The geochemistry of water and gas phases from high pCO₂ sparkling springs within the northern Sikhote-Alin ridge region (Russian Far East)

Abstract

Two types of cold CO2 rich groundwaters are located within the northern part of the Sikhote-Alin ridge: the first type is a Ca–Mg–HCO3 water with low TDS content (≤ 1.7 g/l) and high concentrations of Fe2+, Mn2+, Ba2+, and SiO2, whilst the second type is a Na–HCO3 water with a high TDS content (≈ 14 g/l) and elevated concentrations of Li+, Btot, Sr2+, Br–, and I–. A notable feature of these waters is a predominance of CO2 in the gas phase (up to 99 vol. %) and low contents of other gases (CH4, N2, O2, etc.). The origins of both water types can be identified on the basis of water (δD, δ18O) and gas (δ13C, 3He/4He, 4He/20Ne) isotopic compositions considered in the context of the geology and hydrology of the region.

Upwelling of Deep-seated Fluid in the Sikhote-Alin Region, Far East of the Eurasian Plate

“…In Fig. 5, the He isotopic compositions are shown for both aquifers in the Mukhen springs (Kharitonova et al 2019), compared with the newly obtained data by this study for several springs in the far eastern region (Table 2). The locations of the springs are shown in the inset of Fig.…”

“…With respect to the genesis of high-pCO 2 water, several mechanisms associated with young volcanism have been suggested, and several studies have shown that most high-pCO 2 waters have a meteoric origin (Kharitonova et al 2017). Recently, Kharitonova et al (2019) observed a high 3 He/ 4 He ratio in the Mukhen springs, indicating that these springs originated from a considerable depth. The He isotopic system is a strong indicator to distinguish the contributions from various sources, particularly those from crustal and mantle rocks.…”