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Kane Fracture Zone
The Kane Fracture Zone is a medium-offset transform fault zone located on the Mid-Atlantic Ridge (MAR). It lies just to the north of the Kane Megamullion, an oceanic core complex that forms the footwall of a long-lived low-angle detachment fault. The Mid-Atlantic Ridge near the Kane Fracture zone (known as the MARK area) has been the focus of detailed scientific investigations, notably Expeditions 106 and 109 of the Ocean Drilling Program, as well as numerous other geological and geophysical studies. The Kane Fracture Zone offsets the MAR left-laterally by at 24°N. Its fossil trace on the western side of the MAR stretches some westward to the 80 Ma isochron (anomaly Anomaly may refer to: Science Natural *Anomaly (natural sciences) ** Atmospheric anomaly ** Geophysical anomaly Medical * Congenital anomaly (birth defect), a disorder present at birth ** Physical anomaly, a deformation of an anatomical struct ... 34). Major changes or bends along this trace occur at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transform Fault
A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction zone. A transform fault is a special case of a ''strike-slip fault'' that also forms a plate boundary. Most such faults are found in oceanic crust, where they accommodate the lateral offset between segments of divergent boundaries, forming a zigzag pattern. This is a result of oblique seafloor spreading where the direction of motion is not perpendicular to the trend of the overall divergent boundary. A smaller number of such faults are found on land, although these are generally better-known, such as the San Andreas Fault and North Anatolian Fault. Nomenclature Transform boundaries are also known as conservative plate boundaries because they involve no addition or loss of lithosphere at the Earth's surface. Background Geophysicist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mid-Atlantic Ridge
The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North American from the Eurasian Plate and the African Plate, north and south of the Azores Triple Junction respectively. In the South Atlantic, it separates the African and South American plates. The ridge extends from a junction with the Gakkel Ridge (Mid-Arctic Ridge) northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level, for example in Iceland. The ridge has an average spreading rate of about per year. Discovery A ridge under the northern Atlantic Ocean was first inferred by Matthew Fontaine Maury in 1853, based on soundings by the USS ''Dolphin''. The existence of the ridge and its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Core Complex
An oceanic core complex, or megamullion, is a seabed geologic feature that forms a long ridge perpendicular to a mid-ocean ridge. It contains smooth domes that are lined with transverse ridges like a corrugated roof. They can vary in size from 10 to 150 km in length, 5 to 15 km in width, and 500 to 1500 m in height. History, distribution and exploration The first oceanic core complexes described were identified in the Atlantic Ocean. Since then numerous such structures have been identified primarily in oceanic lithosphere formed at intermediate, slow- and ultra-slow spreading mid-ocean ridges, as well as back-arc basins. Examples include 10-1000 square km expanses of ocean floor and therefore of the oceanic lithosphere, particularly along the Mid-Atlantic Ridge and the Southwest Indian Ridge. Some of these structures have been drilled and sampled, showing that the footwall can be composed of both mafic plutonic and ultramafic rocks (gabbro and peridotite primarily, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Footwall
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocean Drilling Program
The Ocean Drilling Program (ODP) was a multinational effort to explore and study the composition and structure of the Earth's oceanic basins. ODP, which began in 1985, was the successor to the Deep Sea Drilling Project initiated in 1968 by the United States. ODP was an international effort with contributions of Australia, Germany, France, Japan, the United Kingdom and the ESF Consortium for Ocean Drilling (ECOD) including 12 further countries. The program used the drillship ''JOIDES Resolution'' on 110 expeditions (legs) to collect about 2,000 deep sea cores from major geological features located in the ocean basins of the world. Drilling discoveries led to further questions and hypotheses, as well as to new disciplines in earth sciences such as the field of paleoceanography. In 2004 ODP transformed into the Integrated Ocean Drilling Program (IODP). See also * Project Mohole * Deep Sea Drilling Program * Integrated Ocean Drilling Program * Allison Guyot Allison Guyot (fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isochron
In the mathematical theory of dynamical systems, an isochron is a set of initial conditions for the system that all lead to the same long-term behaviour. Mathematical isochron An introductory example Consider the ordinary differential equation for a solution y(t) evolving in time: : \frac + \frac = 1 This ordinary differential equation (ODE) needs two initial conditions at, say, time t=0. Denote the initial conditions by y(0)=y_0 and dy/dt(0)=y'_0 where y_0 and y'_0 are some parameters. The following argument shows that the isochrons for this system are here the straight lines y_0+y'_0=\mbox. The general solution of the above ODE is :y=t+A+B\exp(-t) Now, as time increases, t\to\infty, the exponential terms decays very quickly to zero (exponential decay). Thus ''all'' solutions of the ODE quickly approach y\to t+A. That is, ''all'' solutions with the same A have the same long term evolution. The exponential decay of the B\exp(-t) term brings together a host of solution ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Anomaly
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material. The magnetic variation (geomagnetic reversals) in successive bands of ocean floor parallel with mid-ocean ridges was important evidence for seafloor spreading, a concept central to the theory of plate tectonics. Measurement Magnetic anomalies are generally a small fraction of the magnetic field. The total field ranges from 25,000 to 65,000 nanoteslas (nT). To measure anomalies, magnetometers need a sensitivity of 10 nT or less. There are three main types of magnetometer used to measure magnetic anomalies: # The fluxgate magnetometer was developed during World War II to detect submarines. It measures the component along a particular axis of the sensor, so it needs to be oriented. On land, it is often oriented vertically, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
