Description

From Wood and Kienle (1990) ^[1] : "The Kookooligit volcanic field, on northern St. Lawrence Island, is one of a number of basalt fields in the Bering Sea region. The field consists of an elongate shield volcano over 500 m high composed of massive columnar-jointed basalt flows overlain by >100 small cones (20 to 60 m high) aligned east-west along a volcanic highlands. The older volcanic flows are chiefly alkali olivine basalts and olivine tholeiite. The younger cones and flows are dominantly basanite and alkali olivine basalt with subordinate hawaiite and nephelanite. Most of the basanite and nephelanite flows and cones contain inclusions of deformed periodotite or gabbro; some also contain megacrysts of anorthoclase.
"Most of the young volcanic rocks have primitive whole-rock compositions characterized by high MgO and low SiO2 contents. The suite is characterized by decreasing total alkalies with increasing SiO2, similar to the trend observed in Hawaiian lavas."