The reports, introduced on scientific session of the First International Kuril-Kamchatka field workshop, are published in this book. Papers are devoted to studying the geothermal and mineral resources of modern volcanism areas and, first of all, to researching the long-living ore-forming hydrothermal-magmatic systems of insular arcs. The following scientific themes in six sections are submited: (1) geothermal resources, common problems; (2) structure, thermal and power supply of hydrothermal-magmatic systems; (3) petrology, mineralogy and geochemistry of rocks; (4) geochemistry and dynamics of gases and natural waters; (5) ore mineralization in geothermal systems; (6) seismicity of geothermal regions and geotechnological aspects. The tendencies of development of researches, the new ideas and concrete actual materials on an example of geothermal fields of Kuril Islands and Kamchatka, and also New Zealand, Philippines, USA etc., are discussed. The new tasks of geothermal and mineral resources studying are formulated.

Trace element data for volcanic rocks of the Payalpan volcano-tectonic structure (Sredinny ridge, Kamchatka) allows distinguishing typical island-arc, rift and transitional series of rocks. Island-arc basaltic and differentiated magmas erupted in the Late Miocene and Pliocene. In the Late Pliocene – Early Pleistocene, there was a voluminous event dominated by the basaltic magmas of rift-type series. This event followed by voluminous eruptions of mainly basaltic andesites of transitional series. At the end of the Pleistocene and probably during the Holocene volume of eruptions diminished and composition of magmas shifted towards rift-type basaltic series. Practically in the same area in the Pleistocene and Holocene the Icha volcano produced basaltic andesite to rhyolite magmas of the island-arc and transitional series. Reasons for spatial overlapping and temporal evolution of the island-arc and rift magma types are also discussed.