19/10/2017 Exploring the canyons in Lofoten

 

The Lofoten islands are visited by millions of people each year. We made a different kind of journey to the famous archipelago, looking not for mountains and beaches. But for the stuff of life itself. And some crusts.

Text: Maja Sojtaric

Lofoten is famous for many things: the scenery that inspired the creators of Disney´s Frozen; the stock fish hanging as curtains on racks all along its coast; the campers that line its narrow roads and pristine beaches all summer long; its fisheries and the local resistance against petroleum industry looking for oil in its fish rich waters. What the islands are not famous for, are their canyons.

And that is not surprising: we can’t see them, as they are hidden by the ocean waters at 750m water depth. I imagine the ocean floor as flat and boring. But the continental margin off Lofoten archipelago has actually the most varied topography in Norway. And that´s something, in the country famous for deep fiords and craggy mountains.

Scientists and pilots in front of the ROV Ægir

Scientists and pilots in front of the ROV Ægir
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Norway’s scientific remotely operated vehicle (ROV) has been christened Ægir, after the old Norse god of the sea. It has been operational since 2015, an important addition for Norway´s scientific community. Pictured with scientists and operators on board RV G.O. Sars. Photo: Maja Sojtaric


 

It is actually somewhat of a mystery as to why many of the canyons along the continental margin offshore Lofoten and neighbouring Vesterålen were formed in the first place.  But methane-rich fluids migrating through the sediment and seeping through the ocean floor may have played an important role.

So, the scientists from CAGE and our partner Geological Survey of Norway boarded the Norwegian research vessel, RV G.O. Sars, in order to closely explore two of the smaller of the several canyons that have been found in this region. And I went along for a ride.

The journey was a part of the NORCRUST project. Read more about it:  Norwegian Research Council – Petromaks 2

The untapped potential of the nameless canyons

A while back marine geologist Jochen Knies saw two blurry images in a scientific presentation that got his imaginative juices going. Those images are the reason why we were found sitting aboard Research Vessel G.O. Sars on our way to the outer rim of the vast Norwegian shelf, listening to Knies enthusiastically speculating on what we may see.

“Norwegian ocean mapping programme MAREANO  has recorded one video line crossing the canyon area, that gives us some hints as to what we may find. But it leaves a lot of room for speculation – if your imagination is vivid enough. Luckily we have tools on this ship to see if any of our ideas hold up.”

Knies is alluding to the remote operating vehicle (ROV) Ægir6000:  a human-controlled robot that enables scientists to meticulously record the ocean floor in high definition images and video, picking up samples as they do so.

ROV Æegir 600

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Ægir 6000 is tailor made for Norwegian research vessels, but can also be used on other vessels. It is connected to the mother ship with a steel cable, several kilometers long, which supplies it with power and sends images and data to the surface. Using its robotic arms, the pilots of the ROV can pick up samples from the deep ocean floor. Ægir can withstand gale force winds. Photo: Maja Sojtaric


 

The nameless Lofoten canyons are a frontier area to be explored, Knies tells me:  since we don’t know anything about them, by the end of the weeklong expedition we will know a little bit more.

Life in fluorescent silvery blue

The blurry features on the images Knies showed on the first afternoon of the expedition, might have made the blood rush for the room full of the young scientists that joined this cruise. They definitely saw what I, and surely most other people, are not able to see.

The images were of low resolution, and showed a greenish, grey sea, muddy seabed, and occasional lumpy mounds alongside what appeared to be mats of silvery blue mucus on the sea floor.

“Microbial mats! “the excited hum went through the meeting room next to the operation centre for the ROV.

Arunima Sen, postdoc biology

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“We have images and video of the ocean floor from other cruises, but they have not been acquired with a biological perspective in mind. My job is to create mosaics from images and videos that are done correctly so that a biologist can use them. In the Arctic and North Atlantic the communities around cold methane seeps are not much studied. But we do see that they are different from other cold seeps in lower latitudes. The point of having spatially explicit pictures is to get the numbers of the different species and individuals so that we can properly compare different sites to each other. That’s why knowing the spatial extent of the mosaics is important. “ Photo: Maja Sojtaric


 

It turns out the fluorescent silvery blue film on the sea bed is more exciting then I gave it credit for: It could actually be the equivalent of the original stuff of life itself.

These mats are colonies of microbes that live in the interface between methane and sulphide rich sediment and oxygenated waters. As opposed to many organisms on our planet, they do not depend on light – photosynthesis –  to gain energy and produce biomass. 

