With our sample box yet to arrive, we focus today on geological sampling. Specifically, we are after samples that represent the main basaltic units present on Disko Island, with which unusual iron-bearing basalts, and basalts containing reduced carbon species, are associated. We hope that by sampling these surrounding units (all of which make up the same overall geological complex), new clues can be uncovered as to the formation of these unusual basalts. We begin our basalt-hunt at a nearby mountain called Scarvefjeld (Innarsuaq), a climb of 861 m from our base at sea level.
Although only a couple of miles away, the terrain underfoot is incredibly difficult. Our two options once we leave the well-trodden path close to Arctic Station are overgrown marsh down in the valley, or steep rocky scree along the flanks of Scarvefjeld. We decide to start off on the rocky flanks, as this provides us with the opportunity to check out the basaltic lithologies that have fallen from the intact lava flow units high up above. Eventually after a 6 hour hike we come to an area suitable for sampling, where we can access in situ lava flows and the fresh fallen material further down the slopes.
Here we find two distinct types of basalt. The first type is highly vesicular, with large vugs and voids in-filled with secondary mineralisation. The second type is completely different, and is incredibly fine-grained with phenocrysts of unusual black, shiny minerals. This is from the Akuarut unit, which is unusually high in iron and titanium.
As we become aware of time slipping away, after sampling we decide to head back down the steep slopes of Scarvefjeld towards the valley below. Walking along the scree was difficult, so this time we make the decision to return along the marshy valley floor. In doing so, we also sample a low-lying unit of the Rinks Dal basalt, which is identical to the vesicular, mineralised basalts we sampled earlier in the day, confirming these samples to be of the same unit. Our hike back to Arctic Station is long and difficult – the marshy ground is incredibly unforgiving and the lack of defined routes means we have to double-back on ourselves a lot in order to find a sensible path down. Finally home after 10.5 hours of solid hiking, we make up for the long day with a hefty serving of Musk Ox chilli.