Concept
Mid-ocean ridge
Related concepts (45)
Large low-shear-velocity provinces
Large low-shear-velocity provinces, LLSVPs, also called LLVPs or superplumes, are characteristic structures of parts of the lowermost mantle (the region surrounding the outer core) of Earth. These provinces are characterized by slow shear wave velocities and were discovered by seismic tomography of deep Earth. There are two main provinces: the African LLSVP and the Pacific LLSVP. Both extend laterally for thousands of kilometers and possibly up to 1,000 kilometres vertically from the core–mantle boundary.
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. Magnetic anomalies are generally a small fraction of the magnetic field.
Continental margin
A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin consists of three different features: the continental rise, the continental slope, and the continental shelf. The continental shelf is the relatively shallow water area found in proximity to continents. Continental margins constitute about 28% of the oceanic area.
Sheeted dyke complex
A sheeted dyke complex, or sheeted dike complex, is a series of sub-parallel intrusions of igneous rock, forming a layer within the oceanic crust. At mid-ocean ridges, dykes are formed when magma beneath areas of tectonic plate divergence travels through a fracture in the earlier formed oceanic crust, feeding the lavas above and cooling below the seafloor forming upright columns of igneous rock. Magma continues to cool, as the existing seafloor moves away from the area of divergence, and additional magma is intruded and cools.
Geothermal gradient
Geothermal gradient is the rate of change in temperature with respect to increasing depth in Earth's interior. As a general rule, the crust temperature rises with depth due to the heat flow from the much hotter mantle; away from tectonic plate boundaries, temperature rises in about 25–30 °C/km (72–87 °F/mi) of depth near the surface in most of the world. However, in some cases the temperature may drop with increasing depth, especially near the surface, a phenomenon known as or geothermal gradient.