Aeromagnetic interpretation of the Goodnews and Hagemeister Island quadrangles region, southwestern Alaska

Paleozoic rocks on the Alaska Peninsula: A section in <i>The United States Geological Survey in Alaska: Accomplishments during 1978</i>

“…The shape of these anomalies also suggests that the metamorphic rocks do not continue to depth (Griscom, 1978). The gravity data support the geologic and aeromagnetic data.…”

“…North of the Kanektok River the metamorphic belt coincides approximately with a broad linear magnetic high, the source of which cannot be the metamorphic belt because it extends across the Cretaceous sedimentary rocks as well. The source of the anomaly is a body of magnetic rock concealed at a depth of 1 to 2 km below the surface (Griscom, 1978). The depth to the magnetic rock decreases northeastward, and the rock that causes the anomaly apparently crops out at Greenstone Ridge.…”

“…Interpretation (Griscom, 1978) of the aeromagnetic data (Alaska Division of Geological and Geophysical Surveys, 1973a, b;Dempsey and others, 1957) also suggests that the complex is thin and rootless. North of the Kanektok River the metamorphic belt coincides approximately with a broad linear magnetic high, the source of which cannot be the metamorphic belt because it extends across the Cretaceous sedimentary rocks as well.…”

New potassium-argon data on the age of mineralization and metamorphism in the Willow Creek mining district, southern Talkeetna Mountains, Alaska

“…New paleontological data and numerous radiometric age dates have established the absolute and relative ages of the rocks with more certainty. The map has also benefited from interpretation of aeromagnetic data (Griscom, 1978) that has supported, confirmed, and extended geologic interpretations.…”

Precambrian rocks of Alaska

“…The terrane is composed of crystalline schists and gneisses believed to have been derived by metamorphism of an interbedded sequence of sedimentary and volcanic rocks and associated mafic and felsic intrusive rocks (Hoare and others, 1974). Field relations and aeromagnetic data suggest that the metamorphic terrane is allochthonous and has the form of a thin, rootless slice (J. M. Hoare, oral commun., 1978;Griscom, 1978); the Kilbuck terrane evidently contains rocks that are older than other known areas of Precambrian rocks in Alaska. The Kilbuck is an exotic terrane whose original location has not been established: it was emplaced at its present position in pre-Early Cretaceous time because it is overlain by Lower Cretaceous conglomerate that contains clasts of metamorphic rocks derived from the terrane (Hoare and others, 1974).…”