Antarctica and the ice shelves destruction inthe surrounding seas (eg [19 20]) Recent temperatures areextremely high setting a new record of +165∘C in March2015 (Meteorological Station at Esperanza Base ArgentineanAntarctic station) this is an event without precedent duringthe Holocene [14]

Competing Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Authorsrsquo Contributions

(1) Rodolfo Augusto del Valle and E Yermolin contributedto data acquisition information processing and productionof results (2) Jessica Chiarandini and A Sanchez Granelcontributed to the processing of chemical information andproduction of results (3) Jorge Carlos Lusky performed thegeophysical data acquisition

Acknowledgments

Theauthors are grateful to every onewho helpedparticipatedin this paper and especially Dr Umberta Tinivella (OGS-Trieste Italy) who helped to improve the manuscript


References

[1] Lance361 ldquoMethane the other important greenhouse gasrdquo 2015httpslance361wordpresscom20151027methane-the-other-important-greenhouse-gas

[2] D H Elliot ldquoTectonic setting and evolution of the JamesRoss Basin northern Antarctic PeninsulardquoMemoir - GeologicalSociety of America vol 169 pp 541ndash555 1988

[3] R A del Valle D H Elliot and D I M Macdonald ldquoSed-imentary basins on the east flank of the Antarctic Peninsulaproposed nomenclaturerdquo Antarctic Science vol 4 pp 477ndash4781992

[4] D I M Macdonald P F Barker S W Garrett et al ldquoApreliminary assessment of the hydrocarbon potential of theLarsen Basin Antarcticardquo Marine and Petroleum Geology vol5 no 1 pp 34ndash53 1988

[5] P H H Nelson ldquoThe James Ross Island Volcanic Group ofnortheast Graham Landrdquo British Antarctic Survey ScientificReports 54 1966

[6] E Borzotta and D Trombotto ldquoCorrelation between frozenground thickness measured in Antarctica and permafrostthickness estimated on the basis of the heat flow obtainedfrom magnetotelluric soundingsrdquo Cold Regions Science andTechnology vol 40 no 1-2 pp 81ndash96 2004

[7] M Fukuda J Strelin K Shimokawa N Takahashi T Soneand D Tromboto ldquoPermafrost occurrence of Seymour Islandand James Ross Island Antarctic Peninsula Regionrdquo in RecentProgress in Antarctic Earth Science Y Yoshida Ed pp 631ndash636Terra Scientific Publishing Company Tokyo Japan 1992

[8] B J Sloan L A Lawver and J B Anderson ldquoSeismic stratigra-phy of the Larsen Basin eastern Antarctic Peninsulardquo AntarcticResearch Series vol 68 pp 59ndash74 1995

[9] R A Del Valle and H Miller ldquoTranspressional deformationalong the margin of Larsen Basin new data from PedersenNunatak Antarctic Peninsulardquo Antarctic Science vol 13 no 2pp 158ndash166 2001

[10] Synergic Petroleum Technologies SA IPS-Integrated PetroleumSolutions Paraguay

[11] J Mienert J Posewang and M Baumann ldquoGas hydrates alongthe northeastern Atlantic margin possible hydrate-boundmar-gin instabilities and possible release of methanerdquo GeologicalSociety Special Publication vol 137 pp 275ndash291 1998

[12] A Silva Busso Y Yermolin and T Manograsso CzalbowskildquoCaracterısticas del permafrost costero (criopeg) con el uso detecnicas geoelectricas arroyo Dıaz isla Marambio penınsulaAntarticardquoRevista de la Asociacion Geologica Argentina vol 70no 4 pp 583ndash595 2013

[13] C D Ruppel ldquoMethane hydrates and contemporary climatechangerdquo Nature Education Knowledge vol 3 no 10 article 292011

[14] F Fernandoy H Hanno Meyer G Gacitua C Cardenasand U Falk ldquoHigh-resolution climate information from thenorthern Antarctic Peninsula as revealed by shallow firn coresand geophysical datardquo in Proceedings of the 12th InternationalSymposium on Antarctic Earth Sciences (XII ISAES rsquo15) S18Palaeoenvironmental Changes in Antarctica and SouthernOceans since the Last Glacial Maximum Abstract 510 pp 418ndash486 2015

[15] B J Davies J L Carrivick N F Glasser M J Hambrey and JL Smellie ldquoVariable glacier response to atmospheric warmingnorthern Antarctic Peninsula 1988-2009rdquo Cryosphere vol 6no 5 pp 1031ndash1048 2012

