South Greenland – warmth, trees, and mosquitoes |
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To the left, Ellen’s pack covered with mosquitoes – the little dots are just a small number of them. To the right, Philip is sampling water from the Kiagtuut sermiat drainage – a proglacial stream shown by the turbid water. He’s modeling mosquito netting – the height of fashion in south Greenland. |  |
Aerial images of the landscape |
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To the left is an aerial view, flying over the glacier Kiagtuut sermiat looking south toward Narsarsuaq, during our helicopter trip into our distal deglaciated watershed, Qoornup Kuua. To the right right is the Qoornup Kuua valley that drains the old (10 ky) moraine representing continental ice sheet retreat. Although warm in town, the lakes on the plateau remain frozen. |  |
| On the right is the proglacial drainage to the fjord. The turbid water is clearly visible as the white-pale blue water bounded to the left with the darker blue water of the fjord. The interface between the two water masses was not sharp at small scale and we suspect this boundary may be the location of biogeochemical reactions as the different water compositions mix. |  |
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| Mixing also occurs as the deglaciated drainages flow into the proglacial drainages. To the right is a picture of us sampling a mixing zone of the RT watershed near the head waters of Kiagtuut sermiat. Mixing between the deglaciated and proglacial watersheds appears to promote algal growth and we assume the productivity there results from mixing of different nutrients from the two different watersheds. | ||
Heterogeneous lithology |
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  The image to the right shows what we believe is a basaltic dike (dark rock) intruded into syenite (lighter rock) that makes up much of the outcrops around here. |
The geology of this region is much more complicated than our northern sites. It contains granites from subduction that occurred approximately 1800 my ago (Ketalinian rocks), followed by a rifting event about 1.3 to 1.1. my ago in which sedimentary rocks are mixed with basaltic dikes (Gardar Group rocks). To the left is a zoned plagioclase crystal. To the right and below left are images sandstones. The image on to the right shows variable redox states (red and green layering). The lower image on the left appears to have ripple marks.
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Our preliminary water chemistry reflects the changes in lithology. The pH is higher than in the Kanger-Sisimiut region to the north and the alkalinity is much more variable. The proglacial river appears to be highly undersaturated in CO2 – it is adsorbing CO2 from the atmosphere. The deglaciated rivers are both adsorbing and degassing CO2 depending on the particular lithology they are draining. More to come as data are collected back in the lab…. |