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The term sedimentary basin is used to refer to any geographical feature exhibiting subsidence and consequent infilling by sedimentation. As the sediments are buried, they are subjected to increasing pressure and begin the process of lithification. A road destroyed by subsidence and shear. ...
The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin, Canberra. ...
Lithification, from the Greek word lithos meaning rock, is the process whereby sediments compact under pressure, expel connate fluids, and gradually become solid rock. ...
Methods of Formation
It is common to categorise sedimentary basins according to the mechanism of formation: tectonic compression (e.g., foreland basins, caused by lithospheric flexure), tectonic extension (e.g., back-arc basins, caused by lithospheric stretching), and tectonic strike-slip (such as pull-apart basins).
Lithospheric stretching If the lithosphere is caused to stretch horizontally, by mechanisms such as ridge-push or trench-pull, the effect is believed to be twofold. The lower, hotter part of the lithosphere will "flow" slowly away from the main area being stretched, whilst the upper, cooler and more brittle crust will tend to fault (crack) and fracture. The combined effect of these two mechanisms is for the earth's surface in the area of extension to subside, creating a geographical depression which is then often infilled with water and/or sediments. (An analogy might be a piece of rubber, which thins in the middle when stretched.) The tectonic plates of the Lithosphere on Earth. ...
Earth cutaway from core to exosphere. ...
An example of a basin caused by lithospheric stretching is the North Sea - also an important location for significant hydrocarbon reserves. Another such feature is the Basin and Range province which covers most of the USA state of Nevada, forming a series of horst and graben structures. The North Sea is a sea of the Atlantic Ocean, located between the coasts of Norway and Denmark in the east, the coast of the British Isles in the west, and the German, Dutch, Belgian and French coasts in the south. ...
Hydrocarbons are refined at oil refineries and processed at chemical plants In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H). ...
Basin and Range index map - USGS The Basin and Range Province is a particular type of topography that covers much of the southwestern United States and northwestern Mexico that is typified by elongate north-south trending arid valleys bounded by mountain ranges which also bound adjacent valleys. ...
USGS image In physical geography and geology, a horst is the raised fault block bounded by normal faults. ...
USGS image A graben is a depressed block of land bordered by parallel faults. ...
Another expression of lithospheric stretching results in the formation of ocean basins with central ridges; The Red Sea is in fact an incipient ocean, in a plate tectonic context. The mouth of the Red Sea is also a tectonic triple junction where the Indian Ocean Ridge, Red Sea Rift and East African Great Rift Valley meet. This triple junction is also the only place on the planet where seafloor crust is subaerially exposed. The reason for this is twofold, due to a high thermal buoyancy of the junction, and a local crumpled zone of seafloor crust acting as a dam against the Red Sea. Location of the Red Sea Image:Red Seaimage. ...
A triple junction is the point where three tectonic plates diverge. ...
The term subaerial, mainly used in geology, describes events or structures located at the Earths surface, under the air. This is to be contrasted with submarine events or structures, those located under the sea. ...
Lithospheric compression/shortening and flexure If a load is placed on the lithosphere, it will tend to flex in the manner of an elastic plate. The rate and degree of flexure is a function of the flexural rigidity of the lithosphere, which is itself a function of the lithospheric mineral composition and thermal regime. The nature of the load is varied. For instance, the Hawaiian Islands chain of volcanic edifices has sufficient mass to cause deflection in the lithosphere. Flexural rigidity is defined as the force couple required to bend a rigid structure to a unit curvature. ...
Map of the Hawaiian Islands, a chain of islands that stretches 2,400 km in a northwesterly direction from the southern tip of the Island of Hawai‘i. ...
The obduction of one tectonic plate onto another also causes a load and often results in the creation of a foreland basin, such as the Po basin next to the Alps in Italy, the Molasse Basin next to the Alps in Germany, or the Ebro basin next to the Pyrenees in Spain. Obduction is the overthrusting of continental crust by oceanic crust or mantle rocks. ...
A foreland basin is a depressed area of the Earths crust landward of a young mountain chain, and parallel to it. ...
Central Pyrenees. ...
Strike-slip deformation Deformation of the lithosphere in the plane of the earth (i.e. such that faults are vertical) occurs as a result of horizontal differential stresses. The resulting zones of subsidence are known as strike-slip or pull-apart basins. Basins formed through strike-slip action occur where a vertical fault plane curves. When the curve in the fault plane moves apart, a region of transtension results, creating a basin. Another term for a transtensional basin is a rhombochasm. A classic rhombochasm is illustrated by the Dead Sea rift, where northward movement of the Arabian Plate relative to the Anatolian Plate has caused a rhombochasm. The Dead Sea (Hebrew: ; Arabic: ‎) is both the lowest point on Earth at 418 metres (1,371 ft) below sea level and falling[2], and the deepest hypersaline lake in the world at 330 m (1,083 ft) deep and 799 m (2,621 ft) below sea level. ...
The Arabian plate is shown in bright yellow on this map The Arabian Plate is a continental tectonic plate covering the Arabian peninsula and extending northward to Turkey. ...
The Anatolian Plate is a continential tectonic plate consisting primarily of the country of Turkey. ...
The opposite effect is that of transpression, where converging movement of a curved fault plane causes collision of the opposing sides of the fault. An example is the San Bernardino Mountains north of Los Angeles, which result from convergence along a curve in the San Andreas fault system. The Northridge earthquake was caused by vertical movement along local thrust and reverse faults bunching up against the bend in the otherwise strike-slip fault environment. San Bernardino Mountains The San Bernardino Mountains are short transverse mountain range northeast of Los Angeles in southern California in the United States. ...
Flag Seal Nickname: City of Angels Location Location within Los Angeles County in the state of California Coordinates , Government State County California Los Angeles County Mayor Antonio Villaraigosa (D) Geographical characteristics Area City 1,290. ...
View of the San Andreas Fault on the Carrizo Plain in central California San Andreas Fault is a geological fault that runs a length of roughly 800 miles (1287 kilometres) through California, United States. ...
The 1994 Northridge earthquake occurred on January 17, 1994 at 4:30:55 AM Pacific Standard Time in the city of Los Angeles, California, falling on Martin Luther King Day in 1994. ...
Ongoing development of sedimentary basins As more and more sediment is deposited into the basin, the weight of all the newer sediment may cause the basin to subside further because of isostasy. A basin can continue having sediment deposited into it, and continue to subside, for long periods of geological time; this can result in basins many kilometres in thickness. Geologic faults can often occur around the edge of, and within, the basin, as a result of the ongoing slippage and subsidence. Isostasy is a term used in Geology to refer to the state of gravitational equilibrium between the Earths lithosphere and asthenosphere such that the tectonic plates float at an elevation which depends on their thickness and density. ...
Old fault exposed by roadcut near Harrisburg, Pennsylvania. ...
Study of sedimentary basins The study of sedimentary basins as a specific entity in themselves is often referred to as basin modelling or Sedimentary Basin Analysis. The need to understand the processes of basin formation and evolution are not restricted to the purely academic. Indeed, sedimentary basins are the location for almost all of the world's hydrocarbon reserves and as such are the focus of intense commercial interest. Basin modelling is the term broadly applied to a group of geological disciplines that can be used to analyse the formation and evolution of sedimentary basins, often but not exclusively to aid evaluation of potential hydrocarbon reserves. ...
Sedimentary basin analysis is a geologic method by which the history of a sedimentary basin is revealed, by analyzing the sediment fill itself. ...
Hydrocarbons are refined at oil refineries and processed at chemical plants In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H). ...
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