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The Midcontinent Rift System (MRS) or Keweenawan Rift is a 2,000 km (1,200 mi) long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the continent's core, the North American craton , began to split apart during the Mesoproterozoic era of the Precambrian , about 1.1 ...
[4]: 7 This zone of crustal thinning and fracturing is the Midcontinent Rift System; it extends in a boomerang shape for over 2,200 km (1,400 mi) from northeastern Kansas northward through Iowa, under the Twin Cities of Minnesota, beneath Lake Superior, and then south through the eastern Upper Peninsula of Michigan and beneath the central Lower ...
The Keweenawan Supergroup is a supergroup of volcanic and sedimentary rocks that fill the Midcontinent Rift System in the U.S. states of Michigan, Wisconsin, and Minnesota. [1] [2] It is about 30 kilometers (19 mi) thick and it formed about 1.1 billion years ago. [3]
The fault thrusts lava flows of the Midcontinent Rift System onto sedimentary rocks of the Jacobsville Sandstone. The fault is part of the inversion of the Midcontinent Rift where a region that had previously undergone extension experienced significant contraction. This contraction occurred during the final stages of the Grenvillian orogeny. [2]
(The ridge also has a secondary rift valley running its length.) The width is an average taken along the spreading ridges (Georgia–Senegal, Brazil – Bight of Benin, etc.). The greatest depth is the Romanche Trench. (The Puerto Rico Trench is not part of the rift system.) Great Rift Valley: 6,000 km (3,700 mi) 220 km (140 mi) 2 km (1 mi)
Midcontinent Rift System; N. Nipigon Embayment; P. Purus Arch; S. Lake Superior; W. White Sea Rift System This page was last edited on 2 November 2023, at 23:13 ...
Shaded-relief image showing the Duluth Complex arcing from Duluth to Pigeon Point, interrupting and splitting the Mesabi and Gunflint Ranges. The Duluth Complex, the related Beaver Bay Complex, [1] and the associated North Shore Volcanic Group are rock formations which comprise much of the basement bedrock of the northeastern part of the U.S. state of Minnesota in central North America.
A slightly younger but possibly related geologic feature is the 2,000 km (1,200 mi) long Midcontinent Rift System adjacent to the southern end of the Mackenzie Large Igneous Province. [4] The Lake Superior portion of the Midcontinent Rift System is bounded on the south by pre-existing continental faults that had substantial right-lateral ...