This summer a joint team of structural geologists and sedimentologists from UiB and UiT The Arctic University of Norway journeyed across the North Atlantic to visit Wollaston Forland in the northern part of East Greenland. The reason? To investigate an exhumed rift basin, and detail its basin-bounding border fault system, the associated deep-marine basin fill strata, and the diagenetic history of the basin.  

Sten-Andreas Grundvåg (UiT), with contributions from Dr. Eric Salomon, Dr. Gijs Henstra, Dr. Thomas Berg Kristensen, and Prof. Atle Rotevatn (all UiB)

Greenland. Close your eyes and think of it for a moment. Anticipation. Breathe in the cold Arctic air and listen to the howling wind as it whispers into your ears. The call of the wild. To most people Greenland is associated with glaciers and icebergs, deep fiords, muskox and polar bears. For a good reason. The majority of Greenland is covered all-year-round by a vast ice shield, up to several thousand meters thick, and the island hosts the World’s largest national park. However, most of the coastlines are practically devoid of ice and snow during the two-three months of Arctic summer. To geologists, the short and intense Arctic summer is a blessing. That is at least how it should be in theory.

Looking out the window from our Twin Otter propeller plane revealed a different story. Despite being early August, the past weeks of heat in Europe had translated to a cold summer in East Greenland: sea ice still covered the fiords, and many mountains and valleys were peacefully hiding under a white coat. ‘Will we be able to land in Lindeman Fiord?’ Just one of the many questions I asked to myself while looking out the window in despair. Since we had left Reykjavik in Iceland some days earlier, we had been stuck at the airstrip at Constable Point (CNP) waiting on better flight conditions up north. Ironically, the sun was shining at CNP, transforming the runway in to a dusty desert-like habitat full of thriving mosquitos. What a great feeling to finally be on our way. Northbound. To our surprise and great luck, the amount of snow and the extent of the sea ice cover far below us, slowly diminished as the small aircraft proceeded northward. Of less fortune was the increasing amount of fog protruding from the ocean into the narrow fiords. Thus, instead of Lindeman Fiord, the pilots chose a much safer alternative and left us at the Danish research station in Zackenberg, 20–30 km south of our planned final destination. More waiting and waste of valuable field days ahead. Despite the Danes treating us friendly and feeding us superb supper every night, we struggled to settle in. One day we found some pieces of outcrop some 10 swampy kilometers north of the station. The effect of the discovery was just as our commander (read. Prof. Rotevatn) had hoped. After nearly a week on hold, the team was on the edge, but eventually doing something intellectually satisfying together increased the moral. Not only did the crumbly rocks strengthen our desire to get to Lindeman Fiord, but it also extinguished a rising mutiny (with four team members planning an escape from Zackenberg with a pulkka mounted on a sea-ice raft). The next day we got what we hoped for: sun, no fog, and a Twin Otter with the finest Icelandic pilots there is. After one quick flyby and some hardcore action movie-style landing maneuvers, we were safely on the ground on the “runway” in Lindeman Fiord, Wollaston Forland. To call this 100 m long and 40 m wide gravel terrace a runway is an exaggeration at best (all honor to the skilled and brave pilots). Nonetheless, this terrace would serve as our home the next week or so. Establishing a basecamp for five persons always takes some time. First tents, then a lavvo, all secured with rocks, and finally a trip wire fence armed with pyro to alert us in case of visitors in the shape of white fury beasts. For some reasons unknown, the fence tended to attract more professors than polar bears.

What is great about doing fieldwork in the high Arctic, with Wollaston Forland being no exception, is the unevenly distributed and sparse vegetation cover. Thus, when the snow melts, a fascinating landscape reveals itself. Alpine mountain peaks and nunataks, glacial valleys, and coastal cliffs, all full of excellently exposed rocks. In our study area in Lindeman Fiord, both Caledonian metamorphic basement rocks, as well as younger sedimentary rocks of predominantly Mesozoic age are present. What is unique with the study area is the Dombjerg Fault, a border fault that juxtaposes syn-rift deep-water hanging-wall clastics against a footwall of crystalline basement (Henstra et al., 2016; Kristensen et al., 2016; see ARCEx archive to download these papers). The fault belongs to a series of east-stepping faults that together define the western boundary of the East Greenland Fault system (Rotevatn et al., 2018). The exposed basin fill succession is also unique in that sense that it represent exhumed deep-marine gravity flow deposits, which accumulated during rifting and possibly rift climax (Henstra et al., 2016). Similar deposits form important reservoirs in several basins along the western margin of the Norwegian Continental Shelf. The aim of the trip was therefore two-fold: one group were to focus on the structural geology and structural diagenesis associated with the Dombjerg Fault, and the second to focus on the sedimentology and diagenesis of the syn-rift strata of the so-called Wollaston Forland Group. Because we also visited the same area back in 2014 during a more regional-scale study, we had pre-designed a detailed plan for which outcrops to visit and what specific sections to focus on. In regards to our late arrival as narrated above, this plan increased the effectiveness of the days we actually spent in the field.

For example, the structural group managed to sample several tens of veins along the Dombjerg Fault itself, and documented the structural fabric within the basin clastics at selected outcrops in a proximal to distal transect normal to the fault. We hope that these samples may reveal the diagenetic history of the fault and basin and tell us what type of fluids that once used the fault and its associated fracture systems as their fairways. For the sedimentology part, the focus this time was to detail the architecture of the syn-rift gravity flow deposits at sub-seismic-scale resolution. In addition to sedimentary logs and rock samples for petrographic analyses, we also collected numerous photos, drone footage and videos so that we can make digital 3D models of our main outcrops. This means that we will be able to enjoy the outcrops in Wollaston Forland from our comfortable office chairs in the years to come. For a small teaser of one of our preliminary models (low resolution), have a look at this video made by Gijs Henstra: https://drive.google.com/file/d/1bh1vHOv9D40mRIF7I4awi5mW3U7AEGxY/view

PS! Just to let you know: we got safely back to Norway after ten fantastic days in the field. So look out for upcoming publications at arcex.no and other forums.

