Kazan Federal University scientists established patterns of distribution of rare and rare-earth elements in ancient rocks

Scientists from the Department of Paleontology and Stratigraphy have identified patterns in the distribution of rare and rare-earth elements in the Visean terrigenous and coal-bearing deposits of the Melekess Depression (Kama Coal Basin, Volga-Ural subregion).

The obtained results are presented in an article published in the Vestnik of the North-East Scientific Center of the Far-Eastern Branch of the Russian Academy of Sciences.

Having examined dozens of core samples from well 1955 (Nizhne-Nurlatskaya) stored at the Institute of Geology and Petroleum Technologies (IGPT), the scientists recorded a distinct vertical zonation in the chemical composition of the rocks. It was established that the successive change in sedimentation intervals reflects a transition from relatively deep-water marine environments to shallow-marine settings.

“The study of the Visean terrigenous and coal-bearing deposits of the Melekess Depression, which are approximately 350 million years old, allowed us to establish the distribution patterns of rare and rare-earth elements within them. These patterns allow us to determine what existed in the studied territory in those distant times: a sea, a swamp, or something else. The obtained data are important for forecasting zones of enrichment with rare and rare-earth elements in Visean coal-bearing and terrigenous strata,” explains the article’s first author, Milyausha Urazaeva, Associate Professor at the Department of Paleontology and Stratigraphy.

Where there was an ancient sea with oxygen-rich water, the rocks accumulated more strontium and molybdenum, Urazaeva clarifies. Conversely, where there were swamps and a significant oxygen deficiency, elevated contents of lithium, zirconium, hafnium, and rare-earth elements are observed. According to the researchers, the spatial distribution of these minerals is conditioned by the intensity of pore water exchange in sedimentary strata and the abundance of burrowing organisms that disturbed the sediment.

The project is supported by a grant from the Academy of Sciences of the Republic of Tatarstan for young Candidates of Sciences (postdoctoral researchers).

In the future, the scientists plan to investigate how rare and rare-earth elements are distributed in the Carboniferous deposits of the Volga-Ural region.