All they need in the deep darkness of the ocean is a carbon source, such as methane, seeping from below to thrive. And provide sustenance for marginally more complex life forms such as single celled foraminifera and tube worms. 

Some scientists have earlier speculated that such microbial colonies, may be the way life on Earth began

But by themselves the microbes do not necessarily tell the full story of the methane seeps. It helps if you find some crusts.

Looking for some old crusts

Carbonate crusts are the geologic by-product of the microbe’s life at the seeps. 

These kind of crusts form only in shallow sediments in places where methane arises to the seafloor. They can appear as the lumpy mounds in otherwise bland surroundings, such as the ones we saw in those blurry photos.

 

Tobias Himmler, postdoc geology

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"My main objective is to describe lithology – the general physical characteristics - of the carbonates that scientists collect. Lithology can change depending on the intensity of methane flux. Based on the texture of the rock you can reconstruct the energy and intensity of the flux." says Himmler. Photo: Maja Sojtaric


 

“It’s like opening up the birth certificate of a methane seep. Carbonate crusts serve as archives of past emissions at the seep. And by studying individual layers within carbonate crusts closely, we can find out when past methane seeping episodes have occurred and what were the triggering mechanisms. It is all written in the crust, and it is our task to decipher this story.” says researcher Aivo Lepland.

It may take 300 to 500 years to grow a mere centimetre of carbonate crust. So, there is a lot of “time” recorded by carbonate crusts that may be up to 30 cm thick.

Wei Li Hong, postdoc geochemistry

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“Carbonates don’t grow from a solid. They grow – are precipitated - from the water that contains significant amounts of bicarbonate. To transform methane to bicarbonate you need a microbial process. The microbes are depending on water to live. This microbial process needs water. If you want to know the fundamentals of development of methane-derived carbonate, you need to know what is happening in the water""


The weakness

Here is the kicker, that really drives the importance of the imaginative, cross disciplinary approach to research home for me. Within a week of exploration these extremely specific disciplines pulled their resources together to come up with a viable idea on how these canyons might have been created.

Pierre Antoine Dessandier, postdoc micropaleontology

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"I am examining the micro fossils that are deposited in the sediments surrounding methane seeps. “We are interested to measure the amount of living foraminifera and isotopes of living foraminifera in this environment. Foraminifera are single celled organisms that live in the ocean or on the ocean floor. They have tests that can be found in the sediments, and that can tell us a lot about the environments that they were created in.” says Dessandier. Photo: Maja Sojtaric


 

“Microbial mats, carbonate crusts, microfossils and fauna are features in these canyons that indicate that there is active fluid flow beneath them. This means that there may be movement of liquids and gases including methane underneath the ocean floor.  Which may very well be one of the reasons the canyons were formed in the first place.” says Knies

In short: methane release from the ocean floor may have caused a weakness in the sediments that contributed to development of these huge dents in the Norwegian continental margin. 

Scientists suggest a process that is absolutely invisible for me, and to which individual scientific disciplines alone offer only a partially obstructed view.

“This is such an exciting site” says Lepland “It is unusual that a site like this has not been investigated before. There are clearly some underlying geological reasons why there is methane leakage inside these canyons. We are trying to apply new methods and are joined by young scientists from many different disciplines who help us squeeze more information out of the samples we collect. Today we have new tools to look into this that we didn’t have just a few years back.”

 


 

Fact box: NORCRUST (LINK)

NORCRUST – Norwegian margin fluid systems and methane derived carbonate crusts” is a collaborative project lead by the Geological Survey of Norway (NGU), funded by The Research Council of Norway’s (NFR),  PETROMAKS 2 programme.

Partners are “CAGE – Center for Arctic Gas Hydrate, Environment, and Climate” at the University of Tromsø, Migris AS , Statoil ASA, Lundin Norway AS, and ENI Norge.

NORCRUST aims to study natural methane seepage sites at the seabed of the Norwegian-Barents seas by integrating geological, geochemical, and biological data. NORCRUST wants to understand the dynamics and history of these fluid flow systems and its control factors.

This requires knowledge of timing of hydrocarbon migration to the seafloor, ability to distinguish hydrocarbon origin from shallow biogenic and deep thermogenic sources, and reliable assessment of the temperature and depth of hydrocarbon formation.

NORCRUST will provide this knowledge by applying recent technological and scientific advances on methane-derived carbonate crusts formed at seepage sites and gas-impregnated sediments during active leakage of hydrocarbons. We have been using remotely operating vehicles (ROV) to inspect the seafloor and sample carbonate crusts, gas bubbles released from the seafloor and surrounding sediments.

 

 

 

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