Formation sequence of igneous and sedimentary rocks of the islands of the central part of the Peter the Great Bay (the Sea of Japan)

Abstract

The article presents the results of geological works performed on the islands of the central part of the Peter the Great Bay in the period from 2003 to 2016. It is established that these islands have a similar geological structure. They are composed of typical complexes of sedimentary and magmatic rocks of different ages – from the Late Paleozoic (early to late Permian) to the Middle-Late Jurassic. The oldest rocks are Early Permian sedimentary formations of the Pospelovskaya Suite (Russky Island), and the youngest are the pink leucocratic granite-porphyry of the island complex of the Middle-Late Jurassic age. The geological structure of the studied islands is specified. Types of igneous and sedimentary rocks not described here earlier were found on some of the islands. New data on radioisotope ages for magmatic and paleontological determinations for sedimentary rocks are given. A new age sequence is proposed for the formation of different types of rocks on the islands of the central part of the Peter the Great Bay. Two stages of geological development of the investigated region are distinguished: 1 – Late Paleozoic (Permian); 2 – Early Mesozoic (Triassic).