Mud Volcanic Fluids of the Kerch–Taman Region: Geochemical Reconstructions and Regional Trends. Communication 1: Geochemical Features and Genesis of Mud-Volcanic Waters

Abstract

The chemical and isotopic characteristics (δ 18 O and δ 2 H) of water from 42 mud volcanoes of the Kerch-Taman region (Crimean-Caucasus district) were analyzed. The formation temperatures of mud volcanic waters were estimated using the Mg-Li hydrochemical geothermometer (t(Mg-Li) = 40-134°C). It was revealed that dehydration waters released during the smectite-to-illite transformation play significant role in the total fluid balance of the mud volcanic systems (up to 80% of the total fluid volume). These waters are characterized by low Cl ion contents, δ 18 O from +13 to +17‰, and δ 2 H from -25 to -20‰ relative to VPDB, and high concentrations of , B, Li, Ba and other trace elements. Correlations between the concentration of HCO 3 , B, δ 18 O, and t(Mg-Li) values were revealed.

Phenotypic and genomic characterization of the first alkaliphilic aceticlastic methanogens and proposal of a novel genus Methanocrinis gen.nov. within the family Methanotrichaceae

“…Strain M04Ac is isolated from a mud volcano located within the Kerch-Taman mud volcanic province. Many TMVs in this area have pH 8.5–9.1 and contain high concentrations of HCO and Na + ions (Lavrushin et al, 2021 ). The presence of Methanotrichaceae species had not previously been detected by 16S rRNA gene-based observations in several TMVs of this region (Merkel et al, 2021 ; Khomyakova et al, 2022 ; Slobodkin et al, 2023 ).…”

“…The archaeal part of the TMVs microbial communities usually contains many anaerobic methane-oxidizing archaea (ANME) and a small number of methanogens (Alain et al, 2006 ; Niederberger et al, 2010 ; Merkel et al, 2021 ; Tu et al, 2022 ). Mud volcanic fluids of the Kerch–Taman region often have high pH values due to a presence of sodium carbonates (Lavrushin et al, 2021 ). To date, neither methanogens nor any Archaea from TMVs were obtained in a pure or highly purified culture and physiologically characterized.…”