1Department of Geosciences at the University of Bremen, Klagenfurter
Str., 28359 Bremen, Germany
2MARUM Center for Marine Environmental Sciences, Leobener Str., 28359
Bremen, Germany
3Max-Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359
Bremen, Germany
4Universidad Nacional Autónoma de México, Instituto de Ciencias
del Mar y Limnología, A. P. 70-305 Ciudad Universitaria, 04510 Mexico
City, México
5Florida State University, P.O. Box 3064326, Tallahassee, FL 32306, USA
6Alfred Wegener Institute Helmholz Centre for Polar and Marine
Research, HGF-MPG Group for Deep Sea Ecology and Technology, Am Handelshafen
12, 27570 Bremerhaven, Germany
7Center for Earth Sciences, University of Vienna, Althanstr. 14, 1090
Vienna, Austria
1Department of Geosciences at the University of Bremen, Klagenfurter
Str., 28359 Bremen, Germany
2MARUM Center for Marine Environmental Sciences, Leobener Str., 28359
Bremen, Germany
3Max-Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359
Bremen, Germany
4Universidad Nacional Autónoma de México, Instituto de Ciencias
del Mar y Limnología, A. P. 70-305 Ciudad Universitaria, 04510 Mexico
City, México
5Florida State University, P.O. Box 3064326, Tallahassee, FL 32306, USA
6Alfred Wegener Institute Helmholz Centre for Polar and Marine
Research, HGF-MPG Group for Deep Sea Ecology and Technology, Am Handelshafen
12, 27570 Bremerhaven, Germany
7Center for Earth Sciences, University of Vienna, Althanstr. 14, 1090
Vienna, Austria
Received: 17 Mar 2016 – Discussion started: 24 Mar 2016 – Revised: 29 Jun 2016 – Accepted: 19 Jul 2016 – Published: 11 Aug 2016
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.
We were excited about nature’s diversity when we discovered spectacular flows of heavy oil at the seafloor with the remotely operated vehicle QUEST 4000 m in Campeche Bay, southern Gulf of Mexico. Vigorous methane gas bubble emissions lead to massive gas hydrate deposits at water depth as deep as 3420 m. The hydrates formed metre-sized mounds at the seafloor that were densely overgrown by vestimentiferan tubeworms and other seep-typical organisms.
We were excited about nature’s diversity when we discovered spectacular flows of heavy oil at...
