Search results
Results from the WOW.Com Content Network
Subsidence frequently causes major problems in karst terrains, where dissolution of limestone by fluid flow in the subsurface creates voids (i.e., caves).If the roof of a void becomes too weak, it can collapse and the overlying rock and earth will fall into the space, causing subsidence at the surface.
Tectonic subsidence is the sinking of the Earth's crust on a large scale, relative to crustal-scale features or the geoid. [1] The movement of crustal plates and accommodation spaces produced by faulting [2] brought about subsidence on a large scale in a variety of environments, including passive margins, aulacogens, fore-arc basins, foreland basins, intercontinental basins and pull-apart basins.
Most of the eastern Indian Ocean and nearly all of the Pacific Ocean margin are examples of active margins. While a weld between oceanic and continental lithosphere is called a passive margin, it is not an inactive margin. Active subsidence, sedimentation, growth faulting, pore fluid formation and migration are all active processes on passive ...
Direct sampling of the rocks themselves is accomplished via the drilling of boreholes and the retrieval of rock samples in the form of both core samples and drill cuttings. These allow geologists to study small samples of the rocks directly and also very importantly allow paleontologists to study the microfossils they contain (micropaleontology).
Subsidence of the lithosphere acts to increase the thickness of the portion of the lowermost crust which behaves viscously. If the freezing of the asthenosphere dominates (2) the system is stable, however if subsidence, and therefore separation of the lower lithosphere dominates (3) the system is unstable.
A pit crater (also called a subsidence crater or collapse crater) is a depression formed by a sinking or collapse of the surface lying above a void or empty chamber, rather than by the eruption of a volcano or lava vent. [1] Pit craters are found on Mercury, Venus, [2] [3] Earth, Mars, [4] and the Moon. [5]
In geology, a basin is a region where subsidence generates accommodation space for the deposition of sediments. A pull-apart basin is a structural basin where two overlapping (en echelon) strike-slip faults or a fault bend create an area of crustal extension undergoing tension, which causes the basin to sink down.
In geology and geophysics, thermal subsidence is a mechanism of subsidence in which conductive cooling of the mantle thickens the lithosphere and causes it to decrease in elevation. This is because of thermal expansion : as mantle material cools and becomes part of the mechanically rigid lithosphere, it becomes denser than the surrounding material.