Geo&Bio (Dec 2020)
Transition of plant resins from the biosphere to the lithosphere
Abstract
In the article the authors consider in detail the process of transition of plant resins from the biosphere to the lithosphere, characterize the conditions and paleogeographic situation of such transition, the formation of deposits of resin minerals and placers of amber-succinitis in particular. The subject of research is the territory of the modern Dnipro brown coal basin within the Ukrainian Shield and its slopes, covering the border areas of the Pripyat Depression, Dnipro-Donetsk and Black Sea depressions, Volyn-Podilsk plate as a promising object of amber-succinitis genesis. A comprehensive geological and paleogeographic analysis of the natural conditions of this region in the Eocene-Oligocene was given. At that time, resin secretions of mainly conifers were accumulating in this area and transformed into fossil resins, which allowed the authors to distinguish three temporary stages of fossilization (fossilization and transformation) of the plant soft resin on the long path of transition from wildlife to inanimate. It was found that the fossilization of plant resins occurred in land-bog and marine stages under conditions of diagenesis. The first took place in the lower half of the Middle Eocene (the Lutetian); the second — in the post-Buchak time at the end of the Middle-Upper Eocene — Early Oligocene; the final stage is associated with the transformation of amber-succinite in the late diagenesis (Eocene-Oligocene) and catagenesis (Anthropogene) at low temperatures and pressure. For the first time, the primary source of amber-succinitis placers was identified, which was formed at the first, land-boggy stage of fossilization of plant resins. It is represented by biogenic-sedimentary deposits of resin secretions in peat bogs (proto-amber), underlying the "amber forests" and at some distance from them. The erosion of primary deposits took place in the post-Buchak time. The proto-amber taken from the primary sources was transported by river waters to the sea basin, where in a glauconite-containing medium, it acquired the properties of amber-succinitis. Establishment of the primary source of amber-succinite placers completely determines the scientific and practical significance of the research carried out, ultimately aimed to forecast deposits.
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