Search results
Results from the WOW.Com Content Network
The average density of basalt is 2.9 g/cm 3, compared, for example, to granite’s typical density of 2.7 g/cm 3. [16] The viscosity of basaltic magma is relatively low—around 10 4 to 10 5 cP—similar to the viscosity of ketchup, but that is still several orders of magnitude higher than the viscosity of water, which is about 1 cP). [17]
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 ...
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. On Earth, magma forms by partial melting of silicate rocks either in the mantle, continental or oceanic crust. Evidence ...
Magma originating in the mantle rises into the asthenosphere and lithosphere. A chain of volcanoes is created as the lithosphere moves over the source of magma. In geology, hotspots (or hot spots) are volcanic locales thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. [1]
Basaltic magma is the most abundant in iron, magnesium, and calcium but the lowest in silica, potassium, and sodium. [1], [3] The composition of silica within basaltic magma ranges from 45-55 weight percent (wt.%), or mass fraction of a species. [1] It forms in temperatures ranging from approximately 1830 °F to 2200 °F.
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 ...
Composite or stratovolcanoes often have andesitic magma and typically form the extrusive rock andesite. Andesitic magma is composed of many gases and melted mantle rocks. [2] Cinder or scoria cones violently expel lava with high gas content, [2] and due to the vapor bubbles in this mafic lava, the extrusive basalt scoria is formed. [6]
When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes filled with gas called vesicles. [ 2 ] A related texture is amygdaloidal in which the volcanic rock, usually basalt or andesite , has cavities, or vesicles, that are filled with secondary ...