Scientists from Kazan Federal University (KFU) have identified patterns in the distribution of rare and rare earth elements in the Visean terrigenous and coal-bearing deposits of the Melekes Depression (including the territories of Tatarstan, Samara, and Ulyanovsk regions), which are approximately 350 million years old. The study was based on the analysis of dozens of cores from well 1955 (Nizhny-Nurlatskaya), which were stored at the university, TASS was informed by the press service of the Ministry of Education and Science of Russia.
The analysis showed a pronounced vertical zonation of the chemical composition of the rocks: the sequential change of sedimentation intervals reflects the transition from deep-sea marine conditions to shallow-sea marine conditions. The press service noted that this allows for the reconstruction of the paleoenvironment of the territory and the prediction of zones of enrichment with rare and rare earth elements in the Visean coal-bearing and terrigenous strata. The obtained data show where the seas, swamps, or other ecosystems were located.
In the zones of the ancient sea with oxygen-rich water, the rocks contained more strontium and molybdenum, while in the swampy areas with low oxygen content, the concentration of lithium, zirconium, hafnium, and rare earth elements increased. Researchers associate the spatial distribution of rare earth metals (REE) with the intensity of pore water exchange and the activity of burrowing organisms that loosened the sedimentary strata.
KFU plans to expand research on the Carboniferous deposits of the Volga-Ural region to clarify the patterns of concentration of rare elements on the scale of the entire region. This information is important not only for geological mapping but also for the search for strategically important resources needed for industry and high technology.