COMPARISON OF NEOGENE-QUATERNARY VOLCANISM ON SAKHALIN AND IN THE EAST SIKHOTE ALIN: 1. LATE CENOZOIC VOLCANIC ROCKS OF SAKHALIN

Abstract

The Late Cenozoic volcanic rocks of the East Sikhote Alin are believed to be Pliocene-Quaternary formations by most investigators, even though there is evidence that volcanic activity there began as early as the late Miocene. Volcanic activity consisted of continental fissure eruptions which changed to summit crater events at some volcanoes during the late periods of the volcanic history. The consequence of the latter was the formation of viscous lava domes and alkaline basalt lava flows. The products of the fissure eruptions were basalts and basaltic andesites of the tholeiitic and alkaline basalt series, similar to rocks from Cenozoic backarc regions in the silica content.