Logancha
Key facts
- Country
- Russia
- Diameter
- 20 km
- Age
- about 40 ± 20 million years
- Location
- 65.52° N, 95.93° E
A round basin about 20 km across in the remote taiga of the Evenk district, central Siberia, cut into the flat-lying lava plateau of the Siberian Traps.
Logancha is an eroded impact structure about 20 km across in the remote Evenk district of central Siberia, Russia, north of the Lower Tunguska River.
What it hit. The impactor struck the Siberian Traps, an enormous pile of basalt lava flows and associated sediments, erupted about 250 million years ago in one of the largest volcanic events in Earth's history. Logancha is therefore one of the few impact structures on Earth formed in basalt, the rock that makes up the dark plains of the Moon and much of the surface of Mars.
Proof of impact. Soviet geologists studying the round basin found breccias, impact melt rocks and minerals with shock features, which confirmed an impact.
Age. The age is poorly known. Estimates of about 40 million years, in the Eocene, have an uncertainty of about 20 million years.
Why it matters. Logancha is valuable for understanding how impacts affect basalt, and it has been compared with craters on the Moon and Mars. The impactor is unknown.
Visiting. The area is very remote taiga, accessible only by helicopter or river expedition.
Did you know?
Logancha formed in the basalt lavas of the Siberian Traps.
Basalt like that at Logancha covers the dark plains of the Moon.
The area is so remote that it can be reached only by helicopter or river.