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Summary: 1
POTASSIC MAGMATISM ON ST. LAWRENCE ISLAND,
ALASKA, AND CAPE DEZHNEV, NORTHEAST RUSSIA:
EVIDENCE FOR EARLY CRETACEOUS SUBDUCTION
IN THE BERING STRAIT REGION
Jeffrey M. Amato,1 Elizabeth L. Miller,2 Andrew T. Calvert,3 Jaime Toro,4 and James E. Wright5
INTRODUCTION
St. Lawrence Island is the largest island on the Bering
Shelf between Russia andAlaska and was the subject of
reconnaissance investigations by the U.S.Geological
Survey in the late 1960s and early 1970s (Patton and
Csejtey, 1971; Csejtey and Patton, 1974). St. Lawrence
Island is about 160 km long and contains exposures of
Paleozoic sedimentary rocks, Permian(?) to Triassic
gabbroic rocks, Cretaceous plutonic and volcanic rocks,
and Quaternary basalt flows. This paper reports
structural, geochemical, and geochronologic data from
Cretaceous volcanic and plutonic rocks on St. Lawrence
Island, as well as geochemical and geochronologic data
from a syenite pluton at Cape Dezhnev on the Chukotka
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