Monday June 24, 2013

This week was all about sediment description and core logging. We visited three different sites and described a rock core, which is part of an ongoing project at UNIS. This week the focus of the class shifted to coastal environments in the modern and ancient sedimentary record. Bernadette Tessier, an expert on tidal systems and researcher from the University of Caen in France, was the invited lecturer for the week.

During Monday’s lecture we discussed continental shelf deposits, deltas, and tidal settings. Bernadette shared the results of a recently published study on the southern coast of the English Channel. By analyzing sediment cores and seismic profiles they found evidence of enhanced storm activity happening every 1500 years during the late Holocene, an occurrence that has been documented in other parts of the North Atlantic. In the afternoon, we visited the outcrops right next to the main road in Longyearbyen to draw our first stratigraphic column. These outcrops form part of the Carolinefjellet Formation, a marine succession composed of interbedded shales and sandstones deposited during the lower Creataceous.

On the second day, we traveled by zodiac (small rubber boat) to Deltaneset, located 15 km northeast of Longyearbyen, on the south edge of Isfjorden. The area is characterized by small capes or headlands with outcrops in the inner side that are usually exposed during the summer, usually. Unfortunately for us, most of the outcrops were covered by a lot of snow and so our first task of the day was to walk along the gravelly beach to find exposed outcrops suitable for vertical logging. It was a long walk but we found three good sites, with some snow but little enough to shovel. The outcrops correspond to the continental De Geerdalen Formation (upper Triassic). The surface is covered by cobbles and boulders, up to a meter in diameter. These have been carried by snow avalanches and debris flows from the nearby hills. A contrasting view is the soggy soil; some areas are very damp because the uppermost portion of the permafrost is thawing due to the summer warmth.

Students walking along the beach, next to snow-covered outcrops at Deltaneset.

 

The boat ride can be cold and wet and therefore students are required to wear dry suits for safety.

The following day we did not go out to the field, instead we spent the day describing and logging a segment of a rock core from the De Geerdalen Formation. The core is part of the UNIS CO₂ capture and storage research project. They have drilled 6 wells and are currently studying 4 of them for reservoir characterization. The objective of this project is to evaluate the possibility of storing carbon dioxide in the Adventdalen valley, about 5 km outside of Longyearbyen. Several master and PhD students as well as senior researchers from UNIS form part of the project. Our job was to describe the sediment, divide into facies, create facies associations, and then interpret the facies. Overall, the segment was a coarsening upward section, from muddy bioturbated to sandy cross-bedded sediments possibly indicating either transgression or lateral migration of the environment.

Student logging a 5-meter section of a core.

Adventdalen valley, approximately 5 km across with an estimated 60 meters of quaternary fill.

Thursday was a field day, we went to Endalen. A U-shaped valley located just outside of the city, with a braided river tributary to Adventfjorden. Again, the task of the day was to draw a stratigraphic column but this time the outcrops were at an elevation of nearly 400 meters along the sides of the valley. Needless to say, it took me and a couple of other students some time to hike up to the outcrops. Once there, we realized we were looking at continental deposits, in fact we were describing the same coal seams that are currently mined in other areas in Svalbard. The coal deposits correspond to the Tertiary period and in total there are five in Svalbard but only two are economically workable, one in Longyearbyen and the second one in Svea. The outcrops were also characterized by soil horizons alternating with sandstones. 

Students taking a break while hiking up in Endalen. 

Students measuring and describing a section in Endalen.

The temperature last week was higher, after all we are now in summer, it averaged around 5°C and it is expected to increase a little more. This week we will be traveling to Svea, about 60 km south of Longyearbyen, to study coastal and glacial deposits. 

Mine 2 located in Longyearbyen, now abandoned but still a must see in the city.

 

Longyearbyen and Adventfjorden, view from mine 2.