Scientists examine mysterious tar mounds in the West African deep ocean

November 9, 2014
Blobfish around an asphalt mound. Credit: National Oceanography Centre, Southampton

More than two thousand mounds of asphalt harbouring a wealth of deep-water creatures have been discovered up to two kilometres deep, off the coast of Angola. In a study published in the journal Deep-Sea Research 1, scientists at the National Oceanography Centre (NOC) have been examining the images and data captured at the site to build an intriguing picture of the life and geology of this underwater area.

The naturally-occurring asphalt mounds are made up of the same substance that covers our roads. They range in size from single football-sized blobs to small hills several hundred metres across. It is the first time that these seabed asphalt mounds have been found on this side of the Atlantic – until now these features had only been seen in the Gulf of Mexico and off the coast of California. These deep-sea 'slow tar volcanoes' are associated with flows of from within the sediment and are formed from hydrocarbons migrating around subsurface salt structures.

Researchers have also discovered that the vast array of mounds is home to at least 21 types of deep-water creatures, including large sponges, soft-corals, octopus and fish. Many more common deep-water animals, such as the blobfish and also live near the mounds. This is a greater number of species than had previously been thought and important information for scientists when predicting biodiversity levels in similar areas of ocean.

Octopus on an asphalt mound. Credit: National Oceanography Centre, Southampton

The distinct mounds of asphalt were discovered by the oil company BP, who were carrying out exploration for oil reserves off Angola. Their initial surveys of the seafloor of these areas of huge oil reserves revealed some unusual surface features, which were subsequently investigated using underwater robots. In the area of seabed investigated, which was around the size of the Isle of Wight, a total of 2254 mounds were identified by side-scan sonar, covering a total area of 3.7 square kilometres of seafloor, about the area of a small town.

BP technical experts subsequently sent the deep-sea images to scientists in Southampton as part of a long-running collaboration between the oil industry and marine scientists at NOC.

Lead author of the study, Daniel Jones from NOC, said: "This exciting discovery was a great example of collaboration between oil companies and marine scientists. By working together as a team, we used the industrial data and expertise to get a much better understanding of these important systems, which will be of great value both to the scientists, but also to the BP environmental management teams."

Seafan mound. Credit: National Oceanography Centre, Southampton

The scientific study entitled Asphalt mounds and associated biota on the Angolan margin was jointly authored by NOC, BP and their subcontractor, Fugro. The data for the paper were provided by BP Exploration (Angola) Limited as the operator of block 31 and associated partners.

It is the first time that asphalt mounds have been studied in such detail and the study's findings will help with future predictions of seabed patterns, rock types and habitat in similar areas of ocean.

Explore further: Scientists discover new coral species off California

More information: Asphalt mounds and associated biota on the Angolan margin, Daniel O.B. Jones, Anne Walls, Michael Clare, Mike S. Fiske, Richard J. Weiland, Robert O'Brien, Daniel F. Touzel,Deep Sea Research Part I: Oceanographic Research Papers, Volume 94, December 2014, Pages 124–136, DOI: 10.1016/j.dsr.2014.08.010

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18 comments

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BSD
4.8 / 5 (11) Nov 09, 2014
"Great, now let's get in and fuck the place up."

- BP
ryggesogn2
2.3 / 5 (16) Nov 09, 2014
Asphalt support life.
Nature leaks more oil than humans.
Shootist
2.1 / 5 (16) Nov 09, 2014
Nature leaks orders of magnitude more petroleum, methane, CO2 and natural gas, than humans do.
Scottingham
5 / 5 (10) Nov 09, 2014
This exciting discovery was a great example of collaboration between oil companies and marine scientists.

Don't hear that too often...

