A fracture zone is a linear feature on the ocean floor—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics . Lithospheric plates on either side of an active transform fault move in opposite directions; here, strike-slip activity occurs. Fracture zones extend past the transform faults, away from the ridge axis; are usually seismically inactive (because both plate segments are moving in the same direction), although they can display evidence of transform fault activity, primarily in the different ages of the crust on opposite sides of the zone.
14-519: The Easter Fracture Zone is an oceanic fracture zone associated with the transform fault extending from the Tuamotu archipelago in the west to the Peru–Chile Trench to the east. The Easter Fracture Zone extends roughly 5900 kilometers from 20°S,131°W to 26°S,78°W. The landscape consists of several ridges and isolated volcanos with maximal peak elevation above the seafloor of 3000m. Because
28-562: A total of 350 km to the west. The section of the Mid-Atlantic Ridge between the two fracture zones is seismically active. The flow of major North Atlantic currents is associated with this fracture zone which hosts a diverse deep water ecosystem. The Heirtzler Fracture Zone was approved by the Advisory Committee on Undersea Features in 1993. The Mendocino Fracture Zone extends for over 4,000 km off
42-667: Is 125 km long and 15 km wide. Gorda plate The Gorda plate , located beneath the Pacific Ocean off the coast of northern California , is one of the northern remnants of the Farallon plate . It is sometimes referred to (by, for example, publications from the USGS Earthquake Hazards Program) as simply the southernmost portion of the neighboring Juan de Fuca plate , another Farallon remnant. Unlike most tectonic plates ,
56-650: The Juan de Fuca Ridge and the Gorda Ridge . The dominating feature of the fracture zone is the 150 km long Blanco Ridge, which is a high-angle, right-lateral strike slip fault with some component of dip-slip faulting . The Charlie-Gibbs Fracture Zone consists of two fracture zones in the North Atlantic that extend for over 2000 km. These fracture zones displace the Mid-Atlantic Ridge
70-681: The Romanche Trench , this fracture zone separates the North Atlantic and South Atlantic oceans. The trench reaches 7,758 m deep, is 300 km long, and has a width of 19 km. The fracture zone offsets the Mid-Atlantic Ridge by more than 640 km. The Sovanco Fracture Zone is a dextral-slip transform fault running between the Juan de Fuca and Explorer Ridge in the North Pacific Ocean . The fracture zone
84-782: The Gorda Basin event). The easterly side is the Cascadia subduction zone where the plate subducts under the North American plate in northern California. The southerly side is a transform boundary with the Pacific plate along the Mendocino Fault . The westerly side is a divergent boundary with the Pacific plate forming the Gorda Ridge . This ridge provides morphological evidence of differing spreading rates, with
98-467: The Gorda plate experiences significant intraplate deformation inside its boundaries. Numerous faults have been mapped in both the sediments and basement of the Gorda Basin, which is in the interior of the plate south of 41.6°N. Stresses from the neighboring North American plate and Pacific plate cause frequent earthquakes in the interior of the plate, including the 1980 Eureka earthquake (also known as
112-399: The coast of California and separates the Pacific plate and Gorda plate . The bathymetric depths on the north side of the fracture zone are 800 to 1,200 m shallower than to the south, suggesting the seafloor north of the ridge to be younger. Geologic evidence backs this up, as rocks were found to be 23 to 27 million years younger north of the ridge than to the south. Also known as
126-822: The local seafloor has depths around 4000m to the north of the fracture zone and 3400m to the south of the fracture zone, most of its volcanic peaks form seamounts . They do rise above sea level at the Pitcairn Islands and Easter Island . This tectonics article is a stub . You can help Misplaced Pages by expanding it . Fracture zone In actual usage, many transform faults aligned with fracture zones are often loosely referred to as "fracture zones" although technically, they are not. They can be associated with other tectonic features and may be subducted or distorted by later tectonic activity. They are usually defined with bathymetric , gravity and magnetic studies. Mid-ocean ridges are divergent plate boundaries. As
140-558: The northern portion of the ridge being narrow, and the southern portion being wide. The northerly side is a transform boundary with the Juan de Fuca plate , the Blanco Fracture Zone . The subducting Gorda plate is connected with the volcanoes in northern California, namely, Mount Shasta and Lassen Peak . Lassen Peak last erupted in 1914–1917. 41°12′N 126°24′W / 41.2°N 126.4°W / 41.2; -126.4 This tectonics article
154-406: The offset in the magnetic striping, one can then determine the rate of past plate motions. In a similar method, one can use the relative ages of the seafloor on either side of a fracture zone to determine the rate of past plate motions. By comparing how offset similarly aged seafloor is, one can determine how quickly the plate has moved. The Blanco Fracture Zone is a fracture zone running between
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#1732772557706168-409: The plates on either side of an offset mid-ocean ridge move, a transform fault forms at the offset between the two ridges. Fracture zones and the transform faults that form them are separate but related features. Transform faults are plate boundaries, meaning that on either side of the fault is a different plate. In contrast, outside of the ridge-ridge transform fault, the crust on both sides belongs to
182-408: The same plate, and there is no relative motion along the junction. The fracture zone is thus the junction between oceanic crustal regions of different ages. Because younger crust is generally higher due to increased thermal buoyancy , the fracture zone is characterized by an offset in elevation with an intervening canyon that may be topographically distinct for hundreds or thousands of kilometers on
196-486: The sea floor. As many areas of the ocean floor, particularly the Atlantic Ocean, are currently inactive, it can be difficult to find past plate motion. However, by observing the fracture zones, one can determine both the direction and rate of past plate motion. This is found by observing the patterns of magnetic striping on the ocean floor (a result of the reversals of Earth's magnetic field over time). By measuring
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