Dobele
Key facts
- Country
- Latvia
- Diameter
- 4.5 km
- Age
- about 290 ± 35 million years
- Location
- 56.58° N, 23.25° E
Nothing: the structure is buried beneath the flat farmland of the Zemgale plain near the town of Dobele, in western Latvia.
Dobele is a buried impact structure about 4.5 km across near the town of Dobele in western Latvia. It is the only known impact structure in the country.
Discovery. The structure was found through drilling and geophysical surveys in the second half of the twentieth century. Boreholes showed that the normally flat-lying sedimentary layers beneath the plain were disturbed in a round area, with a central uplift and a depressed ring. Quartz grains with shock features in the breccia confirmed an impact.
What it hit. The impactor struck a thick sequence of Palaeozoic sedimentary rocks, mainly Devonian sandstones, clays and carbonates, which cover the crystalline basement of the region. Later sediments and glacial deposits of the ice ages buried the structure.
Age. The youngest rocks disturbed by the impact are Carboniferous, and the oldest undisturbed rocks lying over it are younger, so the impact is dated to about 290 million years ago, give or take about 35 million years.
Why it matters. Dobele is one of a group of buried impact structures in the Baltic countries, along with Mizarai and Vepriai in Lithuania and Kärdla and Neugrund in Estonia, revealed by the dense network of boreholes drilled in the region. The impactor is unknown.
Did you know?
Dobele is the only known impact structure in Latvia.
It was found through boreholes, not from anything at the surface.
Glacial deposits completely hide the structure.