Novarupta Lava Dome Convergent boundaries , where two plates are moving toward each other, are of three types, depending on the type of crust present on either side of the boundary oceanic or continental . USGS photo. The fact that the plates include both crustal material and lithospheric mantle material makes it possible for a single plate to be made up of both oceanic and continental crust. A divergent boundary occurs when two tectonic plates move away from each other. What type of plate boundary is the Cocos Plate? Pillow lavas form on the ocean floor where erupting magma encounters cold sea water. Half Dome in Yosemite National Park is made of granite that solidified from magma tens of millions of years ago, when a subduction zone extended along the entire west coast. It is likely that as many as 20 mantle plumes, many of which still exist, were responsible for the initiation of the rifting of Pangea along what is now the mid-Atlantic ridge (see Figure \(\PageIndex{10}\)). The park is a complex amalgamation of blocks of continental and oceanic crust that have slammed into North America. A mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. But parks in the Cascade Mountains within the same subduction zone are dramatically different. The part of the plate around the South America plate is moving northwards and a little east. (Click on arrows and slide left and right to see labels.). The southerly side is a divergent boundary with the Antarctic Plate called the Southeast Indian Ridge (SEIR). North America plate, Africa plate, Australia plate, Arabia plate, India plate, Filipino plate. The part of California west of the San Andreas Fault and all of Baja California are on the Pacific Plate. Now suppose the subduction processes that form the volcanoes were to stop, shutting off the magma supply that feeds the volcanoes. Granite rocks found in national parks in the Sierra Nevada are the cooled and eroded remnants of magma chambers that fed ancient subduction zone volcanoes in California. The North American Plate . This plate is small. As fluid basalt lava flows into the ocean it forms a pile of globular structures known as pillows. The low region between the two parallel mountain ranges is the, 150 miles inland, the top of the subducting plate reaches depths where its hot enough to generate fluids, forming volcanoes in the. Remove unwanted regions from map data QGIS. Many transform boundaries are found on the sea floor, where they connect segments of diverging mid-ocean ridges. Remove the Oregon quarter to reveal cooled magma chamber rocks below. What type of boundary is the Cocos Plate? The plate boundary is a broad zone of deformation with a width of about 60 miles (100 kilometers). Like Mt. Credit: Photo Courtesy of Robert J. Lillie. From 1999 to 2008, the United States Mint issued 25-cent coins representing each of the 50 states. The eastern margins of North and South America and the western margins of Europe and Africa are called passive margins because there is no subduction taking place along them. Volcanic and metamorphic rocks exposed in Kenai Fjords National Park reveal the incredible forces that occur at an ocean/continent subduction zone. Would you characterize earthquake activity as. But the incident highlighted the importance of monitoring volcanic activity and making the information immediately available to the airline industry and other segments of the public. Along much of the boundary, the bulk of the motion occurs along the San Andreas Fault. Subduction in the Pacific Northwest creates incredible beauty in the form of coastlines, mountains, and valleysiconic features of the many National Park Service sites in the region. The roots of ancient mountain belts, which are present along the eastern margin of North America, the western margin of Europe, and the northwestern margin of Africa, show that these land masses once collided with each other to form a mountain chain, possibly as big as the Himalayas. Most of the sedimentary rocks formed from layers of sand and mud deposited in the ocean. The part of the plate around the Australia plate is moving southwards. This plate is bound by the North-American and Caribbean Plates to the north-east, the small Rivera Plate to the north-west, the Pacific Plate to the west, and the Nazca Plate to the south (Fig 1). The types are ocean-ocean, ocean-continent, and continent-continent. Compared to the other tectonic plates in the region, the Cocos Plate is converging with the Caribbean Plate at a steady rate of about 78 millimeters per year based on data from ISCO over 10 months. Later, most of the settlers coming on the Oregon Trail continued past central Oregon and Washington to the lush farmland of the Willamette Valley and Puget Sound, the low-lying region between the two rising mountain ranges. South America plate, Pacific plate, Antarctic plate, Cocos plate. The largest earthquakes occur near the surface where the subducting plate is still cold and strong. Over the next 50 million years, it is likely that there will be full development of the east African rift and creation of new ocean floor. Rainier were to suddenly and violently eruptso much that its magma chamber empties and the volcanic peak collapses in on itself. Mazama, erupted and collapsed 7,700 years ago, forming the large cavity (caldera) that now holds Crater Lake. Plate Boundaries Divergent UU) Transform North American Plate Convergent Other Plate Motion Caribbean Plate Indias Plate motion vectors rotated based on the direction of plate movement Cocos Plate Pacific Plate South American Plate Google Earth Z age Landsat / Copernicus ata SIO, NOAA . Geology