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A laccolith is a type of igneous intrusion, formed when magma forces its way upwards through the Earth's crust but cools and solidifies before reaching the surface. Laccoliths are distinguished from other igneous intrusions by their dome-shaped upper surface and level base. They are assumed to be fed by a conduit from below, though this is ...
Compatibility diagrams provide an excellent way to analyze how variations in the rock's composition affect the mineral paragenesis that develops in a rock at particular pressure and temperature conditions. [1] Because of the difficulty of depicting more than three components (as a ternary diagram), usually only the three most important ...
In geology, an igneous intrusion (or intrusive body[1] or simply intrusion[2]) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and compositions, illustrated by examples like the Palisades Sill of New York and New Jersey; [3] the ...
Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet 's mantle or crust.
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium -rich varieties of plagioclase ...
QAPF diagram for the classification of plutonic rocks Devils Tower, United States, an igneous intrusion exposed when the surrounding softer rock eroded away. Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form intrusions, such as batholiths, dikes, sills, laccoliths, and volcanic necks.
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in ...
Cinder cone. A cinder cone (or scoria cone[1]) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. [2][3] The pyroclastic fragments are formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent.