Strontium Isotope Composition of Mud Volcanic Waters in Azerbaijan

Resumo

The Sr isotope composition was studied in waters from 22 mud volcanoes in Azerbaijan, where the O and H isotope compositions, as well as concentrations of macro- and microelements, were determined earlier in (Lavrushin et al., 2015). Values of the ⁸⁷Sr/⁸⁶Sr ratio in the Azerbaijanian mud volcanoes range from 0.7067 to 0.7083. Its minimum value was recorded in water of Neftechala Yuzhnaya Volcano located in the southern area (Kura region), where volcanoes are generally characterized by low average values of ⁸⁷Sr/⁸⁶Sr (0.7070 ± 0.0003) and δ¹⁸O (2.0 ± 1.8‰), in contrast to volcanoes located in the northern area (Shemakha‒Gobustan, Apsheron, and Caspian regions) with ⁸⁷Sr/⁸⁶Sr = 0.7076 ± 0.0005 and δ¹⁸O = 4.8 ± 2.5‰. Ratios of the Sr and O isotope compositions of mud volcanic waters in Azerbaijan suggest that isotope characteristics of these waters are related to two major sources: the first source is related mainly to Cretaceous‒Paleogene sedimentary carbonates, whereas the second source dominating in the Kura region bears the signs of isotope exchange with volcanic rocks. The role of Sr dissolved in sea water and of Sr, which could be extracted from the recent terrigenous sediments in the Caspian Sea and the Maikopian terrigenous clayey rocks, is negligible in the Azerbaijanian mud volcanic waters.