Vetrovoy isthmus of iturup island – holocene strait

Abstract

Abstract Explosive volcanism is equally important as the features of neotectonic and modern movements for the development of the Kurile Islands coast, as it led to the afflux of hundreds of millions of cubic meters of pumisopyroclastic material and tephra into the wave processing zone of coastal zones of the Pleistocene-Holocene. Morphometric, georadar and paleogeographic studies of the coastal-sea relief of Iturup Island allowed to determine several levels of marine terraces in the pyroclastic sediments of the Late Pleistocene-Holocene, and also the presence of a buried sea strait that existed at least in the middle Holocene. Taking into account the values of deformation of the terrace levels, the depth of the strait was 10-15 meters. Volcanic-tectonic deformations connected with eruptions near the central part of the Vetrovoy Isthmus led to the collapse of pumice packs at the section basement of the sea coastal ledge with a layer of beach material on the roof (LU-9223-6320 ± 100, cal. Year BP). Thus, in the mid-late Holocene, after the sea level was risen to the nowadays levels, at least two more pyroclastic series were deposited, the last of which one is dated 1050 ± 70 cal. BP – LU-8685.