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North America's continents, historical maps, North America spoken languages, physical map and satellite images. Tectonic evolution. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and also the northwestern part of Scotland, known as the Hebridean Terrane. It contains some of the oldest rocks on the Earth, its interior has been stable for the longest period of time, and it was the first continent to achieve approximately its present size and shape. About 1.85 billion years ago the Superior province collided with the southern Churchill province to form the bowlike Trans-Hudson orogenic belt, the crest of which underlies Hudson Bay. Between these three provinces is the sprawling Churchill province—which may be a composite of four or more individual fragments named the Wyoming, Hearne, Rae, and Burwell subprovinces. In addition, a similar uranium-lead technique revealed that the Acasta gneisses, which occur southeast of Great Bear Lake in the northwestern corner of the shield, were at least 3.8 billion (and possibly up to 3.96 billion) years old. Tectonic evolution of South America during the Late Proterozoic. In any given region, relatively thin primeval oceanic crust evolved into thick continental crust over a period of about 50 million years. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Info. The east-side of the North American Plate straddles the Eurasian Plate and African Plate.This is the Mid-Atlantic Ridge where divergent tectonic plates pull apart from each other. The Nain province had already collided obliquely with the eastern Churchill province about 1.82 billion years ago, forming the Torngat Mountains, which parallel the coast of northern Labrador. This event, called the Mazatzal orogeny, may be related to a collision between ancestral North America and an unknown continent to the south, and it concluded the main accretionary stage of North America. While the North American plate in the east moves in the southwest direction, the Pacific plate in the west moves northwest. Geological Survey of Canada, Ottawa, Ontario K1A 0E4, Canada. Geological Formation of North America Through the Eons / Orogeny 600 Million Years Ago To Present. The Rae province includes northern, southwestern, and southeastern prongs. She wrote two major research papers outlining the history of plate tectonic evolution of North America and tectonic problems of the San Andreas Fault , which assisted in documenting the history of the San Andreas Fault Line. Similar deposits of like age are found on other continents, and they form the principle source of iron ore today. 1). The oldest rocks in the world occur in the Canadian Shield. The compositional range of the old rocks is essentially the same as that of much younger rocks, implying similar processes of formation. These rocks are estimated to be 4.28 billion years old. Hundreds of granitic and subordinate basaltic magma bodies were emplaced in a broad zone from southeastern California to the coast of Labrador about 1.6 to 1.3 billion years ago. Watch later. Early Proterozoic rifting and subsequent collisional deformation govern the dimensions of the provinces. "Plate tectonic history of the northeast Pacific and western North America", The Eastern Pacific Ocean and Hawaii, E. L. Winterer, Donald M. Hussong, Robert W. Decker. By continuing to use our website, you are agreeing to our, American Association of Petroleum Geologists, Cushman Foundation for Foraminiferal Research, Mineralogical Society of Great Britain and Ireland. The Rocky Mountains took shape during a period of intense plate tectonic activity that formed much of the rugged landscape of the western United States, starting with the Cretaceous - Paleogene Laramide orogeny, about 70-40 million years ago is responsible for raising the Rocky Mountains. The Geology of North America - An Overview. Copy link. Because it is difficult to track the drift of continental fragments of such antiquity, it is not known how many parent continents are represented by the fragments now located in North America. 1-15. Tanya Atwater, 1970. Western North America is a patchwork is hundreds of terranes, which are crustal pieces or microplates (think of islands), that collided with and attached to North America across hundreds of millions of years -- adding piece-by-piece to the continent's width and building mountains as they produced volcanoes or pushed up sediments and rocks.This posts provides a very simplified timeline … Following continental separation, sediments accumulated on subsiding continental shelves. Paul F. Hoffman, 1989. This craton, known as Laurentia, included Greenland and northwest Scotland until their partial separation in the Late Cretaceous. Early history of the Earth ... Mountains and basins of western North America and Central The largest of these fragments forms the Superior province, which is located in the south-central part of the Canadian Shield and is some 1,500 miles (2,400 km) wide. The process of continental breakup began about 2.45 billion years ago along the southern margin of the Superior province, producing extensive sets of parallel dikes (vertical sheets of crystallized intrusive magma) and rift valleys containing lavas with chemical compositions characteristic of plates undergoing horizontal stretching. The "Tectonic Map of North America," on a scale of 1: 5,000,000, has been compiled by the United States Geologi­ cal Survey in collaboration with other national geological sur­ veys, and with the assistance of various individuals. Compare and contrast Precambrian and Phanerozoic tectonic processes as preserved in the rock record of North America. Heat buildup beneath the stationary supercontinent induced a large-scale upwelling from the mantle that ultimately contributed to supercontinental breakup. Striking similarities between contemporaneous shelf sediments on the southern margins of the Wyoming and Superior provinces and between the crust of the Superior and Hearne provinces, however, suggest that they originally may have been juxtaposed. This is because tectonic plates collide and sink at these zones of subduction (convergent plate boundaries). Rocks in the Minnesota River valley, near the southern limit of the shield southwest of Lake Superior, range in age up to 3.66 billion years. Over time, collisions with the different subduction zones smeared exotic terranes along the continent's western margin, a rock record that has long hinted at North America's violent tectonic history. Thus, what is now the stable interior of the continent was, about 1.85 billion years ago, laced