Magnetic susceptibilities of crystalline rock samples, Yukon River-Porcupine River area, east-central Alaska

Paleozoic, Mesozoic and Tertiary granitic rocks and Precambrian to Cenozoic mafic volcanic rocks crop out along the margins of the Yukon Flats and Porcupine Plateau. Profiles from airborne magnetometer surveys show that magnetic anomalies occur above the outcrops of many of these rocks. Similar magnetic anomalies also occur above the mantle of surficial deposits in the Yukon Flats, leading to the interpretation that a large part of the Flats is underlain at shallow depth by volcanic rocks and possibly also by granitic rocks (Andreasen, 1960; Zietz and others, 1960; Brosge and others, 1970). To aid in further interpretation of these magnetic anomalies, the available data on magnetic susceptibilities of igneous and metamorphic rocks in the area around the Flats are reported below (Table