The first continuous late Pleistocene tephra record from Kamchatka Peninsula (NW Pacific) and its volcanological and paleogeographic implications

The Kamchatka volcanic arc (NW Pacific) is one of the most productive arcs in the world, known for its highly explosive activity. At the same time, the Kamchatkan record of late Pleistocene explosive eruptions has remained fragmentary. Here we present the first continuous record of Kamchatkan explosive activity between ~12 and 30 ka, which includes ~70 eruptions and extends the earlier reconstructed Holocene sequence for another 20 ka. Our record is based on geochemical correlations of 14C-dated tephras that represent all Kamchatka volcanic zones and are buried in lacustrine deposits along the 200 km stretch of the Central Kamchatka Depression (CKD). The accompanying geochemical database of volcanic glass compositions includes 3104 new electron microprobe and 221 LA-ICP-MS analyses. The data show that during the period under study, large silicic explosive eruptions peaked at 30e25 ka. Later times were mostly associated with the moderate activity from northern CKD volcanoes Shiveluch and Zarechny. Our tephra record provides the first tephrochronological model for dating and correlating Central Kamchatka late Pleistocene deposits and gives us some insight into the timing of glacial advances in the Kliuchevskoi volcanic group and volcanic response to the onset of the Last Glacial Maximum and glacial unloading at its termination. In addition, studied sections of lacustrine deposits tightly linked by tephra markers suggest the existence of a large lake system within the CKD for ~20 kyr until its final discharge at ~12 ka BP