Kara Crater

The first mention of geological anomalies and the unusual structure of the Kara estuary area dates back to the 1904 Baklund expedition, which discovered breccias on the Kara River, but carried them to the Tillites. In the future, researchers, until the end of the 60s of the XX century, were inclined to the volcanogenic-tectonic origin of the Kara depression , which appeared as a result of explosive eruptions of the Bandaisai type . However, the findings of signs of impact metamorphism made in the 70s and further geological and geophysical studies of the deep structure made it possible to confirm the impressive hypothesis of its formation ^[1] .

The structure of a round shape, with a negative macro-relief (a hollow with a diameter of 50-56 km), according to modern concepts, is one of the largest meteorite craters in the world . The structure is formed in the complexly distributed Paleozoic rocks. As a result of lengthy processes, it was transformed into the sloping Kara depression, opening to the northeast, to the Kara Sea .

In its composition, a central uplift of 7 × 9 km in size is distinguished, in which Ordovician deposits with sills of late Devonian age protrude onto the surface; it is surrounded by an annular groove 17-26 km wide. The lack of strict ring symmetry of the crater funnel is associated with the differentiated neo-Ohenogenic rise of the Pai-Khoi in the Cenozoic (especially in the Pliocene) and, as a result, with the predominant uplift and denudation of the southwestern part of the crater compared to the northeastern one. Basement rocks are fragmented and plastically deformed; fracture cones up to 2 m high are characteristic.

In the modern structure, the copogenic formations are overlain by the Late Cretaceous and Cenozoic sedimentary rocks, they are revealed along the edges of the astrobleme in deep river valleys. In the gravitational field, the astroblem corresponds to the “Ust-Kara gravitational minimum” ^[2] . In the impactites of the Kara structure, diamonds are present ^[3] .

Estimates of the age of the crater range from 73 to 55 million liters. n The most correct data are recognized as isotopic dating of glasses, giving a result of 65.5–66.1 million liters. BC, that is, Late Cretaceous at the boundary with the Paleogene ^[4] .

• List of impact craters in Russia

• Description of the crater on the website of the Siberian Center for Global Disasters at the Russian Academy of Sciences (Neopr.) (Inaccessible link) . Archived February 21, 2008.