Intrusion in the context of "Gabbro"

Magma (from Ancient Greek μάγμα (mágma) 'thick unguent') is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as lava) is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles.

Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such as a dike, a sill, a laccolith, a pluton, or a batholith.

In structural geology, a fold is a stack of originally planar surfaces, such as sedimentary strata, that are bent or curved ("folded") during permanent deformation. Folds in rocks vary in size from microscopic crinkles to mountain-sized folds. They occur as single isolated folds or in periodic sets (known as fold trains). Synsedimentary folds are those formed during sedimentary deposition.

Folds form under varied conditions of stress, pore pressure, and temperature gradient, as evidenced by their presence in soft sediments, the full spectrum of metamorphic rocks, and even as primary flow structures in some igneous rocks. A set of folds distributed on a regional scale constitutes a fold belt, a common feature of orogenic zones. Folds are commonly formed by shortening of existing layers, but may also be formed as a result of displacement on a non-planar fault (fault bend fold), at the tip of a propagating fault (fault propagation fold), by differential compaction or due to the effects of a high-level igneous intrusion e.g. above a laccolith.

The Rhyacian Period (/raɪˈeɪsiən/; from Ancient Greek ῥύαξ (rhúax) 'stream of lava') is the second geologic period in the Paleoproterozoic Era and lasted from 2300 Mya to 2050 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.

The Bushveld Igneous Complex and some other similar intrusions formed during this period.

The Central Atlantic magmatic province (CAMP) is the Earth's largest continental large igneous province (LIP), covering an area of roughly 11 million km. It is composed mainly of basalt that formed before Pangaea broke up in the Mesozoic Era, near the end of the Triassic and the beginning of the Jurassic periods. The subsequent breakup of Pangaea created the Atlantic Ocean, but the massive igneous upwelling provided a legacy of basaltic dikes, sills, and lavas now spread over a vast area around the present central North Atlantic Ocean, including large deposits in northwest Africa, southwest Europe, as well as northeast South America and southeast North America (found as continental tholeiitic basalts in subaerial flows and intrusive bodies). The name and CAMP acronym were proposed by Andrea Marzoli (Marzoli et al. 1999) and adopted at a symposium held at the 1999 Spring Meeting of the American Geophysical Union.

The CAMP volcanic eruptions occurred about 201 million years ago and had four separate eruptive cycles. Each pulse lasted no more than 100 years each, spread out over ~600,000 years. The resulting large igneous province is, in area covered, the most extensive on Earth. The eruptive volume is between two and six million cubic kilometres, making it one of the most voluminous eruptions in Earth's history. Some research shows that mafic eruptions started as early as 100 kya prior to the main pulse eruptions began.

Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of magma or lava. Volcanism is the surface expression of magmatism.

Magmatism is one of the main processes responsible for mountain formation. The nature of magmatism depends on the tectonic setting. For example, andesitic magmatism is associated with the formation of island arcs at convergent plate boundaries while basaltic magmatism is found at mid-ocean ridges during sea-floor spreading at divergent plate boundaries.

A laccolith is a body of intrusive rock with a dome-shaped upper surface and a level base, fed by a conduit from below. A laccolith forms when magma (molten rock) rising through the Earth's crust begins to spread out horizontally, prying apart the host rock strata. The pressure of the magma is high enough that the overlying strata are forced upward, giving the laccolith its dome-like form.

Over time, erosion can expose the solidified laccolith, which is typically more resistant to weathering than the host rock. The exposed laccolith then forms a hill or mountain. The Henry Mountains of Utah, US, are an example of a mountain range composed of exposed laccoliths. It was here that geologist Grove Karl Gilbert carried out pioneering field work on this type of intrusion. Laccolith mountains have since been identified in many other parts of the world.

Earth materials include minerals, rocks, soil and water. These are the naturally occurring materials found on Earth that constitute the raw materials upon which our global society exists. Earth materials are vital resources that provide the basic components for life, agriculture and industry.

Cross-cutting relationships is a principle of geology that states that the geologic feature which cuts another is the younger of the two features. It is a relative dating technique in geology. It was first developed by Danish geological pioneer Nicholas Steno in Dissertationis prodromus (1669) and later formulated by James Hutton in Theory of the Earth (1795) and embellished upon by Charles Lyell in Principles of Geology (1830).