Suvasvesi South
Key facts
- Country
- Finland
- Diameter
- 3.8 km
- Age
- about 710 million years
- Location
- 62.60° N, 28.22° E
Haapaselkä, a round basin of the lake Suvasvesi in eastern Finland, a few kilometres south of its northern twin.
Suvasvesi South is an impact structure about 3.8 km across beneath Haapaselkä, the southern part of the lake Suvasvesi in eastern Finland.
Discovery. After Suvasvesi North was confirmed in 2001, geologists suspected that the similar-looking basin to the south might also be a crater. They found impact melt rock in boulders and outcrops near the south-eastern shore, with shock features in its minerals, confirming an impact.
What it hit. The impactor struck crystalline rocks of the Baltic Shield, mainly gneiss and granite.
Age. Argon dating of the melt rock gives an age of more than 700 million years, probably about 710 to 720 million years. An earlier estimate of about 250 million years has been revised.
Not twins after all. The two Suvasvesi craters look like a pair made at the same moment by a double asteroid. In fact, their ages differ by hundreds of millions of years, showing that two separate impacts struck almost the same place by coincidence. The Clearwater Lakes in Canada turned out to be a similar case.
Why it matters. Suvasvesi South shows that a pair of craters side by side need not be twins: only careful dating can tell. The impactor is unknown.
Did you know?
Suvasvesi South and North look like twins but formed hundreds of millions of years apart.
Melt rock near the shore confirmed the impact.
The crater is probably about 710 million years old.