Search results
Results from the WOW.Com Content Network
Volcanic passive margins represent one endmember transitional crust type, the other endmember (amagmatic) type is the rifted passive margin. Volcanic passive margins also are marked by numerous dykes and igneous intrusions within the subsided continental crust. There are typically a lot of dykes formed perpendicular to the seaward-dipping lava ...
Norwegian Margin; US Atlantic Margin; Map showing the distribution of Earth's passive margins with known volcanic and non-volcanic margins distinguished. The margins are marked with color masks where the darkest blues and reds are non-volcanic and volcanic passive margins, respectively.
Most passive margins eventually transition into active margins: where the oceanic plate becomes too heavy due to cooling, it disconnects from the continental crust, and starts subducting below it, forming a new subduction zone. [122] Sixteen principal tectonic plates of the continents and the floor of the oceans
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.
Plate tectonics is a theory developed during the 1960s which describes the movement of continents by way of the separation and collision of crustal plates. It is in a sense structural geology on a planet scale, and is used throughout structural geology as a framework to analyze and understand global, regional, and local scale features.
A detachment fault is a gently dipping normal fault associated with large-scale extensional tectonics. [1] Detachment faults often have very large displacements (tens of km) and juxtapose unmetamorphosed hanging walls against medium to high-grade metamorphic footwalls that are called metamorphic core complexes .
As the passive margin matures, the crust and uppermost mantle become colder and stronger, so that the compensating deflection in the base of the lithosphere is broader than the actual rift. Higher flexural strength results in a broadening of the gravity anomaly with time.
A horst is a section of crust that has been lifted relative to the blocks on either side, which is a result of its bounding faults dipping away from each other. [2] Horsts can form features such as plateaus, mountain ranges or ridges on either side of the valleys.