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RE: Gardnos impact structure
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Gardnoscraterb.jpg
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Latitude; 60.717178° N Longitude; 8.823509° E


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Gardnos crater
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Gardnos is a meteorite impact crater in the area known as Nesbyen in Hallingdal, Norway. It is 5 km in diameter, and was created when a meteorite with an estimated diameter of 200-300 m struck 500 million years ago
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Gardnos impact structure
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Title: SEDIMENTARY INFILL OF THE GARDNOS IMPACT CRATER – A FIELD REPORT
Authors: E.Kalleson, H.Dypvik, J.Naterstad.

The Gardnos impact structure in Hallingdal is one of only two (at present) confirmed impact craters in Norway, the other being the Mjølnir crater in the Barents Sea. Ar40/Ar39-dating failed due to Caledonian overprint, but the age of this impact crater is probably late Precambrian, based on field information. The exact timing of the impact event is still a topic for further research. As it appears today, the Gardnos structure is roughly circular with a diameter of about 5 km. The structure is exposed through Tertiary and recent regional uplift, weathering and erosion. During Quaternary time the area was repeatedly covered by glaciers and consequently large parts of the crater structure is covered by moraine. There are however, good exposures at steep hillsides and along river beds.
A 400 m long core was drilled within the Gardnos structure in 1992, penetrating sediments and impactites (suevite and Gardnos breccia).
The main focus so far in the investigation of the Gardnos structure has been the geochemistry of the impactites.

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Title: Survival of reactive carbon through meteorite impact melting
Authors: John Parnell, Paula Lindgren

Melt fragments in melt breccias from the Gardnos impact crater, Norway, contain abundant carbon. A high proportion of the carbon present in the original melt was preserved. The stripping of hydrogen from carbon during melting prevents later hydrocarbon formation, hence the carbon is fixed in place rather than volatilised. Underlying lithic breccias that were not melted record hydrocarbon generation as a response to less extreme heating. Despite the high-temperature history of the melt, the carbon from the Gardnos impact crater is highly disordered, rather than ordered crystalline graphite, and in this respect, it is comparable with carbon in chondrite chondrules. Disordered carbon bears functional groups upon weathering, and, therefore, carbon preserved through impact or other melting may be available for reworking into biologically relevant organic molecules.

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Gardnos
Latitude; 60.717178° N Longitude; 8.823509° E
5 km diameter impact crater, 500 ± 10 millions years old

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