'Fried Egg' may be impact crater in the Azores

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'Fried Egg' may be impact crater
By Jonathan Amos
Science correspondent, BBC News, San Francisco




Fried Egg: Vertical exageration factor is 2 (EMEPC)
The Egg (l) and its companion obtained by multibeam echosounder bathymetry

Portuguese scientists have found a depression on the Atlantic Ocean floor they think may be an impact crater.

The roughly circular, 6km-wide hollow has a broad central dome and has been dubbed the "Fried Egg" because of its distinctive shape.

It was detected to the south of the Azores Islands during a survey to map the continental shelf.

If the Fried Egg was made by a space impactor, the collision probably took place within the past 17 million years.

This is the likely maximum age of the basaltic sea-floor rock which harbours the feature.

"To be sure, we need to take samples and make a profile of the sediment layers to determine if there really is a central uplift from an impact," explained Dr Frederico Dias from EMEPC (Task Group for the Extension of the Portuguese Continental Shelf).

"We need also to see all the signatures that are consistent with a high velocity impact, like glasses from melting and, of course, debris; and what are called shatter cones (shocked rocks)," he told BBC News.

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Central peaks

Dr Dias described the putative impact feature here at the American Geophysical Union's (AGU) Fall Meeting, the world's largest annual gathering of Earth scientists.

The Fried Egg was first identified in data gathered by a 2008 multibeam echosounder hydrographic survey. A further cruise from September to November this year confirmed its presence.

It lies under 2km of water about 150km from the Azores archipelago.

The depressed ring sits roughly 110m below the surrounding ocean bottom, with the circular dome-shaped central uplift 3km in diameter and with a base-to-top height of some 300m.

Central peaks are often associated with meteorite impacts and form when the compressed crater floor rebounds. A peak is not definitive proof of an impact, however.

A volcanic origin for the Fried Egg seems unlikely because the Portuguese team has not been able to find any lava flows within the structure or on its surroundings.

Second crater

Interestingly, there is another - but much smaller - feature just 3-4km to the west of the egg.

"It's just by the side. If the Fried Egg is a crater, this could be a crater also," speculated Dr Dias.

Dr Dias and colleagues are examining gravity and magnetic data gathered during September's cruise. A third expedition to the area early next year will use a remotely operated vehicle (ROV) to try to retrieve samples from the ocean floor for analysis.

The Portuguese team detailed the currently available Fried Egg data on a poster at the AGU meeting. Other researchers who came to view the information were split on the impact theory, Dr Dias said.

"Even if it's not an impact crater it's still a very interesting feature," he told the BBC.

The EMEPC is working under the United Nations Convention on the Law of the Sea to establish the true extent of Portuguese territorial waters.

Jonathan.Amos-INTERNET@bbc.co.uk

http://news.bbc.co.uk/2/hi/science/nature/8400264.stm

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"Fried Egg" in the bottom of Atlantic Ocean



By ruiandrade14

It looks with a fried egg so much that the person who discovered it first, couldn't think of any other suitable name for this geologic formation

Located at the bottom of the Northern Atlantic Ocean, 150 kilometers from the Azores islands, near Portugal, this "Egg" left the Portuguese scientists amazed enough to be divulged at the annual meeting of the A.G.U. (American Geophysical Union). This discovery was made last year during a scientific expedition by E.M.E.P.C. (Task Group for the Extension of the Continental Shelf), while trying to revindicate that the portuguese continental platform it's beyond the 200 nautical miles, giving the right to the country of exploring the marine resources deep below, using sound probes to map the morphology of the bottom of the ocean.

With that data, high resolution maps were made of the ocean floor to be delivered to the U.N. with the proposal of the extension of the continental shelf. However, it was only after that the investigators looked at the maps with other scientific purposes and discovered the "Fried Egg", around 2000 meters beneath the surface.

Imagery has revealed a circular structure with 6 km in diameter, and at the center there was an "bump" with 3 km diameter, the "white part of the egg" it's 100 meter deeper than the surrounding area and from the base of the "white" to the top of the "yolk" it's 300 meters.

Last October, the E.M.E.P.C. team returned to the site to confirm the discovery and to dive the portuguese marine robot "Luso" ,if the weather conditions allowed. However, the dive was not possible and it was postponed until 2010, and hopefully the robot will collect rock and sediments samples for further study of this "Egg".

In the meantime, some hypothesis were already made on the origin of this strange structure, the engineer hydrographer oceanographer physicist Manuel Abreu, E.M.E.P.C. scientist in charge, states that it could be a crater made by a meteorite impact, a mud volcano, or something completely different and unknown.

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The meteorite hypothesis



 The structure presents some resemblances with a collision between a cosmic body and the surface of the Earth, it's common to have a elevation at the center of a impact crater caused by a meteorite. If the presence of glass is found in the crater, that would prove a meteorite impact with no more than 17 million years old, because that's the age attributed to that particular bottom ocean area. The amount of sediments at the top of the "yolk" could also be a hint on the actual age of the structure. At the moment, the E.M.E.P.C. team it's running simulations to determine the dimensions of the object to cause such a crater, if that was what happened.

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The mud volcano hypothesis

 There is another explanation for this structure, a formation created by geo-excreted liquids and gases, known as a mud volcano. The problem it's that all mud volcanoes known at this time haven't formed in areas with the same geological context as this "Fried Egg" is found, because the sediments layer is not thick enough to hold the fluids coming from the inside of Earth, like the case of the methane gas from the mud volcanoes, and there is not known any compression between tectonic plates in that area. The mud volcanoes have an economic interest, because it's a known alternative energy source, and if it is indeed one, it would represent a new class of this geological formations.

And to furthermore amaze the scientists, another strange and similar geological formation was found about 3 to 4 km from the "Fried Egg", shown at the right side of the above picture. The presentation of the discovery at the A.G.U. has opened the debate for the worldwide scientific community, with opinions dividing between the mud volcano and the meteorite crater theories.

Related links

    * Meteor Crater - Wikipedia, the free encyclopedia
    * Mud volcano - Wikipedia, the free encyclopedia
    * http://www.emepc.pt

http://hubpages.com/hub/Fried-Egg-in-the-bottom-of-Atlantic-Ocean

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http://www.youtube.com/watch?v=zH-z6Y7rhBY&feature=player_embedded

The crater lakes of Flores Island (Azores)

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The Fried Egg is a provisional name for a suspected impact crater. It is 2 km underwater about 150 km away and to the south from the Azores. It was identified in 2008 by sonar soundings. It is probably less than 17 million years old.

It has a depressed ring which is roughly 110m below the surrounding ocean bottom, and a circular dome-shaped central uplift 3km in diameter and with a base-to-top height of some 300m.