The Popigay ( Russian : Попигай ) is a river in Krasnoyarsk Krai , Russia . It is a right tributary of the Khatanga . The length of the river is 532 kilometers (331 mi). The area of its drainage basin is 50,300 square kilometers (19,400 sq mi). The river has its source in the Anabar Plateau . It freezes up in October and breaks up in June. Its main tributaries are the Rassokha and Fomich .
6-587: The river passes by the Popigay crater , about 900 kilometers (560 mi) northeast of Norilsk . This Krasnoyarsk Krai location article is a stub . You can help Misplaced Pages by expanding it . This article related to a river in the Russian Far East is a stub . You can help Misplaced Pages by expanding it . Popigai impact structure The Popigai impact structure is the eroded remnant of an impact crater in northern Siberia , Russia. It
12-581: Is tied with the Manicouagan structure as the fourth largest verified impact structure on Earth . A large bolide impact created the 100-kilometre (62 mi) diameter crater approximately 35 million years ago during the late Eocene epoch ( Priabonian stage ). It might be linked to the Eocene–Oligocene extinction event . The structure is 300 km (190 mi) east from the outpost of Khatanga and 880 km (550 mi) northeast of
18-539: The city of Norilsk , NNE of the Anabar Plateau . It is designated by UNESCO as a Geopark , a site of special geological heritage. There is a small possibility that the Popigai impact crater may have formed simultaneously with the approximately 35-million-year-old Chesapeake Bay and Toms Canyon impact craters. For decades, the Popigai impact structure has fascinated paleontologists and geologists , but
24-399: The entire area was completely off limits because of the diamonds found there. However, a major investigatory expedition was undertaken in 1997, which greatly advanced understanding of the structure. The impactor is suggested to have been a H chondrite asteroid based on ejecta layers from Italy, with the impactor thought to have been several kilometeres in diameter. The shock pressures from
30-555: The impact instantaneously transformed graphite in the ground into diamonds within a 13.6 km (8.5 mi) radius of the impact point. These diamonds are usually 0.5 to 2 mm (0.020 to 0.079 in) in diameter, though a few exceptional specimens are 10 mm (0.39 in) in size. The diamonds inherited the tabular shape of the original graphite grains and also the original crystals' delicate striations . Most modern industrial diamonds are produced synthetically . The diamond deposits at Popigai have not been mined because of
36-417: The remote location and lack of infrastructure, and are unlikely to be competitive with synthetic diamonds. Many of the diamonds at Popigai contain crystalline lonsdaleite , an allotrope of carbon that has a hexagonal lattice. Pure, laboratory-created lonsdaleite is up to 58% harder than ordinary diamonds. These types of diamonds are known as "impact diamonds" because they are thought to be produced when
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