This subduction-subduction-transform (SST) triple junction is referred to hereafter as the NACC triple junction. The Coast Range and Cascades are the two parallel mountain ranges that form the Cascadia Subduction Zone in the Pacific Northwest. At transform boundaries lithosphere is neither created nor destroyed. Before we talk about processes at plate boundaries, its important to point out that there are never gaps between plates. Rainier in Mt. Plate Tectonics and Our National ParksSite Index, Plate TectonicsThe Unifying Theory of Geology, Tectonic Settings of NPS SitesMaster List, ORCAOregon Caves National Monument, Oregon [, SEKIKings Canyon National Park, California[, YOSEYosemite National Park, California[. All volcanic eruptions in Iceland, such as the 1973 eruption of Eldfell, the 1783 eruption of Laki, and the 2010 eruption of Eyjafjallajkull, are caused by the North American and the Eurasian Plates moving apart, which is a result of divergent plate boundary forces. Some of the resulting magma makes it all the way to the surface and forms Mount Rainier, Mount Hood, Mount Shasta and other spectacular volcanoes of the Cascade Range. One of them, Kenai Fjords National Park, lies within the accretionary wedge of uplifting oceanic sedimentary strata and hard crust. Layers of sand and mud, deposited on the ocean floor and later turned into the sedimentary rocks sandstone and shale, are seen above the pillows. Imagine if Mt. Katmai volcano did collapse, but unlike Mt. The series of hot spots that has been identified in the Atlantic Ocean may also have existed for several hundred million years, and thus may have contributed to rifting in roughly the same place on at least two separate occasions (Figure \(\PageIndex{13}\)). A series of explosions and ash clouds from the peak between 1914 and 1921 represents the last large volcanic eruption within the lower 48 states prior to Washingtons Mt. The resulting magmas can therefore have a variety of compositions, ranging from the original (low-silica) basalt, to (intermediate-silica) andesite, all the way up to (high-silica) rhyolite. and Alberta are also a result of continent-continent collisions. During the same period, the Atlantic Ocean began to open up between northern Africa and North America, and India broke away from Antarctica. Photo courtesy of Robert J. Lillie. Much of the stable plate is under water and is called the Caribbean ocean . Farther inland, the subducting plate reaches depths where it sweats hot water. Beginning about 30 million years ago, so much of the Farallon Plate was consumed by subduction that the Pacific and North American plates were in contact, forming the San Andreas transform plate boundary in western California. It runs along the west coast of Mexico and western Caribbean countries. The forearc basin is the Willamette Valley in Oregon and Puget Sound in Washington. Plate borders the North American Plate, the South American Plate, the Nazca Plate and the Cocos Plate. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. In doing so the magma is enriched in silica, because high-silica minerals commonly are the first ones to melt. The same forces that shift the land so dramatically also gradually build spectacular landscapes like the coastlines of the Pacific Northwest. More recent studies of continental matchups and the magnetic ages of ocean-floor rocks have enabled us to reconstruct the history of the break-up of Pangea. The west side of California is moving north, and the east side is moving south. WrangellSt. Sediment that has accumulated on the continental slope is thrust up into an accretionary wedge, and compression leads to thrusting within the continental plate (Figure \(\PageIndex{7}\)). Plates move as rigid bodies, so it may seem surprising that the North American Plate can be moving at different rates in different places. The spectacular pillow lavas seen on the road up Hurricane Ridge indicate that lava formed on the sea floor and was later uplifted. Pangea began to rift apart along a line between Africa and Asia and between North America and South America at around 200 Ma. The Cocos Plate is a tectonic plate beneath the Pacific Ocean off the west coast of Central America. Find the boundary between the North American and Cocos plates. Layers of pillow basalt exposed at NPS sites in the Coastal Ranges are evidence that lava flows that formed in the Pacific Ocean were later scraped off the subducting plate and lifted upward as part of the accretionary wedge. Left image Western Mexico, where the young and small Rivera Plate and the adjacent large Cocos Plate are subducting beneath the North American Plate, is a unique The 6-mile (10-kilometer) wide caldera is about 2,000 feet (600 meters) deep. This highly active convergent plate boundary extends along both sides the Philippine Islands, from Luzon in the north to the Celebes Islands in the south. There will also be continued northerly movement of Australia and Indonesia. Detailed Description Map of the North American - Caribbean tectonic plate boundary. By the end of 1967 the Earths surface had been mapped into a series of plates (Figure \(\PageIndex{1}\)). A glance at a map of the western United States might suggest that the Sierra Nevada are a southward continuation of the Cascade Volcanoes. Forty million years ago, a large tectonic plate, known as the Farallon Plate, was between the Pacific and North American plates. When mixed with water from glaciers, snowmelt, and streams, these materials can make very dense, fast-moving volcanic mudflows (known sometimes by the Indonesian term lahar).
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