[16] N F Glasser T A Scambos J A Bohlander M Truffer E CPettit and B J Davies ldquoFrom ice-shelf tributary to tidewaterglacier continued rapid glacier recession acceleration andthinning of Rohss Glacier following the 1995 collapse of thePrince Gustav Ice Shelf on the Antarctic Peninsulardquo Journal ofGlaciology vol 57 no 203 pp 397ndash406 2011

[17] J Turner S R Colwell G J Marshall et al ldquoAntarctic climatechange during the last 50 yearsrdquo International Journal ofClimatology vol 25 no 3 pp 279ndash294 2005

[18] M R van den Broeke and N P M van Lipzig ldquoChanges inAntarctic temperature wind and precipitation in response tothe Antarctic Oscillationrdquo Annals of Glaciology vol 39 pp 119ndash126 2004

[19] E Rignot ldquoChanges in West Antarctic ice stream dynamicsobserved with ALOS PALSAR datardquo Geophysical ResearchLetters vol 35 no 12 2008

[20] E Rignot J L Bamber M R Van Den Broeke et al ldquoRecentAntarctic ice mass loss from radar interferometry and regionalclimate modellingrdquo Nature Geoscience vol 1 no 2 pp 106ndash1102008

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ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Geological ResearchJournal of


Geology Advances in


Table 1 Summary of analyses of C1 to C5 of sediment samples from the Antarctic seabed

(a) Bouchard zone (Figure 1)

Number of samples88

C1(ppm)

C2(ppm)

C3(ppm)

C4(ppm)

n-C4(ppm)

C5(ppm)

n-C5(ppm)

Maximum 999563 4925 3671 11 64 232 028Minimum 11582 003 481 017 277 007 006Average 42331 2114 1049 4 277 066 0251119877 Maximum = 41 Minimum = 2 Average 119877 = c 232 C1 Maximum = 9989 Minimum = 6344 Average C1 = c 89

(b) Weddell zone (Figure 1)

Number of samples54

C1(ppm)

C2(ppm)

C3(ppm)

C4(ppm)

n-C4(ppm)

C5(ppm)

n-C5(ppm)

Maximum 175387 8665 6406 2275 1928 1406 491Minimum 6527 472 528 170 037 015 003Average 36960 3240 2640 755 649 290 1661119877 Maximum = 24 Minimum = 2 Average 119877 = c 72 C1 Maximum = 9515 Minimum = 70 Average C1 = c 821119877 = C1C2 + C3 2 C1 = C1 lowast 100C1 + C2 + C3 + C4 + C5

Weddell Sea

Snow HillIs

James RossIs

Antarctic Peninsula

JoinvilleIs

DundeeIs

Seymour(Marambio)

Is

Paulet Is

Sampling place Bouchard zoneSampling place Weddell zone

Fossil Bay

Loacutepez deBertodanoBay

58∘W 57

∘W

58∘W

80∘W 70

∘W

70∘W

50∘S

60∘S

64∘S

70∘S

60∘W

60∘W 50

∘W

50∘W

54∘W55

∘W57∘W 56

∘W

minus6426∘S

minus6380∘S

minus6400∘S

minus6420∘S

minus6440∘S

minus6430∘S

minus6435∘S




∘W minus5665∘W





∘W

0 5 10 15 20

(km)

Figure 1 Working areas at the NWWeddell Sea Antarctica Small triangles (red triangle) indicate sampling places at Bouchard andWeddellzones Bouchard zone is enlarged due to the small scale of the map while Weddell zone is in the right scale











2S and CO

2

2 Results









4









2CO2


Sample 25Sample 28

Sample 7

Sample 54

minus6420

minus6425

Latit

ude S

minus6430

minus6435




Samples

100

H

D

80

60

40

20

0

n-C5iso-C5

iso-C4n-C4 C1

C2C3

8681767166615651464136312621161161











Sample 8

Sample 1

Sample 49

Sample 20

minus6380

minus6400

minus6420

minus6440


Latit

ude S



H

D

Samples

100

80

60

40

20

0535047444138353229262319161310741

n-C5i-C5

i-C4n-C4 C1

C2C3





3 Discussion


(b)

(a)

30

50

100

AB

Dep

th(m

bsb

)

