Search results
Results From The WOW.Com Content Network
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 ...
Between the two zones is the Missouri Gravity Low, or MGL, a mass of low density granite including the Missouri batholith up to 370 miles long and 60 miles wide, identified in gravity surveys. Igneous activity ended around 1.3 billion years ago, with the intrusion of numerous dikes and sills into newly crystallized rhyolite and granite.
The New Madrid seismic zone (NMSZ), sometimes called the New Madrid fault line (or fault zone or fault system), is a major seismic zone and a prolific source of intraplate earthquakes (earthquakes within a tectonic plate) in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri.
[4]: 9 A north-northeast trending branch of the Midcontinent Rift System separated the Animikie Basin into two distinct segments; the present-day Animikie Group and the Marquette Range Supergroup; [8] the historical name for the Marquette Range Supergroup is the Animikie Series.
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]
Structures of Kansas showing the Nemaha Uplift/Ridge. The Nemaha Ridge (also called the Nemaha Uplift and the Nemaha Anticline [1]) is located in the Central United States.It is a buried structural zone associated with a granite high in the Pre-Cambrian basement that extends from approximately Omaha, Nebraska to Oklahoma City, Oklahoma.
In geology, a rift is a linear zone where the lithosphere is being pulled apart [1] [2] ... The Midcontinent Rift System, a late Precambrian rift in central North ...
Felt over an area of 193,000 square miles (500,000 km 2), with other sources listing the felt area as 300,000 square miles (780,000 km 2) [8] or 95,000 square miles (250,000 km 2), [9] the 1867 earthquake followed the Midcontinent seismic trend: [1] unlike coastal earthquakes in the United States, events in the central and east-central sectors ...