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In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria ) is a large syncline with superimposed smaller folds. [ 1 ]
See the main article on folds for a fuller treatment of fold types and nomenclature but in brief, an anticline is an arch-like fold whereas a syncline is its converse; a downfold. Antiforms, anticlinoria, synforms and synclinoria are variations on these. A monocline (or, rarely, a monoform) is a
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
A fold axis "is the closest approximation to a straight line that when moved parallel to itself, generates the form of the fold". [2] (Ramsay 1967). A fold that can be generated by a fold axis is called a cylindrical fold. This term has been broadened to include near-cylindrical folds. Often, the fold axis is the same as the hinge line. [3] [4]
If the angle between the limbs is large (70–120 degrees), then the fold is an "open" fold, but if the angle between the limbs is small (30 degrees or less), then the fold is a "tight" fold. [4] If an anticline plunges (i.e., the anticline crest is inclined to the Earth's surface), it will form V s on a geologic map view that point in the ...
Development of a mountain range by sedimentation of a geosyncline and isostatic uplifting. This is the "collapse" of the geosyncline. A geosyncline (originally called a geosynclinal) is an obsolete geological concept to explain orogens, which was developed in the late 19th and early 20th centuries, before the theory of plate tectonics was envisaged.
Chevron folding preferentially occurs when the bedding regularly alternates between contrasting competences. [1] Turbidites, characterized by alternating high-competence sandstones and low-competence shales, provide the typical geological setting for chevron folds to occur. Perpetuation of the fold structure is not geometrically limited.
The formation of an asymmetric anticline-syncline fold pair accommodates the continuing displacement. As displacement continues, the thrust tip starts to propagate along the axis of the syncline. Such structures are also known as tip-line folds. Eventually, the propagating thrust tip may reach another effective decollement layer, and a ...