Evidence of Microbial-Induced Mineralization in Rocks of the Tomtor Carbonatite Complex (Arctic Siberia)

Carbonates of the Tomtor complex of ultramafic alkaline rocks and carbonatites (the northern part of the Republic of Sakha Yakutia) are distinguished by a wide range of carbon isotopic composition δ13C from +2 to –59.9‰. The geological position, localization patterns, mineral and chemical compositions and the relationship with REE mineralization of samples with values of δ13C carbonates from –25 to –59‰ are characterized. The formation of abnormally low δ13C in carbonates is determined by the biogenic oxidation of methane from δ13Cmet to –70‰.