Obukhov Formation

Obukhov Formation
Stratigraphic range: Late Eocene PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Underlies	Mezhigorje Formation
Overlies	Early Eocene Basement
Thickness	2–7 m (6.6–23.0 ft)
Lithology
Other	Sand, Clay, Amber, Glauconite, Quartz
Location
Location	Ukrainian Crystalline Shield
Region	Belarus (Gomel Region) Ukraine (Rivne Oblast)

The Obukhov Formation is a geologic formation in Belarus and Ukraine that dates to the Late Eocene;[1] the Obukhov Formation is equivalent to the Prussian Formation of Russia.

Rovno amber is found in this formation,[2] and 90% of amber collected from the Obukhov Formation is extracted illegally and the trade is controlled by armed organised crime groups.[2]

Geological context

The Late Eocene Rovno amber is hosted in the Obukhov Formation, and it underlies the Early Oligocene Mezhigorje Formation.[3][2] The formation is found along the northwestern margin of the Ukrainian Crystalline Shield[1] exposed in the Rivne region of Ukraine and across the border near Rechitsa in the Gomel Region of Belarus.[4] The granite basement rock was overlain by sandy to clayey deposits that were host to alluvial amber.[2]

The two formations total between 2–7 m (6.6–23.0 ft) in thickness, both containing interbeds or mixtures of brown coals and carbonized vegetation. Both formations are sandy to clayey in texture, with the Obukhov Formation having more clayey glauconite-quartz plus sandy loess.[5]

References

1. Engel, M.S.; Perkovsky, E.E. (2006). "An Eocene bee in Rovno amber, Ukraine (Hymenoptera, Megachilidae)" (PDF). American Museum Novitates (3506): 1–11. doi:10.1206/0003-0082(2006)506[0001:aebira]2.0.co;2. S2CID 84073810.
2. Perkovsky, E. E.; Zosimovich, V. Y.; Vlaskin, A. P. (2010). "Chapter 7: Rovno amber". In Penney, D. (ed.). Biodiversity of Fossils in Amber from the Major World Deposits. Siri Scientific Press. pp. 116–136. ISBN 978-0-9558636-4-6.
3. Perkovsky, E. E.; Rasnitsyn, A. P.; Vlaskin, A. P.; Taraschuk, M. V. (2007). "A comparative analysis of the Baltic and Rovno amber arthropod faunas: representative samples". African Invertebrates. 48 (1): 229–245.
4. Perkovsky, E. E. (2017). "Rovno Amber Caddisflies (Insecta, Trichoptera) from Different Localities, with Information about three New Sites". Vestnik Zoologii. 51 (1): 15–22. doi:10.1515/vzoo-2017-0003.
5. Perkovsky, E. E.; Zosimovich, V. Y.; Vlaskin, A. P. (2003). "A Rovno amber fauna: a preliminary report". Acta Zoologica Cracoviensia. 46(Supplemental): 423–430.