Gardnos, breccia

3D ModelNoAI

The Gardnos impact structure in southern Norway is a heavily eroded ~5 km diameter impact crater. The age of the crater was difficult to constrain as geologic processes placed it between the metamorphic age of the basement rock (~900 million years old) and the Caledonian mountain forming period (~385 million years). However, the timing has been refined using dating of zircon minerals that places the impact around 540-551 million years ago. Impact breccias are found in both lithic and meld-bearing varieties. What really stands out is their high carbon content compared to other impact structures. It is also 5-10 times higher relative to the surrounding bedrock. This makes Gardnos an interesting case to study the dynamics of carbon during impacts (relevant for example, in the context of the origins of life). It illustrates that carbon is not lost due to oxidation during impacts and it can be preserved (Lindgren et al., 2019)