64∘12

998400382

998400998400S56

∘38

998400339

998400998400W

110m bsb

64∘13

998400338

998400998400S56

∘31

998400529

998400998400W


Enlarged area






0m bsb


(a)


0m bsb

210 m bsb

A

B

(b)


Dep

th(m

bsb

)0

30

50

100

200m


0(m)10 20




AA

0(cm)

10



2and H

2S





0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





0

minus100

minus200

minus300

minus400

minus500

minus600

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





4 Conclusions






Competing Interests




Acknowledgments



References






























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in











2S and CO

2

2 Results









4









2CO2


Sample 25Sample 28

Sample 7

Sample 54

minus6420

minus6425

Latit

ude S

minus6430

minus6435




Samples

100

H

D

80

60

40

20

0

n-C5iso-C5

iso-C4n-C4 C1

C2C3

8681767166615651464136312621161161











Sample 8

Sample 1

Sample 49

Sample 20

minus6380

minus6400

minus6420

minus6440


Latit

ude S



H

D

Samples

100

80

60

40

20

0535047444138353229262319161310741

n-C5i-C5

i-C4n-C4 C1

C2C3





3 Discussion


(b)

(a)

30

50

100

AB

Dep

th(m

bsb

)

64∘12

998400382

998400998400S56

∘38

998400339

998400998400W

110m bsb

64∘13

998400338

998400998400S56

∘31

998400529

998400998400W


Enlarged area






0m bsb


(a)


0m bsb

210 m bsb

A

B

(b)


Dep

th(m

bsb

)0

30

50

100

200m


0(m)10 20




AA

0(cm)

10



2and H

2S





0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





0

minus100

minus200

minus300

minus400

minus500

minus600

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





4 Conclusions






Competing Interests




Acknowledgments



References






























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in




2CO2


Sample 25Sample 28

Sample 7

Sample 54

minus6420

minus6425

Latit

ude S

minus6430

minus6435




Samples

100

H

D

80

60

40

20

0

n-C5iso-C5

iso-C4n-C4 C1

C2C3

8681767166615651464136312621161161











Sample 8

Sample 1

Sample 49

Sample 20

minus6380

minus6400

minus6420

minus6440


Latit

ude S



H

D

Samples

100

80

60

40

20

0535047444138353229262319161310741

n-C5i-C5

i-C4n-C4 C1

C2C3





3 Discussion


(b)

(a)

30

50

100

AB

Dep

th(m

bsb

)

64∘12

998400382

998400998400S56

∘38

998400339

998400998400W

110m bsb

64∘13

998400338

998400998400S56

∘31

998400529

998400998400W


Enlarged area






0m bsb


(a)


0m bsb

210 m bsb

A

B

(b)


Dep

th(m

bsb

)0

30

50

100

200m


0(m)10 20




AA

0(cm)

10



2and H

2S





0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





0

minus100

minus200

minus300

minus400

minus500

minus600

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





4 Conclusions






Competing Interests




Acknowledgments



References






























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


Sample 8

Sample 1

Sample 49

Sample 20

minus6380

minus6400

minus6420

minus6440


Latit

ude S



H

D

Samples

100

80

60

40

20

0535047444138353229262319161310741

n-C5i-C5

i-C4n-C4 C1

C2C3





3 Discussion


(b)

(a)

30

50

100

AB

Dep

th(m

bsb

)

64∘12

998400382

998400998400S56

∘38

998400339

998400998400W

110m bsb

64∘13

998400338

998400998400S56

∘31

998400529

998400998400W


Enlarged area






0m bsb


(a)


0m bsb

210 m bsb

A

B

(b)


Dep

th(m

bsb

)0

30

50

100

200m


0(m)10 20




AA

0(cm)

10



2and H

2S





0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





0

minus100

minus200

minus300

minus400

minus500

minus600

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





4 Conclusions






Competing Interests




Acknowledgments



References






























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


0m bsb


(a)


0m bsb

210 m bsb

A

B

(b)


Dep

th(m

bsb

)0

30

50

100

200m


0(m)10 20




AA

0(cm)

10



2and H

2S





0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





0

minus100

minus200

minus300

minus400

minus500

minus600

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





4 Conclusions






Competing Interests




Acknowledgments



References






























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





0

minus100

minus200

minus300

minus400

minus500

minus600

Dep

th (m

)

CH4 (ppm)

180016001400120010008006004002000





4 Conclusions






Competing Interests




Acknowledgments



References






























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


References






























Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in










Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in

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