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@article{osti_6431485, title = {Organic Geochemical and tectonic evolution of the Midcontinent Rift system}, author = {Hayes, J M and Pratt, L M and Knoll, A H}, abstractNote = {The older assemblages stand in contrast with the ca. 1000 Ma old Hunting Formation, Arctic Canada, which contains what may be the oldest evidence for modem algae - red algal fossils that compare closely with members of ...The Midcontinent Rift System (MRS) of North America represents a major thermal-tectonic rifting event ca. 1.1 Ga marked by a huge volume of igneous rock emplaced in a relatively short time span of ~30 million years, followed by deposition of a thick package of clastic sediments with subsequent faulting (Wold and Hinze, 1982).Magmatic Ni-Cu-PGE mineralization in the ~ 1.1 Ga Midcontinent Rift System (Fig. 1) in North America can be broadly divided into three types (see a recent review by Ripley, 2014). Disseminated sulfide mineralization occurs within multiple, sheet-like intrusions that comprise a large portion of the Duluth Complex.The Midcontinent Rift System (MRS) (sometimes referred to as the Central North American Rift System or Midcontinent Gravity High) has long been recognized from geophysical mapping to trend south-southwestward from Lake Superior into central Kansas in a snake-like curving pattern. Faults of this zone trend north-northeast-southsouthwest …The Midcontinent Rift System (MRS; Wold and Hinze, 1982) is recognized by a significant elongate magnetic and gravity anomaly extending northeastward from south-central Kansas into the Lake Superior region and hence southeastward into the Michigan basin (Figure 45). Van Schmus and Hinze (1985) and Dickas (1984, 1986) provide excellent overviews ...The Middle Proterozoic Midcontinent Rift System (MRS) of North America is a failed rift that formed in response to region-wide stresses about 1,100 Ma. In Iowa, the MRS is buried beneath 2,200?3,500 ft of Paleozoic and Mesozoic sedimentary rocks and Quaternary glaciogenic deposits. An extremely large volume of sediments was deposited within basins associated with the rift at several stages ...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 … See moreProminent examples of rift failure include the North Sea, the West African Rift System and the Midcontinent Rift underlying the Great Lakes of North America. Rifting stopped in these cases because ...The Middle Proterozoic Midcontinent Rift System (MRS) of North America is a failed rift that formed in response to region-wide stresses about 1,100 Ma. In Iowa, the MRS is buried beneath 2,200?3,500 ft of Paleozoic and Mesozoic sedimentary rocks and Quaternary glaciogenic deposits. An extremely large volume of sediments was deposited within basins associated with the rift at several stages during26 Oca 2014 ... A billion years ago, North America was trying to split apart, just as East Africa is today. The split, called the mid-continent rift system, ...The Mesoproterozoic Midcontinent Rift System (MRS) of North America hosts a diverse suite of magmatic and hydrothermal mineral deposits in the Lake …THE MIDCONTINENT RIFT SYSTEM. Annual Review of Earth and Planetary Sciences Vol. 13:345-383 (Volume publication date May ... Figure 3: Relationships between key components of the CO2 system as a function of the master variables, alkalinity and dissolved inorganic carbon (DIC). CO2 contours show the atmospheric CO2 concentra...Geophysical investigations have had a prominent role in studying the 1100 Ma Midcontinent Rift system because of limited surface exposures and deep drilling of the rift rocks. Gravity and magnetic anomaly data delineate the rift system—its central volcanic-filled graben and overlying and adjacent post-rift sedimentary basins—and the major ...

The Mesoproterozoic Midcontinent Rift System (MRS) of North America hosts a diverse suite of magmatic and hydrothermal mineral deposits in the Lake …We test this algorithm on the Proterozoic Midcontinent Rift (MCR), north-central United States. The MCR provides a challenge because it hosts a gravity high overlying low shear-wave velocity crust in a generally flat region. Our initial density estimates are derived from a seismic velocity/crustal thickness model based on joint inversion of ...The Midcontinent Rift System (MRS) is an example of a mafic-dominated continental rift where silicic magmatism is locally significant. The best-preserved example of this is on the NE limb of the rift along the North Shore of Lake Superior where rhyolites comprise a large percentage (up to 25%; Green, J.C., Fitz, T.J., III, 1993. Extensive felsic lavas and rheoignimbrites in the Keweenawan ...In the United States, the Duluth Complex in Minnesota, comprised of a group of mafic intrusions related to the 1.1 Ga Midcontinent Rift system, represents a major Ni resource of 8 Mt Ni, but deposits generally exhibit low grades (0.2 percent Ni, 0.66 percent Cu) and remain in the process of being proven economic.

The Keweenaw Fault (KF) has been interpreted as a -bounding normal fault along the rift southern margin of the southwest arm of t he Midcontinent Rift System (MRS) , which was later inverted into a reverse fault by a tectonic compression event (Cannon, 1994; Hinze and Braile, 1990).The Midcontinent Rift of North America is a ca. 1.1 Ga, 3000-km-long failed rift that nearly split the Precambrian continent of Laurentia. Unlike most continental rifts, which are filled with a mixture of volcanic rocks and sediments, the Midcontinent Rift contains a large volume of flood basalts that were emplaced during both syn- and post-rift stages.…

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs. The Mid-Continent rift system can be traced by the Mid-Co. Possible cause: Called the Midcontinent Rift System (MCRS), this structure is a 1.1 billion-year.