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Sahling, Heiko; Borowski, Christian; Escobar-Briones, Elva; Gaytán-Caballero, Adriana; Hsu, Chieh-Wei; Loher, Markus; MacDonald, Ian R; Marcon, Yann; Pape, Thomas; Römer, Miriam; Rubin-Blum, Maxim; Schubotz, Florence; Smrzka, Daniel; Wegener, Gunter; Bohrmann, Gerhard (2016): (Supplementary Table 1) Proportions of methane (C1) to ethane (C2) and the stable isotope composition of methane (δ¹³CCH4) of gas and oil collected by gas bubble sampler during METEOR cruise M114/2 in the southern Gulf of Mexico. PANGAEA, https://doi.org/10.1594/PANGAEA.860373, Supplement to: Sahling, H et al. (2016): Massive asphalt deposits, oil seepage, and gas venting support abundant chemosynthetic communities at the Campeche Knolls, southern Gulf of Mexico. Biogeosciences, 13(15), 4491-4512, https://doi.org/10.5194/bg-13-4491-2016

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Abstract:
Hydrocarbon seepage is a widespread process at the continental margins of the Gulf of Mexico. We used a multidisciplinary approach, including multibeam mapping and visual seafloor observations with different underwater vehicles to study the extent and character of complex hydrocarbon seepage in the Bay of Campeche, southern Gulf of Mexico. Our observations showed that seafloor asphalt deposits previously only known from the Chapopote Knoll also occur at numerous other knolls and ridges in water depths from 1230 to 3150 m. In particular the deeper sites (Chapopopte and Mictlan knolls) were characterized by asphalt deposits accompanied by extrusion of liquid oil in form of whips or sheets, and in some places (Tsanyao Yang, Mictlan, and Chapopote knolls) by gas emission and the presence of gas hydrates in addition. Molecular and stable carbon isotopic compositions of gaseous hydrocarbons suggest their primarily thermogenic origin. Relatively fresh asphalt structures were settled by chemosynthetic communities including bacterial mats and vestimentiferan tube worms, whereas older flows appeared largely inert and devoid of corals and anemones at the deep sites. The gas hydrates at Tsanyao Yang and Mictlan Knolls were covered by a 5-to-10 cm-thick reaction zone composed of authigenic carbonates, detritus, and microbial mats, and were densely colonized by 1-2 m-long tube worms, bivalves, snails, and shrimps. This study increased knowledge on the occurrences and dimensions of asphalt fields and associated gas hydrates at the Campeche Knolls. The extent of all discovered seepage structure areas indicates that emission of complex hydrocarbons is a widespread, thus important feature of the southern Gulf of Mexico.
Further details:
Sahling, G; Bohrmann, Gerhard (2016): Seafloor images along 14 ROV profiles during METEOR cruise M114/2. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.863824
Sahling, Heiko; Bohrmann, Gerhard (2016): Navigation tracks of METEOR cruises M114/1 and M114/2. PANGAEA, https://doi.org/10.1594/PANGAEA.864043
Coverage:
Median Latitude: 21.900830 * Median Longitude: -93.442204 * South-bound Latitude: 19.930550 * West-bound Longitude: -94.342733 * North-bound Latitude: 22.393467 * East-bound Longitude: -93.246133
Date/Time Start: 2015-03-05T19:32:00 * Date/Time End: 2015-03-18T19:11:00
Minimum Elevation: -3370.0 m * Maximum Elevation: -1287.0 m
Event(s):
GeoB19318-9 (M114/2_75-9) * Latitude: 19.930550 * Longitude: -94.342733 * Date/Time: 2015-03-05T19:32:00 * Elevation: -1287.0 m * Location: Gulf of Mexico * Campaign: M114/2 * Basis: Meteor (1986) * Method/Device: Gas bubble sampler (GBS) * Comment: GBS-1 (yellow), bubble stream in pockmark
GeoB19325-13 (M114/2_82-13) * Latitude: 21.900000 * Longitude: -93.435217 * Date/Time: 2015-03-11T01:10:00 * Elevation: -2925.0 m * Location: Gulf of Mexico * Campaign: M114/2 * Basis: Meteor (1986) * Method/Device: Gas bubble sampler (GBS) * Comment: GBS-1 (yellow), gas stream of VTLC
GeoB19336-15 (M114/2_93-15) * Latitude: 22.024833 * Longitude: -93.246217 * Date/Time: 2015-03-15T00:40:00 * Elevation: -3082.0 m * Location: Gulf of Mexico * Campaign: M114/2 * Basis: Meteor (1986) * Method/Device: Gas bubble sampler (GBS) * Comment: GBS-2 (blue) with gas, altitude 5.4 - 8 m
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1Event labelEventSahling, Heiko
2Latitude of eventLatitudeSahling, Heiko
3Longitude of eventLongitudeSahling, Heiko
4Elevation of eventElevationmSahling, Heiko
5Area/localityAreaSahling, Heiko
6SiteSiteSahling, Heiko
7Sample code/labelSample labelSahling, Heikodive
8Methane/ethane ratioC1/C2Sahling, Heiko
9δ13C, methaneδ13C CH4‰ PDBSahling, Heikowith respect to VPDB
10CommentCommentSahling, Heiko
Size:
48 data points

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