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

¹ Lomonosov Moscow State University, Faculty of Geology, Moscow, Russia
² Far East Geological Institute, FEB RAS, Vladivostok, Russia
³ Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology
⁴ Japan Agency for Marine-Earth Science and Technology
⁵ Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Japan
⁶ Ocean Resources Research Center for Next Generation, Chiba Institute of Technology, Japan
⁷ Earthquake Research Institute, the University of Tokyo, Japan
⁸ Geological Institute, RAS, Moscow, Russia

^* Corresponding author: tchenat@mail.ru

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⁺, B_tot, 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.