...James M. DeGraff; Brad T. Carter Abstract The Keweenaw fault system along Lake Superior’s south shore in Michigan, USA is one of the most significant fault systems associated with North America’s Midcontinent Rift System. Reverse slip has thrust Portage Lake Volcanics (ca. 1.1 Ga) southeastward...

...Figure 3. Field relationships of Keweenaw fault vein calcite and U-Pb geochronology. (A) Outcrop of vein calcite within brecciated Portage Lake volcanic host rock in the Keweenaw fault zone. (B) Vein calcite sampled as LLB6 with slickensides indicated by white arrows. (C) Sample LLB2 vein calcite...

...CHARLES T. YOUNG; TED R. REPASKY Abstract Eight magnetotelluric soundings were conducted across a basin of the Jacobsville Sandstone along a northwest-southeast line, beginning north of Toivola, Michigan, northwest of the Keweenaw fault and ending near the village of Keweenaw Bay in Michigan's...

.... The Douglas, Isle Royale, and Keweenaw fault zones, clearly imaged on the seismic profiles, are interpreted to be large offset detachment faults associated with initial rifting. These faults have been reactivated as reverse faults with 3–5 km of throw. The Douglas Fault Zone is not directly connected...

...John Mariano; William J. Hinze Abstract Integrated interpretations of potential-field and GLIMPCE and industry seismic reflection data in eastern Lake Superior reveal the structural and stratigraphic complexity of the Midcontinent Rift in this region. Projection of the Keweenaw fault...

... into a narrow segment of Portage Lake strata may be attributed to upward thrusting on the Keweenaw fault during closure of the Midcontinent rift, forming anomalously hot, steeply dipping aquifers on the Keweenaw promontory, and to the development of a single, dominant thermal plume within the incipiently...

...-depositional structural features such as the Lake Superior syncline and the Keweenaw fault as well as the present Lake Superior basin also parallel basement structural trends. It is concluded that resurgent tectonics have been active in the Lake Superior region since pre-Keweenawan time and have exerted...

... the Baltic, or lower, to the Great conglomerate, and that the Keweenaw fault is cutting higher into the series to the southwestward, eliminating some of the lower horizons. GeoRef, Copyright 2006, American Geological Institute. Abstract, Copyright, Society of Economic Geologists. Reference includes data...

... be traced uninterrupted across most of the rift basin, which is bounded to the north by a complex region of secondary sagging, felsic volcanism, and (or) intrusives, and to the south by the Keweenaw fault. The crust–mantle transition zone is characterized by both a smooth amplitude anomaly...

... such as the Lake Superior syncline and the Keweenaw fault, as well as the present Lake Superior basin, also parallel basement structural trends. It is concluded that resurgent tectonics have been active in the Lake Superior region since pre-Keweenawan time and have exerted a significant effect upon the area...

..., <10°, except locally in areas of structural disturbance such as in the vicinity of the Keweenaw fault ( Kalliokoski, 1982 ). In the Upper Peninsula of Michigan (figure 3A of Malone et al.), the JS unconformably overlies older Mesoproterozoic to Archean rocks on the eastern and southern edges...