with great mountain ranges. They were accreted piecemeal to the protocontinent to the north and then subjected to regional northwest-southeast compression between about 1.7 and 1.6 billion years ago. Over 1 billion years ago proto-North America, collided with another continent. The core of the North American continent (Canadian shield) came together in the Paleoproterozoic (2.0–1.8 Ga) by plate collisions of Archean continents (Slave with Rae-Hearne, then Rae-Hearne with Superior) as well as smaller Archean continental fragments (Wyoming, Medicine Hat, … The Phanerozoic history of North America, when viewed from the perspective of Pangea, can be divided into three broad phases with gradational time boundaries, as described in the following paragraphs.. During the first phase, which lasted from the late Precambrian to the Pennsylvanian, Pangea was under construction and the North American craton was marked by various, persistent, … Navigate parenthood with the help of the Raising Curious Learners podcast. Each province is a Late Archean crustal aggregate and contains variable proportions of Early and/or Middle Archean crust. (The shelf sediments, deposited about 2.4 billion years ago, are particularly significant in that they contain discrete layers strewn with boulders dropped from shelf ice, implying that seawater then had a temperature range similar to that of the present.) The magmatism was most profuse in the new crust of the southern interior platform, which was blanketed by up to 4 miles (6 km) of volcanic ash flows derived from the partial melting of the lower crust. Precambrian bedrock of the Canadian Shield rising out of Reindeer Lake, on the border between northeastern Saskatchewan and northwestern Manitoba. The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. As the thickened crust emerged above sea level, it was stripped by erosion and redeposited in adjacent depressions as detrital sediment. Volcanic island arcs were accreted to the western margin of the Slave province, forming the Wopmay Orogen; to the southern margin of the Superior province, forming the Penokean Orogen; and to the southeastern margin of the Nain province, forming the Ketilidian Orogen. Print. The interval between about 3.0 and 2.6 billion years ago was one of rapid crustal growth in North America, during which most of the Canadian Shield and the crust beneath the northern Great Plains was formed. The central core of present-day North America is its craton, the oldest, thickest part of the continent. Radiogenic isotopic data from the Precambrian shield, and from inliers and subsurface samples on the platform indicate that about 55 percent of the area of the craton separated from the mantle in the Archean and about 45 percent in the Proterozoic (Fig. This animation shows the plate tectonic and paleogeographic evolution of the South America from 160 million years ago to the present-day. Whereas South America and Africa were not assembled until 0.7 Ga, and the assembly of Eurasia began at 0.3 Ga, most of the North American craton has been coherent since 1.7 Ga. North American Plate Movement. The formation of the Boston area started with the Greenville Mountains. There are many occurrences of rocks between 3.5 and 3.0 billion years old, but, like the older rocks, none are known to be more than a few tens of square miles in extent. Benjamin Bley de Brito Neves, Umberto G. Cordani 1991. The external margins of the composite protocontinent also were active between 1.9 and 1.8 billion years ago. The colonial architecture of the United States and Canada was as diverse as the peoples who settled there: English, Dutch, French, Swedish,... A rock formation called “faux amphibolite,” from the Nuvvuagittuq greenstone belt in northern Quebec, dated to 4.28 billion years ago. The geology of Alaska is typical of that of the cordillera. Includes the breakup and piecewise subduction of the Farallon plate and the consequent development of the San Andreas plate boundary. While parts of the craton peek out in Greenland and Canada, in the U.S., thick layers of sedimentary rocks keep most of these ancient assemblages under wraps in the center of the continent. Consequently, the Churchill province experienced much more magmatism, metamorphism, and deformation in this interval than did the Slave, Superior, or Nain provinces. To the south a series of localized basins developed in what is now the Rocky Mountains. In the present configuration of tectonic plates, the northeast Pacific region is dominated by the huge Pacific Plate. (A similar style of magmatism occurred from 300 to 150 million years ago in new crust near the active southern margin of the supercontinent Pangaea. North America is an ancient continent in several respects. Geologic and Tectonic Development of the North America-Caribbean Plate Boundary in Hispaniola (SPECIAL PAPER (GEOLOGICAL SOCIETY OF AMERICA)) Har/Map Edition by Paul Mann (Author), Grenville Draper (Author), John F. Lewis (Editor) & ISBN-13: 978-0813722627. The continental fragments constituting interior North America coalesced between about 2.0 and 1.8 billion years ago. The zonation of the Trans-Hudson belt is typical of collision zones: granitic rocks representing the eroded roots of a continental volcanic arc occur along the Churchill province margin, the medial zone comprises relics of oceanic island arcs, and the Superior province margin is characterized by shelf sediments overthrust by slivers of oceanic crust. It includes the Cascades, Sierra Nevada, and Basin and Range province; the Rocky Mountains are sometimes excluded from the cordillera proper, in spite of their tectonic history. The history revealed by the mantle slabs helps explain some baffling geology, such as rocks carried 1,200 miles (2,000 km) from Mexico to Canada. The Juan de Fuca Plate is still actively subducting beneath N. America. As exposed in the Canadian Shield, the thickened crust consists of many varieties of granitic intrusions separated by belts of folded and faulted volcanic and sedimentary rocks. The second occurred about 600 million years ago, when fragmentation of ancestral North America created the continental margins along which the peripheral orogenic belts developed. Includes tables of contents for the other volumes in this series. Review the growth of the North American continent as a consequence of tectonic accretion. It contains some of the oldest rocks on the Earth, its interior has been stable for the longest period of time, and it was the first continent to achieve approximately its present size and shape. 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