The Geysernaya River Alluvium (Kamchatka): Composition and Features of Formation

A comprehensive analysis of the composition of the alluvium of the river with active gas–hydrothermal occurrences has been carried out for the first time. Common features in the lower and middle reaches of the Geysernaya River include poor roundness of boulders and pebbles (grades 1–2), poor grading of alluvium fine-clastic components, abundant rock fragments, and mineral intergrowths even in the fine-sand fraction. All this information is indicative of weak sediment disintegration and a high proportion of slope material in sediments, including that redeposited by mudflows. High contents of smectite–zeolite and other newly formed (secondary) mineral aggregates (up to 70