| Title | Evolution of the Pauzhetsky Geothermal Area and Acid Volcanism |
|---|---|
| Authors | Vladimir BELOUSOV, Irina BELOUSOVA, Olga KHUBAEVA |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | geothermal region, acid volcanism, evolution, long-lived volcanic centers, extrusion, pumice, ignimbrite, magma chamber, basalt, andesite, rhyolite, dacite, volcanoes |
| Abstract | In the Pauzhetsky geothermal area, the development of the Earth's crust from the Pliocene to the present has been determined by long-lived volcanic centers in the mode of the island arc which was the northern extension of the Kuriles. Near their boundaries, facial transitions from basaltic lavas and pyroclastic rocks to coarse sediments are observed, which at a distance are replaced by increasingly shallow volcanomictic material. From the Upper Pliocene to the Middle Pleistocene, the area of distribution of the effusive basalt composition of the long-lived volcanic centers is sharply increased. A significant number of eruption channels are produced, through which lava and pyroclastics of various compositions were erupted, including ignimbrites, pumice and lava flows and andesite, dacite and rhyolite domes. Acid rocks are the products of magma chambers activity in the Earth's crust. This period is characterized by the expansion of the land area due to the appearance of central-type volcanoes with calderas in the conditions of a glacier of considerable thickness (hundreds of meters and first kilometers). In the Holocene, the number of eruption channels on the Ilyinsky and Zheltovsky long-lived volcanic centers is reduced to one and these volcanoes were transformed into central-type volcanoes. Koshelevsky, Kambalny and Dikii Greben Ridge long-lived volcanic centers have a linear-nested arrangement of eruption channels, the same as on the Vernadsky Ridge (Paramushir Island, the Kuril volcanic arc). It is assumed that such volcanic ranges inherit basaltic fissure structures similar to the fissure eruptions of Iceland and Hawaii. Acid magma chambers screened heat flows of the mantle basalt reservoirs, partially generated and retained heat which feeds the hydrothermal systems of the Pauzhetsky geothermal area, and increased the thickness of the granite layer of the Earth's crust. The granitization process led to the formation of the geological structure of the continental type in the southern tip of the Kamchatka Peninsula. |