Search results
Results from the WOW.Com Content Network
Magma that cools slowly within a magma chamber usually ends up forming bodies of plutonic rocks such as gabbro, diorite and granite, depending upon the composition of the magma. Alternatively, if the magma is erupted it forms volcanic rocks such as basalt , andesite and rhyolite (the extrusive equivalents of gabbro, diorite and granite ...
Igneous differentiation. In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption. The sequence of (usually increasingly silicic) magmas produced by igneous differentiation is ...
Intermediate composition magma, such as andesite, tends to form cinder cones of intermingled ash, tuff and lava, and may have a viscosity similar to thick, cold molasses or even rubber when erupted. Felsic magma, such as rhyolite, is usually erupted at low temperature and is up to 10,000 times as viscous as basalt. Volcanoes with rhyolitic ...
AFM diagram showing the relative proportions of the oxides of alkalis (A), iron (F), and magnesium (M), with arrows showing the compositional change path of the magmas in the tholeiitic and the calc-alkaline magma series (BT=tholeiitic basalt, FB=ferro-basalt, ABT=tholeiitic basaltic andesite, AT=tholeiitic andesite, D=dacite, R=rhyolite, B=basalt, AB=basaltic andesite, A=andesite; dashed line ...
The magma then rises through the crust, incorporating silica-rich crustal rock, leading to a final intermediate composition. When the magma nears the top surface, it pools in a magma chamber within the crust below the stratovolcano. [7] The processes that trigger the final eruption remain a question for further research.
Dacite (/ ˈdeɪsaɪt /) is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz.
Description. 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 ...
In essence, fractional crystallization is the removal of early formed crystals from an originally homogeneous magma (for example, by gravity settling) so that these crystals are prevented from further reaction with the residual melt. [3] The composition of the remaining melt becomes relatively depleted in some components and enriched in others ...