Constable Point (CNP), not the place to spend a long weekend unless you are on the run from the law. Don’t let the picturesque look of the place fool you. The next picture tells the truth.
M&M’s (mud and mosquitos), old storage buildings, fuel tanks and abandoned rusty machines pretty much sums up CNP.
At least we got to practice drone flying while we waited for better weather up north. CNP in the background. The drone turned out to be a great asset to the entire project when we finally got to Lindeman Fiord almost a week later.
‘No professor, this is not a school bus, can you please sit down and let the pilots do their job?’. Finally on our way from CNP towards Lindeman Fiord. Little did we know that two hours later we would end up in the Danish research outpost Zackenberg.
The promissed land. Well, somewhere under the snow. With the fiords still covered by sea ice, we started to wildy speculate amongst ourselves. Would it be possible to land in Lindeman Fiord? How many polar bears can fit on just one of those pieces of ice? Would the polar bears let us alone and simply look upon us as way too skinny seals? How much butter did we bring? The questions and worries were many, but it would later turn out that most of these were irrational.
Welcome to Mars. If you ever have wondered how a Danish Polar station looks like, here is the answer. Zackenberg have their own Twitter account, so if you want to see what they are doing have a look at https://twitter.com/zero74n.
Maybe not a very impressive piece of outcrop, but at least it was enough to increase our moral and satify our urge of getting out to do something useful as a team. View northward up the Lindeman Valley just some 20 km south of our planned camp site in Lindeman Fiord.
Lindeman Fiord plane spotting club. After nearly a week of travelling and waiting, we eventually managed to get to Lindeman Fiord. Here we have unloaded the Twin Otter and are just about to wave farewell to the pilots.
Base camp (BC) in the making. The lavvo served as our common kitchen and living room.
Lindeman Fiord BC in all its glory. The island of Kuhn Ø in the background.
Arctic filedwork is far from a walk in the park. Here Prof. Atle Rotevatn (aka Prof. Longlegs) is crossing a river on his way to the Dombjerg Fault.
Lunch in the field. Syn-rift conglomerates serving as a shelter from the the cold glacier winds down the valley.
A small family of muskox lived closed by our camp, and many times we crossed each others paths in the mountains.
Gijs Henstra looking back towards one of the main outcrops that we digitized (see video link above).
Eric Salomon (left) and Thomas Berg Kristensen (right) samples a vein in a turbidite sandstone.
Weathering of the turbidite sandstones creates a mesmerising landscape out of this World.
Can you spot the muskox?
Eric and Thomas discussing their next move: what outcrops should be prioritized first?
Is that a fossilized cigarette? Nope, just a small piece of a Jurassic (now coalified) plant or a broken branch from a tree that once got transported into the deeper part of the rift basin by a turbidity current. Photo: Eric Salomon.
The majority of the team heading back to camp after a long day in the field.
During daytime, some of the cliffs cast hard shadows, often making it difficult to do proper observations. The hard shadows also made it difficult to collect good photos for our 3D models.
Our solution to the problem with the hard shadows was simply to drone during evenings when the sun was low on the horizon resulting in optimal illumination on the cliff faces. This also meant us spending time in cold, shadow-filled valleys.
Thomas and Gijs on their way back to camp after an evening swim in the fiord. The fog that showed up in our valley two nights before pick-up got us a bit worried. However, the weather gods were on our side and gave us optimal flight weather on the day of departure.
Our last evening in Lindemand Fiord. Perfect conditions for a safe flight back to Iceland.
The team (from left to right): Prof. Atle Rotevatn, Thomas Berg Kristensen, Sten-Andreas Grundvåg, Gijs Henstra, and Eric Salomon. Photo taken by one of the pilots only moments before departing home to safety.
One-Two-Three Take off! Finally homebound.

References:

Henstra, G., Grundvåg, S.-A., Johannessen, E.P., Kristensen, T., Midtkandal, I., Nystuen, J.-P., Rotevatn, A., Surlyk, F., Sæther, T. & Windelstad, J. (2016): Depositional processes and stratigraphic architecture within a coarse-grained rift-margin turbidite system: the Wollaston Forland Group, East Greenland. Marine and Petroleum Geology, Volume 76, September 2016, Pages 187–209. [http://dx.doi.org/10.1016/j.marpetgeo.2016.05.018] [intranet]

Kristensen, T.B., Rotevatn, A., Peacock, D.C.P., Henstra, G.A., Midtkandal, I. and Grundvåg, S.-A. (2016): Structure and flow properties of syn-rift border faults: the interplay between fault damage and fault-related chemical alteration (Dombjerg Fault, Wollaston Forland, NE Greenland). Journal of Structural Geology, Volume 92, November 2016, Pages 99-115. DOI: 10.1016/j.jsg.2016.09.012[intranet]

Rotevatn, A., Kristensen, T.B., Ksienzyk, A., Wemmer, K., Henstra, G.A., Midtkandal, I., Grundvåg, S.-A. & Andresen, A. (2018) Structural inheritance and rapid rift-length establishment in a multiphase rift: the East Greenland rift system and its Caledonian orogenic ancestry. Tectonics, 2018, Vol.37(6), p.1858-1875. DOI: 10.1029/2018TC005018 [intranet]

 

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