volcanogenic

Volcanogenic is an adjective used in geology and related fields to describe rocks, sediments, structures, or processes that originate from volcanic activity. It covers both direct volcanic products and secondary effects of volcanism, including materials deposited or formed as a result of eruptions and associated hydrothermal systems.

Volcanogenic sediments and rocks arise from volcanic ejecta such as ash fall, pumice, and volcanic lapilli. When fragmented volcanic material is deposited and lithified, it forms volcanogenic sedimentary rocks, including tephra deposits, tuffs, and ignimbrites. Volcaniclastics are a broader category that includes any clastic rocks derived from volcanic material, including reworked ash and volcanic debris.

Volcanogenic ore deposits are a prominent use of the term in economic geology. Volcanogenic massive sulfide deposits form on or near the seafloor in volcanic settings, typically at mid-ocean ridges or island arcs, through the circulation of hydrothermal fluids that leach metals from the crust and precipitate sulfides when they mix with seawater. These deposits commonly contain copper, zinc, and lead sulfides, often with iron, and may host gold and silver.

The term is sometimes contrasted with lithogenic or volcaniclastic, and its specific meaning can vary by discipline. In sedimentology and ore geology, volcanogenic indicates a volcanic influence on the origin or composition of materials, while volcaniclastic emphasizes the fragmental, volcanic-derived character of the material.