New data on ancient volcanic activity near the modern volcano Shiveluch in the northeast of Kamchatka were discovered by members of the laboratory of geochemistry and ore content of alkaline magmatism at the Vernadsky Institute of Geochemistry and Analytical Chemistry. V. I. Vernadsky Institute of Geochemistry and Analytical Chemistry (GEOKhI) RAS. For the first time were found lavas about 1 million years old, associated with subduction of the Pacific plate, which “dips” under the continental plate. The results were published in the journal Volcanology and Seismology.
Contemporary volcanism of northern Kamchatka could be traced only up to the age of 0.3 million years, although the process of subduction of the Pacific plate in this area began about 2 million years ago. In this investigation, we considered volcanic centers of Baidara and Semkorok which were dated by potassium-argon method at 0.7 and 1.3 Ma, respectively. These centers are located directly at the base of the large andesite volcano Shiveluch, which is less than 0.1 Ma old.
Geochemical features of rocks related to subduction processes and melting of crustal matter were found in the lavas of the Baidara and Semkorok mountains. Low concentrations of niobium and tantalum indicate the subduction origin of rock-forming melts. The lavas of the Semkorok and Baidara volcanic centers are characterized by low content of light rare earth elements, which can be explained by the large-scale involvement of sedimentary crustal material in the melting process.
The mineral composition of the volcanic rocks of the studied objects and traces of disequilibrium in the system testify to the existence of large-scale crustal sources of acid composition as early as 1.3 Ma.
The studies were conducted with the financial support of the Russian Ministry of Education and Science.
These new data allow us to deepen our understanding of volcanic processes in Northern Kamchatka and expand the limits of modern volcanic history in this region. They may also help scientists predict possible volcanic events in the future.