Home – Home – Jornals – Russian Geology and Geophysics 2019 number 11

We consider the factors determining the mineral composition of hydrothermal clays in recent thermal anomalies of the Pauzhetka-Kambal’nyi-Koshelevskii region and Ebeko (Paramushir Island) and Mutnovskii Volcanoes. The composition of mineral assemblages is influenced by a number of interdependent factors: the type of discharge (steam-gas jets, heated grounds, and mud water pools), temperature, pH, and Eh of a thermal solution. Mineral assemblages including sulfur, opal, α-quartz, and alunite group minerals form on the heated grounds of the craters of active volcanoes (Ebeko and Mutnovskii). Mud water pools of the craters contain mainly sulfur, opal, and α-quartz. An assemblage of kaolinite, opal, alunite group minerals (in small amounts), and goethite forms in mud water pools with pH = 2-3 in the thermal fields of the Pauzhetka-Kambal’nyi-Koshelevskii region. An assemblage of newly formed kaolinite, smectite, pyrite, marcasite, and, sometimes, opal is specific to mud water pools with pH > 3.5-4.0 At pH > 5, smectite, pyrite, and opal are produced. In the thermal fields of the Pauzhetka-Kambal’nyi-Koshelevskii region, the walls of steam-gas jets that are often flooded with water and dry out are formed by kaolinite, smectite, opal, α-quartz, pyrite, marcasite, and goethite. The walls of steam-gas jets that are not flooded with water for a long time consist of kaolinite, opal, α-quartz, smectite (traces), alunite group minerals, pyrite, and marcasite in close amounts. The heated grounds of the thermal fields of the Pauzhetka-Kambal’nyi-Koshelevskii region are composed of kaolinite, alunite group minerals, opal, and goethite or an assemblage of kaolinite, smectite, opal, pyrite, and marcasite.