Geosyncline

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Geosyncline

Geosyncline theory is an obsolete concept involving vertical crustal movement that has been replaced by plate tectonics

Plate tectonics

Plate tectonics describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s....
to explain crustal movement and geologic features. Geosyncline is a term still occasionally used for a subsiding linear trough that was caused by the accumulation of sedimentary rock

Sedimentary rock

Sedimentary rock is one of the three main Rock types . Sedimentary rock is formed by deposition and consolidation of mineral and organic material and from precipitation of minerals from solution....
strata

Stratum

In geology and related fields, a stratum is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers....
deposited in a basin

Sedimentary basin

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....
and subsequently compressed, deformed, and uplifted into a mountain range

Mountain range

A mountain range is a chain of mountains bordered by highlands or separated from other mountains by mountain pass or valleys. Individual mountains within the same mountain range do not necessarily have the same geology, though they often do; they may be a mix of different orogeny, for example volcanoes, uplifted mountains or Fold mountains...
, with attendant volcanism and plutonism.

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Geosyncline theory is an obsolete concept involving vertical crustal movement that has been replaced by plate tectonics

Plate tectonics

Sedimentary rock

Stratum

In geology and related fields, a stratum is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers....
deposited in a basin

Sedimentary basin

Mountain range

Deposition

Deposition or Depose may refer to:* Deposition , taking testimony outside of court* Deposition , molecules settling out of a solution* Thin-film deposition, any technique for depositing a thin film of material onto a substrate or onto previously deposited layers...
by folding, crumpling, and fault

Fault

Fault may refer to:*Fault , planar rock fractures which show evidence of relative movement*Fault , an abnormal condition or defect at the component, equipment, or sub-system level which may lead to a failure...
ing of the deposits. Intrusion

Intrusion

In geology, an intrusion is a body of igneous rock that has crystallized from molten magma below the surface of the Earth. Bodies of magma that solidify underground before they reach the surface of the earth are called plutons, named for Pluto , the Roman mythology of the underworld....
of crystalline igneous rock and regional uplift along the axis of the trough generally complete the history of a particular geosyncline. It is then transformed into a belt of folded mountains. Thick volcanic sequences, together with graywackes (sandstones rich in rock fragments with a muddy matrix), chert

Chert

Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green ar...
s, and various sediments reflecting deepwater deposition or processes, are deposited in eugeosynclines, the outer deepwater segment of geosynclines.

Geosynclines are divided into miogeosynclines and eugeosynclines, depending on the types of discernible rock strata of the mountain system. A miogeosyncline develops along a continental margin

Continental margin

The continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. Continental margins constitute about 28% of the oceanic area....
on continental crust

Continental crust

The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as Continental shelf....
and is composed of sediments with limestone

Limestone

File:Limestone Formation In Waitomo.jpgLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geology record....
s, sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock Particle size . Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust ....
s and shale

Shale

Shale is a fine-grained sedimentary rock whose original constituents were clay minerals or muds. It is characterized by thin laminae breaking with an irregular curving fracture, often splintery and usually parallel to the often-indistinguishable bedding plane....
s. The occurrences of limestones and well-sorted quartzose sandstones indicate a shallow-water formation, and such rocks form in the inner segment of a geosyncline. The eugeosynclines consist of different sequences of lithologies more typical of deep marine environments. Eugeosynclinal rocks include thick sequences of greywacke

Greywacke

Greywacke is a variety of sandstone generally characterized by its hardness, dark color, and poorly-sorted, angular grains of quartz, feldspar, and small rock fragments set in a compact, clay-fine matrix....
s, chert

Chert

Slate

Slate is a fine-grained, foliation , homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcano ash through low grade regional metamorphism....
s, tuff

Tuff

Tuff is a type of Rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is also sometimes called tufa, particularly when used as construction material....
s and submarine lava

Lava

Lava is molten Rock expelled by a volcano during an eruption. When first expelled from a volcanic vent, it is a liquid at temperatures from 700 ?C to 1,200 ?C ....
s. The eugeosynclinal deposits are typically more deformed, metamorphosed

Metamorphism

Metamorphism is the solid-state Crystallization of pre-existing Rock due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids....
, and intruded by small to large igneous plutons

Intrusion

Flysch

Flysch is a sequence of sedimentary rocks that is deposited in a deep marine sedimentary facies in the foreland basin of a developing orogen. Flysch is typically deposited during an early stage of the orogenesis, when the orogen evolves the foreland basin will become shallower and molasse will be deposited on top of the flysch....
and mélange

Melange

Melange is the name of the fictional psychoactive drug central to the Dune universe of science fiction novels by Frank Herbert, and derivative works....
sediments.

An orthogeosyncline is a linear geosynclinal belt lying between continental and oceanic terranes, and having internal volcanic belts (eugeosynclinal) and external nonvolcanic belts (miogeosynclinal). Also known as geosynclinal couple or primary geosyncline. A miogeosyncline is the nonvolcanic portion of an orthogeosyncline, located adjacent a craton. A zeugogeosyncline is a geosyncline in a craton or stable area within which is also an uplifted area, receiving clastic sediments, also known as yoked basin. A parageosyncline is an epeirogenic geosynclinal basin located within a craton area. A exogeosyncline is a parageosyncline that lies along the cratonal border and obtains its clastic sediments from erosion of the adjacent orthogeosynclinal belt outside the craton. Also known as delta geosyncline; foredeep; or transverse basin.

Several types of "mobile" geosynclinal zones have also been recognized and named. Among the more common of these are the taphrogeosyncline, a depressed block of the Earth's crust that is bounded by one or more high-angle faults and that serves as a site of sediment accumulation; and the paraliageosyncline, a deep geosyncline that passes into coastal plains along continental margins.

History of the concept

The geosyncline concept was first developed by the American geologists James Hall

James Hall (paleontologist)

James Hall was an United States geologist and paleontologist. He was a noted authority on stratigraphy and had an influential role in the development of American paleontology....
and James Dwight Dana

James Dwight Dana

James Dwight Dana was an United States geologist, mineralogist and zoologist. He made important studies of mountain-building, volcano activity, and the origin and structure of continents and oceans....
in the mid 1800s during the classic studies of the Appalachian Mountains

Appalachian Mountains

The Appalachian Mountains or , often called the Appalachians, are a vast mountain range in eastern North America. Definitions vary on the precise boundaries of the Appalachians....
. Dana was first to use the term geosynclinal in reference to a gradually deepening and filling basin resulting from his concept of crustal contraction due to a cooling and contracting Earth. The geosynclinal theory was further developed in the late 19^th and early 20^th centuries and at that time was widely accepted as an explanation for the origin of most mountain ranges until its replacement by the subduction zone and continental collision orogenies

Orogeny

Orogeny refers to natural mountain building, and may be studied as a tectonic structural event, as a geographical event, and a chronological event: orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust, and happen within a specific period of time....
of plate tectonics

Plate tectonics

Plate tectonics describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s....
in the 1960s. Although the usage varied over the following 100 years, a geosyncline is still basically a large linear deepening basin along a continental margin which becomes deformed and then uplifted in parts as a mountainous region.

Geosyncline

History of the concept

See also

External links