Pleistocene-Holocene Monogenetic Volcanism at the Malko-Petropavlovsk Zone of Transverse Dislocations on Kamchatka: Geochemical Features and Genesis

The Malko-Petropavlovsk zone of transverse dislocations (MPZ) was formed on the extension deep Avachinsky transform fault in perpendicular relation to subduction trench. It is a natural boundary between variously aged slabs Kamchatka (103–105 Ma under Southern and 87–92 Eastern volcanic belt). Monogenetic cinder cones MPZ are randomly distributed along these long-lived rupture zones. Here we present new geochemical isotopic results monogenetic volcanism MPZ. Based whole rock trace element geochemistry, Pb-Sr-Nd ratios cone magmas were shown tap enriched mantle source (low 143Nd/144Nd (0.512959–0.512999), changed as 87Sr/86Sr (0.703356–0.703451) 206Pb/204Pb (18.30–18.45), 208Pb/207Pb (38.00–38.12) ratios). High Nb/Yb La/Yb ratios, without significant inputs slab’s components (the lowest Ba, Th content), indicate decompression melting predominately. Calculations pressure (9–11 kbar) temperature (1160–1240 °C) conditions using glass thermobarometer suggest that magma resided near Moho prior eruption. This correlates with crustal discontinuity according geophysical observations (converted-wave seismic exploration magnetotelluric sounding). majority well-preserved Holocene, after last glaciation, but eruptions not observed historically. This, however, suggests similar may occur future. Given hosts major population centres (Petropavlovsk, Elizovo, Vilyuchinks, Paratunka: ~ 250,000 people or 80% Kamchatkan live cities coastline MPZ), highlight urgent need install continuous monitoring system around cones, investigation, more serious attention from local government scientists. In particular, detailed study regarding age, volume, hazard assessment (pyroclastic vs extrusive) will help reduce potential risks volcanoes for humans infrastructures.