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Aeromagnetic Studies of Eastern Lake Superior

2011; American Geophysical Union; Linguagem: Inglês

10.1029/gm010p0095

2328-8779

William J. Hinze, Norbert W. O’Hara, James W. Trow, George B. Secor,

Geophysical and Geoelectrical Methods

A regional aeromagnetic survey was conducted to determine the relatively unknown basement geology and tectonics of eastern Lake Superior and the eastern half of the Northern Peninsula of Michigan. During this survey approximately 6500 miles of flight lines spaced at 6-mile intervals were recorded with a digital recording proton precession magnetometer system. The results of the survey generally support the geological interpretation that the Lake Superior structural basin consists of thick basic volcanics overlain by clastic sediments. This basin extends southward into the Northern Peninsula of Michigan with the basic volcanics of the Keweenaw Peninsula curving southward through Stannard Rock and Grand Island. The Isle Royale fault parallels the general curvature of the Keweenaw Peninsula to the vicinity of Superior Shoal, where it is terminated by a cross fault striking from Ashburton Bay, Ontario, to Big Bay, Michigan. A fault on the north side of Michipicoten Island continues to the southeast toward Gargantua Point and northward, paralleling the shoreline at a distance of 10 to 15 miles. Midway between Michipicoten Island and Pic Bay, this fault turns northwest and continues south of the Slate Islands to the volcanics outcropping on the islands of Nipigon Bay. South of Michipicoten Island the basic volcanics have been uplifted by an east-west-striking fault which may be a continuation or a branch of the Keweenaw fault. On the east side of the basin, south of these basic volcanics, the volcanics appear to be discontinuous, with major volcanic rock areas extending southwest from Mamainse Point and the eastern margin of the Northern Peninsula of Michigan.