Also, there might be more natural seepage than, say, the Deepwater Horizon event, but the RATE of seepage is what is damaging.
big-ben-not-the-bell
3 / 5 (2) Nov 09, 2014
"It is the first time that these seabed asphalt mounds have been found on this side of the Atlantic – until now these features had only been seen in the Gulf of Mexico and off the coast of California."
I don't recall exactly where they were found, but I believe it could have been the Sea of Galilee. For the past two thousand years, the local inhabitants have been harvesting asphalt, as the pillows of various sizes float to the surface.
big-ben-not-the-bell
5 / 5 (4) Nov 09, 2014
Correction, The Dead Sea, not the Sea of Galilee.
"Large blocks of mineral matter free (less than 0.1%) asphalt are occasionally found floating on the surface of the Dead Sea. Chemical, spectroscopic and isotopic data are given for the asphalt. The source of the asphalt is not accurately known, but presumably it represents mobilization of heavy viscous asphaltic masses at depth below the lake bottom into the floor of the lake. It may be released to the surface by earth tremors."
gkam
4.1 / 5 (9) Nov 09, 2014
The History Channel will tell us they are the remains of underwater roads for Ancient Aliens.
nkalanaga
5 / 5 (4) Nov 09, 2014
gkam: More likely the city streets of Atlantis...
Torbjorn_Larsson_OM
5 / 5 (10) Nov 09, 2014
"there might be more natural seepage than, say, the Deepwater Horizon event, but the RATE of seepage is what is damaging."

And in cases like climate change, it is the addition to the natural background of greenhouse gases that does the damage.
barakn
4.9 / 5 (14) Nov 09, 2014
Annual natural seepage distributed throughout the entire Gulf is estimated at 70,000 tonnes/year whereas the BP oil spill released 700,000 tonnes, most during a period of 87 days, i.e. 40x the annual rate. Each of these low-volume natural seeps has its own unique chemical signature and unique set of bacteria adapted to that seep, so the bacteria are already working on breaking it down at the point of release, vs. the BP disaster which released an immense amount of oil from a virgin location.
pandora4real
5 / 5 (6) Nov 09, 2014
Also, there might be more natural seepage than, say, the Deepwater Horizon event, but the RATE of seepage is what is damaging.


Trolls seem to have a real cognitive block with things like rate and geologic time scales. Their imagination seems to be limited to what doesn't exist.
rocket77777
1 / 5 (5) Nov 09, 2014
On land, you see weeds/bugs grow on cracks....so no big deal.
TechnoCreed
5 / 5 (4) Nov 09, 2014
Nature leaks orders of magnitude more petroleum, methane, CO2 and natural gas, than humans do.
Yeah nature is a bitch isn't she? she is even out to get our moneh what a slut.
Slick
2 / 5 (4) Nov 10, 2014
from the post:
'discovered by the oil company BP, who were carrying out exploration for oil reserves off Angola. Their initial surveys of the seafloor of these areas of huge oil reserves...'

These 'huge oil reserves' must never be brought to market. BP knows this, it will be amazing the money and corruption that will flow to get this oil to market. Fook We the People, or fook BP, as we're installing renewable energy, take your pick.
antigoracle
1.7 / 5 (6) Nov 10, 2014
To all the oil and coal haters, can you tell us what source of power you use, so that we may join your esteemed club. Thanks.
Tektrix
4.3 / 5 (6) Nov 10, 2014
"To all the oil and coal haters, can you tell us what source of power you use, so that we may join your esteemed club. Thanks."

I use freshly squeezed troll-juice. There's a nearly unlimited supply, thanks to folks like y'all. ;)
antigoracle
1 / 5 (3) Nov 11, 2014
I use freshly squeezed troll-juice...blah..blah...blah

It's a pity you don't drink it, you might just grow a brain.
dtxx
5 / 5 (2) Nov 11, 2014
Nature leaks orders of magnitude more petroleum, methane, CO2 and natural gas, than humans do.
Yeah nature is a bitch isn't she? she is even out to get our moneh what a slut.


Damn, we're the ones with the mines, and you're calling her the gold digger?

I'll avoid commenting on power sources, but as for British Petroleum... it seems Her Majesty has found a new way to keep The Empire alive. And they don't call them colonies anymore, but instead they are business partners. The Angolan oil must be harvested, you see, "For God and Empire." As someone who doesn't particularly care for the british government, and even less so for SkyKing 9000, I find such reasoning a totally useless platitude when they are trying to justify their shitty, still-exploiting-the-natives type behavior.

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