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An intrusion is a body of igneous (created under intense heat) rock that has crystallized from molten magma. Gravity influences the placement of igneous rocks because it acts on the density differences between the magma and the surrounding wall rocks (country or local rocks).
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Apr 24, 2024 · The minerals that make up igneous rocks crystallize at a range of different temperatures. This explains why a cooling magma can have some crystals within it and yet remain predominantly liquid. The sequence in which minerals crystallize from a magma is known as the Bowen reaction series.
May 16, 2024 · When magma forces itself into cracks, breaks off pieces of rock, and then envelops them, this is called stoping. The resulting fragments are xenoliths[1]. Xenoliths may appear as dark patches within a rock (Figure 7.21). Figure 7.21 Xenoliths of mafic rock in granite, Victoria, B.C.
- Stocks and Batholiths
- Tabular Intrusions
- Pipes
Large irregular-shaped plutons are called either stocks or batholiths, depending on their area. If an irregularly shaped body has an area greater than 100 km2, then it’s a batholith, otherwise it’s a stock. Note that our knowledge of the size of a body can be limited to what we see at the surface. A body with an area of less than 100 km2 exposed at...
Tabular (sheet-like) plutons are classified according to whether or not they are concordant with (parallel to) existing layering (e.g., sedimentary bedding or metamorphic foliation) in the country rock. A sill is concordant with existing layering, and a dike is discordant. If the country rock has no bedding or foliation, then any tabular body withi...
A pipe, as the name suggests, is a cylindrical body with a circular, elliptical, or even irregular cross-section, that serves as a conduit (or pipeline) for the movement of magma from one location to another. Pipes may feed volcanoes, but pipes can also connect plutons.
Simon Holford, in Encyclopedia of Geology (Second Edition), 2021. Introduction. Igneous intrusions represent the fundamental plumbing system in which magma is transported and stored within the Earth's crust.
May 21, 2018 · intrusion In geology, process in which rock material is forced or flows into spaces among other rocks to form intrusive rocks. An igneous intrusion, sometimes called a pluton, consists of magma that never reached the Earth's surface but filled cracks and faults, then cooled and hardened.
Explain how magma composition can be changed by fractional crystallization and partial melting of the surrounding rocks. Apply the criteria for igneous rock classification based on mineral proportions. Describe the origins of phaneritic, porphyritic, and pegmatitic textures.
