Waters from mud volcanoes of Azerbaijan: Isotopic-geochemical properties and generation environments

Geochemistry of fluids discharged from mud volcanoes in SE Caspian Sea (Gorgan Plain, Iran)

“…Nevertheless, secondary SO 4 2could be produced through H 2 S oxidation at relatively shallow depth. In the δD-H 2 O vs. δ 18 O-H 2 O diagram (Figure 10), where the local-meteoric water line (LMWL; Shamsi and Kazemi 2014) was reported, the Gorgan Plain waters were compared to those from Azerbaijan (Lavrushin et al 2015) and Turkmenistan MVs (Lavrushin et al 2005). The Gorgan Plain waters show significant enrichments in δ 18 O and δD values with respect to LMWL and seem to be aligned along an evaporation trending line.…”

“…They are mostly associated with hydrocarbon fields within hydrocarbon-bearing faulted anticlines (Guliyev and Feizullayev 1996;Fowler et al 2000). The geochemistry of fluids discharged from the South Caspian Basin MVs, including those exposed in Cheleken peninsula (western Turkmenistan) and Azerbaijan were extensively studied (Planke et al 2003;Davies and Stewart 2005;Mazzini et al 2009;Oppo et al 2014;Lavrushin et al 2015). The Oligocene-Early Miocene Maykop Formation, including layers of anoxic fine-grained and organic-rich sediments (Abrams and Narimanov 1997;Hudson et al 2008), is to be regarded as the main fluid source (Figure 2; Inan et al 1997;Fowler et al 2000).…”

“…δD vs. δ 18 O values of MV waters from Gorgan Plain, Azerbaijan, Turkmenistan, Caspian Sea and Seawater(Lavrushin et al 2005(Lavrushin et al , 2015 compared with the Local Meteoric Water Line (LMWL)(Shamsi and Kazemi 2014). The dashed line refers to the isotopic variation trend of the Gorgan Plain MVs.…”

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“…For example, the boron concentration can reach up to 1636 mg/l in the waters of the Kerch Peninsula volcanoes [Sokol et al, 2019]. It is believed that the enrichment of mud volcanic waters in boron occurs as a result of its desorption from clay minerals during the smectite transformation into illite [Lavrushin et al, 2015;Sokol et al, 2019]. Apparently, the observed variations in the boron content in the waters of mud volcanoes of Sakhalin Island reflect the varying degrees of post-sedimentary transformations occurring in the "water-rock-gas" system.…”

“…The similar estimates for the South Sakhalin and Pugachev volcanoes are noticeably higher: within the ranges of 81-151 and 69-136 °C, respectively. The Mg-Li geothermometer, which was specially developed for the waters of sedimentary basins of the wide mineralization range, is considered the most suitable for calculating the formation temperatures of mud volcanoes [Lavrushin, 2015]. The estimates of the depth of occurrence of mud volcanic chambers were made based on the values of temperatures obtained by the Mg-Li geothermometer and the magnitude of the geothermal gradient in the studied area [Veselov et al, 1997].…”