stripes
This volcanic area is represented by lava flows which are about 10 km long and up to 60 m thick; they fill a present day valley. As a rule the lavas are massive but the upper parts are typically scoriaceous in places. They include nepheline basalt (basanite), analcime basalt and limburgite of which the nepheline basalt contains olivine and occasionally aegirine-augite and titanaugite. The content of nepheline varies between 5 and 10% and is present in the form of micro-poikilitic crystals. A little K-feldspar is occasionally present. Phenocrysts of aegirine-augite and olivine (30%) have been recorded in the limburgires in which augite, olivine and volcanic glass form the groundmass.
BELYI, V.F. and MIGOVICH, I.M. 1971. Neogene-Quaternary volcanic formations in the East Chukotka and Lower Penzhina. In Petrology of Neogene-Quaternary basaltoids in the North-West sector of the Pacific Mobile Belt. 114-25. Nauka, Moscow.
RABKIN, M.I., 1954. Alkali basic and ultrabasic effusive rocks in the southern part of the Chukotka Peninsula. Proceedings of Scientific Research Institute of Arctic Geology, 43: 57-65.