Age and Composition of Igneous Rocks from the Cenozoic Sedimentary Cover of the Sakhalin Shelf

The K–Ar isotope age and petrological–geochemical data were obtained for the first time on igneous rocks from a core recovered from previously drilled wells on the Sakhalin shelf. Based on these data, the igneous rocks were compared to the rocks of the Anivskiy, Orlovskiy, Lamanonskiy, and Chekhovskiy volcanic complexes. The isotopic ages obtained on rocks from the Lesogorskiy Complex of hypabyssal small intrusions exposed on the western coast of Sakhalin Island allowed tighter constraints to be placed on the timing of its formation (8.9–16.2 Ma).